START SWITCH ASSEMBLIES.--Two start
PITOT ASSEMBLIES.--Two pitot assemblies
switch assemblies are incorporated into the multi-
incorporating deployable pitot heads (fig. 2-12) are
purpose initiators. During ejection, the start switches
mounted on the main beams behind the parachute
supply a start signal to the sequencer at the correct time
container. Removable covers prevent entrance of
in the sequence.
foreign objects during maintenance.
The pitot heads are maintained in the stowed
Multipurpose Initiators
position by locking mechanisms that are released
during seat ejection, as the seat separates from the
Two initiators multipurpose (IMP) (fig. 2-14) are
catapult by gas pressure from the multipurpose initiator
attached to the lower outer faces of the seat main
cartridges (fig. 2-13). When deployed, the pitot head
beams. During the ejection sequence, the IMPs supply
assemblies supply dynamic pressure inputs to the
gas pressure to operate the barostatic release unit delay
electronic sequencer.
mechanism, the underseat rocket motor, the pitot
deployment mechanisms, and the internally mounted
When the pitot assembly is installed on the seat
start switch assemblies.
beam, the inboard static pressure connector connects to
a void in the seat beam. The sequencer is installed on
Each IMP comprises a body, machined and drilled
the forward face of both pitot assemblies and connects
to accept a start switch, a static lanyard assembly, a
to the dynamic and forward static pressure connectors.
spring-loaded firing pin, and an impulse cartridge. A
IMPULSE CARTRIDGE
GAS OUTLET TO BAROSTATIC
RELEASE UNIT, PITOT MECHANISMS
AND UNDERSEAT ROCKET MOTOR
ELECTRICAL
CONNECTOR
FIRING PIN
SHEAR PIN
DIAPHRAGM
FIRING PIN
SPRING
DISCONNECT
DEVICE
COILED
LANYARD
START SWITCH
ELECTRICAL
WIRING
START SWITCH
PLUNGER
LOWER DROGUE BRIDLE
STATIC LANYARD
RELEASE UNIT PISTON
LOWER END FITTING
Figure 2-14.--Multipurpose initiator, left hand.
2-13
