Planform will affect how a plane turns, but not really in the way you are
thinking. A good planform (close to elliptic lift distribution) will allow
higher angles of attack to be gernerated (tighter turns) without stalling.
Higher AR wings will produce less induced drag (which is the dominate form
of drag in turns), so longer spans are better.
Sweeping the TE vs Leading edge will have very little effect on turning
ability. Cl max decreases as the wing is swept aft, however the difference
in sweep of the 1/4 chord between a straight TE vs LE is very little.
The Zagi, or any typical swept wing foamy use sweep and washout for pitch
stability. Basically the wing tips are functioning as stabs. This design
is very inefficient and will have extra drag especially at high or low
angles of attack. The JW or any non-swept flying wing will have specially
designed low piching moment airfoils so that they do not require sweep or
twist. So in reality it is not so much the planform here, but the
differences in airfoil and twist.
Gavin
-----Original Message-----
From: Mike Bailey [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 24, 2001 10:44 PM
To: rcse
Cc: Mark Drela
Subject: [RCSE] efficent wings for pylon turns
Ok you aeronautical gurus. I have been playing with wing planforms lately
and now I want to discuss this with other people.
I am looking at a wings ability to retain speed/energy through a pylon turn.
Efficiency through a loop would be similar.
First I will start with flying wings. I have a new plane that has a strait
leading edge and a tapered trailing edge. The wing's CG is at about 13% of
mean cord and this may have some thing to do with the performance. This
plane has noticeably better turning efficiency than a swept back flying wing
(zagi). I have also flown a JW and the performance is the same.
For a conventional pylon racer I am wanting to do some more experimenting. I
have a one design racer with a strait trailing edge. I am going to build a
new wing with a strait leading edge and fly them back to back for
comparison.
Lately I have had a discussion with some people about the effect that a
square tip rather than rounded or elliptical tip has on how a plane turns.
Any thoughts here would be appreciated.
The point here is that I would like to better understand how the wing shape
not airfoil affects the drag in this high angle of attack situation.
Please comment,
Mike
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