PPRuNe Forums - View Single Post - The "Aeroplane on treadmill" conundrum...
Old 8th Feb 2006, 11:55
  #46 (permalink)  
dublinpilot
 
Join Date: Feb 2002
Location: Dublin
Posts: 2,547
Likes: 0
Received 0 Likes on 0 Posts
Jafo,

Ignore my arguments above, because they are really more theory than practice.

Try to think of it the other way around; an airplane landing on a conveyor belt.

The airplane is in a 60kt headwind, and the pilot leaves some power on......enought to maintain level flight with a nose up attitude.

Just as the airplane is about to touch down the pilot flares a little more so that the wheels barlely touch down, and the weight of the aircraft is partly supported by the wheels and partly by the conveyor belt.

All that happens is that the wheels are spun by the conveyor belt, but the engine still pulls the plane forwards though the air, and the airflow over the wings support it weight.

The pilot then lets the angle of attack fall so that all the weight is now supported by the wheels, but leaves the engine running. The airplane still stays stationary on the conveyor belt.

If the pilot now applies full power, the aircraft accellerates forward and climbs away.

All the conveyor belt is dowing is spinning the wheels. The airplane is pulling against the air, not the belt (ignoreing friction).

I hope that helps!

dp
dublinpilot is offline