Airplane on a Conveyor Belt...

[USRanger]

That was not HiTech.  Look at that grammar!

[VERTEX]

Originally posted by hitech
Vertex: I developed and designed electrical control systems for conveyors.


Eskimo: Different then the wheel speed question, the change of speed of the conveyor will effect the acceleration of the plane, but not change its current speed.
You could even integrate the acceleration back in to the controller to remove all conveyor delay.

Hence the theoretical system is valid.


HiTech

Thats rich, lmao.

Its been fun debating with you

[WWhiskey]

Originally posted by john9001
what means "wheel speed"?

 I was going to ask that question at one point as well, but got sidetracked on something else, is wheel speed the forward motion of the wheel or the rpm of the wheel itself?
 If the belt could move at the same speed of the wheel it would have  zero speed .if the rpm's are the question? well i give up

and V-22 still flies

[WWhiskey]

Originally posted by john9001
what means "wheel speed"?

 I was going to ask that question at one point as well, but got sidetracked on something else, is wheel speed the forward motion of the wheel or the rpm of the wheel itself?
 If the belt could move at the same speed of the wheel it would have  zero speed .if the rpm's are the question well i give up

and V-22 still flies

[quig]

So... I'm still wondering....

Do the stupid plane take off or not???

[Bizman]

So... I'm still wondering....

Do the stupid plane take off or not???

You've been wondering for eight years? See for yourself:

[Zimme83]

I would say that whats happen is that the belt causes the planes wheels to spin faster but the plane itself is still moving forward as normal. It would have been different with something like a seaplane on a river, taking off up streams increases the take off distance.

[quig]

Actually, if the conveyor matched the wheel speed exactly but in the opposite direction, the plane would never leave the ground without the conveyor itself moving. It would sit still and make a lot of noise, but it would never take off.

The video above does not emulate a conveyor moving in the opposite direction while exactly matching the WHEEL SPEED.

It's would be physically impossible for the plane to take off if the struts of the plane never move, thus no air being generate for the wings.

[GScholz]

Nah... As soon as the wheels start rotating the conveyor belt will start accelerating the wheels and generate a feedback that will cause uncontrolled acceleration of the whole system. The conveyor belt will break from overspend long before the wheels thus freeing the wheels to do their thing. Plane takes off.

But seriously, that's just an inaccurate description of the situation, and pedantics arguing over semantics. The way most people think the problem is meant to read is that the conveyor belt match the planes speed in the opposite direction. If so then if the take-off speed in 100 mph, the convenor belt is moving 100 mph in the opposite direction at take-off. So the wheels must rotate at 200 mph at take-off speed. Sure there will be some added friction, but not enough to prevent the plane from reaching 100 mph.

[Spitter]

Actually, if the conveyor matched the wheel speed exactly but in the opposite direction, the plane would never leave the ground without the conveyor itself moving. It would sit still and make a lot of noise, but it would never take off.

The video above does not emulate a conveyor moving in the opposite direction while exactly matching the WHEEL SPEED.

It's would be physically impossible for the plane to take off if the struts of the plane never move, thus no air being generate for the wings.

You couldn't be more wrong. Assuming perfect control of the conveyor, with no lag, the only affect would be that wheels (which have no affect whatsoever on the plane's ability to take off) would be rotating at twice the speed they would without the conveyor.

Mythbusters showed this with a scale model, and then again with a full sized aircraft. If you continue to disagree, take it up with reality.

Disclaimer: I am an actual aerospace engineer. 

[SFRT - Frenchy]

Remind me to never fly something you built 

[NatCigg]

The plane is only attached to the conveyor by the negligible force of gravity and the friction force related to the wheel bearing and tire grip. when the attachment force is overcome by thrust, any increase in attachment brought forth by the speed of the conveyor increasing, up to infinite speed, could easily be overcome by jet engine thrust, and maybe a properly leveraged 200 lb man. any additional thrust from the engine would move the object forward. 

lets try it!

no i did not watch the video. 

[Chalenge]

The way the airplane operates with respect to air doesn't change at all, so the plane will still accelerate and function as usual. I think Myth Busters messed up when they did not create a conveyor belt that accelerates at an ever increasing speed. After all, the original condition was that sensors detect motion and accelerate the belt to match aircraft speed. It doesn't matter in the end, just the same, because there really isn't anything that will stop the plane from flying.

[quig]

The spirit of the original question centered on the wheels and conveyor moving at the same speed in opposite directions.

If you chock the wheels of an airplane with wheel chocks, will the plane move if it cannot roll the wheels over the chocks? No.

If the conveyor is spinning at exactly the wheel speed for any given RPM, the situation will become the same as if the plane had the wheels chocked. The conveyor spinning in the opposite direction will create a force that will nullify the plane's forward movement.

The plane doesn't need the wheels to fly, no. But it does need them to move along the ground while taking off. If they don't move, for whatever reason, then the plane doesn't fly.

[EskimoJoe]

This argument is mind boggling and technically I think both sides are right in some way.

The aircraft needs air over the wings in order to takeoff, yes.

But in order for the air to move over the wings, the aircraft needs to generate forward movement (rolling forward on wheels).

I imagine if the engine and prop was dragging the plane along by the wheels, and a conveyor belt was preventing forward motion of those wheels, it would then not generate enough airflow over the wings to achieve flight.

I wonder what the Wright Brothers would say.