Effects of Altitude on Required Coefficient of Lift

[thorsim]

i thought ...

IAS was a measure of force of the air and relates to stress loads, lift, and in this case turn performance at relative altitudes.

 i.e. speed limits related to forces  ...

 and ...

TAS is a measure of speed of the air and relates to airflow over the surfaces and how the surfaces and the air relates at different speeds.

i.e. speed limits relating to the ability for the air to flow "cleanly" over the surface of the aircraft. 

that being the case i am unclear how TAS would be a determining factor of turn rate at altitude unless you guys are saying compression is coming into play ...

Stoney, I think I figured out how this works way back in our discussion about IAS vs TAS in P47 glide numbers.

Physics wise, the IAS speed will dictate how much lift the wing can generate. TAS is irrelevant for lift considerations if you have IAS available.

What TAS DOES affect though is your turn radius. You will pull a MUCH wider turn radius at high altitude for the same amount of Gs (i.e., lift).

[FLS]

For a guy with a lot of opinions about flight modeling you seem to lack some very basic information. No offense.   

IAS is an air pressure measurement. IAS is how fast the wing thinks you're flying. TAS is how fast the ground thinks you're flying. When they're apart they disagree but when they come together they agree.

Note that Boomerlu said turn radius not turn rate. Since your True Air Speed is high your turn radius is big but since your Indicated Air Speed is low you are limited in how much G you can pull.

[thorsim]

ahh i see where you are going now ...

but FYI wings don't think

[FLS]

Just to clarify my oversimple explanation, TAS isn't really ground speed because it's affected by wind direction. TAS is literally your true speed through the air.

I think you just got confused by mixing up turn rate with turn radius.

[thorsim]

yea i was in brain fart mode ...

i did not phrase my question well either ...

happens from time to time ...

+S+

t

[boomerlu]

FLS nailed it. When TAS > IAS, same Gs, same turn rate, bigger turn radius as compared to when TAS = IAS.