Sean,

I too have seen about 30% low thrust on the C6-5. I built a rocket of my own
design, calculated the CDA, then wrote software that used the thrust curves
ESTES published in order to simulate the flight. It produced a graph of
altitude vs time for a whole series of engines from the A8-3 through the
C6-7. Armed with several packs of engines the club headed out to the field
and gathered paek altittude data. All of the measurements came in within 5%
of the predictions except the flights using C6-7 which were 30% low.
Everyone wanted to blame the simulation software but I remain unconvinced to
this day.

That was the year that Dave and I went to Huntsville to compete in the
Nationals. While we didn't bring home any trophys, we did have a great time.
ESTES had just changed hands and the new president was attending. Several
competitors (I was not one of them, honest!) rigged ESTES engines to CATO
dramatically. They did this by sawing part way through the paper case and
then jamming the ignitor in with a sliver of wood with a little glue on it.

Just wanted you to know you're not alone.

Wynn Rostek

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