+++ #51 Subject: Re: Flap Springs From: Terry Pierce > The plans define the flap return springs as '1/2" springs 20#'. I > understand 1/2", but an anyone tell me what the 20# means? Apologies if you've already received a bunch of private replies. I assumed that this meant "20 pound" springs. My question is, at what length should they be fully extended to where they will develop the 20 pounds of force? My guess is that it doesn't matter a lot as long as they have enough extension. A good guess might be pounds per inch extension. +++ #256 Subject: It's an 8 lb flap! From: Russ Erb Finished riveting together my left (first ) flap yesterday. So nice to finally have an assembly that looks like a recognizable airplane part. All of that effort over the past years to precision cut the ribs and keep everything just so really paid off. The parts went together with a minimum of fuss and came out very straight and true. Most kewl! More empirical data of the mildly useful category: My uncovered flap frame weighs just under 8 pounds. +++ #541 Subject: Re: Rod Ends From: gdanfor- > Has anyone found a good source for the MS21152-2 Rod Ends used on the > flaps and ailerons. I know Aircraft Spruce has them for about 50.00 US > each. when you convert that to Canadian every dollor helps I purchased mine from B&B Aircraft Supplies 31905 W. 175th St. Gardner, Ks 66030 Attn: Dan Brown (913)884-5930 They are used but tight and no obvious wear. I think they come from rebuilt Military stuff but they after the removal of the od paint in perfect condition and I don't remember for sure but they were only a few $$ each. He also has the Cessna style trim wheels that the plans call for. +++ #550 Subject: Inspectable Rod Ends From: Russ Erb Kevin's points on quality rod end bearings reminded me of something that I saw on the Prototype Bearhawk. Bob installed some cover plates over the large cutouts around the hinges on the flaps and ailerons. What I have a problem with was that these cover plates were attached with blind rivets. My opinion is that the rod end bearings used for hinges should be inspected at least once a year at the annual inspection. This would require drilling out the blind rivets. Instead, I intend to use screws to attach these cover plates. Unfortunately, I realized this after riveting on at least one skin to a flap, so it was too late to install nut plates on the other side of the skin. Therefore, I plan to use rivnuts to anchor the screws. +++ #553 Subject: Re: Inspectable Rod Ends From: bearhwk27- I had similar thoughts with respect to the blind riveted inspection / fairings. Further thought and reflection is that I liked the method because there are no pesky PK screws to back out and come loose, which on the aileron locations could cause a jamming of the control surface. I may go the rivnut route if I can find self locking variety. +++ #554 Subject: Re: Inspectable Rod Ends From: Russ Erb I don't know if the rivnuts commonly sold by Spruce or Wicks are "self locking." If not, consider 1) using Loc-tite on the screws, and 2) screws backing out should be apparent during the preflight inspection. +++ #555 Subject: Re: Inspectable Rod Ends From: Mike Meador OK guys - Let's not get too carried away with a couple of pieces of aluminum. The rod ends are very visible for a pre-flight and easy to maintain. You could just use lexan if it is something that you really want to look at. We drill out the rivets when needed - they are the best - lightest - simplest - fasteners that you can use in this area. Normally you would only have to take off a top or a bottom coverplate to entirely remove the aileron or the flap. The rivets that we use have a painted head (white) so they match right up (close enough anyway) with the painted coverplate. Do what you want to, but don't make it too much more involved than it has to be. +++ #959 Subject: Flap spring purpose? From: Russ Erb The part you missed is what is between the flap arm at the root of the wing and the flap handle. Answer: a cable. The flap handle can only extend the flaps (tension on the cable). The flaps are retracted by the springs and air loads. In fact, in flight I suspect the springs aren't even needed--the air loads would be sufficient to keep the flaps up. Therefore, in my opinion, the purpose of the springs is to keep the flaps up on the ground. Don't be fooled by that "20#" on the springs. We've never really gotten a good answer out of Bob Barrows as to what that means. What we have gotten out of him is that the springs to use are common screen door springs from the hardware store, modified to the right length. +++ #969 Subject: Re: Flap spring purpose? From: george velguth Darn! Someone saw that flap spring post before I could delete it! ;) I realized immediately after I'd posted that I'd probably better check a few more drawings. Sure enough, there was that single flap actuation cable. I returned to the site and deleted my question, but you were too quick, Russ. My other question still stands, however. Why aren't the flaps powered (manually, of course) up as well as down? I just don't like the whole concept of spring powered retraction. I'm sure it wouldn't be too dificult to modify the actuation system to provide rigid control. I'll have to start thinking about that. (Not that I'm anywhere near having to make a decision!) Another question about the spring retraction system, why not just attach the springs to the (modified) control arm attach hinge/bolt/boss/assembly/whatever? Not only would this eliminate the need to fabricate separate spring attach bosses, it would also provide the springs