A Beginner's Guide To American High Power Rocketry
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Please be VERY careful in regards to making your own motors. Maybe 3-5% of the rocket community does this and for good reason: There are very real safety risks in making motors. The processing of very fine metals and oxidizers requires well defined handling and safety procedures otherwise there could be catastrophe. That said, it can be done safely and the community is vibrant. My suggestions for you if you eventually want to go down this road:
- Join Tripoli if you haven't already.
- Certify Level 1 and Level 2. You will need to be at least Level 2 to launch research motors at a launch regardless of the class of motor.
- Join the Research community here on TRF. You need to request access. Start reading.
- Find a mentor in your area that does EX motors. Get them to show you the ropes and mentor you.
- Before you start mixing, make sure you have proper safety procedures and PPE in place and available. I can't stress this enough. You need to be careful and adopt a professional approach to mitigate the risks involved.
Ummmmmmm, compared to making fireworks, APCP is significantly safer because you add powders to liquids and wet them out. The major cause for concern is the bits and pieces left over from drilling 38mm grains and such. In the shop I've been in the
bits are collected after every grain drilled and burned off safely at the end of the session. Don't allow the powder and shavings to accumulate in the work area. When we've burned off a few pounds, we can feel the heat from the flash from
100 feet away. Making motors lends itself to a group social setup. Each individual can do tasks along with rocketry BS and banter. This is a great way for new persons to learn the techniques.
Kurt
bits are collected after every grain drilled and burned off safely at the end of the session. Don't allow the powder and shavings to accumulate in the work area. When we've burned off a few pounds, we can feel the heat from the flash from
100 feet away. Making motors lends itself to a group social setup. Each individual can do tasks along with rocketry BS and banter. This is a great way for new persons to learn the techniques.
Kurt
That is almost correct. You have to be Tripoli L2 to fly at a Tripoli sanctioned research launch. There are no restrictions or level requirement to make or fly your own motors. NRA and Tripoli has nothing to do with making your own motors. Tripoli's only requirements come into play when you want to fly at one of their sanctioned launches. If you want to make your own motors and fly them in Class 1 rockets (less then 3.3 lbs and less then 4 oz of propellant) you can fly them anywhere without FAA waivers or any other requirement, as long as it isn't a sanctioned launch. If you get your own waiver, you can fly anything that fits the waiver and technically, you don't even need a certification. Of course you will be insured only to the level your personnel insurance cover you.
With that said, most folks making and flying their own motors do so as L2 or L3 at Tripoli research launches because of the waiver requirements and club insurance. Also, if you are going to commit enough time and money to buy the equipment and chemicals to make your own motors, spending what you need to get your Tripoli L2 is a drop in the bucket.
Kurt is right, making your own motors is much safer then making fireworks because of the processes used. Some guy love the electronics, some creating fantastic paint jobs, other are altitude junkies, other love big and slow. Making motors is just another aspect of rocketry and has it's different things you can concentrate on too.
My final thought on all of this is that rocketry is as much a social endeavor as it is technical. I don't think I would even be doing rocketry if it wasn't for the people in the club and at the launches. Sitting and swapping stories and experience is as much a part of rocketry for most people as actually flying the rockets. Also, if you are making motors, mixing parties can happen even if the weather doesn't cooperate.
My advice, find a club and join in. Have fun!
cherokeej
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The OP is new.
Welcome to TRF and rocketry.
A better guide to high power rocketry would be Mark Canepa's book, Modern High Power Rocketry 2. Good reading. Can't recommend it enough.
Making motors is for the considerably more advanced rocketeer that has the necessary background. It is strongly recommended that you leave that to those qualified individuals.
Welcome to TRF and rocketry.
A better guide to high power rocketry would be Mark Canepa's book, Modern High Power Rocketry 2. Good reading. Can't recommend it enough.
Making motors is for the considerably more advanced rocketeer that has the necessary background. It is strongly recommended that you leave that to those qualified individuals.
