Aircraft taking off from a treadmill: Debate

[sluggish]

Wow this is so dumb.. The power of an airplanes engines are not transfered to the ground like a car.. It's power to the air causing forward momentum and "airspeed" no matter what's happening underneath the aircraft itself (minus the force of friction).. The airplane will takeoff but the wheels will be spinning faster.. What is so difficult about this for people to understand?

http://bbs.hitechcreations.com/smf/index.php/topic,289123.msg3672572.html#msg3672572

[Die Hard]

IF...  It's MATCHING its speed its MATCHING its acceleration...

The distinction is whether it's matching the wheel's speed or the plane's speed.

No, it's not. The original poster said "the aircraft would not be able to lift off if it was on a treadmill because the treadmill would match its speed". If the aircraft is travelling at a speed of 100 mph the wheels are rotating at 100 mph at their circumference (duh!). Thus the treadmill is "matching" the speed by rotating at 100 mph in the opposite direction. If the treadmill matches the wheel speed, as in a runaway process where any initial input results in an infinite feedback loop, then the argument is, as I said, beyond stupid.

[sluggish]

If the treadmill matches the wheel speed, as in a runaway process where any initial input results in an infinite feedback loop, then the argument is, as I said, beyond stupid.

So we agree that the plane won't fly.  Brilliant.

[Die Hard]

No we don't agree, because this thread is not about your hypothesis, but the original poster's: "the aircraft would not be able to lift off if it was on a treadmill because the treadmill would match its speed"

As you said: "The treadmill might add ten feet to its roll."

Case closed.

[sluggish]

No we don't agree, because this thread is not about your hypothesis, but the original poster's: "the aircraft would not be able to lift off if it was on a treadmill because the treadmill would match its speed"

As you said: "The treadmill might add ten feet to its roll."

Case closed.

The only relevant factor is airspeed; the speed of air over the wings. That creates lift. The speed relative to the ground, treadmill, universe etc. is completely irrelevant.

So...  You disagree with yourself...  This is something you'll have to work out on your own.

[BowHTR]

Heres Your Answer To This Myth

http://www.straightdope.com/columns/read/2638/an-airplane-taxies-in-one-direction-on-a-moving-conveyor-belt-going-the-opposite-direction-can-the-plane-take-off

[Die Hard]

So...  You disagree with yourself...  This is something you'll have to work out on your own.

Nope. You're just being ( I hope for your sake) deliberately obtuse, and a poor loser. Read BowHTR link and take it gracefully why don't you.

"...Soon the foolish have persuaded themselves that the treadmill must operate at infinite speed.   Nonsense. "

[Denholm]

Taking friction out of the picture, the plane would lift off normally. Air flowing over the airplane's wings is not dependent on ground speed.

[saggs]

If you ignore friction, the treadmill is incapable of stopping the aircraft.  If you consider friction, the landing gear burns up and the plane falls into the treadmill and promptly gets flung violently backwards, killing everyone.

I considered friction, but isn't the treadmill subject to the laws of physics as well, doesn't it have some giant motor and bearings/bushings.



I figure the motor/bearings on any conveyor that large,  would burn out long before the wheel bearings/tires any a Boeing or Airbus would. 

Airplane wins: THE END   

[kotrenin]

We did this recently... again. http://bbs.hitechcreations.com/smf/index.php/topic,281455.0.html

[Dago]

Are any of you really so ignorant (or stupid) of the reasons aircraft fly as to think that really, a treadmill would have any effect on a plane taking off?   Wheel speed is totally irrelevant.  I honestly hope this consideration/argument is all tongue-in-cheek.

The jet engine, or in the case of a propeller driven aircraft, the prop, move the aircraft forward in relation to the air, and when the aircraft moves forward against the wind, the wings create lift, and with enough wind created will generate enough lift to overcome the weight of the aircraft.  Wheel speed in irrelevant, with skis and floats doesn't matter.

Ever see a good STOL aircraft takeoff?  With sufficient wind down the runway, and correct flap down settings, a STOL plane can takeoff with virtually no forward speed, it's all about wind over the wings. 

[Lepape2]

If the treadmill is rolling fast enough, the cohesion of the air with it will induce enough airspeed on the wings to generate a lift vector strong enough to lift the plane up... that's fact, that's science!

No seriously, I still can't believe this myth even exists, if it ain't for a massive worldwide failed joke. Its made for those people that get hands on flight controls for the first time and wonder why the plane rolls instead of turning horizontal like a road car when they yank the aileron controls.

[saggs]

Are any of you really so ignorant (or stupid) of the reasons aircraft fly as to think that really, a treadmill would have any effect on a plane taking off?   Wheel speed is totally irrelevant.  I honestly hope this consideration/argument is all tongue-in-cheek.

The jet engine, or in the case of a propeller driven aircraft, the prop, move the aircraft forward in relation to the air, and when the aircraft moves forward against the wind, the wings create lift, and with enough wind created will generate enough lift to overcome the weight of the aircraft.  Wheel speed in irrelevant, with skis and floats doesn't matter.

Ever see a good STOL aircraft takeoff?  With sufficient wind down the runway, and correct flap down settings, a STOL plane can takeoff with virtually no forward speed, it's all about wind over the wings.  

No, I don't think anyone here is that stupid.  I think the argument by those against (and it is valid) is that if the conveyor where able to roll fast enough that it would melt/destroy the wheel bearings and tires of the aircraft before the aircraft reached rotate speed.

Imagine the treadmill goes up to 1,000 mph.  Discounting all wheel friction, of course the plane would still move forward and lift off, but if rotate speed is say 150mph.  The landing gear wheels will be spinning at 1,150mph.  Now bring wheel friction back into the equation.   If those wheels failed at only 500mph, then like Boilerdown said the aircraft would only reach maybe 50mph forward speed before the gear wheels got destroyed and the aircraft belly lands on a conveyor going 450mph and gets flung violently backwards.

I however reject that on the premise that the conveyor at that speeds would fail before the aircraft's wheels would.  

I find this:


much more of a mental challenge.   If the turntable matched the speed of the rotors in the opposite direction.  Then it seems to be the rotors would just be sitting still generating no lift.   Not to mention the pilot would become some kind of gooey ooze on the inside of the windscreen spinning very fast.

[kotrenin]

While we are at it lets put a fan on our sail boat to make it go faster.

http://answers.yahoo.com/question/index?qid=20080506234729AApZqDe

http://www.youtube.com/watch?v=0CrXvOKPymk

[phatzo]