It's been a while - and we have new blood...

[Albannach]

OK, here is a thought experiment/conundrum for all the clever-clogs on here.

You have an airplane sat on a huge conveyor belt. The conveyor belt is computer controlled such that its speed is always the same as that of the aircraft - only backwards; i.e. If the aircraft is moving forwards at 10mph, then the conveyor will move backwards at 10mph.

Will the aircraft be able to take off?

Assumptions:
1. The aircraft is otherwise normally capable of flying just fine, and the pilot is normally capable of flying this aircraft just fine.
2. The conveyor belt runway is more than long enough that if the belt didn't move the aircraft would have ample room to achieve take-off. There are no obstructions that would affect a normal take-off.
3. The runway is at sea level, the air is still, and the conditions are perfect.
4. All measured speeds are relative to a fixed point.

OK, so, will it fly or not? Please explain your answers if possible.

[Vultch]

Lift is provided by airflow over the wings

This can be by forward movement thru the air or by the propellor pushing air over the wings (I assume its a forward prop driven design).

If there is no airflow over the wings - no lift no flight.

[BUSHWHACKER]

Lift is provided by airflow over the wings

This can be by forward movement thru the air or by the propellor pushing air over the wings (I assume its a forward prop driven design).

If there is no airflow over the wings - no lift no flight.

What he said.

[Albannach]

Propellors don't push air over the wings, they pull the aircraft forward. Unless the propellor is at the back, in which case it pushes the 'plane forward.

It's the pressure differential caused by the shape of the wing and its forward movement through the air, that provides lift.

[Bazcam]

Yes, the plane will take off, no problems.

Forward movement is acheived by thrust from the engine or from the
propellor not from the wheels. When the plane gains speed and the conveyor
matchs it in reverse the wheels will simply turn at twice the speed of the
plane. Take off speed will still be acheived regardless of what the wheels
are doing. I think.

[BigBobE]

mythbuster have done that one....

Mythbusters

[BUSHWHACKER]

mythbuster have done that one....

Mythbusters

The conveyor speed wasn't computer controlled plus the plane exeeded the conveyor speed before it took off. The same thing happend when they tryed it with a radio controlled plane.

Inconclusive!

[gwh200]

It will take off, assuming the wheels are not mechanically linked to engine speed. If it was a car for instance. Imagine no wheels but super duper magnets. It would take off then. The wheels, if not mechanically linked to engine speed, would spin relative to the belt. I don't have any decent notation on this device, but a curve that shows x^2 would show what I mean. As one thing changes, the other thing changes wrt the other thing. This change is a square of the first function.

[madcampbell]

As Bushy says...think about it if you removed the wings and tried this would it fly? NO it wouldn't

You cannot get the lift without air flow. The plane is stationary because the speeds are equal.(not in the video that's why it flew)

If you go on a tread mill and match the speed how much head wind do you have? None ...because your not moving forward. (check your gps)

A para glider cannot just stand there on a day with no wind and take off, they need to run forwards or down a hill to get air flow over the wing

So now put the para glider on the tread mill and get him to match the speed with his chute laid out behind him....don't hold your breath for him to take off any time soon!

Put a boat plane on a river and get it to match the speed of the river will that take off?

[madcampbell]

whoops I could be wrong I didn't add x^2 into my thinking....

[gwh200]

There us a vital bit missing from the question. It does all depend on whether there are limits. If both functions tend to infinity(no symbol goddamit) then both might cancel each other. There are Definitely different sized infinities, so you would have to have both functions tending toward the same infinite structure.
Much more important to consider, is that instead of setting incomplete questions, that miss out vital logic, the OP might be better off with this.

This awaits people who, instead of setting questions on incompleteness, come to stay for a few days.

[Predictable Bob]

OK, here is a thought experiment/conundrum for all the clever-clogs on here.

You have an airplane sat on a huge conveyor belt. The conveyor belt is computer controlled such that its speed is always the same as that of the aircraft - only backwards; i.e. If the aircraft is moving forwards at 10mph, then the conveyor will move backwards at 10mph.

Will the aircraft be able to take off?

Assumptions:
1. The aircraft is otherwise normally capable of flying just fine, and the pilot is normally capable of flying this aircraft just fine.
2. The conveyor belt runway is more than long enough that if the belt didn't move the aircraft would have ample room to achieve take-off. There are no obstructions that would affect a normal take-off.
3. The runway is at sea level, the air is still, and the conditions are perfect.
4. All measured speeds are relative to a fixed point.

OK, so, will it fly or not? Please explain your answers if possible.

Surely most of this is irrelevant ?

If the plane is moving forward then it has airspeed regardless of the action of the conveyor belt, if it gains sufficient airspeed it will take off

[leighh]

What kind of speed ratings do aircraft tyres have?

[madcampbell]

What kind of speed ratings do aircraft tyres have?

Depends on the surface they are on and the type of tyre they are adding in the prevailing weather conditions and the air temp. So not an easy one to answer

[IanB2]

If you tied ropes to the planes wings and anchored them to the ground and ran up the conveyor belt, would the plane move backwards? No. The wheels on the plane are not what determines the movement of the plane, they are just idler wheels.

The plane gets its thrust from the props, the conveyor belt acting on the wheels can't exert enough friction to hold the plane back, the plane will move forward and achieve flight.

The riverboat example is interesting, but the X-factor is the river acting on the floats exerts FAR more resistance on the plane that the wheels in the example could ever hope to.