+++ #13 Subject: Aileron Pocket Rib Locations From: Russ Erb This message supersedes my message of 12/30/97 "They just don't line up!", assuming any of you remember back that far. The issue at hand is how the aileron pocket ribs are attached to the rear spar. There is precious little (pert near none) information on the plans about the placement of these parts. Mike Meador's wing picture book helps a little, but doesn't show the whole story, at least not in a way that is immediately obvious. Now that I've been through the process of attaching the attach angles for these ribs, I can give a better report of my best interpretation from looking at the plans, drawing the plans in CADD, studying Mike's book, and copious head-scratching. You're free to disagree with me, but this is my best guess. We'll try to do this in a textual medium--a graphical medium might be easier, but such is not readily available to everyone on the list. To start, let's define some terms as I'll use them in this message. Inboard - toward the root of the wing Outboard - toward the tip of the wing Attach angle flange - the portion of the attach angle which is perpindicular to the spar (points forwards or backwards relative to the airplane Rib flange - The part that is bent over to rivet to the wing skins. The direction the flange "points" is from the web of the rib (the vertical part) toward the edge of the flange "Normal" attach angle attachment - the attach angle attaches to the rib on the same side of the web as the flanges are. If the rib was seen as a "U" in cross section, the attach angle is "inside" the "U." This is the way all of the nose ribs and center ribs are attached. The center of the rib flanges are on roughly the same plane as the rivets holding the attach angle to the spar. "Backward" attach angle attachment - the attach angle attaches to the rib on the opposite side of the web from the flanges. The center of the rib flanges are about 1/2" away from the rivets holding the attach angle to the spar. Is - if you don't know the definition of is, ask the President Tip Ribs This is a little off the subject, but it is related. The tip rib is attached to the main spar with one (not two) attach angle on the rear side of the spar, and to the rear spar with one (not two) attach angle on the rear side of the spar Aileron Pocket Ribs We'll label the aileron pocket ribs from inboard to outboard as 1 to 8. For numbers on the center ribs, see drawing #2. The idea is to line up the pocket ribs as close as possible to the ribs in the aileron. Rib 1. This one is the biggest problem, so we'll talk about it first. The attach angle is attached at the rivet location 67" inboard of the spar tip. The attach angle flange is outboard of the rivets attaching it to the spar. The rib is attached to this angle "backward" with the rib flanges pointing outboard. To best line up the rib with the aileron, the side of the attach angle that attaches to the spar was made 0.1" wider (0.6" wide instead of 0.5"). This shifts the rib 0.1" farther outboard. The attach angle is only attached to the spar at two places, at the spar cap rivets. The loads are small, so this shouldn't be a problem. Rib 2. The attach angle is attached at same location as center rib 9. The attach angle flange is inboard of the rivets attaching it to the spar. The rib is attached to this angle "normal" with the rib flanges pointing outboard. Rib 3. The attach angle is attached at the rivet location 53-5/8" inboard of the spar tip. The attach angle flange is inboard of the rivets attaching it to the spar. The rib is attached to this angle "backward" with the rib flanges pointing inboard. The attach angle is only attached to the spar at two places, at the spar cap rivets. Rib 4. The attach angle is attached at same location as center rib 10. The attach angle flange is inboard of the rivets attaching it to the spar. The rib is attached to this angle "normal" with the rib flanges pointing outboard. Rib 5. The attach angle is attached at same location as center rib 11. The attach angle flange is inboard of the rivets attaching it to the spar. The rib is attached to this angle "normal" with the rib flanges pointing outboard. Rib 6. The attach angle is attached at same location as center rib 12. The attach angle flange is inboard of the rivets attaching it to the spar. The rib is attached to this angle "normal" with the rib flanges pointing outboard. Rib 7. The attach angle is attached at the rivet location 10-1/2" inboard of the spar tip. The attach angle flange is inboard of the rivets attaching it to the spar. The rib is attached to this angle "backward" with the rib flanges pointing inboard. The attach angle is only attached to the spar at two places, at the spar cap rivets. Rib 8. This rib attaches to the same attach angle as the tip rib. According to at least one picture in Mike's book, the tip rib is attached to the outboard side of the attach angle flange, and the pocket rib is attached to the inboard side of the attach angle flange. This will probably require shortening the pocket rib web a little bit to make room for the bend radius. More updates as I progress. +++ #137 Subject: wing skinning From: Pat Fagan (pfflyer-) Wow, it took me a long time to get back to together with you guys. At least I have been productive in the interim. I have my left wing finished and am ready to rivet the right one together. I just wanted to relay to you where I made an error so that no one repeats it. In trying to determine where to put the last aileron pocket rib I tried measuring from the plans, then mounted the rib and cut the wing skin to match. When I finished the wing and began to assemble the aileron I discovered that putting the hinges where the plans called for them would cause the aileron to extend beyond the edge of the inboard wing skin by about 1/8 inch. I had to move my hinge attach holes inboard by that much to make the aileron fit the wing. Bob designed it so the three gaps between control surfaces are pretty even, but they will be a little off on my left wing. Anyway, to ensure that doesn't happen again, I clamped the hinges to the flap and aileron spar, then placed them in the brackets on the rear spar before doing any drilling or cutting. That way you can verify that your rear spar hinge brackets are where your flap/aileron spars are expecting them to be, and you can adjust accordingly. It also allows you to get your gaps even, and now I know exactly where to put the final aileron pocket rib. Hope that helps. +++ #144 Subject: Bending Dies From: Pat Fagan As you saw in the newsletter, I was having trouble figuring out how to hold the flap and aileron spars during assembly. I finally cut some blocks of wood on my radial arm saw with a 1.5 degree angle on the vertical surface. I clamped these blocks to my flat table, then clamped the spar to the blocks. This held the spars at the proper angle so that everything else simply had to be flat to the surface of the table. I used the spar for the other aileron/flap as a straight edge to insure all tail ribs were the same length. This worked very well, and I didn't have to partially rivet the nose skins on for alignment like Bob mentioned. +++ #145 Subject: Finally an Aileron answer From: Russ Erb > Howdy: Ive been going at the building of the ailerons pretty hard > latley and have the 1st one ready for riveting ribs to spar bit I > have a couple questions and obsevations. 1/It would appear that the > .020 nose skins are in 3 peices- center from hinge area to hinge > area -inboard and outboard.That leaves the area over the spar flange > at the hinge location .020 lower than the adjoining area. For those > of you who have built your aierons what did you do about this? Did > you use a small peice of .020 under the gussets or will the gussets > fit O.K. without that? A study of Mike Meador's picture book shows that Bob did not bother to fill the gap. The gussets bend down slightly in between the nose skins. Less weight, and virtually unnoticeable after covering. +++ #148 Subject: Finally an Aileron answer From: Pat Fagan I went ahead and bent my flap and aileron nose skins as one big piece. I drilled the solid piece to the ribs, then cut out the holes for the hinges. This left the small strips above and below the hinge holes intact, which seemed to make for a very solid unit. It required a little caution to re-clecoe the skin to the ribs after cutting out the hinge holes, as it wasn't as strong where the 5/16 inch flange had been unbent to clear the ribs. +++ #149 Subject: Aileron Balance Tube Notes From: Russ Erb The following is a discussion I had with a good friend of mine who is building a Pulsar. Thought y'all might benefit from the additional info. >From me: In order to avoid having to melt lead (a good safety move), one of my newsletters the following method for making balance weights: "Mix the lead shot with epoxy or a slow setting polyester resin and pour the mix into the [aluminum] tube." Can you recommend an epoxy that will bond to lead and aluminum? >From him: The way you discribed the process is exactly the way that it is done in the Pulsar manual. I would use Hexcel 2315 but you could use just about anything, just make sure that the aluminum is roughed up, 80 grit and very clean. It will never come loose. >From me: To ask the silly question, how do you rough up the INSIDE of a 3/4" aluminum tube? >From him: Ah, so you think it hasn't been done? Well let me tell you how..... Get a 1/4 inch rod, preferably longer than the depth you need to rough up. Take a hack saw and make a slit through the center line at one end about 1 inch deep. Now cut some 80 grit sandpaper 1 inch X 4 inches. Slide the sandpaper into the cut on the rod so that 1/2 inch sticks out on one side and the other 3 1/4 inches sticks out the other side. Chuck the other end of the rod in your drill motor and wrap the sand paper around the rod, push it into the tube and let her fly... It will become evident which side of the sandpaper is short and which is long as soon as you try it, it would take too long to discribe in words. Happy sanding... +++ #306 Subject: Well, krap! From: Russ Erb I just had one of those situations that we all probably face on occasion that may not be painful, but is at least incredibly annoying! I have two very nice flaps completed now. I even took one to an EAA Chapter meeting last night and received many compliments. This part is most kewl. Feeling bouyed by this success, I went out to continue work on the first aileron tonight. The ribs are on the spar as is the aluminum skin and corner gussets. I had just finished marking the trailing edge and was about ready to put it in position when I looked to see how straight it was. There was a slight bend in it, so I tried to straighten it. In doing so, I buckled one side of the trailing edge (not hard to do). Feeling somewhat stupid at this point, I attempted to undo my gross buffoonery. In doing so, where it had buckled went CRACK! for about 1/4 inch. Now it's one thing to stop drill a crack on a part that is already part of an airplane, but there's no excuse for doing to a part that hasn't even been fitted yet. Therefore, that trailing edge has been relegated to the EAA Chapter supply of unserviceable parts, suitable for allowing the great unwashed public to handle at airshows and fly-ins. The worst part is not feeling stupid for the gross buffoonery that caused the problem. The worst part is realizing that it will now take another 8 hours or more to make a new part to replace it. And that's assuming I still have material on hand. Even so, quality is important. I don't claim to be trying to build a Grand Champion, but I'm shooting for something well above a two-bagger*, something