Sunday, April 25, 2010

Der Red Mix's precise design

Last night and this morning I worked up several templates based on my size/position guide (click image for larger version):
As this will be my most complicated scratch-built design ever I found it necessary to plan all the part positions precisely up front. I highly recommend either Illustrator or CAD for this purpose and I used the former in this exercise. I just need a few more parts and I can start cutting and adhering.

Saturday, April 10, 2010

Repair day

After finishing my taxes today I decided to repair several ailing rockets despite needing to build/finish several others.
First off I fixed the 4" bullet after an early I366 Redline flight with yet another incredibly short delay. That was the last of the Redline motors I bought 'round about 2002 and, even storing the delays separately, these old motors accelerate the delay burn by roughly 6x. As such the ejection charge blows even before the motor has burned out (and yes I'm certain I assembled the motor correctly). This is the third old Redline that's behaved the same way so I sense a trend. The bullet suffered a zipper about 1.5" long right through the carbon fiber reinforcement so it was going damned fast at the time. Luckily I had enough room above the coupler that I could just slice the zipped section off and the nosecone still fits unmodified:
If this rocket suffers another event requiring repair I'm cutting my losses and tossing it!
Secondly I'm trying to correct a warp in my Viciously Mean Machine's 48" payload section. I'm quite certain this happened during carbon fiber reinforcement due to inadequate support while curing in the oven. Today I taped a 10lb. weight to the high point in the tube, suspended it in the curing oven on a contiguous 1" dowel, and post-cured for roughly 35 minutes. I'll check it in a bit but if that didn't work I might be scrapping a second payload section. Dammit:
Finally I had experienced a wall deformation in my 7.5" Nike Smoke on its last M1939 flight. I'm quite certain this was because I flew it single-deploy and, when the 16 foot Rocketman 'chute inflated from the payload section, the payload coupler came out an an angle and cracked/deformed the top of the tube. I mixed up a batch of West Systems epoxy, dropped in a liberal amount of Kevlar pulp and white pigment, and slathered that mess on the inside of the tube. I then used packing tape on the bottom of the tube to prevent leakage, topped it with a sheet of vacuum bag film, laid in a section of 7.5" tubing, and clamped the whole thing together. I think this will work pretty well after I grind off the excess epoxy:
I'm way behind in my blog posts so I'll list what I still owe here so I don't forget:
  • March Plaster City launch report
  • April Plaster City Launch report (featuring 9,140' I284 flight which I think is a record)
  • Inexplicably wacky ARTS2 altimeter behavior
  • Mad Cow Squat build (due before LDRS 29 in early June)
  • 2000MPH President's Challenge build (Due before May Plaster City launch)
  • Der Red Mix build (Due before LDRS)