A plane on a runway, how smart is r3vlimited?

[DarkWing6]

Think about it guys - if this were possible, airport designs as we know it would change forever. Airports would only need maybe half the runways they have for landing purposes only. Small planes could take off from the tee box of a par 3 at your local muni. Anyway...

Excellent point. I love it!!! :borg:





*smiley used just cause it's cool and I have never used it*

[RobertK]

Ritalin Kid, it seems that you completely understand the situation, but are too stuck up on the friction of the wheels. This is a hypothetical situation, so I was looking at it in an ideal setting where there is no wheel bearing friction.

Even if you do take ito account the friction of the wheel bearings, there would not be enough friction to keep it from reaching a speed high enough to fly.
The plane would simply have to travel a few extra feet and it would take a few seconds longer.

The wheel bearing friction is minimal in relation to the thrust of the plane.

-Erik

If we're going to argue that this scenerio is in hypothetical fiction land then anything is possible.

In the real world I'm simply pointing out that there are many coefficients that would have to calculated to give a REAL ANSWER.

Based on your theory frictionless wheels would only exist in a world where energy can be created and destroyed.

In the real world gravity is pulling the weight of the plane DOWN to the earth and since it rests on wheels the weight of the plane creates a significant amount of friction at the conveyor.

If there was NO conveyor inertia would assist the plane during take off. Since the converyor is attempting to match it's speed and thrust a significant amount of inertia is being countered.

[erik325i]

Let me make this really simple guys, When you run on a treadmill do you have wind blowing through your hair?Didn't think so. Read the q: A plane is sitting on runway that can move (some sort of giant conveyer belt). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

Mr. Swiss, you fail to realize that the plane is different than a person on a treadmill because the wheels on an airplane are free spinning.
If it were a car on the treadmill, it wouldn't be able to move. A person on a treadmill wouldn't be able to move.

Because a plane does not drive by it's wheels (it uses jet engines), the wheels are free spinning. The jet engines will push the plane forward though the air. The conveyor belt is going to spin backward, and cause the wheels to spin faster, but not keep the plane from moving.

-Erik

[AdironRider]

22 pages and the question was answered on the first page.

Trust me guys, I have my pilots license. That and simple physics allowed me to answer the question in about .2 seconds. The plane takes off.

Think about how a plane takes off when its got pontoons on a lake. The engine overcome air resistance, the surface its on makes no difference.

[erik325i]

No they're not.. the wheels are also providing resistance in the form of friction at the conveyor.

BTW.. Too many of you keep leaving out the fact that the coveyor will increase it's speed with the plane.

Increase in speed = acceleration which requires more torque which is the equivlent of the plane's thrust. any addtional thrust made by the conveyor will increase the maount of friction at the wheels.

Ritalin Kid, it seems that you completely understand the situation, but are too stuck up on the friction of the wheels. This is a hypothetical situation, so I was looking at it in an ideal setting where there is no wheel bearing friction.

Even if you do take ito account the friction of the wheel bearings, there would not be enough friction to keep it from reaching a speed high enough to fly.
The plane would simply have to travel a few extra feet and it would take a few seconds longer.

The wheel bearing friction is minimal in relation to the thrust of the plane.

-Erik

[Mr.SWISS]

Let me make this really simple guys, When you run on a treadmill do you have wind blowing through your hair?Didn't think so. Read the q: A plane is sitting on runway that can move (some sort of giant conveyer belt). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

[Mr.SWISS]

Umm in the real world.. for the plane to fly.. it means everything.

The plane must first reach the proper ground speed for take off to occur and allow airspeed to do it's job.

But the ground is not moving. For your theory to work the plane would have to be traveling fast enough to overcompensate the conveyor to stationary, and then gain enough speed(air, ground watev you want to callit, We'll call it air friction) to supply sufficient lift greater than the planes mass.

[erik325i]

There is no airspeed in this equation.The engines would have to propel the plane enough to compensate for the conveyor, and supply the airspeed needed for lift.

How is there no airspeed in my situation? The jet engines are pushing the plane though the air. They will continue to push the plane though the air until there is enough lift fo the plane to take off. My whole argument is based on airspeed.

A conveyor belt is NOT going to keep the plane stationary.

-Erik

[RobertK]

And what does that have to do with airspeed? Absolutely nothing.

Umm in the real world.. for the plane to fly.. it means everything.

The plane must first reach the proper ground speed for take off to occur and allow airspeed to do it's job.

If you believe that an airplane engine creates air speed that caused the plane to lift then you are mistake. The engines simply push or pull the engine through the air to create lift they do not provide it.

Tell me this.. will this plane make it?



Now tell me that wheel size and weight do not matter.

[joshh]

This is quickly becoming my favorite thread...even over the 50+ page M/S50 thread.:giggle:

[Mr.SWISS]

No they're not.. the wheels are also providing resistance in the form of friction at the conveyor.

BTW.. Too many of you keep leaving out the fact that the coveyor will increase it's speed with the plane.

Increase in speed = acceleration which requires more torque which is the equivlent of the plane's thrust. any addtional thrust made by the conveyor will increase the maount of friction at the wheels.

And what does that have to do with airspeed? Absolutely nothing.

[Mr.SWISS]

I can't believe all you guys. Yes, the plane will take off.

Airplanes use jet engines that propel the plane forward. They are not powered by the wheels like cars.
Once you start the engines and try to take off, the speed of the ground has no effect. The Jet engines will still propell the plane forward enough to gain enough speed to fly.

Look at it this way, Let's say that the jet engines have the ability to push the plane 200mph upon take-off (I have no idea how fast they accually go, but that's irrellevant). The conveyor belt is also moving 200mph backward.
The plane is still traveling at 200mph, while the wheels are spinningh at 400mph.

-Erik

There is no airspeed in this equation.The engines would have to propel the plane enough to compensate for the conveyor, and supply the airspeed needed for lift.

[RobertK]

No, you don't get it. The conveyor belt would need to be the same length of a normal runway. Nobody is saying that they would be able to take off in place. The plane would still need to travel forward the same distance and reach the same speed in order to take off. All the conveyor belt is doing is spinning the wheels faster than normal.

-Erik

No they're not.. the wheels are also providing resistance in the form of friction at the conveyor.

BTW.. Too many of you keep leaving out the fact that the coveyor will increase it's speed with the plane.

Increase in speed = acceleration which requires more torque which is the equivlent of the plane's thrust. any addtional thrust made by the conveyor will increase the maount of friction at the wheels.

[craig4ie]

shit boys, IT FLIES

The wheels can be assumed frictionless and will therefore have no effect on the movement of the plane. They will simply spin.

In our physical world EVERYTHING is balanced by forces and the ONLY force on this plane is from the pressure difference between the front of the motor and the back of the motor over an area roughly the size of the motor.

if something that is frictionless has only one force acting upon it it will accelerate in the direction of the force.

In order to imagine how this would work in a frictionless case, imagine that the plane and the runway are magnetised to the same polarity so that the plane floats due to magnetic forces. Will the plane take off then??? Of course it will!

[StereoInstaller1]

Personally, I do not see how the plane could be kept stationary.

I think we are all in agreement that if no wind passes over the wings, no lift, thus no fly.

But since the thrust is NOT powering the wheels, but the body of the plane, I cannot see how it could be kept stationary, treadmill or not.

When you stop a plane by chaining it to the ground, you aren't chaining the wheels, but the body of the aircraft...even if the chain is actually connected to the wheels.

So the engines apply thrust to the body, so it will move, thus lift.

The treadmill has nothing to do with it.

Luke