Would the plane take off?

[tool]

This debate seems to be making it's way on every message boards so I tought I'd try it here.
So here it goes.

A plane (747 passenger jet) is sitting on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

The question is:

Will the plane (747 passenger jet) take off or not?

[Jeffy-CanCon]

No. Take-off is dependant on the lift produced by air moving over the wings at high speed. the speed at which the wheels are moving is irrelevant.

[gimp]

*edit again - Boy was I wrong. This is a pretty good debate.

[rkjunior303]

No. Take-off is dependant on the lift produced by air moving over the wings at high speed. the speed at which the wheels are moving is irrelevant.

exactly.

if the plane is stationary but yet the wheels are moving, the wings will not produce lift and the plane will not leave the ground. thats like rudimentary physics..

[rkjunior303]

This debate seems to be making it's way on every message boards so I tought I'd try it here.
So here it goes.

A plane (747 passenger jet) is sitting on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

The question is:

Will the plane (747 passenger jet) take off or not?

[magman007]

This debate seems to be making it's way on every message boards so I tought I'd try it here.
So here it goes.

A plane (747 passenger jet) is sitting on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

The question is:

Will the plane (747 passenger jet) take off or not?

absolutely not! there is no lift, no drag, no foreward momentum to create lift. Read about bernouli's law and see if you can understand how the pressure differrntial created by a leading edge creates lift. the plane couldnt just take off on a vertical plane, unless it is an aircraft capable of VTOL(Hellicopter, harrier, JSF, or an osprey)

the plane would be sitting still, it would be like riding a bike on a tread mill, absolutely useless.

_magman007 your local pilot


the only thing that would ever result from this conveyor idea would be if the conveyor went in the same difrection only faster than the jet is actually propelling its self and making its own sort of catapult system Ala aircraft carrier, which would be invariably too much stress on a 747's airframe and gear system.

Also, how would you suggest landing the beast of all of these runways were in motion?

[SCpoloRicker]

.

[magman007]

also, please link to what other forums are debating this

[maxama10]

thats great....

[maxama10]

yup

[neppo1345]

YES...the plane would take off

You people forget the the plane's motion is derived from the interaction of the jet exhaust with the air, and not from the planes landing gear with the tarmac.

If it was a car it would remain stationary, but the plane would have nothing to negate it's thrust and would therefore still accelarate.

Since there is nothing to counteract the thrust of the engines, the plane would still move forward on the conveyor and reach speed to take off.

The wheels would simply spin twice as fast (the groundspeed would be twice the airspeed until it got off the ground) and it might take more thrust to counteract the friction produced in the wheel bearings coeffecient of friction between the pavement...etc etc.

I am not going to school to be an aerospace engineer...I don't know what I'm talking about...
EDIT: Oh wait...I am...and I do...

[nippinout]

Please, for the love of Jebus, don't make me draw a free body diagram.

Let's assume a plane needs to hit 100mph to take off.

That plane is travelling at 100mph down the conveyor belt, and the conveyor belt moves in reverse at 100mph.

The plane is travelling at 100mph relative to the ground, and 200mph relative to the belt. The plane takes off.

The conveyor belt and its speed is irrelevant. Thrust is produced by the engines, and not at the wheels.

Let's take the same problem with a car with wings. The car is designed to fly if it hits 100mph. Hit the gas until the speedometer hits 100mph. The belt also moves at 100mph in reverse. The car's speed relative to the ground is 0mph. Car does not take off. The plane does.

If this thread hits more than 3 pages, anyone that answers incorrectly after that point should be re-educated. With my fist!

[wad04]

even if it could, once it leaves the belt wouldn't it flop anyway?

[nippinout]

even if it could, once it leaves the belt wouldn't it flop anyway?

The car on a normal runway would eventually lose speed once it gained altitude. A skilled car pilot could hop along.

[neppo1345]

YAAAAY...another smart person...