that I'll have confidence in to fly myself and anyone else. Make the tough decision. Throw out any defective parts and make replacements. +++ #401 Subject: First Aileron Riveted From: Russ Erb I just finished riveting my first aileron. For those who care, the weight of the aileron (without balance weight or hinges) was 5.9 pounds. Has anyone balanced an aileron yet? How heavy was your balance weight? I know each one will be different, but it would be nice to know about how much I should expect. The ribs of the second aileron are riveted to the spar, and the rest of it is ready to cleco together and rivet. After that, I'll sandblast and prime the wing steel parts, then start assembling a wing. +++ #409 Subject: First Aileron Riveted From: PAT FAGAN I have experimented with balancing the aileron. I turned two aluminum plugs for either end of the balance tube that I planned to rivet in place. That way, if I needed to add more weight after fabric covering I could. Turns out that to balance my aileron by guesstimating the fabric weight requires that the tube be almost completely filled with shot, with no room left for my plugs. So much for that idea. I haven't weighed it, but the whole thing is pretty heavy. For Russ, I bought a 25 pound bag of lead shot at Burbank Metal Supply, should be enough for both our ailerons if you want to split it. +++ #410 Subject: Re: Aileron Balance From: bearhwk27- With respect to the issue of balance on the ailerons, I have no reference material available to me right now but something tells me that "balancing " is the act. The correct amount of lead should yield a control surface that hangs "nose " heavy by 15 to 25% when covered. Just in "balance" level is in sufficient for creating a large enough margin to ensure flutter elimination. I will try to get a better reading on this in a few days. Mike, Bob, can you shed any light? +++ #411 Subject: Re: Aileron Balance From: Float-by Shooter What does anybody think of just filling the entire tube with lead, and then drilling out whatever is needed to obtain the desired balance after covering? A small patch to cover the drilled end of the tube shouldn't change the balance appreciably (and would be on the right end to be adding weight anyway). +++ #531 Subject: 2nd airplane From: gdanfor- I am glad to be a member of the "egroup" and thought I would let the group know that I am working on a Bearhawk. Have finished most of the ribs and have finished the flaps and one Aileron. I noted looking at the photos of the Bearhawks under const that most are puting the lightening holes in the flap and aileron ribs. Would suggest to the group to leave the end flap and aileron ribs solid. In this part of the country (Kansas/Missouri) the mud wasps can add pounds in a hurry if they can get in. I would leave the ends solid to facilitate the covering and keep out the wasps. This is my second homebuilt the first was a Hatz CB-1 that if you are interested has its own web site at http:\\members.tripod.com\~gdanford/index.html The site is hard to hit and the html address is case sensitive. +++ #532 Subject: Re: 2nd airplane From: Float-by Shooter > photos of the Bearhawks under const that most are puting the > lightening holes in the flap and aileron ribs. Would suggest to the > group to leave the end flap and aileron ribs solid. In this part of > the country (Kansas/Missouri) the mud wasps can add pounds in a hurry > if they can get in. I would leave the ends solid Since the flaps and ailerons are fabric covered, wouldn't you just cover the lightening holes on the ends with fabric? Are you worried about the mud wasps getting into the wings through the exposed lightening holes in the rear spar, in front of the flaps? +++ #865 Subject: aileron hinge point From: robert gaddy Could an Aero guy help out this poor Mechanical guy? While studying the wing plans, I noted on Drawing 10, in the "Aileron and Hinge" layout, a small X between the letters of "D" and "B" on the lower surface of the aileron. I think that this is the center of curviture of the aileron nose rib forward skin, as well as the pocket rib aft skin. These two skins form a slot between the wing and the aileron. Since the aileron pivot point in located above this "X", the gap between the aileron and the wing will close up when the aileron is deflected (trailing edge)downward. Is this done on purpose? Could mud or ice cause a problem when the gap closes? If the pilot point were at the "X", the gap would remain constant with aileron deflection. I don't see that the ailerons are of the frissne (spelling?) type that adds drag on the upward deflecting aileron to imporve turn coordination. I also don't see any reason why the pilot couldn't be moved to the "X", just below the wing lower surface, with a redesigned aileron bracket. I note also in the Davisson aritcle that the ailerons were judged a bit "heavy". Any comments? +++ #870 Subject: Re: aileron hinge point From: budd davisson > I note also in the Davisson aritcle that the ailerons were judged a > bit "heavy". Any comments? Re: "heavy" I said the ailerons were heavy for my taste, but remember I spend 30 hours a month running around the pattern with students in my Pitts so I'm aileron pressure-sensitive. They are about the same as a Cessna. However, Bob has moved the hinge point back slightly on his latest version of the ailerons which should reduce the pressures greatly. When I finally get a go at the 260 version, we'll all find out. About the closing up of the gap when the aileron displaces: That's part of the Curtis Pitts "Super Stinker technology" where the ailerons gap seal themselves as they are deflected which greatly increases effectiveness. On the true Super Stinker type aileron, they are symettrical (16% thicker than the wing at that point so the leaded edges stick up and down out of the wing in neutral) which keeps airflow attached much better. If Bob has offcentered the hinge point in such a way it closes the gap, he has captured the best part of those types of ailerons and it should be very noticable in improved roll rate. If Sport Aviation decides not to have me do a pirep on it, I'll fly the airplane and put it on my website as well as posting it here. +++ #876 Subject: Re: aileron hinge point From: zippydog- Budd, welcome to the group with your Desert Hawk, it should be a crowd pleaser. Thank you for your comments about the aileron feel and design. I feel much more comfortable with the design now. You mentioned a change in aileron pivot point. Do you know if this change has been incorporated into the plans yet? I was under the impression that Proto II was built "as plans" to verify the plans. I may be jumping the gun a bit, but when ready to cut metal, I would like to be building the best version. +++ #879 Subject: aileron hinge point From: Russ Erb > Could an Aero guy help out this poor Mechanical guy? While studying > the wing plans, I noted on Drawing 10, in the "Aileron and Hinge" > layout, a small X between the letters of "D" and "B" on the lower > surface of the aileron. I think that this is the center of curviture > of the aileron nose rib forward skin, as well as the pocket rib aft > skin. These two skins form a slot between the wing and the aileron. I interpreted that "X" as the center of curvature. > Since the aileron pivot point in located above this "X", the gap > between the aileron and the wing will close up when the aileron is > deflected (trailing edge)downward. Is this done on purpose? Budd covered the closing gap concept (it was new to me--thanks Budd). The ailerons are of the Frise type. Look at what happens when the aileron is deflected trailing edge up. The nose of the aileron sticks out below the wing--this is what causes the extra drag to reduce adverse yaw. > I note also in the Davisson aritcle that the ailerons were judged a > bit "heavy". Any comments? As Budd said, he is used to Pitts controls which are very light, which is desireable for an aerobatic airplane. For cruising with low pilot workload, you want heavier forces. That way you're less likely to bump the controls and upset the airplane. I've never understood RV builders who talk like very low control forces are a sign of "goodness". The Mil Spec on flying qualities says just the opposite where cruise is the primary mission. Many of those RV builders put in a wing leveler for cruise to fight the tendency to roll off one way or the other constantly. As a Pitts driver what it's like to fly cross country--I suspect he'll say it's work. +++ #880 Subject: Re: aileron hinge point From: budd davisson Mike could verify this, but I seem to remember Bob telling me he changed the pivot point shortly after I flew the airplane, which was around four or five years ago. He went back another couple percent which would make a huge difference. +++ #881 Subject: Re: ailerons From: budd davisson > Many of those RV builders put in a wing leveler for cruise to fight > the tendency to roll off one way or the other constantly. As a Pitts > driver what it's like to fly cross country--I suspect he'll say it's > work. First, nothing in a Pitts is work. Not even the landings. I'm a handling freak and of the production airplanes like the Beechcraft approach to ailerons best: reasonable breakout force into a fairly flat, smooth pressure gradient (they don't heavy up much as deflected). The Mooney is an example of what I don't like: heavy breakout forces, steep force gradient. The original 'Hawk's were somehwere around Cessna with a hint of Mooney. Of one of the most important things you can do in getting good aileron feel is eliminating as much system friction as possible. That means lining up all the fairleads with the cables, ball bearing pulleys and either bearings or bushings in the aileron hinges. Slick is the name of the game. Even with all of the pushrods and hinges in a four aileron Pitts, with it sitting on the ground, you can pull the stick to the side and when you let go, it smoothly goes back to center and rocks just a little. No friction whatsoever. +++ #3634 From: Russ Erb Subject: Glad to be of service... Once again my gross buffoonery has shown up in Bear-Tracks. Well, at least I inspired an entry. You may recall a couple of months ago that I mentioned in this forum that I had noticed that I put 6 of the 8 gussets on the ailerons in the wrong locations. The point was that some were 0.032 thick and others were 0.025 thick. Well, if you look on page 4 of the October 2000 Bear-Tracks, you'll see an admonition that effectively says don't do what I did. Of course, Mike was nice enough not to drag my own dirty laundry through the Bearhawk community. He knows that that is my job! +++ #3696 From: sonny cilley Subject: Re: [Bearhawk] Digest Number 207 hello, I have a small ? . I finally am putting the ailerons together and the plans call for 3/32 SS pop rivets, is there any reason that I have to buy the expensive cherrymax or is it alright to just get regular SS pop rivets and also is there any reason that I couldn't get a little bigger rivet than 3/32. they are such a pain to work with.it sure is nice to see some structure after 3 1/2 yrs of just building parts, this is getting to be too much fun. thanks, Sonny # 234 +++ #3702 From: Russ Erb Subject: Re: [Bearhawk] Digest Number 207 From the July 1999 Bear-Tracks: "Engineering Notice: Reference plans number 395 and below, Drawings #9 and #10. The 3/32" stainless steel pull rivets holding the nose skins to the nose ribs have been changed to 1/8" aluminum pull rivets. The cost and availability of 3/32" S.S. rivets has become a problem. If you have already assembled the ailerons and flaps with the S.S. you can leave them in, they do a good job. " (Easily found on the Bearhawk CD) +++ #3706 From: sonny