Eagler's Nest
Airframes => Single Seaters => Topic started by: jrbirdman47 on January 25, 2020, 03:48:56 AM
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Frustrated doesn't come close to describing how I feel about the aileron well. I built the wings using Iron Designs plans. The wings are essentially finished, I just need to glue the aluminum in the aileron well. I'm using flashing material, so cheap and easy, right? I am on my fourth attempt now.
First, it's not easy to find a way to bend something 6 1/2 feet long, so that in itself is a problem, but once found, the real challenge begins. I made a template out of the same material which would lay in the well, contacting the K block, and bending so as to fit perfectly on the upper and lower surfaces of the well. I bent flashing to those exact dimensions and it doesn't fit. It "hangs" from the upper and lower surfaces without contacting the K blocks. A quick trial proves my suspicions and there is a slight rub when the aileron is moved.
Back to the workbench. I added 1/8" to the dimension in contact with the K block, figuring this added length would allow the metal to contact the K block and lay on the upper and lower well perfectly.
Nope. It contacts the K blocks, but if, say, the upper surface is clamped together,(wood to metal), then the opposite side hovers about 1/8" high. Back to the workbench!
Split the difference, right? Nope. Hangs from the upper and lower surface without contacting the K blocks. Is it necessary to use a micrometer to lay it out? ::)
I took great pains to build the well as close to perfect as possible. The trailing edge of the upper and lower well, (plywood), all stand equal distance from the rear spar. I can stretch a string across the K blocks and they all follow the same arc.
Am I missing a way to do this that is so simple I can't see it?
If you've already done this, how did you accomplish it? Help save the sanity of an otherwise fairly normal guy.
Thanks!
Rick
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Frustrated doesn't come close to describing how I feel about the aileron well. I built the wings using Iron Designs plans. The wings are essentially finished, I just need to glue the aluminum in the aileron well. I'm using flashing material, so cheap and easy, right? I am on my fourth attempt now.
Yes, it looks like you have done a great job on the wings, and I have found the flashing material is as light as anything to fill the gap. So all good, please read on.
First, it's not easy to find a way to bend something 6 1/2 feet long,
certainly true with most having 4' breaks, we have done in sections with the splice VERY close to a supporting K block.. at .010 thou. the over lap is very slight.
so that in itself is a problem, but once found, the real challenge begins. I made a template out of the same material which would lay in the well, contacting the K block, and bending so as to fit perfectly on the upper and lower surfaces of the well.
I have found, that with a 2" or 4" piece this can be done as you described. But to do both the upper and lower bend and have them 100% parallel Which they have to be, is pretty tuff as you have found out. So have made, 55% width, top or bottom with one bend, and then the other half, also at 55% of width. (this 10% extra is the over lap) So if your off 1/32" or even less, and do the double bend, it will fight you, like I suspect it is doing. But the same degree of being off, but in two pieces, will be taken up by the over lap in the center and would take the sharpest of eye to ever see it. Hope that makes sense
I bent flashing to those exact dimensions and it doesn't fit. It "hangs" from the upper and lower surfaces without contacting the K blocks. A quick trial proves my suspicions and there is a slight rub when the aileron is moved.
There should be about 1/4" gap, if I remember correctly...so am guessing if you don't have the gap, the above is happening when making the cove material as one piece.?? Just thinking out loud here. With the aileron easy to put in and out you could make a could of very small test pieces and hold at each rib station, (should be able to move and check at each station without taking the aileron off) If this proves good, you know it is in the full piece bending, and not the actual gap.
Back to the workbench. I added 1/8" to the dimension in contact with the K block, figuring this added length would allow the metal to contact the K block and lay on the upper and lower well perfectly.
Nope. It contacts the K blocks, but if, say, the upper surface is clamped together,(wood to metal), then the opposite side hovers about 1/8" high. Back to the workbench!
In reading this, I am really suspecting the two bends not being 100% parallel Without doing the math, if you were off even by 1% , I am guessing you would have a slight twist, thus hitting as you prescribe.
Split the difference, right? Nope. Hangs from the upper and lower surface without contacting the K blocks. Is it necessary to use a micrometer to lay it out? ::)
shouldn't have to at all.
I took great pains to build the well as close to perfect as possible. The trailing edge of the upper and lower well, (plywood), all stand equal distance from the rear spar. I can stretch a string across the K blocks and they all follow the same arc.
