+++ #23 Subject: Bending Wing Steel Parts From: Russ Erb I've finally started cutting out steel pieces for the wing parts. I've been using the shear from Harbor Freight that Mike Meador mentioned a few months ago. I'll give a complete report on it sometime later. For now, I'll say that I've been able to cut up to 0.080 thick 4130 steel with no problem. I haven't tried anything thicker yet. I'll be using the die shown on page 2 of the July 1998 newsletter to bend the ends of the flap and aileron drives and the flap hinge mounts. Pat Fagan also pointed out to me that I can use the same die to bend the flap and aileron hinges by making the blank wider, then bandsawing off the unneeded side. The benefit of this method is a clean bend. If I had just hammered the steel sheet over a block, there is a possibility that the piece would stretched as one part was bent and then the next part next to it. I'm guessing, since I haven't actually tried it. My question to the group is how did you/how do you plan to bend the inboard flap lever (sheet 12). The bend lines of the two flanges are not parallel. Should I just hammer it over a block or does someone have a better way? +++ #24 Subject: Re: Bending Wing Steel Parts From: Float-by Shooter > My question to the group is how did you/how do you plan to bend the > inboard flap lever (sheet 12). The bend lines of the two flanges are > not parallel. Should I just hammer it over a block or does someone > have a better way? I think it is called a big brake ($$$). Actually I think that V-block press from the article that Tim sent out to some of us would probably do the job well, or a set of dies for our regular hydraulic presses. I saw in the Eastwood Company's catalog (www.eastwoodco.com) they sell a "vise brake" for doing thinner stock in a bench vise, and I'm wondering how the jaws would hold up on 4130 under the force of a hydraulic press, might be worth a shot. I don't know if they would be long enough however, and I would have to build a fixture to hold them in place. When I return home one of my projects is going to be to construct some sort of die for my press, if it works out you can expect to read about it here in a couple of months probably. I'm scheduled for my first night flight tomorrow to be followed by my cross-country work, so hopefully I will be outta here (Snohomish, WA) real soon. I'm really itching to get back to work on the Bearhawk. Of course living on the field here doesn't help that any- there is a beautiful white Maule that operates out of here and every time I see it there is this overpowering urge to cut and bend metal... +++ #43 Subject: Welding Flap Arms From: Russell E. Erb Ah, the love-hate relationship with the Bearhawk continues, though probably more hate lately. Today I finally welded up the first actual welded piece for my airplane, and it even appears to be airworthy. For various reasons, I ended up working on the Flap Arm (see drawing 12). Several things became apparent while doing this. I cut out the big flat metal pieces, sanded to shape, and match drilled the pilot holes. The 3/16" and 3/8" holes were straightforward. I had bought a #5 Unibit (big buck$), hoping to use it to cut the 7/8" hole. With the drill press set at 250 RPM, as slow as it will go, things went fine up through 3/4", but that last 1/8" just wouldn't cut. It was as though I had exceeded the capabilities of the system. I tried several different ideas to make it work, but nothing did. I ended up grinding out the rest of the hole with a Moto-tool. The little washer-like pieces are a pain. I started out forming them from scratch from 0.063 4130 sheet, first drilling the 3/8" hole and then shearing and sanding around the hole until I got something resembling a washer. After doing about 3 of these, which ended up looking like what you get if you were to draw a circle freehand around another circle (i.e. not pretty), another idea struck me. I went to a box of washers for 1/4" carriage bolts (the kind you get at your friendly hardware store) and noticed that they were about the right outside diameter. The thickness varied from 0.050 to 0.063. They weren't 4130, but it didn't really matter since the sole purpose of these washers is to keep the flap spring in place--hardly structural. A quick test confirmed that the metal was weldable. To make the washers usable, the 5/16" hole was drilled out to 3/8" with a Unibit and the edge of the washer held in a vise. The hole was slightly enlarged with a reamer wobbled in the hole to make it fit on the tube. That was the easy part... I cut the 3/8" tube and 7/8" tubes to length per the plan. I noticed a 9/32" dimension called out on the plan, but it didn't measure to that. You'll note that the plan shows three neat welds on the 3/8" piece, at the base plate and on each washer. In my experience, they didn't turn out that way. I first welded the inner washer to the 3/8" tube. The fillet ended up large enough that some had to be sanded off to put the tube in the base plate. Now the frustrating part started. Trying to weld just the tube to the baseplate was impossible. The end result was that the previous fillet was welded to the base plate, such that the filler rod metal pretty much filled up the entire gap between the baseplate and the inner washer. It was like an entire cylinder of metal sticking up from the baseplate. That is, except for the areas where the washer had been burned away and was no longer circular. I tried it again on the next part and got the same ugly result. I was not pleased... I was about to trash the parts and try to figure out another procedure to make the part, although I wasn't convinced that it would come out any better. Then I thought, how do welders fix problems like this? I picked the torch up again, and using the filler rod built up the areas where the washer had burned away. After waiting for the part to cool, I used the edge of a belt sander to sand the washer area down flat and circular again. It started to look reasonable again. You may have read not to sand a weld bead to improve its appearance. That's in reference to a structural joint, where the fillet adds to the strength. Remember, this weld in pretty much non-structural. After this, the second washer went on reasonably easy. By comparison, the 7/8" tube was a joy to weld on. +++ #46 Subject: Re: Welding Flap Arms From: Float-by Shooter > a #5 Unibit (big buck$), hoping to use it to cut the 7/8" hole. With the > drill press set at 250 RPM, as slow as it will go, things went fine up > through 3/4", but that last 1/8" just wouldn't cut. It was as though I had > exceeded the capabilities of the system. I tried several different ideas Were you using a cutting lube of some kind? I also used a unibit to make those holes with excellent results, using some Marvel Mystery Oil to lube the bit. Mainly because I had a can of it sitting on the workbench at the time and didn't know what the "proper" cutting lube should be. Another thing I've been doing is drilling the holes undersize, then match reaming them with a chucking reamer in the drill press. The holes turn out much better than I have been able to produce with regular drill bits, I always seem to bugger them up somehow. > The little washer-like pieces are a pain. I started out forming them > from scratch from 0.063 4130 sheet, first drilling the 3/8" hole and > then shearing and sanding around the hole until I got something > resembling a washer. After doing about 3 of these, which ended up > looking like what you get if you were to draw a circle freehand around > another circle (i.e. not pretty), another idea struck me. I used the washer like pieces as a way of using up little bits of 4130 that were too small for anything else. I did similar to your first attempts for all of mine. I made a stencil with a piece of scrap aluminum using the unibit , and drew the outer circle with a sharpie marker, and holding the metal in a pliers took it down to the line with the disc sander. My only problem was not getting it so hot that the line would burn away. The circles aren't perfect but good enough for what they are for. I went to all this trouble and a few days later found the right washers in a catalog somewhere..... > You'll note that the plan shows three neat welds on the 3/8" piece, at > the base plate and on each washer. In my experience, they didn't turn > out that way. If that part was one of the first welding jobs you tackled, you have my respect. I'm hoping that with TIG I can keep the weld beads small in those areas, but first I have to teach myself how to operate the machine which may take a while. +++ #96 Subject: Mounting Rod Ends From: Russ Erb This is mainly a question for Mike Meador, but, of course, anyone can chime in. The plans clearly show using rivets to hold the rod end bearings into the hinge mounts for the flap and aileron. What is not specified: What kind of rivets are these? Are these just 1/8" AD aluminum rivets, or are they some funky steel rivet? Further thoughts: This looks to be a ripe area for corrosion, with a steel tube, aluminum (assumed) rivets, and rod end bearings that appear to have aluminum shanks. Tony Bingelis in the yellow book (speaking of push pull tube construction) recommends putting primer on the rod end shank before assembly. I'm thinking I should probably do the following: 1. Clean the oil out of the mounting tube using something like Dawn detergent and an appropriately sized bottle brush 2. Using another bottle brush, apply 2-3 coats of primer to the inside of the tube. 3. Apply primer to rod end shank (2-3 coats) 4. Assemble the whole thing with fresh primer on the rod end and on the rivets. +++ #99 Subject: Re: Mounting Rod Ends/ Paint in structural joints From: Carl (bearhawke-) Consider carefully whether you want to have paint be a structural element in load bearing parts! Generally not a good idea to paint surfaces that are then clamped together with some sort of fasteners. The paint will eventually wear down in the joint with vibration and relative motion until the joint is loose. Friction is a significant mechanism in how load is transmitted across a clamped joint. Not designed for but significant in how real joints work. Think about it. I think Bingelis mentions coating the rod end with wet zinc chromate before riveting. You'll end up with metal to metal clamping this way with the zinc chromate just filling the voids and keeping moisture out of the joint. I think there was some talk of painting the elements of the wing spar before riveting together? Bad idea. Zero thickness conversion type coating is okay but paint is a bad idea. Rivet the spar together then paint the assembly If there are no dissimiliar materials then this is plenty good enough. (or do the wet paint thing if you think you can finish the part before the paint sets up!) The wet rivet idea is okay as you are getting metal to metal contact with the wet paint just left filling any voids though probably not worth all the extra mess. Structural joints need metal to metal contact. Paint is not a stuctural material. If you sandwich paint in between the load path then the paint is in the load path and becomes structural! (For further disturbing thoughts, think about the increase in bending stress in an aluminum rivet used to clamp two sheets of aluminum together held apart by a generous coat of paint on each clamping surface. Pure shear in the the rivet becomes shear and bending, yes?) +++ #114 Subject: Re: Mounting Rod Ends From: Mike M. Wow - you guys can go off on the least little thing! As for the attachment of the rod ends let me preface by saying that we are not building a supersonic 25 g fighter jet. The rivets are 1/8" steel or 5/32" aluminum your choice - The rod ends are made from cad plated steel and the tubes are steel so if you wanted to keep everything steel you should go with the steel rivets. As for the painting before assembly - I don't know - all I can do is tell you what Bob said. 1. Before you ream out the hole - paint the inside of the tube with zinc chromate or epoxy primer. The outside should already be painted with a finish coat of epoxy or plated. 2. Ream the hole to fit the rod end that you are using. 3. Fit up the rod ends with the control surfaces in place (sounds difficult but it is a lot of fun) and mark the depth that each rod end will be inserted. 4. Liberaly coat the rod end and the reciving tube with Loc-Tite (Do the best degreasing job here that you have ever done using solvents and not a drop of water) and insert the rod end. 5. You are not riveting at this point - re-assemble the control surfaces to proper alignment and let set overnight. Loc-Tite has a long working time so you do not need to rush. If you screw up you will need to heat up the component with a propane torch or in an oven to pull the rod end out - this will ruin all of you paint job so you want to avoid this if at all possable. 6. If you are satisfied with the fit and alignment of your control surfaces you can remove them and rivet them in place. Bob is the first to admit that this is not a SOP for assembly work on aircraft. It is what we have done for the last three sets of wings that we built. The Loc-Tite forms as a gasket at the end of the rod end on the inside of the tube and also seals the open end. The joint will be air tight and you will not have to worry about corrision it also remains flexable to those parts of itself exposed to open air. Do not use epoxy glues to assemble they will become to brittle. The joint was designed so that the rivets can take almost 150% of the load till failure - everything else is a bonus - so don't worry about it. Just try to keep your slop as little as possable - if you use the reamer correctly your maximum variance will only be .001". I thnk that this is enough on this topic - I am getting a cramp in my hand- If you need more information give us a call and we'll do our best! +++ #116 Subject: Welding Bearing Tubes From: Russ Erb Greetings Bearhawkers! Part of this weekend's task on #164 was to weld on the tubes that carry the flap torque tube. These are on the flap drive and the bracket at the wing root. As is my custom, I'll pass on to you some of the things I've noticed. I welcome any additional comments from any of you who have done these parts or similar welding. First of all, there is one thing missing from the plans. You need to provide for a grease fitting (zerk fitting) on each of these bearing tubes. These are to allow you to grease the bearings just like you do on some cars. You'll also find these fittings on the tail feathers (which are shown in the plans). Bob put these fittings on the prototype--you can see them. I don't know why they didn't make it onto the plans. Bob put them on the bottom of the bearing tubes. This puts them basically flush with the bottom surface of the wing, with the advantage of they can be greased without removing any panels through a hole in the skin. Personally I decided to position them facing forward. This means to grease them requires removal of an access panel, but it leaves the bottom of the wing cleaner aerodynamically with no hole there. The access panel would be there anyway to allow servicing of these parts. So how do you mount a grease fitting? Simply weld a nut on. Now for the details. MS15002-1 Grease Fittings have a 1/4-28 straight thread (AS&S 1998-1999 Catalog page 138) and an effective thread length of 0.075". This means that it will fit into a AN345-428 nut without any sticking out. You'll want to cut the bearing tube (1-1/4" long) and weld the nut on to the center before welding either of the supporting brackets on. You have to weld all the way around the nut to seal it (so that the grease will go where you want it) and the brackets would just be in the way. You'll need the AN345-428 Cad plated nut. Don't get the stainless steel nut because stainless steel has different welding requirements. However, it is absolutely critical that you understand something: HEATING CAD PLATING TO WELDING TEMPERATURES IS HIGHLY TOXIC! TOXIC! THAT'S BAD! (For that matter, heating zinc (galvanized) is toxic too...) [ see welding. ] (For that matter, heating zinc (galvanized) is toxic too...) So what to do? First, sand off as much of the cad plating from the nut as you can. Then take the nuts OUTSIDE and heat them with a torch until they glow red. This will burn off the remaining cadmium. It wouldn't be a bad idea to wear a respirator for this step, although I have no proof that it would guard against this hazard. After cooling, jig the nut in place in the center of the bearing tube. Tack weld in place. Screw a stainless steel bolt (AN4C) into the nut. This helps prevent damage to the threads during welding. Now weld all of the way around the nut. As soon as you're done welding, while it's still hot, remove the bolt. This will prevent it possibly getting stuck as it cools. As a side note, I used stainless hardware to hold the ends of the flap drive and aileron drive in the jig shown in the newsletter. The bottom bolt at the rear end is very close to the weld area, and the head would get red hot while I was welding. After cooling, as I tried to remove the bolt, the nut was jammed on the bolt to the point that the bolt failed in torsion (i.e. broke) as I tried to remove it. I'm not sure what happened, but it happened 3 out of 4 times, so something must be going on. After the assembly cools, drill a #40 hole through the tube in the center of the nut. This lets the grease in. I built a simple jig of wood to hold the flap drive and the root support bracket in the correct relative positions, although little less than 2 feet apart rather than the full distance apart. This was mostly driven by the table space available. Remember the root bracket has 1/8" additional spar thickness at the back! A 3/4" tube was then placed the proper distance above the table to hold the bearing tubes and their brackets in place. However, that bearing tube that fit so nicely over the 3/4" tube before doesn't anymore. Hmmm. You've probably noticed that when you weld a piece, the other side of the metal "bubbles up" and has a rough surface. Normally you like to see that, because that probably means you got good penetration. However, in this case, that roughness is keeping the bearing tube from sliding on. I used a small grinding wheel in a Moto-Tool to smooth it back out so that it would slide on the jig tube. You may have to grind away a little bit of the weld around the nut to get the brackets on the tubes. Put everything together in place in the jig. Now double check to see that everything is in the right place. Screw it up now and you get to remake them later. Tack weld each of the parts. After cooling, remove it from the jig for easier access to finish the welding. This brings me to a discussion of welding tips. That is, tips on tips. I use the Henrob 2000 torch (formerly Dillon torch--that funny pistol grip torch you've seen in the magazines). The smallest tip is size "0" and the tip hole and heat capacity grows with larger numbers. It comes with tips "0", "1", "2", and "3". I also picked up a tip that was a "0" slightly drilled out that I'll refer to as a "1/2". You can only turn the pressure up so much on any given tip to get more heating. After that, you need to go to a bigger tip. If the puddle doesn't form within a reasonable period of time (usually 10 to 20 seconds), you need a bigger tip. If you're welding and the tip starts to pop, that means the tip is getting too hot from being too close to the work. Get a bigger tip. If you can't seem to control the puddle and metal is burning away all around you, your tip is probably too large. Don't fight with it, try a smaller tip. And now for what I learned today: You may find it helpful to change tips while welding on the same piece. On the bearing tube brackets where I had about 1/8 to 3/16 distance to the edges (around the bottom side), I got the best results using my "1/2" tip. When I got around to the top side where the sizable portion of the sheet was, I could no longer maintain a puddle. The filler rod material just sat on the surface and did not penetrate. I changed to the larger "1" tip and everything worked normally again. In general, the more metal around the area you're trying to weld, the bigger tip you'll need because you're heating more metal. On a previous part, I had welded one previously but this one would not form a puddle. I finally figured out that I had a brick next to it holding it in place, and that brick was pulling the heat away from the part. I moved the brick and was able to weld it again. As for the bearing tubes, after the final welding, the Moto-Tool will have to come out again to grind the insides of the tubes. I'm thinking of using a brake cylinder hone from the auto parts store to smooth the inside after grinding. Remember this when you get to the tail feathers. Don't put the bearing (hinge) tubes on the control surface and then weld the bracket on it. I bet it won't work. Weld the bracket on first, clean up the inside, then put it on the control