On Sat, 14 Aug 2004 23:45:17 GMT, Guy Alcala
wrote:

John Carrier wrote:

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

H'mm, those numbers seem kind of high for both, as far as sustained
capability
goes.

400 KTAS, turn rate in Deg./sec. (rounded off) = 19 (7g); 22 (8g).

500KTAS, turn rate in Deg./sec. (rounded off) = 15 (7g); 17 (8g); 20 (9g).

600KTAS, turn rate in Deg./sec. (rounded off) = 13(7g); 14 (8g); 16 (9g).

I'm missing something here. You say the numbers are high and then offer
higher numbers. Or are these just basic computations of turn rates w/o
regard to airframe factors?

snip

Yes. I wanted to show what the maximum turn rate was for the various KTAS/g
combinations; sustained would be less.

Guy

I woke in the middle of the night thinking about this discussion--I
know, it indicates some level of neuroses....

I've said that KIAS not True Air Speed is the relevant number, you
indicate a desire to relate G available and hence turning performance
to KTAS.

Consider this. At low altitude, true air speed can be quite close to
indicated. It will always be higher than indicated, but not
exceptionally higher. So, if you are running around at corner velocity
(always expressed in KIAS) of say 420 KIAS, you might be at 475 KTAS
and you could pull max allowable G.

Now, move the airplane up to FL450 and establish the same 475 KTAS
condition. Ooopps! You're cruising around at something less than 300
KIAS (don't dissect the number, it's an approximation but reasonable).
You only have aerodynamic capability to pull about 3.5 G.

But, you've got the same KTAS. The point is that True Air Speed
doesn't consistently offer aerodynamic performance. It's those little
molecules doing their Bernoulli thing over the wing surface that makes
it happen--KIAS!


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
"Phantom Flights, Bangkok Nights"
Both from Smithsonian Books
***www.thunderchief.org