Upscale Big Bertha

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Oct 28, 2004
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Bought a 29mm casing and now I need something to fly it in. I've had great results from a standard Big Bertha bashed to 24mm, so I'm exploring the logistics of a BT-80 Big Bertha to fly the Aerotech 29mm reload. Any and all advice appreciated (and possibly heeded.) What's a good source for 29mmID tubing for the motor mount? Does anyone know a mail-order source for ripstop nylon for making parachutes? Since I'll be using two 14-1/4" lengths of BT-80 tube, should the rocket separate in the middle or pop the nosecone for recovery? What size chute should I use? I plan to use 1/8" plywood for fins and centering rings, with an aluminum positive motor retention ring. Thanks for the good advice!
The Super Big Bertha kit has all the bits pre-cut

i substituted a LOC style, heavy walled 2.6" tube for the wimpy extes bt80 for long term durability. Stock fins were used. estes' 24" plastic parachute brings it safely down. I also put in a modular MMT made from coupler tubes so i can fly any combination of motors that can be made to fit. so far, the most powerful motors it has flown on are F20 EJ motors.

one of my favorites!
I agree with Rob's approach using thicker body tube. I used Estes BT-80 for my upscale about 5 years ago. It has a 24mm motor tube since I had just bought a 24mm RMS casing back then.

With the Estes tube and balsa fins soaked with thin CA she has successfully flown on all of the Aerotech 24mm reloads. The only problem came on an F39 that wrinkled the body tube slightly where the forward ends of the fins meet the body tube. Thicker tube would certainly be better.

I think that if I make another one I would go to a 29mm motor tube so that I could use single use or Econojet motors. It would be sweet on a F20 White Lightning!