C I R R U S
C O M P O N E N T M A I N T E N A N C E M A N U A L - C A P S
M O D E L S R 2 0
95-01-01
Page 7
Serials 1005 thru 1267 after SB2X-95-20, 1268 thru
1422 after SB2X-95-17, 1423 & subs w/o Perspective
after SB2X-95-18, 2228 & subs
EFFECTIVITY:
C. Rocket Assembly - Serials 1005 thru 1267 after SB2X-95-20, 1268 thru 1422 after SB2X-95-17,
1423 & subs w/o Perspective after SB2X-95-18, 2228 & subs
The rocket assembly consists of the igniter switch, rocket igniter, and rocket motor. The igniter switch
consists of a steel spring, a plunger, and two electrical contacts to which the activation cable is
attached. A wiring harness connects the switch to an igniter installed at the top of the rocket which via
electrical circuit ignites a booster. In its normal position the firing pin actuator and plunger are inter-
locked with two ball bearings held in place by the inner wall of the igniter body.
(1)
Igniter Switch
Pulling the activation cable compresses the igniter switch spring and cocks the plunger. One
half-inch of plunger travel is required to release the ball bearings and allow the plunger to com-
plete an electrical circuit between the contacts.
(2)
Rocket Igniter
The electrical circuit heats the high-resistant wire, igniting a black powder and magnesium pri-
mary booster in the end of the igniter. The igniter is unarmed in its normal configuration since the
spring is un-compressed and the plunger is separated from the contacts by a 0.060-inch gap.
(3)
Rocket Motor
The rocket motor uses stored chemical energy in the form of a solid propellant to provide the
thrust forces necessary to rapidly remove the enclosure cover and extract the parachute from its
enclosure.
The rocket motor components consist of the motor case, motor aft bulkhead, propellant, and
rocket nozzle. The motor case/aft bulkhead contains the propellant and serves as a pressure
chamber when the propellant is burning.
The rocket motor uses a composite propellant, consisting of a heterogeneous mixture of ammo-
nium perchlorate (AP) and aluminum powder (Al), the oxidizer and fuel. These are the most
commonly used ingredients in modern solid propellants.
The rocket motor nozzle provides for the expansion and supersonic acceleration of the hot
gases. The rocket motor has been designed to specifically meet the extraction requirements of
the parachute.
4 May 2015
