Plane on a Treadmill

[CyPlainsDrifter]

Re: CyBookie - Plane on a Treadmill

Please look at what you are posting and then think a little harder about it.

If the plane moves at 10 mph ground speed (independent of the treadmill) and the treadmill is moving at 10 mph going the opposite direction, the wheels are rotating at 20 mph, but the planes thrust is still much more than able to overcome the very slight friction that exists in the wheel bearings.

If the plane's takeoff speed is 80 mph, then the plane reaches 80 mph and takes off, while the wheels are rotating at 160 mph.

The treadmill is not going to be able to push the plane backwards, no matter how much some of you think it would be able to.

:notworthy:

You are right and I change my stance. The plane moves due to forces imparted on the surrounding air and it couldn't depend any less on what the wheels are doing. The real folly here is the distraction of the treadmill..... it could spin at pretty much any speed it wanted and in either direction and it would have little effect. It plays no part other than a supplemental "how much friction" argument which is relatively minute.

I stand corrected.... and that's final. :biglaugh:

 

[UofICy]

Re: CyBookie - Plane on a Treadmill

Again....think about this. The treadmill is not moving unless the plane is moving, correct? If the plane moves forward at 1 mph, the treadmill is moving backward at 1 mph. 80 mph and 80 mph and so on. Do you not believe that the friction in the wheel bearings cannot be overcome by jet propulsion or propellers?

No magic fairy dust needed......the plane would easily take off.

The wheels have nothing to do with it!:biglaugh:

 

[Warder60]

Re: CyBookie - Plane on a Treadmill

Here's a preview to distract everyone for a while

[ame=http://www.youtube.com/watch?v=KSBFQOfas60]YouTube - Mythbusters - Plane on A Conveyer Belt[/ame]

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

So your saying that if a plane is moving at 10mph (with the thrust of the engines) and the treadmill is running at 10mph in the opposite direction (ie. no air movement over wings) that the thrust of the engines (that is moving the plane at 10mph) is enough to lift the plane?

If that is what your saying your wrong on many levels.

Please continue to read on in that post past the area that you bolded.

If a plane's takeoff speed is 80 mph, it will reach that 80 mph ground speed and the treadmill would be going 80 mph the opposite direction, and the plane's wheels would be rotating at 160 mph. At takeoff speed of 80 mph, there is enough air movement over the wings to create lift.

And yes, even at 10 mph forward ground speed, there is air movement over the wings, just not enough to create enough lift to take off.

 

[UofICy]

Re: CyBookie - Plane on a Treadmill

Please continue to read on in that post past the area that you bolded.

If a plane's takeoff speed is 80 mph, it will reach that 80 mph ground speed and the treadmill would be going 80 mph the opposite direction, and the plane's wheels would be rotating at 160 mph. At takeoff speed of 80 mph, there is enough air movement over the wings to create lift.

And yes, even at 10 mph forward ground speed, there is air movement over the wings, just not enough to create enough lift to take off.

The Wheel speed has nothing to do with it. If the plane is going 80 mph on a treadmill that is going 80mph in the opposite direction there is NO movement of air across the wings. Therefore there is no "lift". Why is that so hard to understand?

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

The Wheel speed has nothing to do with it. If the plane is going 80 mph on a treadmill that is going 80mph in the opposite direction there is NO movement of air across the wings. Therefore there is no "lift". Why is that so hard to understand?

The plane is still moving forward 80 mph, right? Yes, it is, because that's the only way that the treadmill is moving 80 mph backwards.

Remember, ground speed is not the same as wheel speed. The plane is moving 80 mph ground speed, the wheels are doing double that.

Forward movement = air across the wings = lift. Why is that so hard to understand? :biglaugh:

 

[ISUCyclones]

Re: CyBookie - Plane on a Treadmill

I can't believe there is even a discussion about this. Why would a treadmill make one bit of difference? The propulsion of the aircraft is using the air for its medium i.e. not wheel driven.

 

[UofICy]

Re: CyBookie - Plane on a Treadmill

The plane is still moving forward 80 mph, right? Yes, it is, because that's the only way that the treadmill is moving 80 mph backwards.

Remember, ground speed is not the same as wheel speed. The plane is moving 80 mph ground speed, the wheels are doing double that.

Forward movement = air across the wings = lift. Why is that so hard to understand? :biglaugh:

No the plane is not moving forward. If you we standing next to the treadmill with the plane on it both moving in opposite directions at the same speed the plane will not move forward away from you just as you have no forward movement when you are running on a treadmill because your both going at the same speed.

