The Ejection Site

Apex The top, usually the center, of an arc such as a ballistic trajectory or a parachute canopy.
Bridle A section of connecting line between a drogue or main parachute and the attachment point on the harness or seat.
(Seat) Bucket The lower portion of the seat which normally contains the survival kit. In monoqueue construction seats this is an integral portion of the seat. In other seats such as early USAF and USN seats and Martin-Baker seats the bucket are separate portions attached to the rest of the seat.
Canopy The cover over a cockpit. This term can refer to a transparancy, or a framework containing a transparency.
(Parachute) Canopy the dome like fabric portion of the parachute assembly.
Canopy Capsule A capsule design where the pilot’s seat rotated up into the canopy and the entire unit was jettisoned from the aircraft.
Catapult Normally a ballistic cartridge to begin seat motion. In the earlier seats, this was the only source of thrust for seat movement.
Catapult Gun The device which contains the catapult cartridge. Usually a tubular structure running vertically in the rear of the seat. Martin-Baker catapults usually have one main cartridge and two or four secondary cartridges to continue seat motion. The Martin-Baker catapult gun has three telescoping tubes and also mount the seat rails which guide the seat out of the aircraft.
Crew Escape Module A section of an aircraft which is explosively separated and rocketed to a safe recovery situation. Includes at minimum the cockpit area.
DART a set of nylon ropes and braking systems attached to the underside of some ejection seats to control the seat deployment in a stable fashion.
Drogue parachute A small parachute designed to be deployed from a portion of an egress system to slow and stabilize that portion. Drogues can be used to slow a seat/man package, a crew escape module, a nose or canopy capsule, or an airman.
Duplex Drogue A pair of drogue parachutes deployed in sequence to lessen the shock on the system from a single large drogue opening at speed. The smaller drogue deploys and its lines are attached to the larger drogue at the canopy apex. This pulls the second canopy out when the forces are high enough.
Envelope Usually refers to a graph of the airspeed and altitude of safe operation of a system. The area within the chart is the safe zone, and the area ‘outside the envelope’ is the dangerous area. When testing a system to verify the safe expansion of the envelop to a new area it is refered to as ‘pushing the envelope’.
(Ejection) Capsule a seat with a protective outer cover capable of closing over one or more aircrew and providing a protected environment during emergency egress from an aircraft.
Ejection Sequence a series of events that occur during the functioning of an egress system which should lead to a successful recovery of the aircrew.
Egress System The entire system containing not only the seat, but also the canopy or hatch jettisoning mechanisms, and the emergency life support equipment. Includes the aircrew personal equipment Some types include: ejection seat and canopy, ejection seat through canopy, crew escape module, ejection capsule and hatch, extraction rocket, and other forms of capsules including nose and canopy capsules
Electronic Sequencer A device designed to control an egress system by controlling the timing of events based on a selection of modes by the same device. The ACES II uses an analog device for this and the NACES and later Martin-Baker Aircraft seats use a digital computer.
Extraction Rocket A type of egress system where a rocket is connected to the personal parachute via a lanyard. The rocket is fired out of the aircraft and via the lanyard it extracts the aircrew from the aircraft and then extracts the parachute from the pack. Also called a Tractor Rocket.
Guide Rails A structure which acts as the interface between the seat and the aircraft. They guide the seat on its movement in the aircraft. Many seats use a set of rails which interface with the seat via a set of rollers on the back edges of the sides. Many Martin-Baker seats use a catapult with rails mounted on the edges of it which interface with small metal tabs called slippers on the instide of the main beam assembly.
(Parachute) Harness The portion of a parachute system which is worn directly on the person. This may include a quick disconnect for the risers. It also may contain a survival kit or attachments for one. In some cases a Personal Lowering Device (PLD) may be attached as well.
Koch/Frost Fittings Quick disconnect fittings made by the H.R. Koch and Sons company. These fittings replaced the Rocketjet and Capewell fittings on earlier parachute systems. The Frost-type are used by the USAF on the F-16 ACES II, and by NASA for most of their seats. The Koch fittings come in either USAF or USN varieties. The USAF variety has the male portion of the connector on the risers, and the USN version has the male on the torso harness. The female fittings are slightly different in design as the airman's fingers will access them in opposite directions.
Nose capsule A system where the entire nose of the aircraft from just aft of the crew seat is severed from the aircraft. In some cases the aircrew would have the ability to bail-out from this, in others, the entire unit is lowered to the ground.
Seat Separation the point where the aircrewman is released from the seat.
Survival kit a collection of materials for the air crew to use after egress from the aircraft to assist in survival and recovery.
Shroud Lines The string like connections between the parachute canopy and the risers. Are attached to the perimeter (or hem) of the canopy.
Personal Recovery Parachute The primary parachute designed to lower a single airman to the ground safely.
Personal Lowering Device (PLD) A device which is attached to the gear a crewman will end up with after seat separation designed to allow the crewman to decend from trees or other similar snags. Attaches to the harness or risers and allows for a controlled decent by means of a nylon rope which is part of the PLD.
Primary Recovery Parachute The main parachute for an egress system designed to lower an aircrew, a module or a capsule to the ground.
(Parachute) Riser(s) The section of the parachute assembly which connects the harness to the shroud lines.
Rigid Seat Survival Kit (RSSK) a container which contains the survival kit, and usually doubles as the seat section of the seat bucket.
Rocket Catapult (ROCAT) a tubular device which combines a ballistic catapult cartridge to begin seat motion, and a rocket unit which is ignited near the end of the catapult stroke and provides thrust to continue the sear motion.
Tractor Rocket See Extraction Rocket
Underseat rocket One form of additional propulsion for an ejection seat. Usually used in Martin-Baker seats.

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