Monday, December 21, 2009

Kick-off: 7.5" Der Red Mix

This will be my first scratch-built, upscale design. As a kid I built the 1.6" diameter Estes kit "Der Red Max" and found the design appealing and the decals amusing. I'm not a fan of huge fins so on my design I've taken the liberty of scaling them down to just enable a static margin of 1.16 with the heaviest motor array (L935, 2xJ530, 4xI224). While 1.16 might sound low for a cluster I've learned to trust RockSim's stability equations and find the original Barrowman equations to be too conservative. Also I'm not likely to fire the cluster on the ground and will probably always start with a powerful 54mm motor to send the rocket up and away before igniting outboard motor pairs. Here are some screengrabs from RockSim 9:
I'm still working out the details of the electronics bay but I plan to seat a removable trap door just above the fin tops to conveniently seat two multi-function altimeters and a Flip MinoHD video camera. The onboard video should rock! I've slowly been buying components for this design from Jack at What's Up Hobbies as well as Loc Precision. I also ordered my first set of laser-cut fins and centering rings from Balsa Machining Services and an AMAZING set of decals from Mark Hayes at Here's the array of parts pre-assembly:
The fins are only 1/4" thick so I'll reinforce both sides of each with one layer of 6 oz carbon fiber to improve rigidity. Having just cleaned my garage I plan to start on this build ASAP!

1 comment:

KO said...

i like the bad ass skull decal