with a somewhat longer arm to pull against, thus making them more effective. +++ #971 Subject: Re: Flap spring purpose? From: Russ Erb > My other question still stands, however. Why aren't the flaps powered > (manually, of course) up as well as down? I just don't like the whole > concept of spring powered retraction. I think you'll find the air loads on the flaps are more than enough to raise them. > I'm sure it wouldn't be too dificult to modify the actuation system to > provide rigid control. I can't agree--I think it would be far more effort than it's worth. The system as designed is wonderfully elegant and lighter than a forest of push-pull tubes, rod ends ($$$), and bellcranks that would be necessary to provide rigid control. +++ #977 Subject: Re: Flap spring purpose? From: george velguth I'm sure you're correct about the airload being sufficient to raise the flaps in flight, and probably about the folly of trying to modify a perfectly good system to "correct" a non-problem. My dislike for spring retraction comes from the oft-repeated experience of moving the Citabria flap handle to the retracted position while on the ground, only to see the flaps remain extended. For what its worth, I was thinking not of push-pull tubes, but of a second cable. +++ #1206 Subject: Rod Ends From: Gord Trites I have been pricing the MS21151-2 rod ends and the best price so far is Aircraft Spruce at $49.95. Checked with B&B Supplies and a bunch of other AC salvage yards with no luck. At 49.94 +exchange+duty+tax+++ Canadians seem to have a lot of +s It's over 800.00. So I have an idea for you engineer types? Could I welded a bushing into the alieron and flap hinge mount, so they would except a MD46-15 male rod end (1/4 bore 3/8-24 shank) page 139 AS catalog. and go with that ? A little food for thought. +++ #1207 Subject: Rod Ends From: Russ Erb Message text written by INTERNET:bearhaw-@egroups.com > I have been pricing the MS21151-2 rod ends... Gord--I just mailed your Bearhawk CD today. On it you will find several discussions of rod end bearings, including the following one from April 1998. I hadn't really paid much attention to the discussion on the price of rod end bearings, just hoped some of you would find a solution before I needed them. I was looking at the plans last night, sheet 13 and don't see how the bearings are attached to the hinge mount. I see what looks like two 1/8" perpendicular holes but no reference to fasteners. Just curious at this point. One thought for cheaper bearings would be to make the hinge mounts using 5/8" bushing stock and tap it for a 3/8" male rod end bearings, $29 instead of $55 in Aircraft Spruce. Guess that would add some weight to the installation. Just a thought. Rod Smith I checked with Bob on this and he said that he would not recommend this. The bearings used on the flaps and the ailerons recieve a lot of side loads and the thread is a stress area that would be prone to cracking. You might find out if the thread is cut or rolled onto the bearing If it is cut then you DO NOT want to use it for sure! Cut threads should only be used in push-pull applications. +++ #1213 Subject: Re: Rodend Bearings----- A source? From: Mike Meador This topic comes up every so often as well it should. This is just one of those items that you have to attend fly-ins to get a really good deal on. I have picked up the rod ends for as little as $5 and seen them for as much as $25 at the fly-ins. They usually average about $10-15 most places in new condition (installed on a rod of some sort most of the time). We have managed to direct every builder who comes to us at the fly-ins to a vendor that has an acceptable selection and price. There are several variations of the rod ends out there that will work but they still have to be of the same style spelled out in the drawings. I think that Russ got some at Sun N Fun that were not the exact MS number but of the correct style. Right now I have 10 (all mine - not for sale) that I picked up for $7 each, new, in the box from a fellow who did not know what he was selling. Sun N Fun seems to be the best location for these little guys. +++ #1215 Subject: Re: Rodend Bearings----- A source? From: bearhwk27- Have a couple of ideas on the rod end issue. 1. I will be willing to excersise my bulk purchasing power thru my employer for the exact rod end called out. The more I purchase the greater my discount. These would be new, not surplus. ( part of the reason for the obscene price on these units is that they are not in current production and are of a superseded mil spec ) 2. Find an equivalent current Mil Spec and make the required mountings (With Bob's blessing ) 3. Manufactuer the rod end to Bearhawk requirements utilizing Mil Spec bearings and 4130 rod end. ( With Bob's Blessing ) 4. Manufacture the parts to the Mil-Spec drawing. I have the blueprint, it's in the public domain. How many takers? What do you think is a realistic figure that you will antie up for new Aircraft Quality parts? Let me know +++ #1220 Subject: Re: Rodend Bearings----- A source? From: Russ Erb > I think that Russ got some at Sun N Fun that were not the exact MS > number but of the correct style. This is true. At Sun N' Fun 99 I had the priviledge of being dragged by...well, okay, led by Bob Barrows himself to a vendor who had what sure looked like the right rod ends. Bob told me that these were the ones I wanted, so I figured they must be the correct ones. Well, they definitely were of the right style, and I have every confidence that they will work. However, they were not the exact MS number called for. The shank was a few