conveyor belt and plane answered at last ??

[Norcon]

crank39 wrote

but the question stated the wheel speed remained equalised with the conveyor,

And therein lies part of the flaw in the question. Is the wheel speed rpm or measured in mph from a ground fixed point?
Is the conveyor speed rpm or measured from a ground fixed point?
Is it a proper conveyor or a lash up like in the mythbusters video?

if the plane moved forward the wheels would be travelling forward faster than the conveyor is moving

Depends on how the above questions are answered.

 

[big-all]

SORRY I MENTIONED IT

 

[rjm2k]

And therein lies part of the flaw in the question. Is the wheel speed rpm or measured in mph from a ground fixed point?
Is the conveyor speed rpm or measured from a ground fixed point?
Is it a proper conveyor or a lash up like in the mythbusters video?

Depends on how the above questions are answered.

I don't think the above matter, the question is not a trick to catch you out on your interpretation of the type of conveyour belt or its operator, it's a theoretical question which is asking if a plane with its thrust on can make no forward motion (due to its motion being cancelled by the belt), will it take off?

The situation is no different than when a pilot does an engine test by leaving the brakes on and throtteling up, there is no airflow so no lift and no flight.

 

[GasBod]

An aircraft is standing on a very long runway that can move (a conveyor belt). The aircraft moves in one direction, while the conveyor belt moves in the opposite direction. This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels, but in the opposite direction. There is no wind. The pilot begins to add thrust to the engines...

Will the plane ever take off?

Of course it will take off

 

[doitall]

No it wont.

If a tread mill is travelling at 5mph, you jump on you have to walk 5mph to keep up with it. to walk up the belt you have to go faster than 5mph.

The plane is the same in a fixed position the wheels are turning the same rate as the belt is travelling, to take off the wheels need to go faster than the belt.

 

[AronSearle]

No it wont.

If a tread mill is travelling at 5mph, you jump on you have to walk 5mph to keep up with it. to walk up the belt you have to go faster than 5mph.

Planes don't have legs, they have wheels. Not sure why you persist in comparing wheels to legs, when a skateboard/Rollerblades would be a correct analogy, both of which mean you can stay stationary/move, whilst the wheels do what they like.

The plane is the same in a fixed position

The question clearly states the plane is moving, ignoring the phrasing of the question, physics would allow the plane to move.

Either way you are busted, why persist in making yourself look silly?

the wheels are turning the same rate as the belt is travelling, to take off the wheels need to go faster than the belt.

No.

The ball bearings inside the wheel will go twice or more than the speed of the treadmill belt. but the wheel will match whatever they conveyor is doing.

You really don't seem to understand how a ball bearing free-wheel works.

 

[Norcon]

And therein lies part of the flaw in the question. Is the wheel speed rpm or measured in mph from a ground fixed point?
Is the conveyor speed rpm or measured from a ground fixed point?
Is it a proper conveyor or a lash up like in the mythbusters video?

Depends on how the above questions are answered.

I don't think the above matter, the question is not a trick to catch you out on your interpretation of the type of conveyour belt or its operator, it's a theoretical question which is asking if a plane with its thrust on can make no forward motion (due to its motion being cancelled by the belt), will it take off?

The situation is no different than when a pilot does an engine test by leaving the brakes on and throtteling up, there is no airflow so no lift and no flight.

I beg to differ. How you intrepret the question will sway your answer either way.

If it was a simple question like.... "will a plane take of on a conveyor belt?" then the answer is yes. Add in the other variables and the answer is debatable imho.

 

[doitall]

The question clearly states the plane is moving, ignoring the phrasing of the question, physics would allow the plane to move.

How can you ignore the phrasing of the question, or is that the only way you can get the plane in the air.

 

[AronSearle]

How can you ignore the phrasing of the question, or is that the only way you can get the plane in the air.

Errr, the question as posted, says the plane is moving.

Moving = take off.

As to "ignoring the phrasing of the question", that is simply to state that most people would get the gist of the question without hiding behind pedantic wording.

You have now resorted to ignoring various parts of posts, and nitpicking out of context what they say and adding smilies, pretty clear you now know you are wrong, but are just to embarrassed to admit what a prize banana you have been.


+ +infinity no returns.

