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Critical Mass
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Critical Mass was our
rocket club's group project in 2001. It is a LOC Caliber ISP (they
liked the looks, I liked the performance). We have flown it on an
H242 and look forwards to a flight on a J90 in the near future.
Keep reading to see how we built this rocket successfully in a group
environment. |
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| Flight
Log |
Flight
Details |
Construction
and Modifications |
RockSim
File |
Flight Log
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Flight #
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Motor
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Electronics
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Performance
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Comments
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| 1 |
H242-MT |
RRC2 |
1837 ft |
Good boost in gusty winds. No damage. |
Flight #1 ROC May 2001
The day was cloudy and with gusty winds, not exactly optimal conditions for flying our project. The planned I300T motor would push the Caliber 4000 feet and close to the speed of sound, and the conditions were a bit too extreme for flight with that motor. We instead bought an H242 and proceeded to load that into the
rocket. After packing the recovery system into the rocket, loading the altimeter and ejection charge, and preparing the motor, we were ready to fly. We walked to the check-in line and filled out a flight card. Loading onto the pad was immediate, because of the lack of people flying
rockets. After a group picture with the rocket, we armed the altimeter and walked back to the
range head. The LCO immediately selected, armed, and launched our rocket. Just as he said "One...", the wind that had been blowing at 10 MPH all day died. The rocket made a beautiful ascent to 1837 feet, did a tail stand, and ejected its parachute. We ran off for it downwind. The altimeter was reporting the altitude, and all was well. The rocket returned with a few scratches from being dragged along the lakebed by wind (which incidentally came up just as we got to the rocket).
Design and Construction
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Construction
Because this was our
school rocket, we made hardly any modifications to the stock LOC
kit. We built the entire thing at our meetings on Wednesday
afternoons. We used 5-minute epoxy. During the construction,
the members of the club learned such techniques as how to use sandpaper
for beveling fins (and losing their desire for sandpaper), how to mix
epoxy so it actually cures, and how to make internal fillets. It
took us around 2 months to build the rocket. We made two
modifications, and those were to add a Slimline motor retainer and to
add rail buttons. Additionally, the recovery system was switched
to 20 feet of tubular nylon and we added a heat shield.
Conclusion
When doing a group rocket
project, it is important to not build the entire rocket yourself; rather
have the group build the rocket and you help them with it. I was
very proud of our rocket club when they built this rocket- evidence that
their construction techniques were perfect was in how straight the
rocket flew with absolutely no roll. It is definitely gratifying
to watch a project from start to finish and have it work
perfectly. Especially when you helped first timers build it.
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