LOC Cyclotron modification. Move CG forward.

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Well-Known Member
Jan 6, 2016
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This is more of a general question. I've built a LOC Cyclotron for my up coming level 1 attempt. This is the biggest rocket I've built to date and my first foray into the world of 38mm.

Thinking about future possibilities... (in other words, I still have some money left in my wallet)... I was playing around with rocksim to see what a J motor would do in this rocket. Then I looked at modifying the rocket (after a successful L1 flight). I can add another 8-12+ inches to the main body tube to move the center of gravity forward to allow for bigger motors. If you just extend the body tube, the CG should move forward faster than the CP I assume.

Questions: In general, why would you make the body tube of a rocket kit longer? What is the motivation, advantage, or disadvantage?
Is it better to make the body tube longer or just add weight to the nose cone to migrate CG forward?

Any advice and/or experience appreciated.


Amateur Professional
Jan 30, 2016
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It's literally a balancing act. Consider an underweight airframe: it will accel and decel harder, limiting altitude but having a higher top speed. Too short understable, too long overstable (wind will really swing it around) and draggy.

Many rockets tend to fall in the range 5-10x as long as they are wide due to these (and many other) constraints.
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More Rockets Than Room
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Aug 18, 2012
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Athol, Massachusetts
If you plan on putting a J in your Cyclotron,( providing it holds together)you'll most likely want to do Dual Deploy. The added weight of the parachute and other recovery gear should bring your CG ahead enough. That being said, the payload section on the Cyclotron is a little small for DD, you'll probably have to add to your current payload section or build a new one large enough to hold your recovery gear.
I used a Cyclotron for my L1 cert and has been flown many times since.