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Old 28th May 2006, 12:33
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Centaurus
 
Join Date: Jun 2000
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Milt will recall this better than me but in around 1951 the RAAF lost three Vampire Mk 30 aircraft (Rolls Royce Nene's instead of Goblins). In each case the aircraft were in normal high altitude dives (from aerobatics and the other from practice quarter attacks) when the pilots reported getting into compressibility. I suppose severe case of Mach tuck is today's description.
They were unable to recover from these dives and with no ejection seats in those aircraft the pilots were killed. The problem was the installation of two additional engine air intakes that were installed on top of the engine behind the pilots canopy. Shock waves formed above these intakes (called Elephant Ears) at high speed - 0.73 or thereabouts I believe - and these caused reduced elevator effectiveness. At 10,000 ft in their dives the aircraft were vertical leaving insufficient room to recover. The fix was to relocate the intakes under the engine and the Vampire would recover unassisted after that.
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