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# The treadmill
Will have no detectable difference to the take off.

The speed that the wheels are going round at is fairly irrelevant. Flight is based on airflow over the wings, not speed relative to the ground.

More effective would be a massive fan at the far end of the runway.
(fastandfurryous What was the question again?, Mon 8 Jan 2007, 16:37, archived)
# The speed relative to the ground does matter here,
because it's the same as the speed relative to the air.
The plane does move relative to the ground, and the air.

edit: aah, "the ground" meaning the surface of the treadmill, gotcha. That's irrelevant.
(I helped save b3ta! Newington, Mon 8 Jan 2007, 17:37, archived)
# but
if the plane was sat on the runway and they forgot to turn it off it'd end up wdged in a hanger.
(MrChimp previously Monsieur, Tue 9 Jan 2007, 1:43, archived)
# The speed relative to the ground
as in the actual ground, not the treadmill, is irrelevant too. The aircraft has to achieve a speed relative to the air to achieve flight.

Suppose the aircraft was a 747 with a rotate speed of 180kts. If there's a 30kts headwind, then it only needs to do 150kts relative to the runway for it to have 180kts of airflow over the wings, and thus fly.

This is why you always take off and land into wind.

It's also why an aircraft with a very low stall speed can fly backwards. A Tiger Moth has a stall of 35kts. If there's a 45kts wind down the runway it's entirely possible for it to have 40kts of airflow over the wings, but be moving backwards (relative to the ground) at 5kts.

/relative motion blog
(fastandfurryous What was the question again?, Tue 9 Jan 2007, 14:16, archived)