Am I missing a way to do this that is so simple I can't see it?
If you've already done this, how did you accomplish it? Help save the sanity of an otherwise fairly normal guy.
Thanks!
Rick
Rick, I hope to have maybe answered some of your questions above... Please let us know.
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Sorry about the split note, I hit the wrong button, but to continue on, in bold.
I took great pains to build the well as close to perfect as possible. The trailing edge of the upper and lower well, (plywood), all stand equal distance from the rear spar. I can stretch a string across the K blocks and they all follow the same arc.
I am guessing almost for sure it is not in your rib building.
Am I missing a way to do this that is so simple I can't see it?
hopefully I have simplified the problem in the other message. :D
So to wrap it up, a couple little test bends in two pieces, should tell the story...as if they work, all the way across, this quickly tells that it is in the cove bending itself, not your wing building.
If the question comes up on how we bond, WE use 3M-2216 to bond to ribs and actually with correct rules followed you can bond alum to alum but we still use one 3/32 tear alum rivets per bay... (to prevent peel, ever) This is amazing material, but you will never be able to get the two apart once bonded. Measure twice/cut once type of a deal.
Best of success.
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Thanks Scott, The last iteration of the cove was done in a sheet metal shop using CAD/ CAM equipment to get precise cuts and parallel bends. Still no go. As you suggest, extremely small variations in the wood structure can greatly influence the fit of the metal though. I previously thought to make he thing in two or three sections as you suggested, mostly because I could use a 48" brake, but I now see the virtues of having fit in 2 or 3 sections as well. Thanks for your thoughts! I am in a work induced hiatus for a week, which gives me time to think it over and start fresh again when I get home. Meantime I'll look for the glue you indicated and scheme. Thanks again!
Rick
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been a few days since I did mine with the metal cove. I used a length of 3inch plastic sewer pipe with some thin foam sheeting against the metal and pressed it into the wing. could try that with the flat metal and then mark the two bend lines with a pencil, remove and bend
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When I did mine I found best results using jig blocks that actually have the inner curve based on CAD drawings I made but my jig blocks also wrapped around the edges an inch or so and helped me clamp the metal in place. I had one that did not fit correctly but next attempt did ok. I may have a slight flare on the top edge of one but so minor I am not worried about it.
(https://i0.wp.com/buildlog.virtualmakerspace.com/wp-content/uploads/sites/2/LegalEagleXL/IMG_20190319_194112.jpg?fit=1493%2C691)
you can see details in here - http://buildlog.virtualmakerspace.com/2019/04/10/aileron-inboard-aluminium-cap-and-strips/ (http://buildlog.virtualmakerspace.com/2019/04/10/aileron-inboard-aluminium-cap-and-strips/)
I share many of my CAD drawings here https://cloud.virtualmakerspace.com/s/6CiNKpPpFpWorwA including the jig file - K Block (spacer) v10 - K Block Compress Jig.dxf.
Of course, that works for me and may not be exactly right for you. I cut it out on my CNC Router but if desired anyone should be able to print it and cut it out on a bandsaw or what have you.
BTW, I also ended up having to remove and redo the first one (or second one?) because I failed to buff the metal before gluing and even as good as 2216 is. Second gluing went well with no issues.
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Thanks guys-
I used blocks cut to the same radius as the K blocks and clamped down as shown in the picture. I glued it in multiple stages: First glued the metal to the arc of the K block, then glue the metal to the top and then the bottom of the well. (Removing it without damaging the wood was TOUGH!) I think Scott's method of glueing it in sections will work because it is easier to work with a smaller section and it also allows for small variations in the aileron well and/ or metal.
I have a week to think it over and try again. Have no doubt of the outcome, I just wish it had worked the first try, but if this is the only setback during the wing construction I'll take it. I was amazed at how much stiffness the aluminum cove added to the well, (What short time it was in place), and I like it better than just fabric back there. I really loved working with the wood but look forward to doing so with steel next!
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For what its worth, I made my aileron well from some left over leading edge .8mm plywood. Very happy with result. With my limited workshop, was not able to bend the aluminium to fit nicely. Ended up wasting the stuff!!