thousandths smaller (not a convenient fractional size--may be a millimeter size (?)), and the distance from the end of the shank to the bearing was different. The length of the bore was slightly longer. FORTUNATELY, I had not made the hinge mounts yet, nor had I attached the hinges to the flaps or ailerons (still haven't...) yet. As a result, I was able to recover. I used a slightly thicker tube to accept the shank, changed its length to account for the shank, and will have slightly different locations for the hinges on the flaps/ailerons. Even then, I will need a .003 steel shim (the thickness of a Coke can) tightly wrapped around the shank to take up the remaining slop. If I were doing it again, I would carry with me the MS number of the rod end bearing I needed, its important dimensions, and my dial calipers to measure the rod end bearing to make sure it was what I wanted. Easier than redesigning everything. You might also want to consider buying your rod end bearings before fabricating the parts to go around them if you plan to use a "suitable sub". Unless you can find the correct rod end labeled with the MS number, use extreme caution buying any other similar rod end bearings unless you can buy all 10 of them at once. You may not be able to find an exact match elsewhere if you don't know exactly what you have. There is room for "suitable substitutes" but it carries additional risk with it too. +++ #1225 Subject: Re: Rod Ends From: Gary Danford I'M also changing a few things to get away from the expense of the rod ends. I found some from B&B Aircraft for the flaps etc. I'm changed the rod ends on the control sticks to female that cost about 6.00 each and am using a solid rod between. An extra weight but a 90.00 savings. Sometimes you have to give up a little. +++ #1227 Subject: Re: Rodend Bearings----- A source? From: Daryl Van Zee > 1. I will be willing to excersise my bulk purchasing power thru > my employer for the exact rod end called out. > 2. Find an equivalent current Mil Spec and make the required > mountings. I think it makes more sense to find the current spec equivalent and redesign for it if you have access to that info. That way we have an alternate mount if the surplus ends are not available. +++ #1245 Subject: rod ends From: Tim Anderson I can't resist to temptation to continue the rod end conversation. I am no where near constructing to the point where the flap/ailiron rod ends are needed, but...... I looked at the drawings and am a bit be-futtled (confused). The rod ends (MS21151-2) apparently fit inside the mounting tubes. Does one weld or bolt them in place? If so, you can't fine tune the distance to insure proper alignment as with threaded type. This can't be right. Maybe I'm missing something. If you all answered that yesterday during your rod end conversation, I must have missed that point. +++ #1261 Subject: Re: rod ends From: Bill Cox > I looked at the drawings and am a bit be-futtled (confused). The rod > ends (MS21151-2) apparently fit inside the mounting tubes. Does one > weld or bolt them in place? If so, you can't fine tune the distance to > insure proper alignment as with threaded type. This can't be > right. Maybe I'm missing something. The rod ends are aligned by fitting the control surfaces to the wings. The rod ends are riveted to the tubes. Mike wrote a good description of Bob's procedure sometime last year. If you don't find it I will send you a copy. +++ #1265 Subject: rod ends From: Russ Erb > I can't resist to temptation to continue the rod end conversation. From the July 1999 Bear-Tracks: "2) The second tip has to do with the rod ends. It is recommended that you Loc-Tite the rod ends into the hinge mounts on the final fit after welding and painting. If all checks out well rivet the rod ends in place with two 5/32" AD rivets. " From the Archives: May 1999 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? 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 possible. 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! Ain't it great to have all of this stuff archived? Now all you've got to do is to figure out what heading I put everything under... +++ #1268 Subject: Rod End Search Status From: bearhwk27- Enough positive responses have been received that I will find a source for New Mil Spec Rod Ends. It may take two weeks to nail down a price and lead time but with the responses totaled up it is nearly 200 pcs in a bulk order. This quantity is large enough to get someone's attention and a reasonable price, if one is to be had. I will firm up a list with specific commitments after finding out where the price ends up. Thanks for your responses. +++ #1291 Subject: I've been robbed. From: Float-By Shooter Today I received in the mail some stuff including one rod end I had ordered for use in jigging up my hinge mounts. Not having seen one before, I was not exactly sure what to expect. I am totally underwhelmed by what I have received for my fifty bucks, it is one of the more unremarkable looking parts I have seen. It doesn't even have a grease fitting. You would think for $50 it could have included a grease fitting or even had a shinier finish or something to justify the cost. Outdated mil-spec or not, I can't see any reason for those bearings to cost anywhere near what they do, so I hope the group purchase works out. But no pressure Kevin! 8^) +++ #1293 Subject: Re: I've been robbed???? From: bearhwk27- With respect to the rod end bearing that you purchased was it the MS21152-2, MS21151-2? How much was it? Was it Aircraft Spruce and Speciality? I only have a 1995 catalog and it shows about $ 37.00. I have located 2700 of these critters but every one is proud of their prices. Most factories have not run this part since about 1997. Two reasons that these units are pricy. 