surface. Remember, any friction in the flight control system is bad, so don't intentionally increase it by welding in the wrong order. You won't be able to completely eliminate friction, but you should minimize it the best you can. +++ #122 Subject: Re: Welding Bearing Tubes From: bearhwk27- Nut attachment for the grease fittings is typically by brazing. +++ #125 Subject: Tack welding--a lesson relearned From: Russ Erb I was welding the fairlead holder for the wing root support bracket for the flap torque tube today. As you may know, when we heat metal, it expands. When it melts at the weld puddle, any built up stresses are relieved. Then as it cools, it shrinks, possible distorting the part. I tack welded the two tubes together at two places 180 degrees from each other (opposite sides). I then welded around one side from one tack weld to another. As I said above, this side shrank, and with nothing to oppose it, pulled the tube out of alignment to that side. I welded around the other side, but since the previous weld was there to oppose the shrinking, the tube did not bend back into alignment. (That part is now toast) On the next one, I tack welded it first just like the other piece, then I tacked it half way between, so that I had four tacks 90 degrees apart. The tack weld alone doesn't distort the pieces noticeably, especially if it is still jigged to resist such movement. I then welded one quarter of the way around (between two tacks), then the quarter on the opposite side. Then the remaining two quarters. The tack welds provide resistance against the pieces pulling out of alignment. This method of quarters was suggested in the EAA welding video but they never said why. I think I've rediscovered why. The second piece was completed without noticeable distortion. Anyone else have techniques for minimizing distortion? +++ #126 Subject: Re: Tack welding--a lesson relearned From: Timothy Neil On this particular peice we did just as Russ except we tacked it in three places.We are also using TIG so the heat is concentrated in a smaller area or so it seems. +++ #132 Subject: More Welding Notes, Flap Springs From: Russ Erb One other lesson learned falls in the category of "Learn from other's mistakes--you won't have time to make them all yourself." Pat Fagan wrote that while welding the flap and aileron hinge mounts, he found that they would shrink. Therefore, I built my jig to make the part 1/8" oversize toward the hinge line. Sure enough, the parts shrank about 1/16". When I was done, I trimmed off the excess and had a properly sized part. +++ #140 Subject: Re: Bending Dies From: Float-by Shooter > Pat Fagan sent Bob a picture of a die he used to form the wing > hardware. > > Pat could you describe in a bit more detail how this die is > constructed? How deep is it? How wide and what kind of a radius did > you end up with in the parts? Could you, did you use a similar die > for the rudder/elev hinges? I'm not Pat, but I built a set of dies patterned after the one he used. I placed some pictures on my page at http://www.cordovanet.com/~packrat/planes/bearhawk.html Click on "Project Pictures" and scroll down to see one of the dies in action. Mine differ from Pat's in that I ground a radius into some square stock that was lying around to make the female portion of the die while his used round stock, giving a more generous radius. It probably forms the steel easier than mine. A couple weeks ago I completed another die to form the 90 degree pieces used for the aileron and flap hinges and elsewhere. It works very well and I will try to get some pictures of it soon. I've been wondering about how to form the hinges for the tailfeathers, maybe some kind of rolling fixture would work but would probably be more complex than necessary. +++ #142 Subject: my latest press die From: Float-by Shooter Tonight I got some pictures of my latest press die on my website. This one is also patterned after the one shown in the picture that Pat sent in for the newsletter, but unlike the others it only bends one 90 degree angle at a time. I've been using it to make the bends for the flap and aileron hinges and it has been working extremely well so far. It can be viewed at: http://www.cordovanet.com/~packrat/planes/bearhawk.html Click on "project pictures" and scroll down to the bottom, they are the most recent pictures (maybe I should put those at the top next time...) The die was made primarily from bits of scrap steel that were around the shop, and so far has been working very well. Due to metal springback the pressed pieces are not quite 90 degrees and must be clamped in a vise and smacked with a mallet over a bending block to finish the bend. I didn't build in any allowance for springback since it would have been trial and error, and later I may want to bend something that springs back less than 4130. I hope the pictures are useful to anybody who is thinking of trying something similar. Got my new Bear-Tracks today and will probably be sending pics to Bob also, and try for that hat! +++ #655 Subject: Flap Torque Tube positioning From: Russ Erb I've noticed the plans are not specific about the spanwise location of the horn (arm) at the root end of the flap torque tube (i.e. buttline position). The best I've been able to figure is that the arm, and thus the cable actuating it, should be aligned with the rear spar attach point. My reasoning is that the cable could interfere with the root end of the spar. The greatest clearance would be where the spar and the fuselage attach point form an inverted "V". Hence, that should be the position. Anybody have any better information? +++ #657 Subject: Rubber Baby Buggy Bumpers From: Russ Erb Those of you with far too good of a memory (or just too much brain sludge) will recognize the subject title as the same one I used for basically the same question way back in Feb 1998. The plans for the flap drive call for a "rubber bumper" under the flap pushrod, but is no more specific. In 1998, it was suggested to use a piece of rubber hose, slit and safety wired around the tube. For some reason I got "garden hose" in my head, and spent much time trying to figure out how to get a few inches of hose without destroying an entire garden hose. While looking for another idea, I stumbled upon what I think is the optimum answer. Go to your local auto parts store or hardware store and buy a foot of 3/4" heater hose. This is the hose used in cars to connect the heater cores. It's rubber, it has a good thickness, and it fits around the tube. +++ #739 Subject: Cable Retainers From: Russ Erb As I was looking at the pulley on my aileron drive, I remembered that the plans call for "cable retainers" around the pulley. The only other places I have seen aircraft pulleys were on kit aircraft, and the retainers looked like a manufactured part. For those who may know, are these available somewhere or should we just cut out a little sheet aluminum and make our own? Would .020 be sufficient thickness or would we need thicker? I'm not real sure of the purpose of the cable retainers as long as the flight control cables are in tension--perhaps to keep the cables from falling out during maintenance? +++ #740 Subject: Re: Cable Retainers From: Shelly I would use .40 or .50 - easier to weld and stiff enough to retain the cable. If you can get a glimpse of Christavia or Baby Ace plans, you get a good idea of what they do. The should be pretty acurate so as to retain the cable and not interfere with it. Just bend a strip about .5 in. wide to encompass the pully without interference. +++ #741 Subject: re cable retainers From: stephan pelgar cable retainers are important to have on a aircraft cable system.they are there to make sure that the cable cant accidently come off the cable in flight.true there is cable tension but if there were a peice of something to get on the cable then have it pulled between the cable and the pulley it would cause it to come off.on the large aircraft i work on there only a pin that goes through the 2 plates that the pulley is mounted in between.if the pully is mounted on the bearhawk with one side open then your going to need to put a angle peice of metal that wont bend back easy or a pin that sticks up higher then the pulley.you want the retainers where the cable enters and exits the pulley.if makeing a 90 % bend with cable then have the pins one on each side of the pulley square to the pulleys center.and you want it less then half the cables thickness away from the pulley.this will keep it on the pulley.hopefully this helps some. +++ #743 Subject: Re: Cable retainers From: Bill Cox What Bob shows on drawing 11 is common to ragwing Pipers and others. I would fab it from .032 4130 Sheet. It is held on by the bolt holding the pulley. Some type of tab to prevent it from turning would be desirable. Steven is correct about its purpose. Bolts or rivets are sometimes used, especially in sheet metal structures, but I believe what Bob shows is going work best on most of the BearHawk pulleys. +++ #744 Subject: Re: Cable Retainers From: Shelly > Weld? Where did welding come in here? Did I miss something? The guards must be firmly attached to something rigid!!! How ese would they be able to contain the cable should it decide to come off the pulley? Please try to see some of the afore mentioned plans. It is very easy to understand if you can see it. All early airplanes and all homebuilts use them. +++ #745 Subject: Cable Guides / Retainers From: bearhwk27- A quick trip past a Super Cub or Husky will show you what you need. Look where the front wing strut attaches to the wing. It is all hanging out in the breeze. Easier to make than purchase. +++ #747 Subject: Cable Guides / Retainers From: Russell E. Erb I was discussing cable retainers with the guys in Chapter 1000 tonight. I was wondering why they were there because I was thinking in the static case. The reason for them can be seen in the dynamic case. For one possible scenario, imagine a gust pushes up on an aileron. Conceivably this would stretch the "down" cable, which might be sufficient to allow slack in the "up" cable. If at this point the cable slipped off the pulley, things could get really exciting really quick. Especially if your cables weren't properly tensioned to begin with. For the flaps, pulling down on the flap without using the lever (such as in preflight) will allow slack in the cables. The Chapter meeting tonight was a project tour which included the Bearhawk. Everyone was suitably impressed, with the usual number of people amazed that this is a plans built airplane (some of whom buy airplanes because they don't want to take the time to build a kit). +++ #748 Subject: Re: Cable Guides / Retainers From: Gary Danford The advise on the previous notes is correct, the retainers is only as you have noted to keep the cable on in the event everyting goes slack. The Hatz uses them in several places. They are simply a "U" shape of very thin 4130 that is held in place by the bolt thru the pulley. When you sandwich the mounting bracket + the retainer + the hub of the pulley tight with usually an AN3 or AN4 bolt the retainer can't move. Remember (as I forgot on my Hatz) that every ounce of weight off the airframe is an ounce you can haul. I found that keeping weight off the airframe was far easier than taking it off me. Thus the retainer can be as thin as .020. +++ #750 Subject: Re: Cable Retainers From: Tim Anderson Another option is simular to what is used on float plane water rudders. In fact, if one goes to WWW.airsea1.com (that's a 1 (one), not an I), they have good photoes of pulley brackets and mounting hardware. they use a small cotter pin next to the pulley to keep the cable from slipping out of the pulley. water rudder hardware is stainless steel, so it's a little pricey. I haven't looked at the drawings pertaining to the pulleys, but that may be an option. +++ #1250 Subject: MAKING FITTINGS From: Gary Danford Making Fittings: Under the for what its worth department the below is a method for making fittings. During my first project, I began to hate making fittings. A stone grinder, hand file and hack saw is definitely not the answer. However, recently a friend taught me his method and it works perfectly. With just a little practice, making fittings has become one of the most enjoyable parts of building the Bearhawk. Step 1. Purchase 4130 in 6" inch strips. Its available in various lengths or have it sheared into 6" strips. The 6" strips make slicing of fittings easy with an inexpensive metal cutting band saw. Mine is an old horizontal Sears that is at least 40 years old. Clean all the oil off the steel and spray it with "layout fluid" available in several colors. Layout spray in spray cans is available at any machine shop supply house or from Enco, my favorite supplier. Enco (WWW.use-enco.com) or (1-800-use-enco) has a great free catalog and is an inexpensive source for bits, cutters, belts, counterbores, etc. The layout fluid also serves to protect the metal (since you've taken off the oil) and makes your layout nice and clear. Step 2. Using a scribe and a spring divider transfer the fitting dimensions from the plans to the steel. On some complicated fittings trace the fitting onto a piece of drafting velum. Using masking tape, tape the velum onto the steel and with a spring loaded center punch, punch through the velum at all the line intersections, hole centers, and radius marks. Remove the velum and scribe between the punch marks and scribe the radius patterns and bolt holes with the spring divider. Step 3. With your pattern clearly scribed on the steel, slice off the fitting. Leave an extra 1/4 to 3/8 of an inch around all areas where you have to weld next to an edge. Drill the holes where needed (undersize of course) and debur and ream to the correct dimension. If a weld is required near an edge (reinforcing washer's etc) weld them in place. If a bend is required, make it before final shaping of the fitting. If you are having trouble welding the base next to the edge of the tube bearings on the rudder, elevator, and control sticks, make the tube bearings 3/8" longer on both sides of the base and mill it down to the correct size with an aircraft counterbore. On small tubing like that used on the control stick pivots (3/8 X .058) make it over-length, weld in place and counterbore to the correct fit. If you have weld too close to the edge of a bolt hole you can face it with a small counterbore. The aircraft counterbore's have a 1/4 shank and work perfectly in a drill press at slow speed. The changeable pilots for the large aircraft counterbore may not be available in the correct dimension (7/8 diam x 3/16 shank) but they can be made easily on a lathe. Step 4. Using a belt grinder with a medium to course belt, (prefer a 1X42 with a Zirconia belt (ENCO $1.05 each)) grind the fitting to its final shape. The belts last through at least a dozen fittings and cut faster, smoother, and with less heat than a rotary stone grinder. A 1X42 belt grinder costs around $100.00 and are worth every cent. The flat grinding belts will radius the corners and even make re-enforcing washers perfectly. Be sure and use leather gloves, vice grips, and eye protection. Using belts with different grits, you can get a perfectly smooth edge. I use the 1X42 for course work and have a 1X30 small Dremel belt grinder for the final shaping. A "Scotch-Brite Deburring Wheel" will further polish the edges and you have a great looking fitting. I also use a homemade sand blaster cabinet to remove surface tension, slag, oil, layout dye, and it gives the fitting or part a perfect base for primer. Try it on the control stick fittings, they are a real treat. +++ #1251 Subject: Re: MAKING FITTINGS From: budd davisson Good fitting stuff Gary. And here's anothe FYI for fittings. If I have to make more than one of a particular piece, I rough out blanks to the approximate dimension and stack them up. I clamp them together and tack weld the stack along opposing corners. Do the layout on the top one, drill all your holes through the stack at one time, dress the edges up to the tacks and, when ready, grind the tacks off. Voila four or a dozen identical fittings. +++ #1546 Subject: nutplate source From: Collin Campbell It would appear from looking at the pictures of the fuel tank cover and all the access plates that Bob used recessed screws to hold these on. I am having trouble finding a source for the recessed nutplates that will accommodate a #6 recessed screw. Anyone found a source for these or does someone have a brilliant idea as to modifying a regular nutplate to accept the dimpled surface of the skin? Also does anyone know the difference between the AN366 anchor nuts specified in the plans for the aileron/flap hinge and a K1000 all metal anchor nut. BIG difference in price, I am assuming the AN366 must be more structural in this area, but would work on access plates, etc. +++ #1549 Subject: nutplate source From: Russ Erb > It would appear from looking at the pictures of the fuel tank cover > and all the access plates that Bob used recessed screws to hold these > on. I am having trouble finding a source for the recessed nutplates > that will accommodate a #6 recessed screw. Anyone found a source for > these or does someone have a brilliant idea as to modifying a regular > nutplate to accept the dimpled surface of the skin? > > Also does anyone know the difference between the AN366 anchor nuts > specified in the plans for the aileron/flap hinge and a K1000 all > metal anchor nut. Yea, about $4.17 a piece! I have a picture here taken by Pat Fagan (part of the "lost" set recently found that didn't make the CD, see it in Version 2 someday) of the inside of the access panel to the flight control pulley at the strut junction in Proto II. Very obvious that Bob is using the K1000 nuts. I've use a bunch of them too. Order yourself some K1000 anchor nuts (they're cheap, so just do it). You'll find that the portion of the nut that goes against the skin has a small recessed area that will accept part of a countersink or dimple. I haven't tried it specifically, but I have put a countersunk screw into one and the head went a ways into it. It's hard to describe--just order some and see for yourself. I also just realized that all of the aluminum parts in this picture (spar, rib, skin, access door) are primed! Corrosion control after all! +++ #1578 Subject: Re: nutplate source From: pfflyer- I got this information from Bob himself. He used the K1000 net plates on his fuel tank cover. He didn't bother with dimpled nut plates, too expensive, but rather countersunk the backing plates. I did this and noticed that the flush screw head still protruded slightly from the dimpled skin. To solve that, Bob said countersink a hole in a piece of steel, then insert a screw in the dimpled skin hole and into the countersunk hole and tap it with a mallet, which works to make a perfectly flush screw head. In the same vein, I had purchased a whole bunch of cad screws for all my access panels, then discovered that the K1000 net plates are so tight that I would usually ruin the screw head installing and removing the screws. I sent them all back and paid the few extra cents for stainless steel. They go in and out without any problem, the only problem is holding on to the tiny screw without the aid of a magnetic screwdirver. +++ #1954 From: Russ Erb Subject: [Bearhawk] Nutplate mania Some thoughts on nutplates and access covers. If this isn't new to you, well, I posted it before you did... A very definite way to get MVP (major visual progress) on your project is to skin the wings. Of course, after doing a wonderful job of getting the skins on just so and drilled with no (well, okay, very few) mistakes, it is easy to admire your work. But then the next step is counterintuitive--you have to start cutting holes into that beautiful skin for access covers. From looking at drawing #2, it appears that Bob has suggested that the backup plates for attaching the access covers be 3/4" wide, leaving 3/8" for riveting and 3/8" for attaching the nutplates. I've decided to use the F5000 all metal floating anchor nuts instead of the K1000 anchor nuts on my access panels because the floating nutplate is slightly more tolerant of misalignments, which is more likely on a somewhat flexible piece. For these nutplates, a width of 1/2" was more comfortable, and I felt more comfortable with edge distance and such using 1/2" wide for the riveting half. Therefore my backup plates in general will be 1" wide. If we were using round headed (or truss headed) machine screws to hold on our access panels, installing the nutplate would be easy. Of course, what's the point of using round headed screws after going to all of the trouble to use countersunk rivets? So, we want to use countersunk #6 machine screws to hold the access covers on. Well, .025 skin is way to thin to countersink for a #6 screw head. So what do we do? Same thing we did with the rivets. Avery sells dimple dies for #6, #8, and #10 screws. You'll also need different drill bits--I