mstull
R.I.P.
I'm experimenting with using this dual-wall polycarbonate (Lexan) material as covering and sheeting on my new U/L wings.
http://www.palram.com/Media/Uploads/SUNLITE_En_Leaflet(1).pdf
I had to order the thinnest (4mm) material they make to keep the weight down. Unfortunately, clear is the only color choice in this thickness at this time (even though the on-line catalog advertises it in colors). I was hoping for white.
The material is U/V proof on one side, designed for skylights, signs, greenhouses, and other outdoor uses. I'm using it uncovered on the upper and lower wing surfaces. So I won't have to deal with covering and paint at all. So I'll have see-through wings. It is expensive... but no more than a good Stits Poly Fiber covering job. It weighs about twice as much as Stits covering. But that's reasonable, considering it serves as both covering and sheeting.
I've constantly sought a light weight sheeting material, experimenting with carbon, balsa, aluminum, and thin aircraft plywood. Flexing and supporting this material is a good engineering challenge. The material's manual states a minimum flexing radius of 0.6 meters for the 4 mm thickness I chose... about 2' radius (4' diameter). But that limit is cosmetic. When you bend it much sharper than that, tiny ripples form on the inside of the curve. But you can bend it around a much sharper radius before it collapses into a crease. I'm flexing it around a bar/tube that's right above and behind the leading edge tubing, to get a decent airfoil.
I'm using aluminum rivets and special glue to hold it on the spars. Its edges can be collapsed and heat formed with a clothing iron to create a flange that can be riveted. The flange can even be bent 90* with an iron for wing tip connections. I'm not ready to totally trust glue alone with my life. At the rear spar, I slid little pieces of wood up the "grain" of the material to keep it from being crushed by the pop rivets.
I struggled to get the edges of the sheets to line up with each other evenly. I was able to trim them to meet pretty well horizontally. But I did poorly getting them to line up vertically in the middle of the airfoil. I could probably do a little better on a second attempt. But it was extremely difficult, with my attachment procedure.
I need to point out that I'm not experimenting with this polycarbonate material because it looks cool, or just to be different. My goal was to make an U/L monoplane that has a decent roll rate. So I decided to try spoilerons. But to make spoilerons that come out flush with the airfoil (when not deployed), the wing needed to be sheeted... at least near the spoilerons.
My spoilerons hinge in front, like the ones on Quicksilvers. But they are recessed into the wing. So they only protrude when deployed. They are made of carbon, with 2" chord and 4' span. They are designed to flex/twist when deployed, to make them somewhat progressive.
I'm nowhere close to suggesting that this material is going to work, or be a better solution than more common sheeting and covering materials. I'm not sure how it will age and stay attached, with its rather extreme coefficient of thermal expansion. I'll let y'all know how it goes. Heavier versions might work on faster planes.
I found this high strength, glue to hold it on the spars.
http://www.rplastics.com/weldon10.html
It's about as strong as the material itself. It has tremendous gap filling capability, which is important. It's a reactive, two part glue, that dissolves into the surface of the Lexan just enough to get a strong grip. But it is very hard to work with, and gives off toxic fumes for many hours. If you glue something wrong, there's no way to remove it. So every step is do or die. And it applies in globs, drips, and strings. The glue is white. So the result would be way better with white material. The next size heavier material is available in translucent white, and weighs about 20% more.
One way to make it come out looking nicer, would be to buy 100 industrial syringes. That way you could lay a nice bead, rather than try to smear it on with half a stir stick. It would probably work better too. The way I used and attached the material may not be the only way, or even the best way, to use it. I'll let you know if I find a better way. It would be nice if you could just apply a glue out of a calking gun. I didn't experiment with the different glues that come that way because I doubted one would really stick to both the material and aluminum.
Is it possible to sheet/cover an existing U/L with this material? Maybe on some planes. Would you gain anything other than weight? Probably not. To really take advantage of this material, the wing would need to be specifically designed or modified for it. I'll start attaching photos for you to ponder. I'll steal the cockpit, empennage, engine, and some other parts off my biplane, so I'm not making a whole 'nother plane.
If one of you really wants to try it, I would suggest you wait until this summer to give the material a little time to prove out on my plane. So far, it seems like it will be airworthy. Using the clear material with the drippy, stringy, white glue looks so bad, I'll have to hide the glue lines with colored tape. I'll use yellow tape to match the empennage. With an opaque white material, it might even look good.
Here's some pictures. Each spoileron has 4 bungee returns. But I'll probably only need to use 1 or 2 of them. The bungees are replaceable. It's a 3 piece wing to fit in my trailer. The outer panels are 12.5' long each. The center panel is 5' long, for a total of 30' span. The little center section will stay assembled with the cockpit, engine, and landing gear, and roll up into the trailer as a unit. The blue and green print is a protective plastic that just peels off. My design uses a triangulated king post. Yes, using this material is WAY experimental. But somebody had to try it. Expect the first flight around February 2008. Happy New Year.
http://www.palram.com/Media/Uploads/SUNLITE_En_Leaflet(1).pdf
I had to order the thinnest (4mm) material they make to keep the weight down. Unfortunately, clear is the only color choice in this thickness at this time (even though the on-line catalog advertises it in colors). I was hoping for white.