1. They are a dual row ball bearing supported spherical motion inner race. 2. They were created to be low friction aircraft control bearings. ( READ THE ABOVE..........HIGH PRODUCT LIABILITY AND LITIGATION) Still working the issue. +++ #1294 Subject: Re: I've been robbed. From: zippydog- I was going to look it up, but since you are on line, did you develop an AUTOCAD compatible drawing of the wing profile? I recently acquired Release 14 and the use of a plotter. Although I transferred the profile by tracing by hand, I thought others might want a "duplicate" of drawing 7, on paper, that they could glue to the form blocks. I think I'm like a lot of guys who doesn't want to destroy drawing 7 so that the plans package remains complete. +++ #1297 Subject: Re: I've been robbed???? From: Float-by Shooter > With respect to the rod end bearing that you purchased was it the > MS21152-2, MS21151-2? MS21152-2 hollow shank, MRC# REP4H6 > How much was it? $49.95 > Was it Aircraft Spruce and Speciality? Yes. > I only have a 1995 catalog and it shows about $ 37.00. The price I paid is as printed in the 1998-99 catalog. The solid shank (MS21150-2) is listed at $52.00, so no savings there. Is there a way of getting some grease to them periodically? Preferably without disassembly. +++ #1332 Subject: Re: Rod end bulk purchase, Can we wait? From: bearhwk27- Before I go forward on the rod end bulk order issue I will get a true head count, and will have a final fixed price. Do not think that a wee bit of a wait will compromise either the tight building schedules or rod end delivery. +++ #1424 Subject: Re: Hands, entry and exit ..Bearing status From: bearhwk27- Rod end bearing story still unfolding but best price is just shy of $ 40.00 ea. Have been quoted as high as $ 57.00 ea. More later on progress +++ #1597 Subject: Rod End - Taking Orders From: bearhwk27- Here is the best that I was able to put together for bulk order of rod ends. New MS21150-2 $39.80 ea ( US Dollars ) These are the solid shank version of what Bob specified in the plans. This rod end is an aircraft control system rated bearing. Construction is 4130 body, 52100 inner race and balls. Greased and sealed with a PTFE seal ( Teflon ) Delivery of items to your door will be 3 weeks after I have collected orders for 100 pcs. This pricing applies to 100 pcs lot orders. If you wish to order please e-mail me at. deut370-@aol.com I will collect a head count and then work out a payment method. Maybe half when I place order, balance COD. or something, we can figure individual details per lot order. Shipping via UPS about $ 8.00 Will ship these "Gifts" to Canada, also they make excellent cake decorations. Keep me posted +++ #1641 From: Kelvin Gurney Subject: [Bearhawk] Flap Rod ends I've found some of these bearings for $31.25 each. Is this a good price? If so I think these would work for the two flap push rods rod ends. The difference being the plans call for a 5/16-24 shank and these have a 3/8-24 shank. The push rod is a 1/2x.049 which has a I.D. of .402. Weld in a 3/8-24 nut instead of the 5/16-24 nut and it should fit. They are at http://www.hpaircraft.com/special/re3m6-2n/ +++ #3026 Subject: The 20# spring mystery solved! From: Russ Erb Something else that Bob told me at Oshkosh. The "20#" notation on the flap return springs means that each spring should have 20 pounds of pre-load. That is, it should take 20 pounds of force to stretch the spring onto its mounts. Mystery solved. +++ #3178 Subject: Flap/Seat Interference From: Rod Smith > Incidentally, we found a minor glitch everyone should think > about. With my seat well forward, the flap handle hit the edge and > stopped me from getting the last notch of flap. The seats only > have to be another 1/2 - 3/4 inch further apart to clear. I just noticed again the 4/97 plans revision that moves the location of the flap lever forward one inch. Was Proto II built according to the revision or the old dimension? Mike? +++ #4081 From: Corky Scott charles.k.scott@d... Subject: Re: [Bearhawk] Digest Number 241 Reflexing flaps. I'm not building a Bearhawk, I'm building a Christavia which is pretty similar except for the fabric wing it uses instead of the aluminum wing. I chose to adjust the flaps in a manner that might be of interest to the group. The Christavia has an unusual hinge line for both the flaps and the ailerons; it's offset back from the trailing edge everal inches and is about 3/8" below the bottom of the wing. The leading edge of the flap/aileron is shaped like the leading edge of a wing. The trailing edge of the wing is shaped aerodynamically to smoothly slot air between it and the leading edge of the flap/aileron. With the hinge line below the wing, when the appendage is deflected downward, it moves away from the trailing edge of the wing and opens up the slot. This causes high pressure air from below the wing to slot through the opening and attach itself to the top of the flap. This is designed to make the flaps and ailerons more effective when deflected down. When the ailerons are deflected up, the hinge moment causes the nose of the aileron to stick out into the airstream making it a Friz type aileron. This and a differential shaped aileron horn (shorter on top than on the bottom) is supposed to reduce adverse yaw to a minimum. The designer also suggested that the flaps and ailerons be rigged at 3 to 5 degrees reflexed and that's what this comment is about, how