Imagine a plane is sat on the beginning of a massive conveyor belt/travelator type arrangement, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
There is no wind.

Can the plane take off?

What?
Wheels don't make an airplane fly.
Airspeed verses ground speed.
Maybe I don't have a clear picture of what you're talking about.

Larry

The thrust will result in the same airspeed as without the conveyor, so it can take off.

yes

I answered yes. but... If the plane starts to roll forward, the belt will start to move backwards. As a reaction, the wheels will have to turn harder to keep up with the plane, leading to an increased speed of the belt. At takeoff speed (say 120 kts), the speed of the belt will be also 120 kts and the wheels will spin at 240 kts equevalent, which may cause them to fail. Does this sound reasonable?

Yes, it will fly.

Suppose the plane's wheels are replace by powerful magnets with the north-seeking poles of the magnets pointing down. Suppose the conveyor belt is replaced conveyor belt composed of a series of electromagnets (imagine a cobblestone belt of magnets) with the north-seeking poles pointing up. The two sets of magnets will repel each other, levitating the plane. The propeller begins to turn pulling the plane forward and the belt begins to move at the same speed in the opposite direction. The plane's ground speed will increase and the plane will take off.

The only difference is that in the original setting the wheels appear "tied" to the ground. If fact they are not. The wheels will rotate at twice the rate that they would if the conveyor belt was stationary.

The wheels can be concidered somewhat detached from the airframe; i.e. the wheels could be moving freely with the conveyor belt moving in the opposite direction but the plane would still be stationary.
When the plane is in motion, the wheels will move accordingly, probably spinning faster, but the plane should still be able to take off under airspeed as it would normally would. I am probably wrong but some others have put 'yes' too. Reason please. And perhaps a practicle test would be nice. Actually, its not a bad science project, thanks for the idea

James,


Edit- P.S. looks like we all replied at the same time

Wow this filled up fast.

Many forums are debating this right now. So i threw it on this one.

I believe the answer is yes. So far its been on car forums and others, but i wanted it on a forum with some pilots.

http://www.naplesracing.com/thread.p...tuser=0&page=1

http://forum.physorg.com/index.php?showtopic=2417&st=0

http://community.discovery.com/group...7451937218/p/1

http://videos.streetfire.net/player....D-D6BA1A43A06B

Haha, bet those who put 'NO' feel silly now .

James,

As the wheels supply no thrust the plane will take off whether the conveyor moves or not.

No, it won't take off.

If the conveyor belt is exactly matching the wheel rotation in the opposite direction, the plane will remain stationary relative to the air around it. Most of the thrust will be transfered to the movement of the conveyor belt through friction with the wheels. Therefore no airspeed at all, no lift.

If you started with the brakes of the plane on would the conveyor belt still move ?.

as far as the magnets go you could actually not have to make it move if the north/south was in the right config. just set the plane balanced on the field then give a push/thrust. It could then accelerate on the "field"

Originally Posted by Usta Bee

If you started with the brakes of the plane on would the conveyor belt still move ?.

No. The belt only moves when the wheels try to.

This whole conveyor belt thing reminds me of the Sanger Silverbird/ America bomber (only they were gonna use rockets)....

http://www.luft46.com/misc/sanger.html