Physics of flight: Plane on a treadmill

[Guest Bender]

This is a classical dynamics problem, however with a twist.

Once you get thrust ratios that begin to exceed the forces in question, whatever it is that being considered here, the vehicle begins moving relative to the mass that causes lift.

If that thrust begins to move the airfoil fast enough through the air mass to create lift that appraoches the weight of the vehicle, it's going to begin to lift from the surface it's contacting.

You can make a block of concrete fly if you put a big enough rocket on it.

I'm not sure what's so fascinating about this really, other than discussion, but sure, what the hell, okay.

BENDY

[RangerMateo]

This is a classical dynamics problem, however with a twist.

It's really more a thought experiment in relativity and the differences in the way wheels are used in cars and aircraft. In aircraft wheels only serve to decouple the aircraft's motion along it's longitudinal axis from the ground (and to do it as efficiently as possible!) during takeoff. In a car, it's exactly the opposite...the wheels are intended to couple the car to the ground. That's why the car won't move and the plane will.

Here's the extension. Our a/c in question just took off normally from said treadmill does a standard pattern and comes back around to land (Again in the opposite direction the treadmill is traveling)...does he land in the same distance, longer, or shorter.

[Riddller]

Here's the extension. Our a/c in question just took off normally from said treadmill does a standard pattern and comes back around to land (Again in the opposite direction the treadmill is traveling)...does he land in the same distance, longer, or shorter.

OK, I'll bite.

It depends. It's been said in this discussion that the wheel friction is negligible or zero. I think that was in reference to the amount of forward thrust applied during takeoff. When you're talking about landing, though, other than aerodynamic braking, wheel friction is the ONLY force acting on the plane (assuming no braking... come to think of it, it applies when braking too, just a lot more).

If you assume zero friction, then the landing roll will be the same.

If there is any friction, the landing roll will be shorter, because the wheels will be turning twice as fast as normal, twice as much contact with the runway, and therefore twice as much opportunity for the friction to act on the wheels and by extension, the plane.

discuss.