On Tue, 02 Jul 2002 17:20:04 -0700, Pierce Nichols
<[EMAIL PROTECTED]> wrote:
>>Those are awfully high numbers. Several references show plots more like
>>0-15-0.2 at subsonic speed, rising sharply to a peak of 0.5-1.0 just after
>>Mach 1, declining smoothly to around the original at about Mach 6. (One
>>source adds a comment that an overall average Cd is *not* a good
>>substitute for a Mach-dependent one -- even a vague approximation to the
>>shape of the curve is much better than trying to pretend it's flat.)
>
> Agreed -- if you're doing first-order trajectory optimization,
>which is how this discussion started, anything less would be pointless.
I maintain that some data is better than having no data. Since I'm
doing a zeroeth-order trajectory analysis - just tell me how high the
damn thing will go, plus or minus 3 db - I figured a flat curve was
close enough. I've killed the sim so I can do other things with that
machine, and I won't restart it until I have some CD numbers I believe
in.
Henry, one caveat - the people who generated the numbers you're
referencing had a lot more money than we do. We have a fair amount of
computing power - in fact, this sounds like a good application for
ERPS@Home - but not much money, so I suspect our drag numbers won't be
as good as those from people who reduce drag for a living. Being
naturally conservative, I want to take this into consideration in the
sims.
-R
--
"Sutton is the beginning of wisdom -
but only the beginning."
-- Jeff Greason
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