# Stall Speed

Which is usually bigger, Stall Speed during take-off or Stall Speed during landing?

Stall speed on takeoff is higher, because you are heavier on takeoff than you are on landing.

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Hereâ€™s a general rule of thumb: the heavier the aircraft, the higher the stall speed.

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Thank you so much for the answer. This do help me a lot!

Additionally, you are normally only Flaps 5 on Boeing and 1 on Airbus on takeoff while you are flaps 30/Full on landing. The higher flap settings also decrease your stall speed so the stall speed on takeoff is much greater.

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Takeoff because your weight is heavier than during landing when your weight have to be light . ( depend, if you have an emergency and the type of emergency) .

That and on landing you have the momentum because your descending, on take off you have to gain it.

Air temperature can also effect this

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During landing gravity is working with you; during takeoff itâ€™s working against you.

This is a change in force which acts to either increase of decrease your forward speed, but it doesnâ€™t change the stall speed itself, only how much help or hinder you get in moving toward or away from that speed.

GS yes, but not IAS

Ye but what I mean is it increases the throttle threshold. You typically need more throttle so it can be harder to get to speed.

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The OPâ€™s question was about stall speed, you mentioned

Momentum is fixed by the speed you are currently at, it is not itself immediately affected by the direction of gravity. Though the gravity direction does act to change this momentum by accelerating or decelerating to a new speed.

Rather than momentum, itâ€™s actually potential energy (or height energy) that the throttle is managing. The throttle is power which is energy per unit time.

More throttle on take-off than landing is because on take-off you need to add potential energy (climb â€śup hillâ€ť), otherwise the climb will rob your forward speed to get the necessary energy (turning kinetic energy into height energy).

Less throttle on landing is because you are consuming potential energy (youâ€™re coming down from the hill), which replaces engine power (energy per unit time) to keep your speed up.

a bit of an edit:

When all is said and done, youâ€™ve spent chemical energy from your fuel on potential energy to give you altitude.

And that chemical energy which has now become height, gives you plenty of reserve energy to consume as you descend (potential energy to sustain flight is gliding).

Besides the fuelâ€™s chemical energy being converted into potential energy, some, of course also has to go to overcoming parasitic drag.

But also lift itself, stripped of all the parasitic consumption of energy, consumes chemical energy from your fuel tanks.

The wings mobilize some amount of air downwards to produce the pressure differential that keeps the wing up against the weight of the aircraft.

I had estimated elsewhere that for an A380 to be held up, itâ€™s an air mass equivalent of about 30 adult elephants every second being â€śthrown directly downâ€ť from about 0 to 60mph!

Throwing the elephants down is transferring kinetic energy to the elephants.

To the pilot the elephant throwing feels like drag (drag against forward motion rather than in the vertical direction) lumped in with all the parasitic drag.

That pure lift requires fuel burn (if in level flight).

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Uhhhhh oke then

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Also, donâ€™t forget, though there is a stall speed for each phase of flight, you can stall at any speed if you exceed the critical angle of attack.

So you can be on approach (or takeoff) and if you pitch up very suddenly, your angle of attack spikes up before your flight path can respond. If this angle is too large, at some point air canâ€™t curve smoothly around the excessive bend, and lift is lost. This is certainly modelled.

Again, you can stall at any airspeed.

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