Power-off stall versus power-on stall:
- Power-on stalling speed is higher because the propeller slipstream increases the effective airspeed over the wing
- Power-on stalling speed is lower because the vertical component of thrust helps support the aircraft weight, reducing the lift requirement
- Power setting has no aerodynamic effect on the stalling speed regardless of engine type or thrust line orientation
Explanation
With power on, part of the thrust acts upward (and the propeller slipstream increases dynamic pressure over the wing), so the wing needs to produce less lift to balance weight and the aircraft stalls at a lower indicated speed than power-off. Power therefore lowers, rather than raises or fails to affect, the stalling speed.
kspyroglou asking:
How can that be true? Thrust is a horizontal component acting parallel to the aircraft’s line of direction.
Community Comments (1)
G
Gioppo Posts: 3 24.03.2026 / 20:17
If you imagine a plane stalling, the nose is expected pitching up. Hence the thrust is split beetween orizontal and vertical components. This way it contributes to lift, making the whole power-on stalling speed a bit less than the power-off one. An extreme example are post stall manouvers of some high perfonmance fighters, namely the russian ones.
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