Wait wait wait WAIT!






Is the treadmill plugged in? Cause that could be the difference!

 

YES THE PLANE WILL TAKE OFF!

The wheels can spin back or forward, the treadmill can spin back or forward, because the propulsion is created by the jet engines, the plane will move forward.

If the wheels are what propelled the airplane to reach the speed required then the treadmill would cancel out the forward motion much like a car on wheels on a dyno. The cars wheels are what propel the car forward and they are connected by gearing and shafts.

The wheels on an airplane are not connected to anything and spin freely. The forward motion generated is from the engines and thrust.

If you are on a tread mill with a car, where your wheels are connected to the engine which generate forward motion and the treadmill is going equal speed in the opposite direction you will not move. Slam on the breaks and you and your car will go flying.

If you placed a treadmill under a plane and turn on the tread mill, the plane will not move. the wheels will just spin freely with the treadmill because the wheels do not create the force or propulsion. If you turn off the tread mill, the wheels will stop also and the plane will still not move. The wheels turning have no effect on the forward or reverse motion of the plane.

Turn on the engines and you will see that the plane now will move forward.

The plane will move forward on any surface, water or even ICE.

 

[QUOTE=Gymkata,Jan 28 2008, 12:24 PM] In order for the wings to do their work, you need sufficient airflow over them. If there is no relative motion between the wings and the air the wings will not produce lift. If the treadmill

 

Even Vanilla ICE?

 

So what pray tell is going to hold the plane in place on the treadmill? A giant pair of arms?



Here's the thing: If the plane was absolutely MOTIONLESS as the treadmill ran underneath it, then sure, we can believe the forward thrust generated by the engines would be enough to move the plane forward.

But, get this: A plane sitting on a treadmill with NO thrust, will *gasp* MOVE BACKWARDS.

(go ahead... think about it.)

The plane is attached to the treadmill via the wheels, and nothing else. Therefore, the plane will move backwards as the treadmill goes backwards.

Now... if you turned on the engines to provide thrust to counteract this backwards motion, the plane would be motionless, and those "giant arms" you spoke of earlier will be in effect. If the plane has enough thrust to create the necessary lift-off speed on TOP of the treadmill's effects pulling it backwards, then sure, it can take off.

But don't act like the treadmill doesn't make a difference.

 

 

Sorry Tim, I don't believe this to be true.

Think of it like this: The earth is moving, yes? Think of the earth as a giant treadmill.

Now... do planes parked on an airstrip roll along freely above the earth (giant treadmill)? No. They move WITH THE EARTH (giant treadmill).

It's only enough thrust to create enough forward movement IN ADDITION to the movement of the treadmill that the plane will take off.

 

Tell you what... next time you're at a big airport with a moving sidewalk, why don't you put your rolling luggage next to you and let go of the handle. Let me know if it stays where it is, or moves backwards.

 

Your earth to treadmill analogy only works if your treadmill creates its own gravity field.

But you are right that a plane would move backwards on a treadmill if there were no thrust being provided by the engine(s) unless is has frictionless wheels. But once the engines are engaged the treadmill is a non factor, regardless of how fast it starts moving.

David

 

[QUOTE=Fear Itself,Jan 28 2008, 10:06 PM] Your earth to treadmill analogy only works if your treadmill creates its own gravity field.