Turn Back Maneuver

[John T. Lowry]

Best turnaround bank angle phi (least altitude loss per angle turned
through) for a gliding airplane is given by:

cos(phi) = (sqrt(2)/2)*sqrt(1-k^2)

where k = CD0/CLmax + CLmax/(pi*e*A)

where CD0 is the parasite drag coefficient, CLmax is the maximum lift
coefficient for the airplane's flaps configuration, e is the airplane
efficiency factor, and A is the wing aspect ratio. I know most ng readers
hate those darned formulas, but that's the way the world works.

For GA propeller-driven airplanes, k is a small number (0.116 for a Cessna
172, flaps up) and so the best turnaround bank angle is very closely the 45
degrees cited by Rogers and, much earlier, by Langewiesche (Stick and
Rudder, p. 358). For the above Cessna, for instance, it's 45.4 degrees. For
a flamed-out jet fighter, however, things are considerably different.

The formulas above, along with formulas for the banked stall speed, for
banked gliding flight path angle, and for the minimum altitude loss in a
180-degree turn, can all be found in my recent book Performance of Light
Aircraft, pp. 294-296. The following seven pages then treat the
return-to-airport maneuver, from start of the takeoff roll to contact with
the runway or terrain, in excruciating detail. Including wind effects, the
typical four-second hesitation when the engine stops, etc.

John.
--
John T. Lowry, PhD
Flight Physics; Box 20919; Billings MT 59104
Voice: 406-248-2606

[Ron Rosenfeld]

Thank you for posting that.

Best,
ron
John T. Lowry <jlo...@mcn.net> wrote in message
news:s1r7s5...@corp.supernews.com...