cilley Subject: Re: [Bearhawk] Digest Number 208 thanks Russ, the 1/8" SS pop rivets are easyer to work with and easyer to find , at least up here in Vt. I should have both ailerons together by the end of the month. everyone is talking about times to build, does it matter, it is still one piece at a time and it will get done when it gets done.thanks, Sonny #234 +++ #3714 From: Russ Erb Subject: Re: [Bearhawk] Digest Number 208 > thanks Russ, the 1/8" SS pop rivets are easyer to work with and > easyer to find , at least up here in Vt. I should have both ailerons > together by the end of the month. everyone is talking about times to > build, does it matter ,it is still one piece at a time and it will get > done when it gets done. Go back and re-read that message. Bob said 1/8" ALUMINUM blind rivets were suitable. I think I used Cherry Q rivets. Don't use those you get at the hardware store. Of course, if you'd rather use stainless that should be fine too. +++ #3733 rom: sonny cilley Subject: Re: [Bearhawk] Digest Number 209 Russ thanks again . I didn't click on the word aluminum in your e-mail.Aluminum rivets sound more like it than Stainless,and I believe the price will be better. it did made me wonder whether dis simalar metals would be a problem. +++ #3738 From: Russ Erb Subject: Re: [Bearhawk] Digest Number 209 > Russ thanks again . I didn't click on the word aluminum in your > e-mail.Aluminum rivets sound more like it than Stainless,and I > believe the price will be better. it did made me wonder whether dis > simalar metals would be a problem. Now that we have that straightened out, notice that the rivets at the trailing edge are 1/8" stainless. I'm guessing Bob is specifying stainless in this location for higher strength, especially since there aren't very many rivets in that vicinity. +++ #5114 From: Russ Erb Subject: Balancing Ailerons It is important that ailerons be balanced for at least two reasons. One is a possible effect on aircraft handling qualities. The other is to guard against flutter or "aileron buzz". One of the challenging things about the design of the Bearhawk ailerons is that you have to balance them before covering, and the covering affects the balance. Therefore, we must estimate weight and c.g. location of the covering. The system I will be using is reported to weigh 0.85 oz/sq ft. Doing some analysis with the drawing (what some of you may consider excessive, but no where near as excessive as it could have been) I came up with an approximation that the weight of the fabric and coatings on one aileron will be one pound with a cg 10 inches aft of the leading edge of the aileron. To balance the aileron, I suspended it from an overhead beam upside down with fishing line through each hinge point. A piece of angle iron cut to weigh one pound was placed centered on a line 10 inches aft of the leading edge. I then stacked some square steel tubing I had available over the location of the counterbalance tube. For fine tuning, I used some AN970 washers. The necessary balance weight for a perfect balance on the first aileron was 5.275 lbs. Much to my surprise, the exact same amount was needed for the second aileron (I figured there'd be at least a little difference). According to the July 1996 Bear-Tracks, up to 10 percent overbalance is allowed. I'm not sure exactly how "overbalance" is defined, but my best guess is that "The Bob" meant the weight of the balance tube could be up to 110% of what was necessary for a perfect balance. That means my balance tube could weigh up to 5.8 lbs. A little calculating with the Bear-Tracks value for lead density (0.41 lbs per cubic inch) yields that the maximum amount of lead that could be placed in the balance tube is 6.01 lbs. Therefore, mine will be very close to full. I'm not too crazy about the idea of melting lead and pouring it down the tube. (Kevin Deutscher did this, and reported that he had to use a propane torch to warm the aluminum tube--otherwise the lead would solidify on the cool tube walls and block the tube before reaching the bottom of the tube.) I was going to follow the alternate method (April 99 Bear-Tracks) of mixing lead shot with epoxy. Bob claimed to need about 5 lbs per aileron, close to what my measurements show. I figured I'd do this on the cheap. I had some lead shot that was no longer needed at work. As a check, I poured the shot in the tube without the epoxy. The problem was that this shot is 00 buckshot (rather large) and left a lot of air space between the pellets. The resulting weight was only about 3.5 lbs. That won't do. Here's the new plan (with partial credit to Kevin): I picked up a bag of 8.5 bird shot, the smallest they had at the local hardware store. I will take a short piece of 3/4" wood dowel (maybe 3/4") sanded down to fit into the tube and use it to plug the end of the tube. I'll pour in a small amount of shot, and tamp it down using a 5/8 steel rod, much like loading a muzzle loader. Because the lead is soft, it should deform and press some of the air out. Pour in some more, then tamp again. Repeat until the tube is almost full. Don't tamp too hard or you may swell the tube, which then won't fit back in the aileron. If the tube gets too heavy, I'll drill out some of the lead. When it is the right weight, I'll fill the end with an appropriate epoxy. After that has cured, I'll drill out the wood plug and fill that end with epoxy. Remember that a small amount of lead will be drilled out to make way for the pop rivets that will hold the tube in place. That's what I have to say on the subject for now. More details after I actually do it. +++ #5117 From: Budd Davisson Subject: Re: balancing shot A note about shot and balancing: It might be worth the effort to call some of the shot gun reloading outfits and look for finer shot. There is some bird shot that must be down around No. 12 or finer that pours and packs like sand. Then, when pouring it you use a "drop tube" like we use in loading black powder cartridges. It's a tube the same size as the one you're pouring into with a funnel at the top end. As you pour it in, it gets some inertia going and packs itself really well without undue tamping. Using this small shot, you eliminate a huge amount of air space and can calibrate the wieght to a gnat's hienie. Let me know,if you can't find the shot (assuming youwant to go to the effort) and I'll make some phone calls. +++ #5124 From: Mark Deacon Mark_Deacon/MSP/Mesaba%Mesaba@M... Subject: Re: [Bearhawk] Balancing Ailerons I'm nowhere near balancing the control surfaces but have given it some thought. As for the ailerons, my thinking was to continue the holes used for the balance tube all the way out to one end of the assembly. Then after covering I would pass a long drill bit or a bit on the end of a drill extention thru the hole and drill out material till the correct balance is acheived. If a "cold" process is desired and small enough shot is not available you could use lead wool, looks just like steel wool and compacts down quite nicelly. We used this stuff to static balance individual propeller blades and it is available through most industrial supply houses, McMaster-Carr for one. For cheap weight to melt down I'm planning to get old wheel weights from a local garage. They usually have buckets of them around and are happy to get rid of em. For the elevators I'll clamp sheet steel to each side of the tubing and pour in place. Then during covering install an inspection cover reinforcement over the weight, cut out and drill to balance like the ailerons. +++ #5210 From: Russ and Penny Erb Subject: Insufficient Mass Has anyone successfully filled the aileron balance tube with sufficient lead by any method other than melting and pouring? I tried pouring in #8-1/2 shot and still got about 3.75 lbs (need about 5.5 lbs). I then tried Kevin Deutscher's suggestion to pour in a little, hammer it down, add some more, hammer, etc until full. Short of deforming the tube, I couldn't hammer it hard enough to really compress the shot, so the weight was no different (and the shot poured right back out). By my calculations, 42.8 per cent of the tube is filled with air. As much as I would rather not, I think I'm going to have to do the melt and pour, unless one of you has a better idea. I have determined that lead melts at 621 F and aluminum melts at 1220 F, so I should be able to melt it in an aluminum pan (which will never be used for any other purpose). Looking back at Bear-Tracks, it recommends a stainless steel pan. Mike Meador: The April 99 Bear-Tracks says that Bob used the epoxy/shot method on Proto II. Details please! Did the tube end up lighter? He said we'd need about 5 lbs of shot per tube, but I don't see how to get that much it... +++ #5211 From: Mark Deacon Mark_Deacon/MSP/Mesaba%Mesaba@M... Subject: Re: Insufficient Mass Back in the good old days when my employer, Mesaba Airlines,flew DeHavilland Dash-8s we in the engine/propeller shop had to static balance indavidual prp blades. We used lead wool, looks just like steel wool and we would tamp it into the spar bores to match a certified master. McMaster-Carr caries it at $12.50 for 5lbs in cat. #103. Now between our pounding and centrifugal force it took an 8000psi preassure blaster to remove the stuff so if your sold on a cold process this could be the ticket. I was planning on making the holes in the nose ribs all he way out to one end, filling the tube to over balance then removing material with a drill to bring the surface back to 100% or a little over. Any idea how much weight the elevators need? Hope this helps. +++ #5212 From: "DANFORD, GARY" Subject: RE: [Bearhawk] Insufficient Mass I had the same problem during my first try. I then heated the lead hotter, preheated the tube with the torch (not a lot) poured faster and it worked. I didn't weight it but the tube filled correctly and I left the end open to drill out excess if necessary. I also used the dog's Stainless Steel bowl to melt in. Of course I put it back when finished and wife wasn't too happy over my borrowing it but the dog wasn't the wiser. +++ #5213 From: Shelly Subject: Re: [Bearhawk] Insufficient Mass If the tube fills with lead, you're OK! But if you are worried that the lead will shake loose and shift the balance, then put a couple of pop arivets through the tube before you pour - problem solved. +++ #5215 From: Benton Holzwarth Subject: RE: Insufficient Mass From: "DANFORD, GARY" > > I also used the dog's Stainless Steel bowl to melt in. How about using a old tin can (which is really steel, afterall). Bend a pour spout into it before starting, heat with a Coleman stove (or isn't that hot enough?), and pick up with tongs. +++ #5216 From: Budd Davisson Subject: Re: [Bearhawk] Insufficient Mass I just checked and the smallest commonly available shot is no. 9 which isn't going to increase your filling capabilities much. It would be nice to find some 11 or 12 bird shot, but apparently that's not easy to come by. The lead wool someone mentioned sounds like the ticket, if you want to do it cold. If doing it hot,I think it was Kevin who mentioned warming the tube before pouring, which makes perfect sense, as the tube is a heat sink. +++ #5218 From: Ken Beanlands Subject: Re: [Bearhawk] Insufficient Mass We made lead ingot using a coleman stove and some cast iron pots. The cast iron will keep the lead in liquid form long enoug to pour it. Oh yeah, we got about half a ton of lead from the local garages in the form of wheel weights. A lot of garages have a tendancy to keep old weights in a bucket rather than tossing them out (who knows why). Yeah, thery are dirty and have a steel clip, but interestingly enough, that stuff all floats to the top where you can scrape it off with a piece