will the airplane take off? .... corrected

[why_me]

[MrSurly]

Err, no.
Not true.
Thrust from the engines acting against *air* moves the plane forward. The wheels have bloody -nothing to do with the plane movement other than to reduce the friction at the plane/tarmac interface.
Thrust generated will move the plane forward in relation to the ground. If the conveyer belt is *long enough* to exceed the planes take off roll, then it will take off from the belt. If not, then it will simply roll off of the belt.
Picture this: if the belt WERE 10000' long (and huge enough to support a plane) then even if the belt were traveling the same direction as the plane AND twice as fast, so the wheels on the plane are spinning *backwards to the plane's roll, the plane would still achieve lift and take off.. and the wheels would still have bloody-nothing to do with it.

Let's go a little further: let's make it a *float* plane.
Again, the floats do nothing except support the weight of the plane and alter the friction interface to the water.
The plane needs to achieve sufficient ground movement to attain air speed to produce aerodynamic lift. As long as the engines can provide enough thrust to move the plane against the existing friction, it doesn't matter if the tide is going in or out or if it's upstream or down.


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[fred1369]

the plane has to be moving forward just to stay in the same place on the conveyer belt. if it were not moving forward then it would be moving backward with the belt. if you were sitting on the wing you would feel the wind.

[why_me]

Originally Posted by MrSurly

Err, no.
Not true.
Thrust from the engines acting against *air* moves the plane forward. The wheels have bloody -nothing to do with the plane movement other than to reduce the friction at the plane/tarmac interface.
Thrust generated will move the plane forward in relation to the ground. If the conveyer belt is *long enough* to exceed the planes take off roll, then it will take off from the belt. If not, then it will simply roll off of the belt.
Picture this: if the belt WERE 10000' long (and huge enough to support a plane) then even if the belt were traveling the same direction as the plane AND twice as fast, so the wheels on the plane are spinning *backwsrds to the plane's roll, the plane would still achieve lift and take off.. and the wheels would still have bloody-nothing to do with it


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Exactly. The wheels have zero to do with anything.

[MrSurly]

I should have quoted... I was replying to Scabby's post but it takes me so long to type, I posted out of order.

But, yes, the wheels don't have anything to do with it except to reduce the friction or drag resisting movement. Now, if the BRAKES were set, now the whole equation does change a bit.


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[Scabbydoo]

I stand corrected.





but.......................it did sound good enough to cause the 'Pilot' to question.

[MrSurly]

Originally Posted by fred1369

the plane has to be moving forward just to stay in the same place on the conveyer belt. if it were not moving forward then it would be moving backward with the belt. if you were sitting on the wing you would feel the wind.

You don't make sense, here, Fred.
I'm assuming that per your illustration, the conveyor belt is *spinning* but the whole conveyor apparatus is stationary. If this is what's being posited, then the plane (it is implied) would be stationary.... but it's wheels would be spinning on the moving belt. In that case, no wind over the wings.
And then you throttle up the engines and they push the plane forward. Push it along the belt and then OFF the belt; engine thrust gives no damns about yer fancy-shmancy belt.


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[fred1369]

ah, I see the misunderstanding. I was assuming the conveyer belt had it's own motor running the belt opposite of the plane's direction. You and some others think the motion of the belt is due to the plane's wheels rolling it backwards. I think.

[Scabbydoo]

Believe what they are saying the belt does have its own power turning in the opposite direction of the wheel spin. What they are saying is that the thrust of the engines will propel the plane forward, regardless of the spinning belt and wheels, allowing the plain to achieve the required lift for takeoff.

[BigTOE]

Ed Zachery.

Now if we can get the whole conveyor moving fast enough we can make it fly too. Or at least Bob Hoover could have.


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[fred1369]

Originally Posted by Scabbydoo

Believe what they are saying the belt does have its own power turning in the opposite direction of the wheel spin. What they are saying is that the thrust of the engines will propel the plane forward, regardless of the spinning belt and wheels, allowing the plain to achieve the required lift for takeoff.

that is what I was saying. It will lift off from the same spot in which it started and then you will see the forward motion since the belt is no longer moving it backward.

[BigTOE]

Originally Posted by fred1369

that is what I was saying. It will lift off from the same spot in which it started and then you will see the forward motion since the belt is no longer moving it backward.

No.


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[fred1369]

why not?

[BigTOE]

Physics


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[why_me]