 

[doitall]

Prize banana, much better than being a complete Lemon.

 

[peterperfection]

The wheels of a aircraft have NO drive.
The drive of a aircraft is supplied by the thrust of the engines.
Therefore- it is as if the aircraft wheels are on a ice field with no grip.
YES the aircraft WILL take off. Unless of course a drunken pilot puts his foot on the brakes.

Similar/ish to a rolling road on MOT test.

The wheels simply hold up the fuselage off the ground.

Also- consider a seaplane. NO wheels-just 'skids'. and minimum resistance.
The ONLY thing that keeps a aircraft on the ground is its weight.
Gravity too.
Once engine thrust is applied- if there is NO wind resistance- absolutely nothing can stop the aircraft moving forward.
Think about it.

 

[peterperfection]

Lateral thinking here- regarding the question . - WILL the plane take off' ?. Not- CAN the plane take off.
Common sense says- that the plane will obviously move forward at a great speed than the conveyor - especially after the wheels have left the ground.
However- 'blown tyres' come to mind- and a take off would be aborted.

I stick by my first post though .

 

[doitall]

The wheels of a aircraft have NO drive.
The drive of a aircraft is supplied by the thrust of the engines.
Therefore- it is as if the aircraft wheels are on a ice field with no grip.
YES the aircraft WILL take off. Unless of course a drunken pilot puts his foot on the brakes.

Similar/ish to a rolling road on MOT test.

The wheels simply hold up the fuselage off the ground.

Also- consider a seaplane. NO wheels-just 'skids'. and minimum resistance.
The ONLY thing that keeps a aircraft on the ground is its weight.
Gravity too.
Once engine thrust is applied- if there is NO wind resistance- absolutely nothing can stop the aircraft moving forward.
Think about it.

At this rate I'll have a sack full of turnips and sweed to keep me going well into the new year.

We won't comment on the field of ice as clearly the poster has not read the question or just doesn't understand it.

Lets take the rolling road the car is doing 50mph in the garage, how many miles does it travel in say 1hr or is it staying in the same spot.

Next the plane isn't on the ground, it's on a conveyor belt and the wheels are turning exactly the same speed as the conveyor belt so just like the car there's no forward or backward movement. Note; if the car wheels go faster than the rolling road it will go through the garage wall.

the only thing that keeps the plane on the ground is it's weight and gravity

I assume you are saying it can't fly or does it get lighter, magically.

Engine trust is applied and absolutely nothing can stop it moving forward, read the question again for the plane to move forward the wheels have to turn faster than the belt, Rolling road again.

Nothing to think about, it cannot take off as it needs an air flow.

 

[joe-90]

Either it takes off with the wheels turning at twice the speed they would turn on a runway - or the question makes no sense in our universe.

Take your pick. It either takes off or it doesn't move because the question is invalid. Take your pick.

 

[Mw Roofline]

No it wont.

If a tread mill is travelling at 5mph, you jump on you have to walk 5mph to keep up with it. to walk up the belt you have to go faster than 5mph.

The plane is the same in a fixed position the wheels are turning the same rate as the belt is travelling, to take off the wheels need to go faster than the belt.

Lol, planes don't have legs.

The easiest way to understand all this (I haven't read all the last trillion pages so someone may have already mentioned it) is imagine you are the plane on roller skates and the runway is one of those check-out supermarket moving things but it's in reverse mode.

You stand still with me next to you standing on the floor and when the belt starts to move, you also start to move backwards. I stop you from moving backwards as I'm right next to you with my hand on your back stopping you still. let's say the belt is going 10 miles an hour.

Marjorie the check out lady cranks up the mph to 20, 30 and 50mph. Your wheels are spinning like crazy but you are stood still still because I'm applying a bit of pressure to your back.

Then marjorie cranks it up to 250mph and all it takes is a gentle push of my hand and I can push you forwards along the conveyor which is doing 250mph, just because it's going faster doesn't mean there is any more pressure on my hand. I start to push you a little more and you move forward easy as pie. It doesnt matter how fast the belt is moving because whatever speed is happening is just getting absorbed up by the wheels going round and round.

Now subsitute my hand for an engine, attach a few wings to your arms and you'll 100% take off.