2.75 in FFAR rocket

[Spaceinvader]

Hello!
I got this 2.75in FFAR rocket motor from my local classifieds for 100$, (inert of course) and its a little dirty so I plan on cleaning it up. The rocket nozzels and the surrounding area is rusty, so that needs a little cleaning up aswell. There is one big problem though, since this rocket has been fired it has some little bits of what I assume is burnt carbon falling out of the nozzles, which is a problem. The rocket base (fins nozzles ect) are held on by a little spring pin. To take it off you push the pin in and twist, but it does not seem to come off. Im looking for any help with getting the base off. Thanks! - Rhys


P.S. I will get some pictures up either later tonight, or tomorrow.

 

[US-Subs]

If it is like most normal US ones, it is not a spring pin, it is a form of a retaining wire. The wire sits in a groove all the way around the circumference between the motor and fins. Typically to pull the fins and strip the propellant you force a small screwdriver under the tip of the wire and lift the end of the square wire out, then pull on it with needle-nose pliers as you twist the fins vs the motor, forcing the wire out of the opening a few mm at a time. On an unfired rocket it can take 10 minutes or so to work your way around, once done the fins can be pulled straight out of the motor body. I've done plenty of unfired in order to pull the propellant, don't think I've ever tried a fired one, never had reason too. I cannot imagine that being fired helps -

 

[HAZORD]

The unfired ones go fast, but the fired ones aren't too bad. I think the wire is behind the O-ring on the non pressure side so it doesn't get residue in it.

 

[Spaceinvader]

Got it! I took out the wire, I dont think im gonna be putting it back in, way to much work. But, al the internals where still in there! This is so cool! (to me atleast!) I was wondering if anyone can identify the parts, I think the long wire is for setting it off, and the big rusted piece in the combustion chamber? Otherwise I dont know what anything else it. The large ring, it seems to be made of fabric or something like that, and some rings that may have been made of rubber at somepoint. I still dont know how im actually going to clean the nozzles, but I will figure something out. Any info welcome! Rhys

 

[HAZORD]

It's hard to tell exactly what your parts are because your rocket is so old. As they used so many in Nam, the internal parts of the powder grain changed. Yours is different from all the ones I've taken apart,that were made in the 60's and 70's.

Your copy has the older style nozzles too. The newer ones have a cant built into them to spin the rocket in flight.


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[Spaceinvader]

Yeah, if it helps at all it is a Mod 1. What should I do with the internals also? I can't salvage any, not even the lead wire, it's rusted to the core. Should I just throw it out?

 

[HAZORD]

I'm thinking you should carefully pack all of it in the smallest cardboard box that will contain it, and then throw it in the outgoing trash.

Looking at the photos on my computer (the phone version was too small), your residue looks like most I've seen. The powder grain probably had a plastic outer coating, and that large chunk is all that remains of it, and some rubber gaskets etc.

 

[Spaceinvader]

That makes sense. Thanks for all the help to both of you, I will be looking for a warhead soon.