Man, how did I miss this thread for 11 pages?

For all the people who are saying that the wheels do not provide the drive, they are right, they do not. But one force that Hoss has been telling you about "resistance", is gravity. the weight of the plane is pushing the wheels down to the belt. Okay, now in order for the plane to move at all, regardless of how much forward momentum is applied is applied, the wheels have to move because of gravity. If the conveyor speeds up as much as the wheels do, then the plane will go not go anywhere because of the rolling wheels and the moving conveyor cancleing each other out. I seen a post where someone said tie an airplane to a pole and it will take off.

Now the only way for the plane to become independant from the wheels is for there to be lift from the wings, which then the plane will start using the actual air speed. As long as the plane is on the conveyor, going no-where, there is no ground speed or air speed. 0 airspeed = 0 lift.

There is no wind available per the initial problem that was given to us. The plane will never be able to overcome the conveyors speed because it will never be able to generate air speed and acquire lift.

I am glad that I work for a mobile home company, cause I am gonna be watching this thing from this point on... Now I am gonna go and check out the post on that political forum...hehe


also there really is not enough information to draw a final conclusion... is the plane a prop plan or a jet plane? prop planes provide "SOME" of their own "air speed" by forcing wind over the wings.

jet engines do not provide any lift for the plane what so ever, only forward thrust.

 

Quote:
In the second, giant conveyor belt case, it is possible to generate enough wind around the wings to create enough lift to lift off the conveyor belt, but since the plane is still stationary relative tot he ground, it will not be able to fly away, only hover in ground effect.

O.K. lets assume that this is what would happen. Once the plane starts to "hover" the connection to the conveyor is broken and the plane takes off.

If you say "There is no wind" and none can be generated by the plane or the conveyor then this alone makes it impossible to take off. But that's cheating!

 

Nope .... still holding fast on the fact that it WILL fly.

1. Why would the wheels turn on the plane in the first place ? Because of forward momentum caused by the jet engines. There is no driveline connected to the wheels, they are free to turn just like the front tires on an older 2 wheel drive truck. The reason the wheels actually move (on the ground) is because the ground is stationary, unlike the conveyor.

2. The conveyer belt goes the opposite direction of the wheel spin, which in order to make the wheels stop turning, would actually match the speed and direction that the plane body is traveling. This means that both the plane AND the conveyer are producing ground speed as well as air speed.

3. Because of this fact, the resulting air traveling at that given rate of speed OVER the wings would cause the lift resulting in the plane taking off.

But I must say .... Hoss, you are one heck of a debator !!

(Us Pro-flight folks are still right though).
PISTOL

 

Yes, but the problem states that the belt moves the opposite the same amount as the planes wheels.

so if the wheels ever try to mmove, then the belt will also move the opposite direction as much...thus leaving no movement of the wings what-so-ever and resulting in no air speed to generate lift.

 

“The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of ROTATION.”

I take this to mean the the wheel is rotating clockwise and the belt counterclockwise (or vice versa), but the belt is at the same speed as the wheels.

***edit: to finish this thought...the belt would keep increasing the speed of the wheels exponentially, but there would be no force (ASSUMPTION) to hold back the thrust of the airplane as the wheels are free to rotate independently of the airplane movement.

 

Again, not true.

 

Okay...I give up. The plane won't fly but I can't think of anything new to say and I don't like repeating myself.

I'm glad to see that we have another "no-fly" guy joining the debate though.

Forgive me for being so blunt, but if you think the plane will fly then you're just wrong.

Now, I actually have to get some work done before they figure out that all this typing I'm doing is not earning the company any money.

 

True...when there is no wind.

Okay...NOW I give up.

 

and in our case there is no wind, therefore airspeed = groundspeed

 

Of course there is wind, there is forward movement ... there is just no wheel movement. The plane body is moving at the same speed and direction the conveyor is ... which depends on the amount of thrust coming out of the rear of the engine.

This is MUCH better than politics and religion .

PISTOL

 

u got it backwards, the belt is moving the towards the rear of the plane

 

Its Gonna Stay In The Same Place And Not Move At All ITS LIKE RUNNIN ON A TREADMILL OR PUTTIN A REMOTE CONTROL CAR ON ONE IT DOSENT GO ANYWHERE UNLESS U MAKE THE SPEED OF THE CAR GO FASTER THAN THE BELT

 

Without giving a huge class on aerodynamics and theory of flight, the plane will take off

The jet engine or the prop is providing forward thrust which creates air speed which creates the lift over the wing. In a normal take-off(with no wind) the air speed matches the speed at which the wheels turn. On the conveyor belt the air speed would still be the same but the wheel speed would go up exponentially.

For example, find a conveyor belt and have your wife stand on a skateboard and hold onto the end of a rope. You stand at the other end of the conveyor belt and start pulling the rope and she will come closer. Now turn the speed up. She will continue to move forward at the same speed but the wheels will be rolling faster(the amount of force to pull will remain about the same).

Hope this helps!

PS- When she gets close to you turn the speed up all the way and let go!

 

I changed my mind. Can I do that? No, no I am not flip floping, just tought of a better way to ilustrate the problem and now I see it diferent.

Here we go:

The engine provides thrust or in other terms a forward FORCE.
Since this force is NOT chaneled through the wheels the wheels become irrelevant, or they could be floats, greased skids etc.

Now lets go back to the FORCE (and may it be with you all) it is applied to the frame through the engine mounts and as such its source can be replaced with anything of equal magnitude. USE A GIANT RUBBER BAD. Tie one end to something independent of the plane or the threadmill, strech other end to plane, secure. Let brakes go. If the rubber band retracts, and it will, you will have forward motion. Given a big enough rubber band the plane will accelerate to the point where air speed over the wings will generate enough lift to make the plane fly. Gliders take off on this principle.

 

an air boat on a river has to over come the flow