BRS-6 General Installation Guide - CAFE Foundation

Once ignited, the grains will burn on all exposed surfaces to form hot gases that are exhausted
through the nozzle. The propellant's performance is a function of its burning rate and the
burning surface area of the grain. The geometry of the grain is therefore critical to achieving
the desired thrust profile. Our rocket motors use grains with a cylindrical bores through their
centers, or internal burning grains, to achieve the desired burn surface area.
The rocket motor nozzle provides for the expansion and supersonic acceleration of the hot
gases. The rocket motor's performance is a function of the propellant performance and the
nozzle design and can be defined by its thrust versus time curve and the total impulse, It ,
which is the thrust force, F (which can vary with time) integrated over the burning time, t.
Each BRS rocket motor has been designed with a thrust-time curve and total impulse that
specifically meet the extraction requirements of the particular parachute.
Solid fuel motors have a flame, but this is not the problem some imagine for two reasons; one
simple, one more complex. With an extremely high departure velocity in the first tenth of a
second, the flame is gone before it can cause problems. The more complex explanation
involves a pressure front set up by the ignited fuel. The main content of the rocket’s exhaust is
water vapor and non-flammable gases. These expand so rapidly that they will literally push
away fuel fumes before they can get warm enough to ignite.
BRS currently certifies its solid-fuel rockets for twelve (12) years of service life. At the time of
expiration, the old rocket must be properly disposed of and replaced with a new one. However,
this means that a rocket shipped from BRS to a customer need never be returned to the factory
for service, eliminating any owner difficulty in shipping hazardous goods.
4. The Activation Assembly
The rocket motor is activated by pulling a red activation handle mounted securely within reach
of the pilot/passenger. This handle is connected to the rocket motor igniter with a flexible,
stainless steel aircraft grade cable routed through a Teflon-lined housing. The handle is usually
the only part of the system accessible to the pilot in flight.
Figure 6: BRS Activation Handle/Holder
Two separate and deliberate pilot actions are required to deploy BRS parachutes. The first
action requires that the pilot remove the safety pin from the activation handle holder during
the pre-flight inspection. The second action requires the pilot to pull the activation handle
several inches out of the holder. The first few inches of motion take up cable slack that has
been intentionally built into the system to prevent inadvertent activation due to flexing of the
BRS-6 General Installation Guide (Models 600 through 1800) Page 13 of 47
BRS Document № 020001-03 Revision D Copyright © 2008, BRS Inc.