A question...

[asdf1234]

Originally posted by BLLDOGG:
well, until the plane is air born, the plane needs the wheel for movement. so if the plane moves forward 1mph, the treadmill is moving backwards instantaniously 1mph which would cuase no movement.

Wrong, it would only cause the wheel to move at 2mph, and the plane still at 1mph.

[3.4 slow to go]

does a plane taxing or taking off do so on a magic air cloud? how does a plane move around on the ground? wheels.

[BLLDOGG]

Originally posted by asdf1234:
</font><blockquote>quote:</font><hr />Originally posted by 3.4 slow to go:
wtf are you talking about? the plane is just going to sit there w/it's wheels spinning, no matter how much thrust is used, as the treadmill will go that much faster to keep the wheels in place

The thrust isn't coming from the wheels, its coming from the prop. The wheels are not doing anything that affects the plane from moving. They're spinning, yes, but as the prop pulls the plane the wheels will just spin faster, why would a spinning wheel stop the plane from traveling? </font>[/QUOTE]because the wheels are still sitting on the treadmill being pushed back at an equal speed

[98Camaro3.8]

Originally posted by 3.4 slow to go:
wtf are you talking about? the plane is just going to sit there w/it's wheels spinning, no matter how much thrust is used, as the treadmill will go that much faster to keep the wheels in place

Simple physics says that if there is a force pushing the plane forward, there absolutely must be countered by an equal force in the opposite direction for it to stand still. The rolling friction from a wheel at a takeoff speed is wayyy lower than this.

If the treadmill was going at 1,000 mph (and the tires didn't blow), there would be enough friction to keep the airplane still (or more...and therefore move it backwards). But that's a different question. At the same speed as the airplane, there won't be enough of a force to keep it in the same location.

Originally posted by vroom-chirp:
aircraft engine= 1000lbs of thrust
tread mill= 900mph
we're still not going any where...

900 mph isn't a takeoff speed. See above paragraph.

[asdf1234]

Originally posted by 3.4 slow to go:
does a plane taxing or taking off do so on a magic air cloud? how does a plane move around on the ground? wheels.

Did the question have anything to do with taxing? It doesn't use the wheels to take off, it uses the propeller. The wheels are just along for the ride.

[3.4 slow to go]

Originally posted by asdf1234:
</font><blockquote>quote:</font><hr />Originally posted by BLLDOGG:
well, until the plane is air born, the plane needs the wheel for movement. so if the plane moves forward 1mph, the treadmill is moving backwards instantaniously 1mph which would cuase no movement.

Wrong, it would only cause the wheel to move at 2mph, and the plane still at 1mph. </font>[/QUOTE]sooooo, the wheels move at twice to speed of a plane, and are still connected to teh landing gear.......because????? sticker charged?

[98Camaro3.8]

Originally posted by BLLDOGG:
because the wheels are still sitting on the treadmill being pushed back at an equal speed

But look at it this way. The treadmill isn't pushing the wheels. It's rolling under the wheels. It's causing the wheel to roll. There is a little bit of friction caused by the weight of the airplane and the bearings and such, but that is not enough force to fight the thrust.

[asdf1234]

The wheels are moving twice the speed of the plane because of the treadmill moving in the opposite direction.

[98Camaro3.8]

Originally posted by 3.4 slow to go:
sooooo, the wheels move at twice to speed of a plane, and are still connected to teh landing gear.......because????? sticker charged?

Airplane moves forward at 10 mph. Treadmill moves at 10 mph the other way. 10 + 10 = 20. As far as the wheels are concerned, the ground is stationary and the plane is moving at 20 mph.

[3.4 slow to go]

by that logic, a car on a dyno is actually going twice as fast as what the speedo says it is

edit: my bad, the car isn't moving, the tires aren't spinning????

[BLLDOGG]

Originally posted by 98Camaro3.8:
</font><blockquote>quote:</font><hr />Originally posted by BLLDOGG:
because the wheels are still sitting on the treadmill being pushed back at an equal speed

But look at it this way. The treadmill isn't pushing the wheels. It's rolling under the wheels. It's causing the wheel to roll. There is a little bit of friction caused by the weight of the airplane and the bearings and such, but that is not enough force to fight the thrust. </font>[/QUOTE]well when it says match the speed of the plane, is that limited to the same speed or if you double the speed of the treadmill compared to the plane, would it hold then?

[vroom-chirp]

forget the plane for just a second,
if i strap a jet engine to my geo metero and put it on a tread mill that measures the speed at wich the object placed on it is traveling to cancel any foward movement, will the geo run off the tread mill ?!?

[camaro_speedemon]

Originally posted by asdf1234:
You all are assuming that an airplanes wheels are working the same way as your f-body's wheels are.

An airplane is propelled by a propeller, the wheels are just along for the ride.

If you were to put on a pair of rollerblades and stand on a treadmill that was moving at 100mph, would you go anywhere? No, you would stay still. Now if somebody were to stand behind you and push you forward, you would move forward. Not faster than 100mph, but at the speed of which you were pushed forward. The airplane is being pulled by the propeller. No matter what speed the treadmill is moving, or what direction, the airplane would still move forward as much as it wanted to until it reached speeds able to sustain flight.

OK, That makes sense, but it still wouldn't take off. As soon as the plane reached the end of the treadmill, the wheels would be moving increadibly fast in reverse, and make contact with the non-moving pavement. That in combination of the forward motion of the plane, would probably cause them to blow out from the from the friction. [img]tongue.gif[/img]

[asdf1234]

Originally posted by 3.4 slow to go:
by that logic, a car on a dyno is actually going twice as fast as what the speedo says it is

We aren't talking about a car...

[98Camaro3.8]

Originally posted by BLLDOGG:
well when it says match the speed of the plane, is that limited to the same speed or if you double the speed of the treadmill compared to the plane, would it hold then?

We're getting there!

Eventually, yes it will. Eventually they will be going so fast that they will create enough friction to fight the thrust and keep the plane stationary. There's no fighting that.

If the question said the treadmill moved at 1,000 times the speed of the plane in the opposite direction, the plane wouldn't fly. I don't know what number needs to go there, but it's gonna be big.

But as per the question, as the same speed as the plane, there isn't enough friction.