The material is U/V proof on one side, designed for skylights, signs, greenhouses, and other outdoor uses. I'm using it uncovered on the upper and lower wing surfaces. So I won't have to deal with covering and paint at all. So I'll have see-through wings. It is expensive... but no more than a good Stits Poly Fiber covering job. It weighs about twice as much as Stits covering. But that's reasonable, considering it serves as both covering and sheeting.
I've constantly sought a light weight sheeting material, experimenting with carbon, balsa, aluminum, and thin aircraft plywood. Flexing and supporting this material is a good engineering challenge. The material's manual states a minimum flexing radius of 0.6 meters for the 4 mm thickness I chose... about 2' radius (4' diameter). But that limit is cosmetic. When you bend it much sharper than that, tiny ripples form on the inside of the curve. But you can bend it around a much sharper radius before it collapses into a crease. I'm flexing it around a bar/tube that's right above and behind the leading edge tubing, to get a decent airfoil.
I'm using aluminum rivets and special glue to hold it on the spars. Its edges can be collapsed and heat formed with a clothing iron to create a flange that can be riveted. The flange can even be bent 90* with an iron for wing tip connections. I'm not ready to totally trust glue alone with my life. At the rear spar, I slid little pieces of wood up the "grain" of the material to keep it from being crushed by the pop rivets.
I struggled to get the edges of the sheets to line up with each other evenly. I was able to trim them to meet pretty well horizontally. But I did poorly getting them to line up vertically in the middle of the airfoil. I could probably do a little better on a second attempt. But it was extremely difficult, with my attachment procedure.
I need to point out that I'm not experimenting with this polycarbonate material because it looks cool, or just to be different. My goal was to make an U/L monoplane that has a decent roll rate. So I decided to try spoilerons. But to make spoilerons that come out flush with the airfoil (when not deployed), the wing needed to be sheeted... at least near the spoilerons.
My spoilerons hinge in front, like the ones on Quicksilvers. But they are recessed into the wing. So they only protrude when deployed. They are made of carbon, with 2" chord and 4' span. They are designed to flex/twist when deployed, to make them somewhat progressive.
I'm nowhere close to suggesting that this material is going to work, or be a better solution than more common sheeting and covering materials. I'm not sure how it will age and stay attached, with its rather extreme coefficient of thermal expansion. I'll let y'all know how it goes. Heavier versions might work on faster planes.
I found this high strength, glue to hold it on the spars.
http://www.rplastics.com/weldon10.html
It's about as strong as the material itself. It has tremendous gap filling capability, which is important. It's a reactive, two part glue, that dissolves into the surface of the Lexan just enough to get a strong grip. But it is very hard to work with, and gives off toxic fumes for many hours. If you glue something wrong, there's no way to remove it. So every step is do or die. And it applies in globs, drips, and strings. The glue is white. So the result would be way better with white material. The next size heavier material is available in translucent white, and weighs about 20% more.
One way to make it come out looking nicer, would be to buy 100 industrial syringes. That way you could lay a nice bead, rather than try to smear it on with half a stir stick. It would probably work better too. The way I used and attached the material may not be the only way, or even the best way, to use it. I'll let you know if I find a better way. It would be nice if you could just apply a glue out of a calking gun. I didn't experiment with the different glues that come that way because I doubted one would really stick to both the material and aluminum.
Is it possible to sheet/cover an existing U/L with this material? Maybe on some planes. Would you gain anything other than weight? Probably not. To really take advantage of this material, the wing would need to be specifically designed or modified for it. I'll start attaching photos for you to ponder. I'll steal the cockpit, empennage, engine, and some other parts off my biplane, so I'm not making a whole 'nother plane.
If one of you really wants to try it, I would suggest you wait until this summer to give the material a little time to prove out on my plane. So far, it seems like it will be airworthy. Using the clear material with the drippy, stringy, white glue looks so bad, I'll have to hide the glue lines with colored tape. I'll use yellow tape to match the empennage. With an opaque white material, it might even look good.
Here's some pictures. Each spoileron has 4 bungee returns. But I'll probably only need to use 1 or 2 of them. The bungees are replaceable. It's a 3 piece wing to fit in my trailer. The outer panels are 12.5' long each. The center panel is 5' long, for a total of 30' span. The little center section will stay assembled with the cockpit, engine, and landing gear, and roll up into the trailer as a unit. The blue and green print is a protective plastic that just peels off. My design uses a triangulated king post. Yes, using this material is WAY experimental. But somebody had to try it. Expect the first flight around February 2008. Happy New Year.
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