# Does the airflow from a propeller over a wing contribute to lift? [duplicate]

How I understand it, the perfect propeller would move air rearward at the exact same velocity as the free stream, i.e. the propeller air will merge with the free stream and have no real influence on the flow-field over the wing.

However a non-ideal propeller (thus all real propellers) accelerates the air to a higher speed than the free-stream and thus alters the flow-field over the wing.

My question is: Does this airflow from the propeller increase the lift generated by the wing?

My question obviously assumes that the propeller and wing is in the same plane and that the air from the propeller thus hits the wing.

## marked as duplicate by Peter Kämpf, FreeMan, mins, fooot♦, Danny BeckettMay 19 '15 at 23:06

• Thrust is just lift by another name. – casey May 19 '15 at 21:05
• Except for a 90-degree mismatch in direction, perhaps? – MariusMatutiae May 10 '16 at 16:43

A propeller not affecting the velocity of the free stream air would not generate any thrust (or drag), as the propeller works by the principle of creating thrust by accelerating a large mass of air, $F = m * a$.