think I ordered 9/64" for the #6 screws and 11/64" for the #8 screws (3/16" still works for #10, which are the same size as AN3 bolts). Great, so I dimpled the access cover for the screw. Now it won't sit flat on the backup plate. Hmmm...what did I do before...oh, yes, simply dimple the backup plate too. No problem. No (comma) problem. Now the nutplate won't sit flat on the backup plate because of the dimple. Hmmm... Usually we countersink for the rivets holding a nutplate so that the dimples for the rivets don't raise the nutplate off of the piece it is attached to. However, in this case, we can use this to our advantage. If we simply dimple the holes for the nutplate rivets, it all works out to where that is just enough to fill the gap between the nutplate and the backup plate. How slick. So to review, dimple the hole for the machine screw in both pieces, and dimple for the rivets holding the nutplate, and it all works out. I recommend you try it on some scrap pieces just to convince yourself. Oh, and be sure to count up how many nutplates you'll need. If you're like me, just the ones around the fuel tank bay will amount to about 3 times more than what you guessed you would need! +++ #2160 From: William & Delinda Johnson Subject: Rod Ends - $12.00 Each at AT2 Surplus I found some rod ends at Sun & Fun for $12.00 each. Talked to the surplus dealer (Russell). He has about 1000 more of these jewels. The part number on the rod end is RE4H6-2 made by Fafnir (look at the Spruce catalog and you will see these are the right ones). If you would like to purchase, fax an order to Russell AT2 Surplus (847-432-6847). He said it takes time for him to fill orders so be patient. +++ #2236 From: bearhwk272 Subject: Flap and Ailerons Seeking info On the flap and aileron attachment at the .063 doubler..... where the rivets go thru the spar, doubler, and nut plates is the correct method to dimple the .032 spar and countersink the .063 doubler? Did you countersink the sandwich and let it go at that because it is a bolted assy? +++ #2241 From: Russ Erb Date: Sat Apr 22, 2000 2:49pm Subject: [Bearhawk] Flap and Ailerons Kevin-- I hadn't thought about it before/recently, but I would have to say that I will countersink the sandwich. The rivets in the nutplate don't carry much load, just the torque of the bolt. Additionally, the bolt carries a larger load that keeps everything smashed together. The doubler is held to the spar by the rivets holding the ribs on. My flaps and ailerons are assembled, but I haven't drilled those holes yet. I wanted to drill them on assembly to make sure everything was lined up. Strictly speaking, nutplates are not required there. You "could" bolt the pieces in place before covering. If they never loosen up or need removal, you're okay. However...I'd hate to recover and repaint just to tighten a bolt. I plan to install nutplates myself. +++ #2465 From: William & Delinda Johnson Subject: Aileron Pully Misalignment Russ and others who have built their wings, was the misalignment of the aileron pulleys in the vertical or forward/aft direction. In looking at the plans, it appears that the alignment problem is for/aft and modification of the bracket holding the pulley at the strut area is all that is necessary. (appears that the strut area pulley top is about 1/2 inch too far forward) I ask because the information on the CD leaves me confused. One person said the cable changes vertical height from the strut pulley to the support frame pulley - I don't see that. Another posting seems to indicate a slight misalignment correctable with by clamping the strut pulley bracket to a bench and hitting with a big hammer. That indicates a forward/aft alignment problem (that is what I see on the plans). Bob said in a newsletter he would post a fix to Beartracks but I can't find the fix. So, please provide guidance. +++ #2466 From: Russ Erb Subject: [Bearhawk] Aileron Pully Misalignment I do remember there was a slight misalignment. Seems like the pulley was "twisted" slightly in respect to the cable. I don't remember exactly, but it seems like I built the bracket per the plans, which shows basically two-dimensional bends. After installation, I used a big crescent wrench to twist the center section to where it needed to be. That would be my recommendation--build per plan, then adjust slightly as required. Boy, I hope no one asks questions about how I did the ribs--I've probably forgotten most of that by now! +++ #2473 pfflyerz Subject: Re: [Bearhawk] Aileron Pully Misalignment I may have been the first to bring this pulley alignment to the groups attention. When I asked Bob about it, he admitted his cables ran slightly askew on the pulley, but he hadn't noticed any wear yet. He felt it could be built as per plans, but also felt that one of the attachment holes could be drilled in a slightly different position. That was the quick fix he mentioned in the news letter, but I don't remember what hole need ed to be repositioned. What I did on mine was weld another piece of .062 steel to the top of the bracket, then belt sanded a bevel perpendicular to the main axis of the bracket. After trial and error and several fit-ups, I got the cable running true over the pulley, then drilled the pulley bolt hole at the finished angle and beveled the lower .062 doubler to match. Seemed to be any easy fix, especially since my holes had already been drilled in the spars per plans. I now understand why all you floaters are so interested in building your own floats. I had no idea floats, especially amphibious floats, were so ridiculously expensive. Will know Wednesday if I was succesful in bidding for this salvage. If so, I will have a pair of amphibious floats for sale to recoup my investment. One other side note for all you folks just getting started; Bob recommends that you start on the wings first and from my experience, that is a darn good idea. There is so much work in the wings, it is a good place to determine if you have the patience to construct the entire airplane. By contrast, the tube structure goes together so quickly, and is so rewarding, it could give you a false sense of progress if you start right in with it. Just my two cents worth. +++ #2587 William & Delinda Johnson Subject: 023 Update I have been busy building; however, as hard as I have tried to remain unemployed, I took a new job which started last week. Once again, the Bearhawk is only a 35hour a week project. But I am determined to finish this year. The web site has been updated (press refresh on your web browsers to get latest) with detailed pictures of the wing support (drive linkage) construction, firewall layout, and rib flange bending. I also added a spar overview picture. Notes: 1. I built the support frames from the rear forward to account for shrinkage. You will see what I mean as you look at the pictures. In other words, the last pieces welded were the front spar attach fittings. I also drilled holes in the end of the spar attach fittings to make welding easy and clean. Bending Jigs are not necessary as a good bending block works fine. Overview of completed frames: http://home.fuse.net/wjohnson/wcsf132.jpg 2. Painting - All parts are cleaned with PPG DX330 wax and grease remover, etched with PPG DX 533 aluminum cleaner (I use aluminum cleaner even on the 4130), and cleaned again with PPGDX330. Aluminum parts are conditioned with DX503 and zinc cromated. 4130 parts are sprayed with PPG epoxy primer (see picture above). +++ #2646 From: Barry Schutt Subject: Flap return springs OK, I've looked at the drawing and read the newsletter and am still not sure exactly what size springs I need. The plans call for 1/2" 20# and the drawing scales out to about 10 inches long plus some for attachment. The question is what does the 20# mean---- is that 20 pounds per inch load to strecth the spring, do I pretension it to 20 pounds ? Springs sted to be somewhat non-linear over a long extension but are almost linear over a very short extension. I've found 1/2 inch dia .054 wire door springs 8 inches long which wouldn't give enough length to stretch or 9/16 springs 15 inches long, which can be cut down to length or do I keep looking, can we use a variation or is the exact size real important? In general the springs I've found are not labeled with a # rating only OD and wire size----HELP!!!!!! +++ #2654 From: Bill Cox Subject: Re: [Bearhawk] Flap return springs Barry, I recently made the flap return springs from the 9/16 X 15" door springs. A week on so later I was reviewing Russ CD and he described the process I used. I'm fairly sure Bob made his the same way. +++ #2655 Russ Erb Subject: [Bearhawk] Flap return springs > OK, I've looked at the drawing and read the newsletter and am > still not sure exactly what size springs I need. Short answer: Use screen door springs from your local home mega-warehouse modified to suit. Pictures of how I did it are on the Bearhawk CD. Nobody has been able to come up with a good answer as to what the "20#" means. It's definitely not a spring constant of 20 lbs per inch. Remember that the primary purpose of the springs is to hold the flaps up on the ground. In flight the air loads keep them up. From Bear-Tracks: FLAP SPRINGS - Use heavy duty screen door springs 9/16" O.D. and straighten out a few of the coils on each end to form the required hook ends for the proper configuration. +++ #2712 From: Subject: Re: [Bearhawk] Spar End Plates I asked Bob the other day if there are any high strength or close tolerance bolts called for in the airplane and he said "no". For those who have never spoken with Bob, he's not one to just carry on endlessly. Thanks Budd and Bill for the welding info. Anxiuosly looking forward to welding up the fuselage, but those summer activities keep getting in the way. My wife is dragging me to the Colorado River for three days and won't let me do anything but read and sleep in the boat. Alas, poor me. +++ #3138 Subject: Fine/Coarse/What's the diff? From: Russ Erb I hate it when that happens! I spent tonight putting fiber-lock nuts on some 10-32 machine screws holding a wiring conduit in place in my wing. These nuts are difficult but not impossible to put on. I accepted that these would be difficult to put on for various reasons, including that they would be put on once and then never touched again. In fact, after attaching the bottom skin, many of them will be inaccessible without cutting new access holes. Anyway, after putting on two, I struggled with one that wouldn't seem to go on. I decided that the machine screw had become cross threaded and would have to be removed and replaced. Of course, this was quite difficult and took about 30 to 45 minutes. After getting the new machine screw in, I did a trial fit of the nut on a similar screw straight out of the bag. Same problem. Hmmm. Tried several other nuts. Some went on easily, some wouldn't go on at all. Closer inspection revealed the real problem--while all of the nuts were #10, some were coarse thread and some were fine thread! I can't remember the details, but I suspect the nuts were from different sources which got thrown together a long time ago because I had no reason to think they were different. I don't know why I would have ever bought coarse thread fiber-lock nuts--perhaps they came as hardware with a "some assembly required" object I bought in the past. What always bugs me the most about doing things like this is the time lost applying the wrong solution... Russ "Confession is good for the Soul...or...Don't repeat my silly mistakes" Erb +++ #3139 Subject: Re: [Bearhawk] Fine/Coarse/What's the diff? From: Donald Schindler supERBMAN, Fine is suppossed to be stronger in tension(and maybe shear) I think. When I get to the point you are with stuff like suspending harnesses, Im gonna give CLICK-BOND a try, you know the epoxied on fasteners. Their always at every airshow and now all the major airlines are using them. Saves alot of holes drilled in the structure. If anyone has any experience with them Id like to hear it. Soldier On.... +++ #3143 Subject: Re: [Bearhawk] Fine/Coarse/What's the diff? From: mailstuff Stick with aircraft hardware and you won't have that problem! +++ #3145 Subject: Not another Erbman story of frustration! From: Russ Erb Yes, it's true. I share my experiences in hopes that it will help someone learn from my mistakes, since you won't have time to make them all yourself. Today's task was to make the straps to install the fuel tank in the wing. Let me say here that I finally did get it done successfully, but of course not without some buffoonery. (I used to think that I could not successfully complete any mechanical repair (car, lawnmower, whatever) without injuring myself (scratches, smashed thumbs, etc) at least once). The tank fits nicely, but again with rather close tolerances. Since I like to think ahead, I installed nutplates on the front of the spar to receive the bolts holding the fuel tank support straps. Eventually I would figure out one of these nutplates was not precisely aligned with the bolt hole. What eventually led me to this conclusion was the result of trying to insert a bolt (AN3) into the nutplate. I could tell with a mirror that the bolt still had plenty of threads to go, but it was getting hard to turn. Using the "more power" paradigm, I continued to crank it with a ratchet. Well, this bolt was drilled at the end for a castle nut, not because I needed it, but because it was what was available. I figured I would put in an undrilled bolt later. As things got tighter, the bolt broke at the hole, leaving the end of the bolt in the nutplate. Note: Realize this nutplate is in the nose section of the wing, of which the skin has already been riveted on, so it is not exactly accessible. Auuugh! After a few attempts to get the bolt end out (which didn't work) I decided that I had to drill out the nutplate rivets and remove the nutplate. I did that, and realizing what I thought was the real problem, drilled the bolt hole out to 1/64" greater diameter. Reinstalling the nutplate resulted in an "adequate" installation. With no good way to get a bucking bar in there and driving rivets through a 1/2" of cap strips, the shop heads on the rivets are far from MIL-SPEC. In fact, they're barely smooshed or bent as it is. Even so, they won't fall out and they won't let the nutplate turn, which is the basic requirements for nutplate rivets. Point to learn: When using nutplates, especially when using the non-floating kind, be sure that the bolt can be inserted properly while the nutplate is still accessible. ( I had actually tested this, but apparently not well enough.) Enough of this. +++ #3146 Subject: Re: [Bearhawk] Not another Erbman story of frustration! From: Bruce A. Frank This is one of the places that a pulled (pop) rivet would be perfect for the job. +++ #3147 Subject: Re: [Bearhawk] Not another Erbman story of frustration! From: Russ Erb An interesting thought, but a quick check of the Spruce catalog doesn't show a blind rivet of the appropriate size (3/32 for the nutplate) and a grip range of at least 0.625. Even so, I'm not predisposed to thinking blind rivets. I'll have to remember that option in the future. +++ #3148 Subject: Re: [Bearhawk] Not another Erbman story of frustration! From: Robert Hughes Cherry makes a 3/32 steel pulled rivet designed for mounting nutplates. CCR264SS3-1 thru 3-4 is FLUSH head (3-1 grip range is .02 to.062, 3-2 is .063 to .125, 3-3 is.126 to .187, 3-4 is .188 to .250) CCR274SS3-1 thru 3-4 is the UNIVERSAL head version Rich Industries 800-240-2777 (usually excellent prices/ service) or Advance Enterprises 1-800-676-7305 Fax 816-452-7306 +++ #3149 Subject: Re: [Bearhawk] Not another Erbman story of frustration! From: Robert Hughes Sorry Russ, I just re-read your post and realized you were talking .625 instead of .0625.... don't know who makes 'em that long.. the 3-8 size only goes to a grip limit of .500. +++ #3188 Subject: Quarter-Turn Fasteners From: Russ Erb Looking in the Spruce catalog, there are at least 3 types of quarter-turn fasteners: Camlocks, Dzus, and Southco. However, there is no information on how to use them or install them. I wouldn't even know how to order parts. Can someone recommend a reference on how to install these fasteners? +++ #3190 Subject: Re: [Bearhawk] Quarter-Turn Fasteners From: Bion Rogers This is all I could find on the net: First the Dzuz Homepage. http://www.dzus.com/default.html Second, The Southco homepage. http://www.southco.com/ I could not find anything on the Camlock brand name. I hope it helps. +++ #3191 Subject: [Bearhawk] Quarter-Turn Fasteners From: Robert L. Thomasson According to Carroll Smith, the Dzus Fastener Co. publishes an 82 page catalog with installation instructions. Dzus Fastener Co. 425 Union Blvd. West Islip, NY 11795 Smith has three books out, Engineer to Win, Nuts, Bolts, Fasteners and Plumbing Handbook and Prepare to Win. All three are intended for race car builders but belong on an aircraft builders shelf alongside Bingelis' books. I got my Smith books years ago from Motorbooks, Osceola, WI, but they are probably available thru BN or Amazon these days. The Fasteners Handbook covers Dzus fastener installation, but not in depth, as he recommends getting the Dzus catalog. He also mentions some pros and cons between Camloc and Dzus products. +++ #3192 Subject: Re: [Bearhawk] Quarter-Turn Fasteners From: dmccarroll1 Russ, The Dzus and Camlocks are not that hard to install. You can buy tools for the purpose, but rather than spend money, I use an A&P technique that I have been taught. After drilling the receptacle holes and riviting the springs or receptacles in place, I take the panel with the fastners, put the outside face down on a flat surface. I slide the fastner throught the hole and then I snap the retainer ring in place with a properly sized deep socket and soft hammer. It works and saves money in the meantime. My wife being a bean counter, the latter is most important. (Getting funding for building an airplane was like getting a congressional appropriations bill passed). +++ #3193 Subject: Re: [Bearhawk] Quarter-Turn Fasteners From: Shelly You don't need a reference. I have used Camlocks on my last five projects. It's nice to have a plier to install them, but you can make one, or, no doubt, someone in your chapter has one. They are easy to install, very effective, easy to replace (when necessary, which is not often) and easy to manipulate when opening. Used it on Hiperbipe, Hatz, Christavia, Mountain Goat, and Baby Ace. Just buy a couple, (they are cheap) and play with them. +++ #3196 Subject: Re: [Bearhawk] Quarter-Turn Fasteners From: Russ Erb I guess I wasn't real clear on the initial question. The catalog lists a whole bunch of different parts that are available, but doesn't show how they all go together so that I would know what I needed to order. After talking with several people, it seems the answer is to find an airplane with said fasteners and study the installation. +++ #3197 Subject: Re: [Bearhawk] Quarter-Turn Fasteners From: The Aircraft Spruce catalog has a pretty good explaination of what parts are needed & how to figure lengths for various fasteners. +++ #3316 Subject: Wing Iron Question and #433 update From: Doug Knight On Dwg. #11 the bell crank has (2)bearings listed as part (MRC R-4FF), what's the source as their are not listed in any of my aircraft catalogs? Has any body tried to use an oilite bronze bushings for for the flap torque tube at the flap arm mount and at the support assembly at the the wing root? Requires a larger receiver tube to accommodate the bearing and some machining will be will be required, there is room there and a slight weight penalty. #433 is progressing quite well, I lost July doing a major overhaul on my BMW. I promised myself no new transportation till after my bird is flying. All my ribs are rough flanged and I'm in the process of fluting and straightening. Made a custom 7/8" wide set a seaming pliers like the Avery kind, easier with the 1 1/2" rivet spacing. Aluminum Notes for those who want to get started, ribs required 28' of .025 and 4' of .032. That included a losing 9 nose ribs and redoing them. I first ordered 36' of .025" and 12' of .032". When you get well in the the pile-O-parts will have a good handle on what other aluminum to order. +++ #3317 Subject: Re: [Bearhawk] Wing Iron Question and #433 update From: Float-By Shooter > On Dwg. #11 the bell crank has (2)bearings listed as part (MRC > R-4FF), what's the source as their are not listed in any of my > aircraft catalogs? Motion Industries had them for $7.04 each when I checked back in February, but I never got around to ordering them yet. Their number is (205)251-7522. +++ #3323 Subject: Re: [Bearhawk] Wing Iron Question and #433 update From: Wicks has the bearing yr. 2000 cat. page 154 Radial ball bearing "as used on Bearhawk". They are 9.70 ea. I have them on my list of things to order. +++ #3324 Subject: [Bearhawk] Wing Iron Question and #433 update From: Russ Erb > On Dwg. #11 the bell crank has (2)bearings