Ye Olde Rocket Forum - View Single Post - Scrounged-Up Designs 2006

Here's a two-fer plan. You can build this model for 18mm motors exclusively, or build it for 24mm motors and use an adapter for 18mm. RockSim says the model is flyable on the 18mm "C" class motor, but you will need a 48" launch rod as this motor does not have enough initial thrust to get the model going quickly. The 24mm "C" has just the right spike to get it moving from a 36" rod.

You might get better results on the 18mm version when (or if) the 18mm "D" BP motors are released into the wild; higher-impulse 18mm AP "C" class reloadables are also a possibility.

Using the "C" class motors, the altitude is under 600' and thus qualifies for the "VR Class" designation. The "D" motor gives the most impressive performance at just over 1000'.

Length: 30.5"
Diameter: 1.64"
Fin Span: 5.04"
18mm Weight: 2.96 oz
24mm Weight: 2.72 oz

C6-5.......532'......Dv 26 FPS......48" launch rod
C11-5......516'......Dv 12 FPS......36" launch rod
D12-5.....1007'......Dv 16 FPS......36" launch rod

Addendum: Yes, I'm looking into a re-design of this model already. The idea of a central core ST-10 with an ST-16 outer sleeve makes more sense construction-wise than the current plan of having the ST-5 stuffer tube. It also allows more room at the top for the parachute. The current version limits the amount of wadding you can put in the tubes. The overall weight of a longer ST-10 should balance out the weight of the additional rings needed for the ST-5.

Enjoy!