aircraft-attached 0.3-second delay initiator,
which fires the rocket catapult. On the for:
ward two seats,
an additional 0.5-second
delay MK 11 MOD 0 initiator is in series
with the 0.3-second delay initiator to delay
forward seat ejection sequencing by 0.5 second
after the rear seats eject. The eject mode
selector handles on the pilots and copilots
seat provide pilot or copilot control of individual
or group ejection of crew members.
The first-phase propulsion of the rocket
catapult starts the seat up in the guide rails.
When the seat has moved approximately
two-thirds the length of the guide rails, the
second (or sustainer) phase of the rocket
catapult ignites to provide boost for the
additional height required during ejection.
At sustainer separation, gas pressure from
rocket ignition is used to ignite the seat
stabilization control system, the yaw thruster,
and the seat-attached 0.3-second delay ini-
tiator for harness release. Before the seat
clears the guide rails, the following five
functions occur: crew member services to
the aircraft is disconnected; the parachute
arming lanyard is pulled, which arms the
parachute release actuator; the lanyard con-
nected to the aircraft structure actuates the
emergency oxygen bottle in the survival kit
to supply the crew member with emergency
bailout oxygen; the yaw vane is deployed,
and the quick-disconnect coupling on the
right side of the seat separates.
Following burnout of the yaw thruster
rocket and sustainer rocket, and upon the
completion of the pitch stabilization control
function, the seat-attached 0.3-second delay
initiator fires. Gas pressure from the initi-
ator enters the harness release actuator,
which drives the piston upward to rotate
the bell crank mounted below the actuator
to retract two survival kit retaining pins
and shoulder harness pin from two inertia
reel straps. Retraction of retaining pins frees
the crew member and his survival equipment
from the seat. The base of the clevis on
the lower end of the actuator piston strikes
the firing control disconnect actuating arm.
Movement of the arm retracts a spring-loaded
retaining pin from the firing control dis-
connect assembly, and releases the ejection
control handle cables from the assembly.
A crew member, who may still be holding
one of the ejection control handles, is now
freed from any restraints that would prevent
the final separation from the seat. As the
harness release actuator piston completes the
stroke, the pressure within the actuator is
ported to the man/seat separator rocket,
causing the rocket to ignite.
The thrust of the man/seat separator
rocket simultaneously rotates and propels
the seat away from the crew member with
a differential velocity of up to 25 to 30
feet per second. The probability of collison
between the seat and a crew member or the
parachute after separation is minimized, be-
cause no attempt is made to decelerate the
seat as the seat travels along a divergent
trajectory. As the seat and crew member
move into divergent paths, the parachute
actuator is armed and the external pilot
chute is deployed. After a 0.55-second de-
lay, the main parachute is aerodynamically
deployed. Just before the parachute shroud
lines stretch, the ballistic spreading gun is
fired to forcefully initiate parachute infla-
tion.
If a crew member is above an altitude
of 14,000 (± 500) feet, a preset aneroid in
the parachute actuator delays parachute de-
ployment until the crew member has de-
scended to the correct altitude. The para-
chute actuator delay cartridge then fires,
causing parachute deployment. The crew mem-
ber can select parachute deployment at any
altitude by pulling the manual ripcord on the
parachute.
If the automatic ejection system malfunc-
tions, the crew member can pull the inter-
nal jettison handle/initiator(s) in the crew
compartment to cut the window/hatches away.
Over-the-side bailout is initiated by pulling
the harness release mechanism, which discon-
nects the rigid survival kit and the para-
chute from the seat structure. The crew
member can then stand up and exit the
crew compartment. When clear of the air-
craft, the crew member pulls the parachute
manual ripcord located on the left riser
strap immediately above the parachute can-
opy release fitting. The parachute flaps are
thereby released, and the parachute deploys.
6-3