I did that. The Christavia, like the Bearhawk is a pretty simple airplane. The flap upstops are a case in point. The plans called for you to measure where the trailing edge is supposed to be, clamp an L piece of metal to the trailing edge hinge which hangs down off the trailing edge and weld it in place. You do the same kind of thing to the flap hinge so that the L piece has something to hit. This creates two problems for me. If when welding something shifts, I'm going to have a lot of grinding to fix the situation. If I decide that the angle I settled on is not correct, I've got a lot of grinding to do. And testing would have to occur with non painted parts so that I don't have to blast off the paint, grind off the L bracket and reweld. I thought there had to be a better way and there was. I wish I could claim this was really my own idea but it really belongs to a friend of mine who flies a Waco and is really good at solutions. He thought that the way to get some adjustment at the flap upstop was to weld in a threaded barrel into the trailing edge hinge and use a bolt that can have a stop nut on it. This way you can infinitely adjust the flap, within a certain range. So now, I can rig the ailerons to a reflex setting and match the flaps to that setting. Should this prove to be not the best setting, all adjustments are easily made. I don't know if this is applicable to the Bearhawk or not. I had to cut out a section of the trailing edge hinge, and weld the threaded cylinder in place. This had to be situated such that there was room for the stop on the flap hinge to hit the head of the bolt when the flap was roughly at the right angle for "stowed". From there I would then crank the bolt either in or out for final adjustment and lock it in place with the lock nut. There are three hinges for the flap, as well as the aileron, two of which were required to have stops. In other words each flap needed two stops, which were placed on the outer hinges. +++ #4088 From: budd davisson Subject: Re: Reflex > My plan is to rig the airplane with no reflex initially. > After doing all of the flight testing, if it looks like reflex > may help, I can look at it then. we're putting reflex abilities in the kits and we'll have a demonstrator flying in a year or so and should be able to answer the question of where it's applicable. +++ #5143 From: Budd Davisson Subject: Re: [Bearhawk] Airfoil The BH uses a slightly modified 4412 which, obviously, is picked for it's slow speed capabilities. As you may have picked up from some of the earlier posts, it is the wrong airfoil for optimized cruise because at 23 square with the 0-540 the airfoil is a solid 2 degrees nose-down unless the airplane is really loaded. At Oshkosh, when I flew it, we had about 400 pounds of stuff in the back, and the airplane flew airfoil level at exactly the same TAS (155 mph) as when nearly empty. Bob worked out a small linkage change (I think 3/16" longer) in the flaps so that those who want, can reflex the flaps a couple of degrees to load the wing at higher speeds. As the only one in the group who has any flight time in the BH, I'll guarantee you it's gonna be a real hoss on floats! >>> 4sep02 #9154-11297 +++ #9464 From: Russ and Penny Erb Subject: RE: Digest Number 737 > Hi guys, got a question that probably has been covered and I'm to lazy > tonight to dig out the BH CD. how critical is the space of 2 3/4" > between the flap nose ribs. Sonny--I think you're very likely to have a major problem. I made my flaps and ailerons with the spacing shown on the plans, and I can't get the "proper" length bolt in the hinge. I'm having to leave out the normal washers and I'll barely be able to get the castle nut on all the way. Then again, the "bore" of my rod ends is slightly longer than on those called out on the plans. You need to get out the flap hinge brackets (the "L" brackets), put them in the proper place with the rod end, then see if you can get a bolt in the hinge that is long enough to get all of the way through and have a nut properly safetied. If you can, you'll be okay. If not, you'll have to change something so that you can. To summarize, the constraint on the width of the hinge cutouts is being able to insert a bolt long enough to go through the hinge. Russ Erb +++ #9466 From: "Collin Campbell" Subject: Re: Bolt length in ailerons You wrote about the spacing between the nose ribs on the ailerons. As Russ pointed out the spacing must be enough to be able to install the hinge bolts. If you find the spacing is too close, my suggestion would be to drill a relief hole large enough for the head of the bolt to back up into in one side of the ribs. This would allow installation of the bolt and you wouldn't have to scrap anything. +++ #9475 From: sonny cilley Subject: Re: Digest Number 739 Hi Russ, thanks for the info on the hinge bolt problem, I guess it'll depend on whether it is feed from the inboard side or out board. I'll check out the room I have and let you know. I think that I'll probably end up making another flap spar and doubler plate. I that is all I have to replace because I screwed up something it would be light. actually I have screw up more than just that ,but we won't go into that :-) I guess AC 43 would tell me what I need to know too. thanks, Sonny #234 +++ #9484 From: sonny cilley Subject: Re: Digest Number 740 Hi Collin, thanks that is a good idea about doing a hole so I could back off the bolt in the nose rib . the other thing I thought about was to joggle the nose ribs in this one flap hinge pocket , 1/8" on each one so to get the 2 3/4" spaceing. the problem began