Principles of flight?

[Mr Revhead]

then add thrust, and plane moves

cause the thrust is seperate from the wheels (which act as bearings allowing a speed diferential)

how does the conveyer counteract the thrust? as the only way it can act on the plane is through a frictionless (relativly speaking) medium? which rotates.... therefore negating the effect.

for example hold the plane in place and turn the belt. and the wheels turn with the belt..... add a motive force to the plane, and it moves.

because the wheels turn while the thrust moves the plane.....

[Chickenman]

Plane will not fly in this hypothetical situation.


IRL the limitations of the mechanical parts will either see the wheels explode and the plane be thrown backwards or the treadmill/travelator malfunction and the plane take off as normal...


But Real Life is for Pussies.

[RedMist]

Revhead So you are saying that when a plane takes off the wheels dont rotate?

Please explain how thrust does not directly affect wheelspeed.

If the wheels spin at 10,000 kph the conveyor spins at 10,000 kph in the reverse direction. Groundspeed = 0 unless the wheels skid.

No matter where the drive is coming from.

[Chickenman]

Sorry... got in the way of another disgustion


But you can still lick a fat one if you want

[Mr Revhead]

oh it does, but wheel speed doesnt effect thrust

while thrust effects wheelspeed, they arnt mechanicly linked.
becasue they arent mechanicly linked, other factors can effect one or the other, with out an effect on the other.



you know i bet theres some reason like the way ppl use parts of the brian that explains why some ppl just cant get this.
you know, like those "majic eye things"

[RedMist]

oh it does, but wheel speed doesnt effect thrust

while thrust effects wheelspeed, they arnt mechanicly linked.
becasue they arent mechanicly linked, other factors can effect one or the other, with out an effect on the other.

What other factors?

you know i bet theres some reason like the way ppl use parts of the brian that explains why some ppl just cant get this.
you know, like those "majic eye things"

Simple question. What speed are the wheels spinning when your plane takes off?

[Mr Revhead]

other factors... lots, i wasnt making that statement in relation to the original questions... more to show they are not mechanicly linked.

as for what speed they are spinning....
i am not sure exactly, i THINK twice the rotational speed of the planes speed.
by that i mean if the plane is doing 100kmh. the wheels are doing the rpm needed for 200kmh if on the ground

[RedMist]

other factors... lots, i wasnt making that statement in relation to the original questions... more to show they are not mechanicly linked.

So you are stating that in order to move forward the wheels dont need to spin.

as for what speed they are spinning....
i am not sure exactly, i THINK twice the rotational speed of the planes speed.
by that i mean if the plane is doing 100kmh. the wheels are doing the rpm needed for 200kmh if on the ground

Think about it. If they wheels are spinning at 200kph what speed is the conveyor doing?


-200kph, what speed is the plane doing? 0kph.

Try this...

Plane is on a conveyor as described. I'm suspended above the conveyor within reach of the tailplane. I push the plane, but as I attempt to move the plane the wheels turn, the conveyor accelerates to the point where my push is counteracted by the conveyor (actually fricitional forces between wheel and conveyor and bearing frictional losses) I push harder, the conveyor simply accelerates.
In order for me to move the plane forward I have to be able to rotate the wheels faster than the conveyor, but thats a constraint of the question, so it cant happen.

[blitza]

Simple question. What speed are the wheels spinning when your plane takes off?

Who cares? what has sufficent airspeed to take off got to do with wheel speed?



TOOT '06?

[RedMist]

Simple question. What speed are the wheels spinning when your plane takes off?

Who cares? what has sufficent airspeed to take off got to do with wheel speed?



TOOT '06?

Its the entire crux of the problem. In this issue you can rotate the wheels at 10,000 kph and the plane wont move an inch forward. So no airspeed.

[RedMist]

Simple question. What speed are the wheels spinning when your plane takes off?

Who cares? what has sufficent airspeed to take off got to do with wheel speed?



TOOT '06?

Its the entire crux of the problem. In this issue you can attempt to rotate the wheels at 10,000 kph and the plane wont move an inch forward. So no airspeed.

[Alycia]

A plane needs wind over its wings in order to take off.

If there is no wind and the plane is travelling at the exact speed as the ground then theoretically it will not take off.

stupid people who have nothing else better to do but dream up hypothetical things which could not possibly happen!

[Mr Revhead]

So you are stating that in order to move forward the wheels dont need to spin

no i didnt say that....

Think about it. If they wheels are spinning at 200kph what speed is the conveyor doing?


