Article: Pressure-Parachute

  • EjectionSeat-640x250
    November, 1950, Canadian Aviation
    by Ronald A. Keith

    When the writer visited England in the fall of 1946, we were frustrated in our efforts to fly in a jet fighter. There were only two dual-control Meteors in England at the time. When we tracked these down, with high hopes of a flip in one of them, it was to discover that they were both occupied with the development of the Martin-Baker ejection seat. It is some compensation now to realize that the project that crowded us out of the Meteor flight has met with great success.

    Actually, Martin-Baker has been engaged since 1944 in intensive research and design on the problem of catapulting the pilot safely out of high-speed, high-flying aircraft. The ejection seat is now standard for all RAF fighters and bombers.

    We now receive word of the latest development, an ejection seat with a parachute that opens automatically. The problem has been that if the pilot opened his parachute at great height he would suffer from cold and anoxia during the slow decent. On the other hand, if he delayed the opening, he might lose consciousness and fail to pull the ripcord. If he is wounded, the difficulties are increased.

    A large number of different schemes for automatic operation were considered. In earlier schemes, a mechanism was designed for releasing the airman’s seat harness and causing him to fall away from the seat. This would cause the parachute ripcord to be pulled and the parachute would then develop in the normal way. However, the fatal objection to this otherwise simple arrangement is that the seat might overtake his parachute and cause an accident.

    The final design of the Martin-Baker Automatic Ejector Seat enables pilots and aircrew to escape from the high-speed aircraft at all altitudes. It is effective at any speed and under any “G” acceleration that may occur whatever the altitude of the aircraft. Nevertheless, by the simple movement of a hand lever the airman has his parachute available for normal ripcord operation either without ejection, with the seat, or at any time after ejection has taken place.

    After jettisoning his canopy, the airman withdraws his feet on to the ejection footrests and pulls the firing handle above his head with both hands, thereby withdrawing a flexible face screen and ejecting himself in the seat from the aircraft. The footrests are spring-loaded and remain at floor level whatever the position of the adjustable seat pan.

    A static line next fires the drogue gun on the seat which withdraws from the top of the pack the small drogue parachute attached to the top of the seat by a shackle and thus retards and stabilizes the seat. A timing device, set in motion as the seat is ejected, releases the drogue shackle after a delay of four seconds provided the seat is below 10,000 feet altitude.

    If the seat has been ejected above this altitude, a barostat overrides the timing device until the seat with the occupant has fallen to this present height. Release of the drogue shackle frees the drogue from the seat and at the same time releases the harness locks, which attach the airman and his parachute to the seat. The drogue withdraws the airman’s parachute from the pack and the seat falls away below him while his parachute develops in the normal manner.

    If the airman wishes to attempt a non-ejected escape from the aircraft, assuming such to be possible, he pulls the manual override lever, thereby releasing his seat harness and parachute pack from the seat and, once free from the aircraft, operates his parachute by the manual ripcord.

    A seat-type dinghy pack is normally fitted which contains the inflatable rubber boat and survival equipment.

    85-49-004

    M-B Ejection Seat
    This article originally appeared in the November, 1950 edition of Canadian Aviation magazine.

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