will it take off?

[turnkey4099]

Is the speed of the plane that is supposed to match the conveyor belt its airspeed or its ground speed?

As has been stated, if the airspeed of the plane is high enough, it will fly even though the ground speed may not give that impression.

If the wind blows hard enough, a parked plane will lift off the ground. If tethered, it might "fly" in place. If not, it will likely flip over and break.

If the wind is blowing hard enough and a plane can fly slow enough, it could be seen to move backwards by an observer on the ground -- a 50 mph plane flying directly into a a steady 60 mph wind will have a ground speed of 10 mph backwards.

I have seen reports years ago where small single engine planes have LANDED backwards in the right conditions.

Harry K

 

[kwolfe]

AAAAAAAAAHHHHHHHHHHHHHH!!!!!!!!!!!!
This is maddening. THE PLANE WON'T FLY. It is remaining stationary to the gorund. If you were to tie a plane to the ground like a kite and crank up the engines all the way, the plane would not ift off the ground. It needs to be moving at a certain speed relative the the air around it to take off. This is the same reason why planes can take off at slow ground speeds with greater head wind, or need higher ground speeds due to greater tail wind. Also why they point aircraft carriers into the wind to have planes take off.

 

[RayH]

AAAAAAAAAHHHHHHHHHHHHHH!!!!!!!!!!!!
This is maddening. THE PLANE WON'T FLY. It is remaining stationary to the gorund. If you were to tie a plane to the ground like a kite and crank up the engines all the way, the plane would not ift off the ground. It needs to be moving at a certain speed relative the the air around it to take off. This is the same reason why planes can take off at slow ground speeds with greater head wind, or need higher ground speeds due to greater tail wind. Also why they point aircraft carriers into the wind to have planes take off.

HaHahahaha
That post is maddening.
The plane is not stationary to the ground, its not tied down, it rolls. The wheels turn. The plane can go forward or backward in relation to the ground or the conveyor.

Imagine if you will. You are standing on a treadmill with rollerskates on. Neither you nor the treadmill are moving because its matching your speed, which is 0.
A buddy shoves you from behind or pulls you from the front (acting just like a plane prop). Will you move forward on the treadmill? Of course you will. Even if the treadmill instantly matches your speed, you will still move forward because you are being pushed/pulled.
If you cant see that, I give up.

 

[RayH]

O.K. Last try (of course, I'm lying )....

Read these articles at the straight dope:


The Straight Dope: An airplane taxies in one direction on a moving conveyor belt going the opposite direction. Can the plane take off?
The Straight Dope: "A plane is standing on a runway. . ." No, it's not. Here's why.

In the question originally imposed, it seems like the plane will fly. I thought it would, too. But no one takes into account the force that the conveyor will exert on the plane. Read the first article... it supports the IT WILL FLY train of thought(even mentions roller blades, ropes, etc...). Then read the second article. It shows where most folks forget about the force exerted by the treadmill. If the treadmill was built to continue to accellerate to an infinite speed, the plane stands still.

The conveyor exerts no force on the plane. It exerts force on the wheels, but the wheels spin freely on the plane, so no force on the plane. If the brakes were on, there would be force on the plane, but with the brakes off, Nope, no force.

 

[RobJ]

Can I change my mine? I'll let you know when.

 

[RayH]

Can I change my mine? I'll let you know when.

Make it quick, you dont want to be the last one.

 

[BillyP]

For those that don't think the plane can take off. If that's the case, could an aircraft carrier launch planes off said conveyor?

 

[DieselPower]

HaHahahaha
That post is maddening.
The plane is not stationary to the ground, its not tied down, it rolls. The wheels turn. The plane can go forward or backward in relation to the ground or the conveyor.

Imagine if you will. You are standing on a treadmill with rollerskates on. Neither you nor the treadmill are moving because its matching your speed, which is 0.
A buddy shoves you from behind or pulls you from the front (acting just like a plane prop). Will you move forward on the treadmill? Of course you will. Even if the treadmill instantly matches your speed, you will still move forward because you are being pushed/pulled.
If you cant see that, I give up.

I think I may have come up with another easy way to explain why it WILL fly. Let's remove the plane from this situation. Same magic convyer. Now put a jet engine on the convyer that has 4 wheels mounted to it. If you start the jet engine up and turn on the magic convyer the jet engine will be propelled forward no matter what the convyer belt does. The engine is propelled THROUGH the air and not ON the convyer. If your mind can wrap itself around this concept now all you have to do is add two wings to the engine and now it's a plane. The forward movement of the engine that now has wings will create lift on the wings and up up and away it will go, convyer and wheels spinning like crazy but it will fly.

I to give up if you still don't get it.

 

[Paddy]

AAAAAAAAAHHHHHHHHHHHHHH!!!!!!!!!!!!
This is maddening. THE PLANE WON'T FLY. It is remaining stationary to the gorund. If you were to tie a plane to the ground like a kite and crank up the engines all the way, the plane would not ift off the ground. It needs to be moving at a certain speed relative the the air around it to take off. This is the same reason why planes can take off at slow ground speeds with greater head wind, or need higher ground speeds due to greater tail wind. Also why they point aircraft carriers into the wind to have planes take off.

I see your problem, you didn't understand the problem. The airplane matches the speed of the convayor but in the oposite direction, ie Convayor goes East 40 mph and plane goes West 40 mph (note the word match). You have assumed you measure airplane speed by wheel velocity. You measure the airplane speed by either two methods, referencing ground speed or air speed. In most cases, ground speed and wheel speed are the same when not flying, (hence the trick!!!!). Wind conditions are not given and safely assumed at ZERO or an infinite number of outcomes could be produced by this comunal group of tractor feins. So, can we move on here? Plane moves! When plane move through air fast enough, they do have been known to fly.

 

[MossRoad]

What is funny is how both sides are so sure the other is incorrect!

I see your problem...
You don't see the problem...
Yes, I do see the problem...
Let's try it this way...
You can't do it that way...
The plane exerts no force on the treadmill...
Yes it does...
Not when its moving...
Not when its flying...
It can't fly...
Yes it can...

Don't get so frustrated over something that is supposed to be fun, folks.