FrankS said:
I think Van must have been playing around with some idea on this wing. I have seen earlier photos where the flaperon was clearly a constant chord the whole length. Now it clearly has a step in the chord midspan. Was he trying to boost the aileron power?
Hey, who among our RV-12 enthusiests is going to be our Oshkosh reporter to get us the inside story in a couple of weeks? I can't make it this year.
Hi Frank,
I don't think he was trying to boost aileron power...
Read my post a couple above, I think he was trying to generate more lift inboard. The easy (non elegant) way to do that without redoing the entire wing is the shorten the cord of the wing (Leading Edge to Trailing Edge Distance) in this case justs shorten the control surface width. We know he was not happy with the stall and airflow in that region close to the stall. I know I would do that first before redoing the wing...
In a nutshell a shorter cord, same thickness wing generates more lift, than a longer cord. You can simply (non elegantly) change the cord by changing the control surface width. If that does not help you will have to change the wing profile, and the entire wing. "Thicker" wings relative to their cord generally makes more lift, up to a point, then it is not a wing any more...
Proof in case from my RC plane design days I designed and build combat flying wings out of alternative materials. I am not an expert just a DIY aerodynamic guy, and if you just look at flying wings, you can sense these things are very sensitive since they do not have horizontal stab. If set up right they turn on a dial in pitch, cause there is no horizontal stab back there to drag around. But there-in lies a problem as well, if the wing start to stall and drop a wingtip things go bad, fast, into a spin. The easy way to ensure that you keep control of the flying wing when it stall is to ensure the wingtips stall last. The easy way to do that is cut the ailerons at a taper hence shortening the cord of the wing vs thickness of the rest of the wing. That means the tips will keep flying while the mid portion of the wing starts to stall and the plane just nose down build speed and flies on. The other way around and you have spectacular effects especially on a flying wing.
The picture below shows clearly the ailerons cut to a taper at the end. Without it the plane can not turn as tight in a controlled fashion. The wing is a double taper wing, but the chord vs thickness ratio stays the same, i.e. almost like a RV bar wing (almost for the layman's aerodynamics). Except for the wing tips where the relative thickness ratio increase and produce more lift, and less stall compared to the main wing. The design and plans are on my website, contact me via email if you guys want more info on this RC model.
I hope all that was worth-while...
Well at least watch and enjoy the video of it if you don't understand a thing I wrote above and see how controllable this thing was
http://www.rudigreyling.com/rc%20movies/draco_640x480x30fps_8.5mb_500kbs.wmv
Kind Regards
Rudi