Will it take off?

[Jeff_in_Atl]

Exactly... I think some people are just interpreting different things from the question - but in reality there are multiple scenarios.



hahaha... what is this? Chicken or the egg?

Hold up a toy car. Spin its wheel relative to your stationary position at 10 mph. Put it in on a treadmill that is spinning at 10 mph. To your stationary position, the car will not move forward or backwards on the treadmill. This is how I interpret the question, and in this scenario, the plane will not take off.

Yes but in your car scenario you are basing the car speed to a stationary object at 0 mph while the treadmill is 10mph to the stationary object. I don't think that is what the question requires.

on the other hand,

The car speed is 10 mph forward to the moving ground yet the tread mill speed is 10 mph in the opposite direction. But what made it that way? The car didn't accelerate to 10 mph. You accelerated the tread mill to 10 mph then put the car on it. I don't think this is what the question is asking for.

The question still says the plan "moved".

[Sean 94z28]

You're half right

Which half is wrong. The crux of every reply I have made to this post refers to the fact that plane speed does not equal wheel speed.

I have been aguing all along that by definition "plane speed" = air speed. And if you match a conveyer speed to air speed you still have a flying plane.

If you match conveyor speed to wheel speed, then the plane is stationary and by definition the "plane" is not moving the same speed as the conveyor. The wheels are, the plane is not.

[Trash man]

this is like learning how to burn a chip, im now confused and lost

[Jeff_in_Atl]

this is like learning how to burn a chip, im not confused and lost

Look what you've done here! LOL

[Trash man]

well its got every1 thinking.
unless i missed his post, im surprised wolfman hasnt commented

[Jay 02 TA ws6]

Which half is wrong. The crux of every reply I have made to this post refers to the fact that plane speed does not equal wheel speed.

I have been aguing all along that by definition "plane speed" = air speed. And if you match a conveyer speed to air speed you still have a flying plane.

If you match conveyor speed to wheel speed, then the plane is stationary and by definition the "plane" is not moving the same speed as the conveyor. The wheels are, the plane is not.

Then we agree

[TruckMuddr]

Man this topic has spread far.

http://www.google.com/search?hl=en&l...+take+off+belt

[fastTa]

Far from irrelevent.

Ok, how about extraneous, immaterial, impertinent, inapplicable. You pick. The ice is as arbitrary to airspeed as the name of the Captain piloting it.

A stationary airplane (regardless if it has wheels or skids) on a 100 MPH treadmill is going zero MPH. A 100 MPH airplane (also regardless of its landing configuration) on a 100 MPH treadmill, is still going 100MPH and will fly.

You just contradicted yourself from your previous proposition of "Far from irrelevent" and simultaneously affirmed my argument. LOL. Sean, I think you are confusing yourself now.

It might take more thrust to overcome the additonal friction you refer to. It doesn't change the circumstances of the question at all. Unless of course, you assume wheel speed = airplane speed. I don't.

Aircraft airspeed relative to the stationary ground measured in a conventional fashion from a sensor on the surface of the plane is the key fundamental and only fundamental here.

[Jeff_in_Atl]

Aircraft airspeed relative to the stationary ground measured in a conventional fashion from a sensor on the surface of the plane is the key fundamental and only fundamental here.

An air speed sensor on a plane measures the air pressure forced on it and has nothing to do with the actual speed measured on the ground.

[fastTa]

An air speed sensor on a plane measures the air pressure forced on it and has nothing to do with the actual speed measured on the ground.

That is PRECISELY my point Jeff! Man you guys need to drink your Ensure!!!! I'll say it for the third, and probably not the last time....the air velocity ACROSS the body and wings of the aircraft is the key here. And that is measured by a sensor that is attached to the surface of the aircraft at a conventional point of reference.

[Sean 94z28]

You said "It is an irrelevant argument to replace the converyor belt surface with the theoretical ice. Let's be thorough and accurate here."

You said the arguement is irrelevent and not the ice. My statements are very clear on this and relevent. The arguement is relevent because it says that no matter what surface is moving under a plane's landing device, the planes speed is the airspeed. It is the ice that is irrelevent, not the arguement.

You just contradicted yourself from your previous proposition of "Far from irrelevent" and simultaneously affirmed my argument. LOL. Sean, I think you are confusing yourself now.



Aircraft airspeed relative to the stationary ground measured in a conventional fashion from a sensor on the surface of the plane is the key fundamental and only fundamental here.

No contradiction whatsoever. Aircraft speed relative to a moving runway is not airspeed. When a question refers to how fast a plane is going, the only way it can be interpreted is "airspeed". That is how I read it from the beginning. If you match a conveyor with a plane's airspeed it will take off. If other people read it to mean wheel speed, or speed from a person on the conveyor, or speed from a dude in the shuttle, that is their interpretation. An interpretation I believe to be incorrect by definition. Why? :

"that tracks the plane speed ". There is only one definition for "plane speed" = airspeed.

[Jeff_in_Atl]

That is PRECISELY my point Jeff! Man you guys need to drink your Ensure!!!! I'll say it for the third, and probably not the last time....the air velocity ACROSS the body and wings of the aircraft is the key here. And that is measured by a sensor that is attached to the surface of the aircraft at a conventional point of reference.

You are assuming facts not in evidence. All the facts we have are what is in the question. It does not say where speed is measured. But from the question and reasoning as I stated in previous posts I say it is measured on the stationary ground.

[fastTa]

Here we go. Follow me here.

Here is the original proposition just for accurate reference.

A plane is standing on a runway that can move (some sort of band conveyer). 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).

Lets split this into 2 parts:

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction.

I think that goes without explanation, right?

Ok, second and most important part:

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)

Let's say a given aircraft requires an airspeed of 100.00 MPH across the body and wings of itself to provide enough lift to suspend itself off of the ground for a reasonably sustained period of time (flying). Let's say the conveyor runway is moving in the opposite direction at 50.00 MPH. Let's say the wind speed is mesured at 0.00 MPH in the vicinity of the aircraft and conveyor by a certified weather sensor. Let's also assume that the wheels are free spinning and the brakes are not enagaged and that the friction between the aircraft tires and the surface of the conveyor is identical to that of a conventional plane tire runway relationship.

Now, given this the plane would have to reach and maintain a speed of 150.00 MPH, measuring this in the fashion of plane to conveyor relativity in order for "lift off" to occur. A difference of 100.00 MPH and hence the airspeed required to "lift" the plane. I feel as if the question incinuates plane speed relative to the conveyor, BUT i am assuming they correctly mean to say actual airspeed as normally measured from a airspeed sensor on the plane for the sake of a "politically correct" argument.

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)

If the conveyor correctly senses (tracks)the actual airspeed of the aircraft measured by the aircraft sensor and then consequently adjusts itself to match that speed, you can see that the energy required to overcome the tire-to-conveyor drag would increase exponentially.

[Sean 94z28]

I feel as if the question incinuates plane speed relative to the conveyor, BUT i am assuming they correctly mean to say actual airspeed as normally measured from a airspeed sensor on the plane for the sake of a "politically correct" argument.

I think it is specifically worded the way it is, just to cause confusion between people who agree that a plane with sufficient airspeed to fly will fly.

[Trash man]

this is gonna go to myth busters, maybe they'll accept it?