of aluminum. Worked like a charm and didn't cost us a cent. Oh yeah, the reason for the lead was to form a keel for a sailboat that we never did build (20' Bluenose hull replica, sloop rigged that required 800 lbs of ballast) +++ #5219 From: Pierce Terry M Civ 412 TW/TSI Subject: RE: Insufficient Mass You might consider using a sandbox and a dowel. Make the sand lightly damp, not wet. Pound sand around 2 or three inches of dowel with on OD slightly less than the ID of the tube. This leaves a rough casting which will allow resin to move around the side of the slugs and lock them in place. Make enough of them to fill the length of the tube. Also, when I melted 12,000 lbs of wheel-weights for a sailboat keel, I found that using a piece of aluminum (or any metal for that matter) to form a chimney around the melting pot decreased melt times by a factor of 4 or 5. No kidding. Just take a flat piece, curve into a cylinder, and use a couple of metal screws or rivets to hold it in a cylindrical shape. You'll probably need to notch it for the pot handle. OF course, decreasing melt times for only 5 lbs might be a classic example of misdirected time and energy. +++ #5222 From: "Bill Cox" Subject: Re: [Bearhawk] Insufficient Mass I melted lead using a coffee can on a Coleman stove. I did not preheat the tubes and didn't have any problem getting them filled. I used 2 pair of vice grips and welding gauntlets to handle the hot lead. The bottom of the tube was plugged with a piece of pine whittled to fit. The bottom of the tube was pushed down in a 5 gallon bucket of dirt and the top was wired to a sawhorse. It's been a while but I believe the filled tubes weighed 5 LB, 7 oz. I cut holes in the outer rib leading edges to allow fine tuning of the balance after covering. Both tubes start to finish was about a 30 minute job. +++ #5223 From: "Donald Schindler" Subject: Re: [Bearhawk] Re: Insufficient Mass Russ, You can get lead wool at Home Depot or any good plumbing shop. I use it to balance Hamilton Standard props. You can hammer it to a near solid mass if you need to. +++ #5224 From: Tim Subject: Re: [Bearhawk] Re: Insufficient Mass You can also melt lead on the stove, keeping in mind VENTILATION. I've made Bullets this way and also several scuba weights in past years, as I have both molds. Some of my scuba weights did reach Mach, if ya catch me drift. Good Karma to use these, especially if you plan on FLOATS ;-) +++ #5227 From: Jim Ash Subject: Re: [Bearhawk] Insufficient Mass > I melted lead using a coffee can on a Coleman stove. I did not > preheat the tubes and didn't have any problem getting them > filled. I used 2 pair of vice This seems the most practical. One of the catches to this method is to pour it quickly, without stopping. If you pour it slowly, the tubing can 'chill' the lead on the way in and could plug the tubing, leaving gaps underneath. One of the foundry techniques is to heat the metal a good ways past melting point before pouring. This will give you some time to handle the metal and retard the mold from chilling it. One of the tests I use with aluminum is to quickly stick an old piece of steel bar stock into the pot and remove it, before pouring. It should come out clean. If the metal temperature is still too cold, it will come out with metal goobers stuck to it. If this rod can chill the melt, so can your mold. Although I've never tried it, this technique should also work with lead. Please heed Tim's warning about ventilation. Lead and zinc vapors are nasty stuff. Blood poisoning from lead vapors turns the skin a really cool shade of gray-green. Don't do this stuff indoors. The same zinc warning applies if you're trying to weld galvanized steel. Don't. +++ #5228 From: Shelly Subject: Re: [Bearhawk] Insufficient Mass > I melted lead using a coffee can on a Coleman stove. No big deal about heating the lead-- use your welding torch! +++ #5230 From: "Bruce A. Frank" Subject: Re: [Bearhawk] Insufficient Mass Well, zinc will make you sick as a dog, but it won't kill you. And it's gone from your system in a few hours. Lead on the other hand is persistent in the body, may lead to organ and brain damage and since the body cannot easily rid itself of lead you may require hospitalization and chelation therapy to remove it (an unpleasant process). +++ #5232 From: Russ and Penny Erb Subject: RE: [Bearhawk] Re: Insufficient Mass Thanx to everyone for all of your answers on the lead in the balance tubes. As a service to the Bearhawk community, I'm going to try the lead wool method suggested by Mark. I've ordered 15 lbs from McMaster-Carr. Note that the price is now $14.35 for 5 lbs. Del--Thanx for the offer, but don't ship your lead melter yet. I'll let you know if I need it. After I try smooshing the wool down in the tube, I'll report back to the group. I'd much rather have a method available for the Bearhawkers so we don't have to worry about lead poisoning. I figure I can use the shot I have when I get to the horizontal tail. Del may be onto something. A quick calculation shows that a 7/8" diameter 4130 steel rod would be heavy enough, but you would probably need another method to attach it than the blind rivets shown. Intriguing for those of you who haven't done your aileron ribs yet, as it's not that much bigger. +++ #5238 From: Kevin bearhwk272@a... Date: Tue Feb 27, 2001 7:09pm Subject: Re: [Bearhawk] Re: Insufficient Mass Hey If you are going to use a steel rod, just use plain old cold rolled. Same density as 4130, costs less and is stronger than lead. You will have to attach with other than a POP Rivet. For the corrosion nuts among us use 302 SS +++ #5239 From: Russ and Penny Erb Subject: RE: [Bearhawk] Re: Insufficient Mass I only mentioned 4130 because that was the first thing I found the density on. I agree that cold rolled would be adequate. +++ #5245 From: Russ and Penny Erb Subject: Lead Wool is the way to go! The Bearhawk Tipster of the Week Award goes to Mark Deacon (#188) this week for his suggestion of lead wool as material for filling the aileron balance tube. With this award comes the adulation of all of his fellow builders and eternal immortality on a future edition of the Bearhawk Reference CD. Sorry, cash awards are prohibited by law (and lack of a bank account). I had not thought of using lead wool for the simple reason that I had never heard of such a thing. As was suggested, I found some at Mcmaster-Carr (http://www.mcmaster.com), who sells the stuff in 5 lb bags for $14.35. Just go to the website and search for "lead wool". Took me right to it. Apparently the stuff is mostly used by plumbers in some cases to seal pipe joints. The lead wool is wrapped around the joint, then melted in with a torch. To install the stuff, I started with a 3/4" dowel, which I sanded down slightly so that it would fit into the aileron balance tube. This is a plug that should go into the end of the tube about 3/8" to 1/2". Cut it off flush with the end of the tube, because otherwise the ceaseless hammering to come will drive the plug into the tube. While it may be overkill, in the interest of safety, I wore rubber gloves (like examination gloves--use them while painting to keep your hands clean(er)) and a respirator. Lead is nasty stuff, so why take chances? Using snips, cut off a chunk of wool about 1/2" in diameter and about 1-1/2 to 2" long. Drop it down the tube. With the plugged end of the tube resting on a 2x4 on the floor, place a 5/8" diameter steel rod 36" long in the tube and drop it onto the lead wool. Lift up the rod and drop it several more times. The first time it will hardly bounce if at all. As the lead becomes a solid mass, the rod will bounce off it as though dropped on the floor. Pull the rod out. The result is a chunk of lead about 1/4" thick in the tube. Repeat above paragraph until the tube is full almost to the end. I managed to get the entire 5 pound block into the tube, with room for essentially no more. The result is a balance tube weighing 5.2 lbs. If you will recall, I was hoping for something between 5.275 and 5.8 lbs. I'll be happy with the result, because I don't see how to do any better. Even if I had poured molten lead, I think it would have only given me maybe and ounce or two more. After filling the tube with lead, drill out the wood plug. Be careful not to drill out the lead. I will fill the remaining 3/8" to 1/2" at each end of the tube with epoxy to seal in the lead. I highly recommend this method to anyone who has already made their aileron nose ribs and is thus locked into the 3/4" dimension. Hazards, such as handling hot lead, burns, fume inhalation, etc, are greatly reduced since this process does everything at room temperature. For those of you who haven't, I would recommend you consider (note the weasel wording) using a steel rod instead. It appears it would only need to be about 7/8" in diameter. To hold it in place, you would need a different method than blind rivets. An option would be to tap holes and use short machine screws to hold it in place. The weight would be the same, it shouldn't interfere with anything else in the aileron, and you don't have to mess with lead. +++ #5300 From: sonny cilley Subject: Re: [Bearhawk] Digest Number 338 I am in need of a little incite. Yesterday I bent up the flap spars and the trailing edges for the flap & ailerons. I am using 2024 t-3 . we made them as per plan and they cracked. the profile fit the one on the plans. should I not use t-3 stock and go to a softer material or am I just doing something wrong. the plans call for 1 3/4 " trailing edges, is there a reason that the 1 1/4" trailing edges sold by spruce and others won't work. +++ #5304 From: Russ and Penny Erb Subject: RE: [Bearhawk] Digest Number 338 Where did they crack? Are you using at least a 1/8" bend radius (fits a 1/4" drill bit)? I had no problems with the same material. +++ #5317 From: sonny cilley Subject: Re: [Bearhawk] Digest Number 339 When we bent the trailing edges we ended up matching the profile on the plans which call for a 3/32" radius. our bend fit nicely, most of the length of the trailing edge was fine except for about 2' of it which when we finished bending it to close over the ribs it stretched to much and cracked open. we experimented with a few pieces and they were fine before we did the real parts. I'll call Dillsburg today and order another sheet of .025 and go again. I'll also increase the bend radius and not try to fit the profile on the plans. +++ #5335 From: Russ and Penny Erb Subject: RE: [Bearhawk] Digest Number 339 I had forgotten that the plans said 3/32". I bent up everything on a brake that only has one bend radius--1/8". On the trailing edges, I couldn't form the full trailing edge angle on the brake. I bent it the rest of the way by hand and carefully with the seaming pliers. The end result matched the plans reasonably well. Don't get over zealous with the pliers or you will crack it. +++ #7150 Date: Sun, 12 Aug 2001 08:20:52 -0700 From: Russ and Penny Erb erbman@ Subject: RE: Digest Number 508 > To back some of you up a little in the building phase , in > balanceing the ailerons, is it physable to fill the balance > tube up with lead, build the ailerons, then balance them by > drilling out the un needed weight of lead. Yes, you could fill the tubes ahead of time and drill them later, although you'll find you pretty much need them completely full. Alternatively, I've suggested before (after doing mine) that a 7/8" steel rod will supply plenty of weight without the hassle/hazard of dealing with lead. Russ Erb >>> 2mar02 #7686-9153 +++ #7800 From: woodpret@s... Subject: aileron balance tubes. Hi guys, a couple weeks ago I poured the lead in the balance tubes, it was easy, easier than I thought it would be, didn't