29mm Aluminum Reloadable
I was very bored one day and happened
to come across some diagrams of reloadable rocket engines, thought the
project looked like a good way to spend a few hours, so I decided to
give it a try. First I started with some 6061-T6 Aluminum Alloy tubing
with a 1.009" ID and a 1.125" OD, and cut it to a length of 7 inches or
so (don't have exact measurements with me right now, but I remember it
being approximately 7 inches)
6061 Aluminum alloy is what is
typically used in the aerospace industry, since is extremely strong,
lightweight, and also very machinable. Out of all the aluminum alloys I
have worked with (including home-forged alloys), 6061 is by far my
favorite. It machines beautifully. Now that the tube is cut to size it
is chucked in the lathe,
and the ends are turned down to make them
square, smooth, and to get rid of the roughness of the hacksaw cut.
From there a boring tool is used to bore a 1/8" wide, and 1/6" deep
groove inside of the tube on both sides about 1/4" in from the end of
the tube; This will be used to hold some internal retaining rings in
place, therefore holding the engine together; so it is an important
of the motor. Wow, I'm terrible at explaining this.... Ill let the
picture below better serve you.
Above you can better see what I was trying to explain. So on the other
side of this tube is the same exact thing to hold the aft (rear)
retaining ring. Realizing I did not have the proper tools to put in the
snap rings I earlier bough from the HomeDepot, I quickly ran to Harbor
Freight Tools, my source of cheap Chinese tools, for when I'm too cheap
to buy the good stuff. Since this is the only thing I will be using
retaining ring pliers for, I figured buying the cheappies couldn't
hurt.... oh boy was I was wrong. I should have just bought good old
American made ones. These
Chinese "retaining ring pliers" are so flimsy they practically bend
more than the retaining rings. But after fidgeting with them for a
while i was able to test out the retaining ring groove; as seen below.
After This the nozzle
is finally made, which consists of a 1.006 OD X .75" ID aluminum tube
with a .75" graphite insert held in place by compression/high temp
glue; which is then formed into a nozzle with a 45 degree convergent
cone, and a 15 degree divergent cone as seen below.
After that is done the rear bulkhead is constructed, which is just a
thick aluminum disc.
Finally, after the addition of some O-Rings, and some Ammonium
Perchlorate Composite Propellant, this sucker is ready to be test fired.
I will get a video up of the test fire as soon as possible.