MK5 EJECTION
SEATS
Introduced into service in 1957 First Mk5 ejection was on 25th September 1958

To suit the special requirements of the United States Navy, the Mk5 seat was introduced in 1957 and its production paralleled to that of the Mk4. In general the Mk5 seats conformed to the same basic pattern of the Mk4 and included the standard 80 feet per second gun, 1¼ second time delay with g switch and barostatic control, duplex drogue system plus all the other features necessary for their use at all speeds and heights. To meet specific American crash requirements however, the seat structure and harness were strengthened to withstand deceleration loads of 40g, instead of the 25 g British specification, resulting in a slight increase in weight.

In addition, the seats were provided with special canopy breaker peaks on the headbox to provide for the eventuality of having to eject through the canopy, standard practice on the A.5 seat installed in the Grumman 9F-8T Cougar. On the majority of the other Mk5 seats the American system of jettisoning the canopy was linked up with the face blind firing handle. The low level capabilities of the Mk5 seat were successfully demonstrated in August 1957, when Flying Officer Sidney Hughes ejected from a Grumman Cougar at the U.S. Naval Air Test Centre, Patuxent River, before a group of high ranking U.S. Navy Officers. Subsequently, the decision was made to standardise the Martin-Baker Mk5 seats for all United States Navy jet fighters and trainers, and many fuselages were sent to the Company’s factory at Denham for trial installations.

North American Sabre and Republic Thunderflash aircraft of the Norwegian Air Force were the first of many N.A.T.O. aircraft to be flown into Chalgrove Airfield where the installation of Martin-Baker Mk5 seats was made, replacing the original American ejection seats fitted in these aircraft, because the Norwegian Air Force preferred Martin-Baker seats. Altogether the Mk5 seat has been fitted to nearly twenty types of American aircraft, including such advanced aircraft as the McDonnell Phantom, L.T.V. Crusader, and Grumman Intruder.

Operating Ceiling 50000+ ft (15,250m)
Minimum height/Speed Zero/90 KIAS
Crew boarding mass range 70.4 to 101.7kg
Crew size range 5th to 95th percentile
Maximum Speed for ejection 600+ KIAS
Parachute type Irvin I 24
Parachute deployment Drogue assisted
Drogue parachute type Duplex drogues 22in. and 5ft
Drogue deployment Drogue gun. Cartridge generated gas. Initiated by 0.5 sec clockwork time-delay, tripped during ejection sequence
Harness type Combined
Ejection seat operation type Ejection gun
Ejection gun 80 ft/sec One primary cartridge, two secondary cartridges, 72 in. stroke
Ejection initiation Face screen or seat pan firing
Barostatic time-release unit Yes, tripped during ejection sequence, g-restrictor, time-release unit for man/seat
Manual override handle Yes
Guillotine Yes
Seat adjustment Up/down, manual operation
Arm restraints No
Leg restraints Yes, two garters
Oxygen supply Bottled oxygen
Personal survival pack Yes with liferaft
Aircrew services Personal equipment connector (PEC) provides connections for
- main oxygen
- emergency oxygen
- air ventilated suit
- anti-g suit
- mic/tel
Canopy jettison Yes, aircraft variant dependent
  • Mohawk
  • CF-105
  • Sabre
  • Thunderflash
  • F-8 Crusader
  • T-33
  • Phantom
  • Hawker
  • Cougar Trainer
  • A6 Intruder
  • F3H Demon
  • FJ4 Fury
  • F4D Skyray
  • The pilot pulls the face screen seat firing handle
  • Canopy jettison initiated
  • Ejection gun fires, seat moves up guide rails and the secondary cartridges fire
  • Emergency oxygen tripped
  • Aircrew services disconnect
  • Leg restraints operate
  • As seat rises, static line initiates time-delay which fires drogue gun after 0.5 seconds
  • As seat rises, static line initiates time-release unit
  • 22 in. dia then 5 ft dia drogues stabilise and slow seat

Above 10000ft

  • Barostat prevents operation of time-release mechanism

High speed

  • g-restrictor prevents operation of time-release mechanism

Below 10000ft, (low speed)

  • After initiation of time-release unit, the plunger releases scissor shackle to transfer pull of drogue to lifting lines of parachute, releasing it from seat.
  • Release face blind
  • Harness and leg lines released from seat
  • Drogues deploy main parachute, pilot separates from the seat
  • Normal descent
  • Manual separation system available if necessary. Operation of manual separation handle fires a cartridge that operates a guillotine, severing the parachute attachment line, linkages function releasing parachute harness, negative-g strap, PEC and leg restraint cords.
  • Freeing parachute from seat.
  • Pilot can then use rip cord to operate parachute
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