are several types of rocket motors used in the hobby. Historically
speaking, the ancient Chinese's were among the first to use
firework-type propellants. Later, much of this technology
developed by the Chinese was borrowed by other groups.
the most common hobby rocket motors, or engines
as they are some times called, are made of compressed black
powder. In both mid-power and high-power rocketry most of
the motors flown are composite-based typically made from ammonium
perchlorate (AP). These AP motors typically provide three
times the power of a typical black powder motor of the same
to black powder and composite rocket motors, there are several
manufacturers who are selling hybrid rocket motors. Hybrid
motors use inert materials which when combined with nitrous
oxide as an oxidizer create a very powerful rocket motor.
These inert materials may include card board, paper and plastic.
The hobby of model rocketry began with what are now called
single use motors. Some companies call these rocket
engines. These motors were commonly manufactured
using hydraulically compressed black powder which was contained
in paper tubes.
the 1960's, Irv Wait founded his Rocket Development Company
and created the first composite model rocket motors called
"EnerJets". EnerJets were later bought and sold
by Centuri until 1974 when the company shut down the production
line because of low profit margins.
and 1979 two companies reintroduced composite model rocket
motors. These companies were Small Systems Sounding Rockets
or SSRS (later known as Crown Rocket Technology) and Composite
Dynamics. SSRS chose 1.125" diameter paper phenolic motor
casings with machined graphite nozzles. The other company,
Composite Dynamics, used filament-wound fiberglass motor casings
and cast ceramic nozzles for their motors. Both companies
chose HTPB (hydroxyl-terminated polybutadiene) fuel binder
which was a first in hobby rocket motors.
Dynamics also developed its first motor to be called the E20.
This motor had the same physical dimensions as an Estes D-12,
however, the E20 produced almost three times as much power
manufacturers have continued to develop the composite rocket
motor. New technologies include reloadable motor technologies
which allowed the customer to use metal hardware cases over
and over again by purchasing reloadable motor kits containing
the propellant for each flight.
Like the name implies, a single use motor is designed to be
flown once and disposed of. Typically these motors use a wound
paper or plastic cases in smaller motors and are made of plastic,
phenolic or even aluminum cased in larger motors.
use high power motors usually cost quite a bit more per flight
than the a reloadable motor kit used in a reloadable motor.
Most people in high power rocketry prefer to fly reloadable
A reloadable motor is a motor designed to be used repeatedly
by loading new motor parts into metal hardware casings. A
reloadable motor can be broken down into three main individual
components: an aluminum tube, forward closure and aft closure.
The purpose of each closure is to hold the nozzle on one end
and to seal the other end. In many motors the aft closure
also holds a delay element and black powder charge used in
recovery of the rocket. Motor cases come in different diameters
and lengths to allow for various reload kits of different
size and total energy.
smaller rocket motors which rely on an engine hook
in the rocket to keep the rocket motor in place, in reloadable
rocket motors, the aft closure is usually slightly wider than
the diameter of the case. When the motor is inserted into
the motor mount tube the wider lip keeps the motor from sliding
up through the motor mount tube while the rocket is under
motor kit consists of one or more propellant grains, o-rings,
a nozzle and various other items which are replaced after
each flight. Some manufacturers like Kosdon TRM products use
a graphite nozzle which can be used for up to 20 times before
being replaced. In contrast, AeroTech motors use a different
nozzle which is replaced after every flight.