Airplane Flight Question - United Bimmer Community

**komodo** · 11-28-2005, 09:36 PM

This question is circulating around different forums, and the responses are always very diversified. Lets see what you guys think:

Quote:

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

The question is:

Will the plane take off or not? Will it be able to run up and take off?

witeshark · 11-28-2005, 10:17 PM

No. The plane needs high speed wind over the flight surfaces (wings) to take off. It may get lift if a hurricane comes while it's there

**xsperf** · 11-28-2005, 10:20 PM

wait, the plane is ON the conveyer, and the conveyer is moving in the opposite direction, while the plane is moving agaisnt it? thats impossible, or they are both moving at 0 mph

**xsperf** · 11-28-2005, 10:27 PM

now does the plane spin the wheels or does it use it's jet engine.. meaning is there traction between the conveyer belt and the plane?

**Spieluhr** · 11-28-2005, 10:27 PM

^^^
right. the plane has no velocity what so ever. will not take off.

**Longhairedhippy** · 11-28-2005, 10:31 PM

word.

**komodo** · 11-28-2005, 10:38 PM

I think the plane WILL take off.

Think about it, the engines are pushing the plane physically forward, thrusting through the air. The wheels have no influence on the motion, they just roll. With this setup they'll roll twice as fast, sure, but the plane will still move forward and take off the exact same.

**voca** · 11-28-2005, 10:41 PM

the conveyer isn't holding it back?

needless to say, if the plane has no velocity it wont lift. it's different if it's in motion.

**Longhairedhippy** · 11-28-2005, 10:44 PM

actually, what will happen is the bearings on the wheels will burn out and the plane will fall to the ground. moot point.

**komodo** · 11-28-2005, 10:46 PM

But what I'm saying is the jet engines on the wing thrust into the air, it doesn't matter what's going on with the wheels... they just roll.

**Longhairedhippy** · 11-28-2005, 10:48 PM

right, but as long as the wheels are on the ground, they bear the weight of the plane. as long as they bear the weight of the plane, they have traction. since they have traction on the belt, the belt pushes the plane backwards at exactly the same speed that the plane is moving forwards. the plane must make actual physical progress forward to lift off.

drz · 11-28-2005, 10:50 PM

The plane is not moving. There is no wind to lift the plane. The plane cannot take off.

**c1apton** · 11-28-2005, 10:50 PM

Plane won't fly - it's like having car on dyno. It needs airflow over wings. IE: You can throttle up plane "full tilt" with brakes on and it doesn't budge. (except ripping wings off in process)

**voca** · 11-28-2005, 10:53 PM

sure, the engines would have thrust, but the plane would still have no velocity which means no air to move over the wings which means no lift. unless the conveyer creates some kind of wind the plane is staying on the ground.

edit: I like c1aptons car on dyno visual. car has power to thw wheels but the wheels spin on tracks and the car does not gain speed.

**komodo** · 11-28-2005, 10:54 PM

Quote:

Originally Posted by c1apton

Plane won't fly - it's like having car on dyno. It needs airflow over wings. IE: You can throttle up plane "full tilt" with brakes on and it doesn't budge. (except ripping wings off in process)

But on a dyno, the wheels DRIVE the car by creating force on the ground, and the air doesn't matter much. A plane moves by creating force on the air, the wheels turning not mattering much.

And hippy, there's no way the friction is enough to stop four jet engines by simple weight and friction.... much less on a WHEEL, which is meant to alleviate friction and roll forward.