Saturday, May 23, 2009

A Really Big Pair

I finished making these 2 nozzles for longtime rocket buddy, Don C., a few days ago.  They aren't the biggest nozzles I've worked on, I once helped design and produce a 2 piece nozzle that was 8" dia., but these are the biggest that I've CAD designed myself and turned on my own lathe.
Eureka! ZZakk's Lab has produced monsters!  Bwa-ha-ha-haaa!!!  

Ahem, in the lower pic they're posed with one of the Cesaroni Pro98 motor cases that they were made for, and the fabulously expensive spanner tool that Cesaroni now sells for installing the retainer rings.  Actually, just about anything you need or want for 4" rocket motors is fabulously expensive. The Cesaroni cases are designed and licensed [fabu dinero, I'm sure] to operate with Aerotech reloads as well as Cesaroni reloads.  This is a good thing since it increases the versatility of the hardware.  My friend however, is currently making his own Moonburn reloads for the cases, and using RCS/Aerotech supplies in the process.  The RCS 98mm nozzles are $44 each for a single use, and in the case of the 5/8" throat on the right, would still need to be custom bored anyway.  My graphite nozzles are completely reusable, and if need be, I can remachine the throats later if they get too crusty, chipped, or a larger throat is desired.  Some internal fuel volume is sacrificed but I added a much better expansion ratio, between 5:1 & 6:1 instead of only 2:1.

Last year, I looked long and hard at the costs of larger motors.  I decided to go with 3" hardware since it costs less than 4" every step of the way, despite the longer length needed for the same power.  Plus, being a hybrid flyer, a 3" combustion chamber is plenty big enough, AND, I'm already used to building rockets that take relatively long motors.

More recently, I rescued a belled 3" case from another friends recycling pile. Thanks RK!  

I trimmed the ends off, but still need to cut new snap-ring grooves.  It's kinda short, but I'm on my way!  When I get around to buying new 3" motor cases, I'm gonna give the
Cesaroni hardware another good look.

1 comment:

  1. I almost titled this post; Porno for Pyros.

    Wasn't gonna say this out front.
    I wanna walk around at a launch with those nozzles in the big front pockets of my cargo shorts.