AboutJames Bell Expertise I am a member of Tripoli Rocketry Association, and am certified to fly hi power rockets. I can answer questions anyone may have about design, materials selection, stability calculations, motor selection, altitude and performance predictions, and parachute and recovery options.
Experience I make my rockets from existing kits or parts readily made through commercial channels. I do NOT make my own motor propellants (they are challenging enough even for the companies that do this for a living), and I do not advocate making rockets using "typical household item" such as paper towel rolls.
Question I have a kit for a Mean Machine and would like to make it one body tube section shorter (18"). Personally, the rocket as designed looks too skinny and fragile. With this modification what concerns do I need to address about flight stability or any other situation I have not considered. I have never designed rockets but am interested in doing so.
Thanks for your help!
Answer Kerry -
With the exception of some additional fin area, the Mean Machine is not much more than a very long version of a Big Bertha. You could safely go down to a single tube length and still have a stable rocket.
I built a Mean Machine many years back, early on in my rocket building hobby. I was still using Elmers glue and the sections "sagged". It curved and formed kind of a bow shape. It still flew pretty straight, but looked really funky. When you build yours, regardless of how many tube sections you use, be sure to use epoxy (5 to 15 minute). White glue is very susceptible to moisture absorption when the humidity is high, which causes the joints between the long sections of rocket body to sag.
If you are interested in learning more about designing your own rockets, I have a webpage set up at ...
There is a book listed there, The Handbook of Model Rocketry, by G. Harry Stine. It is the source book I use to assist me in designing my own rockets. The site will also give you links to places where you can get rocketry components to build your own, plus an altitude prediction program so you can take existing rockets and see how high it will go with various different motors.