by me making the aluminum angle irons 1/2" before the bend radius .that made the parts and the thickness of the nose rib about 5/8 ". there fore shrinking the pocket to 2 1/2 " . so to fix the next 5 flap hinge pocket openings, I plan on makeing 5 new backer plates for the flaps, they shall be 4 1/16 " x 4 ". I'll just have to fiddle with this one pocket and I'll be home free. +++ #9487 From: Russ and Penny Erb Subject: RE: Digest Number 740 The reason I didn't suggest the hole (though I thought about it as a solution to my problem) was eventually the surface has to be covered, and normally any holes like that would be covered, and the hinge bolt is installed after covering. You'll need a hole in the fabric to make this work. I'll leave it to you to decide if that is acceptable for you. Russ Erb +++ #9488 From: Del Rawlins Subject: hinge bolt clearance One potential solution to insufficient clearance for installing your hinge bolts, might be to install the hinges to the rod ends first, and then bolt the hinges to the ailerons. It would probably be a real pain to get any kind of tool in between the wing and the aileron, but it might be an alternative to going without washers or using a thin nut or whatever. It would also be much easier to safety the hinge nuts without the aileron in the way... +++ #9489 From: Russ and Penny Erb Subject: RE: hinge bolt clearance That is exactly what I had in mind. I wasn't thinking so much of doing it to save an otherwise improperly made part, but more for a case like yours where the hinges ended up farther apart than the plans show due to the rod ends you used. Perhaps if you deflected the aileron to its upper limit when tightening the bolts from the hinges into the aileron spars you would be able to get a socket and extension in there. +++ #9492 From: Russ and Penny Erb Subject: RE: hinge bolt clearance For normal deflection of the aileron, I don't think you could get a socket in there. HOWEVER, if the pushrod is disconnected, there MIGHT be enough room to get the tool in. Hadn't thought about that before. I'm not concerned about mine, as they've already been on and off the wing several times. I can get a sufficiently long (barely) bolt in there to attach it. +++ #9501 From: sonny cilley Subject: Re: Digest Number 741 Hi guys, as I was sitting here reading all of the ideas you have offered to me for fixing a narrow pocket on the flap. I thought that this aircraft I'm building is not perfect ,in fact I don't want a perfect one, because I wouldn't dare fly it fear of scratching it. I want something that works. anyway, I have only got this one flap hinge pocket a little narrow and 5 more to go, so out are the joggles, holes and in is the thought of just splaying the nose ribs 1/8 " each and I'm back to the demension it calls for . done. thanks for all the info , that is why I read the digest .. +++ #9515 From: Budd Davisson Subject: Re: Digest Number 737 One of the solutions that one of us has to ask The Bob about is cutting a 5/8" (a guess) lightening hole in one of the ribs that form the hinge cut out. A lot of airplanes have that and you use a pair of needle nose pliers to hold the bolt and back it into the hole to get enough clearance. Then you can get almost any length bolt in there. I can't see a problem with the hole and Ikeep forgetting to ask Bob about it. It wouldn't need to be flanged. +++ #9521 From: sonny cilley Subject: Re: Digest Number 744 Hi guys, if the spacing of the flap hinge pocket is even a pain to get the bolts in at the demensions as drawn, what would be the hurt to widen the pocket out to 3" or 3 1/2" . I know that screwing with this is really up to Bob and people alot more knowledgeable than I. I ordered some new .063 plate stock friday so that I can end up with the pockets being the correct 2 3/4" spacing. . can't wait to get the flaps done so I can start a wing. +++ #9526 From: Russ and Penny Erb Subject: RE: Digest Number 744 In a statement highly uncharacteristic of me, if I was building the flaps and ailerons, I would widen the hinge pockets slightly. 1/4 to 1/2 inch would make a big difference. +++ #10590 From: Budd Davisson Subject: Re:flap reflex Why didn't any one comment on the note in Merle Hargraves description of his BH flights where he mentions he reflexed the flaps five degrees and got TEN KNOTS (!) more speed. That's significant and more than I anticipated when I suggested it. Think about that kind of free-speed benefit for a 540 powered airplane. Yeeehah! +++ #10604 From: "Bruce A. Frank" Subject: Re: Re:flap reflex In this context it means raising the flaps above their normal "up" position(in line with the wing). The rule of thumb has been that raising the flap so that went 7 degrees above the wing in the reflexed position. This reduces drag and increases speed. Maule has done this and many people rigged their Piper PA22s that way, finding the same benefit, until Piper said that the mechanism was not designed to support reflexed flaps. There has been experimentation with reflexing both the flaps and ailerons at cruise, but I don not know the results of those experiments. +++ #10605 From: Budd Davisson Subject: Re: Re:flap reflex Guess you came in after that thread, Jimmy, While flying the 540 powered BH, I saw that at a cruise speed of about 155 (23", 2300 rpm) the nose of the wing was noticeably down because it was a high lift airfoil being pushed so fast that to maintain level flight it had to assume a nose down position. This is a very high drag situation. One solution that was suggested was to rotate the flaps up, or reflex them, a few degrees to lower