A plane on a conveyor belt

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Listen again:

The conveyor belt is the length of a runway.......not just a little treadmill under the plane

The Plane isn't trying to stay stationary or match the speed of the conveyor belt.

The conveyor belt matches the speed of the wheels NOT the plane

The plane hurtles along the belt powered by the engines and takes off as normal the wheels will be spinning twice as fast that is the only difference.
 
Ken said:
The engines keep the plane on the belt.
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Are you saying the plane stays still relative to the ground? If so, you're wrong:

By Newton's second law of motion, any object with a force acting on it will accelerate in the direction of the force.

By Newton's third law of motion, the force exerted on the air inside the engines must have an equal and opposite effect on the engines themselves (which are attached to the plane; so thus on the plane as well).

Therefore, the exhaust gasses and the plane will move away from each other with equal momentum. Since the air inside the engines is initially stationary (before being accelerated out of the back) with respect to the ground, the acceleration of the plane will be relative to the ground, not the conveyor belt.

If the plane were to stay still, then the force produced by the plane's engines would have to be countered in some way. I'm rather doubtful that the conveyor belt could produce the 1 million Newtons of force (taking a 747 as the plane) required to keep the plane still.

Unless you're saying that the air's going to be moving of its own accord towards the plane while the plane sits still :confused:
 
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So the whole point of this thread is:

Can a plane take of if its wheels are spinning at twice their normal take of speed?

If it gets the same forward momentum as it would normally, then i will tick the yes box
 
What would happen if you were to put a helicopter on a massive rotating disc (record player) which was spinning in the opposite direction of the counter torque created by the turning rotors? Would that be able to take off?
 
Mat said:
What would happen if you were to put a helicopter on a massive rotating disc (record player) which was spinning in the opposite direction of the counter torque created by the turning rotors? Would that be able to take off?
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No because the pilot would be sick and get out. :p
 
Mat said:
What would happen if you were to put a helicopter on a massive rotating disc (record player) which was spinning in the opposite direction of the counter torque created by the turning rotors? Would that be able to take off?
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No, unless the helicopter had wheels pointing in exactly the right direction :)
 
Mat said:
What would happen if you were to put a helicopter on a massive rotating disc (record player) which was spinning in the opposite direction of the counter torque created by the turning rotors? Would that be able to take off?
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So for example the body of the helicopter is moving clockwise and the rotors anticlockwise at the same rpm, just in oposite directioins?

Then no it won't take off because the rotorblades wouldn't be moving anywhere relative to their original position.

*prepares to be attacked as I probably missunderstood the question or messed something up*

Reasoning: heli body is moving at +100rpm (taking clockwise to be positive) which means the rotors if the engine were turned off would also be moving at +100rpm. Turn the engine on and the rotors are now turning at -100rpm. +100rpm-100rpm = 0rpm. So from an oberservers point of view (not standing on the moving turntable) the rotors arent moving, and and thus not moving through the air and so are not creating any lift.

Inquisitor said:
No, unless the helicopter had wheels pointing in exactly the right direction :)
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I assumed the helicopter was on ski's and the skis had infinte friction with the turntable so no slip occured.
 
all this talk of jets and planes has reminded me of that stunt on (i think) Top Gear, where they powered up a Jumbo Jet (virgin atlantic?) and pushed a caravan out into the stream and it got obliterated.
can't find it on youtube though, :(

anyone remembe that, have a clip of it?
 
Cruiser said:
all this talk of jets and planes has reminded me of that stunt on (i think) Top Gear, where they powered up a Jumbo Jet (virgin atlantic?) and pushed a caravan out into the stream and it got obliterated.
can't find it on youtube though, :(

anyone remembe that, have a clip of it?
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I recall it, they used various cars didn't they? Theres also a scene in Casino Royale where a police car gets blown away by a jumbo's engines.
 
Cruiser said:
all this talk of jets and planes has reminded me of that stunt on (i think) Top Gear, where they powered up a Jumbo Jet (virgin atlantic?) and pushed a caravan out into the stream and it got obliterated.
can't find it on youtube though, :(

anyone remembe that, have a clip of it?
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http://www.youtube.com/watch?v=43OQb5Jb9Ms

Thats a 747 vs. Mondeo and 747 vs. 2CV

Well technically it's only half a 747, only the two inboard engines were running.
 
A conveyor belt would not stop the plane from taking off, it would only increase the distance needed for it to take off. If the belt matched the planes take off speed, it would need roughly double the distance to take off imo.
 
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