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That's a great start! The Canepa book MHPR2 is handy for moving up to HPR, except the electronics section is a bit dated.
Zeus-cat
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There are a number of threads where people talk about making motors. Note that discussion of formulas is strictly prohibited in the public forums.
Anyway, the consensus is that if you are thinking you are going to save money by making your own motors you should forget about that right now. I know someone who is L3 in Triploi and makes all of his motors. Now he does save money by making his own motors, but he makes big motors, and he makes a lot of them. Scale of economy works for him because he can purchase chemicals in bulk and he uses them before their shelf life expires. He makes mostly M size motors. You won't be saving money if you are making smaller motors and just a few of them a year.
If this is something you are really interested in be prepared to spend money on the proper equipment to mix chemicals, the chemicals and other supplies. Your best bet is to find a person or group that is already doing this and join them. Most likely they are Tripoli L2 or L3 and should expect you to get that certification before joining them to make motors.
Anyway, the consensus is that if you are thinking you are going to save money by making your own motors you should forget about that right now. I know someone who is L3 in Triploi and makes all of his motors. Now he does save money by making his own motors, but he makes big motors, and he makes a lot of them. Scale of economy works for him because he can purchase chemicals in bulk and he uses them before their shelf life expires. He makes mostly M size motors. You won't be saving money if you are making smaller motors and just a few of them a year.
If this is something you are really interested in be prepared to spend money on the proper equipment to mix chemicals, the chemicals and other supplies. Your best bet is to find a person or group that is already doing this and join them. Most likely they are Tripoli L2 or L3 and should expect you to get that certification before joining them to make motors.
Kurt,
I agree with your qualified first statement. Always starting with liquids and properly wetting out powders are best practice and good procedure. When you follow that protocol the risk is reduced significantly. Safely handling your leftover powder and shavings is another procedure that when implemented reduces the risk.
However, I have seen people mix oxidizer and metals dry before and spew clouds of atomized particles into the air. I have seen piles of shavings not properly handled that have posed fire risk. I've seen people drilling and using a chop saw when cutting sparky motors. Either people don't know about the risks or don't care.
I am not saying don't do it. I encourage the OP to experiment with motor making if that is a goal of theirs. My Main Point for writing that post was and still is before you get started, get some help/guidance to ensure that you have the proper procedures in place to reduce the main risks involved to those around you.
Here's the link to that book.
If you want to make motors, McCreary's book Experimental Composite Propellants is a good practical starter reference. If you want a college level technical reference get Rocket Propulsion Elements.
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Right, No, no, no, mixing oxidizers and fuel dry. Fireworks people do that but they have to be extremely careful. That is poor technique for APCP as you mentioned. This is where mentoring comes in. Yes one isn't going to save anything making their
own motors by themselves unless they fly a lot of L's or greater. Would take time to recoup the investment. One can see some savings if a large group goes in on a setup and spreads the costs out over several people. At a group mix, we're aware of the recipe beforehand and bring some "fix'ins" to toss into the bowel. Pack the grains and all are happy.
I don't see any mixes being inappropriately discussed here and there is nothing wrong discussing general safety on an open thread.
Chop saws? I've witnessed it but besides being outside in a very open area, there are some significant precautions that need to be taken and is not recommended for a neophyte. "No cutting sparkies with a chop saw" rule is a good one but...........
I am aware of a posting (but didn't witness) where it was stated that a remotely controlled saw was setup and the task was carried out without mishap. Why no sparkies? The components in the grain lend a spark risk and that is not too cool.
Again, using a chop saw will entail a lot of further precautions I won't go into as I don't want to see any neophyte doing it. If they learn under the tutelage of a mentor so be it. I think the teaching should entail witnessing the
controlled disposal of a burnpile at a distance. If that doesn't build respect I don't think anything will.
I've been told a major maker uses a device that is like a rotating pipe cutter to slice grains. Nice technique.