listed as part (MRC > R-4FF), what's the source as their are not listed in any of my > aircraft catalogs? > > Has any body tried to use an oilite bronze bushings for for the > flap torque tube at the flap arm mount and at the support assembly > at the the wing root? Requires a larger receiver tube to > accommodate the bearing and some machining will be will be > required, there is room there and a slight weight penalty. I got the aileron bearings from Motion Industries. They have a local storefront here that I picked them up from. As for oilite bronze bushings on the flap torque tube, my opinion is that would be serious overkill. First of all, you should know that "common" knowledge is that you need a grease fitting (zerk fitting) on each of the flap torque tube "bearings" (hey, it is strictly speaking a plain bearing). This was done on both prototypes. To do this, weld a nut on the outside of the bearing and drill a hole through the bearing inside of the nut. Screw grease fitting in. In service, these bearings (and more on the tail and other locations) will need to be lubed, just like an older car chassis. Probably at least at every annual inspection if not more often. It's all shown on the Bearhawk CD. (info at http://www.eaa1000.av.org/pix/erbpix/bearhawkcd.htm if you're not familiar) I will be the first in line (after budd davisson) to tell you that you want to eliminate as much friction as possible in the primary flight controls (elevator, aileron, rudder). While it is true that a small amount of friction and breakout is needed for good handling qualities, I feel confident that if you do your best to eliminate all friction, you'll end up with enough left over if not still more than you'd like. The trim system is at the other end of the spectrum. You want sufficient friction in that system that it will stay where you put it. Bob and Mike haven't told us yet how they accomplished that. In between are the secondary flight controls, such as the flaps. Excess friction in the flap system will mostly just make you pull harder to put the flaps down, and if excessive might interfere with them coming back up. With the stated greased bearings, this should not be a problem. Remember that the torque tube only turns about 90 degrees in the bearing. It is not a shaft which is continuously spinning. Thus, my opinion of oilite bronze bushings in this location is that it would not be worth the trouble. You might be able to make a better case for using them in the control sticks, rudder pedals, or elevator or rudder hinges. Even so, I think the greased plain bearings will be sufficient. I'm going to need a page in my POH to remind me where all of the grease fittings will be. Bill Johnson has shown oiling holes on his rudder pedals and control sticks. I was thinking of using grease fittings in those locations as well. Comments, Bill? +++ #3326 Subject: RE: [Bearhawk] Wing Iron Question and #433 update From: William & Delinda Johnson Hmmm, I would say that fittings on the rudder pedals might be overkill. Just use a lightweight oil at every annual. After about 10,000 hours they may show some wear . . . +++ #3365 Subject: Real Work.... From: Steve Eldredge Just a status report: Mike and I (Steve) spent all afternoon Labor day cutting out all the patterns for the steel parts in the whole airframe. While I think Charles W. at Dillsburg thinks I am a nut for ordering so many short pieces of tubing, and steel sheet, we decided we couldn't afford the whole Steel order. It should arrive here this week, and by the weekend we will be cutting steel in a substantial way. Figuring bend radius and allowance for the formed steel parts took an hour or two too understand, and then lay out, but we now have all the patterns on 1/8" plywood backed photo copies. This has worked out so far with the following procedure: 1) Photocopy the sections of plans that show the full size fittings, 2a) Cut them out and attach to a piece of 1/8" ply with 3M contact cement, 2b) Allow for setback and bending allowance for bent fittings, 3) Zip out the part on a bandsaw and finish with a bench mount belt sander, 4) Mark the name, size and quantity of the parts on the plywood blank, 5) Layout and outline the correct number of parts on the sheet stock, 6) Cut out steel blanks and finish the edges, 7) Bend, drill finishing touches on the steel parts. Interested if there in other ways to do this part... +++ #3371 Subject: [Bearhawk] Real Work.... From: Russ Erb Steve--glad to hear you're making some progress. Two things: 1. After photocopying the plans, lay the photocopy on the plans to ensure they are identical. Many photocopiers will change the size slightly if not tweaked, or worse, distort slightly. Blueprints are printed in a contact process that avoids this problem. 2. Since I am not tooling up for production, I use spray adhesive to attach the patterns directly to the material. It pulls off later (sometimes sooner, especially if the part gets hot), and the glue residue comes off with acetone. Let us know how the steel forming goes! +++ #3376 Subject: Re: [Bearhawk] Real Work.... From: I just finished, making the last of the steel fittings. Final ones were the redesigned control stick towers, interesting pieces that turned out quite nice. I've gotten pretty good at making fittings by using mostly the same processes. Zerox the part off the plans and trace around the paper pattern on the steel. Rough cut on the band saw then stack the parts in a vice and dress the edges with a 6 inch air grinder. Finish the edges with file and belt sander. For U-shaped fittings, I draw the lines where I want the bend, then stack up steel bars ,with a proper bend redius filed in them, to equal the dimension of the U and align with the lines. Put it in the vice and bend away. No worrying about setback or bend allowance, and I end up with a perfect dimension every time. Mark out and drill the holes. For all those little reinforcement washers I use this technique: Drill a 9/64 hole in the part, great for using up all those little pieces of scrap left from band sawing. Stack all the pieces on a # 8 screw and grind until aproximately round on the bench grinder. Chuck the screw stack in the drill press and, lightly, run the 6 inch air grinder against the spinning stack. By going lightly, the stack will come into round, at which time you can take a heavier cut to get to dimension. Finish with a file, quick and easy. Awaiting a shipment from Dillsburg, then all these parts are going on the fuselage. +++ #3377 Subject: RE: [Bearhawk] Real Work.... From: Steve Eldredge <<>> Question about the following: For U-shaped fittings, I draw the lines where I want the bend, then stack up steel bars ,with a proper bend redius filed in them, to equal the dimension of the U and align with the lines. Put it in the vice and bend away. No worrying about setback or bend allowance, and I end up with a perfect dimension every time. Am I visualizing correctly? First bend of the "U" legs then stack you steel bars and bend the remaining leg? Pat, Great idea about the "washers" +++ #3380 Subject: Re:Making Flat fittings From: budd davisson Yet another idea for making fittings. Here's what I do when I have to make more than one copy of a particular flat fitting (don't they always come in at least pairs?) 1. rough cut some squares that will barely hold the part. Being precise doesn't count or matter. 2. stack them up (I've done as many as ten at once) 3. run a weld bead down each corner of the stack holding it together. 4. glue the pattern to the top of the stack. 5.drill all the holes (undersized usually) 6. Bandsaw to shape being careful to leave at least two of the welded corners until the very last cuts. 7. put two bolts through holes and hog down tight holding stack together. 8. cut off welded corners 9. Belt sand edges as a stack 10. Break them apart and slack-belt sand the edges for roundness. Sounds long, but it's not and it gives you identical fittings every time. The biggest drawback is that if you screw up, all of them are screwed up. +++ #3386 Subject: Today's Topic: Rivnuts From: Russ Erb As you may recall from our previous discussions, instead of pop riveting on the covers over the aileron and flap hinges, I'm using #6 machine screws so that they would be easier to remove for inspection. Since the other side of the screw would be inaccessible, I am installing Rivnuts. Since nobody including Tony has ever seemed to write about them, I thought I would share what I've learned so far. What Is a Rivnut? A rivnut is used to secure a machine screw or bolt. It is permanently installed in a structure and the screw is twisted into it, similar to a nut plate. The Rivnut is installed through a hole, then pulled in a similar fashion to blind rivets to upset the Rivnut to hold it in place. It has the same advantage that blind rivets do, namely that it can be installed with access to only one side of a part. Why Use a Rivnut? First of all, a Rivnut should be your third choice for securing a bolt or machine screw. Your first two choices are a nut of some form or a nutplate. If both sides of the bolt/screw are accessible, the nut may be your best choice. If access will be a problem, then install a nutplate. A nutplate is far superior to a Rivnut in its ability to resist the torque when tightening the screw, because the nutplate has a significant moment arm to two rivets. A Rivnut relies on friction and possibly a keyway to resist torque, and could possibly start turning in its hole, making it impossible to loosen or tighten the screw, especially after a lot of use. Nutplates usually have a self-locking feature, while Rivnuts do not. A nutplate requires installation while its location is accessible. I'm using Rivnuts on the flaps and ailerons because I no longer have access to the back side of the holes. Rivnut Types Per the Aircraft Spruce catalog, Rivnuts are available in 6-32, 8-32, and 10-32 thread sizes. A typical designation would be A6K-75, which breaks down to A - No apparent significance 6 - size of thread. 6 = 6-32, 8 = 8-32, 10 = 10-32 K - keyed. If not present, keyless -75 - Length of maximum grip. For flat head rivnuts, -75 has a grip range of .010 to .075. -120 from .075 to .120 Rivnuts come with flat heads or countersunk heads. The flat head sits on top of the piece, sticking up about 0.032. The countersunk head is countersunk into the part, similar to an AN-426 rivet, such that the head of the Rivnut is flush with the surface. Both Rivnut types accept the truss-head screws (round head). Neither will accept a countersunk head screw unless the overlying part is thick enough to absorb the head. If possible, you should use the keyed Rivnut. This has an extra protrusion below the head that fits into a slot on the side of the installation hole, and gives some mechanical resistance to torque. Rivnuts are not self locking, so you may want to consider use of some loc-tite on the screws. Installation Tools Reading the Aircraft Spruce catalog leads you to think that you need a special tool to install Rivnuts. The catalog choices are: 1. Combination Rivet-Rivnut Tool $214.95 2. L-6000 Rivnut Speed Driver $95 (L-7000 $98.50), each size head $20.95 to $37.95 3. L-845 Economy Rivnut Tool $32.95 4. L-1000 Economy Hand Rivnut Tool $26.25 to $30.95 5. Rivet Conversion Kit $11.50 The last one sounds interesting, described as "Converts you conventional hand pop riveter into an economical Rivnut installer tool." Sounds like something that would last the life of the airplane. I was convinced, so I ordered one. What I got looked like a piece of steel rod (like a nail) that was threaded at one end and the remainder of the rod was turned down to the minor diameter (like we talked about doing for the tail wires). For some odd reason, there were 5 keyless rivnuts included in this "kit." I started to get concerned remembering my experiences with Pop-Rivet tool dimplers. These come with a supply of nails for pulling the dies, because each time you use it, the jaws of the rivet puller dig a little deeper into the nail, until the nail's diameter is reduced to the point where it breaks. The solution--get another nail. They're cheap and available at the hardware store. But for $11.50, I figured this tool must be hardened or something. Nope. When I tried it, the rivet puller jaws dug into it just like they did on the nails. Besides that, it should have been about 1/2" longer, because the jaws only grabbed the last 1/4" of the tool, which is not the complete jaw. I think I figured out why there were 5 Rivnuts with the tool. Because that was about how many I pulled before the end of the tool was chewed up enough that the rivet puller wouldn't hang on to it anymore. Apparently it was only supposed to last long enough to pull the Rivnuts that came with it. So what to do? By now I had seen enough to have an idea. I went to the hardware store and paid $1.19 for 3 feet of 6-32 all-thread (threaded rod). I figured even if each piece only lasted a few Rivnuts, I could make about 12 pullers way cheaper than the one I bought. To make the tool, cut off 3" of all-thread and chuck 1/2" into your drill press. Turn on the drill press and file down all but the last 3/8" of the thread. This is so that the rod will fit into your blind rivet puller tool. For 6-32, it may fit into your rivet puller even without filing. Take it out and cut off the part that was in the chuck. Strangely enough, the thread somehow interacts with the serrated jaws of the rivet puller such that it doesn't tear up the rod as quick. I've made one so far and it's lasted far longer than the one I bought. Installation Technique The A6K-75 that I am using requires a 3/16" hole. Don't drill it with a 3/16" twist drill bit, as the hole will probably be more triangular than round in thin sheet. Drill the hole undersize and then ream it out or use a Unibit. The Rivnut needs a good quality round hole to work properly. For the keyway, I used the edge of a file from the Avery Swiss Pattern Needle File Set. I had originally ordered a $95 tool from Spruce to cut the keyway, but it had been discontinued. The file works reasonably well. To install the Rivnut, screw your tool into the Rivnut until the end is even with the end of the Rivnut (using all of the threads). Insert in hole (with key in slot). Put your blind rivet puller tool on it (recommend using the hand tool here, not a pneumatic one which would probably pull too hard). Squeeze the handle like you're pulling a Pop rivet. Note that it will take a higher force initially to start the upset, then the force required will diminish. When fully upset, the required force will go back up. Don't pull too hard or you may pull the threads out. It took only one squeeze on my puller. Remove rivet puller and grab the rod in the Rivnut with pliers. Using the pliers, start to unthread the rod. After getting it started, the rod should unthread the rest of the way with your fingers. That's all there is to it! +++ #3387 Subject: Re: [Bearhawk] Real Work.... From: Easiest way to picture it would be to imagine you want a U channel with a 1 inch inside dimension. Take a 1 inch steel bar and file a bend radius on the edges. Draw lines on the part where you want the bottom of the U to be and just lay the bar between the lines. Stick it in the vice and bend one side, flip it over and bend the other. For other sized U's, just stack up some strips of .032 or .063 to reach the dimension you want. After bending parts this way, I came to realize that you can make single bends the same way, with pretty good accuracy. Place the part and a bar lightly in the vice, then sight along the top of the bar and adjust the part until the line touches the bar just where it does when bending a U channel. Cinch it down and bend away. The only trick is deciding which side of the bend you want the radius on. When bending things this way, I always drill my holes last, so I can be sure they end up where I want them. I don't remember how the plans call out dimensions for the wing fittings, made them a few years ago with the press die shown in Beartracks. This technique worked really well for making the landing gear fittings, main spar attach fittings and rudder and control stick fittings. In most of those cases, Bob called out an inner dimension, regardless of whether he showed radius or not. For the tapered fittings, I simply bent on the bend line shown on the plans. +++ #3388 Subject: Re: [Bearhawk] Today's Topic: Rivnuts From: Doug Knight > A Rivnut relies on friction and possibly a keyway to resist > torque, and could possibly start turning in its hole, making it > impossible to loosen or tighten the screw, especially after a lot > of use. I have used hundreds of rivnuts in sizes 1/4" thru 3/8" on thin wall steel square tube .065" and .049. To install these requires a proper torque setting. Once established these then can be set by hand (feel) with a bent flat bar with a hole proper size, fastener and wrench. Price? FREE. If you over tighten (over torque) you have to drill them out as they are not centered anymore. Requires extra drilling to install for two piece parts. Rivnuts also strip easily TOO!!! Talk about my over kill!!!! You've already painted the Golden Gate Bridge (wing pieces three plus coats) and now this. I don't think Planter Bob is that wacked any more. Or is this becomming a common Bearhawk afliction? +++ #3389 Subject: Re: [Bearhawk] Today's Topic: Rivnuts From: Bruce A. Frank I use a product called "Nutsert" which rolls a little knurled flange over to lock it in the hole. I have found them to lock more solidly than Rivnuts and they are available in galvanized or stainless steel-- much less likely to strip. The limited use tool is also relatively inexpensive and can be rejuvenated by replacing a grade 8 machine screw. I buy the Nutserts through McMaster-Carr where they are less expensive than they are through A.S. or Wicks.. The tool is available through, at least I bought mine there, Aircraft Spruce. +++ #3407 Subject: Gross Buffoonery Slows Down Progress From: Russ Erb Well, KRAP! DON'T LET THIS HAPPEN TO YOU! While you're studying your plans for various misspellings (had to check the dictionary to make sure that was right), take a look at drawing #10. Take a look at the gussets that go around the aileron hinges. Where the pushrod attaches, the gussets are .032 thick, and at the other hinge are .025 thick. Think there might be a reason for that? Note also that other than the thickness, the gussets are identical in size. Now, just imagine that you cut out these gussets between 6 months and a year before you actually install them, and store them in one pile. Can you see where a problem might creep in? If you're thinking that you might forget that there are two different thicknesses, then you're far more perceptive than me! Yes, I just grabbed the next one in the pile and slapped it on in each location. Thus, several of them are in the wrong location. I found this while researching the thickness for the Rivnuts. I asked Bob through Mike, and he sent me to the detention hall of rivet drilling. I get to drill out the wrongly placed gussets and make new ones (because the holes won't match). Something else for you guys to watch out for... +++ #3621 From: Russ Erb Subject: [Bearhawk] Lotsa Questions > 3. On plan 11, on the bellcrank drawing, please explain the > construction of the hinge and spacertube assembly. I just can't seem > to picture it in my mind. What is "AFTER WELD, INSTALL BERG. MRC R- > 4FF referencing? I just shot a couple of pictures for the CD that will make this very apparent. Until then, let's try to use words to explain. "BERG. MRC R-4FF" is Bearings MRC R-4FF. Study the cross section of the hub of the aileron. You will see that there is a shelf at the top and bottom of the tube that the outer race of the bearing rests on. In between the bearings, there is a short piece of tube over the bolt which is the precise length between the bearing hubs. This tube takes the compression force when the bolt is tightened, so that the bearings do not carry any side loads. Be precise in making this part so that there is no side load on the bearings but no slop between the bearing and the bellcrank. A few thousandths is the difference between slop and too short. If you screw it up, do it again. The flight control system deserves the highest quality you can give it. Not shown on the drawings but shown in my pictures are AN970 washers (fender washers) on either side of the bellcrank, which are spaced away from the bearings by AN960L washers (to prevent rubbing on the bellcrank). These washers contain the bellcrank in the unlikely event that bearings fall apart, so that the bellcrank does not fall off. You will be able to fight your way back to a landing instead of losing control. +++ #3872 From: Dan Montee Subject: More hole questions I built my support frame jig per the condensed 1995 BT's I got with my plans. That was over the summer. Just got to building my wing parts and realized that the BT drawing calls for 3/16 holes on 4" centers, that's