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Old Jan 23, 2007, 09:27 PM
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USA, ID, Coeur D'Alene
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Question
so i bought this foam...now what?

i was at the local hobby shop last weekend and decided that instead of buying a slightly overpriced kit, id build something instead.
so i bought 2 sheets of 2mm depron an some .050" carbon rod. problem is, i cant find any threads with nice semiscale indoor planes. i want to try my hand at a folded depron wing with a full airfoil. maybe a horten wing for simplicity. i want it to fly with very little power like 4 of gws' smallest motors running direct drive, maybe in the 4-7 oz range.

any suggestions?
Derrik
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Old Jan 23, 2007, 10:35 PM
TheyreComingToTakeMeAway!
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anything at all?
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Old Jan 23, 2007, 10:46 PM
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I'd look around for something you like and scale it down. Be aware flying wings are low in drag and tend to be fast which might not be what you want indoors. Unless it is!
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Old Jan 23, 2007, 10:58 PM
TheyreComingToTakeMeAway!
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yeah they can be fast unless built light which is what im good at. i would just start cutting and see what comes of it but i havent done this kind of construction before so i want something to read up on before i start but, i cant find anything yet.
i have built plenty out of balsa and thicker 6mm depron but they didnt use the folded style building.
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Old Jan 23, 2007, 11:28 PM
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If your looking for ideas on how to fold the wing I have done several in 2mm up to 6mm. Mine dont use ribs or any carbon, just a foam spar.

Details are in the first few posts in this thread along with some additional links.

http://www.rcgroups.com/forums/showt...71#post6352871


If your going to do a Horton with a swept LE you will have to do two halves and join them. Id use .5oz glass cloth and water based Varathane.

Good luck!

Larry
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Old Jan 23, 2007, 11:51 PM
TheyreComingToTakeMeAway!
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glass cloth? i think i could get away with less than that. and as i said before, the flying wing was just an idea since theres not much to it. id be just as happy with a straight wing full fuse twin or quad motor plane. hmm maybe like one of the local fedex twin engine cargo planes.
ive heard that some people put clear tape on the l.e. before folding the wing to keep it from cracking. i tried a small test section of wing and used green masking tape, after it was folded and glued at the t.e. i removed the tape and it looks good but i think it might make for a weaker wing. also as a way of adding area without much weight, i was thinking of letting the top skin go past the bottom about 1 1/2" i think it would help the slow speed lift as well.
what do you think?

Derrik
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Old Jan 24, 2007, 12:18 AM
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Glass cloth to re-inforce the joint

If I went to all the trouble to make a symitrical airfoil, I would leave it that way. If you want to droop the trailing edge - drop flaps

Larry
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Old Jan 24, 2007, 12:29 AM
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well i didnt have symetrical airfoil in mind, flat bottom or close to it was more what im leaning for. and if it was a cargo plane, the drooped t.e. would look great i think. and as for reinforcing, i think a balsa sub spar glued to the depron one would hold well for what im trying here. im not going for aerobatic in any way, just the opposite actually. i want a docile slow flying plane that can rog and looks and flys like a real plane. thats why im leaning twards a flat bottom with drooped t.e. becuse it would have the lift i need for slow flight.
ive ben searching through google images for a mulit motor cargo plane but havent found the right subject just yet. something like the flying boxcar but without the twin booms would be nice.
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Old Jan 24, 2007, 12:51 AM
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Ah - Then you might look thru this thread for a gazillion 3 views. Something in there might just do it for you.

http://www.rcgroups.com/forums/showt...=2#post6735822

Larry
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Old Jan 24, 2007, 01:36 AM
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sweet thread larry, thanks for the link. now i need to go to a proper computer to view them all (all i have atm is my pda phone's internet) from the ones i saw already, i think i could find one :P
actually i may have one right now, the ov-10 bronco. i think at about 24" ws and a target weight of 4-5 oz it would be great in the gym. and not too complicated to build either, nice and straight wing

Derrik
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Old Jan 24, 2007, 04:07 AM
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well i got a 26" wing almost finished i just need to add the sanded tip blocks to finish it. it weighs a litle more than i wanted but has a good airfoil to it (with 1.25" of it single layer drooped) with a total chord of 6". max thickness is 5/8ths" or 16mm at 1 7/8" back from l.e. which if my math is correct, equates to 10% thickness at 31% of total chord
is that a good airfoil with a somewhat sharp l.e.?
next ill start on the center fuselage and see how that goes.
pics to come later

Derrik
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Last edited by derk; Jan 24, 2007 at 04:24 AM.
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Old Jan 24, 2007, 08:11 AM
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after spending the last oh say 2 hours coaxing the depron into a rolled tailboom, it honestly is too much work for what i got. but while staring at the failed boom and scraps around it, i came up with a super easy, light and strong way to make it. basically a sandwich of depron glued onto some eps foam. it has great weight without the need for reinforcing. and by using the depron as only stiffiners, allows you to shape the eps to the desired curve very quickly. i should have both booms finished tomorrow easy. till then i need to sleep, living the at-home night life

Derrik
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Old Jan 24, 2007, 08:21 AM
Time for another motto!
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For slow flight with undercambered wings, the general wisdom is to built a 4-40 wing. 4% thickness at 40% of the chord. It may be different for flatbottom wings, but 10% sonds pretty thick to me. You might need it tough to keep the wings rigid.
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Old Jan 24, 2007, 09:28 AM
TheyreComingToTakeMeAway!
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Jelleb i think it will be ok for what im making. it does feel strong enough but if it were just a single surface undercamber wing, it would want to fold if it ever had any inverted flight attempts. and this wing has the equivelent to rear camber with the extended top surface. the shape, to me, resembles a thermal glider airfoil. good lift for slow flight but pull out the camber and it becomes a rocket. i'll have to go through an airfoil list and see whats the closest to it.
at least the indoor venue we have is rather large (for a gym anyways)

Derrik
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Old Jan 24, 2007, 01:01 PM
Time for another motto!
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let me guess, it looks like a jedelsky profile?
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