Flying wing version 2 maiden & crash but no flutter
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- Опубликовано: 20 авг 2024
- Watch part one, of this project • Designing and building...
My first wing flew okay but it was too thin and wobbly, so it fluttered quite a lot. People suggested that I should cover foam wing cores with packing paper and PVA glue, so I did. I shortened the wing by 20cm just in case, although it wasn't necessary. The wing came out much stronger that version 1. I got to fly it around 4:30 minutes before I crashed into my friends quadcopter...sorry, so I didn't quite get the hang of its characteristic. I'll fly it again when I get it fixed.
Aerial footage by: / @villehammar3166
Ground footage by: / timpska
Dimensions:
Span: 1000mm
Root chord: 150mm
Tip chord: 115mm
Winglets: 80mm high
Sweep angle: 30º
Electronics:
Cobra 1960kv
5030 x three blade prop
800mAh 3S battery
12A Blue series ESC
2x 4.3g HD-1440a servos
XFLR5
www.xflr5.com/x...
"Odyssey" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
creativecommons...
Quads are for crashing other folks planes. I was thinking that with all the stuff out in the breeze at the center of the wing it won't show its designed efficiency. I've been designing these since I was ten (so about sixty-one years) and the design tend to dovetail around the 25 degree sweep and progressive airfoil from CM 0 (plus but generally slight) and three to five degrees washout. These planes are very easy on power requirements and maneuverable beyond normal expectations. I have had no flutter issues but generally build up the wings. Nice videos on the wing.
My 2 meters flying with swept angle 22 degrees, is my swept angle too small? Never fly before still building the remote control.
Many people on the internet say 25 degrees is "optimal" (for what purpose I don't know) Also aerodynamicists say, swept wing are good only for flying really fast (transonic). High sweep angle moves CG back, which in some cases helps to balance the wing. With 22 degree angle you will probably have to put as much weight in front as possible. My guess is, lower angle wing will be more efficient, but higher angle wing, will definitely look faster and cooler :)
i dont no if you read this. but i have to make a glider for school but i dont now where to start do you have tips for me?
max dimensions: 800mm span, rootchord 150mm
I would say it depends on what tools and materials you have available. If you have a hot wire cutter you cant cut wing cores from foam, like I did. Or you can build your wing from Depron, this material is easier to work with and requires less tools. Check out FliteTest and ExperimentalAirlines channels for depron building techniques.
If you are making a hand launched glider, it will be easier to make a conventional plane with tail. Flying wings are quite sensitive to pitching moment (longitudal stability), it's going to be hard to make a hand launched flying wing glider, that flies (at all) well on the first try. So if your time and resources are limited go for conventional planform: wing, fuselage and tail, make it from depron and use dihedral angle on the wing. Good luck!
Thanks!
How to make material?
how do u cut the suface controls ? what kind of hinges did u use? thnx
+johan corredor I cut elevons from the bottom side of the wing, not cutting through the upper paper surface, leaving it a hinge. Then I added one strip of packing tape on top surface, just in case. The control horns are 1.5mm veneer stuck through elevon and glued with a drop of epoxy on both sides. Nothing fancy, everything is as simple as possible.
thnx man!!! i made a full balsa delta wing (2m span), flew very well, very stable, but i would like a foam balsa wing... nice video!!
how do you cut with hot wire? Make a video on that?
+Tarik Agcayazi (Killsranq) Yes, it's a basic hotwire setup. I use 2 airoil templates (root and tip) made of 4mm plywood. The cutter itself is a wooden bow with nichrome wire, controlled with lightswitch dimmer. Nichrome wire expands quite a lot when heated, so you to keep it tight all the time. I don't have any videosof my hotwire, but youtube is full of them.
+Antti Vainik I use the same setup as you, but my results always come off really choppy and unprofessional, never smooth. did you have any experience with this? also, I try to rush the nichrome wire, so it kind of "bows" when I'm cutting the wing. should I not be doing that, and should I keep the whole wire straight even if it means going slow?
+Tarik Agcayazi (Killsranq) Sounds familiar, I've had same problems. It's a tricky technique, when done by hand. You can't get it perfect but you can sand off small mistakes, and trim the edges.
For me good speed is around 1-2cm per second. Of course speed depends on wings planform. If wing is tapered, you have to go faster at root side and slower at tip. Also temperature is pretty important. If wire burns wood, it's too hot. To prevent bowing I pull the wire tight with fingers, and try to keep it at same tension the whole way, again tricky. In my experience, temperature and tension differences create wavy surface.
You probably already noticed that, bowing can distort the shape of airfoil pretty badly. To avoid that I start cutting from the leading edge and go towards trailing edge, bottom and top separately (don't even try going around in one go). Here's a trick that helps getting better edges: place aifroil template L.E. 5mm away from foam blocks front edge, and leave plenty of spare space for T.E. After wire crosses T.E. don't rush and cut through too fast, just maintain the same speed. This is very important if you want to get a good T.E.
Here's a quick drawing imgur.com/ff9A6z9
Quick question: why the phoenix airfoil? Have you tested MH60 and EH 2/12? just curious, i'm just jumping into airfoils
anyways, I'll try tightening the string and going slower the next time I cut the airfoil. I cut the last airfoil in about 4 tries (top to half, half to end, bottom to half, half to end), so I think i'll try going all the way through (top and bottom separate, like you said) for a smoother cut next time as well.
Also, how do you prepare your templates? Do you laser cut them out with plywood?
Thanks! You're a good teacher. I learned XFLR5 from you too :P
Tarik Agcayazi I read about Phoenix in a paper which said that it's very efficient. It suites well for planks, but not for slow flying swept wings. My first wing had negative pitching moment because of that. I haven't teststd MH or EH series, even though they are popular....I just had to prove myself wrong by picking some unpopular airfoil ;)
For slow flying wing google for PW75 airfoil (and PW51). I also have one project coming up that uses HS520 and HS522 combination.
Thank you for your comments and best of luck :)