Ex

[Gunkie]

I'm thinking about building some EX motors. I've purchased and basically read both the CP Technologies (AN advocate) and McCreary (AP advocate) books. Very interesting stuff, especially in light of the vast array of high quality, manufactured HW components available, specifically casings and nozzels. In addition, I plan on taking the Loki Research motor making course in the near future.

I suppose I'm looking for some insights from experienced EX'ers into what I should expect. I already know some of the basic things like 'don't mix dry oxidizer and dry metal powder together'. Very bad.

Is it all worthwhile? Where do you do your propellant mixing? I'm planning on doing it in a detached garage. Should I get a big canvas tent instead? Anyone ever have a flare up or unwanted ignition of propellant or slugs due to drilling cores, pulling core rods, cutting slugs, or mixing ingredients?

Maybe I should just take the class and figure it out myself?

Thanks from a potential EX'er.

 

[AlexNUMB]

Hi Scott--

It sort of depends what your after, I guess.

I've been involved in HPR since I was 14. Back when TRA confirmation for minors was still legal.

I sort of drifted away for a few years, came back, yaddah yaddah same ol' BAR story, just a compressed timeframe.

Getting into formulating, casting, testing, and (finally) flying them was a long road. I spent a year reading books, watching over people's shoulder while they mix, etc. But it was something I was truly interested in.

I wanted to know what the chemicals that went into them were, Why BATES grains were easy to use, how to make a real fast burning motor, etc. I wanted to understand the fundamentals of how our motors were producing the usable thrust that they were producing.

I also like variety. For a long time there, Aerotech produced WL, BJ, and BT. Sitting on a field for 3 days straight watching the same plume of white exhaust started getting a little old for me. I wanted to fly sparky motors, green motors, blue, etc. (With the advent of AMW, this point is now sort of moot)

I also like flying BIG motors. Ms Ns Os Ps.... the bigger the better. It's probably a function of the fire/smoke macho factor, but it's what I wanted to do.

Flying big motors takes big money. I couldn't concievably justify $320-$500 per M motor. So saving money on the larger motors was also a factor for me, but it wasn't my driving factor. (I'm saving money on the larger loads, after you know, $1000 in tooling or so... ;-) )

I mix in a garage. I've never had an unintentional flare up from any kind of propellant I have tried (although I would be careful drilling out the cores of Ti flavored sparky motors). I follow McCreary's safety guide and keep my mix area exceptionally clean. I don't allow mixing residue to build up at all. If you follow McCreary's safety guide, you shouldn't have any safety related problems. (knock wood)

As for how to get started, I have never taken a class before, so I can't comment on that. I have met Jeff Taylor (Loki Research) and I can say that he is extremely knowledgable and makes great hardware. His ARTS is also real good. I would bet that his class is really good....

I am blessed in the sense that there are several really knowledgeable folks in my region that have mentored me and helped me to get started. Our area has a very good support group that helps each other out quite a bit. I would suggest buddying up with someone in your area who can show you the ropes safely and who can put up with stupid questions (I know I asked an awful lot of them when I started!).

Hope that helps... I am still on my EX journey and having a great time doing it!

--Alex

 

[Gunkie]

Wow! Thanks a lot. This is what I was looking for and it clears up quite a bit for me. I'm going to press forward and keep an eye on safety, expendatures, and ego. I plan on starting with basic formulations in 38mm HW.

Thanks again!

 

[MarkABrown]

Hi guys. Good discussion. Just a reminder, don't discuss specific propellant formulations in here. Discussions about safety procedures, calculations, and thrust formulas are OK as long as the don't refer to actual chemical compounds.

BTW, I've been mixing my own propellant for almost 2 years now. It has really added an amazing amount to the "interest factor" for me. Experimental rocketry is very expensive to begin, since most of the necessary equipment is not something that most rocketeers have handy. However, once the initial investment is made, I believe that it is possible to actually save some money on motors. It's gonna take a long time to amortize those startup costs though.

 

[Ryan S.]

however, once you relize you arent spending so much per motor you make more motors and only end up spending more money

 

[Rocketmaniac]

Originally posted by Ryan S.
however, once you relize you arent spending so much per motor you make more motors and only end up spending more money

shhhhhhh, don't let the wifes here this kind of talk...... EX motors are something I want to get into and the "cost" is the main reason