conveyor belt and plane answered at last ??

[pred]

The wheels are of no consequence, they do not propel the aircraft!

Whilst I see what you are saying, the wheels are of consequence, whilst they are not directly linked to the engines they are the ONLY way that the thrust can be converted to forward motion whilst on the ground. If they are of no consequence then engine tests where the pilot leaves the brakes on would make the plane take off rather than remain stationary.

If there were sufficient thrust, then the friction of the wheels on the ground (or less likely the friction of the brakes) would be overcome and the plane would skid along, but that's not part of the question.

During engine test the wheels are chocked, makes no difference to the brakes.

 

[securespark]

I agree, but only up to a point, Lord Copper.

For the plane to move forwards, it will indeed have to go faster.

If the plane's wheels were driven by its engine, you would be right. But they are not, they are independent of the engine, freewheeling.

So, regardless of what the conveyor belt is doing to the wheels, the plane's engine will move the plane forwards and it will take off.

 

[pred]

Power, wheels or anything else doesn't come into.

For the plane to move forward it has to go faster than the belt, believe it or not that means the wheels have to go faster than the belt. Simple

The belt/car is a good example of equilibrium, take the engine out and fit a propeller and you achieve the same equilibrium unless one goes faster..

The wheels are not reacting with the belt!!

The engines are reacting with the surrounding air, so only if the air is travelling at the same speed as the belt would the aircraft remain static but as the air speed rises guess what.

http://youtu.be/_CDLbokf9sg

 

[Mw Roofline]

Mw Roofline and mitch66

We all know the plane can go forward, but read the question and Mw rooflines wonderful post.

As he/she rightly says the belt can go as fast as you like, and he can hold me in the same place with wheels whizzing round at the same speed as the belt I'm stood on.

Now the tricky bit, I need to go faster than the belt to get an air flow, but to do that the wheels must turn faster than the belt.

Same with the tread mill, it is running at 5 mph so to stay on it I have to walk or roller skate at 5 mph, if I do less I go backward, but if I go faster than 5mph I can go forward, but them I'm going faster then the belt

There is no power to the wheels and there is no power to your legs. You've got an engine strapped to your back. The wheels which have no power train (just on bearings) absorb whatever speed the treadmill is going at.

If there was power to the wheels then it would be an entirely different matter. You don't think the wheels are driving the plane along, do you?

 

[doitall]

So, regardless of what the conveyor belt is doing to the wheels, the plane's engine will move the plane forwards and it will take off.

But not without the wheels going faster than the conveyor belt.

 

[Mw Roofline]

For the plane to move forward it has to go faster than the belt

Can you explain this? I'd love to know.

 

[Mw Roofline]

So, regardless of what the conveyor belt is doing to the wheels, the plane's engine will move the plane forwards and it will take off.

But not without the wheels going faster than the conveyor belt.

Dude, you gotta forget about the bloody wheels, lol they doing nothing just spinning by themselves

 

[doitall]

And that is the only way you'll get the plane in the air is to forget the wheels.

The question say the wheel speed has to match the conveyor. So the answer is no the plane cannot take off.

 

[securespark]

So, regardless of what the conveyor belt is doing to the wheels, the plane's engine will move the plane forwards and it will take off.

But not without the wheels going faster than the conveyor belt.

How does this work - can you explain it?

The wheels are not driving the plane forwards, the plane's engine is.
The wheels are just reacting to the conveyor belt as they are in contact with it. What is influencing the position of the plane relative to the belt is the plane's engine.

 

[crank39]

For the plane to move forward it has to go faster than the belt

Can you explain this? I'd love to know.

The answer is in your very fine first post MW, the belt travels backwards at 250mph so rollerskate wheels are going like crazy and must be going 250mph also, when you say you applied pressure on your friends back and easily pushed him forward up the belt the surely the wheels must have spun just a little bit faster than 250mph

 

[pred]

Think of it this way, "thinking outside the box ) put a push bike on a conveyor, so far so good start the belt rolling and the wheels start rotating, NOW push the bike forward, it makes no difference what speed the belt rotates at when you push the bike it moves in the direction you choose.

 

[doitall]

An aircraft is standing on a very long runway that can move (a conveyor belt). The aircraft moves in one direction, while the conveyor belt moves in the opposite direction. This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels, but in the opposite direction. There is no wind. The pilot begins to add thrust to the engines...

This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels

Belt and wheels are going at the same speed as the car in the video.

The plane has to go faster than the belt to make ground over it and get to take off speed, which means the wheels must go faster than the belt.

It's all quite simple really if you read the question.

 

[crank39]

An aircraft is standing on a very long runway that can move (a conveyor belt). The aircraft moves in one direction, while the conveyor belt moves in the opposite direction. This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels, but in the opposite direction. There is no wind. The pilot begins to add thrust to the engines...

This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels

Belt and wheels are going at the same speed as the car in the video.

The plane has to go faster than the belt to make ground over it and get to take off speed, which means the wheels must go faster than the belt.

It's all quite simple really if you read the question.

Simples innit really

 

[doitall]

Think of it this way, "thinking outside the box ) put a push bike on a conveyor, so far so good start the belt rolling and the wheels start rotating, NOW push the bike forward, it makes no difference what speed the belt rotates at when you push the bike it moves in the direction you choose.

The conveyor is do 10 mph, get the push bike out, and you have to peddle at 10mph to stay on the belt, to cycle off the belt you need to pedal faster than 10mph.

So you are now going at 15mph but the conveyor has matched you speed so you are still stuck in the same place.

Want to try for 20mph.

 

[securespark]

No!

The plane achieves forward motion by its engine.

The wheels are out of the equation, they are freewheeling.

Your theory works ONLY when the wheels are driven by the engine, as in the car.