-200kph, what speed is the plane doing? 0kph.

wrong! you are STILL thinking in terms of the wheels moving the plane!
please tell me what is negating the effects of the engines thrust, which is pushing the BODY of the plane.

the wheels DO NOT move the plane, the allow a speed difference between the plane and the body.... they are bearings!

[Alycia]

wrong! you are STILL thinking in terms of the wheels moving the plane!
please tell me what is negating the effects of the engines thrust, which is pushing the BODY of the plane.

the wheels DO NOT move the plane, the allow a speed difference between the plane and the body.... they are bearings!

thats exactly right - its like saying a plane flys using only its wheels.

I have come to the conclusion the question is stupid!

[RedMist]

So you are stating that in order to move forward the wheels dont need to spin

no i didnt say that....

Think about it. If they wheels are spinning at 200kph what speed is the conveyor doing?


-200kph, what speed is the plane doing? 0kph.

wrong! you are STILL thinking in terms of the wheels moving the plane!
please tell me what is negating the effects of the engines thrust, which is pushing the BODY of the plane.

the wheels DO NOT move the plane, the allow a speed difference between the plane and the body.... they are bearings!

WRONG I am not thinking the wheels move the plane. I am thinking that the wheels have to spin in order to move. You are stating that the plane can move without spinning the wheels.

where the heck is this magical speed difference. At takeoff your wheelspeed is what? and what speed is the conveyor doing if it matched the speed in an opposite direction? As such what is your groundspeed? Simply explain how they can be disparate.

I've explained in may a post, including the one above yours that the only forces negating thrust is frictional forces on the bearing and wheel to conveyor.

[EVL GSXR]

wrong! you are STILL thinking in terms of the wheels moving the plane!
please tell me what is negating the effects of the engines thrust, which is pushing the BODY of the plane.

the wheels DO NOT move the plane, the allow a speed difference between the plane and the body.... they are bearings!

thats exactly right - its like saying a plane flys using only its wheels.

I have come to the conclusion the question is stupid!

I agree who give's a shit Plane's fly throught the sky enough said

[Mr Revhead]

thrust! pushes the body of the plane. it HAS to move.
the wheels as stated real early on in the piece just confuse the issue...
as the wheels rotate, they negate the effects of the conveyer belt on the body, because the body is being pushed by thrust.
the friction of the bearings etc wont stop it moving, if that was the case wheels wouldnt work!

unless there is a force acting with equal pressure on the body of the plane to counteract the thrust, it moves. as the only other force around is the belt, which cant effect it as it has no direct connection to the plane.

i rest my case, its all there

[RedMist]

thrust! pushes the body of the plane. it HAS to move.
the wheels as stated real early on in the piece just confuse the issue...
as the wheels rotate, they negate the effects of the conveyer belt on the body, because the body is being pushed by thrust.
the friction of the bearings etc wont stop it moving, if that was the case wheels wouldnt work!

unless there is a force acting with equal pressure on the body of the plane to counteract the thrust, it moves. as the only other force around is the belt, which cant effect it as it has no direct connection to the plane.

i rest my case, its all there

You failed to answer any of my questions. Simply because in your theroy the constraints cant be met.

Thrust? What? Thrust has nothing to do with it. You continue to state to ignore the wheel. Which is the basic constraint of the problem. If you bothered to read the question, "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
"
In order to move the body of the plane the wheels have to move quicker than the conveyor, which they will never do. Or are you stating again that the plane can move without spinning the wheels?

Friction, what fricitional forces do you think will be produced by a wheel spinning at 10,000kph? 100,000 kph ?

I restate my question.

At what speed are your wheels traveling at at takeoff.
At what speed is the conveyor doing?
What is the groundspeed?

[no_8wire]

thrust! pushes the body of the plane. it HAS to move.
the wheels as stated real early on in the piece just confuse the issue...
as the wheels rotate, they negate the effects of the conveyer belt on the body, because the body is being pushed by thrust.
the friction of the bearings etc wont stop it moving, if that was the case wheels wouldnt work!

unless there is a force acting with equal pressure on the body of the plane to counteract the thrust, it moves. as the only other force around is the belt, which cant effect it as it has no direct connection to the plane.

i rest my case, its all there

The ground under the plane is moving...
So as it moves "forward" the ground/belt moves back...as the plane is currently not airborne ( weight is still on wheels) the plane is moved back as the wheels cant spin faster than the belt and vice versa

[Punter]

Hmmm... after much thinking I have changed my mind, and now agree with redmist.

Why,

For the plane to move forward on the belt (relitive to the ground) its wheels must rotate faster than the belt is moving in the opposite direction, because the question states the belt will do the same speed as the wheels this cannot happen.

Therefore no matter how much thurst is applied the plane can't move, otherwise the same speed rule would be broken.