Airplane on a Conveyor conundrum

[Slugsie]

thats the thing. if the conveyor ever moved then this would have a force on the airplane. but since the equasion works out that the conveyor never moves at all, then there wont be any force on the plane and it will take off.
its not a flaw in my thinking. its a theory your completely misunderstanding

It is a flaw in your thinking, because you appear to be deliberately mis-interpreting both the meaning and the intention of the question. But it's also irrelevant, because as has been explained over and over again, no matter how the conveyor moves (forwards, backwards, or stationary), the aircraft will still take off.

[dieselboy]

Sorry Slugsie but that website contradicts itself:-

In number '2)' of the interpretation of the question he gives a 100% bet you life answer as 'No'. Then in 'B' of his core facts states 'relative to the ground' that it will take off. Well '2)' states it being 'relative to the ground' - so a contraditon occurs.

The only answer is that given by the very first post (Trev I think), as long as it is a normal airplane and not a jump jet (Harrier). As there's no tail or head wind the air is still in relation to the ground (in relation = linked), air and ground do not move.

During take off the engines are needed to overcome the friction created by the wheels on the ground to gain enough wind speed over the wings so lift can occur to overcome the gravity. Even if a jet engine is burning at full throttle it cannot move forward on a conveyor belt which moves at a speed matching the force created by the engines - and hence cannot get any air passing it's wings. I could stand next to the plane on the ground and talk to the pilot while all this was going on (just as a car does on a rolling road in the garage).

It just is not possible!!! haha I can't believe it's even being discussed lol.
Again - without enough 'lift' the plane cannot overcome gravity! To get lift you need air passing over the wings! In this scenario there is no wind doing that.

you are completely correct my friend. in a perfect situation, what you said will happen exactly how you said it.
but in real life i think it is impossible to get this perfect situation, and its what i think slugsie is getting confused about.

regardless, in his question, he doesnt specify that the conveyor speed is measured from the fixed point in the ground also. therefore i assume that it is taken from the plane itself, as the question states:

The conveyor belt is computer controlled such that its speed is always the same as that of the aircraft - only backwards

therefore the equasion works out that the conveyor doesnt actually move at all, because it has the same speed as the ground, which is also not moving.
therefore the plane has no reverse force acting on it, and it is able to take off.

[dieselboy]

It is a flaw in your thinking, because you appear to be deliberately mis-interpreting both the meaning and the intention of the question. But it's also irrelevant, because as has been explained over and over again, no matter how the conveyor moves (forwards, backwards, or stationary), the aircraft will still take off.

dont get the hump slugsie, read my post befoe this one

[Slugsie]

regardless, in his question, he doesnt specify that the conveyor speed is measured from the fixed point in the ground also. therefore i assume that it is taken from the plane itself, as the question states:

You therefore make an incorrect assumption, and despite being told that many times, you persist with your incorrect assumption. We have even agreed in previous posts that it isn't reasonable to measure the speed of the two principles from different points. Yet still you persist with your incorrect assumption. The questions states that the conveyor moves at the same speed as the plane, NOT that the conveyor moves away from the plan as fast as the plane moves away from the conveyor.

But again, and this is my last on the subject, it is irrelevant. The forward/backward speed of the conveyor will have no influence on the ability of the aircraft to gain airspeed and fly.

Roll on lunchtime.

[Sancho]

You must never delete this thread.

It is a shining example of the human refusal to accept the facts and aimlessly keep arguing a moot point for the sake of looking clever. This should be preserved for future generations.

[Slugsie]

You must never delete this thread.

It is a shining example of the human refusal to accept the facts and aimlessly keep arguing a moot point for the sake of looking clever. This should be preserved for future generations.

Well, I won't delete it, but I will be locking it.

[dieselboy]

You therefore make an incorrect assumption, and despite being told that many times, you persist with your incorrect assumption.
well why didnt you make yourself clear from the start.
and since you didnt, it leaves more questions open.

We have even agreed in previous posts that it isn't reasonable to measure the speed of the two principles from different points.
then if this is the case, then the plane would not take off because of the reverse force acting on it from the conveyor

Yet still you persist with your incorrect assumption.
there is nothing in the first post to say im incorrect at this stage.
The questions states that the conveyor moves at the same speed as the plane,
ive always said the conveyor moves the same speed as the plane. you add the two together somehow
NOT that the conveyor moves away from the plan as fast as the plane moves away from the conveyor.

But again, and this is my last on the subject, it is irrelevant. The forward/backward speed of the conveyor will have no influence on the ability of the aircraft to gain airspeed and fly.
IF, and i mean IF, the conveyor were to move, then it would influence the airplane and prevent it from moving at all, therefore not letting it acheive an airspeed required to take off.
Roll on lunchtime.

.

[Slugsie]

Well, I won't delete it, but I will be locking it.

Does anyone know of a way to download the thread in one go just like you can do with PMs?

[Slugsie]

.

Did you watch the videos? Did you read the web-page I posted. It's all made perfectly clear.

[TonyN]

therefore the equasion works out that the conveyor doesnt actually move at all, because it has the same speed as the ground, which is also not moving.
therefore the plane has no reverse force acting on it, and it is able to take off.

?????????

At the risk of getting sensible in the thread,

The trick part of the question is right at the beginning of the thread, the conveyer belt needs run backwards, try to move the plane backwards, to prove it dosn't matter.

If the plane gained speed through air to generate lift by powering its wheels like a car, then its easy to make the go nowhere by running the belt backwards at the same speed the wheels are running forwards.

But because its getting thrust, against air, from its engines, its negates any holding back effect of the conveyer belt can give on its wheels. In theroy drag on the wheel bearings and weight of the plane on the wheels gives the belt some help, like putting the brakes on would slow the plane down. but it could never practailly be enough to stop normal plane engines pushing the normal plane forwards on normal plane wheels, wether its on a backwards running belt or not, on this planet.

[dieselboy]

You must never delete this thread.

It is a shining example of the human refusal to accept the facts and aimlessly keep arguing a moot point for the sake of looking clever. This should be preserved for future generations.

thing is, there is no facts. there is only two outcomes here, and each one a different result.

fact 1, if the conveyor provides a force, then the plane must match that force plus more to start accelerating.

fact 2, if object 'A' (plane) moves away from another object 'B' (ground or conveyor) at a given speed, then object B is also moving away from object A at the same speed.

[Antshiel]

But no-one said it was on this planet!!

[Chillitt]

then if this is the case, then the plane would not take off because of the reverse force acting on it from the conveyor
.

I keep asking you, If the conveyor belt moves,how is it acting on the aircraft?

[nero279]

I'll say again -

All you have to detemine is whether there's any possible way of a significant transfer of force from the conveyor belt to the body of the plane through it's freewheeling wheels?

[TonyN]

I'll say again -

All you have to detemine is whether there's any possible way of a significant transfer of force from the conveyor belt to the body of the plane through it's freewheeling wheels?

Exactly. And I doubt it. But that was the angle I was going for at the start of the thread, as its seemed fun at the time! seems like a long time ago!!

Antshiel

But no-one said it was on this planet!!

Most people here don't seem to be.