[ExI] fun memories of rocket stuff from a long time ago

[spike at rainier66.com]

Hey cool.  I was cleaning out a bunch of old junk and ran across a tech
paper I wrote in 1989.  I was pitching it at a aerospace conference that
year, and explaining how I had found a standard atmosphere model, which back
in those benighted times was a page in a reference book.  It gave
atmospheric characteristics as a function of altitude, such as temperature,
density, pressure and all the usual stuff you would need if you wanted to
model a rocket launch.

 

Over on the second to the last column is dynamic viscosity, which you need
to model if you want it to be accurate, for that number influences drag.  I
wanted my model to be accurate.  So I scanned the data into digital format
and put it in my spreadsheet, along with rocket motor performance data (fuel
rates and thrust, etc.)

 



 

But for some damn reason, my model kept screwing up at around 15k ft, and I
couldn't figure out why.

 

I eventually traced it back to a mistake in the table in the book.  The
numbers 3 and 2 were switched.  Shoulda been .23544 there.

 

Hey rocket science is unforgiving of fools and electric car moguls:

 



 

I fixed that, then the spreadsheet returned answers that agree with actual
real-world rocket performance.

 

I don't know that I kept a copy of that spreadsheet, probably not, but Keith
fooled with it for a while back in about the mid 1990s.  I used it a jillion
different ways in my launcher studies, trying to see if there is any
configuration that makes single stage to orbit practical.  After calculating
it a hundred different ways, my conclusion is that single stage to orbit can
be done.  You just can't carry enough actual payload to make it worth doing.

 

Second conclusion: anything you can do with one stage can be done better
with two.

 

History and Mr. Musk pretty much confirmed everything I learned back then
and if Keith has any commentary on it, it should be interesting.

 

We were primitive savages back then.  We had fun.

 

spike 

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