what I built, and drawing #11 calls for one 3/16 and one 1/4". Did I miss an engineering change somewhere or is there something (another thing?) I don't understand? +++ #3873 From: Doug Knight Subject: Re: More hole questions 1/4" is the correct size, should not be a problem to drill it out. Dwgs. #4 & #13 also supports this. Built my jig last week and should finish mine up tomarrow. Only had to rebuild one aileron support frame after I found it out of tolerance. Because I had drilled my ends like Bill Johnson's, I only needed to use a Unibit to remove the offending tube stubs to save the support ends. +++ 3874 From: Kevin Deutscher Subject: Re: Re: More hole questions? look again? You might want to slowly revisit the hole sizes at Station "D"and 'E". Some are .250 some are .188, or did I miss something? +++ #3876 From: Russ Erb Subject: Re: Re: More hole questions? look again? > Some are .250 some are .188, or did I miss something? Yes--study the flap and aileron hinge mount drawings. Some attachments use AN4 bolts and some use AN3 bolts. +++ #4048 From: "William & Delinda Johnson" Subject: 023 Update - Wing Hardware Jig I am in the process of finishing my wing hardware (flap and aileron mounts) - thus I built the jig on page 6 of the Summer 1995 edition of Beartracks. Based on a comment made in the July 1999 Beartracks (only tack weld), I was curious about why everything is so accurate but the flap hinges MIGHT not fit correctly. Well, I gave it no further thought until I verified (as I always do), the jig with the plans. Yes, I should have done this first . . . Now, I may be wrong and the jig is correct. I recognize that many, many builders have made their parts. So, I may be wrong, please let me know. Get out page 13 of the plans. Look at the Flap hinge mount in the lower middle of the page. Notice the 1/16 inch difference in the mounting hole and the center point of the hinge. The center point is 1/16 inch BELOW the mounting hole. Now look at Summer 1995 edition of Beartracks, page 6, top jig. The tab that supports the center point of the hinge (middle tab on the 8 inch square tube). The 1/16 inch difference is ABOVE the mounting hole. Net effect - your flap hinge is 1/4 inch higher than the plans indicate. Could that be the reason for the comment in the July 1999 Beartracks as that is a BIG difference and would be obvious when assembled. I can envision those of you who have already made your parts scrambling for the plans. Either I have ruined your Christmas or just gave you a scare. Let me know which is correct! Of course, you are within your rights to demand a recount!!! +++ #4049 From: Doug metalfab@p... Subject: Re: 023 Update - Wing Hardware Jig Dwg #13 is correct, my BT '95 appeares to show evidence of correction/ tampering at some point. If your piviot hole is 1/16" above the bolt center line then your net error would be only 1/8" not the 1/4" you stated. If you look at Dwg's #9 & #10 and look at where the chord line is in relationship to each pivots of both the flap and the aileron it becomes obivious. When I saw the hanging Chad in the BT '95 for the jig several mounths ago, I back tracked and did all the math to make sure all was right. And it was. No recount required. +++ #4050 From: "William & Delinda Johnson" Subject: RE: [Bearhawk] Re: 023 Update - Wing Hardware Jig Yes, I agree the number is 1/8th not 1/4 as stated. However, if Dwg 13 is correct and all the other plan pages are consistent, then your saying the jig as drawn in BT needs to be changed to 1/16th below the line as the remedy??? +++ #4051 From: Doug metalfab@p... Subject: Re: 023 Update - Wing Hardware Jig My dimpled jig Dwg reads Yes! 1/16" below. I wonder when the correction took place? You are clearly 410 plans set ahead of me. +++ #4052 From: "Dan Montee" Subject: Re: [Bearhawk] 023 Update - Wing Hardware Jig I am also building the wing hardware and had the same curiosity. I assumed it had something to do with the difficulty of aligning the three hinges. I don't have the original 1995 BT but the condensed 1995 version, pg 10, I received with my plans is correct. I still have the question of why tack weld only? +++ #4053 From: "William & Delinda Johnson" Subject: RE: [Bearhawk] 023 Update - Wing Hardware Jig I just spoke to Bob. He said there was a correction for the Jig in a later edition of BT - I must have missed it. At any rate, just put the hole 1/16 below the line on the jig - not above. About the tack weld, I asked why since the aileron hinge is not tacked welded and thus can't be changed. He said that on his last set of wings, his spars must have been slightly tilted which caused the flap/aileron to be low. He put a washer under the aileron hinge but made new flap hinges. So, if everything is made VERY accurately, no need to tack. If your spar is not perfectly perpendicular, then some correction may be necessary. Mystery solved - recount avoided. +++ #4054 From: Russ Erb Subject: [Bearhawk] 023 Update - Wing Hardware Jig Ah, the hazards of being the early adopter... I was gone for the weekend, so I'm late into the fray. Bill--look at the drawing for the Summer 1995 Beartracks on your BHCD (V1 or 2). Though not obvious, you can see Bob's hand drawn correction on my copy, so at least it was caught by #164. I actually drew out the hole hinge assembly and found one or two other minor dimensional errors, but not more than 1/16" or so. As Planter Bob would say, too damn picky. I welded up my flap hinge mounts long before the "tack weld" bulletin. The first wing went together fine. We'll see how the second goes. I pulled the rear spar about 1/8" out of straight behind the fuel tank bay through gross buffoonery. I had tie-down straps ratcheted down hard to hold the nose skin in place while drilling. Nothing wrong there. Screwed up by not releasing them before drilling the skin to the false spar. Not a problem anywhere else because of the center ribs. Not as stiff here. Since fixing the problem would have been several hundred hours (like new rear spar), I chose to compensate instead. +++ #4231 From: Russ Erb Subject: [Bearhawk] Aileron drive linkage > Just a short question, on dwg 11 the frame suport crossection > B-B and A-A the longer section of 7/16 x .095 go towards the > pully and the bellcrank? Yes, the long section of each one is on the side of the pulley or bellcrank. It spaces the pulley and bellcrank up from the main tube. +++ #4414 From: "Collin Campbell" Subject: aileron and flap hinges I wondered if anyone has experienced any difficulty in bolting the aileron and flap hinges to their respective parts. The flange that the bolts go through are quite narrow (9/16"). This leaves very little room for the 3/16 bolt when you consider proper edge distance and allowing for the radius of the bend in the fitting. My fittings came out perfect just like the plans show, but the bolt head rides up just a little on the radius of the bend. I thought a washer with a little relief filed off one side might solve the problem, but then I noticed that there wasn't enough clearance to the side of the bolt to get a socket wrench on it to tighten. As you remember there is no access to the other side, the bolts just screw into nut plates so they can be removed if needed later, not to mention how much easier it is to cover the flaps and ailerons without the hinges in the way! I was wondering if anyone would see a problem with using allen headed cap screws in this situation. The heads are somewhat smaller and installation would seem much easier. Any thought? +++ #4415 From: Russ Erb Subject: [Bearhawk] aileron and flap hinges > I thought a washer with a little relief filed off one side > might solve the problem, but then I noticed that there wasn't > enough clearance to the side of the bolt to get a socket > wrench on it to tighten. This probably won't help you, but I drilled the hinge mounts first (for welding in the jig) and drilled the spars on assembly. As you might expect, the hole in the spar is not exactly where the plans show it to be. I had pressed those pieces, so the part that goes against the spar has a small curvature. I chose not to worry about it and it hasn't seemed to cause a problem. +++ #4416 From: Del Rawlins "Float-By Shooter" Subject: Re: [Bearhawk] aileron and flap hinges Is there room between the hinges and nose ribs to get a crows foot wrench on an extension on the bolt heads? Otherwise you might bend/grind an old wrench as required. The allen head bolts would probably be the easiest way to go. +++ #4421 From: "David McCarroll" Subject: Re: [Bearhawk] aileron and flap hinges Another solution is to use 12 point bolts with a shoulder. The -3 bolts that you are speaking of would use a 1/4 or 5/16 12 point socket and the shoulder would be roughly the same diameter as the socket. They are a little more expensive than traditional bolts, but are easier to use in the application you are speaking of. +++ #4429 From: "Mike Eldredge" Subject: Re: aileron and flap hinges I had the same concern, so I made the flanges slightly wider, and moved the bolt holes out a smidge, enough to get a socket over them. My concern is that they won't fit between the nose ribs. Can anybody tell me what the distance between the nose ribs is? +++ #4981 From: "William & Delinda Johnson" Subject: 023 Update In the spirit of getting the group focused back on building Bearhawks, I took the opportunity of my illness to update the web page. Seems to be a virus going around - my kids got it, my wife got it, but I vowed to be tough. Well, perhaps I was overly macho! Anyway, not to digress and start a discussion on illness, here are some pics on building aileron and flap hinge mounts and a short overview on the strut link. 1. It took me 5 tries to get 2 linkages that meet my standards of building. Since the linage fits inside the strut fittings, the bolt holes need to be very precise and perfectly straight! Build a drill guide to ensure you get the holes matched on both parts. Also, the interior welding on the linkage is challenging. http://home.fuse.net/wjohnson/wcstrut11.jpg 2. Hinge mount jig - sorry for dark blurry pictures - no charge! http://home.fuse.net/wjohnson/wchmtool1.jpg 2. I made my hinge mounts differently than Bob's newsletter. My view is that it would be easier to add washers to change the angle of the hinges than to drill holes for the rod ends after welding. Using a divider head and bridgeport mill, I predrilled ALL the rod end holes. Also, notice the holes in the 'U' channels for backside welding. http://home.fuse.net/wjohnson/wchm7.jpg http://home.fuse.net/wjohnson/wchm4.jpg http://home.fuse.net/wjohnson/wchm5.jpg http://home.fuse.net/wjohnson/wchm9.jpg http://home.fuse.net/wjohnson/wchm10.jpg http://home.fuse.net/wjohnson/wchm11.jpg http://home.fuse.net/wjohnson/wchm12.jpg http://home.fuse.net/wjohnson/wchm13.jpg http://home.fuse.net/wjohnson/wchm14.jpg http://home.fuse.net/wjohnson/wchm16.jpg http://home.fuse.net/wjohnson/wchm18.jpg http://home.fuse.net/wjohnson/wchm21.jpg So that's it for now. I am making the remainder of the 4130 parts and hope to begin wing assembly soon. As a side note, the Culver is coming along as well. I have purchased new engine parts for the rebuild and will soon be making the wood tail section. +++ #4985 From: "William & Delinda Johnson" Subject: RE: [Bearhawk] 023 Update > Is there a reason not to machine these from a piece of bar > stock? I can't really think of one aside from the few ounces > of weight. No, I would make as shown. Just follow the instructions on the Bearhawk CD. You need to account for shrinkage and a drill guide is essential. Also, one of the inside welds is completed BEFORE joining the two halves. When you get to the interior weld on the other half, start on the back. Bounce the flame off the tube and get things really hot! Also, I intentially made my the linkage with thicker walled tubing to account for any offset in the final drilling procedure. I have two extras, that frankly, are ok to be used. I am just a perfectionist and had to get the holes within .0005 inches. Kinda crazy I know. They are yours if you want them. Let me know . . . +++ #4986 From: Rod Smith rsmith@a... Subject: Strut Links > 1. It took me 5 tries to get 2 linkages that meet my > standards of building. Bill you have managed to make me feel better about my lack of welding skill. I have made three attempts at these, all discards. On the third try I had a friend at work whom is the best Tig welder I know give it a try. He did a beautiful job but could not get to about 1/4 of the circumference of the inside weld. I tried to finish it with the torch and ended up with a lumpy mess that I was sure didn't have much if any penetration. He wondered why they couldn't be machined and I couldn't think of a good reason other than extra weight. I basically decided to wait until after welding the fuselage and try them again when my welding is hopefully better. +++ #4987 From: Budd Davisson Subject: Re: Bill's Strut Links I took a look at the shot of your strut links and I have only one thing to say: any of us who thought we knew how to weld are kidding ourselves. YOU are a welder: I'm not sure what the rest of us are doing. BEAUTIFUL WORK!!! You've really mastered the art form. +++ #4988 From: Budd Davisson Subject: Re: [Bearhawk] Strut Links To those of you who haven't made your strut links: DON'T I just talked to The Bob about them and we've come up with a much simpler solution that will show up as a builder option in an upcoming Beartracks. Just though ya'll like to know. +++ #5102 From: Russ Erb Subject: Control Cable/Flap Pushrod Interference This is an old problem that was brought up before, but disappeared from discussion because it was way ahead of most of us. I had intentionally left the bottom skin on my first wing unriveted in anticipation of eventually remembering whatever it was that I forgot. It wasn't that I knew I had forgotten something, but rather that history has shown that something always seems to creep up. With the skin not permanently attached, it would, in theory, be easier to fix whenever I finally thought of it. Well, thanx to Kevin Deutscher, I now know at least one thing that I forgot. In the aileron control system, there is one cable that goes from one aileron bellcrank all of the way across the fuselage to the other aileron bellcrank. At each wing root, this cable passes through a fairlead that holds it up from drooping down too far. Even so, there is 9 feet of unsupported cable hanging in the wing. In the normal configuration, the cable does no touch anything else. Of course, I'm doing this in a vertical jig, so gravity isn't working in the normal direction. Even so, when the flaps are deployed, from about 10 degrees to about 40 degrees the flap pushrod rubs on this cable. Someone brought this up a long time ago, and reportedly "The Bob" went out and inspected the prototype and found that, much to his surprise, he had the same problem. Three obvious solutions immediately present themselves: 1. Delete this e-mail quickly and pretend you never heard about this, and quietly ignore it. 2. Only position the flaps at full up or full down (not very practical). 3. Put some plastic tubing over the flap pushrod (won't work--would interfere with operation--the mechanism is already pretty close tolerance). "Okay, Mr. Smarty-Pants" (hey, that's not where my brain is!), "I bet you've got another proposed solution." Well, yea... This will probably make no sense without a picture, but that will have to wait until I've installed it. The idea is to attach a bracket to rib 6 (just outboard of the flap drive), and unto this bracket attach an Adel clamp (MS21919 clamp). Install a fairlead in this clamp. This fairlead will pull the cable up about 3/8" so that it will clear the flap pushrod in any position. The angle of turn through the fairlead will be far less than one degree, so the added friction will be minimal. This will also require slightly enlarging the oval holes on a few selected ribs, but I've already done that to clear other things in other places. That concludes today's building tip. Tune in again soon when we will discuss balancing the aileron. +++ #5103 From: "Collin Campbell" Subject: Re Flap cable interference > Three obvious solutions immediately present themselves: > > 1. ... 4. Wrap the cable itself in the area of the rub with an anti-chafing material. 5. The mechanism is very close tolerance on the sides, but there is room for a thin strip of anti-chafing material on TOP of the flap push rod. (Probably best solution for those who may have already skinned their wings) 6. Don't worry about the rubbing problem, as Bob apparently hasn't. How many hours does the prototype have by now? The rubbing would only occur during brief portions of flight and the rub is very light. Apparently Bob doesn't consider this serious as he also wraps the trim cables around each other to provide friction in the system. +++ #5105 From: Doug Knight Subject: Re: [Bearhawk] Ailreon Cable/Flap Pushrod....Here's the FIX Ok, I played around with for about an hour and this is what I have come up with. The rate change in the cable in roughly 108" is just around 2.2" . Clearance at the of the Aileron cable to push rod at zero flaps appears to be roughly 3/8". Given these parameters I have come up with this fix and anyone with a completed wing could retro the fix. Bend the flap tube at about one diameter off set at about 3 3/8" from the center of the forward T. Pin to pin length should be maintained. This may be a new part on retros. Next the rear #2 support frame end will have to hogged out lower approximately 3/8" to allow some clearance to accommodate the new bend. Approved or not this is what I am going to do. Should I make a drawing? +++ #5107 From: Russ Erb Subject: Re: [Bearhawk] Ailreon Cable/Flap Pushrod....Here's the FIX I briefly considered that, but I don't like the idea of a bent pushrod under compression. Just seems too likely to buckle. +++ #5109 From: Doug Knight Subject: Re: [Bearhawk] Ailreon Cable/Flap Pushrod....Here's the FIX More design propagation. I had totaly neglected the center flap hinge mount and all that is allowed to be removed there is about 1/4". I understand what you mean buy a "bent pushrod under compression", maybe a destructiove test is needed here. What would be the safe working limits? And what would be the failure limit? The rod in question is slightly over ~6" @.049. Bending and increasing to .065 or .083 might be and end solution and be within a safe compression loads. Still, I think I can make this all work if given a failure load limit for testing. So the real question is how stong of a bent pushrod is needed to open the "barn door size flap?" Ok, here is a dumb answer. What holds the T at the pushrod is a little AN3 bolt in sheer. +++ #5110 From: "Bruce A. Frank" Subject: Re: [Bearhawk] Re:cable rubbing On my Colt (PA-22) fuselage, elevator cables, though routed through pulleys, constantly rub against a phenolic block fastened to a bottom tube in the fuselage. This is an OEM design and the elevator cables certainly receive much more movement that the flap cable. When I disassembled the plane, the cables were original from '63, but were only lightly polished where they contacted the block. +++ #5111 From: Budd Davisson Subject: Re: [Bearhawk] Re:cable rubbing Oh, the aileron cable. Wear issue is bigger. I take back what I said, but at least one airplane I've owned, and I can't remember which one (I think the Mustang), had pieces of micarta riveted in several places in the wings for the same reason. Still, it's better to use some sort of fairlead to show the cable where its' supposed to go. +++ #5112 From: Doug Knight Subject: Aileron cable/Flap tube problem and solution? For those of you who need the graphic picture, the page is 360K. http://www.geocities.com/doug_knight_94501/Bearhawk_tools/pic6.html I'm willing to bet an andrew jackson, any takers. +++ #5263 From: Russ and Penny Erb Subject: Erbman Pix Posted of Aileron Cable Mod Back to something you might care about... In the recent past, I mentioned that I was making a modification to address the aileron cable rubbing on the flap pushrod. I added a fairlead on the rib just outboard of the flap pushrod. The cable moved all of about 1/4", but it made a big difference. The result is also very elegant and simple, in keeping with the Bearhawk philosophy. I'm sure "The Bob" would approve. Even "Planter Bob" would approve. Go to http://www.eaa1000.av.org/pix/erbpix/erbpix.htm and page down to the "Bearhawk Reference CD Addendum" section to see pictures of the installation. I will use this section for important updates in between major CD revisions. +++ #5293 From: Mike Eldredge meldredge@a... Subject: support tube end - welding idea (sent a .gif of this, but not sure it went through) I had an idea with the flap and aileron support tube ends. Instead of welding on the inside of the u-shaped tube end, why not cut a slot and weld from the outside? It seems like this would be a much easier weld. Would it be of