Airplane on a Conveyor Belt...

[AKIron]

How was this "demonstrated"?

He made a video demonstrating the force applied. I'll see if I find his post.

[AKIron]

Here they are.

LOL, OK


(Image removed from quote.)
http://hallbuzz.com/movies/wheel_on_sander_250th.AVI

(Image removed from quote.)
http://hallbuzz.com/movies/paper_treadmill.AVI

[100Coogn]

Are you joking?

umm, yes?   

Coogan

[Vraciu]

Here they are.

Not even the same thing as a self-propelled vehicle that doesn't generate forward motion through its wheels.

[AKIron]

His video shows that there is force applied to the wheel by the accelerating belt. The greater the acceleration, the greater the force that the engine of the plane will have to overcome to move the plane forward. I don't want to rehash this beat to death many years old argument but it was fun dropping by. 

[Vraciu]

His video shows that there is force applied to the wheel by the accelerating belt. The greater the acceleration, the greater the force that the engine of the plane will have to overcome to move the plane forward. I don't want to rehash this beat to death many years old argument but it was fun dropping by. 

As I said, you would need a belt traveling the speed of light if true.  The force required to stop a jet at takeoff thrust?   Now figure how fast that treadmill would need to go. 

Perhaps in absolute terms you are right. 

[NatCigg]

If the planes take-off speed is 100 mph and the belt is moving at 100 mph opposite direction, the plane should not get airborne. 

Coogan

this would only be true if the wheels were linked to the vehicle.  If the planes brakes are not applied, then think of the vehicle as being in neutral.  no matter how much the road moves nothing is transferred to the vehicle, the wheels just spin.


Now if a plane applied full brakes, on a 100 mph conveyor it would look something like this.

[Shuffler]

If the planes take-off speed is 100 mph and the belt is moving at 100 mph opposite direction, the plane should not get airborne. 

Coogan

The wheels roll freely and do not drive the plane. The prop will pull the aircraft through the air. The ground does not matter.

[Karnak]

One debate we had, maybe in the other thread, was whether the belt was required to match the rotational speed of the spinning wheels or the fuselage. If the latter then the planes takes off easily. If the former then the belt will rapidly accelerate as the wheels attempt to roll. This applies force to plane as Eskimo demonstrated and is quite capable of holding the plane in place given the belt is capable of unlimited acceleration and speed.

According to HiTech's calculations it would require a ludicrous 910 meters per second per second of acceleration on the belt in order to stop his plane from taking off.  While that is possible with the magical, infinite speed and acceleration belt, it is not feasible in reality.

The original idea posited a belt that matched the speed of the airplane, in other words the fuselage.

[Shuffler]

According to HiTech's calculations it would require a ludicrous 910 meters per second per second of acceleration on the belt in order to stop his plane from taking off.  While that is possible with the magical, infinite speed and acceleration belt, it is not feasible in reality.

The original idea posited a belt that matched the speed of the airplane, in other words the fuselage.

If the belt spins at the speed the plane body is moving then the wheels will be going twice the speed they normally would. Barring bearing failure, the plane would still be moving forward at speed and lift off.

[100Coogn]

The wheels roll freely and do not drive the plane. The prop will pull the aircraft through the air. The ground does not matter.

Thanks Shuffler.

Yeah, I read this article Airplane On A Conveyor Belt].
It pretty much says the same thing.
So now I am of the opinion that it will take off.

Coogan

[earl1937]

It's not standing still. The conveyor just spins the wheels, it doesn't hold the aircraft in place.

You mean to tell me that since the aircraft can't move, even though the wheels are spinning because of the conveyor belt moving, there by turning the wheels, would you please explain to us where the air flow over the wings are coming from?
No matter your thoughts on this thread, it is not going to fly until air flows over the wings, generating lift, which is what makes the aircraft fly to begin with!

[Golfer]

Earl man...

It ain't a car where the wheels drive the vehicle along the road and any movement is predicated on transmitting that energy via the wheels.

It's an airplane where the propeller pulls it thru the air and the wheels are just along for the ride.

She'll fly.  The wheels don't mean squat. It's why I can fly a Cub with skis on it in the winter. Or floats in summer.

One could use skis in the summer too but it'd take a whole lot of lube.

[Zimme83]

For a longer explanation: http://www.animations.physics.unsw.edu.au/jw/plane-conveyor.htm

[AKIron]

This is not the original thread here for this. In the original, the question was phrased ambiguously and addressed accordingly. Both conditions were discussed/argued with every permutation possible confused and misconstrued. It was a fun time.