Mythbusters tonight

[fleaofsc]

Originally Posted by westexasrepublic

NO we are not saying the same thing. The plan will take off. done. if you think otherwise then you should ask a pilot, or a DR. in physics. THE END.

Yes, the plane CAN take off from the treadmill no matter what speed the treadmill is going. The question is. Can it take off from the treadmill if it is only using enough thrust to compensate for for the friction in the wheels. An too that the answer is no.

[CT_Nismo]

If this Board were a bar I can envision drunken fisticuffs over an inane issue. The deciding point of this issue is not based in physics but legal interpretation.

First, we start with the problem statement:

"A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?"

The plane has speed so we can assume it's engines are on giving rise to the speed. "Tracking the plane's speed" implies that the plane's velocity is measured against a reference point not attached to the plane or the conveyor. Logically this would be the ground. The control system then commands the conveyor to move at the same speed but in the opposite direction to the plane.

When a plane takes off under normal conditions, (take off roll) the ground underneath the plane always moves at the same speed as the plane but in the opposite direction of the plane. This apparant motion is the same as the conveyor.

Therefore the conveyor does nothing more than a runway. The plane will take off.

[Chris M]

Originally Posted by fleaofsc

The question is. Can it take off from the treadmill if it is only using enough thrust to compensate for for the friction in the wheels. An too that the answer is no.

While that's true, the original question is "Will the plane be able to take off?" The answer is "Yes".

How about we ask another question:

Will a plane be able to take off if it has a 200mph tail-wind?

[westexasrepublic]

Originally Posted by fleaofsc

Yes, the plane CAN take off from the treadmill no matter what speed the treadmill is going. The question is. Can it take off from the treadmill if it is only using enough thrust to compensate for for the friction in the wheels. An too that the answer is no.

If a plane was only going fast enough to "compensate for the friction in the wheels" then it would not be able to take off at all not even a stupid moving runway.

[Mainerunr]

Originally Posted by Zeek

Please stop saying the same thing over and over. The treadmill is going to increase in speed relative to the speed of the aircraft. Go out and buy a toy plane with wheels. Go to the gym and turn on a treadmill. While holding the plane, run it up the treadmill with the treadmill at 3mph. Next try it again at 5mph. Go ahead and try it at 10mph.

Now ask yourself, did your arm have to go faster to move the plane up the treadmill at the same rate while the treadmill was set at 10mph or 3mph? No? Well that's exaclty what will happen when the engines push the plane. The plane will move forward and the FREE SPINNING wheels will simply go faster. The engines don't have to work any harder.

read and comprehend what I'm saying then.

Originally Posted by CT_Nismo

If this Board were a bar I can envision drunken fisticuffs over an inane issue. The deciding point of this issue is not based in physics but legal interpretation.

First, we start with the problem statement:

"A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?"

The plane has speed so we can assume it's engines are on giving rise to the speed. "Tracking the plane's speed" implies that the plane's velocity is measured against a reference point not attached to the plane or the conveyor. Logically this would be the ground. The control system then commands the conveyor to move at the same speed but in the opposite direction to the plane.

When a plane takes off under normal conditions, (take off roll) the ground underneath the plane always moves at the same speed as the plane but in the opposite direction of the plane. This apparant motion is the same as the conveyor.

Therefore the conveyor does nothing more than a runway. The plane will take off.

thank you for quoting the exact question. worded that way, yes, it will take off. worded the way mountaineer was explaining it, no, it wouldnt take off.

[fleaofsc]

Originally Posted by westexasrepublic

If a plane was only going fast enough to "compensate for the friction in the wheels" then it would not be able to take off at all not even a stupid moving runway.

Dude, ur gonna wanna read mine again.... That is EXACTLY what I said.

[westexasrepublic]

but thats not even a debate, everyone knows a plane cant take off at .08 MPH. that is dumb.

[fleaofsc]

Originally Posted by westexasrepublic

but thats not even a debate, everyone knows a plane cant take off at .08 MPH. that is dumb.

Very true, but some people don't even seem to get that fact. They don't realize that no matter how fast the treadmill is going in the opposite direction it is going to take the same amount of thrust to make the plane go 0 mph relative to the ground.

[westexasrepublic]

no...................

[fleaofsc]

yes.............