Aircraft on a conveyor

[Infidel]

Wheels have got sweet FA to do with how a plane takes off they are only the means to get the air flow over the wing in order to creat lift, if it worked don't you think they would have employed it on aircraft carriers as opposed to the catapult system.
Any how rotors work.

 

[doitall]

To prove the point stick the plane on a rolling road the same as found in a garage for testing cars.

not the same as a rolling road would remain stationary as no tractive force is sent through the wheels

the only sums you need to do is thrust verses air resistance with rolling resistance bearing friction added on

If the wheels are traveling at 1000mph and the conveyor is traveling at 1000mph in the opposite direction, the plane will be stationary BA.

Therefore no air speed and no take off.

 

[cantaloup63]

I hate this topic and always have done whenever and wherever it has emerged

 

[Deleted member 63160]

Seeing as the plane has to acheive adequate air speed regardless of
what the wheels are doing, wouldn't the treadmill/conveyor belt need
to the length of a runway? Say 7 or 8 thousand feet for an airliner?

 

[cantaloup63]

Now what would be interesting would be if system started from stationary and the treadmill accelerated backwards to match what the forward speed created by the thrust of the engines would have been (thus making the plane stationary from an observer standing on the ground), and then the treadmill instantaneously stopped.

 

[Norcon]

Doitall wrote

the wheels turning at 500 miles an hour on a conveyor

How do wheels turn at 500 mile per hour?

"Mile per hour" is distance travelled. Wheels turning is "rpm".

 

[cantaloup63]

Doitall wrote

the wheels turning at 500 miles an hour on a conveyor

How do wheels turn at 500 mile per hour?

"Mile per hour" is distance travelled. Wheels turning is "rpm".

Hmm, if the wheels turned at rpm then their circumference would "travel" a distance since they aren't slipping. So the two are synonymous

 

[sooey]

I hate this topic and always have done whenever and wherever it has emerged

Couldn't agree more, it's been done to death time and again on here.
Notice it was megabore who brought it back up as one of his first "contributions" since coming back.

 

[Deleted member 63160]

Now what would be interesting would be if system started from stationary and the treadmill accelerated backwards to match what the forward speed created by the thrust of the engines would have been (thus making the plane stationary from an observer standing on the ground), and then the treadmill instantaneously stopped.

Remember the wheels aren't driven. Think of a sea plane.

 

[cantaloup63]

Remember the wheels aren't driven. Think of a sea plane.

You misunderstand my point. The thrust of the engine would cause the plane to move forward regardless of what the wheels were on. If the treadmill bagan to move backwards (by a separate motor unrelated to the plane) to match that speed - in effect creating an equivalent "headwind" effect, then the plane would be seen to stand still. We are pretty much in agreement on this point. The question I have is what would happen of the treadmill suddenly stopped instantaneously?

 

[cantaloup63]

I hate this topic and always have done whenever and wherever it has emerged

Couldn't agree more, it's been done to death time and again on here.
Notice it was megabore who brought it back up as one of his first "contributions" since coming back.

And yet, completely hypocritically of me, I' appear to have been drawn into it

Right, no more!!!

 

[Deleted member 63160]

Remember the wheels aren't driven. Think of a sea plane.

You misunderstand my point. The thrust of the engine would cause the plane to move forward regardless of what the wheels were on. If the treadmill bagan to move backwards (by a separate motor unrelated to the plane) to match that speed - in effect creating an equivalent "headwind" effect, then the plane would be seen to stand still. We are pretty much in agreement on this point. The question I have is what would happen of the treadmill suddenly stopped instantaneously?

How long is this treadmill just out of interest?

 

[cantaloup63]

How long is this treadmill just out of interest?

Two feet 7 inches, but it does have it's surface in line with the ground around it, so there's no step up nor down to terra-firma.

 

[big-all]

The question I have is what would happen of the treadmill suddenly stopped instantaneously?

the plane would continue untill all the kinetic energy has dissipated through wind resistance and bearing friction

when i was a train driver we would often coast for 10miles if ahead off schedule with passenger trains dependant on gradient the speed would drop from 75 to around 30mph

indeed trains can travel for many 10s off miles with only momentum and a slight down hill grade
a train on the level doing 30mph could travel around 10 miles before coming to a stand

 

[imamartian]

I used to think the plane would not take off.... but i'm now inclined to think it would take off.

If you miniaturise the problem and use a toy plane on a treadmill, and replaced the plane's thrust with my finger pushing it, i'm sure i could move the plane forwards.... i just can't picture what would be happening with the wheels....

Or if, in the 'real' problem, instead of the engine's thrust you had a chain attached to the nose of the plane and the other end to a giant winch... if you turned the winch, it's guaranteed that the planed would move forwards... again i can't work out what's happening with the wheels.

Firstly, am i right to replace the thrust with an external 'push' or 'pull'?

Secondly, is the wheel v conveyor an impossible situation perhaps, in a similar way perpetual motion is?