Frisbees are models of saucers, what causes them to fly?

[Bythebookie2]

:confused:

[William A]

Two factors influence the flight of a Frisbee, gravity and air. Gravity acts on all objects the same way, accelerating their mass towards the center of the Earth at 10 meters/second. Once in the air, lift and angular momentum act on the Frisbee giving it a ballet-type performance. Lift is generated by the Frisbee's shaped surfaces as it passes through the air. Maintaining a positive angle of attack, the air moving over the top of the Frisbee flows faster than the air moving underneath it. Under the Bernoulli Principle, there is then a lower air pressure on top of the Frisbee than beneath it. The difference in pressure causes the Frisbee to rise or lift. This is the same principle that allows planes to take off, fly and land. Another significant factor in the Frisbee's lift is Newton's Third Law which states that for every action there is an equal and opposite reaction. The Frisbee forces air down (action) and the air forces the Frisbee upward (reaction). The air is deflected downward by the Frisbee's tilt, or angle of attack.

Spinning the Frisbee when it is thrown, or giving it angular momentum, provides it with stability. Angular momentum is a property of any spinning mass. Throwing a Frisbee without any spin allows it to tumble to the ground. The momentum of the spin also gives it orientational stability, allowing the Frisbee to receive a steady lift from the air as it passes through it. The faster the Frisbee spins, the greater its stability.
http://www.ktca.org/newtons/9/frisbee.html

[steve lewin]

Same as everything else that flies. Aerodynamics.

Steve

[Tim Green]

there is then a lower air pressure on top of the Frisbee than beneath it. The difference in pressure causes the Frisbee to rise or lift.

Why do people assume that this difference in air pressure causes the heavier object, in this case the frisbee, to move towards the lighter object, in this case the air above the frisbee?

If a vacuum between a frisbee and some air is going to be filled by anything, my money's on the air filling it, not the Frisbee.

[Dax]

because the higher pressure air below applies pressure towards the lower pressure air on top. Because the frisbie is in the way, its carried up with the air.

[Tim Green]

Air is lighter than a Frisbee.

And, we have a sandwich, with the bread being Normal pressure air ...

Normal pressure air
Medium pressure air
Lower pressure air
Frisbee
Normal pressure air

Again - I ask - why doesn't the Normal pressure air push the object with less mass (the medium pressure air has less mass than the Frisbee) into the region of lower pressure air?

In the case of a wing, it does. But the system cannot be looked at as a static model. The air above the wing's constantly being drawn down into the lower pressure, and thrust under the wing - lift. The low pressure area above the wing's constantly being recreated, even though air from above it's constantly being dragged into it.

The low pressure area's always there, and always the air tries to fill it, and as it does, it's forced under the wing - Newtonian lift.

No?