Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[goblolo]

This forum has showed for me that we have here a lot of men with above average mental abilities (sorry for my English). And I have a challenge for you!
I want to test it on a simple question concerning physics and logics. The question itself is a meme and I want you to think it yourself, without using google.

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 the opposite direction). Can the plane take off?

So, what do you think of it?

[IronyOwl]

Huh, that is an interesting question. I really don't know enough about plane mechanics to say, but I'm guessing that since the plane is stationary relative to the air around it, and that's the stuff it's trying to fly in, it wouldn't be able to.

[Andrew425]

Mythbusters says yes.

Personally I haven't been able to understand how a plane lifts without generating any air flow under the wings. Unless the propeller has enough power to do it.

[Criptfeind]

Mythbusters says yes.

Personally I haven't been able to understand how a plane lifts without generating any air flow under the wings. Unless the propeller has enough power to do it.

How big and fast of a conveyer does it need?

A big and fast enough one would be able to create enough wind current I would think. Although I am almost certainly wrong seeing as how I know almost nothing about this sorta thing.

[lordcooper]

Aircraft do not require friction with the ground to accelerate in the same way that a car or bicycle does.  It would accelerate at almost exactly the same rate as it normally and take off with ease.

[Andrew425]

Aircraft do not require friction with the ground to accelerate in the same way that a car or bicycle does.  It would accelerate at almost exactly the same rate as it normally and take off with ease.

I think the question has the conveyor belt moving so that it can't accelerate. In its essence I think the question is: can a plane take off without moving? If there is no horizontal movement can it provide enough vertical energy to beat gravity ( if the answer is yes, then it will fly. If not it won't.

At least thats how I see it.

[lordcooper]

If it can't accelerate then nether the plane nor conveyor belt would move in the slightest.

[Frumple]

'Course, it kinda' depends on the plane. We've got VTOL machines, and they'd pretty much definitely be able to lift off in that scenario

[Criptfeind]

I think accelerate moves faster, not turn on engines.

[Sir Finkus]

Yes, all of the thrust of an airplane is from the jet or propeller.  The wheels would just turn twice as fast.

[SalmonGod]

I also thought that lift came from air flow beneath the wings... but it sounds like I'm wrong?  It's weird to imagine a plane that's stationary except for spinning wheels suddenly take off.

[Ogdibus]

.

[miauw62]

If the conveyor matches the speed of the plane, the plane will not move.  If the plane doesn't move, then neither does the conveyor.  If the conveyor isn't moving, it can't slow down the plane. x3

The plane doesn't need speed, it needs lift.  If there isn't enough air moving across the lift surfaces (not necessarily the wings), it won't fly.  If there is enough, it will... I think.  In order to do physics, we would have to account for many more factors than the scenario describes, and probably some engineers.

Yeah, but to get lift it needs speed, usually. There's probably an exception somewhere.

[Criptfeind]

I think Finkus sounds right.

[PanH]

plane speed != plane's wheel rotation (because the belt conveyor is there)

At no speed, the belt conveyor will not function.
With a little speed, the conveyor will slow down the plane speed (and thus itself), while the thrust of the plane will remain the same.

So, yes. Theoretically true.