One has to always, always think safety to avoid getting burned, literally. Kurt
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I don't get the "Not a cost savings unless your making M's" argument. It costs me $10-15 in chems and liners to make a 2 or 3 grain 54mm J. Retail cost is $70. I tallied it up and I have about $450 in all new equipment including the sage mixer, casting sets and mandrels, disposables, PPE, Burnsim, and 54mm 3g hardware. My break even point was 7 motors which is 1 launch for some people. If you add a characterization setup to that cost it's a little longer but you can still break even in one flying season. With M's you certainly break even faster but it's still cost effective for lower impulse sizes. If you can split the equipment costs the payback is even faster.
This isn't the main reason I make motors, but it certainly helps that you can make them cheaper.
This isn't the main reason I make motors, but it certainly helps that you can make them cheaper.
If one goes out and buys mixer, materials, vacuum pump. curing oven if needed, fittings, bowl lid, vacuum tubing,gauges and various tools, that can be quite a layout. Add all the stuff required for characterizing propellant and the cost goes up accordingly.
Sure you want to hand mix without vacuuming or characterizing you will be limited in your particular choices and it can be on the cheap...... Unless you start blowing your cases and can't machine your own hardware.
The reason to mix is the satisfaction that one can do it and have nice flights with something "you" made. Not to go out there and think they can do it cheaper and better than the commercial makers. Kurt
Sure you want to hand mix without vacuuming or characterizing you will be limited in your particular choices and it can be on the cheap...... Unless you start blowing your cases and can't machine your own hardware.
The reason to mix is the satisfaction that one can do it and have nice flights with something "you" made. Not to go out there and think they can do it cheaper and better than the commercial makers. Kurt
Forgot the vacuum stuff because I already had it when I started. I knew something slipped my mind. Regardless, the ROI with a full setup is still there. I agree with your reasons to mix. They aren't the only reasons. I got back into mixing so I could develop motors with customized flight profiles for some of the high performance projects I want to do and conduct dozens of field tests of some of the systems I want to develop without breaking the bank. Others mix so they can fly huge rockets on huge motors that they couldn't otherwise obtain. Some mix because they love chemistry.
Everyone has their reasons. I was just pointing out that ROI is there if you fly a lot.
Everyone has their reasons. I was just pointing out that ROI is there if you fly a lot.
Well he's dead now, BP was king then and actually is more dicey to deal with. I shiver when I see some of the "rocket motor making kits" that have one hit a piston with a hammer to compress the BP mixture.
APCP was developed to be safer to handle and make. The risks are much more manageable in this modern age. Nate's comments are very valid though, only the documentation lacking is a step-by-step
data reduction protocol for characterization. Yeah, the equations are out there, the gist of curve fitting is out there but no one has written a comprehensive tome for the less mathematically inclined to
a method to produce valid data. There are a lot of pitfalls to this process one of which is getting a consistent product without voids or microbubbles. The deeper one delves into this subject the more
work involved for a reproduceable result.
I had corresponded with Dr. McCreary in the past about the lack of a step by step and he was going to work on it in the 2nd edition of his book but health issues intervened unfortunately and was not completed.
Nothing wrong with "bought motors" but I've had more CATO's actually with the commercial stuff, burn throughs mainly than with my research stuff. Granted I don't fly as many research motors unless
I've tested the heck out of them first. (Dr. McCreary attested he did the same thing. Ground tested a lot before he flew it.) Mass testing is easier to swallow because the cost of the motor materials lends itself to multiple tests. Get the motor dialed in and will likely fly nominally especially if made up
from the same batch that was used to test. Video testing is a lot of fun as long as there is a nearby open area away from people. Nozzle up, into the ground, video camera up close and stand way back for remote
ignition. I built a wireless RF ignition setup so I can be waaaaaaayyyyyyyyy back if I like. Don't necessarily have to go to a launch site to do a motor ground test. It's fun to do.
Kurt
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