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The bird claps the trailing edge of the wings, and leaves a small pocket of air at the leading edge. As the bird flaps down, the pressure at the trailing edge drops, pulling the pocket of air at the leading edge. The under side of the wings create high pressure by capturing some air, the high pressure air bleeds into the low pressure pocket created on the downbeat. Two vortices are created behind the bird. On the subsequent upstroke, the bird positions its wing to take advantage of the vortex. You can see the vortex lift, what the people in the video refer to as ripples in the primaries. The bird positions its wings to ride the vortex which creates lift in effect sucking the bird's wings together on the upbeat. It's physical energy spent mostly on the downbeat, as it rides the vortex on the upbeat.

The bird claps the trailing edge of the wings, and leaves a small pocket of air at the leading edge. As the bird flaps down, the pressure at the trailing edge drops, pulling the pocket of air at the leading edge. The under side of the wings create high pressure by capturing some air, the high pressure air bleeds into the low pressure pocket created on the downbeat. Two vortices are created behind the bird. On the subsequent upstroke, the bird positions its wing to take advantage of the vortex. You can see the vortex lift, what the people in the video refer to as ripples in the primaries. The bird positions its wings to ride the vortex which creates lift in effect sucking the bird's wings together on the upbeat. It's physical energy spent mostly on the downbeat, as it rides the vortex on the upbeat.

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[–] • 1 pt

My bird theory consists of 3 parts: a near weightless glider, an ideal dragless rope which hangs down from the glider, and a heavy man which can climb the rope as well as steer the glider.

The man begins at the bottom of the rope with the glider in a steady 100 fpm descent. He then climbs the rope at 200 fpm (relative to the rope). Since he is very heavy compared to the glider, the center of mass of the system ascends at 100 fpm thanks to his energy input. When he reaches the glider he releases the rope and allows the glider to zoom up very quickly, which it does effortlessly having very little weight of its own. He is in freefall for a bit but only loses a small amount of altitude compared with the amount of rope slipping up through his hands. He again grabs the bottom of the rope again and repeats the climb. In this way the system ascends at a constant 100 fpm using the man's climbing energy. The climb corresponds to the downstroke, the freefall to the upstroke. The man is the bird's body and the wings are the glider. If this model doesn't produce a vortex patter similar to a real bird I'd be very surprised.

[–] • 0 pt (edited )

Like the sky car?

https://www.youtube.com/watch?v=R-3adJdhqb4

Talk about porpoising.

[–] • 1 pt

Yea, except that's a maximally inefficient glider.