'Frangible' cockpits

Discussion in 'Modern' started by Graeme, Nov 27, 2007.

  1. Graeme

    Graeme Well-Known Member

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    The Sea Vixen had a crew of two, pilot and observer. The observer was positioned in an enclosed area on the starboard side of the fuselage-known as the ‘coal-hole.’
    Above him was an entry hatch with a small window.

    [​IMG]


    Both crew members were supplied with a Martin Baker Mk 4 ejection seat. In an emergency, the normal sequence was (for the observer) to pull the protective screen down in front of his face, and through a safety interlock, cause the hatch to be automatically jettisoned, which in turn allowed the ejection seat to be fired. If the hatch did not depart, the seat could not be fired.

    I’ve been reading about the exploits of Allan Tarver (pilot) and John Stutchbury (observer) in a Sea Vixen flying over the port of Beira on the 10th of May 1966.

    John Stutchbury Allan Tarver
    [​IMG]


    A long story, but John Stutchbury lost his life as a result of the safety interlock failing. He manually jettisoned the hatch but could not fire the ejection seat. Tarver inverted the Vixen (twice!-with both engines out) hoping Stutchbury could bail out manually.

    It all went wrong.

    The court of enquiry concluded that it was the hatch jettison system that was at fault, not the ejection seat. All Sea Vixens were modified to include a frangible fibreglass hatch over the observer’s cockpit so that from then on, when fired, the ejection seat went straight through it.

    A long intro to a question, but do modern ejection seats ‘punch’ through frangible canopies or does the canopy depart first?

    [​IMG]
     
  2. HoHun

    HoHun Active Member

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    Hi Graeme,

    Normally, either the canopy is jettisoned, or explosive ribbons break the perspex to allow easy exit.

    However, if that fails, the seat can punch through the intact canopy by means of its specially designed superstructure to allow a relatively safe egress.

    Interestingly, the Royal Navy was one of the driving forces behind this as they lost a couple of pilots who died while trying to egress under water after going off the carrier. (The canopy would be firmly held in place by the water pressure ...)

    "Up in Harm's Way" by Mike Crosley has a bit of information on the history of that. A really great book, by the way!

    Regards,

    Henning (HoHun)
     
  3. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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  4. Graeme

    Graeme Well-Known Member

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    Thanks Joe, interesting site!

    Thanks HoHun. I've read that a Lt B D Macfarlane was the first pilot to eject under water in 1954. He was flying a Westland Wyvern (VZ783) and experienced a flame out after a high g catapult launch. His Wyvern fell into the sea and was cut in half by the bow of HMS Albion but managed to eject under water safely in his Martin Baker Mk 1B seat.
     
  5. Blaydon

    Blaydon Member

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    This feature for underwater ejection was still present up to the Mk 6 seats of the Buccaneer.
     
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