Responsive Access Small Cargo Affordable Launch (RASCAL ...

Each of these alternatives will be closed in the performance aspects of the DSM (all
except cost, operations, and economics). Unless noted all alternatives represent one
change off of the baseline at a time.
Alternative 1:
The first alternative will be to change the second stage oxidizer from hydrogen
peroxide to liquid oxygen. The advantage of making this change is that the Isp of the
second stage will increase to 340 seconds vs. the 310 seconds for the hydrogen peroxide.
A disadvantage to this change is that the second stage will become larger. This is due to
the fact that the HTPB/LOX combination operates at a lower O/F ratio (1.9 vs. 6.5). This
smaller mixture ratio results in a larger rocket. This alternative configuration was closed
in the internal iteration loop of the DSM and this alternative resulted in the overall
payload capacity of the baseline RASCAL design increasing from 52 lbs to 75 lbs.
Alternative 2:
The second alternative involves changing the baseline first stage structural
material from standard aluminum to a metal matrix composite. This MMC will not only
make the design much lighter, it will also eliminate the need for a thermal protection
system (up to 1500 F). This is due to the fact that the reuse temperature of the MMC is
higher than the temperatures encountered by the first stage. The disadvantage to the
MMC is that it is an immature technology, and must be developed and tested far more
that the typical aluminum structure. This will cause the DDT&E of the design to increase
dramatically over the baseline. This alternative configuration was closed in the internal
iteration loop of the DSM and this alternative resulted in the overall payload capacity of
the baseline RASCAL design increasing from 52 lbs to 110 lbs.
Alternative 3:
The third alternative involves changing the trajectory of the upper stages so that
the second and third stages put the payload into a transfer orbit (80 nmi by 270 nmi
orbit). A fourth stage solid motor is then added to the upper stage to circularize the
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