Principles of flight?

[mr pad]

I voted no. If the conveyer is matching wheel speed then the plane is not moving + no wind = no lift created on wings.

Correct?

[Mr Revhead]

nope. have a read, and a think...
the key is what makes a plane move

[mr pad]

nope. have a read, and a think...
the key is what makes a plane move

An engine of sorts. But it makes no mention of one, so nothing to factor in.

[Mr Revhead]

think reeeeeal basic, how does a plane move.....

like a car? like a boat? hmmmmmmm

[pidge]

An engine of sorts. But it makes no mention of one, so nothing to factor in.

All functioning aeroplanes have either prop or jet engines.

Aeroplanes without engines are either grounded, or called "gliders"

Since the questions says the aeroplane is "ready to take off", the aeroplane having engines seems to be a reasonable assumption to make.

[mr pad]

Since the questions says the aeroplane is "ready to take off", the aeroplane having engines seems to be a reasonable assumption to make.

Well if thats the case the plane will move foward, and then fly.

Damn that wasn't so hard

[fivebob]

and fivebob pisses himself...

Indeed I am. But it's still well short of the several hundred pages I've seen on this topic on other forums (without reaching a conclusion), so keep going

FWIW I don't know the answer to this problem, or indeed if there is an answer at all. To me the definintion of the problem is in itself impossible.

In order for the belts to move the wheel must first rotate, as it is not driven directly like a car, the plane must obtain forward motion for this to happen, so no matter how fast the belt moves the wheel is always spinning faster, so the belt is instantly moving at infinite speed, while the planes wheels are spinning at infinitity plus a bit more and the plane is still moving forward.

If anything I'm of the opinion that the plane might take off, if not due to the forward motion of the aircraft, then due to the airstream created by the moving belt, or simply by having a enormous amount of tyre slip.

[RomanV]

Indeed I am. But it's still well short of the several hundered pages I've seen on this topic on other forums (without reaching a conclusion), so keep going

Bastard. :twisted:

In order for the belts to move the wheel must first rotate, as it is not driven directly like a car, the plane must obtain forward motion for this to happen, so no matter how fast the belt moves the wheel is always spinning faster, so the belt is instantly moving at infinite speed, while the planes wheels are spinning at infinitity plus a bit more and the plane is still moving forward.

I disagree. I think that the relationship between the belt and the wheel are like two gears meshed together... if you turn one gear, the other turns too at the same time.
It specifically states that the conveyor travels at the same speed as the wheels, not a fraction faster or slower.

The belt would not travel at infinite speed... as the belt (according to the rules) only travels at the speed of the plane(relative to the ground) times 2. Well the belt WOULD travel at infinite speed, but only if the plane was too.

[mr pad]

so no matter how fast the belt moves the wheel is always spinning faster, so the belt is instantly moving at infinite speed, while the planes wheels are spinning at infinitity plus a bit more and the plane is still moving forward.

If anything I'm of the opinion that the plane might take off, if not due to the forward motion of the aircraft, then due to the airstream created by the moving belt, or simply by having a enormous amount of tyre slip.

Thats where I was unsure. The question is too vague for a positive answer. You can say "if this is, and it could that" but finding a definite answer seems.... tricky It seems in theory, that if this rule was applied using real world physics, well again it depends on how fast the wheels/conveyer are moving, and if moving at infinity, the plane would not take off, less like fivebob said, it was from the huge currents of air created by the belt, which can be ruled out due to the fact the question states there is no air flow. So I still say no. *head explodes*

[Mr Revhead]

i still say yes.

because its the air that is important..... there is nothing pushing against the however many lbs of thrust being created by the engines... so it HAS to move. it moves relative to the air, thats why ground speed isnt measured in a plane, its airspeed that matters

the wheels and conveyer belt are actually seprate

think of a toy car on a conveyer belt.... if you push it it moves.
now think of your finger as the thrust.....

not quite accurate as far as the speed of the wheels go, but the principle is the same

[method]

Arh ok...I will succum to the others thinking...its my training I tell you....civil enginneers dont have to worry about wheels and stuff...just forces/elements...

