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Old Sep 22, 2012, 07:58 AM
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Joined Aug 2011
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New project: X45WL II Finless EPP Wing

X45WL II - Finless EPP Delta Wing (3 min 59 sec)

Previously I had built a wing (X45WL) in dollarstore foam but after a few crashes it wasn't airworthy anymore and so I promised myself I would build one again in EPP foam. Here is its successor in laminated EPP foam, finless, bigger motor with a little larger dimensions and pretty crash resistant.
Although it looks like a stepped wing in fact there is laminate over the exposed spars on the leading edge that makes for a crude airfoil without an actual step.

Material: laminated 9 mm EPP foam
Construction Time: 3 hours
WS: 700 mm
Root Chord: 540 mm
Tip Chord: 80 mm
Sweep: 580 mm
Wing area: 336 sq.in.
Weight: 350 grams
Wing load: 5.29 oz/sq.in. - WCL: 3.5
Motor: 1800kv 7*6 prop
Batt: 1100 mah lipo
Esc: 30 amp

Used this exceptionally great CG calculator and could have gotten a more exact calculation using multiple panels but I was lazy: http://wingcgcalc.bruder.com.br/en_US/

I am really happy with how well it flies (for me anyway) though it is definitely not spin proof (imagine a tail would cure that but I think the spin is funny). Guess I need to learn spin recovery next. The video shows how to land a delta wing like a helicopter.
Attached photo of approximate dimensions.
Update 9/24: Took it out for a flight this morning at 5:00am and it flies different than before, wing rocking. Nothing has changed, except the temperature which is 15 degrees Celsius colder. Looked at the wing and one is warped now. Nice theory anyway.
UKpdate 9/25: After reironing the laminate and putting some weights on it I got most of the wing warp out and it flew beautifully this morning. I can make it go into an inverted flat spin by rolling it too tightly for too long - there is no recovery though, I have tried everything and nothing seems to work - it just floats down like a leaf.
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Last edited by FeiJi; Sep 25, 2012 at 07:17 AM.
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Old Oct 28, 2012, 09:11 AM
Watt Waster
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Joined Oct 2010
1,850 Posts
Finless Wing - Delta

Interesting project. I hope to follow progress and learn a thing or two. Thanks for sharing.
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