|Sep 12, 2012, 06:28 PM|
Joined Aug 2011
I have been working on a forward swept EPP finless wing for a week or so and finally after the third version I got a successful flight.
The photos show how I constructed the first version and then I had to modify it by lengthening the nose to get the CG out where it is supposed to be.
This Wing CG Calculator, http://wingcgcalc.bruder.com.br/en_US/ helped me a lot because it allows multiple wing panels and negative sweep. I couldn't believe how far forward the CG had to be placed.
Motor: 1800kv (I think) and 8*6 prop
WSpan: 1 meter
material: 9mm EPP that has been laminated with copy shop laminate (very strong)
The video is unedited and taken at 5 am (haven't reset the clock in the video) - had to fly before the campus students woke up and started milling around.
Haven't flown it enough to get a feel for flight characteristics but it seems pretty stable - wind was blowing a bit and it doesn't waggle like my conventional finless wings.
Update: 9/14: flies nice in no wind, waggles in wind. Going to try dihedral.
Update: 9/15 Raised wings 6 degrees and flew in calm air- made wing rock worse and controls more sluggish. One advantage - very stall proof. To do: move cg forward a bit, then try fin,then try negative dihedral.
Frustrating: took dihedral back out and evidently the repair glue has moved the cg back so now won't fly. Putting more ballast up front and also thought of straightening wing tip angle as a gust probably catches the end of the wing since the tip is pointed inwards and pushes harder than if the wingtip had no angle or even was angled out a bit. Thats my next trial. Fortunately this EPP is tough stuff as I'm crashing a lot now and no damage so it seems I can keep on crashing.
Terrible, up to 660 grams now with glue on the back end and dead weights on the front. Not sure if big fat front end is messing up the aerodynamics. It is a real floater when the power is off but seems to burn up the battery pretty quick to stay aloft.
Doesn't seem to be anyway to control yaw without a fin but I dislike that solution. Did find that right elevon was quarter inch wider than left but that would only affect roll I think, not yaw. Maybe what I'm seeing is roll instability and not so much yaw.
Update: 9/16 Flight at 4:45am and it was great. I added more ballast (a hefty 680grams now) and trimmed the right elevon to be the same size as the left. Slow ponderous lift out but pretty when up to speed. Definitely underpowered now. Feels like a bomber. No fins.
Update: 9/18 Beautiful flight this morning. Even flies smoothly through a little wind and really gets going downwing. Flies more like a scale model but still has pretty fast rolls. Could probably do with even a little larger elevons.
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|Oct 29, 2012, 06:16 PM|
Finless FSwEPP Wing
Still catching up on the blogs and probably have another 50 pages to go before I start seeing familiar posts. As you probably already know, I really like this design.
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