the coefficient of lift of part of the wing. This would let the nose come up to a more level position and lower the drag considerably. Maule does that already. I'm surprised, but delighted, to find it works even better for the BH, which will make the normal 540 powered BH a solid 165 mph not counting any aerodynamic clean-ups. 170 mph cruise at 65% doesn't appear to be out of the question, without compromising the low speed capabilities. Yeehah! +++ #10606 From: Russ and Penny Erb Subject: RE: Re:flap reflex budd hit the salient points, but why flap reflexing works may not have jumped out at you. Let me try to summarize. In this scenario, it does two things: 1. Increases the wing angle of attack so that the airfoil is working closer to its design lift coefficient where it will produce the least drag 2. It aligns the fuselage with the airstream so it produces the minimum drag (otherwise it is flying with the nose too low, thus producing more drag). You've got to be impressed when the only significant changes to the Bearhawk design since 1995 may be the addition of a cargo door and flap reflex. Most everything else is still like it was when originally released. +++ #10625 From: "Pat Fagan" pfflyerz@c... Subject: Re: Re:flap reflex No one has yet answered the question of HOW do you reflex the flaps. Our flap control is designed to pull the flaps down. Won't you also need a way to pull the flaps up, or will spring tension be enough to hold the flaps reflexed into the airstream? +++ #10626 From: "Jim Lathrop" Subject: Re: Re:flap reflex I asked The Bob about this at MERFI a couple of years ago. He of course pointed out he obvious. The weight of the plane will hold them up. All we have to do is stop them at the desired angle and possibly add a stop to the flap handle that will keep them locked at the normal full up and un-reflexed position. +++ #10628 From: Russ and Penny Erb Subject: RE: Re:flap reflex The theory is that the aerodynamic lift will keep the flaps up. To get the flaps to move up, I made my pushrod short enough that I can screw the rod end bearing in to shorten the pushrod. You'll probably also need to adjust the notches at the flap handle as well. We've said before the only reason for the springs is to hold the flaps up on the ground. In flight air loads will raise the flaps. Of course, when reflexing the flaps, the air loads will only lift the flap to a certain point where the air would start pushing it down again, but I think that point will be above the angle we need to reflex to. This is not an issue I would worry about on the first flight. It can wait until later. +++ #10643 From: "Pat Fagan" pfflyerz@c... Subject: Re: Re:flap reflex > I asked The Bob about this at MERFI a couple of years ago. He of > course pointed out he obvious. The weight of the plane will hold them > up. That is great news. I had already experimented with the idea when I first hung the wings on the fuselage. After hooking up the flaps as called for in the plans I set the pushrod to give 0 flaps in the second notch. Lowering the handle to the first notch then allowed for about 5 degrees of reflex. You lose out on the full flap extension allowed, but I believe Bob has said he doesn't use full flaps anyway, just puts them all the way down on the ground to wow the lookers. An added bonus to having 0 flap in the second notch is it alleviates the problem of the handle being too far away to reach when you are trying to apply flaps in the pattern. +++ #10655 From: "Corky Scott" charles.k.scott@d... Subject: Re: Digest Number 841 > No one has yet answered the question of HOW do you reflex the flaps. > Our flap control is designed to pull the flaps down. I can only answer in the general context of how the Christavia would work this, since I'm not building a Bearhawk. But the information may be of interest. To reflex the flaps, that is, to have them rest at an angle that has the trailing edge of the flaps higher than the line that goes from the leading edge straight through the trailing edge that normally would be the trailing edge of the wing, you have to allow the up stop to let them rest at the 5 or 7 degrees above zero. To do that, you just adjust the flap up stop to that value and presto, the flaps are reflexed at all times. In the Christavia, the plans call for a fixed upstop for the flaps, but I didn't like that idea. The stop was supposed to be weled to the hinge so that once it was done, there was no changing it. Instead, I cut out a section of the hinge, and welded in a threaded barrel that allowed me to use bolt as the upstop. I can now adjust the stop to any position I want the flaps to be when they are retracted. I'll probaly leave them at 0 degrees for the first test flights, then try reflexing by adjusting the upstop as necessary and stop where I get best cruise. Having the adjustable upstops also will allow for adjustment of a heavy wing, if necessary. +++ #10810 From: sonny cilley Subject: Re: Digest Number 857 Hi guys, I have an insignificant question ,but still one. when you pop riveted the nose skins on your flaps. did you use flush rivets or just headed ones. my left flap is all clecoed and dimpled, I just haven't a way yet of dimpleing the nose skins of the flaps. my progress is all of the wing parts are made except the steel parts, ailerons are hanging on my office wall and the left flap is locked in the jig and will start riveting tonight. +++ #10811 From: Russ and Penny Erb Subject: RE: Digest Number 857 Yes, I used flush rivets. I don't recommend button head rivets there because there can be very little clearance between the flap and