The ejection sequence is initiated by pulling upward on the ejection control handle, which is located on the front panel of the seat bucket. Pulling the ejection control handle requires a force of 15 to 25 pounds through a distance of less than 4 inches. Pulling the control handle fires two M99 ejection initiators, which release hot, high-pressure gas to the ballistic signal transmission system (BSTS). Figure 6-32 is a schematic of the BSTS. The right M99 ejection initiator supplies gas pressure to the right side of the catapult cartridge igniter and the inertia reel gas-generating initiator. The left M99 ejection initiator supplies gas pressure to the left side of the catapult cartridge igniter, thereby

Figure 6-32.- SJU-8/ A ballistic signal transmission system.

providing redundant ignition to the catapult cartridge. As the seat catapult fires, the gas pres-sure forces locking pistons in the catapult tubes to disengage the locking balls, which unlock the inner -and outer catapult tubes. As the seat and outer catapult tubes move upward, the pilot's legs are drawn against the front of the seat by the leg restraint mechanism. Simultaneously, the quick-disconnect fittings for pilot services are separated, and a lanyard on the catapult manifold activates the emergency oxygen bottle, IFF, and AN/ URT-33 emergency radio beacon.

After approximately 16 inches of seat travel, gas pressure is applied to the drogue gun pistons housed in the catapult tubes. These pistons forcibly expel the drogue para-chute container for quick drogue parachute deployment. The drogue parachute provides seat stability and aids in withdrawing the main parachute.

After approximately 31 inches of seat travel, gas pressure is ported to a thruster (pin puller), a 3-second time-delay initiator, a multiple time-delay (0.1-and 1.3-seconds) initiator, and the igniters of the two seat-back rocket (SBR) motors. The SBRs produce the thrust necessary for the seat and pilot to attain sufficient terrain and aircraft tail clearance to permit parachute deployment. The necessary thrust is available even at zero airspeed and zero altitude.

Upon ejection, the seat is stabilized by a Directional Automatic Realignment of Trajectory (DART) system. Two lanyards, attached to the aircraft and feeding through tension brake assemblies beneath the seat, counteract excessive pitch and roll.

The post-ejection sequencing system for deploying the Wind Oriented Rocket Deployment (WORD) motor and drogue release mechanism follows one of four automatic ejection modes, depending on the aircraft's airspeed and altitude. These modes of operation will be discussed later in this chapter. Depending on the mode of operation, the time-delay initiators fire, directing gas pressure to actuate the WORD motor and drogue release mechanism, and arm the aneroid-actuated initiator.

Upon actuation, the WORD motor/ drogue release disconnects the WORD rocket motor. This allows the wind resistance on the drogue chute to withdraw the WORD motor from the seat. When the WORD rocket motor arming cable is withdrawn, it releases the firing pin and ignites the rocket. Depend-ing on the mode of operation, the aneroid-actuated initiator fires. This activates the personnel parachute container opener, releas-ing the personnel parachute. The parachute will be withdrawn by either the WORD rocket motor, drogue parachute, or internal pilot chute.

When the personnel parachute suspension lines and risers become taut, a firing lanyard attached to a ballistic spreading gun extracts the spreading gun firing pin sear. The re-leased firing pin strikes and activates a spread-ing-gun ballistic charge, which expels metal slugs in a 360-degree pattern. The slugs, attached to parachute suspension lines, rapidly inflate the canopy during very low-speed ejection. During high-speed ejection, the air-stream energy far exceeds that of the spread-ing gun. Therefore, the gun has little effect on parachute inflation time. As wind resistance acts on the personnel parachute, tension on the seat and man release lanyards actuates the seat and man separation initiator to produce gas pressure directed to the guillotine. The guillotine severs both inertia reel straps and releases the pilot's upper torso. Simultaneous actuation of seat and man separa-tion mechanical linkage by the lanyards releases the survival kit assembly and pilot from the ejection seat.

The pilot may release the survival package in the survival kit by pulling a handle located near his right hip. After the package drops 12 feet, a snubbing lanyard initiates inflation of the life raft. The remainder of the survival package drops an additional 13 feet and hangs below the life raft to stabilize it during descent.