Overview
The Mk. 2 automatic seats were successful in providing safe escape from the aircraft in service at the period, but there was still room for improvement at very low altitudes and very high speeds. In addition, the advent of aircraft such as the Javelin and the V bombers with their high fin projections and higher operating speeds, made it necessary to increase the height of the ejection trajectory, any increase also improving the chance of a successful ejection at low altitudes.
Specifications
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Specifications
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Mk 3 (Typical)
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Operating ceiling
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40000+ ft
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Minimum height/speed
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Unknown
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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
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Maximum Speed for ejection
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400+ 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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Separate parachute, seat harness
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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 or four
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secondary cartridges, 72 in. stroke
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Ejection initiation
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Face screen and seat pan firing
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Barostatic time-release unit
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Yes, tripped during ejection sequence
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Manual override handle
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No, but provision for manual separation
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Timers
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Time-release unit for man/seat separation
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Seat adjustment
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Up/down
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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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Liferaft pack
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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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Option, aircraft variant dependent
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How it works
Face screen seat firing handle pulled
Canopy jettison initiated (if fitted)
Ejection gun fires, seat moves up guide rails
Emergency oxygen tripped
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
Below 10000 ft
1.5 sec (3 sec on earlier Mk3) 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
Drogues deploy main parachute, aircrew separates from seat
Normal descent
In the event of failure of time-release unit
- aircrew pulls D ring on parachute harness. This pulls slide disconnect pin
which disconnects withdrawal line from parachute
- pulling D ring also removes canvas flap from second D ring
- aircrew pulls second D ring to operate parachute
Variants
Information to be posted shortly