wing in some positions. Get yourself a way to dimple the skins. My technique was to find an RV builder who was done with his Avery deep-throat dimpler. He let me borrow it. +++ #10821 From: "Collin Campbell" Subject: rivets in flaps > ...when you pop riveted the nose skins on your flaps. did you use > flush rivets or just headed ones. I used 3/32" dome head rivets in this area. They don't protrude much, the fabric covers them nicely, and there is plenty of clearance between the wing. Of course the flush rivets will work also, just more work. +++ #10852 From: sonny cilley Subject: Re: Digest Number 859 > I used 3/32" dome head rivets in this area. I went ahead and borrowed a deep throated dimpler/riveter from my friend who does RV's and it did a great job on the nose skins, it was a little extra work to dimple the skins ,but it didn't take very long and I don't have to worry about any clearance problems. I was riveting the 3/32 426's tonight and because I'm cutting the rivets to length ,it leaves a not so square end on it and using the squeezer alot of them tended to roll one way or the other and some even cracked. it was starting to get under my collar a little so I quit for the night. I think the rivets have case hardend so tomorrow I plan on sticking them in the oven and then keep them in the freezer like I do the others . so tomorrow evening it looks like I'll be drilling out the bad rivets and get into the replaceing mode.,well enough for now , Sonny # 234 +++ #10861 From: "Pat Fagan" pfflyerz@c... Subject: Re: flap nose skins I too used flush rivets. From my experience, you could get away with useing round rivets, there is enough clearance. You would still have to use flush rivets around the hinge cutouts if you plan to use cover plates over them, so might as well flush the whole thing. Just got home from the drive to OSH, next year I'll fly. >>> 20may03 #11298-18250 +++ #12032 From: "Collin Campbell" Subject: missing lightening holes > I was just perusing the latest Bear-Tracks newsletter and noticed > that in the pictures of Collin Campbell's #370, that some of the > lightening holes in the flap and aileron ribs have been omitted. > Since I think he is a member of this list, I was just curious what > the reason for that might be. > I like the rear window treatment, it is about what I am planning for > mine. (the color scheme is coming along but slower than > anticipated). Del, the reason I left out the smaller lightening holes was that I just didn't think that much was to be gained by the extra effort. I did much the same for the lightening holes in the fuselage door sills, etc. I drilled the larger holes but left off the smaller ones. Even at that it was a LOT of work for such a small weight reduction. Someone mentioned to me that even Bob said that if he had to do it over, he wouldn't go to as much trouble as he did--drilling all those holes. But that is a choice everyone will have to make for themselves I guess. I am a firm believer in keeping things light, but one can get too carried away I think. Collin Campbell +++ #12506 From: "Dan Shilling" Subject: [Bearhawk] Drawing 12, Bushing I am a little confused about the bushing shown in the upper left corner of drawing #12, (1/4" OD X 3/16" ID). It doesn't say what it is made of other than the note in the legend saying 4130. If it is other, please advise. Also, if it is 4130, he doesn't say wall thickness, just what it is supposed to end up as. I am just about done with the wing steel parts while I wait on some supplies. I see molten puddles when I close my eyes at night. Thanks, Dan Shilling +++ #12524 From: Russ and Penny Erb Subject: RE: [Bearhawk] Drawing 12, Bushing If I remember correctly (that was a long time ago)... As drawn, the thickness of the bushing is .032 (not .063 as reported earlier--forgot to divide by 2 for 2 sides). I think Pat found some bushings to use, but they were too short so he had to use multiple pieces in each application. My approach was to replace the 3/8x.058 tube with a 7/16x.058 tube. That allowed me to make the bushing out of 5/16x.058 tube. Remember the point of the bushing is to provide a compression member to tighten the bolt onto, yet leave the joint free to rotate. Friction is not as big of a problem in the flap circuit, so fancy bronze bushings are not required. Russ Erb +++ #12563 From: "Dan Shilling" Subject: Pop Rivet Question I'm getting ready to finish up the flaps and the plans say to use pop rivets on the nose and trailing edges. I saw the note in the Beartracks about replacing the stainless steal ones with aluminum because of availability. My question is, are we talking about just plain old hardeware store aluminum pop rivets, or should they be the Cherry Max solid core rivets? Thanks for all the help guys. Dan Shilling +++ #12570 From: Russ and Penny Erb Subject: RE: Pop Rivet Question c. None of the above Under no conditions should you use hardware store pop rivets for any structural application. I'm not sure I would use them to attach the passenger warning placard to the instrument panel. Here's what I used: For the leading edge (aluminum rivets): Cherry N rivets BSC-43 For the trailing edge (stainless rivets): Cherry N rivets CCC-42 Find both on page 96 of the 2002-2003 Spruce catalog. Of course, Cherry Max rivets would be acceptable, but if you really want to spend that much money, buy the rivets above and send me the difference...8^) (The intent of Cherry Max rivets is to replace solid rivets where it is impractical (or impracticable?) to drive a rivet) Russ Erb +++ $Id: 2.1.6-Wing-Flap,v 1.9 2003/05/21 15:01:03 bentonh Exp $