Terry XL B-35
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The thought of using the .8mm to do this crossed my mind too. decided that flashing would be easier...... ::)
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Does anybody have an idea how much the aluminum cove cover weighs, compared to 0.8mm plywood? Since we already have practice curving the ply to cover the aileron nose, seems like the cove cover from 0.8mm would be fairly easy. At least it would bond well to the rest of the wood structure.
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Does anybody have an idea how much the aluminum cove cover weighs, compared to 0.8mm plywood? Since we already have practice curving the ply to cover the aileron nose, seems like the cove cover from 0.8mm would be fairly easy. At least it would bond well to the rest of the wood structure.
The wood is 25% lighter... Bare wood compared to bare metal.
The aluminum used for flashing material is 3125 alloy (https://www.suppliersonline.com/propertypages/3105.asp#Spec) and weighs .098 lbs per cubic inch. (google the alloy)
Aircraft Spruce states (https://www.aircraftspruce.com/catalog/wppages/finnishbirch.php) that a 1 square foot piece by 1/32 inches thick of 3 ply Finnish birch weighs .11 lbs. (down in the Q and A) That works out to 4.5 cubic inches and .0244 lbs per cubic inch. 12 in. X 12in. X .03125 in. = 4.5 cubic inches. .0244/.098 x 100 = 25%
Not what I was expecting, but the wood will have to have spar varnish or epoxy.
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Just to jump into the conversation, I was thinking about using fiberglass for my cove over the K blocks. Two layers laid up over a pipe should work for a thin light weight curved section. unlike metal it could be heated to adjust for minor irregularities when installing on the wing.
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Thin fiberglass sounds like a good 4th way of sealing the cove. One of the reasons I'm leaning toward 0.8mm ply is the ability to use the product while it's wet. I'll clamp the wet ply in the cove and when dry it should glue in with minimal distortion.
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As always there are many ways to skin the cat, and to do the math..
Dan, I can't get my numbers to match yours but, I will say I can calculate alum stock weighing 15% more per square inch. so a piece of stock 3" x 60" will weigh 2.16 oz in 1/32 3ply birch and 2.52 oz in alum coil stock (.36 oz total for mass difference per side. Both will not float in mid-air so to heavy to the purist (mini Max had NONE) This is not per square inch but for the whole mass.
Here is the problem that I had, was that to span 1/32" birch, I needed stiffeners top and bottom for backing, between each rib, and like you said, I need either varnish or epoxy, I gain the stiffness by getting the bend in the Alum.
And the glass guys can make the part to... Where there is a will there is a way.... I am sure we will hear one or two more ways, all of which can work. Some better than others, some lighter than others..but in the end, all probably will work for this non structural part.
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I come up the same as you did on the ply, but you did not give a thickness on the aluminum...
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I come up the same as you did on the ply, but you did not give a thickness on the aluminum...
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I come up the same as you did on the ply, but you did not give a thickness on the aluminum...
Around here we have some at .010 and some at .0092 I used the latter for calculations.
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As always there are many ways to skin the cat, and to do the math..
Dan, I can't get my numbers to match yours but...
Scott,
Thanks for the fact check. I have edited my other post.
I have made a terrible mistake... Yesterday, somehow I came out with a 1 inch cube of plywood weighing .0244 lbs.
Today, I put pen to paper and kept up with the units, and I must have divided something yesterday when I should have multiplied --but today that same cube came out weighing .495 lbs (8 OUNCES)
It takes a long time to do it but I will show my work this time with an equation editor I ran across that lays it out nice and neat, so I will put it in another post...
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Scott,
Thanks for the fact check. I have edited my other post.
I have made a terrible mistake... Yesterday, somehow I came out with a 1 inch cube of plywood weighing .0244 lbs.
Today, I put pen to paper and kept up with the units, and I must have divided something yesterday when I should have multiplied --but today that same cube came out weighing .495 lbs (8 OUNCES)
Ok, I think I have it correct this time... I woke up a little foggy yesterday I guess. I think where I went wrong was 4.5 cubic inches of the plywood weighed .11 lbs.
So this time I came out with 5 feet of the metal weighing 2.6 ounces and 5 feet of the ply weighing 2.2 ounces.
If you are going to make a decision based on these calculations, I suggest you check my work... See attached.
The equation editor takes so long it becomes a strong potential for errors.
Thanks again Scott.
