This
information was provided by Tripoli Rocketry Association, Inc. Please
visit their web site at: www.tripoli.org.
Composite motors are pretty neat. Although not as simple as single use black powder motors, composite motors are quite a bit more powerful and have made high power rocketry a realistic hobby for a lot of us.
Although there are single use composite motors, the majority of composite motors in use are the Aerotech Reloadable Motor System (tm) (RMS) motors. The RMS system consists of a machined aluminum tube (casing or case) capped at one end by a gold anodized rear bulkhead and on the other end by a black anodized forward bulkhead.
The
forward and rear bulkheads are threaded and
screw onto the aluminum tube after the propellant is inserted into
the casing. Various O-rings are used in the assembly to keep the
burning propellant inside of the casing. (Instructions are included
with propellant reloads. Read the instructions and follow them
carefully. Incorrect assembly of the motor WILL result in a cato --
catastrophic failure -- of the motor and damage to your rocket).
The various parts of the motor are covered in a THIN layer of grease before assembly -- for example, the O-rings are greased until "shiny". Aerotech includes a small amount of grease with the casing assemblies. When the supplied grease has been used up you can use other greases such as bicycle chain lube or even KY jelly. Remember -- only a SMALL amount of grease is necessary... just enough to make everything shiny.
Composite motors get their name from the chemicals used to make up the propellant. Fundamentally the propellant is an oxidizer held in a suspension by a binder -- usually a form of rubber. The binding rubber is also the fuel for the propellant. When you build your first RMS motor take a minute and feel the propellant -- it kind of feels like a pencil eraser. The chemical mixture of the composite motor is very similar to the propellant used in the Space Shuttle solid boosters. The sound of a composite motor launching (particularly the larger motors) is more like a ROAR than the whoosh of black powder motors.
Some interesting facts about composite motors...
Blue
Thunder a propellant mixture that gives a loud roar and a
purple
flame when the motor is launched.
White
Lightening a propellant mixture that gives a bright white flame
when
launched.
Black Jack a
propellant mixture that gives off a LOT of blackish smoke
when the
motor is launched.
G64W my first composite motor... a common
29mm motor.
I357T one of my favorite motors, fast burn, lots
of roar!
K550W a powerful motor, 5 foot of trailing flame when
launched.