even get burned. afterward I was wondering if I had completely filled the tubes and got tapping on them and it didn't sound right,like there were hollow spots.so I emptied one tube and found that it hadn't filled all the way. I'm not sure what happened other than to think that the aluminum tube was a heat sink and cooled the lead enough so it didn't flow to the bottom. has anyone else had this problem. I am gonna redo both tubes soon. my idea is to strap the tubes to the wood stove and keep them hot and then pour the lead in. I ended up with about a foot of tube that didn't fill on the first attempt. the only other thought was that I didn't have the lead hot enough, I was starting to run out of gas for the burner. I'll let you know how it goes, Sonny #234 +++ #7804 From: Russ and Penny Erb Subject: RE: aileron balance tubes. That's most likely the problem. Someone else warned me that the tube needs to be heated with a propane torch prior to pouring so that the lead would make it to the bottom before cooling and blocking off the tube. I hammered lead wool in instead of pouring melted lead. When you're done, the tube should weigh about 5.5 to 6 pounds. If it's less than 5 pounds, you have voids in the lead. Russ Erb +++ #7805 From: bearhwk272@a... Subject: Re: aileron balance tubes. Yep, had the same problem the on the second tube. First came out perfect first time. Hotter lead works real well, my first load was a lot hotter because I got distracted with the bed time process for my daughter. The second batch I poured to cool. Third time, hotter lead, heated and insulated tube, piece of cake. Another tip, when pouring, slow down at the end and continue to pour a small stream to fill in for the shrinkage. Back at building cause is 85 Deg F now. Kevin Deutscher #272 +++ #7806 From: rsmith@a... Subject: Re: aileron balance tubes. I just did these and the elevator counterweights today. I wanted to do it outside and realized it could snow any day now. I warmed up the tubes with a torch and they filled very nicely. I used .032 4130 sheet on the elevators like Bill Johnson did. It extends 5 inches back toward the elevator strut from the forward point. I balanced the elevators by piling wheel weights at the proper location. I used a 14 oz piece of steel tube in the correct location to represent weight of the finished fabric. When I poured the lead into the counterweight area it came to 1/4" of the edge of the steel. I then fine tuned the balance by drilling a little back out. Worked really slick. Beats trying to cast them the right shape and then installing them with screws through the tubing. Rod Smith #246 +++ #7807 From: charles.k.scott@d... Subject: Re: Digest Number 568 Sonny, don't you weigh out the lead and then melt it? If there are voids in the tube but all the lead that needed to go in did in fact go in, what's the difference? Thanks, Corky Scott +++ #7811 From: sonny cilley Subject: Re: Digest Number 569 Corky, no I didn't weigh out the lead. I took wheel weights, threw them in the pot, melted the mess, skimmed off the weight clips and poured the lead in the tube, I figure that with the tube full of lead, then cut it to length to fit the aileron,it ought to be close. what can I say I'm left handed. anyway when cut to length I would weight it on a digital scale and go from there. think it'll work, I do., one of these days I have to stop on furnace rd. and see your project. Sonny #234 +++ #7813 From: charles.k.scott@d... Subject: Pouring lead for the counterbalanced ailerons I have a question. Why do you have to use an aluminum tube in which to pour the lead? Since the whole reason for the lead is to counter balance the aileron, why not use a steel tube and simply calculate the total weight; tube plus lead. Then you might not run into the problems of the aluminum cooling down so fast? I mean you aren't using the aluminum because of it's light weight, right? You WANT the weight, right? Corky (confused) Scott +++ #7816 From: charles.k.scott@d... Subject: Mearuring how much lead is needed > Corky, no I didn't weigh out the lead. Then you'd be interested in the suggestions Tony Bingellis had in his book "The Sportplane Builder". He suggested rigging the aileron up such that it was pivoted on it's hinge line. Then you install the tube that you will be using to pour the molten lead into and hang a bucket on it. Start tossing lead weights in. When the aileron goes neutral, stop throwing the weights in. Now weigh what you've got, bucket, tube and all, and pile that much weight in lead onto the scale so that you've just duplicated what weight it took to achieve neutrality. Melt that accumulation and pour it into the tube and you should be not sort of close, but exactly right. Don't stop by this week, I'll be down in NJ visiting the inlaws. I'd like to see your project too. Corky +++ #7821 From: Russ and Penny Erb Subject: RE: Pouring lead for the counterbalanced ailerons The only reason I would give would be to avoid dissimilar corrosion between the tube and the aileron. The lead is so non-active that corrosion between the lead and tube shouldn't be a problem. For those who haven't started their aileron ribs, I've been suggesting using a 7/8" steel rod instead of messing with the lead. Russ Erb +++ #7822 From: "Bruce A. Frank" Subject: Balancing Ailerons I have a question about balancing ailerons. The wings of my project are essentially those of a Super Cub with the standard ailerons which are not balanced. What could I gain if I balanced my ailerons. Someplace I read a note saying that the Super Cub had a Vne of about 147 MPH. Can this be because of the chance of flutter due to lack of balance weight in the ailerons? Anyone with 2 cents worth, or more, chime in. Bruce A. Frank +++ #7823 From: "Joe Hemmer" Subject: Re: Balancing Ailerons Bruce, since I know as little as anyone, here you are: Flutter. That is all, just flutter. On the other hand, I balance these things just because it seems like a good way to do things, and presumably gives me a little extra margin in case something else gets screwed up. I am a student of the Great Prophet Murphy. Or, alternatively, why not balance them? Joe Hemmer +++ #7824 From: sonny cilley Subject: balance tubes the reason for using aluminum is to not get into dis similar metal problems, and besides I believe the plans call for the 3/4" aluminum tubes. and as far as weighing out the lead that goes in the balance tubes, I would rather start heavy and drill out some lead as needed to balance. Sonny #234 +++ #7826 From: Tim Hickey Subject: Re: Balancing Ailerons Don't know all that much about flutter, but I can tell you about my experience with the Zenith CH-300 that I built. The Zenith design always seemed to be a "Work-in-process". I built my plane from plans. When you bought a set of plans from Chris Heintz for the CH-300, you got a set of plans for the 200, and an additional set of plans that told you what to change on the 200 to turn it into a 300. It was not the best of arrangements, but I can understand why Heintz did not want to redraw every drawing when he could just issue a set of changes and convey the same information. All of his drawings were more like really good sketches as compared to engineering drawings. This was well before AutoCAD. The plans did contain some errors, and many builders did find better ways to modify things to make the final product better. (at least for the builder with the "better Idea"). Heintz would send out a newsletter 4 times a year with updates or corrections to the plans. And there were more than a couple. And some were more important than others. Which leads me to flutter. In the beginning Chris Heintz did not recommend balance weights for the ailerons on the 300. His position was that if you keep the aileron cables set to the proper tension, 45 lbs., as I recall, there would be no flutter. So I built my 300 without balance weights. During the test flying I could look out the window and see the trailing edge of the aileron "moving" up and down about a 1/4 to 3/8 of an inch in total amplitude. I could feel nothing in the stick. The aileron was moving up and down about 3 times a second. I think that the magnitude of the movement was the amount of clearance between all of the rod ends and bell crank up to the cable connection. I guess that this movement would not be called flutter, because it was not increasing in amplitude and always seemed to stay under control. But I didn't like it. About this time Heintz came out with a design for balance weights and a statement that said something like,,, "well, if you really want balance weights, here is how to do it." He used a piece of streamlined tubing with a mounting flange, and filled it with lead. I built some balance weights, not exactly like his, put them on the ailerons, and this "killed" the movement of the ailerons. So, was this flutter? Did I really need that balance weights? (total weight of about 7 pounds, as I recall) I don't know. But I feel better about the whole situation. As much as anything, it shows me that there is a real need for some form of network where builders can exchange ideas and results. When I was building there was no internet. The only flow of information was either through the designer's newsletter, (totally controlled by the designer), or by going through a lot of work and making contact with other builders on your own. Chris Heintz designed a fine plane. I have over 1250 hours on mine, and from the way things look today, the airframe could last 12,000. I have had no trouble with the airframe at all. (Well, that is not quite true. I had to replace the horizontal tail hinges last year, and that was a bit of a chore.) (This year I think I will have to open up the flaps and re-do the flap mounting arms. This will be a bigger chore.) Both of these problems could be avoided if the next builder knew what I now know. Which brings me back to the value of exchanging ideas and results. It is the results part that take some time to get. Heintz's design was not perfect. I don't think any of them are. As you are building your project, ask yourself the following: Is this a good design? (the part under construction, not the whole plane) How long will it last? And when it does wear out, how will I fix/replace it? Time in service is a great judge of fine design. That's my story, and I'm sticking to it. Tim Hickey +++ #7828 From: Budd Davisson Subject: Re: Flutter/Balancing Ailerons Re: balancing and flutter There are two facts of aerodynamics that will always guarantee that test pilots have work: spins and flutter. You can calculate and cyber-model them to death, but when it comes right down to it, the only way you know what an airplane will actually do in regards to spins and/or flutter is to go up and try it. Flutter is a specialty unto its own and I don't pretend to understand much more than I got from some of my flutter classes in college and what I've gained from various test programs, all of which included testing for flutter. There is a general misunderstanding that flutter is a function of speed, which it definitely is not. You can get flutter at ANY speed, it's just that it happens more often at higher speeds. For instance, the designer of the Quail and Scamp airplanes was killed by flutter at about 65 mph. Also, you can easily have a flutter range in an airplane where it is flown regularly, but never see the flutter until the right combination of physical parameters (load, turbulence, etc) set it off. Some things contribute to flutter, other things work against it. One of the things you check for in ground shaker tests with a new design is to establish the natural vibrating frequencies of different parts of the airplane and make sure none of them