Shovel Ready

This is another 3″ minium diameter rocket with a rather simplistic approach using a fincan that can slide over any 3″ motor and go. The fins were sized for the shortest 3″ motor I have, the 3500 case. The rocket breaks at a single point with dual stage recovery via a line cutter, and all the electronics are mounted in the nosecone.  A short coupler section was glued 4″ up a piece fiberglass tubing that rests against the top of the motor. All said and done, the rocket with recovery system weighs just under 5 pounds.

(sorry for the cell phone pictures)

  1. #1 by Phil Babcock on November 1, 2011 - 3:35 pm

    Could you elaborate more on how you made the line cutter? I have heard of these being used before but never any real elaboration on them.


  2. #2 by James on November 1, 2011 - 8:42 pm

    Easiest way to make them is from a spent pistol casing and a rod that fits the ID of the shell. I’ll try to post a picture later this week of mine, it’s a different design but same idea. I don’t have a lathe so I “turned” the parts with a hand drill and made the o-ring grooves with a hack saw blade.

  3. #3 by Phil Babcock on November 11, 2011 - 7:26 am

    Where you concerned about zippering when the main chute deployed? When I have thought about doing this myself I haven’t quite figured out a way to entirely avoid this.

  4. #4 by James on November 11, 2011 - 5:38 pm

    Not really, the instability of the deployed configuration plus the drag of the wrapped up chute and shock cord keep the rocket off a ballistic flight trajectory. The altimeter recorded virtually no additional acceleration when the main inflated, pretty amazing actually.

  5. #5 by Phil Babcock on November 12, 2011 - 7:58 am

    That is really interesting, I thought the main deployment may have been more chaotic, good to know that it’s pretty safe. How did you secure the fin can to the motor and the motor to the upper deployment bay?

  6. #6 by James on November 14, 2011 - 7:19 am

    Both were friction fitted.

  7. #7 by Randy Wiggins on December 19, 2011 - 12:49 pm

    Hate the JB? Are you kidding? And you get it for FREE? JB is awesome. There might be a detractor or two out there but who cares what they think? Have you contacted the company that makes it and told them what you are doing? Bet they would love that. JB, good for your tractor and your rocket! lol Keep up the good work! And thanks for sharing!

  8. #8 by James on December 20, 2011 - 6:34 pm

    Thanks for the kind words and following along Randy.

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