> Meanwhile, the conventional wisdom seems to be you can't launch flying wings > as high as conventional tailed designs, assuming identical conditions. The > reason is the high alpha (angle of attack) in a histart or winch launch requires > you to crank in so much up-elevon, you ruin the efficiency of the wing's > airfoil.
This is not really true, certain elements CAN be true, but it isn't the prime reason that causes flying wings to misbehave on a highstart. I have done a lot of experimenting with respect to winch and highstart launching of wings and in my opinion, the main reason for difficulty lies in the fact that there is no tail moment to dampen the sudden high AOA rotation when you let go of the wing. The fact that you aren't throwing it into the launch compounds this condition, so you end up with a wing that is essentially in a flat spin on a horizontal plane. The wing rotates so quickly that it is completely stalled. The same thing happens to a lesser degree with scale ships that have the hook on the bottom of the fuselage which can be over 5" lower than the wing. The fix for the scale ship is to throw it (if possible), mount hooks up near the wings and use a bridal, or let it rise off the ground. None of these are really possible with the wing, BUT there is one thing I found that works well although I would be hesitant to do this with a fragile plane like a Klingberg. I put my thumb in the right stick well so it causes about 1/8" of down elevon relative to it's normal trim. This will vary depending on the plane and you could set it up on a launch preset. When you let the plane go, it wont try to rotate as quickly. You pull your thumb out just about as fast as you can think about it. I would say no more than 1 second after releasing the wing. This give it enough airspeed to actually achieve a laminar flow before it rotates, then they tend to go up very well. You can do a rise off the ground if you put a foam bumper on the end of the line to prop the front of the wing up. If you don't do this, it will drag along the ground for a long way..... Don't ask me why I know about this.......... Mark Mech www.aerofoam.com RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