Where did you study?

[method]

I guess there are two answes,

Theoretically Yes, it takes off but practically it isnt possible. The belt would break, or the wheels would spin so fast they would break up causing the plane to hit the belt and desintagrate or something crazy and thats IF you could build a belt like that in the first place

[malc]

think of a toy car on a conveyer belt.... if you push it it moves.
now think of your finger as the thrust.....

That would not be the case in this case, because on the large conveyor the speed of the wheels is being matched at all times. If you gave the car a shove on a conveyor with a constant speed then the wheels of the car would speed up and the car would move forward. But with this large conveyor the wheels would not be able to speed up relative to the surface below it, after all it is being matched at all times.

Push matchbox car on treadmill against the motion of the belf. Can you push the car from one end to the other?

like above, it would move forward, and that is because your normal treadmill moves at a constant speed. It makes no odds whether the car is pushed very quickly or with a huge amount of thrust.
For something to move forward it must gain traction or be moving faster than the surface below. In the case of the plane, its forward speed is transfered through its wheels.

So if a plane is cruising at 200kmh flying along above ground,
and they they go full throttle,
how does the plane accelerate without the wheels on the ground.

That is because the plane got moving in the first place. It has equalled its drag, and bettered its weight.
I dont think the plane on the conveyor would move relative to the air around it or the ground beyond the conveyor, so it cannot overcome those forces.

[RomanV]

The foward motion of the plane is NOT transferred through the wheels.
As the wheels are not 'driven' like on a car.
A car moves foward by pushing against the ground... if the ground is moving backwards at the same speed as the wheels, then it will sit still.

The wheels on a plane merely reduce the friction between the plane and the ground....

I think that the 'toy car and a piece of paper' idea is the best way to demonstrate what happens.

Put the car on the paper, and push the car one way, and pull the paper under it at the same speed in the opposite direction.
The car moves, the paper moves, and the wheels move at twice the speed.

Your finger pushing the car is EXACTLY the same as if jet engines were propelling it.... it is an EXTERNAL force, that makes the wheel speed irellevant.

[Mr Revhead]

ah but you are forgetting the thrust. it HAS to move.

as i said my example wasnt 100% accurate to the original question, but its close enough to display my point.

when you get right down to it.....
its making thrust
whats conteracting that thrust?
NOTHING
therefore it moves.


the wheels and the belt are superflorus to the question.
as ppl have already stated whats important it the air.

a lot of you are still thinking as if the wheels make the plane move, they are only there to reduce friction, they are really only bearings

[pidge]

Newton's Three Laws of Motion

I. Every object in a state of uniform motion remains in that state of motion unless an external force is applied to it.

II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. (Note: Acceleration and force are vectors (Direction and Magnitude). The direction of the sum of the force vectors applied to an object is the same as the direction of the acceleration vector.

III. For every action there is an equal and opposite reaction.

If you do not understand those, you cannot solve this "puzzle".

(As many of us have said) The only significant force on the aeroplane is the thrust from the engines. Therefore the aeroplane will accelerate along the converyor belt runway and take off.

[RomanV]

Im not entirely convinced that Fivebob believes what he posted, as I think he is trying to be controversial, and doesnt want the debate to end.

After all, he DID post this up for his own twisted entertainment.

And besides, who is stupider?
The people that think the entire force of the planes engines is transmitted as a rotational/frictional force through the wheels,(Or what ever physics concept they cant grasp at the time)
OR the people who keep on trying to talk sense into these people?

I think thats the real question here.

[Mr Revhead]

well done dave, i think you just called everyone stupid

[RomanV]

Except for me, cos I figured it out.
I'm S-M-R-T smart.

I bet this question was initially posed by a psychologist, who was interested in studying the conflict and aggrovation that arises when people fail to understand simple concepts.

[Mr Revhead]

well i did pose the question int he smoko room and two mechs did get quite wound up about it...