equal/sufficient strength? ___ | \ | | \ | | \ |- - --------------------------------- | \ | ===== | / |- - /-------------------------------- | / |__/ (you'd cut a slot where the '=======' is in the .063 'U' channel, then weld it to the tube) What do you guys think? +++ #5301 From: Russ and Penny Erb Subject: RE: [Bearhawk] support tube end - welding idea Look at the CD for how Bill Johnson did it (hole in the end). I would recommend this, since Bill is much smarter than me on this--I fought with the corner reflector aspect of this weld and got a serviceable but not pretty weld. Somehow managed not to burn myself too bad... +++ #5306 From: "William & Delinda Johnson" Subject: RE: [Bearhawk] support tube end - welding idea Mike, I would at least partially weld on the inside of the U shape tube end - top and bottom, right and left, 3/4 of the depth of the channel. Use the hole method to finish the end unless your looking for a real challenge. As Russ points out, the flames will bounce back and make the process very difficult if you attempt to go beyond the 3/4 depth. The weld was beyond my skill level (and I did not think I could ever make that weld look good regardless of the amount of practice) hence I developed the Johnson method. Make one extra U channel. Take the one worst one and use it for welding practice and to get the right torch tip. AW204 if you use the smith torch. +++ #5332 From: Mike Eldredge meldredge@a... Subject: Re: support tube end - welding idea Thanks for the replies on this one. I was already planning to cut a hole in the end to weld the end of the tube to the bottom of the U from the outside, like you did. I was just wondering if cutting a slot down each side of the U, and then welding the U to the tube from the outside through/along the slots could be done instead of welding the inside of the u-channel to the tube, top & bottom, right & left. If the resulting assembly were strong enough, I imagine that would be quite a bit easier than welding the inside of the U to the tube. +++ #5333 From: "William & Delinda Johnson" Subject: RE: [Bearhawk] Re: support tube end - welding idea Mike, I would recommend you weld on the inside. That way you have support on both the top and bottom of the tube. 4 locations instead of essentially two . . . +++ #5403 From: "Dan Montee" Subject: Aileron pulley bracket forming tip I just finished my aileron pulley brackets. In addition to my usual misadventures with set back and bend allowance, I had considerable problems bending these little odd shaped brackets. .100" 4130 and the odd shape did not lend themselves well to the dead blow hammer and form block method. I prefer to use my Low Buck plate brake but it wouldn't allow for all the bends. I finally took the brake apart and cut the inside of the 1/4" fixed base plate back 3/8" and about 1 1/2" wide. This allowed me to start on one end and work all the bends into the part. After 3 hours of misadventure I can now layout, cut, and form the part per drawing in 20 minutes. I added copious notes to my log after reading the experiences of Erbman and others who have gone before me regarding "adjustments" to these brackets on assembly. I have a feeling I may be making these brackets again. It ain't the building time that prolongs airplane building, it's the learning curve! +++ #5458 From: "William & Delinda Johnson" Subject: 023 Update New pictures of wing aileron and flap control assemblies: 1. The Support Tube at the wing root requires threaded end caps. The threading was done AFTER the welding. http://home.fuse.net/wjohnson/wcst1.jpg http://home.fuse.net/wjohnson/wcst2.jpg 2. The support tube fairlead guide being fitted. http://home.fuse.net/wjohnson/wcst3.jpg 3. The Support tube flap lever guides will not be welded in place until final fit in the plane. See construction pics. http://home.fuse.net/wjohnson/wcst4.jpg http://home.fuse.net/wjohnson/wcst7.jpg 4. The flap lever itself - finished and ready for assembly. http://home.fuse.net/wjohnson/wcfl1.jpg 5. The aileron cable pulley brackets were bent over a form block. I started in the middle and worked out - took only a few minutes. http://home.fuse.net/wjohnson/wcacp1.jpg http://home.fuse.net/wjohnson/wcacp2.jpg 6. The completed flap arms. I did not have 7/8 x .058 so I had to turn out a thicker tube to 3/4 internal diameter. Also, notice I did not weld the inner spring retention washer - it just floats. If you try to weld expect a big mess! http://home.fuse.net/wjohnson/wcfa3.jpg http://home.fuse.net/wjohnson/wcfa1.jpg http://home.fuse.net/wjohnson/wcfa2.jpg 7. Flap arm pushrods and bushings. http://home.fuse.net/wjohnson/wcpr1.jpg That's all for now. Wing metal parts are not complete except for painting and final fit. Getting real close to needed that wing jig! +++ #5717 From: "Tim Anderson" Subject: Aileron bellcrank I saved a past post referencing the explanation of the bearing in the aileron bellcrank..I can picture it (even without Russ's CD V2). But, the plans list 3/4 X 0.083 tube for the bellcrank pivot. I can't find 083 tube anywhere. From the plans, sec C-C lists 0.625 as the inside dia. This would correspond to about 065 wall tube. Anyway, it's either 065 or go up to 095 and ream the heck out of it. Any suggestions. Any sources for the R-4FF bearing? Tim #398 +++ #5718 From: n95mf@a... Subject: Re: Aileron bellcrank fuzzet@h... writes: > > Any sources for the R-4FF bearing? Wicks Aircraft +++ #5719 From: Steve Eldredge Subject: RE: [Bearhawk] Aileron bellcrank I bought mine from motion industries. It took a lot of digin, and I thought I was purchasing them local. I saved $.50 a piece from the wicks price, then discovered I had to wait for shipping. Go Wicks, Steve Eldredge +++ #5720 From: Doug Knight Subject: Re: [Bearhawk] Aileron bellcrank R-4's can be bought from McMaster/Carr for $4.09 ea, the (FF) means double sealed, these same bearings are used in older copy machines. All the differance that I see in the price is that you are blessing someone wallet. Rated at 52,300rpm and we will use them at a much less rated speed say like 10-15rpm. use the .095 wall for the carrier and machine it down Doug Knight #433 +++ #5721 From: "Dave Visser" Subject: RE: Aileron bellcrank If you are looking for 3/4" X .083 tube, Shapiro supply of St. Louis MO carries it. Check out www.shapirosupply.com Dave Visser +++ #5723 From: "Todd Chisum" Subject: Re: Aileron bellcrank > Any sources for the R-4FF bearing? I'm pretty sure that is the size of bearing I used to order regularly from a local bearing supply house. Check the yellow pages, that is a common size and should be not too expensive. Todd Chisum +++ #5724 From: Russ and Penny Erb Subject: RE: Aileron bellcrank I checked my drawing and found a note to use 3/4x.095 because 3/4x.083 was not available. Look carefully at the drawing and see that you have to turn a shelf into the tube to hold the bearing. The dimension of this turned area is 0.065, but the middle portion of the tube is thicker. This shelf is required so that the bellcrank doesn't slip off of the bearings. I got my bearings at a local storefront for Motion Industries. Russ Erb +++ #5725 From: "Float-By Shooter" Subject: RE: Aileron bellcrank > I checked my drawing and found a note to use 3/4x.095... Is there any good reason why a lathe-less builder couldn't use a piece of 3/4x.065 tube, slip a piece of 5/8 tube of appropriate length inside, and spot weld the two together? Del Rawlins +++ #5728 From: Russ and Penny Erb Subject: RE: Aileron bellcrank A very interesting idea--when you say "spot-weld" I assume you mean do rosette welds. If you can get sufficient strength in the rosette welds and not have them get in the way of the bellcrank arms it should work. Make sure the inner tube is not so thick that it rides on any part of the bearing other than the outer race or it will cause additional friction. Give the welds a good test, since the control system is not the place to be having weak parts. Russ Erb +++ #5729 From: "Float-By Shooter" Subject: RE: Aileron bellcrank > A very interesting idea--when you say "spot-weld" I assume you > mean do rosette welds... Actually I meant spot weld (like is used for autobody work) but yeah, rosettes would probably be better. With the rosettes concealed *under* the bellcrank arms, it would look just like the standard item. 8^) I suppose I could take a 5/8" drift and try to hammer the inner tube out of a test piece but I don't know what that would prove. The part isn't going to fail in that direction, and even if it did a fender washer on the bellcrank bolt is cheap insurance. My only real concern would be reduced stiffness at the joints between the bellcrank arms and the thinner outer tube, but my recollection of this part (plans are at the shop) is that there is triangulation via a brace tube between the bellcrank arms, so I don't think my modification would have any effect, other than being easier to construct. The only reason that I can see for the thicker tube is to provide the "step" to keep the bearings in their proper place, but then again I am not a trained engineer so I could be wrong. But I think that for now I'm going to plan on making my bellcranks this way. Del Rawlins +++ #5730 From: "Tim Anderson" Subject: RE: Aileron bellcrank I sent Bob a "letter for the newsletter mailbag" concerning the bellcrank/bearing construction. From the plans, it was not overly obvious to my pea brain, at least not at first. Hopefully, he will detail it's construction for future builders that may not have access to electronic question answering. Oh, I did find some 083 tubing at Shapiro metals in St Louis. +++ #5736 From: pfflyerz@c... Subject: aileron stop Bob has noted in Beartracks how and where to weld control stops for the elevator and the rudder, but I don't recall ever reading about aileron stops. The control sticks can only pivot so far in either direction. Is that the defacto control stop or should there be something else that I am missing? Pat Fagan #232 Pearblossom CA +++ #5737 From: Russ and Penny Erb Subject: RE: [Bearhawk] aileron stop I agree that there are no obvious stops at the aileron. When I move my ailerons to the limits as shown on Drawing 1 (+/-20 deg) there is still a small amount of possible movement left. I've figured that the limits to the aileron movement would be in the possible movement of the stick. I'm not sure where the stick will contact the mechanism, but plan on filing it on assembly to give the proper limits. It might be a good idea to add a doubler there as well. The following is what 14 CFR 23 has to say about control stops. Note that the stop is not specifically required to be at the control surface: Sec. 23.675 Stops. (a) Each control system must have stops that positively limit the range of motion of each movable aerodynamic surface controlled by the system. (b) Each stop must be located so that wear, slackness, or takeup adjustments will not adversely affect the control characteristics of the airplane because of a change in the range of surface travel. (c) Each stop must be able to withstand any loads corresponding to the design conditions for the control system. [Amdt. 23-17, 41 FR 55464, Dec. 20, 1976] (Note: in government parlance, "FAR" now refers to "Federal Acquisition Regulations". The Federal Aviation Regulations are properly referred to as Title 14 Code of Federal Regulations (14 CFR)) Russ Erb +++ #5742 From: Doug Knight Subject: Re: Re: Aileron bellcrank zipppydoggg@y... wrote: > > Do you have the McMaster Carr part number for these bearings > handy? I don't have the plans in front of me, how many do we > need? Part# 60355K87, I didn't know this would such a fuss and would have included it the first. Need (4). Doug #433 +++ #5743 From: "Michael Geurink" Subject: Re: aileron stop I think an inspector or anyone else with nix authority, if they felt like it and they had a hangnail on their left pinky that day, could possibly interpret (b) to mean you couldn't use a stick based stop system, with cables anyway; probably couldn't say anything about tubes. Maybe I'm wrong. Mike in the Amazon +++ #5744 From: Russ and Penny Erb Subject: RE: Re: aileron stop Except that experimental amateur built aircraft do not have to meet 14 CFR Part 23. I only quote it here because usually it is a good guide of what we ought to do. Russ Erb +++ #5765 From: Fred Spain Subject: rod ends I just "won" a bid on ebay for 10 rod ends for $52.01. Now they have relisted more which you can buy outright before the bidding starts for $39.95. They look good to me. Check 'em out on ebay #582714293. If they are OK, I am a winner even at $52.01 Fred Spain +++ #5777 From: pfflyerz@c... Subject: some control system observations I now have all my control surfaces hooked up and operable (except for the trim tabs) and can now hanger fly to my hearts content. I have made some observations over the last few weeks that I thought I would pass on. 1) I poured the balance weights for the elevators directly on the elevators. That went so well that I decided to try and pour the aileron balance tubes as well. I had originally filled them with lead shot and plugged the ends with aluminum plugs, but they were a little light. I thought if I could fill the area taken up with the aluminum plugs I would get the needed extra weight, but I couldn't fill the tube with molten lead as it solidified too quickly. The solution: Fill the tube with shot then pour a molten plug in the last couple of inchs. Turn the tube around, pour off some shot and pour a plug on that end. Or: Instead of aluminum, use 3/4 x .035 4130 for the tube and fill with lead shot and plug. 2) The bottoms of the control sticks come so close to the horizontal support tube at full deflection that it might be what Bob uses for a control stop. For more precision, I added a bracket to the bottom of the sticks. A set screw attaches to the bracket and bumps against the stick tower flange to allow for adjustment and a positive stop. 3) For the flap retract springs, Bob says buy screen door springs. I bought four, but you only need two. I kept cutting them down and trying them out. They are now only about six inches long relaxed and they are getting pretty hazardous to stretch via my access holes. I finally began stretching them through the fuel bay lightening holes. Finally got them short enough to hold the flaps up, until I hooked up the cables. I cut them back some more, but they wouldn't always retract fully. I added a bracket to the top longeron and attached a helper spring directly to the flap control arms which seems to do the trick. I guess that was all. Pat Fagan #232 Pearblossom CA +++ #6301 From: Russ and Penny Erb Subject: RE: Rod Ens From: mdk@t... [SMTP:mdk@t...] > > Could anyone on the board give me either the Aircraft Spruce part > number or the Wicks part number for the rod ends. MS 21152-2 Spruce REP4H6 $49.95 Page 140 2000-2001 Catalog Can't find it in Wicks catalog. Russ Erb #164, Edwards CA +++ #6367 From: "Tim Anderson" Subject: aileron/flap hinges I don't know if these subject has been covered in the distant past, so I'll throw in my observations of the hinges from heck. AS a neophyte welder, they are a bit intimidating at first. OK, the hinges (rod mounts, spar side) are complete. About 50 hours of work and a couple dollars of materiel per hinge (rod ends not included). BUT IT WAS A LEARNING EXPERIENCE, therefore I met the FAA's definition as a true homebuild project, rather than a read the construction manual, find the correct part and bolt it in place (2 minutes of work). I started with milling out the tubes for the rod ends... time consuming, but an education on using my Harbor Freight special milling/lathe mechine. Don't know how one would do this without a lathe, I guess if one had the right reamers. I cut and filed the flap hinge material and drilled a starting hole for the welding on the back side (simular to Mr. Johnson's work, he is a "Mr." in my book due to his masterful welding). I thought I was getting smart by cutting the push rod hole BEFORE bending the flange over...wrong....it curled. re-made those plates with out cutting the rectangular hole. I tacked the flap mounts as per Bob recommendations. My "plug" used with the jig got stuck....seems that when I tacked the tube and plate, enough scale/tube distortion occured inside to freeze up the plug. I shortened the plug just a tad to avoid the tack area. the critical measurement is the pivot-to-hinge tube end anyway. The aileon hinges were a bit of a challenge, but I persevered. My recommendation is to cut the bolt stubs LONGER than the plans calls and trim/file them back upon completion. Welding in the tiny crouch caused burnback on the bolt tube for this new-be welding. My "bent" tubes could have been "bent" more than they were. On to the next part. Tim #398 +++ #7492 Date: Thu, 30 Aug 2001 12:57:10 -0000 From: t18cox@ Subject: Dillsburg, wings I used Bob's method of Loctite 609 for aligning and securing the rodends in the flap and aileron mounts. It really works well. With the first wing I was a little sloppy with the Loctite and found it will strip Stits Epoxy if runs are not promply wiped up. I was careful to lightly coat the rodends and insert them on the second wing and had no problems. Bill Cox #303 >>> 2mar02 #7686-9153 +++ #7989 From: Budd Davisson Subject: Re: Digest Number 587 It needs a few minor tweaks that I'm aware of. I'd like to know from those flying how the new rudder aerodynamic balance effects the rudder break-out forces, for instance. The original balance area was too big and the rudder a little light. All of the plans show a slightly smaller one and I'd like to know if the change had much effect. There are some minor tweaks needed in the aileron cable/flap interference we've all talked about. And there's the need to reflex the flaps. The 540 in Bob's airplane runs hot with when worked even slightly hard so there are some cooling issues with the big motors. Cowl flaps may be in the offing. The nice part about this airplane, however, is that the basic design is so good that improvements just make a good thing better, rather than trying to compensate for something that is basically wrong. bd >>> 4sep02 #9154-11297 +++ #9450 From: Benton Holzwarth Subject: Rod Ends I've been working through a list of materials and tools I'll need to finish the wings. For the first time counted the number of rod-end bearings and checked the prices on 'em. Was startled to find they're as much as $25 to $50 each. (How can the airframe go together for $7k when there's over $500 in rod-ends alone?) A friend suggested I check into Van's site, where they're happy to sell to anyone, not just RV builders. I spotted in their list: BEARING M3414M 3/16X1/4 MALE RD END $8.44 I'm guessing this is the same unit as ACS carries for $23. I'm not completely sure about the extra 'M' suffix over what Bob called out for the aileron push-rod, but suspect this is what we need. I haven't spotted the others yet in the list yet, but I'd particularly like to find a cheaper source for the ten hinge rod-ends. Also, by the way, Wicks carries the R4FF (?) bearings used in the aileron bellcrank. I know the bearing supplier has been listed as a source, and might be cheaper (Wicks gets $9.70 ea in my catalog) but there is some convenience if you're already putting together an order with Wicks. +++ #9454 From: John Dougherty Subject: Re: Rod Ends > I've been working through a list of materials and tools I'll need to > finish the wings. For the first time counted the number of rod-end > bearings I got mine from Russel AT2 Surplus. 