Why are delta wing designs reputed to lose speed during turns?

On Wed, 24 Sep 2003 14:21:15 -0700, Hobo wrote:



It is commonly said that delta wing designs lose an above average amount
of speed while turning and that this a deficiency of the design. Is this
true, and if why does this occur? Also, how does this reputed flaw
affect the potential performance of the Typhoon?

TIA

Delta wings are typically a low aspect wing (stubby) which requires a
higher angle of attack to generate additionally lift than a higher
aspect (think Long and slim). Higher AOA results in higher drag,
hence one needs more thrust to maintian same speed.

I'm told that the F-106 was famous for it's first bat turn but after
that it was pretty much toast.

Ross "Roscoe" Dillon
USAF Flight Tester
(B-2, F-16, F-15, F-5, T-37, T-38, C-5, QF-106)

Hobo wrote:



It is commonly said that delta wing designs lose an above average amount
of speed while turning and that this a deficiency of the design. Is this
true, and if why does this occur? Also, how does this reputed flaw
affect the potential performance of the Typhoon?
It primarily applies to "pure" deltas, like the Mirage
III and F-102/106.
You don't see this to the same degree in deltas with
tails or moving canards, like the MiG-21, Typhoon, Rafale,
Gripen, etc.
With a pure delta, the elevons act a bit like spoilers
when they are driven up to bring the nose up, so you need a
higher angle of attack for a given lift, and more induced drag.
--
--Matthew Saroff
Rules to live by:
1) To thine own self be true
2) Don't let your mouth write no checks that your butt can't cash
3) Interference in the time stream is forbidden, do not meddle in causality
Check http://www.pobox.com/~msaroff, including The Bad Hair Web Page

You don't see this to the same degree in deltas with
tails or moving canards, like the MiG-21, Typhoon, Rafale,
Gripen, etc.

The Mig-21 would (does?) bleed energy like a big dog at high alpha. A
canard will have a positive impact versus a conventional horizontal tail
because of its lower drag contribution to generate high alpha.

R / John