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kccustom

Can the plane take off?

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Uh, they exist, what do you think they test F1 aerodynamics on the sidewalk?

 

doh.......... in a wind tunnel .................to match the WIND VELOCITY hence the down force generated on the car there is also a rolling road which is basicly two rollers(for each wheel) that replicates the road

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Guest thespin

The problem is stated VERY ambiguously which means we cannot address it without making SEVERAL assumptions without knowing if any are valid. So lets make a few and try to interpret the statements from a Physics viewpoint.

 

We know that Speed is not the same as rotation or angular velocity, that Speed is measured relative to a reference considered 'stationary'. And that Velocity is Speed in a specified direction.

 

It seems reasonable to ASSUME the conveyor belt's main surface is horizontal. It's also reasonable to ASSUME that the 'speed' of the conveyor belt refers to its top surface - not to the conveyor as a whole - and ASSUME that the conveyor as a whole is stationary relative to the air above it. Let's also ASSUME that there is no slipping/sliding of the aircraft wheels against the conveyor belt. And ASSUME that the speed of the top surface of the conveyor belt is sufficient for takeoff of that particular aircraft in a no wind situation. And ASSUME that the aircraft faces the same direction as that which the top surface of the conveyor belt is moving. WHEW!!

 

If we further ASSUME that the 'speed' of the wheels is also measured at its 'top' relative to the same 'stationary' point we use to measure the speed of the conveyor belt, then the bottom of the wheel is moving WITH the conveyor belt at the same speed and the aircraft is stationary relative to the air above it and the aircraft doesn't fly (unless as someone mentioned it's a Harrier or something similar).

 

Other types of wheel speed assumptions are more complex since we have to take into account both the speed of the particular wheel surface and the resulting speed of the aircraft.

 

If we slow our top wheel surface to zero, the aircraft moves with the top surface of the conveyor belt and takes off but no part of the wheel meets the criteria of having a speed of 'opposite direction'. And it only gets worse if the 'top' of the wheel begins to turn in the same direction as the top of the conveyor belt.

 

However, we CAN make the assumption that the 'speed' of the wheel refers to the wheel as a whole. In this case, the aircraft as a whole moves in the opposite direction with the same speed as the top surface of the conveyor belt and can fly if we CHANGE OUR ASSUMPTION about which direction it faces and about the wheels slipping on the belt.

 

No wonder there is no agreement.

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Perfect...everyone unsubscribed, now I can try :P

 

Since when does a plane need a runway to fly? If a plane relied on the ground in order to move, how did any of those test planes that were dropped from the underbelly of another plane ever fly?

 

The engines push the aircraft through the air, not drive the wheels.

 

The plane would move forward, producing lift, and the plane would fly.

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Perfect...everyone unsubscribed, now I can try :P

 

Since when does a plane need a runway to fly? If a plane relied on the ground in order to move, how did any of those test planes that were dropped from the underbelly of another plane ever fly?

 

The engines push the aircraft through the air, not drive the wheels.

 

The plane would move forward, producing lift, and the plane would fly.

 

I agree, I don't think it makes a difference how fast the wheels under the plane are spinning since they don't really provide any function besides holding the plane off the ground. The plane would still accelerate, gain speed and produce lift. If a plane was going down the runway and all of a sudden the ground started moving in the opposite direction it wouldn't affect the planes speed...the wheels would just spin faster.

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Perfect...everyone unsubscribed, now I can try :P

 

Since when does a plane need a runway to fly? If a plane relied on the ground in order to move, how did any of those test planes that were dropped from the underbelly of another plane ever fly?

 

The engines push the aircraft through the air, not drive the wheels.

 

The plane would move forward, producing lift, and the plane would fly.

 

That's the exact point I've been trying to make :):D :nod: :D:)

 

OK so my last post wasn't my last post.

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Guest thespin

Obviously the plane, if it's a working aircraft, CAN fly. The question is, however, can it fly given the 'constraints' so poorly described.

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If theres no air flowing over and under the wings it wont fly it really is that simple.

the main reason that those test planes were dropped from larger planes is to conserve the amount of fuel carried, therefore allowing them to get longer test flights.

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Alright, I get what you guys are saying.

 

It can fly off the damn thing.

 

It's easiest to think of it with a jet. The engines start and essentially the damn thing moves forward, regardless of what it's sitting on (pavement or conveyor belt).

 

The only way the plane doesn't fly is if it doesn't move right? So the conveyor would have to move in such a way that the plane stays stationary. Except it doesn't matter how fast the conveyor goes, it's only turning the wheels on the plane at a faster rate, the plane still just goes forward.

 

It's harder to imagine a prop plane doing the same thing, though presumably it would.

 

God, talk about beating a dead horse. *sigh*

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All in all, the question is very ambiguous and is very difficult to answer.

 

I agree with many things that were said earlier, it is highly possible the resistance factor would come into play and the plane would not move, thus not fly.

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