stolen from canada
 

I 'stole' this from the Canada forum.
What do you lot think? (about the question, not about me stealing :) )

Re: stolen from canada
 

My husband says no. It's not generating any lift as it's not moving through the air.

Re: stolen from canada
 

No. The aeroplane is effectively still (even though the wheels are moving) and therefore no air is moving over the wings giving "lift". It is therefore theoretically sitting on the runway with the throttles wide open giving full thrust but not moving because of the conveyor belt.

Re: stolen from canada
 

But why would it sit still?
The thrust is acting against the air, not the ground.

Re: stolen from canada
 

Who gives a rats ass? I would much rather talk about your cleptomanic leanings please :)

Re: stolen from canada
 

lol.
Go start a thread about it and I'll 'fess up'. :D

Re: stolen from canada
 

Because in order to obtain air speed you first need ground speed to get lift. The Jets may well be thrusting but the aeroplane is not moving through the air and they are not sucking enough air at ground level while the aeroplane is sitting still to gain the all important 'lift".


Im winging this.

Re: stolen from canada
 

Rushman's obviously correct.

Lift on an airplane wing requires that air is moving over the lift surfaces (the curved top surfaces of the wings) at high enough speed to cause a drop in air pressure over the top surface of the wing sufficient to lift the plane.

By putting the plane on an treadmill, it's "moving" relative to the treadmill track, but not relative to the air. Therefore there will be ZERO lift, and the plane will stay right where it is.

Now a cleverer trick is to use a strong headwind to decrease the ground velocity required to take off. A good friend of mine was forced to use this trick when he landed his Cessna on a dry lake bed, only to find that he didn't have room to reach the ground speed he needed to take off. He had to wait two days until there was a strong enough head wind that he could take off into the wind and, by adding his plane's forward speed to the speed of the headwind, get enough wind speed over the wings to leave the ground.

Now he makes his money taking millionaires up in a decommissioned French Mirage fighter jet and letting them live their Top Gun fantasies!

Re: stolen from canada
 

But why wouldn't the plane move?
The plane's wheels don't drive it forward anyway, the engines drive through the air, so whatever speed the planes wheels are turning at shouldn't make any difference.

Re: stolen from canada
 

Dont tell me your mate doesnt sit there when he's alone with his thumbs on the control shouting out "rat atat atat... rat atat atat...ratat atat.....Bandits at 4 o'clock Ginger...chocs awaaaaaaaay" himself.


Though quite why he would mention Roland is a mystery.

Re: stolen from canada...
 

..brought to america, fighting on arrival, fighting for survival .... woy yoy yoy

sorry.

Comparing it to when you take a car to get an emissions test, and its lowered into the rollers and put in gear etc... the car doesn't leap out and hurtle away at 55mph.... so, I say that the plane doesn't go anywhere and doesn't lift because of no air movement. Even if it could, would it not fall back down? It can't hover.

Since the scenario begins with imagine a plane... hypothetical conveyor - i'm imagining my plane going nowhere... like this thread.

Re: stolen from canada
 

WTF are you talking about? Did you not follow a single word I wrote?

The engines would drive it forward on the conveyor belt at whatever speed they would normally drive it forward on the runway.

It wouldn't move relative to the ground because the conveyor was matching its speed in the opposite direction.

As a result, the air wouldn't be moving over the wings.

So there would be no lift.

So it wouldn't take off.

So it would stay "still" if, as the original question stated, the conveyor matched the speed generated by the engines.

Are we clear? It's not rocket science... or even aeronautics for that matter!

Re: stolen from canada...
 

Now try it with a jet engine on the roof of your car.
Think it'd stay on the rollers then?

Re: stolen from canada
 

yes I did, I just didn't agree with it :)

Re: stolen from canada
 

ROFL.

Care to explain to us all how it's going to take off?

:rofl: