On Thu, 24 Apr 2008 12:46:29 GMT, Jay Maynard
wrote in
:

On 2008-04-24, WingFlaps wrote:
When will pilots learn to stop trying to do the impossible turn... and
go for a straight ahead landing on soemthing horizontal?

Depends on what you mean by "the impossible turn". If you mean turning back
at 200 AGL, yeah, that one's pretty much impossible. If you mean 600 AGL,
it's pretty much possible in the average aircraft. (Hell, that's pattern
altitude at EFD!) The line lies somewhere in between.

This subject has been discussed in detail with the assistance of
erudite professor Lowry's input:
http://groups.google.com/group/rec.a...1d80a2e846a88b


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

Nov 1 1999, 1:00 am
Newsgroups: rec.aviation.piloting, rec.aviation.student
From: "John T. Lowry"
Date: 1999/11/01
Subject: Turn Back Maneuver


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





Mo
http://groups.google.com/group/rec.a...4829291b24775f
http://groups.google.com/group/rec.a...c37fab40401aba
http://groups.google.com/group/rec.a...73917967e58181
http://groups.google.com/group/rec.a...b42a74fe660741
http://groups.google.com/group/rec.a...73917967e58181
http://groups.google.com/groups/sear...X-Y_&filter=0&
http://groups.google.com/group/rec.a...095b7459a04b3a