Airplane on a Conveyor Belt...

[Shuffler]

For those who see no counter force to thrust being applied by the belt answer whether the speed of the belt makes any difference?

They original post says the belt is traveling the opposite direction at the same speed as the plane.

For those that dream about a conveyor belt moving instantly, you can also dream about tires that will not shred just as the belt does not shred.

[AKIron]

Pretty sure the original post in the original thread said the wheels. This thread is referencing the other thread which I could not find. It has been a loooong time ago.

[AKIron]

Just to be clear. A plane can take off on any conveyor belt that is moving only as fast as the fuselage of the plane with respect to the ground or wind. No problem. Anyone who thought it wouldn't was confusing the thrust of the prop with the wheels that drive a car. That is settled.

Now for a question that could have been inferred from the original.

Can a plane on a conveyor belt take off if the belt can instantly match the rotational speed of the wheels, without limit?

[NatCigg]

since any good airplane would apply a very large amount of thrust, independent of the conveyor, that will move the plane forward almost as if it was on solid ground. because of the planes acceleration in space, the wheels will always be moving faster than the conveyor, causing the conveyor to speed up, depending on the conveyors ability to accelerate and the tire and bearing assemblies ability to handle the speed,  a theoretical infinite speed would be obtained until the plane reached takeoff airspeed and the tires leave the conveyor. 

[Vraciu]

For those who see no counter force to thrust being applied by the belt answer whether the speed of the belt makes any difference?

Negligible. 

[AKIron]

Given indestructible wheels and an infinite speed belt there is still inertia and force to be considered. An infinite speed belt can easily counter the force of a non-infinite thrust power plant in a plane thus holding it in place.

Given an infinitely powerful engine which will win? The immovable object or the irresistible force? One will be proved false. Both cannot exist relative to the other.

[AKIron]

Even if the wheels were theoretically frictionless they still have mass and thus inertia. An accelerating belt can apply force to those wheels opposite the direction of the plane's thrust. How much force just depends on how fast the belt accelerates. The plane's thrust is not infinite but unless you apply a limit, the belt's acceleration and thus "drag" is infinite.

Find the original thread and see how the question can be interpreted two ways. No one who understands the inertia question believes the plane won't take off with a belt moving a mere 200mph.


 

[Zimme83]

The original question was if the plane could take off from a conveyor belt that matched the speed of  the plane but in the opposite direction. But of course you can get any result you want by creating a theoretical setup were the belt can move at infinite speed etc..

The plane will take off - if the wheels can take the load of spinning twice as fast. The belt cannot hold the plane down but it can destroy the wheels. For a General Aviation aircraft it should be no problem since they get airborne at 60 or so knot so twice that is 120 knot, which is not extremely fast. For a jet liner however, with a rotation speed of let say 160-170 knots it would probably be some issues. 320+ knots on the wheels would almost certainly shred them apart. 

But still: Its crucial to understand that a plane is not like a car in this case, a car need to use engine power to match the speed of the belt and will quickly run out of power, a plane don't need to do it since it  moves by moving air and the belt only affect the free spinning wheels.

So there you have it - again.....

[Bizman]

Let's turn the question around: What would happen if an aeroplane landed on a conveyor belt moving in the opposite direction matching the speed of the plane? Would that make the plane land on a spot? And if so, why hasn't this been applied to carriers?

[FLOOB]

Let's turn the question around: What would happen if an aeroplane landed on a conveyor belt moving in the opposite direction matching the speed of the plane? Would that make the plane land on a spot? And if so, why hasn't this been applied to carriers?

Obama?

[Zimme83]

Let's turn the question around: What would happen if an aeroplane landed on a conveyor belt moving in the opposite direction matching the speed of the plane? Would that make the plane land on a spot? And if so, why hasn't this been applied to carriers?

It hasn't been applied to carriers because it doesn't work and would be very expensive to do. And even if it did work it would be a bad idea since thanks to the acceleration. Land a plane flying at 130-140 knots on the spot will inevitable rip the plane apart and most likely kill the pilot.

In reality it would be like a normal landing, except that the wheels are accelerated to twice their normal speed.
A much better idea would be to build a huge fan to blow the air over the ship/runway at a speed that matched the speed of the plane.

[AKIron]

The original question was if the plane could take off from a conveyor belt that matched the speed of  the plane but in the opposite direction. But of course you can get any result you want by creating a theoretical setup were the belt can move at infinite speed etc..

The plane will take off - if the wheels can take the load of spinning twice as fast. The belt cannot hold the plane down but it can destroy the wheels. For a General Aviation aircraft it should be no problem since they get airborne at 60 or so knot so twice that is 120 knot, which is not extremely fast. For a jet liner however, with a rotation speed of let say 160-170 knots it would probably be some issues. 320+ knots on the wheels would almost certainly shred them apart. 

But still: Its crucial to understand that a plane is not like a car in this case, a car need to use engine power to match the speed of the belt and will quickly run out of power, a plane don't need to do it since it  moves by moving air and the belt only affect the free spinning wheels.

So there you have it - again.....

Maybe that was the original question posted to Mythbusters but it was not the original question posted here. That was well before this particular thread was started in 2008.

[Bizman]

Have I already made it clear that I believe in takeoff unless the landing gear fall apart on the conveyor belt?

[Vraciu]

The original question was if the plane could take off from a conveyor belt that matched the speed of  the plane but in the opposite direction. But of course you can get any result you want by creating a theoretical setup were the belt can move at infinite speed etc..

The plane will take off - if the wheels can take the load of spinning twice as fast. The belt cannot hold the plane down but it can destroy the wheels. For a General Aviation aircraft it should be no problem since they get airborne at 60 or so knot so twice that is 120 knot, which is not extremely fast. For a jet liner however, with a rotation speed of let say 160-170 knots it would probably be some issues. 320+ knots on the wheels would almost certainly shred them apart. 

But still: Its crucial to understand that a plane is not like a car in this case, a car need to use engine power to match the speed of the belt and will quickly run out of power, a plane don't need to do it since it  moves by moving air and the belt only affect the free spinning wheels.

So there you have it - again.....

160-170 is F-105 territory not an airliner.

[morfiend]

Go offline enable storch on the CV and set wind at 10 mph south,now set course due north for CV and take off in storch!

   If you film and run the film backwards it will look like a landing! The storch will takeoff as the CV motors away infront of you!