Quote:
Originally posted by Samueul:
Quote:
Originally posted by JMo:
[b]Being a pilot, the myth that a plane could take off from a tredmill is impossible. Its not the speed the wheels are travleing that make the plane take off. its the speed of the air iver the wings which creates the lift. Now, it would be possible for a plane to land or i guess even take off vertically, given the right wind conditions for the specific plane. I've heard of a navy pilot land on an aircraft carrier the was heading into hurricane force winds. he practically hovered over the ship into the wind and touched down. his relative motion was very slow but his airspeed was still over 100 knots. just like i've had my cessna start to go back watds druing slow flight.
Um,,, That's exactly why it would take off, because the ground speed and the wheels don't matter and it's the initial thrust pushing the plane through the air that generates lift below the wings etc. Since the plane isn't anchored to the treadmill, it's going to take off no matter how fast the treadmill goes in the opposite direction.[/b]
What "initial thrust"? I'm not following your explaination.

An airplane on a treadmill would not generate the necessary airspeed over its wings to produce lift required for flight.

Here is an example:
An airplanes takeoff airspeed is 80mph. This means the air must travel over the wings at 80 mph, the ground speed is irrelevant. If it takes off in a no wind condition, it must have a ground speed of 80 mph to have the required 80 mph airspeed. If the plane takes off into a 20mph headwind, it only needs to travel at 60mph ground speed to generate an 80 mph airspeed over its wings. Now if it has a 20 mph tailwind, it must have a 100mph ground speed to achieve a 80mph airspeed.

So if this same plane was on a treadmill going 80mph (ground speed), what would the airspeed over the wings be?

The answer is zero. With a zero mph airspeed over the wings the plane would generate no lift, and it would be unable to overcome the force of gravity.