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14.2 How do I make my own rocket motors?




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This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.

14.2 How do I make my own rocket motors?

NOTICE:

Many among the readership have an interest in the subject, and discussion
threads about amateur rocketry activities always appear.
Even though the name of the newsgroup, rec.models.rockets, suggests that
the newsgroup is for model rockets only, this is not entirely true. High
power rocketry is a favorite topic among r.m.r. denizens. And similarly,
amateur rocketry is also discussed, albeit in a limited way.
However, questions like:

"What should I mix together so that I can make my own rocket motors?"

are STRONGLY DISCOURAGED. Discussion about rocket motor design and
fabrication is beyond the scope of rec.models.rockets. Most of the
participants of rec.models.rockets buy commercially available model and
high power rocket motors for use in their rockets. Few have the expertise
to instruct you on the intricacies of rocket motor design and construction,
and most likely will not instruct you on rec.models.rockets.
Rocket motor construction is a non-trivial task. It is a task that goes
much beyond merely having a propellant formula with which to use.
You need to know much more than you might initially suspect, and even
then you might make a mistake and get seriously injured or even killed.
Even knowledgable professionals have been known to have accidents.
If you are having difficulty obtaining commercially manufactured rocket
motors, and think that you can simply make your own, please think about it
more, and please give these warnings some serious consideration. Inquire
as to the availability of commercially manufactured motors. Check out the
list of manufacturers in Part 2 of the FAQ.

From (billw@puli.cisco.com)
"I suppose that an article on cheap model rocketry would not be complete
without at least some comment on the sorts of advertisements that read
"build your own rocket engines for only pennies apiece." While I personally
am not the sort of person who would categorically condemn those people
interested in making their own rocket motors, I do feel that model rocket
motors are one of the places where you do get your money's worth. While it
may be possible to build your own motors using only a few cents worth of
chemicals, there is a lot left unsaid. Some of these unvoiced gotchas
include:

1) In order to get to the pennies each price range, you have to buy your
chemicals in large amounts, so your out-of-pocket expenses are high.
2) You have to make or buy various special tools for making the motors.
3) You'll need assorted amounts of safety equipment and test fixtures,
beyond the actual construction tools.
4) You'll need a relatively large land area for your testing.
5) You'll probably be engaging in what the local police will consider
illegal activities, both in making your motors, and in using them.
It doesn't take much of a lawyer's time to cancel out your savings!
6) The finished "cheap" motors are unlikely to have delay or ejection
charges, and will vary a great deal from motor to motor in performance.

"I'm also interested in amateur pyrotechnics, and recently bought a copy of
"The Best of American Fireworks News, Volume 2." There are a couple of
excerpts in there that are particularly telling. One article mentions using
commercial A8-3 rocket engines as a "quick and easy way" to make skyrockets.
This is followed up by another comment that includes:

"I have made rocket engines from scratch for years, but
have just recently discovered that the time savings,
reliability, and better performance of commercial engines
make them a viable alternative."

"These are discouraging remarks for the would-be motor maker, but the most
important reason NOT to make your own motors is implied in item (5) above -
"Model Rocketry" enjoys certain legal exemptions because it has shown itself
to be an exceptionally safe hobby over the years. If you make your own
motors, you are no longer protected under those exemptions - you are no
longer participating in "Model Rocketry". If you happen to have or cause a
major accident, the press won't be clued in to this distinction, so aside
from the people who actually got hurt, the reputation of the hobby will be
damaged, and we'll be another step closer to having model rocketry outlawed."


Have you read Part 1 of the FAQ yet? Here are a few repeat items to
consider:

From Buzz McDermott (buzzman@netcom.com)
"Finally, the editor of this document wishes to get on his soapbox for
just one moment and add the term 'stupid rocketry' to cover all those
who attempt to casually produce their own rocket fuel and/or motors
without the benefit of very serious study, and implementation, of the
processes involved and safety measures required. Especially note
that this comment is NOT aimed at serious amateur rocketry
organizations, college level research, etc. End of soapbox."

In summary:
The bottom line is that rec.models.rockets is primarily a newsgroup for
discussing *consumer* rocketry (which covers model rocketry and high
power rocketry). Some amateur issues are discussed, but these are not
the primary focus of the group. Manufacturing your own rocket motors can
be a very dangerous thing to do, unless done properly, and with extreme
care. The odds are you will not make motors that are of any higher quality,
total impulse, reliability, or cost less than pre-manufactured consumer
rocket motors.

It is the opinion of the editor(s) of this FAQ that you should NOT try
to manufacture your own motors. If, however, you insist on partaking
in amateur rocketry, then the editor(s) of this FAQ urge you to get in
contact with an established amateur rocketry group for guidance and
assistance.

 

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