are multiples (nodes) of another or the tail, for instance, could start vibrating (actually vibrating, not shaking) and it's oscillations could get sympathetic vibes goin in the wing. In this same area, the stiffer a structure, the higher its frequency and the lower the amplitude of its natural vibrations, so it is less likely to vibrate and it's easier to guarantee it's at a different frequency than another part of the airframe. Also, a structurally soft wing or stab structure can be forced to flex by the aileron or elevator and help feed surface flutter. Pure torque tube aileron systems (the torque tube lines up with the ileron spar and twists with it) can flutter because the torque tube can twist and untwist like a rubber bar and feed the flutter. Lots of system friction (Super cubs) fights flutter because it is a natural damping force. Balancing almost guarantees there will be no flutter because it damps the movements. The operative word is "almost guarantees". The only way to know if a new design has flutter is to start at a slow speed, below cruise, work up in increments (I like two knots, but most do it in five knot increments), excite each of the controls and monitor each displacement looking for a change in its damping. That's why I like 2 knot increments: you are more likely to spot the damping starting to decrease, rather than blundering into the flutter range. One of the other guys summed it up when he said balancing may not be worth it every time, but it's a fact that it doesn't hurt anything. again, I ramble. bd +++ #7831 From: Ken Beanlands Subject: Re: Balancing Ailerons THe Vne can be determined by any one of several concerns. THese include increasing control forces overstressing hinges, control flutter, roll reversal, stabilizer flutter, wing strut buckling, G-loading due to gust loads at higher speeds, windshields buckling, etc. THe only real way to tell is to take the plane to Vne and see what happens or by digging up the original design and flight test notes. Of course, some designers will pick an airspeed significantly above the 100% power cruise speed and demonstrate that speed. If nothing occurs at that speed, then that's the Vne. Not very scientific, but it works well. Granted, this approach is more common with smaller shops and homebuilt designers. Ken Beanlands B.Eng (Aerospace) +++ #7833 From: Budd Davisson Subject: Re: overbalancing It is common to balance 105-107%, but it is just as common to balance to 97% and I can't address the advantages of either. bd +++ #7840 From: Russ and Penny Erb Subject: RE: overbalancing Okay, budd, riddle me this... I know what 100% balanced means, as in the cg is right at the hingeline. But what does 105% balanced or 97% balanced mean? How is that number calculated? I could think of several possible answers, but I can't find confirmation of what is "correct". Russ Erb +++ #7843 From: Budd Davisson Subject: Re: overbalancing 107% is 7% more than is necessary (over balanced), 97% is 3% underbalanced. Some people swear by one or the other, but I can't address either. bd +++ #7845 From: snorttheoneandonly@y... Subject: Re: overbalancing So now it's conclusive: Overbalancing is definitely...not so conclusive. I did a brief detour into google-land search engine results with these results: Generally, you do not want to balance 100% because overbalancing can aggravate the flutter problem. This is where things get kind of touchy feely. In general you want to load the surface somewhat to take the slop out of the control system. 90% to 95% balance comes to mind. Jim Doyle Stress Analyst (I'll have to find the URL again on this one) http://naca.larc.nasa.gov/1949-cit.html (I didn't bother opening all the pages to read this. Someone with more patience might want to). www.bouyea.net/digests/1999/19990215.txt ... not have balance weights on the ailerons. Anyway the weight it takes to ... From a flutter standpoint, a little overbalancing is better than underbalancing. All things considered, I'd leave this one to the test pilots out there. Geez, there must have been someone who experimented with these angles at some point in the history of airplane flight. Not a good sign they didn't leave a record! Happy flying! John W. +++ #7847 From: Russ and Penny Erb Subject: RE: overbalancing Okay, that's still not clear to me. Are you saying if it would take 10 lbs of ballast to perfectly balance the surface, 107% would mean that you used 10.7 lbs? Russ Erb +++ #7849 From: Budd Davisson Subject: Re: overbalancing yes. bd +++ #7894 From: bubba jones Subject: Another method for pouring lead Something that I have done with great success on large RC gliders is to mix lead shot (usually No.8 or 7.5 because I have a bunch of it from trap shooting days) with very thin (less Viscous) epoxy and pour the lead shot and epoxy mixture down the ballast tube. If you fill too much you can drill it out. cover the ends with tape and let it set. Most hunting/fishing sporting goods store carry lead shot The advantage is that you do not deal with molten lead and the entire tube is filled with ease. Use the overnight epoxy not the short duration one. You may apply some heat from a heat gun or a hair dryer to make the epoxy less viscous so it flows better in the tube. Caution DO NOT USE THE WIFE's GOOD DRYER. Been there got shot Will report progress on 505 soon. Have been doing tons of prep work. Varun 505 Khanna +++ #7898 From: Russ and Penny Erb Subject: RE: Another method for pouring lead That's a good method, and I used essentially that method to balance my elevators. As for the ailerons, I tried it and it didn't work. If you use the plans recommended size tube, it has to be pretty much full of lead to be heavy enough (about 5.5 lbs). I poured lead shot (No. 8) into the tube and couldn't get more than about 3.5 lbs. I ended up pounding lead wool into the tube, which worked out well. Russ Erb +++ #8115 From: bearhawk39@a... Subject: Re: Re:rivet question Why the stainless rivets on the aileron and flap nose skins? Is this strictly a corrosion problem or is strength the issue? Does any one have a good source for these (a little pricey). +++ #8116 From: Tim Hickey Subject: Re: Re:rivet question Interesting question. I don't know the answer to it, but Chris Heintz of the Zenith outfit always poo-pooed (read advised against) using stainless in contact with aluminum. Something about the position of each material in a listing of metals where the one above will eat (corrode) the ones below. And the farther apart the metals are, the faster the lower one will disappear. We need a metallurgist or someone who remembers a lot more about this than I do. It was Heintzs' position that if you used stainless steel as a fastener, that the aluminum would eventually disappear.(corrode) And that if you used a standard steel fastener, and if it corroded, or maybe when it corroded, you could more easily replace the fastener than you could the aluminum. I don't know the absolutes of this, but I bet someone out there in this group does. Tim Hickey +++ #8118 From: "Del Rawlins" Subject: Re: Re:rivet question We've seen this question enough times now that I guess I need to get off my duff and put it in the FAQ. There was an engineering notice in the July '99 Bear-Tracks in which Bob said to use 1/8" aluminum rivets instead, but if you have already used the 3/32" SS rivets to go ahead and leave them alone, since they work fine. This applies to plans #395 and below. Del Rawlins +++ #8120 From: charles.eyanson@u... Subject: Re:rivet question Okay, this brings up a related question. I have planset #397 and it does specify aluminum rivets for the flap and aileron nose skins, but still specifies 1/8 SS pop rivets for the trailing edge. Does anyone know if it was Bob's intent that aluminum rivets be used all around the aileron and flap or is SS still the material of choice for the trailing edge rivets? Chad Eyanson +++ #8121 From: "Bruce A. Frank" Subject: Re: Re:rivet question This idea that stainless in contact with aluminum will cause corrosion of the aluminum has been knocking around for years and regardless of what one thinks can be deduced from a periodic chart problems aren't widely evident. There has to be galvanic reactivity between two metals for one to be sacrificed. The alloys of stainless are passive in the environment of stainless rivets used in aluminum fabrication. I have built enclosed utility trailers using both 6061 and 2024 (non-alclad is a poor choice for a utility trailer, but it was surplus) aluminum. The trailers were assembled using several different kinds of rivets and methods. None of the aluminum was painted before or after assembly. I was buying surplus rivets of both solid drive rivets and pull (pop rivets, some structural kinds marked Avex) type. All trailers were riveted with whatever I had on hand at the time. I used aluminum pop, stainless pop, tin plated copper pop, zinc plated steel pop, aluminum driven, tin plated copper driven, and monel drive and pop type. I was contracted to build 10 trailers. I started with driven rivets and after three assembled that way I went to pop type strictly because of speed. The skins were not structural but were stressed by the flex of the trailer frame in almost 100% off road use. I maintained these trailers mechanically for about 6 years at which time all of them were scrapped which had been the plan from the beginning (thus the lack of any attempt to protect from corrosion during original assembly). By the end of that six year period I had replaced all the lower skins on the trailers fabricated from un-clad 2024 (unpainted plywood floors just kept on going). The aluminum was exposed to both alkali dust and salt (off road in Utah). All corroded about the same whether riveted with aluminum, stainless, monel, copper or plated steel. Corrosion was concentrated around the rivets and overlap of the skins due to the retention of moisture in these areas. There was no sealant used between skins or in the rivet holes before the rivets were set. Panel skins places higher on the trailers (away from wheel splash) showed corrosion, but none to the point that rivets pulled through. The corroded skins were removed by driving a thin chisel between the skins overlap to overstress the rivets and zipper the panels off. Ninety percent of the time the skin failed leaving a serviceable rivet still in place (in that 10% the plated steel failed as frequently as the aluminum pop rivets). Now my point here is that none of the different rivets showed any more or less corrosion of the aluminum skin around the rivet holes. The plated steel and the aluminum rivets were corroded. The Monel, stainless and copper were not. The tops of the trailer's skins if fabricated from 2024 had slight corrosion over the whole surface with little to no acceleration around overlaps or around the rivets regardless of the rivet material. The 6061 skins were corroded slightly around all types of rivets in the lower panels, but there was never a need to replace any of the skin. What corrosion that did exist was highest around the aluminum rivets and the plated steel rivets. The tin plated copper, the stainless steel and monel were identical in their adjacent corrosion and lack there of. Certainly mine wasn't a technically analytical observation of the performance of stainless rivets versus aluminum rivets, but I have filed away my observations to guide my future selection of pull type (including Avex) rivets in aluminum. I have also seen a statement from one of the kit plane manufacturers (wish I could remember which one) that found that their use of stainless rivets in aluminum components and skins has shown on corrosion problems in application for 20 years of service. Bruce A. Frank