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Old Jun 05, 2012, 10:54 PM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
1,086 Posts
Mini-HowTo
hotwire-free aerofoil flying wing =)

i have been recently doing a lot of stuff with non-hotwire wings. my first two attempts (which some of you may have seen/laughed at) were pretty crappy. i used a simple, "knife-hewn" leading edge on a kf aerofoil. this one, however, is a different story. i used one of those "cheese grater" things that they use for carving wood. (link at bottom) to carve out the shape, and covered it with tape. it turned out very well. so far i have only done the right wing, but because of my weird finals schedule i have the day off tomorrow, so i will try to finish it up then. i will post pictures tomorrow too.

http://www.google.com/imgres?um=1&hl...9,r:1,s:0,i:74
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Old Jun 06, 2012, 12:48 AM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
1,086 Posts
update: right wing tape-up is done. it turned out really good. very light, and as stiff as any wing i have seen (and stiffer than a lot of them) aerofoil is semi-symmetrical, and very thin (1/2 inch thick wing) so it should go pretty fast. dimensions: ws=48", root chord=12", tip chord=8", sweep=4"
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Old Jun 06, 2012, 02:10 AM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
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Interesting. I like that cheese-grater thing a lot
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Old Jun 06, 2012, 11:26 AM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
1,086 Posts
ta-da! pics are done.
order (right to left): top view of the right wing, side view of wing root, side view of tip, close-up of surface (it looks rough, but it is tape covered so it doesn't have any affect. you could sand it if you wanted.
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Old Jun 06, 2012, 03:47 PM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
1,086 Posts
SHE'S DONE!! (mostly)

that didn't take long, did it? anyway, she is all taped up, with fins, servos, elevons, hatch, and batt all set up. auw (without control linkages yet) is only 350 grams. that's with battery! not bad for a 48" sloper eh? anyway, finished product pic is below, and i will be posting a build video on youtube soon too.
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Old Jun 06, 2012, 03:59 PM
I used to like trees
rchank's Avatar
United States, WA, Spokane
Joined Jul 2011
288 Posts
Sounds like you used a Surform rasp. They are a good tool for rough shaping of foam.
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Old Jun 06, 2012, 09:08 PM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
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Quote:
Originally Posted by rchank View Post
Sounds like you used a Surform rasp. They are a good tool for rough shaping of foam.
RASP! i knew it was something like that =) slope testing will begin this weekend.
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Old Jul 15, 2012, 12:40 AM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
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sorry for the big delay guys, i put this wing away for a while. anyway, here are the updates: slope went pretty badly (only worked in very light winds) so i motorized it. using a cheap, bell type motor from a hobbyking cessna, 20 amp esc, and a 6.5x4 folding prop. she flies BEAUTIFULLY!!!! tons of float, great speed range, extremely aerobatic. on a cheap motor drawing about 240 watts, i was able to hit 65mph (used doppler to check speed) it is also very durable. there were a bunch of kids and their parents watching, and one of them asked if it was homemade. i turned to say yes, and just looked back at the plane in time to see it smack into the ground at 40mph. (i have a habit of not trimming planes) however, the only damage was a couple of little wrinkle-lines in the nose, and a broken control horn. it was up and flying again within 10 minutes.
things i have found with this plane:
seems like flying wings work much better with a thin aerofoil.
pink foam CAN be durable, as long as you do a good job with the tape covering.
hotwires are not necessary!!

i'll try to get some flight video up tomorrow.
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Old Jul 15, 2012, 12:53 AM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
12,444 Posts
If you get tired of the messy cutting the rasp does, I highly recommend Master Airscrew's razor plane. It's a little device with a sharp blade that can be adjusted to make precise depth-controlled thin cuts in balsa and foam. It makes extremely quick work of pink foam in particular, which seems to respond well to carving.

As for tape strengthening pink foam, I couldn't agree more. I never used to do it, but awhile ago I built a new pink wing and coated it with a layer of colored duct tape on each side just to keep the foam from building up the dirt, grime, grass stains, and fingernail marks that it gets when it's bare. That wing later survived a 50++mph impact with a bunch of cartwheels and a 10' bounce. I was impressed I never used to believe such stories and just chalked it up to exaggeration, but I no longer have any doubts.
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Old Jul 15, 2012, 01:02 AM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
1,086 Posts
Quote:
Originally Posted by C₄H₁₀ View Post
If you get tired of the messy cutting the rasp does, I highly recommend Master Airscrew's razor plane. It's a little device with a sharp blade that can be adjusted to make precise depth-controlled thin cuts in balsa and foam. It makes extremely quick work of pink foam in particular, which seems to respond well to carving.

As for tape strengthening pink foam, I couldn't agree more. I never used to do it, but awhile ago I built a new pink wing and coated it with a layer of colored duct tape on each side just to keep the foam from building up the dirt, grime, grass stains, and fingernail marks that it gets when it's bare. That wing later survived a 50++mph impact with a bunch of cartwheels and a 10' bounce. I was impressed I never used to believe such stories and just chalked it up to exaggeration, but I no longer have any doubts.
yup. i usually use clear/clear-ish tape so i can see if the foam has broken when i crash.
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Old Jul 15, 2012, 01:04 AM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
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Quote:
Originally Posted by C₄H₁₀ View Post
If you get tired of the messy cutting the rasp does, I highly recommend Master Airscrew's razor plane. It's a little device with a sharp blade that can be adjusted to make precise depth-controlled thin cuts in balsa and foam. It makes extremely quick work of pink foam in particular, which seems to respond well to carving.

As for tape strengthening pink foam, I couldn't agree more. I never used to do it, but awhile ago I built a new pink wing and coated it with a layer of colored duct tape on each side just to keep the foam from building up the dirt, grime, grass stains, and fingernail marks that it gets when it's bare. That wing later survived a 50++mph impact with a bunch of cartwheels and a 10' bounce. I was impressed I never used to believe such stories and just chalked it up to exaggeration, but I no longer have any doubts.
i've used a razor plane before, and i still prefer the rasp. yes, it is messy, but i find the razor plane tends to make a sort of "ridged" shape with a bunch of flat spots.
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Old Jul 15, 2012, 01:41 AM
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Stupot46's Avatar
Joined Sep 2011
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It used to be possible to get a longer version of the surform,about 12" IIRC.Might make it easier to get an even cut.
Stuart
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Old Jul 15, 2012, 02:52 PM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
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Quote:
Originally Posted by Stupot46 View Post
It used to be possible to get a longer version of the surform,about 12" IIRC.Might make it easier to get an even cut.
Stuart
that's what i have. it's yellow and grey, about 1 foot long and 1.5" wide. going to get some flight video today.
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Old Jul 25, 2012, 06:47 AM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,501 Posts
Might try a perma grit bar sander, its very agressive on one side while the other is good to finish up.
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Old Jul 25, 2012, 10:05 PM
cheapskate extroardinairé
United States, CA, Marin
Joined Jul 2011
1,086 Posts
Quote:
Originally Posted by ApexAero View Post
Might try a perma grit bar sander, its very agressive on one side while the other is good to finish up.
but i already have a rasp, which works perfectly fine. i can always just epoxy my fine sanding stone on the back =P
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