5 replies to this topic

[Mortartube]

Here's a photo of a Brocks Neptune Rocket with original box from the nostalgia treasury, probably mid 1970's.




And here it is in it's component parts. Notice the resin cast stars, which were cast on a rubber mat with a slightly raised grid pattern, using resourcinol resin. When the resin had cured, the mat was placed over rollers and flexed so that the stars broke into regular squares. The stars are about as thick as a 10p piece.



The motor is also resin cast. I think the motor casting may contain iron as their looks to be small specks of rust in the mix. Here's an image of the size of the stars. There are two lengths of match to aid ignition, nobbly owing to the size of grain powder they were dusted with. Proper UK match, not the smooth stuff now available.




Excuse the slightly out of focus pictures, I don't have the best digital camera for closeup work.

[Mortartube]

Sorry about the huge images, this is my first time posting pictures and it all went a bit Pete Tong.

[EnigmaticBiker]

I'd never of guessed the stars would be flat and square.
Interesting manufacturing details.

[Jerronimo]

You say the motor is also resin cast, it would be nice to know how they did that, what comp. they used and with what binder.
And how they overcome the problem of schrinkage of the propellant grain.
It would be awsome to have a bp based castable propellant, as it would ommit the endless ramming and pressing of rocketmotors, and give more consistant results I think.

[Mortartube]

I'm not sure of the motor composition. I only have the information about the star casting from an ex employee of Wells who IO believe knew some people who worked in Sanqhar for Brocks.

I know that resorcinol resin has very little shrinkage and a quite fast setting time as I've used it in boatbuilding. It's quite dear, I think the last lot I bought was made by Humbrol. You probably only use a small amount 5% or so I'm guessing or you start to impede the burn characteristics of the mixture.

Here we go. It is apparently 670 grammes when mixed

http://www.axminster...-Glue-21681.htm

And here's the safety data sheet for anyone who might consider using it.

http://www.tooled-up...TBCASCOPHEN.pdf

Edited by Mortartube, 28 October 2006 - 10:21 AM.

[Mortartube]

I found this as a kit on Firefox and I'm guessing the Brocks motor contains the same or similar. Note the Ferric Oxide burn rate catalyst, I can see rusty looking specks in the motor casting.


PROPELLANT PACKAGES:


HTPB & PBAN PROPELLANT PACKAGES
EACH KIT INCLUDES ENOUGH MATERIALS TO MAKE APPROX. 6 LBS OF PROPELLANT WITH CHEMICALS LEFT OVER! SIMPLY PURCHASE MORE OXIDIZER TO PRODUCE UP TO 75 LBS OF PROPELLANT!

THE HTPB KIT COMES WITH THE FOLLOWING:

142 PG. MANUAL - "PLASTIC RESIN BONDED ROCKET FUEL SYSTEMS" - VERSION III
1 GALLON R-45 HTPB, RESIN, HYDROXYL TERMINATED
1 QT 2-ETHYLHEXYL ACRYLATE, LIQUID PLASTICIZER
8oz ISOPHORONE DIISOCYANATE, CURATIVE
8oz HX-878 BONDING AGENT
1 LB FERRIC OXIDE, BURN RATE CATALYST
2 LBS 200 mic AMMONIUM PERCHLORATE, OXIDIZER
2 LBS 90 mic down superfine AMMONIUM PERCHLORATE, OXIDIZER

ALL THIS, A TOTAL VALUE OF OVER $110.00!

YOURS FOR ONLY $103.00!!