Mailing List lml@lancaironline.net Message #16259
From: James Frantz <LFrantz@compuserve.com>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Best Glide
Date: Fri, 15 Nov 2002 00:04:01 -0500
To: <lml>
>It seems the less the angle of attack, the farther you can go in glide.
I'd
guess that increasing angle of attack increases drag, which bleeds off
energy,
which means you're going to hit the ground earlier.<

In 1 "g" flight the faster we go the higher the parasitic drag and the
lower the induced drag.  In 1 "g" flight the slower we go the lower the
parisitic drag and the higher the induced drag.   The best glide AOA and
IAS occurs where the sum of the parisitic and induced drag are at a minimum
(the bottom of the bucket curve). The best glide occurs at a specific AOA
(about 6.5 degrees for the 360 as I recall) and flying at a higher AOA
(lower IAS) or flying at a lower AOA (higher IAS) will both result in less
glide.

The nice thing about AOA is that it automatically self compensates for GW,
CG, bank angle and everything else.  IAS is not self compensating.  In
other words, for the L-360, you can fly at 6.5 degrees AOA and be assured
of the gest glide. But flying at the best glide IAS, say 105 knots per the
book, will not assure you of the best glide.  The IAS meter just got us in
the ball park.  The difference in best glide IAS comparing a heavy vs.
light GW is about 13%, a 60 degree bank turn vs. straight land level is 41%
and so on, while the best glide AOA is always the same number for your
aircraft.

James B. Frantz
Proprietary Software Systems, Inc.
www.angle-of-attack.com
LFrantz@compuserve.com
(952) 474-4154
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