10 - RE4H6 rod end bearings at $12 each plus $5 for shipping. He like to use a fax for orders (813-775-6727) but his address is :R.Kapes, 1127 Ridgewood Dr., Highland Park, IL 60035. He may still have some so you could ask. +++ #9455 From: Russ and Penny Erb Subject: RE: Rod Ends Ah, the rod end question again. One of our perennial favorites in the early days of the list. You'll be (un)happy to know that we never did solve that issue to anyone's satisfaction. The 10 rod ends for the aileron and flap hinges are rather large and can be subjected to large loads, so you want high quality rod ends. Note that the shanks are unthreaded. I seem to remember the admonition through Mike from The Bob that threaded shank rod ends were NOT a suitable substitute, I think because of the side loads. The rod end discussions are on the Bearhawk CD under "Ailerons and Flaps". You can try some of these suppliers you see at Sun N' Fun or AirVenture. I bought a set that was personally pointed out for me by The Bob at a reduced price. Figured I couldn't go wrong with that. Well, not quite. They were actually similar rod ends but not an exact match. The shanks were slightly smaller, possibly a metric size. This required modification of the mounts and made the hinges slightly wider, such that the clearances for inserting the hinge bolt is now zero or slightly negative. I made it through, but if I was doing it again, I'd just pay the big bucks (~$500) and get the correct part number. +++ #9461 From: Tim Subject: Re: Rod Ends.....S&F Looking at the RV rudder mount rod ends, shows the shoulder of the Rodend with more material/beefier.....I own some which are threaded and don't have this feature... Any of you guy's with a Lab top at Sun&Fun?...How about an update in the next few days!!! +++ #9568 From: "Chris Vuxton" Subject: Cleaning Surplus Rod Ends I am now the proud owner of a number of those surplus rod ends. Any of you who have bought them will know that they are painted green (generally chipping off) and have some kind of gunk on the bearing itself. The question is, can they be cleaned? Strip the paint? Brush off the gunk? Shoot some white litium grease into the bearing? +++ #9577 From: "gjvf" "Jim Van Fossen" Subject: Re: Cleaning Surplus Rod Ends I also own some of the flaking, grean painted rod ends and I have the same concern about cleaning and regreasing them. I have a 2000-2001 Spruce catalog and on page 142 there are some items called ACS Bearing Regreasers. After looking at the dimensions, it doesn't looks like any of these are the correct size for our bearings although the Number 3 might work. It would be worth the $8.20 to find out. Anyway it doesn't look too difficult to make something similar that would work. I've got a long way to go before I worry about that. Let us know if you find a solution. +++ #10252 From: "Chris Vuxton" Subject: Regreasing Rod End Bearings I got some of those surplus rod end bearings and thought about cleaning them up. I used biodgradable paint stripper to get the paint off. Then I ordered the smallest rod end regreaser from Aircraft Spruce. Well worth the $8.25 plus shipping. I used "Corrosion Block" grease and it work fine, a little messy but fine. The ends are now all regreased and loose. I have a regreaser for rent. $5.00 check made out to the "Make a wish Foundation." +++ #10584 From: Russ and Penny Erb Subject: Today's Labor Saving Tip This is based on the theory that after you weld a piece you can't tell exactly what it looked like originally (unless maybe if you are Bill Johnson)... Many areas on the Bearhawk, such as the ends of control horns, have small doublers welded on, such as where control cables attach. These doublers are drawn as circular, much like washers. The problem is that circular shapes are hard to fabricate, especially on parts that small. Not impossible, but harder than necessary. Here's a method that I've used that works well: 1. Make the primary part. Drill the hole based on the pattern. 2. Cut the doubler in the shape of a square with sides the same length as the diameter shown on the plans. 3. Cut off two corners from the doubler so that half of the doubler looks like half an octagon. If you're Planter Bob, make it look like half a stop sign. 4. Place the doubler on the primary part with the octagon part away from the edge and tack weld in place. 5. Use your sander or grinder to shape the of the doubler to match the edge contour of the primary part. 6. Finish welding the doubler. 7. Drill the hole through the doubler. Trust me, when you're done, no one will be able to tell that the doubler didn't start out as a perfect circle. +++ #10585 From: "Bruce A. Frank" Subject: Re: Today's Labor Saving Tip Even a square tends to look like a round once the full circumference is welded....close enough. +++ #10591 From: "Corky Scott" charles.k.scott@d... Subject: Re: Digest Number 838 > Well, since that told me nothing, I thought I'd ask you folks--what > tension do you tighten your control cables to? I ended up feeling the same way when it came time to tighten up the drag/anti-drag rods for the Christavia wing. Eventually it came down to tight enough to do the job. I can't speak from great experience but the idea is to tighten things up enough so that deflection of the control stick or rudder pedal makes the control surface move without any slop in the control stick. It does NOT have to be taught as a drum, this is a bad thing, it puts too much tension on the pulleys and would cause early failure or wear in them. The cables really need only be tight enough to operate the control surfaces without slop in the controls. Seeing them (the cables) droop a bit in a long run isn't necessarily a bad thing as long as the controls operate without slop and there is no obstruction in the movement. Every pulley needs to have a shield over the cable to make sure the cable cannot ever pop off the pulley, but I'll bet you knew that. ;-) +++ #10712 From: Ken Beanlands Subject: Re: Control Cable material In Canada, Canadian Tire sells control cable at a very good price. If you're worried about quality, simply take a peek at the spool and you should find the same MIL spec as Aircraft Spruce. +++ #10835 From: Ken Beanlands Subject: Oversized bolts Does anyone have a source for oversized or close tolerance bolts? I have a little too much play in the wing struts that I'd like to get fixed out. I even have the NAS part numbers for the series but most of the places advertising them on the web wont talk to us little folk. Unless you're looking for a couple of hundred, forget it :-(. Unfortunately, Aircraft Spruce, Wicks and Univair do not carry them. +++ #10847 From: "bcschutt" Subject: welding and covering To all-hope you all are having a great summer day-----I have two questions 1) when welding the flap hinges, made up of a tube and small channel section---the tube gets welded at the channel approx mid point and down in the channel---how does one weld down in the channel, it seems rather tight so visability is not much and also, my tourch just goes pop and starts whistling--stop, start over???? What am I doing wrong? How much weld in the channel? just a dot at the top and bottom or must it be all the around? (2)... Thanks for any help you can give me +++ #10855 From: Russ and Penny Erb Subject: RE: welding and covering > 1) when welding the flap hinges, made up of a tube and small channel > section---the tube gets welded at the channel approx mid point and > down in the channel---how does one weld down in the channel, 1. I tried awfully hard to weld down into the channel and wasn't very successful. It's a corner reflector and blows the flame right back into the torch. Bill Johnson had a better solution as shown on the Bearhawk CD. He cut a hole in the channel at the end of the tube and welded around the end of the tube +++ #10877 From: Benton Holzwarth Subject: Russ Kapes & RE4H6 rod ends Russell Kapes was suggested here as a source for the RE4H6 rod ends. I'd posted two months ago or so that I'd heard from Russell Kapes that he wasn't well, and was suspending his aircraft surplus business. I found a voice-mail this morning saying he was better and resuming business, that he does have the RE4H6 rod ends, still at the $12 price, and described them as 'new takeoffs'. He doesn't have the other rod end types that we need, but his price compares well with the ~ $50 everyone else asks for these, and we need so darn many of them. He prefers a fax'd order with information on what you need and an address to send to. Fax# 847-432-6847. +++ #10890 From: Benton Holzwarth Subject: Re: Russ Kapes & RE4H6 rod ends > how many of these do we need for the BH? These are also known as MS21152-2 Rod End Bearings, used for hinging the wing control surfaces -- 3 per flap, 2 per aileron, 10 parts total. $50 at ASnS, $63 at Wicks in last year's catalogs. +++ #10928 From: Russ and Penny Erb Subject: Flap Y Fitting The plans show a small triangular piece in the flap cable behind the aft cabin bulkhead where the cable goes from one cable to two. I can't find any notations as to the thickness or material for this piece. For those of you who have made this part (or at least thought about it), what material and thickness did you use? +++ #10930 From: "Pat Fagan" pfflyerz@c... Subject: Re: Flap Y Fitting I used .063 for no reason other than that is what Bob called out for most everything else. +++ #10931 From: Russ and Penny Erb Subject: RE: Flap Y Fitting So that would be 4130 steel? Anyone see a problem with using aluminum (less weight)? +++ #10932 From: bearhwk272@... Subject: Re: Flap Y Fitting Go ahead use aluminum just make it 3 times as thick. :), +++ #10951 From: Russ and Penny Erb Subject: RE: aileron bellcrank bushings >> I was wondering if anyone has found a source for the aileron >> bellcrank bushings? (pn mrc r4ff on the plans) I've looked in a/c >> Spruce, Wicks, and Freeman with no luck. > Wicks has them. Page 124 $.42 ea Except it says $9.70 in my catalog (2002). It even says "As used on Bearhawk aircraft". How cool! +++ #11110 From: Russ and Penny Erb Subject: Why you should buy more control cable than you need... and by that I mean enough for a few extra cable sections... Assuming you don't have access to a swaging machine like Bill Johnson, then you will probably be forming your control cables like the rest of us. In general, for each cable you will form an eye around an AN-100 thimble and secure it with an Nicopress fitting. One end will be attached to something using a cable shackle. The other end will be attached to a turnbuckle. The best way to do this (i.e. least weight and parts count) is to pass the thimble through the cable eye end of the turnbuckle, and form the cable eye with the turnbuckle end already on it. NOTE: I highly recommend that you form the end with the turnbuckle end first. Then if you forget to put the turnbuckle end on before forming the eye, you have one more shot to get it right. Otherwise you end up with a very nice cable with eyes at both ends that you can't use for anything, and you probably won't be able to cut one end off and try again because then it will be too short for anything. I'll leave it to your imagination why this little tip came to my mind...hint--it wasn't from analysis... +++ #11284 From: "Jim Dewberry" dewcraft1@... Subject: Water Jet Cutting Source Good Morning Guys, About 6 months ago I found an excellent source for having water jet cutting done. For my business I've used these folks several times and always received excellent service, reasonable prices and quality work - and a "can do" attitude that I appreciate. Water jet cutting is ALL they do. And they'll work from almost any kind of drawing. CAD not necessary. Wow, this is soooo good I ought to charge for this information. (grin) I almost hate to give out this name and address. I really do! After this I'll probably never get their great service again for a long time. But, for the good of this great group of builders, here goes: J.Z. Systems, 1300 Hwy. 77W, Perry, OK 73077 Ph: 800-347-3509 or 580-336-3595 One of the beauties of the way these gentlemen operate is that they will digitize and cut anything you can draw on CAD, graph paper, posterboard or grocery bag. Draw carefully - because what you draw will be exactly what you get. CAD would be best, and of course they have the equipment to read your CAD files, but it's not necessary. Having J.Z. put sized holes in your parts is much extra expense. But, they can pierce the part with a very small hole at the location specified and that gives you a pilot hole for your drilling/reaming. So one layout on the drawing is all you'll need to do. When the parts come in your finishing work is minimum, a little touch up with a file to the burr on the edges. Naturally, small runs are more expensive per part. Get up a quantity order, the price per part drops quickly, and you'll understand why someone invented water jet cutting. When those nice, flat parts come in you'll suddenly realize that laying out parts, all that shop "whittling" and finishing, is akin to snail mail vs. email. They can cut in any material and don't mind doing aircraft work. I don't own any part of the company. That's my disclaimer. >>> 20may03 #11298-18250 +++ #11691 From: "bcschutt" Subject: flap drive torq tube and supports Hey---all this about engines is great stuff--has really got my interest/heart rate up. But I have another problem---the plans call for the torq tube to be supported by a small section of tube with its ID being that of the torq tube OD---metal on metal, no bearing.This is at both the inboard support and outboard support. Has anybody thought of using a bearing and modifying the support assy to house the bearing? or is that overkill? I'm thinking that I might find a bearing with the .75 ID and a minimum OD and change the plans to house the bearings keeping the torq tube centerline at the drawing specified location. Any suggestions? Barry(036) +++ #11692 From: Budd Davisson Subject: Re: flap drive torq tube and supports You're right, it's overkill. bd +++ #11719 From: Russ and Penny Erb Subject: RE: flap drive torq tube and supports Barry--fancy bearings are not required. The torque tube is not spinning at high rpm for long periods of time (it only turns part of a rotation anyway) and it is not in a path that requires minimal friction, such as the elevators or ailerons. What is not shown on the plans but exists on both prototypes, #164 and #232, plus probably many others, is to add a grease fitting at each of the bearing surface. Squirt some grease between the tubes and it is more than adequate. Russ Erb +++ #11896 From: "Schutt, Barry C" Subject: RE: Re: stainless cable > I am searching for 100 ft. of stainless cable, number of strands > unimportant, 1/8" dia, and plastic coated. Might try your local sailboat establishment---good luck Barry +++ #11900 From: "Bruce A. Frank" Subject: RE: Re: stainless cable > I am searching for 100 ft. of stainless cable, number of strands > unimportant, 1/8" dia, and plastic coated. How quickly do you need this? Go to type in the search slot "aircraft cable". The list that appears shows stainless nylon coated as one of the selections. Clicking on that will take you to the cable section where you have several choices of stainless types with nylon or Teflon coatings. My experience with McMaster is next day delivery from their warehouse in Southern CA to my house in San Jose. Bruce A. Frank +++ #11914 From: "Collin Campbell" Subject: landing gear > How did you get the 1-3/8" tube from a circular cross section at the > miter joint down next to the 9/16" tube that the bolt goes through? > On other ends, such as the aileron bellcranks, we heated the tube > and squished with pliers. What did you do to "squish" this large of > a tube. I flattened the ends of the tube by heating and forming with a hammer. You will have to take a "V" shaped notch out of each side first because if you don't the sides will bulge out and make them too wide. This method may sound a little "crude" but actually mine came out really nice, just take your time, heat a little shape a little... Collin Campbell, #370 +++ #11940 From: "newbegin" Subject: Re: Anchor Nuts The plans call for AN366F-1032 anchor nuts to hold the ail. and flap hindge mounts to the respective spars, I have a lot of F5000-3 floating anchor nuts. I would like to use them, any reason why not? Mike would you ask "BOB". I also need to locate six M34-14 rod ends at less than $23.00 (Aircraft Spruce). O/T My neighbor flew his brand new 1925 Travel Air 4000 for the first time last evening, really sounded great. This is a full size replica built from drawings and photos, what a project! Jim #284 +++ #11942 From: Russ and Penny Erb Subject: RE: Anchor Nuts I used K-1000 anchor nuts on the spars. Something about $0.22 each compared to $1.34 each for AN366F-1032A. The F5000-3 should work just fine. I used F5000-06 on all of my access panels and many other places. I like the floating feature even if it is fractions of an ounce heavier. I've had a few problems with K-1000 nuts moving a thousandth or two while riveting and making it difficult/impossible to get the bolt in. Russ Erb +++ #11959 From: Benton Holzwarth Subject: M34-14 rod ends (was: Anchor Nuts) > I also need to locate six M34-14 rod ends at less than $23.00 > (Aircraft Spruce). Try . Click on the "We offer Parts..." link, then on "Click here to open 'the list'". I haven't confirmed yet that it's the same as the part we need, but it looks promising. BEARING M3414M 3/16X1/4 MALE RD END $8.44 Also, I mentioned a while back that Russell Kapes (AT2 Surplus) is handling the RE4H6 Rod Ends again. These need some cleanup, but he sells at $12 vs. $50 at 'Spruce. (That's a different part number than Bob used on the plans, but it's the heavy one used for the aileron and flap hinges. (10 req'd.) Benton 5oct02 +++ #11981 From: pfflyerz@c... Subject: Re: Re:bolts, etc > Have any of you ever made up a list of the necessary bolts and > screws You should know there is no such thing. I started out calculating all my rivets and only buying what I thought I would need. After many Spruce orders I now have 1/4 pound of every rivet there is. Not generally one for scathing insight, I am making the same mistakes with my bolt orders. I recently made yet another bolt order and am already running low on #3 castle nuts and I should have gotten a bunch more metal lock nuts, as well as ... A nut and bolt list is a bunch of those and a few of everything else. Pat Fagan #232 Pearblossom CA +++ #11988 From: "Tim Anderson" Subject: Re: Re:bolts, etc I have always ran into the same problem with bolt lengths. I finally purchased a bolt/nut/washer set (not sure who from) with all sizes. That way, one can usually find the size to fit. The frequently used sizes need to be purchased in, say, qualities of 100 or so. TA +++ #11989 From: "Bruce A. Frank" Subject: Re: Re:bolts, etc I did a similar thing a couple of years ago. Bought one of the bolt kits from Aircraft Spruce. It helped, but I find that the most needed longer bolts are supplied in quantities of 4. Buying additional has pushed the cost of the kit up by half. Still a good investment, if you don't have an FBO who will let you peruse his bolt bins. Bruce A. Frank +++ #14193 From: "barrycschutt" Subject: flap return springs For those of you who have their wings complete or are flying. The question is this----how much tension does one put on the flap return springs at installation? I've had to pull them very tight to have them keep the flaps fully up. Thanks for any help. Barry(036) +++ #14197 From: "Mark Goldberg" Subject: Re: flap return springs Barry (and everyone else), you might have noticed that in the last BearTracks Bob Barrows is now offering a set of stainless steel flap return springs that are engineered & manufactured exactly to the dimensions and strength required for our Bearhawks. The cost is not so great, and has the advantage of being a known material with a professionally engineered cycle life etc. You might consider those. Mark +++ #14260 From: Russ and Penny Erb Subject: RE: flap return springs For me, the simple answer is "tight enough". Of course, my flaps have only been on the wings with the wings in the vertical position. My springs are strong enough to move the flaps to the full up position (which in this case would be pointing straight down). Someday I'll find out if they are strong enough to lift the flaps against gravity. You don't want to show up at the local fly-in or even Oshkosh with droopy flaps. If they don't work, I may then purchase the Bob-springs that Mark mentioned. Russ Erb +++ #14268 From: Pat Fagan Subject: RE: flap return springs I went through several springs before I finally came up with some that worked. I found that I was working against the cable tension, so ensure that the springs are sufficient to hold the flaps up without the cables attached. If so, the problem is that your cables are too tight. The flaps are still easy to acctuate even with a lot of spring tenion. Pat Fagan +++ #14309 From: "Schutt, Barry C" Subject: RE: flap return springs Thanks for the answer. I've installed my springs, but it seems that they have to be quite tight in order to hold up the flaps to the fully retracted position when in the wing normally flat position w/o air moving to help hold them up. The return lever is not in the most advantageous position either which makes the required sprong load even higher. Barry(036) +++ #14534 From: "fourthwedge" Subject: Money Saver - "Eyebolts" This was recently posted to the Starduster BB. "Denny of Oakland" who wrote it, is an AP/IA, FAA Inspector working out of the Oakland, CA FSDO. Might save a dollar or two down the road. "Eyebolts, I assume you mean tie rod or control rods adjustable bearing end assemble. There are several types and styles the streamlined tie rods (AN671 through AN686) are elliptical in shape and are designed for external use where it is important to reduce air resistance. The round and square tie rods (AN701 through AN708) are used internally for various bracing purposes where a light, strong, adjustable member is required. Control rod assemblies with ball-bearing rod ends are used for mechanical systems where low friction loads are desired and where motion tends to twist or bend the control rod. The rod end clevis (AN481) sizes are 0.266 ? inch through 0.141 3/16 inch. The self- aligning, internal thread rod end (AN943 through AN 951) sizes are ?