reusing single use motors?

[rocketsonly]

Hey all. This may sound like a very dumb question; and I'm sure it runs into some sort of regulation.

Has anyone tried reusing a single use motor? For example, getting a spent Estes motor, mixing a batch of black powder and alcohol, then putting the mixture into the motor. The alcohol will most likely evaporate quickly.

Just curious if it would work.

 

[Justy]

NO.

There's a huge section of the rec.model.rockets FAQ on this subject, and here are two paragraphs that directly relate to the technical part of your question.

You can't reuse Estes or other maker engine casings. Spent casings
have undergone considerable stress, they can no longer be guaranteed
to hold if reloaded and fired again. Yes, they have a fairly consider-
able safety margin. It isn't enough to reload them.

You can't use the same stuff Estes uses, nor can you easily obtain
composite fuel. Estes uses black powder - gunpowder - but they are
using a special formulation, not just mixing the usual ingredients.
In fact, it's pretty dumb to use any powder at all. Powder must be
rammed to make it solid enough for "solid fuel" - that means you have
to pour the powder into the casing and then take a stiff rod and ram
it up and down, like one of those old-time muskets. Ramming will
compress the powder - which is the objective - and will also heat it,
which will also make it more shock-sensitive, not to mention the heat
from the friction of the rod itself moving up and down in the casing.
It can also raise dust, which is also more easily ignited than a solid
slug. A fellow by the name of Jim Flis posted a commentary on creating
such engines, I recall. If anyone saved that post, I'd like to see to
see it inserted here.

The full explanation, which is entirely against reloading single use motors on legal, safety and technical grounds, is here:
5.18 - Why don't I just make my own model rocket motors? Shouldn't I be able to custom-make better, more powerful motors, at a cheaper price?

There are people who build their own motors from the ground up; this is called EX (experimental, I guess). I have no experience with this, except for what little I've read from Richard Nakka's page, so somebody else will have to chime in about that. But I do know that reloading spent SU motors is verboten.

 

[DynaSoar]

Originally posted by rocketsonly
Hey all. This may sound like a very dumb question;

You are correct, sir. There are technical reasons having to do with the "grain". But that's not why. It's too dangerous for several reasons.

 

[jflis]

Well.....

I was born "near sighted"... as a result of trying reuse spent motor casings I am far sighted in one eye and have 20/300 vision in both and getting worse.

I certainly wouldn't recommend it....

 

[rocketsonly]

Okay, thanks guys.

 

[Ryan S.]

I wouldnt do it, new casings are cheap.

 

[Stymye]

or if you really want to make your own you could try the Bravo Niner kit

https://www.octoberscience.com/index.html

 

[Johnnie]

I tried the bravo niner kit...every motor I made went BlaM! Blew the forward closure every time...of course it was plain ole hardened putty...I ended up fertilizing my lawn with the rest of the sugar and potassium nitrate propellant...

 

[scm86]

Thought i might chime in here. Yes, they can be reused, but it isnt the best thing to do. See the animated Gif in my Avatar, thats an Estes E case, about 1/4 second after the Gif animation ends, the case slpits in half. cases are cheap, nozzles arent bad either, and good quality cases acn be made from Garolite, availbe from McMaster.

Scott McNeely

 

[Stymye]

I tried the bravo niner kit...every motor I made went BlaM!

I've been tempted to but the kit ...Mabey thats a bad idea

 

[Johnnie]

It was fun work, you get to pack the propellant with a hammer seriously, the kit is a dry ram with a hammer and a cheap wooden dowel. I believe being consistant with the hammer hits was my problem cause any loose propellant actually "flashed" or burned very fast when ignited...BooM! My success rate with singleuse self made motors is 50/50.

 

[MattEx]

I have tried reloading a Quest C motor, leaving the nozzle alone. I made it coreburning with Sugar propellant, dry rammed (as it was simply an experiment, and it works fine in these small motors.

Anyway, my little reloaded motor came up to pressure right away, and made a large cloud of smoke, with a surprisingly loud roar for such a little motor.

After that, I reloaded it again as the casing still looked fine. It worked the same again, but showed signs of the casing almost burning though after that firing, so at that point I threw it away.

It's not really worth it...
Certainly dont reload a Aerotech SU casing .