To suit the special requirements of the United States Navy, the Mk. 5 seat was introduced in 1957 and its production paralleled to that of the Mk. 4. In general the Mk. 5 seats conformed to the same basic pattern of the Mk. 4 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 Mk. 5 seats the American system of jettisoning the canopy was linked up with the face blind firing handle. The low level capabilities of the Mk. 5 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 Mk. 5 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 Mk. 5 seats was made, replacing the original American ejection seats fitted in these aircraft, because the Norwegian Air Force preferred Martin-Baker seats. Altogether the Mk. 5 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.
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Specifications
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Mk 5 (Typical)
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Operating ceiling
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50000+ ft
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Minimum height/speed
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Zero/90 KIAS
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Crew boarding mass range
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70.4 to 101.7 kg
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Crew size range
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5th to 95th percentile Maximum
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Maximum Speed for ejection
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600+ KIAS
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Parachute type
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Irvin I 24
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Parachute deployment
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Drogue assisted
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Drogue parachute type
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Duplex drogues 22 in. and 5 ft
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Drogue deployment
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Drogue gun. Cartidge generated gas. Initiated by
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0.5 sec clockwork time-delay, tripped during
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ejection sequence
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Harness type
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Combined
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Ejection seat operation type
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Ejection gun
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Ejection gun
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80 ft/sec One primary cartridge, two secondary
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cartridges, 72 in. stroke
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Ejection initiation
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Face screen or seat pan firing
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Barostatic time-release unit
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Yes, tripped during ejection sequence,
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g-restrictor, time-release unit for man/seat
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separation
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Manual override handle
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Yes
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Guillotine
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Yes
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Seat adjustment
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Up/down, manual operation
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Arm restraints
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No
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Leg restraints
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Yes, two garters
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Oxygen supply
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Bottled oxygen
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Personal survival pack
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Yes with liferaft
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Aircrew services
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Personal equipment connector (PEC) provides
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connections for
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- main oxygen
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- emergency oxygen
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- air ventilated suit
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- anti-g suit
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- mic/tel
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Canopy jettison
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Yes, aircraft variant dependent
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How it works
Face screen seat or seat pan firing handle pulled
Canopy jettison initiated
Ejection gun fires, seat moves up guide rails, secondary cartridges fire
Emergency oxygen tripped
Aircrew services disconnect
Leg restraints disconnect
As seat rises, static line initiates time-delay which fires drogue gun after 0.5 sec
As seat rises, static line initiates time-release unit
22 in. dia then 5 ft dia drogues stabilise and slow seat
Above 10000 ft
- Barostat prevents operation of time-release mechanism
High speed
- g-restrictor prevents operation of time-release mechanism
Below 10000 ft, 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, aircrew separates from 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. Aircrew can then use rip cord to operate parachute