Surely it would depend on the friction of the wheels against their bearings/hubs? If perfectly frictionless then the conveyor would have no effect, however if there was any friction then the conveyor would serve to slow the plane down.
A plane on a conveyor belt
- Thread starter iBot
- Start date
- Status
Soldato
Dude the plane has to have momentum if it has none it won't leave the ground
Soldato
If we assume that the plane stays stationary, then no it's doesn't take off.
However, the plane won't stay stationary because the interaction between the wheels and the belt is irrelevant. Consequently it will still move forward under the power of the engines and will take off.
Imagin the plane is doing 400mph on it's wheels on the belt and then imagin the plane in exactly the same position, same height above the belt, but doing 400mph with it's landing gear up. If the plane in the second example will fly, then so will the first.
However, the plane won't stay stationary because the interaction between the wheels and the belt is irrelevant. Consequently it will still move forward under the power of the engines and will take off.
Imagin the plane is doing 400mph on it's wheels on the belt and then imagin the plane in exactly the same position, same height above the belt, but doing 400mph with it's landing gear up. If the plane in the second example will fly, then so will the first.
Last edited:
Associate
I had a big discussion a while back on another forum about this, and it took three pages for me to realise that the plane would actually take off.
Basic if the plane is moving towards the end of the conveyor belt at 10knots, then the belt will be spinning the other way at 10 knots, and the wheels will be spinning at 20kts and so the plane it moving forwards (relative to the surrounds and not the conveyor belt) at 10knots. It the plane to moving forwards at 75knots, the conveyor belt is moving in the opposite direction at 75knots, while the wheels are moving at 150knots. The plane is still moving forwards, it just to fact that the wheels are moving faster.
Basic if the plane is moving towards the end of the conveyor belt at 10knots, then the belt will be spinning the other way at 10 knots, and the wheels will be spinning at 20kts and so the plane it moving forwards (relative to the surrounds and not the conveyor belt) at 10knots. It the plane to moving forwards at 75knots, the conveyor belt is moving in the opposite direction at 75knots, while the wheels are moving at 150knots. The plane is still moving forwards, it just to fact that the wheels are moving faster.
it will be moving the same speed into the air as always! well minus the slight drag from friction in the wheel bearings , effectively itl just be as though its on skis
Soldato
The plane gets its lift via the bernoulli effect. This has to do with wing shape and its interaction with air moving rapidly past. If the plane has no motion relative to the wind, there will bo no lift to force the plane up. That plane is going nowhere fast.
Soldato
No offence mate, but he's right. What you said basically makes no sense at all in aeronautical terms. The aircraft WILL be moving, the belt will only make the wheels turn, there is no power transfer from the wheels to the ground.
that makes a little more sense, but your wrong because the aircraft WILL have motion and so lift will be created.
why wouldnt it have momentum ?
its the jet engines giving it the forward momentum , planes arent driven at the wheels like a car !
Soldato
Look up one post
Soldato
If the entire runway is a conveyor belt, then yes it will take off as the engines will move the aircraft regardless of whether the wheels are spinning due to the conteraction of the conveyor belt.
Think about it this way, if you're running on a treadmill and someone pushes you, you're still gonna fly off the end of the treadmill regardless of what your legs are doing
Think about it this way, if you're running on a treadmill and someone pushes you, you're still gonna fly off the end of the treadmill regardless of what your legs are doing
Soldato
what if theoetically you had a giant fan blowing onto the nose of the plane recreating it running down the runway, would it take off then?
Soldato
I read that quote on the first google hit too.
However, you are assuming the plane won't move, when it will, it's just that the wheels will be turning twice as fast.
The momentum isnt generated by the wheels like it is in a car, it is generated by the engines pushing against the air. If you stand on a skateboard and shoot a fire extinguisher behind you, you will move even though you havent pushed with your feet.
it DOES have motion relative to the wind ! , the wheels have no effect whatsoever
think of the planes that land on water , planes dont use wheels to move forwards they just use them to reduce friction between the plane and the ground
Erm, it has big things called engines, which push lots of air backwards very quickly. Historically, these "engine" things have proven to be quite good at providing momentum.
Soldato
read my post again.
As one of the other posts, yes if you have a fan that can blow air over the wings at around 150 knots then yes the aircraft will become airbourne without moving one inch.
This is 100% correct.
This is not.
The point most people miss is that the plane will move forward, therefore there is movement, and so lift. The fact that the wheel speed matches the conveyor speed does not mean that the plane doesn't move forward.
- Status