Wednesday, November 01, 2006

Ready for Recovery

The LOC/Precision Bullet came with a 12' elastic bungie cord for use as the recovery harness. Based on my reading in Modern High-Power Rocketry 2, I decided to replace the recovery harness. I already built in a U-bolt on the forward centering ring in the motor mount, so I can anchor to that rather than use the LOC SCM 1 harness mount. I picked up 3 quick-links from Home Depot and 16' of Kevlar shock cord.

The main problems with the elastic bungie are that it won't last like Kevlar since it lives in the booster airframe (because of ejection charges), it can break easily, and it is elastic and may cause the ejected nose cone to bounce back into the booster and do damage. The main risk with Kevlar is that it could result in zippers if the ejection wasn't timed well or if the shock cord was too short.

I expect to plan my flights using wRASP and RockSim, so I hope to get my timings set good enough to prevent serious damage. In addition, using the 16' of shock cord falls in the guideline of making the shock cord at least 2 to 3 times the length of the rocket so the bodies have some time to slow down before the cord gets pulled.

So anyway - the reason for this post was so I could write down somewhere the weights of the recovery harness. The chute, quick links, and shock cord weight a total of 6.7 ounces. The chute is still the original 36" rip-stop nylon.

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