 

[Steve]

Re: CyBookie - Plane on a Treadmill

Here's a preview to distract everyone for a while

YouTube - Mythbusters - Plane on A Conveyer Belt

My interpretation after watching the preview:

The pilot talks about matching his plane's speed to the tarp speed. How they define this will determine the outcome. If he does nothing, he gets pulled backwards. If he defines matching as providing enough thrust to hold his ground, he goes nowhere. If he defines matching as achieving an air speed equal to, but opposite of the tarp"s ground speed, he can produce lift.

 

[ISUCyclones]

Re: CyBookie - Plane on a Treadmill

So if a plane flies over a treadmill will it crash? The pentagon better get on top of this! In the case of an all out air battle we will surround our bases with treadmills. Can a helicopter take off of a giant elevator while it's going down?

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

No the plane is not moving forward. If you we standing next to the treadmill with the plane on it both moving in opposite directions at the same speed the plane will not move forward away from you just as you have no forward movement when you are running on a treadmill because your both going at the same speed.

A human running on a treadmill is not a valid comparison as humans use their legs for propulsion. In order for that to be valid, a plane would have to use its wheels to propel itself down a runway, and that obviously does not happen.

Think about what you are typing. "treadmill with the plane on it both moving in opposite directions at the same speed" You just stated that the plane is moving forward at the same speed that the treadmill is moving backward. The plane would not be moving if it was stationary, would it?

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

So if a plane flies over a treadmill will it crash? The pentagon better get on top of this! In the case of an all out air battle we will surround our bases with treadmills. Can a helicopter take off of a giant elevator while it's going down?

Damn, foiled by the treadmills again!! :biglaugh::biglaugh::biglaugh:

 

[UofICy]

Re: CyBookie - Plane on a Treadmill

A human running on a treadmill is not a valid comparison as humans use their legs for propulsion. In order for that to be valid, a plane would have to use its wheels to propel itself down a runway, and that obviously does not happen.

Think about what you are typing. "treadmill with the plane on it both moving in opposite directions at the same speed" You just stated that the plane is moving forward at the same speed that the treadmill is moving backward. The plane would not be moving if it was stationary, would it?

So tell me this. I'm on a treadmill wearing rollerblades with one of those jet packs on my back. Both me and the tread mill are "moving" at 30mph in opposite directions. You are standing 30miles away from both me and the treadmill. How long will it take me to reach you?

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

So tell me this. I'm on a treadmill wearing rollerblades with one of those jet packs on my back. Both me and the tread mill are "moving" at 30mph in opposite directions. You are standing 30miles away from both me and the treadmill. How long will it take me to reach you?

1 hour.

You're "moving" at 30 mph, the rollerblade wheels are rotating at a speed of 60 mph. This is assuming that your treadmill is also 30 miles long.

 

[ISUCyclones]

Re: CyBookie - Plane on a Treadmill

UofI just got OWNED. :wideeyed:

 

[JRCampy]

Re: CyBookie - Plane on a Treadmill

It's like you're assuming that the person on the treadmill with the roller blades and jet back will stand still when the treadmill is going 30 mph in the direction opposite they want to go, which wouldn't happen, not even with frictionless bearings.

 

[UofICy]

Re: CyBookie - Plane on a Treadmill

UofI just got OWNED. :wideeyed:

No, you both are just wrong. the wheels have nothing to do with it. If this was a seaplane going against a current on a river at the same but opposite speeds there would be no movement of air, therefore no lift. And if a plane in flight is flying into a headwind at the same "speed" at which it is flying you guys actually think there is forward movement. Apparently by putting wheels on the plane it magically adds forward movement.

 

[JRCampy]

Re: CyBookie - Plane on a Treadmill

Apparently they also think by going the same speed in the opposite direction of the treadmill magically doubles your speed... they do know the treadmill is going the OPPOSITE direction as the way the plane / person / whatever is traveling.

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

No, you both are just wrong. the wheels have nothing to do with it. If this was a seaplane going against a current on a river at the same but opposite speeds there would be no movement of air, therefore no lift. And if a plane in flight is flying into a headwind at the same \"speed\" at which it is flying you guys actually think there is forward movement. Apparently by putting wheels on the plane it magically adds forward movement.

Your post makes no sense, except for the fact that the wheels have nothing (or at best, very little) to do with it.

So, you don't think a seaplane's thrust would be able to overcome a current? Either way, it is a different scenario because a seaplane meets much more friction being on water than a regular plane does with its wheel bearings.

See this video for a simple example of what would happen with a plane on a treadmill:

[ame=http://www.youtube.com/watch?v=-EopVDgSPAk]YouTube - Plane vs. Treadmill Solved![/ame]


Even the little kid gets it!

 

[ISUAlum2002]

Re: CyBookie - Plane on a Treadmill

Apparently they also think by going the same speed in the opposite direction of the treadmill magically doubles your speed... they do know the treadmill is going the OPPOSITE direction as the way the plane / person / whatever is traveling.

It doubles the speed of the rotation of the wheels, not the speed of the actual plane itself.