near minimum diameter Ratt hybrid

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Well-Known Member
Jan 20, 2009
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My latest build is a near minimum diameter rocket built around a Rattworks H70 hybrid motor.

The body is 35mm (1 3/8 inch) outer diameter, 31.5 (1 1/4 inch) inner diameter phenolic tube. This is the smooth ground paper phenolic laminate tubes not the typical body tubes. It is a zipper less design.

I machined a cap out of nylon to hold the motor in place It fits into the coupler between the booster and upper section. In the base of the rocket I glued a motor retainer ring. The motor is in tension between the ring and the cap.

The upper half consists of body tube that has a short ring bonded in the top. The avionics sled is machined out of delrin with a spot for the altimeter, screw switch, and battery, the top and bottom are threaded for attachments. Each piece fits nearly net into a pocket, i did have to machine a slot for the altimeter to fit in like a card cage.

A grove machined into the sled provides a wire guide. I machined an o-ring groove in the bottom of the sled to seal it from ejection gas. To assemble the avionics section the sled is pushed up from the bottom until it hits the stop ring, the nosecone with a stud it it then screws into the top of the avionics section holding it snug.

I'm really happy the way it goes together A little lathe and mill work but the avionics 'sled' works well!

altitude full.jpg

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Very nice!

You'll be pleased with the performance you get from that rocket. The RATT H70 is the one motor I've flown the most.

However, I've since moved to SkyRipper hybrids, and need to get back to serious flying.

I have played with some of each,

Rattworks H70
Skyripper K
Hypertek M1000 (did my level 3 on it)
Sims out to 5750 feet,
17 seconds to apogee
485 mph
18 g's max