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I think this is going to work: Only had access to a 36" brake, precluding installing the flashing in 2 pieces. So, installed three pieces with a 30" section inboard, a 32.5" section outboard, and a 15 3/4" section spanning those two in the middle, (1/16" wider to account for the overlap). As Scott thought, installing multiple pieces made it easier to install and the shorter sections allowed for any small imperfections in the wood structure beneath or the metal itself. Installing all 3 pieces took less time and effort than the single, 6 1/2 foot long piece I originally tried.
Thanks for all the ideas and help with this!
Eagle on!
Rick
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Note to anyone trying this method: To save tons of time and sweat, rough up the surfaces to be glued BEFORE you bend the metal while it's still flat and accessible. Not that I would make such a mistake. I just have a "friend" who did that. Yeah. A "friend".
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Looking real good - congrats on getting that to work.
+1 on the roughing up the surface before bending - I found that out the hard way also.
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Hi guys,
The thought of wrestling with the aluminum didn’t seem like an option for me. I went with fiberglass cloth and west system epoxy. I don’t have a scale so I can’t give accurate weights. I started with 3” pvc pipe and applied duct tape, 4layers with clear packing tape as the final layer for release. The tape was to increase the diameter of the pipe mold to match the wing. The wooden strips for the edges are lumber yard 8061 moldings. The radius wasn’t quite the same so I altered it a bit. Set up a jig in the drill press and drilled 1/2” holes every 1”. The 3/8 x #6 screws were removed after epoxy dried. The parts felt very light in my hands, and for me was very easy to accomplish.
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More pics
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That looks good to - not sure which is more time consuming - your method or the aluminum one :)
Now if we could to that but with a mold that had a flange well that would be really cool!
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That looks good to - not sure which is more time consuming - your method or the aluminum one :)
Now if we could to that but with a mold that had a flange well that would be really cool!
Love to see the great new ideas coming along, one might note that what really works well in many cases, is that where the screws go as seen in the photos, I have used 3/32 alum rivets to hold, until the bonding material is fully cured. With the air-riveter it certainly takes longer to drill the hole than it does to install the rivet. But the second beauty is that we can use cleco's before hand and make sure all holes and every hole work.
Yes, we have used the rivet, to extend through the wood piece, or into it.
Then remove glass/piece, apply bonding material to prepared surface (3M-2216) pop in the rivets, wipe excess, and onward. These rivets in essence really become "tear" rivets If the bonding ever lets loose, we got a lot worse things starting to happen, and by then it won't matter much.
This is a weight and speed to install thing, certainly not bashing screws...
Keep up the good work guys and best of success!
Scott :))
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Really love seeing all the ways problems get solved here! Nice looking set up.
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Mark Kramer: The fiberglass looks very nice. What weight fiberglass cloth did you use and how many layers?
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Hi,
Bought the fiberglass at Lowe’s. 8sq ft for car bodywork I think. There was no weight given on the package. I have boat building history and think maybe 6 oz. You can get 1.5 oz from ACSS. I don’t like their prices and shipping prices, so I went with Lowe’s aircraft supply.The layup is two layers thick. I kept a 1” piece I cut off one end, and also a 1” piece of the wood edging pieces with a lightening hole in it. I plan on weighing them as soon as I get access to a scale. Should be able to get a fairly accurate weight of the airleron well. By the way, it’s incredibly strong.
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Thank you for the info. I think I have enough 4 oz or 6 oz fiberglass to give it a try.
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I had some black duct tape that seemed thicker than the grey stuff, and ran 4 layers lengthwise with a layer of clear packing tape which worked well for a release. I made it longer and wider than needed, then after measuring snapped chalk lines and cut it before installing with a dremel and small metal cutting wheel. I then epoxied it in before adding wood edges. In this case of glueing I precoated both surfaces with plain epoxy, then added a little thickening agent to insure a complete bond. In my case the sticks at all the edges may be a little over done, something a little smaller might be better. They just have to be nice and straight and in plane with the wing surface, and strong enough to carry fabric loads. The thickening agent I used is west system number 403 micro fibers.
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I read this post completely twice, i havent built mine yet, although i have a friend w/metal fab shop, i will likly use .08mm ply.
I have glued the K-blocks into the ribs already(mod in jig). I sanded them while ribs in a stack(if ever there was a place for laser cut parts, this one yes) planning to build as much of aileron as possible before cutting free of ribs. keeping clearance at 8mm.
Wood is easily sanded to .010 also resilient, toothpicks make great shims.