This old chestnut

[roofman]

No movement of forward air over and under the wings then absolutely no lift is created..much the same as you can push the throttles forward 100% with the brakes on or wheels tied and the aircraft will not lift except a small raise of the rear from air going over the tail wings.

 

[Pete.]

You know that the conveyor matches the wheel speed. Therefore the wheels must be turning. Therefore there must be thrust from the engines to advance the plane thereby causing rotation of said wheels.

The only thing you know is that the conveyor is designed to match the wheel speed. They might both be zero.

 

[RWD3M]

I can't believe you lot are still debating this!! Quiet news day?

 

[Seadog]

They will be at zero, with no thrust. However the question is "Could it take off?"

 

[fizzy]

In a strong wind a plane can take off almost vertically - or land the same.

 

[AVI_8]

I can't believe you lot are still debating this!! Quiet news day?

Haha

 

[Pete.]

They will be at zero, with no thrust. However the question is "Could it take off?"

Actually it's "Can the aerpolane take off?"

That depends on if it's cleared to or not

 

[E T]

The thrust of the plane engines against the air provide the forward motion. It does not matter what is below the wheels, be it a moving conveyor or fixed runway. The plane will take off.

 

[KemppiFrog]

After reading this f'twitery, I went back and re-read the original question. It will take off. The conveyer matches the speed of the wheels, so it doesn't matter about what speed. As said, the aircraft will only move via it's engines( unless a super powerful tug), ignoring tyre speeds and wheel bearings (not mentioned in the question) so, once it attains enough lift, it leaves the conveyer belt and give the undercarriage a rest, along with very worried stowaways hiding in the wheel wells.

Going back a bit, Our J-3 Piper cub was slightly pedestrian with its 65 hp donk and wandered the skys at a gentle pace. Couple of times, on arriving back at the strip,if the wind had got up, one needed people to grab the struts to hold us down, as when the tail dropped, the wings decided that there was enough lift to set off again. 'cors, at much lower speeds that a 747.

 

[sg66]

Wheels are irrelevant, if the plane has thrust its airspeed that's the factor for lift not what the wheels are doing, wheels will just be going twice as fast

 

[Barking Mat]

Wheels are irrelevant, if the plane has thrust its airspeed that's the factor for lift not what the wheels are doing, wheels will just be going twice as fast

Yep, the increase in airspeed over / under a wing, is what gives lift, hence acceleration on take off.

Vertical take off would be different.

No, don't think it could.

It would be like a jet engine on a test bed.

 

[Seadog]

It would be like a jet engine on a test bed

Not really. That engine is fastened to terra firma.

 

[Barking Mat]

Not really. That engine is fastened to terra firma.

But the conveyor belt will match any speed, so therefore it will never advance enough to move.

 

[Seadog]

It matches the speed of the wheels. They are not driving the plane, they're just there to provide a low friction support system to allow the thrust to propel it

 

[Other Daniel]

 

[Pete.]

The question is either compiled by a drunk or very cleverly badly worded. If it was presented in a coherent way there would be no debate

 

[Dr.Al]

As long as the aircrafy can reach its its rotation speed it will take off.

... and the editor's decision is final on this.

Sorry, couldn't resist plagiarising "David Gunson". If you've not listened to his speech: go and listen now: it's brilliant.

 

[rtcosic]

The question is either compiled by a drunk or very cleverly badly worded. If it was presented in a coherent way there would be no debate

I thought it was very tightly and clearly worded:

exactly match the speed of the wheels, moving in the opposite direction.

So the aircraft is stationary.

So there is no airflow over the wings.

So there is no lift.

So nothing happens.

Now let's resurrect the old chestnut of the 3 tonne wagon with a 1 tonne load of budgies and the bridge with a 3 tonne weight limit.
If the driver bangs on the side of the wagon to get all the budgies flying then crosses the bridge will the bridge weight limit be exceeded?

Edit: phat phinger error correction.

 

[Barking Mat]

I thought it was very tightly and clearly worder:

exactly match the speed of the wheels, moving in the opposite direction.

So the aircraft is stationary.

So there is no airflow over the wings.

So there is no lift.

So nothing happens.

Now let's resurrect the old chestnut of the 3 tonne wagon with a 1 tonne load of budgies and the bridge with a 3 tonne weight limit.
If the driver bangs on the side of the wagon to get all the budgies flying then crosses the bridge will the bridge weight limit be exceeded?

I was just about to start discussing momentum.

Thank you.

 

[rtcosic]

Half em vee squared?
Law of Conservation thereof?
Something else entirely? Such as Thread Drift?