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Old October 8th 07, 06:35 PM posted to rec.aviation.piloting
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Default Backwash Causes Lift?

Mxsmanic wrote:
Bertie the Bunyip writes:


Yes, they can, and do.


Which ones? How do you accelerate an aircraft without accelerating anything
downward?


Acceleration is the second derivative of position.

If the vertical postion of an aircraft is constant, i.e. straight and
level flight, the first derivative of the vertical position is zero and
hence the second derivative is also zero.

Acceleration is the first derivative of velocity.

If the horizontal velocity of an aircraft is constant, i.e. straight and
level flight, the deriviative of the velocity is zero.

An aircraft in straight and level flight is not accelerated.


--
Jim Pennino

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