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Re: pteros have lift-off

David Peters wrote:

All I want now is minimum flight speed and apogee as a multiple of the unit specified by CG height at the beginning of the leap. Been gone all day. No reply, so far, to those queries.

Been a busy day for me, too, so I was unable to address those questions until now. Minimum flight speed varies according to planform and body weight, of course. What sort of aspect ratio do you assign to Istiodactylus? Do you have a preferred body weight? I have estimates of both that I use, but I'm more than willing to crunch the numbers for your version. Will only take a few minutes.

The apogee is determined according to simple ballistic equations. In actuality, because the inboard wing provides some lift even before the wing finger is extended, the trajectory is "better" than ballistic, but a ballistic path is quick and conservative. Therefore, it depends on the power fraction estimates and limb lengths - it is not a simple multiple of CG.

One last thing to note is that the long wing finger on things like Istiodactylus and Ornithocheirids has little impact on their minimum launch height, because the wing finger isn't unfolded until after the wing is well into the upstroke (leap first, unfold second). The changes in relative limb element lengths in azhdarchids improves launch ability not because the wing finger is shorter, but because MCIV is relatively longer.



Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280 0181 habib@jhmi.edu