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Re: pteros have lift-off

----- Original Message ----- From: "David Peters" <davidpeters@att.net>
To: "Michael Habib" <mhabib5@jhmi.edu>
Cc: "Mike Habib" <habib@jhmi.edu>; <jrccea@bellsouth.net>; <dinosaur@usc.edu>
Sent: Sunday, January 18, 2009 6:59 PM
Subject: Re: pteros have lift-off

Mike H. wrote: > Ground effect doesn't help quite that much.

Then why does every big bird launch I've ever seen include it?
It seems like a good way to accelerate AND fly. Such a system requires a less powerful takeoff.

No, it requires the same takeoff power. Ground effect doesn't let you fly slower, it just reduces the drag produced while maintaining level flight at high lift coefficients (slow flight). You still have to accelerate to the same ole speed during the launch, but you get to take advantage of the reduced drag thereafter (till you either climb out of ground effect, or speed up so that your lift coefficient declines to the point that the induced drag coefficient is insignificant.

Mike H. wrote: > Besides, a biped launch doesn't get many pterosaurs even close to cruise speed

And with ground effect acceleration, it doesn't need to. That's the point, I think...

Ground effect or no, the launch still has to get you at least to minimum flying speed. Bipedal launch won't do that for a typical pterosaur.