Introduction of the rocket pack to the range of Mk. 4 and Mk. 5 seats created the basic Mk. 6 and Mk. 7 ranges respectively. However, many of the Mk. 7 range of seats were subsequently embodied with additional improvements in design such as Power Retraction Systems, Remote Fired Rocket Systems and Sequencing Systems as later described. The Mk. 8 seat (developed for the T.S.R.2 aircraft), was a rocket assisted seat and was undoubtedly the most advanced aircrew escape system produced up to that time. Despite the unfortunate cancellation of the T.S.R.2, much valuable experience was gained, which was fully exploited in later designs.

Specifications

How it works

Face screen or seat pan mounted seat 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 operate
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
Underseat rocket pack initiated
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
        1.5 sec (3 sec on earlier Mk 4, 1.25 sec on later Mk 4) 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