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nema
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Stall / Speed Question

Sun Nov 15, 2015 7:46 am

Hi, i understand that when on final approach to landing an aircraft, the airspeed is the stall speed plus 30%.

So what is the take off speed in relation to the stall speed, is that plus 30% too and, is any speed lost on the initial climb?

Thanks.
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Starlionblue
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RE: Stall / Speed Question

Sun Nov 15, 2015 8:46 am

Quoting nema (Thread starter):
Hi, i understand that when on final approach to landing an aircraft, the airspeed is the stall speed plus 30%.

So what is the take off speed in relation to the stall speed, is that plus 30% too and, is any speed lost on the initial climb?

Approach speed may not be less than Vso +30%. It may be more.

Initial climb speed tends to be limited by Vmca (minimum control speed in the air on one engine at take-off power). This may be stall speed, but may also be above stall speed. In other words the wing can fly but there may be too much yaw moment with an engine out for the fin and rudder to counter.

The big difference is that with engines at take-off power you get a lot of yawing moment, but with engines at approach power you don't.

V2 speed is the take-off safety speed, which allows for a climb on one engine. Typically with all engines operating you'll climb out at V2+10 or so. If you lose an engine V2 is the minimum.

[Edited 2015-11-15 00:49:14]

[Edited 2015-11-15 00:51:07]
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Pihero
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RE: Stall / Speed Question

Sun Nov 15, 2015 12:18 pm

Quoting nema (Thread starter):
So what is the take off speed in relation to the stall speed, is that plus 30% too

First one would have to define *Takeoff Speed* ; Normally, the first one you hit when airborne is *V2*, which has to be higher than 1.2 Vs ( the stall speed in the configuration).
Things get a bit more complicated, depending whether you are considering an all-engines-operating takeoff or one with an engine failure( which we do at every takeoff for safety margins' reason ).... and whether you deal with FBW airliners - for which the stall speed definition is different.

See " Getting to Grips With Aircraft Performance " a very thorough article on the subject ; You'll find it at smartcockpit under OPS and " Aerodynamics and Performance".

(BTW, it is a now vastly updated booklet with new chapters like flex and derated T/Os, Fuel planning... etc...

For some airline cadets, it is highly recommended   

Cheers !
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