Coneyer Belt = Plane Speed

Plane is doing 170mph, Belt doing -170mph, Wheels turning 340mph

PLANE WILL TAKE OFF

hehe yeah.. the plane only has to make the 5kts effective tailwind up, and then it's on its way. It's difficult to make a new riddle out of an old one that's been baked, eaten, picked at and is now sitting, cold, in the middle of the dinner table.

So..

meh

How? Will it magically jump off the conveyor belt?

It needs LIFT to leave the ground, the speed of the wheels makes no difference! Unless there is air passing the wings, NO LIFT is generated so the wheels will merely be turning really fast.

Basically what you guys are suggesting equates to a plane with no wings. It'd go like shit off a stick along the ground, but there is NO FORCE to push it upwards. So irrelevant of how fast the wheels are turning, there is nothing to push it off the ground.

Quote from Dajmin :

How? Will it magically jump off the conveyor belt?

It needs LIFT to leave the ground, the speed of the wheels makes no difference! Unless there is air passing the wings, NO LIFT is generated so the wheels will merely be turning really fast.

Basically what you guys are suggesting equates to a plane with no wings. It'd go like shit off a stick along the ground, but there is NO FORCE to push it upwards. So irrelevant of how fast the wheels are turning, there is nothing to push it off the ground.

But it's a plane! They have wings!

Quote from Dajmin :

How? Will it magically jump off the conveyor belt?

It needs LIFT to leave the ground, the speed of the wheels makes no difference! Unless there is air passing the wings, NO LIFT is generated so the wheels will merely be turning really fast.

Basically what you guys are suggesting equates to a plane with no wings. It'd go like shit off a stick along the ground, but there is NO FORCE to push it upwards. So irrelevant of how fast the wheels are turning, there is nothing to push it off the ground.

Because it's got an airspeed.

Ground Speed (not conveyer belt): 170kts
Ground Speed (conveyer bet): 340kts
Air Speed: 170kts (assuming zero wind on the day)
Linear Wheel Speed: 340kts
Take off: Yes.

Why can't people grasp this. It's NOT a car. The wheels do not transmit power or torque (except a tiny amount of drag).

That makes no sense though. I'm assuming it's due to the phrasing of the question, but that way it makes the conveyor belt a pointless variable. They might as well have just doubled the wheel speed.

I had assumed that the conveyor belt was neutral speed, merely turning however fast the wheels made it turn, not that it had a defined speed of it's own.

The conveyorbelt is the red herring. The question is, can the person who's figuring out the answer to the question figure out that the conveyorbelt (and wheelspeed) is actually a red herring.

Quote from Dajmin :

That makes no sense though. I'm assuming it's due to the phrasing of the question, but that way it makes the conveyor belt a pointless variable. They might as well have just doubled the wheel speed.

I had assumed that the conveyor belt was neutral speed, merely turning however fast the wheels made it turn, not that it had a defined speed of it's own.

The belt is a pointless variable, but it doesn't have a fixed speed. In my example it's doing 170kts in the other direction to match the 170kts of the plane, thus making the wheels go twice as fast (340kts).

So to all intents they HAVE just doubled the wheel speed...

Quote from tristancliffe :

So to all intents they HAVE just doubled the wheel speed...

Alternatively if the belt was to go in the same direction of the plane and keep pace with speed of the plane the wheels wouldn't turn at all and the plane will still take off why this is so hard to see confounds also

Idd Glenn has hit the nail on the head.
The right way to picture this is to imagine the belt is moving FORWARD at the same speed as the plane. The engine pulls the plane along (Im imaganing a cessna proppeler thingy), and the plane moves forward. the belt matches speeds, so the wheels dont turn. BUT the PLANE is moving forward.
If you hit the reverse button on the conveyor, the plane is STILL moving forward, the wheels start spinning really REALLY fast, but the plane WILL be moving forward cause the plane pushes agains the AIR, not the ground. Remember plane wheels are free-spinning, not like car wheels which push agains the ground (and would push the belt backwards).

Or you could fix the plane's wheels, move the conveyorbelt forwards, and turn the plane's engine/s off. It'll still take off if the conveyorbelt is moving fast enough. Unfortunately, once it loses traction with the belt, it'll quickly be back down again.

OR turn off the plane's engine with the backwards converyor, then see that the plane does not move, conveyor moves backwards, wheels move forwards, plane dont move. Start engine, and now to the previous system, you have a new force acting on the plane (the engine, duh). This will make the plane move forward.

Now I feel bad, I've gotten everyone arguing

Again, make sure you are picturing a conveyor belt that is as long as the runway. The plane will simply take off as normal, in the usual distance, but the wheels will be spinning twice as fast due to the opposing speed of the conveyor belt. The belt is ONLY affecting the wheel speed, not the planes airspeed relative to the earth.

Imagine you have a model rocket. Instead of pointing the stand for it straight in the air, you point it parallel to the ground. Hit the switch, rocket engine fires, and the model takes off. Due to lack of steering, gravity may pull it straight into the ground, but it will still become airborne, even if the stand is mounted on wheels and on a conveyor belt.....

Quote from Dajmin :

How? Will it magically jump off the conveyor belt?

No, it will travel a specified distance down the conveyor belt, and when the engine(s) produces enough thrust to generate the airpseed needed to create lift, the plane will rotate.