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Re: Pterosaur size

----- Original Message ----- From: "don ohmes" <d_ohmes@yahoo.com>
To: <jrccea@bellsouth.net>
Sent: Sunday, December 17, 2006 6:25 AM
Subject: Re: Pterosaur size

You must have been up in the wee hours this morning, like me.

I repeat my question.  Quantitatively, how does a +/- 15% weight change
impact gliding range?

-------------- First answer got chopped out, I'll expand. Gets chopped out again, I will resend. Dredging this up from memory, if I have been wrong all these years, so be it. L/d= glide ratio. Sink rate increases w/ weight, as does minimum stall. More to the point w/ biosystems, increase in density = decrease in effective weight _WITHOUT LOSS OF POWERMASS OR FAT RESERVES_. Equal power, less "weight", lower sink rate/stall speed and more fuel/range. People speak of kinematic adjustments. These are MORE beneficial at higher density, as sink rate can ALWAYS be increased through planform adjustment. Also braking power is improved. No way this is not massively beneficial to a large bird, ESPECIALLY FROM THE ECOLOGICAL PERSPECTIVE. Increases in flight medium density (within reason) are beneficial to volant biosystems at Re > 10, period. 15% is significant.

I'll make the quantitative response myself, since you didn't. Changing the weight in either direction, up or down, has no impact whatever upon the gliding range. Whether heavier or lighter, starting from a height of 1000 feet in no-lift conditions you'd still glide 20,000 feet.

All the best,