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Aviation History
1950
1950 - 1010.PDF
644 FLIGHT DROPPING THE PILOT ... himself manually from the falling seat, stepping out into space, and then manually operating his back parachute. The automatic devices, in fact, have not yet reached the foolproof stage. Some trouble was also encountered at first with the standard type of helmet and oxygen ma.«Jr _ loss of the helmet-mask combination occurring in several of the tests at some time during the ejection. The helmet was modified by the addition of a reinforced Plexiglas visor that spring- locked in the down position and covered the open part of the face between the helmet and oxygen mask, the visor being contoured to mate with the mask, while the air space between visor and mask was sealed off with a rubber flap. This combination remained in place with no tendency to blow off at the highest speed tested, viz., a true air speed of 550 m.p.h. The sequence of operation of the safety-belt and para- chute equipment during an ejection test is shown by the seven phases depicted in Fig. 2. Phases 1-3 are the initial'' stages of the ejection and consume approximately 0.4 sec from the instant of seat firing. Phase 4 shows the seat and man as they appear approximately 4 sec after seat firing. Phase 5 shows the instant at which the disconnect device frees the stabilizer parachute, allowing it to actuate the automatic lap-belt. Phase 6 shows partial deploy- ment of the retarder parachute and the personnel-parachute static line. At phase 7 the personnel-parachute rip cord 40 TO 0 \ \ \ \ v v f s ****** * •^ J /f 100 200 300 400 500 INDICATED AIR SPEED (m.p.h) 600 R(. 3. Lockheed TF-80C ejection tests : Tail clearance t. speed. has been withdrawn by the 20ft static line and both personnel and retarder parachutes are fully inflated. Altogether, some forty TF-80C flight tests were con- ducted with human and dummy subjects. The five human tests were performed by Air Force volunteer personnel flying from Hamilton Air Force Base on San Pablo Bay, near San Francisco, where there was a suitable area for parachute descent into water. This was considered desir- able in order to minimim the chance of injury in landing; also, any injuries that might be sustained could be attributed to the ejection procedure. Recovery of the subjects was also facilitated, being effected by high-speed crash boat within 30 sec. In each of the five live drops the subjects were ejected at around 10,000ft, the I.A.S. being successively stepped up from 340 to 470 m.p.h., with corresponding T.A.S. of 400-550 m.p.h. Actually, one of the dummy tests reached a T.A.S. of 580 m.p.h., while three of the dummies were fired overboard between the 26,000 and 30,000ft level. Although a number of minor malfunctions occurred in various items of equipment, these tests showed that the wind-blast pressures, deceleration forces and parachute opening shocks were insufficient to cause personal injury up to the speeds tested; moreover, it was unequivocally stressed by the test subjects that baling-out by the catapult technique produced nothing like the shock of the ordinary jump method. These tests confirmed that a 300-lb test- subject, comprising pilot, seat and gear, could be satis- factorily ejected, with adequate tail clearance, up to I.A.S. of approximately. 500 m.p.h., as shown in Fig. 3. Taking a final look at Fig. 3, one is tempted to speculate on the compressibility characteristics of genus homo should some enterprising (or unfortunate) specimen fire himself r Fig. 4. Douglas Skyknight gravity chut* and ditching hatch. A - Ditching hatch, opm. . ' A" ™ Ditching hatch, dotad. • - " Vaulting bar." C = Cabin ascapa door, open. D =• H/draulkaHy oparatad door, formswindbraak. E = Fly-away door. . ' f — Saat-badu detach and twing iata> cornari. G — Saat-aam slid* ovtward and aft. overboard at an indicated air speed of 500 m.p.h. at, say, 40,000ft—which is roughly equivalent to a true speed of 1,000 m.p.h. and a Mach Number of 1.5. It would be interesting to know whether the long, thin pilot stands a better chance—or less bruising from shock waves—than the short, tubby chap when pitched over the Mach moun- tain. In due time, no doubt, genus homo of the rocket age will assume the appropriate Darwinian mantle to take care of this problem. Douglas Gravity Chute—Like other jet aircraft manu- facturers. Douglas are well experienced in the design of emergency escape systems, possibly more so than most by reason of their high-speed research programme for both the Air Force and the Navy. Douglas have done consider- able design and development work with the Martin-Baker type of seat, even to the point of incorporating in the Navy AD Skyraider the face-protection blind which, we seem to recall, was one of the distinctive features of the original Martin-Baker design. Lockheed, on the other hand, working in conjunction with the Air Force, have apparently discarded the pull-down blind in favour of a visored helmet, since the tests noted above were quite definite in showing no facial discomfort up to the speeds tested. In the case of the Douglas F3D Skyknight twin-jet, two- seater, all-weather naval fighter, wherein the pilot and radar operator sit side by side, it was decided to employ an inclined gravity slide-chute or tunnel for exit through a ventral escape hatch, as shown in Fig. 4. Entrance to the chute is through a door located between the seats immediately aft of the cockpit, while the exit hatch is between the twin jet units. The door of the exit hatch comprises forward and after panels, the forward one being hydraulically operated to project outward into the air- stream to form a wind-break, while the rear portion is jettisoned. Douglas believe that this scheme is lighter in weight than an ejector seat.
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