Will it fly(don't answer too fast)?

[OTTOL]

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

The question is:

Will the plane take off or not? Will it be able to run up and take off?  ???

[ozzy72]

It won't as it isn't generating airflow over the wings to give lift!

[OTTOL]

Did you approach it from a mathematical or philisophical perspective?

Most people (myself included) tend to go with what they think is the obvious answer......initially.

[Woodlouse2002]

It won't because the plane isn't moving in relation to the earth.

[Saitek]

It'll just go really fast on the spot!

[Omag 2.0]

Yes it will!

possibilty one! There is a power-black-out, causing the conveyer to stop... watch the plane as it moves... but don't stand in front of it.

Possibility two! There is a sudden drop of engine-pressure and the engines quit. Seconds after that event, the plane will fly in reverse mode!

Possibility three! The events are beeing witnessed from an other standpoint than the earth. In that case, the plane will be flying in a concentric way around the sun, while revolving around the centerpoint of the earth.

[Craig.]

I theory yes it would. Remember this isn't like the rolling roads used by cars as they hold it in place on rollers. However it would require one hell of a long runway. or so I am guessing.

[Woodlouse2002]

I theory yes it would. Remember this isn't like the rolling roads used by cars as they hold it in place on rollers. However it would require one hell of a long runway. or so I am guessing.

Yes but the plane is being taken backwards by the conveyor at exactly the same speed it's going forwards therefore it's not moving and the length of runway is irrelevant.

[beaky]

I'm keeping out of this one... been through it elsewhere.
Enjoy...

[eno]

It will take off !!! ........... the wheels aren't powered  and therefore the engines aren't driving them. The engines are producing thrust against the air not the conveyer.
The wheels and gear will probably excede their rated speed though by 2X.

[TSC.]

Contrary to popular belief it is the rate of speed that air passes the wings that creates lift, not how fast the wheels are turning.

If the engine is producing enough power to make the plane travel at 100mph & the conveyor belt is turning in the opposite direction at 100mph - then the plane is going no-where - nor is the air around the plane.

So I would have to say no, the plane won't take off.

Thats my theory anyway - now I have to stick around to see how it works out.

Cheers,

TSC.

[Omag 2.0]

I agree with TSC, no airflow, no flying... simple physics...

[Souichiro]

I agree with TSC, no airflow, no flying... simple physics...

And then they designed Choppers...

[Omag 2.0]

Still the same principle... airflow is generated around the blades by rotating them trough the air, causing the difference in airpressure above and under the rotorblade... so there's lift!

In the planes+conveyer case, nothing causes airflow over the wings...

[Craig.]

Helicopters are no differant to planes in that they need airflow over the wings to fly, the differance is their wings are smaller and rotate at god knows how many 1000 rpm.