[thedoc (OP)]

When an airplane does a knife-edge pass (wings vertical), where is the vertical component of lift coming from to keep it in the air?

Thanks!
Cameron



Asked by Cameron Thompson


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[chapter podcast=1000454 track=13.09.05/Naked_Scientists_Show_13.09.05_1001274.mp3]  ...or Listen to the Answer[/chapter] or [download as MP3]

[evan_au]

During the knife-edge pass, the propeller/jets are angled slightly downwards, and this directs a flow of air downwards.
The body of the aeroplane is angled, and this directs a flow of air downwards.
This downwards force on the air provides an upward force on the aeroplane to keep it in the air.

[lightarrow]

During the knife-edge pass, the propeller/jets are angled slightly downwards, and this directs a flow of air downwards.
The body of the aeroplane is angled, and this directs a flow of air downwards.
This downwards force on the air provides an upward force on the aeroplane to keep it in the air.

I am not an expert at all, is it possible that the rudder also is used for this purpose?

[alancalverd]

All of the above. A true 90 degree bank produces no upward lift from the wings, but every nonvertical surface is acting to produce lift. To sustain a knifedge at constant height you need to angle the thrustline upwards or tolerate a significant loss of speed throughout the manoeuver.