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Re: pteros have lift-off

----- Original Message ----- From: "David Peters" <davidpeters@att.net

Unfortunately, that's really not where I'm looking for clearance. Let's move the video back a few frames and see if there is this thing called wing clearance much earlier in the launch -- closer to where the hands are still only inches to feet above the ground and rising quickly.

At that point, the hands are rising faster than 23 fps, and the wingtip is beginning to lower at somewhat less than that rate, but is still rising rapidly.

You mentioned the animal has .72 seconds to bring the wing to the beginning of the first downstroke. I'm wondering what the wing finger is doing at .1, .2, .3, and .4 seconds into the launch.

At 0.1 and 0.2 seconds, the manus is still on the ground, and the wingfinger is rotating tip forward, though inertial lag is causing the angle at the wingfinger pivot to start opening up. At 0.3 seconds, the manus is about 1.1 feet above the ground and accelerating upward, while the wingfinger is still lagging aftward with the pivot continuing to open. At 0.4 seconds, the manus is more than 2 feet above the ground and continuing to accelerate upward while the wingfinger continues to lag and open.; at this point, the wingtip is still higher than the manus, though it doesn't have to be. At 0.4 seconds into the launch and 0.15 seconds after lifting off, the animal still has 0.57 seconds remaining until the "top" of the leap. Since an entire wingbeat only takes 0.60 seconds to do both a complete combined upstroke and downstroke, you can see he still has plenty of spare time remaining to complete the unfolding of the wing when at 0.4 seconds from the initiation of the launch.

At 30 video frames per second, I'm just interested in those first 20 frames. If you want to continue working with Q, as a model, that's fine.

At 30 frames per second, the first 20 frames take 0.67 seconds. That's 2 frames more than it takes a Qsp to make an entire wingbeat including both up and downstroke. Is that a coincidence, or did you select 20 frames for that reason? BTW, I appreciate your permission to continue working on Q :-)

But remember there are (relative to torso length) longer winged pteros out there (in fact virtually all of them!)

Yes, but since they are relatively less massive and have relatively longer wings, launch is relatively easier for them. I'll try to remember that I spent approximately 80% of my working time for 3 years focused on A piscator. In general, you can usually tell when launch is becoming relatively more difficult for a pterosaur by looking at the shape of his dp crest.