The plane will take off because the jet engine is moving AIR and has absolutely nothing to do with the ground. The wheels won't be moving through the whole take off.

When the body of the plane starts to move, the wheels will start to rotate (which will be countered by the conveyer belt also moving ... thus stopping the wheels rotation) HOWEVER ... just because the wheels aren't moving, it doesn't mean that the thrust isn't moving the body of the plane.

If you did the paper under the toy car experiment and added to it by blowing on the back of the car hard enough (Hoss has that kind of hot air pressure) ... it will move forward regardless of what the wheels are doing and regardless of how fast you pull the paper.


Uuuuggghhh ... I really need a cup of coffee now.

PISTOL

 

The only way this plane is not going to take off is if it is hooked to a DCTD going the other way.

What about a sea plane??? The ground (Earth) is rotating about 1000+ mph one way or the other and they still get off the ground. How about a ski plane??? same thing.

It doesn't matter squat which way the conveyor is turning or how fast. The jet engine (or prop engine) pushs against the plane not the wheels so it moves forward. When The air flow over the wing reaches flying speed , up she goes.

Aircraft depend on air speed not ground speed.

 

Alright, I'll pop in here a second time....Let's flip the scenario. If the plane is coming in for a landing...on the same conveyor belt...which will match the wheel speed as soon as they touch down....You "No fly" guys are basically saying the plane will come to an IMMEDIATE stop. Right down to 0 air speed just like that. That is, assuming there's no wheel slip, which we are assuming. Since you guys say the wheel speed and conveyor speed cancelling each other out are all that matters, the plane should immediately stop.

However, your theory doesn't take the other forces into account, such as thrust from the engines...or forward momentum (in the landing scenario). If this theory really worked I would think the navy would install conveyor belts on all the aircraft carriers to make landings easy!! No more tail hooks, just land on the conveyor belt and you'll immediately stop.

I still say.....THE PLANE WILL FLY!!

Very interesting debate though

 

When the only source of power is your legs you are correct. When your source of forward motion is thrust against air (which is NOT tied to the ground) you'll have forward motion and fast moving wheels. The speed of the coveyor is only matched to wheel speed not airspeed.

Using your example, You reach up and grab a rope that is moving over the top of you and will carry you down the conveyor. Your legs (wheels) will just spin faster, but you will have foward motion.

What you guys are not seeing it that the thrust of the engine is independant of the wheels / conveyor.

 

There is your mistake, that assumption is incorrect, sorry. Ground speed is not equal to airspeed. On a windy day I can be sitting in the plane, engine OFF and register the speed of the air (airspeed) and my ground speed is 0. On take off (same situation) my take off roll is WAY less than normal due to the "free" airspeed from the wind. My ground speed is also WAY less than normal. Conversly, if I land with the wind (BAD thing to do) my ground speed is WAY higher (more dangerous) than normal, but my airspeed MUST be the same, or I fall out of the sky (stall).

I know it's tough to be an Aggie. ..................... I"M KIDDING! Hoss, look at it this way. You were right the first time!

This is a fun debate! But what do I know, I'm just a Geko?

 

Even ball bearings have friction. The only way the plane would get off the ground is if it were a hover craft, in which case there truly would be no friction between the conveyor and the plane.

The wheels WILL spin as fast as they want....faster and faster as more throttle is applied to the engines. However, the conveyor will spend JUST as fast and the plane won't get anywhere.

 

when your on the ground air speed and ground speed are the same.

 

ok if the engines are NOT on and the conveyor is moving backwards, wont the plane go backwards as well? bearings have no bearing() on this equation

 

Ummmm....no.

As I said before, the speed of the wheels has a direct correlation to the thrust of the engine. You cannot separate the two.

When a plane takes off on a runway do the wheels rotate? Of course they do. The same would be true for the conveyor, except that the conveyor is pushing back, effectively canceling out the thrust provided by the engines.

In your toy car analogy, you are forgetting that the conveyor ALWAYS matches the wheel speed. You can blow all you want, but every time you do the conveyor will speed up and the car won't move.

 

Air speed and ground speed are equal. 1 mph is 1 mph whether it's in the air, on the ground, or on the water.

Let's take your sea plane analogy and try to take off in a raging river. Say the river ALWAYS matches the speed of the plane, but in the opposite direction. Just like with the conveyor, that plane will never get up. Same with a ski plane if you put it on snow that is always moving at the same speed as the plane but in the opposite direction.

 

The difference between landing and taking off is that a landing plane has momentum. The plane on our conveyor belt does not.

 

Let me post this again for those of you who STILL don't get it:

READ CAREFULLY AND SLOWLY:

Ground Speed = Air Speed (because the plane is sitting on the ground and there is no wind)

Wheel Speed = 150 mph
Conveyor Speed = 150 mph (because it always matches wheel speed)

Wheel Speed - Conveyor Speed = Ground Speed

150 mph - 150 mph = 0 mph = Ground Speed = Air Speed

Wheel speed is a product of engine thrust so you cannot separate the two like so many of you are trying to do.

I hope you didn't buy a ticket for that plane because it ain't goin' NOWHERE!!

Now, for the sake of getting this bird off the ground let's put some limitations on this conveyor belt and see what happens. Let's say the conveyor belt has a maximum speed of 150 mph. Using the same logic from above, let's look at the equation with this new limitation.

Ground Speed = Air Speed (because the plane is sitting on the ground and there is no wind)

Now let's say that the wheel speed is 300 mph and see what happens.

Wheel Speed = 300 mph
Conveyor Speed = 150 mph (because I put that limit on it above)

Wheel Speed - Conveyor Speed = Ground Speed

300 mph - 150 mph = 150 mph = Ground Speed = Air Speed

So, if you limit the conveyor the plane can take off. Otherwise, it's grounded.

If THAT doesn't make it clear to you infidels then I don't know what will.

 

gig 'em hoss!

the simplest way i can think to compare this too is a boat in a river. if the river in flowing at 30 knots and the boat is flowing upstream at 30 knots, it is stationary. suddenly there is a flood and the river's speed increases to 50 knots, so does the boat and is still stationary. get it now?

 

hey hoss, i think we scurred 'em away

 

Not if the conveyor always speeds up to match your leg speed...which is what you said occurs in this little riddle. In that case your legs would slip though and the rope would carry you away. In our plane scenario we are saying there is no wheel slip.