[gif] too much front brake and leaves cycle before impact

[goof2]

Originally Posted by '73 H1 Triple

3A) Since the brakes are not applied, the wheel are moving "backwards" at 60 mph. ( let's pretend somebody is at each wingtip holding the plane in place, only to prevent backwards movement ) The pilot applied throttle and the plane moves forward. Once he gets to 50 mph , the wheels are moving the equivilent 110 mph and the plane becomes airborne.

Originally Posted by Homeslice

Actually I have full understanding of what causes lift. Airspeed over a wing surface. That's all. What a treadmill is or isn't doing doesn't mean jack shit.

Originally Posted by '73 H1 Triple

All the treadmill would do is spin the wheels. The only "extra" would be addition bearing RPM from the wheels being on the treadmill.

~~~~~~~~~~~~~~~~~~

Maybe your looking at this from a different prespective than I am. See the "Myth Busters" episode on this? That's what I "see". A normal plane and a movable "runway" under the wheels. The prop generates enough forward speed to achieve takeoff regardless of the wheel speed.

You are both ignoring one of the central premises of the question, that the treadmill is able to prevent the forward motion you both know is required for flight. No the treadmill does not directly act on the source of the airplane's source of motive power, the propeller or jet. That doesn't mean the treadmill isn't creating friction/drag on the airplane. Maintain that part of the question and assume the treadmill can attain a sufficient speed so the friction/drag it imparts on the airplane through the tires, wheel bearings, etc. is enough to counteract the effect of the propeller or jet and keep the aircraft from moving. If that is the case, and the air remains still, then the airplane will not take off.

Originally Posted by Turbo Ghost

The speed of the wheels is irrelevant.
The whole problem with this entire scenario is the fact the wheels are not driven. Since the prop acts upon air and not the treadmill itself, there is no way to make it work.
As I said before, the purpose of a treadmill is to allow you to remain motionless relative to your surroundings. A motionless plane will not lift.

Making it work is why it is a bullshit question. The treadmill would need to be rotating at hundreds, if not thousands, of mph in order to generate enough friction to counteract the effect of the propeller or jet to prevent motion. Even if that could be done the tires would explode or the wheel bearings would melt in very short order likely resulting in a spectacular crash.

Physically possible? Probably not. If we ignore that and accept the premise of the question though, the airplane will not take off.

[Papa_Complex]

The plane isn't moving forward by driving its wheels, so the conveyor belt/treadmill is meaningless. It would have to move so quickly that the drag caused by friction in the wheels' bearings would be enough to match the energy put into forward movement.

http://www.youtube.com/watch?v=01Q83yxdDaI

[Homeslice]

Originally Posted by goof2

You are both ignoring one of the central premises of the question, that the treadmill is able to prevent the forward motion you both know is required for flight. No the treadmill does not directly act on the source of the airplane's source of motive power, the propeller or jet. That doesn't mean the treadmill isn't creating friction/drag on the airplane. Maintain that part of the question and assume the treadmill can attain a sufficient speed so the friction/drag it imparts on the airplane through the tires, wheel bearings, etc. is enough to counteract the effect of the propeller or jet and keep the aircraft from moving. If that is the case, and the air remains still, then the airplane will not take off.

If the treadmill was actually powerful enough to prevent the plane from achieving takeoff velocity, then it would not take off, and the wheel bearings would melt as you suggest. However, an example was made earlier of a giant fan blowing at it, in which case the wing surfaces could see sufficient airspeed to take off, regardless of what the treadmill, bearings etc. are doing.

[fasternyou929]

http://blog.xkcd.com/2008/09/09/the-...amn-treadmill/

[fatbuckRTO]

Originally Posted by fasternyou929

http://blog.xkcd.com/2008/09/09/the-...amn-treadmill/

Lol. Goof2 and I are clearly "JetBlue scenario" types. That kind of thinking made you unpopular at CF:

http://www.cycleforums.com/forums/sh...d.php?t=287810

But dammit, that's what the wording of this so-called "thought problem" implies. My favorite was when I was told my answer to a question about a plane on a giant treadmill was unrealistic...



Rofl at "pterosaurs for stability"...

[goof2]

Originally Posted by Homeslice

If the treadmill was actually powerful enough to prevent the plane from achieving takeoff velocity, then it would not take off, and the wheel bearings would melt as you suggest. However, an example was made earlier of a giant fan blowing at it, in which case the wing surfaces could see sufficient airspeed to take off, regardless of what the treadmill, bearings etc. are doing.

Sure, with the treadmill scenario on its own the plane cannot accelerate relative to the ground. Assuming still air it will not take off. If you move the air with enough speed toward the plane (and in the right direction) it will take off regardless of ground speed.

[goof2]

Originally Posted by fatbuckRTO

Lol. Goof2 and I are clearly "JetBlue scenario" types. That kind of thinking made you unpopular at CF:

http://www.cycleforums.com/forums/sh...d.php?t=287810

But dammit, that's what the wording of this so-called "thought problem" implies. My favorite was when I was told my answer to a question about a plane on a giant treadmill was unrealistic...



Rofl at "pterosaurs for stability"...

Yep, JetBlue for sure!

I had forgotten about the frictionless wheels part. That kind of changes things for me and I suspect explains why I never got deep in to the thread on CF. The treadmill always matching the speed and the frictionless wheels/tires are mutually exclusive. You can have one or the other, but both to me isn't worth thinking about.