Poll: stall speed in a jet at cruise altitude

E_Dawg

E_Dawg

Moderator
With respect to indicated airspeed, will a jet stall at the same, lower, or higher indicated airspeed than it would at a lower altitude?

Anonymous poll
 
Seggy said:
Who cares? :)
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Very important because lots of training departments don't teach this stuff. There is both a high- and a low-speed buffet margin that can really "ruin your day" if you don't have an understanding of where they are.
 
coffin corner!!! Not to be confused with the "turn your head and coffin corner" which is an unfortunate day in the doctor's office.
 
Doug Taylor said:
Very important because lots of training departments don't teach this stuff. There is both a high- and a low-speed buffet margin that can really "ruin your day" if you don't have an understanding of where they are.
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I think there's a pretty severe training gap whereby you can go get all your ratings in pistons, maybe get some hands on time with a turboprop (or not), then find yourself in jet groundschool - where they teach you all about the airplane but not about the environment the airplane is operated in.
 
Chris_Ford said:
coffin corner!!! Not to be confused with the "turn your head and coffin corner" which is an unfortunate day in the doctor's office.
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Exactly.

I had the luxury of being a plumber on a 727 where whenever ATC asked for a specific speed reduction or if we could accept a particular altitude, I'd have to drag out the ODM to determine how fast, how slow, how high and "when".
 
No no no. :D

A combination of altitude and airspeed from which it would be impossible to successfully complete an autorotation in the event of an engine failure.
 
Pretty interesting poll. The answer is the plane will stall at a higher IAS, for two reasons

-compressibility effects on the airspeed; the ASI will read higher than it should
-airflow separation due to shockwave effects at a high TAS
 
E_Dawg said:
Pretty interesting poll. The answer is the plane will stall at a higher IAS, for two reasons

-compressibility effects on the airspeed; the ASI will read higher than it should
-airflow separation due to shockwave effects at a high TAS
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I thought it was the same indicated airspeed. Fewer air molecules entering the pitot tube as well as less lifting capability for the wings keeps the stall speed the same in respect to indicated airspeed, but higher in regards to TAS.

Maybe that is just the basic they teach for the PPL though.
 
Matt13C said:
Maybe that is just the basic they teach for the PPL though.
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It's actually Mach number dependent, rather than altitude dependent. For piston airplanes, the Mach number is so low, you really won't see the effect, so it's appropriate to teach students the constancy of IAS for performance-related airspeeds.

In the Mach .2-.3 range you actually may see a stall speed reduction, because the increase in Reynolds number has a stronger effect than Mach number.
 
tgrayson said:
It's actually Mach number dependent, rather than altitude dependent. For piston airplanes, the Mach number is so low, you really won't see the effect, so it's appropriate to teach students the constancy of IAS for performance-related airspeeds.

In the Mach .2-.3 range you actually may see a stall speed reduction, because the increase in Reynolds number has a stronger effect than Mach number.
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Could you design my next airliner? Thanks....

As to the stall speed, I bug what the FE tells me to, and stay in between them. We did have a low buffet of 207 at 380 the other day.
 
mikecweb said:
Isn't that what they call a helicopter cockpit.
yak yak yak
:bandit:
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Shoot - felt like I was in a coffin jammed in the back of your Lear fearing for my life because I saw you intentionally flew through clouds WITHOUT an autopilot on.
 
Ian J said:
Shoot - felt like I was in a coffin jammed in the back of your Lear fearing for my life because I saw you intentionally flew through clouds WITHOUT an autopilot on.
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Sorry for the rough ride honey.
I was waiting for you two to spoon back there.
 
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