BTW, each trailer contained a combined total of almost four thousand 1/8", 5/32" and 1/4" rivets. The first one fabricated with pull type rivets I did with a manual puller. I quickly went out and bought a pneumatic puller, but my right hand was so beaten up from the manual puller I had to use the pneumatic in my left hand for almost two weeks. +++ #8123 From: Russ and Penny Erb Subject: RE: Re:rivet question > Does anyone know if it was Bob's intent that aluminum rivets > be used all around the aileron and flap or is SS still the > material of choice for the trailing edge rivets? Yep. 1/8 Aluminum in the leading edge, 1/8 stainless in the trailing edge. Russ Erb +++ #8126 From: "Hall Brothers" Subject: Re: Re:rivet question More Rivet Opinion - I agree that stainless steel pop rivets in aluminum will not have a corrosion problem especially if the aluminum is primed. Some builders/designers use aluminum just because they are cheaper and they're easy to drill out when you make mistakes. Both are bad reasons. Here's a test I have done to get a feel for the different rivets: Cut some strips of .025 or .032 2024-T3 aluminum sheet about 1 inch wide by 2 or 3 inches long. Drill a #30 hole about a half inch from the end of each strip. Overlap and rivet two pieces together so the overall length is now about 5 inches. Put one end in the bench vise and grab the other end with large vise grips and pry them a part under tension, not peeling. You might need a block of wood to get the spacing between the vise grips and vise just right. Hope this makes sense. Anyway, try an aluminum pop rivet, a stainless steel pop rivet, and a solid aluminum AN rivet. The difference is dramatic! The aluminum pop rivets usually shear right off, hardly even deforming the hole, while the stainless and solid aluminum rivets are much stronger. I only use aluminum pop rivets in lightly loaded or non-structural applications. LH +++ #8129 From: "Lee H. Erb" Subject: Re: Re:rivet question > This idea that stainless in contact with aluminum will cause > corrosion of the aluminum has been knocking around for years > and regardless of what one thinks can be deduced from a > periodic chart problems aren't widely evident. Bruce is correct. Stainless steel rivets in aluminum sheet is standard aircraft practice where extra rivet strength is desired. Especially for blind rivets. See Chapter 1000 web page. Technical Articles, Index to Corrosion Articles, Galvanic Table, More on Galvanic Table, The (non-aerodynmic) Area Rule, Corollary V Lee H. Erb +++ #8130 From: Tim Hickey Subject: Re: Re:rivet question Thanks for the input. This makes me wonder that perhaps there needs to be some kind of balance between the type of rivet, the thickness of the rivet, the thickness of the aluminum sheet, the type of aluminum sheet, and the type of loads to be resisted. If a stronger rivet (such as a SS one) was a requirement for resisting loads, would not a few more standard solid rivets be an acceptable substitute? I know that there are center-to-center rivet spacing guidelines, (reminds me of the old story about the toilet paper) but somewhere there must be a recognition that the aluminum sheet may be the first point of failure, while the rivet survives quite nicely. This seems hard for me to put into words, but to have the rivet survive and the sheet fail is not a good thing. Perhaps having a SS rivet is overkill, because the sheet will fail around it. In other words, if a joint requires a strong rivet like stainless, will not the extra strength of the rivet be wasted because the sheet can never develop loads to a point where the extra strength is utilized? Tiz a puzzle for me. Insight requested Tim Hickey +++ #8131 From: "Bruce A. Frank" Subject: Re: Re:rivet question Most of the time one uses a pull type rivet when it is not possible to get to the back side to buck it. OR when the strength of a driven rivet is overkill or more trouble than necessary simply because the pull rivet is adequate. Bruce A. Frank +++ #8133 From: "Del Rawlins" Subject: Re: Re:rivet question It sounds like except for the additional cost, there isn't really any drawback to just using 1/8" stainless steel rivets throughout the flaps and ailerons, including the leading edge skins where Bob said a 1/8" aluminum rivet is okay. Del Rawlins +++ #8134 From: "Lee H. Erb" Subject: Re: Re:rivet question > It sounds like except for the additional cost... It is not quite that simple. It may take a couple of weeks for me to put together a good story on selecting rivet size, type, number, etc. Also there comes the time to use a "Cherry Max" steel permanent fastner. Riveting a patch over a crack has simple rules outlined in AC 43-13 but is an overkill from normal structural design. Use of fastners (a rivet is a fastner) is a very large subject for a designer because there are so many options. Many times it gets down to "we have always done it this way." I am a firm believer in installing rivets "wet." Lee +++ #8135 From: "Del Rawlins" Subject: Re: Re:rivet question I guess I should have clarified that to say wherever 1/8 or 3/32 ss pulled rivets are specified by the plans. I didn't mean to suggest using them instead of the solid rivets (yikes), if that is what you are getting at. I was just thinking that if 3/32 ss and 1/8 aluminum pulled rivets are both acceptable, then 1/8" ss rivets should be fine as well. Then again, I'm not an engineer. +++ #8136 From: Russ and Penny Erb Subject: RE: Re:rivet question I did find that the stainless rivets were harder to pull with a hand puller. With the pneumatic puller it was a non-issue. Russ Erb +++ #8138 From: "Lee H. Erb" Subject: Re: Re:rivet question > Then again, I'm not an engineer. Don't worry about that. Engineers with 50 years experience don't know much. I'll take advice from any good builder/mechanic anytime. Your advice has always been good. I'll see if I can add some clarification as to why designers/stress engineers callout the rivets they do (sometime in the future). (Right now I have another 4 to 6 hours to go on a take-home test on soil fertility/fertilizers. It is a completely different set of data than aircraft design/fab but is definitly challenging.) Lee >>> 4sep02 #9154-11297 +++ #9166 From: Russ and Penny Erb Subject: RE: counter balance tubes > Anybody recall of the top of there head what the aileron counter > balance tubes should weight? My calculations for my ailerons came up with a desired 5.275 pounds. My balance tubes ended up at 5 lb 5.2 oz and 5 lb 0 oz. The ailerons are covered and hanging from their hinges now and quite happily sitting horizontally, so I'm happy with the balance. Your required weight will depend on how you build your ailerons. Simple answer: If you are going with the tube as designed, stuff it as full of lead as possible and you'll get about the right weight. If you haven't built the aileron nose ribs, consider using a steel rod 7/8" diameter instead. It's only 1/8" bigger in diameter, and you can get sufficient weight with a rod shorter than the aluminum tube shown in the design. The good side is you don't have to mess with lead. The down side is that you will need to develop a method to secure the rod in place. One option is to drill and tap holes instead of using pop rivets. (In the system as designed, the pop rivet pushes the soft lead out of the way and grips the aluminum tube.) +++ #9174 From: Russ and Penny Erb Subject: RE: Aileron weight > Would you mind weighing the ailerons and give us a number? I'm not sure what Jim was asking for, but here's the data. Make your own conclusions. Aileron Frame: 5.9 lbs Balance Weight: 5.325 lbs Fabric: 1 lb Total: 12.225 lbs +++ #9565 From: "Javier Garza" supermexgarza@... Subject: Aileron nose rib On the aileron nose rib drawing, the plans shows the full scale nose rib with some notches for the flange on the curve, and the 3/4 dia cut out for the pipe full of lead to balance the aileron, if you check for square on the bottom side and the vertical where the aileron spar goes is NOT SQUARE is that the way it is or should it be square/ drawing calls for 8 right and 8 left i im working on a samll wood block but i got hung up on this. +++ #9566 From: "Kevin Deutscher" bearhwk272@... Subject: Re: Aileron nose rib-- Answer ? Q. if you check for square on the bottom side and the vertical where the aileron spar goes is NOT SQUARE is that the way it is or should it be square/ A. NOT SQUARE. +++ #9567 From: Russ and Penny Erb Subject: RE: Aileron nose rib-- Answer ? If you could look at the whole airfoil, you would see that when the spar is vertical, the lower surface is not horizontal. That's just the way it is. >>> 20may03 #11298-18250 +++ #11503 From: Ken Beanlands Subject: Ailerons I was recently re-reading Budd's article on Proto II and noticed the reference to a change in the aileron design between Proto I and II, specifically the location of the hingeline. "The ailerons, which had been a little stodgy, had been lightened up by moving the hinge point back. The result is a nice, responsive, Beechcraft-like feel with a little higher roll rate." Can anyone tell me which version would be on teh plans? specifically, plans set 468? What is the difference in dimensions between the two? Are there suplimental drawings to change the old ailerons to the new? Thanks, Ken Beanlands B.Eng (Aerospace) +++ #11504 From: Budd Davisson Subject: Re: Ailerons Bob told me that he never put out plans with the old ailerons. All plans have the hinge line moved back. bd +++ #11843 From: pfflyerz@c... Subject: control surface balance There was quite a discussion a while back about how to balance the control surfaces with various estimated weights and techniques bandied about. Now that my surfaces are have finish paint I rechecked them for balance. I used Erbman's estimate for elevator weight and came up 8 oz. light in each elevator. I was able to solve that problem easy enough by drilling through the T25 channel, at the elevator tip and pouring a lead shot/resin mixture into the elevator tube. I next checked the ailerons and found I was 2.5 lbs light in each of them. Although I didn't pour my aileron balance tube with molten lead, I think I came pretty close to filling it up by pouring a lead plug on one end, filling with lead shot, then pouring another plug on the other end. All that primer and nice shiny paint must really add up if Bob was able to balance his with just that central tube. I can add 2.5 lbs by almost filling two more tubes and placing them in the remaining leading edges. I cut a hole in the fabric to allow me to slide the tube in, but I will have to drill out the rivets holding the skin to the ribs as they are preventing me from inserting the tube. Just a heads up for those of you that haven't gotten to that point yet. Pat Fagan +++ #11864 From: Russ and Penny Erb Subject: RE: control surface balance Pat--when you say you used my estimate for "elevator weight" did you mean my estimated fabric weight or counterbalance weight? If you just filled your aileron balance tubes with lead shot, I'm not surprised that you would be 2.5 lbs light--that's very consistent with what I saw when I tried the same thing. That's why I went to pounding in lead wool. I filled the tube and would have liked about half a pound more. For those who haven't made their aileron ribs yet, I still think a 7/8" steel rod would be a better way to balance the aileron. Needs bigger holes in the nose ribs, though. Russ Erb +++ #11866 From: pfflyerz@cs.com Subject: Re: control surface balance > when you say you used my estimate for "elevator weight" did you mean > my estimated fabric weight or counterbalance weight? Estimated counterbalance weight. Pat Fagan #232 +++ #11878 From: sonny cilley Subject: