# Re: Pterosaur size

----- Original Message ----- From: "don ohmes" <d_ohmes@yahoo.com>
To: <dinosaur@usc.edu>
Sent: Saturday, December 16, 2006 9:15 PM
Subject: Re: Pterosaur size

Let me ask a flight question. Let us arbitrarily assume that you are a
bird, or a winged whatever, and that from a height of 1000 feet in no-lift
conditions, you can glide a distance of 20,000 feet. Now, let's add 15% to
your weight. Without flapping, how far can you glide in the same
conditions? Now, let's reduce your weight by 15%. How far?

--------- Ain't 20:1 high for a whatever? Just asking.

Not particularly. Diomedea exulans has a glide ratio of about 19-20:1. I rounded off to 20 for convenience in multiplying.

Going from thin limits.
However, remember we agreed about that launch/flight/landing thing
being what counts? How the hell you get way up there at a 1000'? How do your power requirements vary? I
don't start my marathon from the halfway point, although I have been called a winged whatever.

Let's say that I dropped you out of an airplane. Or, alternatively, you got up there the same way a wandering albatross gets up there.
flight or volancy in the context of biosystems, I mean the whole cycle. So I need a more precise term
that isn't as hard to type as 'ecologically viable volancy' or
whatever. Flight cycle, maybe?

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

```and the Andes. Blackbirds that nest at 2500’ have lower
```

Not for any reason to do with flight -- it's actually to do with launch, and
the variation between individuals or for one individual over time -- varies
by more than the difference in density due to the 2500' change in altitude.

----------I don't understand what you mean, but I think I probably disagree.

Let's take Stonker for example. From memory, when he left Scotland he weighed about 26-29 pounds. Upon arriving in Iceland 2-4 days later, he has been weighed at weights on the order of 13 pounds. That's approximately a 50% weight change. On the other hand, the density ratio from sea level to 2500 feet is 0.929. That's a change of approximately 7.1%. Which is greater?

-------------------- Damn. I was really hoping there was an answer to the max observed launch altitude re cygnus. Think there is one,
`Maybe, I dunno.`

or do they launch right on up to .59 atm?
`I doubt it.  I don't think any of their usual haunts are at that altitude.`

Jim