- 28 through 5/8-18 the (AN947 through AN951) has the same sizes. Any of these can be ordered and are standard hardware. If you go to an aircraft hardware supply house the (AN) parts will be very expensive. If I might suggest go to your local tractor dealer they have the same AN parts at greatly reduced prices. Both parts are made by the same manufacture, but one says aircraft the other John Deer. Check the part numbers or the KS bearing number on the part it should match the (AN) part number. The tensile strengths are the same and you can install them on your experimental aircraft. Please be advised I am only suggesting as long as the (KS) numbers are the same and only on experimental aircraft." Denny of Oakland +++ #15414 From: Budd Davisson Subject: Re:trim tabs As long as we're talking about trim tabs: Didn't we have a thread a while back about using vernier cables to do the job? Or was that a conversation I had amongst ourselves at AviPro. To recap: there are a lot of long vernier cables available, especially from the marine industry, that it seems to me would work fine for trim control. I understand some RV's use them as well. Two thoughts come to mind: you could mount the cable overhead, 90 degrees to centerline, put a good sized wheel on it and use it exactly the same way it works now but at a vastly reduced ratio. The cable could either run all the way back to the tail or stop at a bellcrank/walking beam, that could also fine tune the ratio, somewhere in the ceiling. The vernier has the advantage of also have built in friction. Second thought: it could be mounted between the seats pointing up (or forward), and snaked back through the floor. The vernier cables have a lot of possibilities but I just haven't had the time to research them. Do I hear any research volunteers? bd +++ #15415 From: Pat Fagan Subject: vernier trim tab & more flap reflex I am actually quite happy with my lever trim system. It took a little while to get used to, but now I can trim very precisely simply by grabbing the handle closer to the base. It works very well as an emergency elevator control. I still haven't re-rerigged my flaps so they either fly at 0 degreees at 0 notch, or actually deploy in the air at 1 notch. They still tend to trail up about 5 degrees. I spoke with Bob on the phone yesterday about another matter and completely forgot to ask him the question I have about the flaps. We now know aerodynamic pressure is more than sufficient to "reflex" the flaps. Let's say the reflex position is set at 0 notch, where the control arm is resting against the bumper, and 0 flap is set at 1 notch. Since the only thing holding the flaps at 0 is cable tension, the flap cables will be staying stressed at cruising speed, well above flap operating range. Does anyone see this as a deal breaker for reflexing flaps? With the flaps slightly reflexing on their own, and lightly loaded as I am for testing, I can see the elevator counterbalance is raised about 1 thickness, showing slight down elevator at cruise. I imagine with passengers it would fly neutral. I would actually be content to leave things as they are, but since this is test flight time, might as well test. Pat Fagan +++ #15435 From: Russ and Penny Erb Subject: RE: Re:trim tabs No such thread here in my memory. Many RV-4s and RV-6s used a vernier cable for trim. Sounds like a workable option. Instead of using a really long cable, you could also use a really short cable to a bellcrank like I did in my system. I'm not volunteering since my trim system is already built. Russ Erb +++ #15438 From: Pat Fagan Subject: Re: vernier trim tab & more flap reflex > Pat--are you saying that currently your flap cables are stretching > such that the flaps are floating up? Is your flap pushrod not > against the hard stop? To answer Russ's guestion, the flaps are perfectly postioned at neutral with the arm against the stop on the ground, and yet they trail upwards in the air. To duplicate the in flight position, on the ground, takes a significant push on the flap. I assume the bumper is being compressed as well as any mechanical slop, but I would have never believed there was that much force being generated. If you want, Russ, swing by Crystal airport on your way to my place and see for yourself. I am in the south facing hanger. Pat Fagan +++ #15442 From: Tom Marsh Subject: RE: vernier trim tab & more flap reflex Pardon my ignorance, but isn't some reflex a good thing? I've read where go-fast planes design in flap reflex to reduce drag. It sounds like the wing 'wants' to relfex, that it is a more 'natural' position. Please tell me what I am missing. Tom Marsh #596 +++ #15444 From: "shellybird" Subject: Re:trim tabs > Didn't we have a thread a while back about using vernier cables to > do the job? We have used vernier cables on our Hiperbipe, Christavia, Hatz, and Mountain Goat. All were very successful and easy to install, easy to use, and easy to tweak! Our source was a company named Cablecraft, a division of Tuthill. It's been awhile since our last purchase - they used to be in Tacoma, Wa. - but I'm sure you can locate them on Google. If you can't I will go searching. A real quality product. Shelly and Fred (311) +++ #15450 From: Pat Fagan Subject: RE: vernier trim tab & more flap reflex > Pardon my ignorance, but isn't some reflex a good thing? You're right, reflexing is most likely a good thing, I'm just trying to figure out how to go about it using the system as designed by Bob. The system as designed has a bumper to take flight loads on the flap system. If you use the bumper for the flaps in reflex, then the cables are taking flight loads with the flaps at neutral. Don't know if that is a good thing or not. Pat Fagan +++ #15480 From: charles.k.scott@d... Subject: Adjustable flap upstop > Pat, have to talked to bob to see if proto 1&2 flaps reflex at speed > ? Being the smart old fox he is and his attention to performance > and economy this may be part of the design. The Christavia's flap upstop is simply an L bracket welded to the wingside flap hinge, and a similar type L bracket welded to the flapside hinge. It's gratifyingly simple, but has no adjustability in it at all, in case flight testing should show a need. After discussing the situation with a friend of mine, he suggested cutting out a slot in the wing hinge and welding in a threaded barrel that would take a bolt. The bolt, with a lock nut, makes the upstop adjustable, allowing any kind of tweaking necessary to correct for a heavy wing or reflex the flaps. Corky Scott +++ #15707 From: Russ and Penny Erb Subject: RE: Question for Erbman: Mounting Autopilot Servo > To which part of the spar do you intend to mount your autopilot > servo housing? Within the webbing, and/or sparcaps? Look on your Bearhawk CD under Construction Photos | Wing | Autopilot Servo Mount. I built a mount to stand off behind the spar to line up the servo drum with the aileron control cable. In the pictures, the holes have not been drilled for the servo drum or mounting bolts yet. Russ Erb +++ #15726 From: "Mark Conover" Subject: Re: Question for Erbman: Mounting Autopilot Servo Righto, I had seen the photos, but it wasn't clear where on the spar you intend to bolt the autopilot servo mount. Will you drill-out some of the rivets in the sparcaps, then re-rivet with slightly longer rivets to attach the mount? Thanks, Mark Conover +++ #15728 From: Russ and Penny Erb Subject: RE: Re: Question for Erbman: Mounting Autopilot Servo Oh, so that's what the question was! Sorry for the confusion. You're right--the pictures don't show it very well. At each corner of the mount, one of the -5 rivets in the spar cap is replaced with a AN3 bolt and nutplate. So that's 4 AN3 bolts through the cap strips. Russ Erb +++ #15752 From: Del Rawlins Subject: Re: flaps I suppose it is just a matter of time before somebody installs electric flaps on a Bearhawk. A worm drive with a hand crank arrangement located in easy reach of captain and first officer would also alleviate the problems with reaching/applying the flaps without the use of electrons, at the cost of making them super slow to actuate. All I do know is that it won't be me because one of the first things I noticed upon receiving my plans is the close resemblance of the flap handle to the handbrake lever on my MGA. Some things should not be messed with. 8^) Perhaps this would be a good time to mention yet another idea I had for setting flap reflex. I think it would be possible to install another pulley in the flap cable run, that would normally deflect the cable slightly, but when reflex is desired, the pilot would move the pulley (through some simple crank or lever) slightly, putting slack in the system and reflexing the flaps. The benefits would be having all the normal flap settings as designed available, and possibly not needing to reach all the way to the floor to reflex the flaps, depending on where the reflex control is located. The disadvantages being the extra weight and complexity. -- Del Rawlins +++ #15760 From: "Mark Conover" Subject: Electric Flaps (was Re: flaps) I'm interested in using a Motion Systems actuator. See link below. I haven't figured out whether the 40 or 100 pound unit would be necessary. Guess it depends on whether the actuator uses a horn for advantage (like the flap handle in the original design), and the dimensions of the horn. While I will definitely be using a MAC servo for elevator trim, I am undecided about removing the flap handle. My first airplane was a Cessna 140. Even though its flaps were about as effective as holding a legal pad out the window, I would once in a while deploy them, just for a change in routine. There's something appealing about grabbing a big lever. Or, in the case of the Bearhawk, removing the shoulder belt, folding oneself over like an yogi, and then pulling up the flap lever. :-) Here's the actuator link: http://www.motionsystem.com/85915/85915-1.htm I may be mistaken, but at least one or two other B'hawkers have mentioned using such an actuator. Mark Conover, #502 +++ #15766 From: Holger Stephan Subject: Re: Electric Flaps (was Re: flaps) A fellow BD-4 driver told us once that he likes the manual flaps actuation because he can very quickly retract them after touch-down on his short-field home strip and put more weight on the wheels for effective breaking. - Holger +++ #15778 From: Ken Beanlands Subject: Re: Electric Flaps (was Re: flaps) This is particularly useful on floats. I've made a number of take-offs where I used the flaps to geth the plane on teh step, retracteded tem again until I hit about 55-60 mph and then yanked them on to pop the plane off teh water. Very effective at breaking the surface tension. You can pop to about 30 degrees aof flap to pop it off and lock them in at 20 for initial flight in ground (water? ;-) effect before easing them off for climb. When I've done this, I use the flap actuation as my decision point. If it doesn't come off, I cut the power. I only had to do this onece so far. Ken Beanlands B.Eng (Aerospace) +++ #15789 From: Russ and Penny Erb Subject: Flap cable fitting interference? To Pat Fagan and anyone else who has worked out your flap cables: I've installed the flap cable pulley per the plans. While testing the cable, using a cable with a nicopress swage around a thimble plus a shackle makes a fitting long enough that it seems to rub and jam against the rear spar and fitting at full flaps. Has anyone else had this problem? Right now the only solution I've thought of is to order a cable with a MS20667 Fork End swaged on one end. This would be shorter than the nicopress mess, and presumably less likely to jam. It wouldn't be that unreasonable, since Spruce charges 4.95 to swage a fitting on one end of a cable when length is not critical. Russ Erb +++ #15791 From: "collinc2002" Subject: Re: Flap cable fitting interference? I encountered the very same problem, and I am doing what you propose. I ordered cables with the swaged fitting on one end, nothing on the other so I could fit to length. Spruce apparently has quite a backlog of orders, as I ordered mine at least 3 weeks ago and they haven't arrived yet. Collin Campbell +++ #15918 From: Pat Fagan Subject: Re: Flap cable fitting interference? > makes a fitting long enough that it seems to rub and jam against the > rear spar and fitting at full flaps. I don't recall having this problem. It could be because I didn't weld the control arm to the flap torque tube until until I had installed the wings, so may be I was better able to exploit the nitch between the spar and bracket. I can't remember exactly the relative positions of the pieces which is why I am not sure. Also, I placed the pulley at whatever postion would make it all work. Pat Fagan +++ #15922 From: Russ and Penny Erb Subject: RE: Flap cable fitting interference? I looked at a picture I took of your airplane. Your flap lever is installed rotated farther forward than shown on the plans, which might make the first notch of flaps harder to deploy but should avoid the cable running into the spar. It appears the swage fitting isn't going to solve the problem by itself. Looks like I'm going to have to pull the torque tube out, weld the bolt holes shut, sand smooth, and readjust the position of the holes. I'll look at changing the initial angle more like yours and shifting the horn outboard slightly to line it up better. May need a few mods to the pulley mount. May have to Moto-tool out some of the spar root like shown in Bear-Tracks a few years ago. But, hey, I've solved similar problems before, even if it meant rebuilding everything. Yea, it sux doing it, but when it works right, it all seems worth it. Such fun... Russ "Here we go again" Erb +++ #16243 From: Russ and Penny Erb Subject: Fairleads in Wing Struts For Pat Fagan-- You put a fairlead at the top end of at least one of your wing struts for the aileron cable. I just cut the hole for my cable, and it looks like I will have the same problem of the cable rubbing the inside of the strut. My question: How did you secure the fairlead in the strut? Russ "It's easier to ask than to try to figure it out myself" Erb +++ #16244 From: pfflyerz@c... Subject: Re: Fairleads in Wing Struts > My question: How did you secure the fairlead in the strut? A big gob of silicon. I wasn't sure if it would work, but figured it couldn't hurt to try. It hasn't budged. Pat +++ #16245 From: Russ and Penny Erb Subject: RE: Fairleads in Wing Struts Cool! A microprocessor? Or would that be silicone adhesive? What do I look for at the hardware store, since there seem to be a lot of products with "silicone" on the label? Did you attach the two halves of the fairlead together with anything other than the silicone? I hope you never have to remove that cable--you'll have to cut out the fairlead. Then again, that probably wouldn't be that big of a deal. Russ "Feeling pretty clueless right about now" Erb +++ #16249 From: pfflyerz@c... Subject: Re: Fairleads in Wing Struts > Did you attach the two halves of the fairlead together with anything > other than the silicone? I clipped the two pieces of the fairlead together with the spring clip, just like you would normally attach them. It was kind of a pain thogugh since there was no structure to work against, to hold the halves in place while working with the clip. I dropped the clip down the strut numerous times and had to walk over and pick it up under the plane. The silicon I used it the clear RTV sealant you get at the auto parts store. Pat Fagan +++ #16932 From: Del Rawlins Subject: flap pushrod bushing The flap pushrod (drawing 12) requires a bushing with a 3/16" ID and a 1/4" OD, and I am drawing a complete blank when it comes to finding some bronze bushing stock in this size. Was wondering if anybody had any suggestions, thanks. -- Del Rawlins +++ #16933 From: Sam Butler Subject: Re: flap pushrod bushing Buy some a with a that's to small ID or too big OD and find someone with a lathe and turn it down, is one idea. Sam Butler +++ #16934 From: Russ and Penny Erb Subject: RE: flap pushrod bushing I increased the size of the crosstube on the pushrod to 7/16x.058 and used a 5/16x.058 4130 tube for the bushing (actually I think I used .063 thick but had to sand down the tubes to fit--I'd recommend the .058 now). I don't see that there is enough rotation in this joint to justify a bronze bushing. As I see it, the bushing is there just to tighten the bolt down onto and leave the pushrod free to rotate. Russ Erb +++ #16935 From: "Rod Smith" Subject: Re: flap pushrod bushing Have you tried Wicks Del, they seemed to have a pretty good selection of bronze bushings, don't have my catalogue handy right now. Rod Smith #246 +++ #16936 From: bearhwk272@a...> Subject: Not a bronze flap bushing. Bushing stock, this sound wierd, use 1018 or 1020 Cold Rolled Steel. The primary purpose of this bushing is to keep the welded 4130 flap actuating rod off of the bolt. Both are from the same material and similar in hardness so they will tend to gall together. The CRS material wil provide enough hardness separation and is soft enough that it will perform the same function as bronze, just keep it lubricated. This is utilized in many aircraft applications. Kevin +++ #16939 From: Del Rawlins Subject: Re: flap pushrod bushing > Have you tried Wicks Del, they seemed to have a pretty good > selection of bronze bushings, don't have my catalogue handy right > now. Yeah, I tried both the Wicks and Spruce catalogs, MSC, and a couple other online places. It wasn't a total loss, however, since I stumbled upon a really good MGA tech site cause they were talking about all of the bronze parts in the transmission. 8^) My Wicks catalog is a couple years old so maybe when the new one arrives they will have more of a selection. The point about using mild steel to bear against the harder AN bolt makes sense. I would still like to use oilite bronze to dispense with the need for lubrication. It may not need much lubrication but in the unhappy (but possible) event that my Bearhawk has to sit outside in the Alaskan winter, particularly on the coast, I'd like for as many of the less visible/accessible parts as possible to not need lubrication. I've got to get me a lathe at some point, but it's fairly low on the tool priority list right now. -- Del Rawlins +++ #16947 From: Pat Fagan Subject: Re: flap pushrod bushing It's been a while, but I believe I got those bronze bushings from Motion Industries. They didn't have any long enough for the cross tube, but two short bushings worked perfectly. Pat Fagan +++ #17495 From: "Vuxton, Christopher" Subject: RE: Re: Flap & Aileron Rod end bearings > The parts were drilled off whatever they were attached to, and the > grease is dry and the green paint is flaking off, but they look like > they'll be usable. I got these rod ends and for the most part (one is a little egg shaped) they are good. I stripped the paint and got a regreaser from Aircraft spruce (offer still open to rent the degreaser...$5.00 check made out to "Make-a-Wish Foundation" plus $.55 in stamps). Chris +++ #17506 From: Dan Shilling Subject: Re: Re: Flap & Aileron Rod end bearings I received 10 of said bearings about 3 weeks ago from Russell Kapes, and it took about 3 months to complete the transaction. I sent a couple of faxes and thought I would never hear back from him, when out of the blue he returned a fax saying his machine had run out of paper some time ago and he just found my fax sitting in memory. Hmmm... He wanted to know if I still wanted them, so I sent a couple more faxes saying "yes" and they finally came. Not new (no noticeable wear) and not pretty to begin with, but they cleaned up just fine. He never said anything about the price except just to send a check when I get them. Dan Shilling +++ #17546 From: "Kevin Griffith" Subject: Rod Bearings I have purchased rod end bearings from Russell. It took awhile to make connection with him but eventually he mailed the bearings and then I paid him $12 each. I cleaned them up and with a little grease will be like new. The bearing shafts (for lack of a better term) have two hole sets 90 degrees to each other where the bearing was riveted to the original structure. My dilemma is should I attempt to use those holes and how would I located and drill the hinge tube? Or should I simply relocate and drill new rivet holes away from the existing holes. Would that many holes excessively compromise the strength of the shaft of the bearing? Any input would be greatly appreciated. Thanks Kevin +++ #17551 From: Budd Davisson Subject: Re: Rod Bearings > The bearing shafts (for lack of a better term) have two hole sets 90 > degrees to each other where the bearing was riveted to the original > structure. My dilemma is should I attempt to use those holes... Drill your new holes anywhere but where existing holes are. It's next to impossible to match those holes because they are inside the hinge tube and you can't see them. The bolts see virtually no load so excess holes won't be desirable but they won't be a problem either. bd +++ $Id: 2.1.7-Wing-Brackets,v 1.16 2003/05/21 15:02:07 bentonh Exp $