Re: Digest Number 933 So Russ and Pat, what did your aileron balance tubes end up weighing? I poured mine with hot lead and off the top of my head I think they were around 5.75 lbs. each, is that within the ball park ,or am I off base. Sonny, # 234 +++ #11881 From: Russ and Penny Erb Subject: RE: Digest Number 933 > From the Bearhawk CD, the finished tubes were 5.2 and 5.0 lbs using > lead wool pounded in. The theoretical maximum is 6.01 lbs. My > ailerons needed between 5.275 and 5.8 lbs, but the tubes as produced > were adequate, and they balance quite nicely with the fabric on. Russ Erb +++ #11893 From: pfflyerz@c... Subject: Re: balance tubes > what did your aileron balance tubes end up weighing? I wish I knew, but I never weighed the large tube before installing it. Based on the size and weight of the two tubes I plan to install, I would guess the weight must be close to 7 lbs. Pat Fagan #232 +++ #14170 From: Benton Holzwarth Subject: Fabric Planes & Drains Reading through an article in EAA Experimenter (Bob Whittier's 'Light Plane Heritage'; Aug '02), the author was talking about wood rot, and among other things, the need for 'drains' at the low points of each bay in the control surfaces. Wood rot doesn't apply to the Bearhawk, but is it customary to include the drains in land and/or seaplanes even if fabric over Aluminum? I've wondered about since seeing 'em on other fabric planes (of unknown to me internal construction.) Benton +++ #14174 From: Pat Fagan Subject: Re: Fabric Planes & Drains The poly fiber covering manual says to include the drains regardless of the wing structure material. Pat Fagan +++ #14177 From: "Bruce A. Frank" Subject: Re: Fabric Planes & Drains Yes, all you need is an aileron full of water (or ice). Bruce (we had frost here in San Jose this morning) Frank +++ #14187 From: Ken Beanlands Subject: Re: Fabric Planes & Drains They should also be installed in teh tail surfaces and under the belly. A good rule of thumb is it add a drain anywhere water or moisture can hang up. I used seaplane grommets throughout (these are little plastic dimples with the rear edge opened for venting) and even added them to the vertical stabilizer and fin. One thing to note, most taildraggers are stored with the elevator in the up position. Since the plane spends most of it's life on the ground, your drain grommets should be at the leading edge of the elevator, not the trailing edge. I almost got caught on that one. Ken Beanlands B.Eng (Aerospace) +++ #14190 From: Bob Romanko Subject: RE: Fabric Planes & Drains One other thing about drains, they don't weigh anything (unless you're Bob Barrows...grin!) and you can put 'em where you THINK you need them and punch 'em out as required. The other thing is don't think you can look at a rag 'n tube plane on the ramp and copy where they put their holes. That bird was most likely recovered, and there's no telling whether that guy knew where to put 'em either. It's better to err on the side of too many drains than not enough, for obvious reasons. Planter Bob +++ #14200 From: "handainc" Subject: Re: Fabric Planes & Drains I'm sure a lot of guys on here have a lot more knowledge than I, but messing with old airplanes for the last 20 years, off and on, it is mandatory to have drains - a quick list below. Water collects in low points on a taildragger, then - 1. It can cause an out-of- balance condition for control surfaces. 2. Sets up corrosion. 3. Builds up dirt and deposits. 4. May deteriorate the fabric (esp. on older non-synthetic coverings). 5. Freezes and expands to cause structural damage and further out-of-balance control surface. I'm sure there are probably more - but that is my experience. M. Haught +++ #14203 From: Ken Beanlands Subject: RE: Fabric Planes & Drains Remember though, that if you use seaplane grommets, you need to burn the holes in teh fabric BEFORE installing the grommet. The way they are designed will prevent you from getting at the fabric underneath after the fact to cut your holes. Ken Beanlands B.Eng (Aerospace) +++ #14695 From: "t18cox" Subject: Control stops Bob is clear about the rudder and elevator stops. I don't see an obvious aileron stop. I have been rigging my ailerons and when the bottom of the stick hits the large tube in the walking beam I have about 20 degrees travel. That is probably dumb luck. I think most certified aircraft have a stop near the surface. The T18 as designed only had a stop at the walking beam and in 1100 hrs of operation that has never been a problem. Any thoughts on aileron stops? By the way I limited the trim tab travel by welding a couple of tabs on the top longeron to bear against the bellcrank. Bill Cox #303 +++ #14703 From: Del Rawlins Subject: Re: Control stops > Bob is clear about the rudder and elevator stops. This might be a subject worth calling The Bob about. I wouldn't be a bit surprised to learn that he designed it to be self limiting this way on purpose. -- Del Rawlins +++ #14713 From: Russ and Penny Erb Subject: RE: Control stops You are very perceptive, Grasshopper. Pat Fagan added some additional stops at the bottom of the control stick, but as designed, there are no stops at the ailerons. I always figured what you described was the intended stop. Thanks to cable stretch, the ailerons will still be able to move slightly when "on the stops". I have yet to form an opinion on whether this is a problem--but I haven't changed the design either. Russ Erb +++ #14715 From: "t18cox" Subject: Re: Control stops Thanks for the input. I called Bob tonight and he confirmed that is his stop. I'm not real comfortable with that so I'm adding a stop that is a little more substantial. Unless I discover something else I am ready to clean and paint the fuselage and move on to the covering stage. The weather here is really wet and cool now, (Typical gulf coast winter)so it may be a few weeks before blasting and painting starts. Bill Cox #303 +++ #14718 From: Budd Davisson Subject: Re: Control stops A Pitts has no aileron stops. They are on the stick. Think about a double, outside snap roll or a lomcevak and it makes you a believer in stick mounted stops. Of course, it's also a pushrod system. bd +++ #14720 From: pfflyerz@c... Subject: Re: Control stops I added aileron stops to my sticks by welding a bracket, with at set screw in it, to the lower portion of the stick. The set screw hits against the flange on the back side of the stick tower. Seems to work well. If this is not clear, I can take a picture for you. Pat Fagan +++ #14774 From: Pat Fagan Subject: the revolutionary wing diet It sounds just as amazing as all those weight loss nostrums you hear about add nausem, but I no longer have a heavy right wing. My hanger mate came back from vacation today and I took him up for an evaluation of the problem. We landed and, after verifying the geometry of the bell cranks looked correct, he proceeded to squeeze down the trailing edge of the left aileron, just a little, with some paint sticks and channel lock pliers. He wanted to do it incrementally so we went back up and, surprise, almost perfect. It was close enough that he didn't feel we should try for any more. Apparently this a technique the RV boys use a lot. [ additional posts in $6.2 - Flight Ops ] +++ #15265 From: Del Rawlins Subject: Re: Aileron/Flap lightening hole centers > Well, the nose ribs are done, on to the aileron and flap ribs. > > Since the centers of the lightening holes on these ribs are not > marked on the mylar and no dimensions given on the plans, I assume > folks just scale it from the drawings? Bingo. -- Del Rawlins +++ #15300 From: "kb8rnu" Subject: Another Aileron and Rib Question While scaling the drawings of the aileron ribs for the hole centers I noticed a major discrepancy in the size of the rib on the drawing vs. the mylar. If you double the measurement of the length between the aileron spar and the trailing edge tip, it's off by nearly an inch. from that distance on the mylar. I assume it should be built to the mylar? Has anybody else seen this? The flap drawing length is off as well - have the control surfaces been changed in length or something? Thanks! Jason +++ #15313 From: Benton Holzwarth Subject: re: Another Aileron and Rib Question > If you double the measurement of the length between the aileron spar > and the trailing edge tip, it's off by nearly an inch from that > distance on the mylar. Is it that the mylar shows the length of the rib proper, but the drawing is showing the trailing edge attached, which projects about another bit beyond that? My block (and metal parts) show the flap ribs as 16 5/8" from stem to stern, and when I take a scale to my xerox copy of the plans, the flap shown in the lower right corner of sheet 9 scales out as 16 3/8" -- note that the trailing edge material projects a little further beyond this. Benton +++ #15321 From: "kb8rnu" Subject: Re: Another Aileron and Rib Question (solved) Thank you very much, Benton. That's what it was. Once I realized that the trailing edge stuck out past the rib a bit it all fell together. Time to start cranking out flaps and ailerons... Thanks again. Jason +++ #16625 From: "kb8rnu" Subject: Aileron rib forming note... A note to the guys who have just started forming ribs: I found it much easier to get consistent results on the trailing edge of the aileron ribs if I left a little extra metal (about 1/4" in addition to the allowance for the 1/2" flange) and then trim it to size after forming. I would assume flap ribs would work similarly. Have any of you more experienced folks seen this? My apologies if it's old hat to everybody. Jason +++ #16632 From: del@r... Subject: Re: Re: Aileron rib forming note... > Another note on the ailerons: The lighting holes are drawn wrong and > I talked to the "BOB" after it was too late. The lighting holes need > to be smaller than are drawn or scaled. Building to the plans means > real tight "BOB sticking" for the flanges. He suggested on making > new ones, yea right like I din't have anthing better to do. Smaller > holes are OK or use the bigger holes and suffer the tight flanging. I think this is the first mention of this "problem" here on the list. I made my aileron ribs per plans, and didn't have any trouble with this size of the lightening holes, or forming the flanges with a bob stick. Even if they are a little large, it isn't like the wing ribs where vertical stiffeners need to fit between the holes. Besides, the less material you remove in the form of lightening holes, just means more lead will be required in the leading edge to balance the aileron, and the balance tube just barely holds enough to begin with. Del Rawlins +++ #16639 From: Russ and Penny Erb Subject: RE: Re: Aileron rib forming note... Because of the system I used to build my ribs (jigs and evil flanging dies), I ignored the lightening holes drawn on the aileron and flap drawings and put the lightening holes in the same locations and sizes as shown for the back and tip ribs. I preferred the consistency to a possible saving of an ounce of weight or so. Russ Erb +++ #17606 From: pfflyerz@c... Subject: Re: fabric weight When you estimate the weight for the counterweights, err considerably on the heavy side. I used the estimated weight that Russ came up with, but after using the heavy weight fabric on my tail surfaces, and all that shiny paint, I had to add some more. I was able to do that without messing up my paint by drilling through the end rib on the elevator and pouring a resin/lead slurry into the tubing structure of the elevator. If you find after paint that it is too heavy, you could always drill some of it out, in the same way, and it really wouldn't show. Pat Fagan +++ $Id: 2.1.5-Wing-Aileron,v 1.10 2003/05/21 14:59:49 bentonh Exp $