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# 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.

It's in the ballpark for Diomedia exulans (about 19:1, I rounded off 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'?
```

Let's say that I dropped you out of an airplane. Or that you got up there the same way that a wandering albatross gets up there.

How do your power requirements vary?
I don't start my marathon from the halfway point, although I have been called a winged whatever. When I talk about
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 that +/- 15% weight change affect your gliding range?

```and the Andes. Blackbirds that nest at 2500’ have lower
wingloads than sealevel nesters.
```

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.

OK. Let's take Stonker for example. From memory, he often left Scotland at a weight of about 26-29 pounds, and arrived 2 to 4 days later in Iceland at a weight of about 13 pounds. That is a weight change on the loose order of 50% during the course of that flight. On the other hand, the density ratio between sea level and 2500 feet is 0.929. That's about a 7.3% change. Which of the two changes 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.  Don't know that any of their usual haunts are at that altitude.`

--------- What this country needs is a really effective placebo. But beer works, usually.
`Myself, I was always partial to Budweiser.`

All the best,
Jim