On Thu, 09 Jan 2003 04:24:43 +0000, Ian Woollard
<[EMAIL PROTECTED]> wrote:
>Actually I used 1.2 / 2^(alt/6000) which is a bit nearer, so I wasn't
>quite as far out as you're assuming.
Ah, there's your problem, then. Acceptably low (91%) at 7600 meters,
100% at 13 km, 153% at 23 km, 204% at 30 km, 304% at 41 km...peak
overestimate is 5158% at 121 km.
If you change the base to 2.2, your peak error drops below 700%, at
the price of underestimating by 22% at 11 km. If you want a nice
simple algorithm which will give you good accuracy where drag is
important, and be way off (on the conservative side, which is good)
where drag is quite low, I'd say you're right on with what you've got.
It will give you slightly pessimistic numbers...bot not so pessimistic
that you can't make orbit.
I take it back: air density isn't the reason your vehicle is so heavy.
Darned if I know what is. I'm behind on my own sims...
>10m intervals? So I'll know the atmosphere to 0.01% and the Cd factor to
>10%, a real measure with a micrometer, cut with an axe kind of deal
Yep. I use a 100 meter interval myself, just because computing
something with great precision is not much harder than computing it
with low precision. One do have to vary the parameters, as you do, to
see what effect the variations have.
-R
--
"You haven't been lost until you've been lost at Mach 3."
-- Paul Crickmore
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