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Old February 2nd 07, 05:22 PM posted to
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Default Need help with a rocket motor ID

On Fri, 2 Feb 2007 18:38:32 +1030, "Dave Kearton"

I've just received a few pics of a small rocket motor, from a friend of

It's about 2Kg and about 45cm long with a 10cm wide nozzle. It's a
liquid fuel motor and doesn't look like it has any electrical connections.

Well, I have looked at my share of rocket stuff, and you sure have me

First thing I notice is that the combustion chamber seems quite long.
That is always a compromise but usually they wind up being shorter too
much shorter than this.

Second is the helical wrap of the flow passage in the thrust chamber
wall. It is obvious what they are doing there, but I never saw one
like it, except maybe on the back of an envelope.

The nozzle looks to be maybe a 25 to one expansion ratio, so it is
designed for vacuum conditions.

The lip on the nozzle skirt looks very thick to me. Usually
spacecraft nozzles are very thin at the lip. I have been much exposed
to nozzle lips that were maybe a meter in diameter that were not that

It looks American, not Russian, but sometimes that is hard to tell.
No. xx495 has some writing in it. Looks to me like part of it says
"Sy6xx". So, it isn't Russian, I guess (they get along without those
letters). The "y", if that is what it is, is very funny shaped.

Any writing is very important for ID's.

(I remember many years ago there was a paper in some technical journal
which was written by some Australians in which they described an
object found in the "outback". They considered whether it might be a
bit of reentered space debris. Part of the description was an ink
stamp of a small circle with "CVA263" inside it. That is a "Convair
Astronautics" inspector's stamp. I was convinced already.)

The tube fittings are typical AN, American "Army/Navy" standard ones.

The propellant lines are about the same size, probably lox something
or hypergols, no hydrogen.

It might produce a thrust of a few hundred pounds, a bit large for
reaction control.

We're all guessing it could be some form of reaction nozzle for (maybe) a
Gemini or Apollo capsule.

I am not familiar with all the thrusters in those spacecraft, but I
will bet that this is not one of them.

For one thing, just as a general observation, "the further up the
stack" you go, the bigger the "dollars/pound" trade factor becomes,
and the more "sophisticated" the hardware looks. Even if it saves no
weight, the designer will try to make his part look more expensive so
that it goes with the surroundings. But, sometimes, a "boat anchor"
manages to sneak onboard. This think looks to me like a piece of GSE
or a test article that may have flown on some "primitive" vehicle.

I will also say with some certainty that it doesn't belong to an
Atlas, Thor, Delta, or Saturn vehicle.

The Atlas had a Rocketdyne thruster somewhat similar in size; it
didn't look anything like this.

And, I don't think it is from Rocketdyne.

Can I buy a vowel please ?

My first suggestion would be an "A".

As in "Aerojet". They built a lot of stuff I don't know about. But it
doesn't really look Aerojettish, either.


I am very interested in what you find out.

Henry H.