Monday, March 18, 2013

More about fuel

Lets take the table from the last post, and work with the Tsiolkovsky equation to get some concrete numbers.  First we have to nail a couple of data points down.
  • Engine - we will assume an exaust velocity of 500,000 m/s.  This is very hot, but not entirely insane.
  • Mass -  We will assume we are delivering something of the mass of a Kirov battle-cruiser.  That's 28,000 tons, or near as matters 3x10^7 Kg.
So with using the table from the last post, and having confidence in our high school algebra:

Acceleration, G Days Fuel Mass, Tonnes Mass Ratio
2.00E+00 6.40E+00 7.65E+13 2.55E+09
1.50E+00 7.38E+00 4.20E+12 1.40E+08
1.00E+00 9.04E+00 1.34E+11 4.48E+06
1.00E-01 2.86E+01 3.78E+06 1.27E+02
1.00E-02 9.04E+01 1.09E+05 4.63E+00
1.00E-03 2.86E+02 1.87E+04 1.62E+00
1.00E-04 9.04E+02 4.97E+03 1.17E+00
1.00E-05 2.86E+03 1.49E+03 1.05E+00

Of course,what this really underscores is the un-realism of SF in which large warships plunge through solar systems at multi-G accelerations for days on end.I am not sure I know how important this is to me, though.

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