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Aviation History
1949
1949 - 1787.PDF
FLIGHT, 27 October 1949 Operation of undercarriage and flaps (twin hand pumps will also be fitted as part of this system, to provide a second emergency method of lowering the undercarriage) ; and (4) booster emergency system, with one electrically driven pump, for secondary flying-control boosters only. Failure of any of the four turbojets will not affect main or booster systems, and change-ovei from primary to secondary boosters will be by manual control. A separate accumulator, charged by the standby system pump, supplies pressure to the wheel brakes for parking. All fuel is carried in the wing, the tanks in the centre section being of bag type, and those outboard, integral. The fuel system is designed for pressure refuelling at a rate of 150 gal/min, but also for normal over-wing refuelling. Normal feed is by immersed booster-pump pressure, there being two pumps in each tank, and provi- sion is made for suction feed from each tank in case of booster-pump failure. Each pump can be removed from the under surface of the wing without draining the tanks. Air for tank venting is drawn from a leading-edge intake. Fuel may be jettisoned from the centre-section tank and the two inboard tanks on each side by blowing it out by ram air pressure from the leading-edge intake. Access to the centre-section bag tanks and all integral tanks is by way of removable manholes in the under surface of the wing. Internal baffles are removable for inspection of the extremities of the outer tanks. The four Ghost DGT3 turbojets, each of 5,000 lb static thrust at 10,250 r.p.m., are housed in the wing centre section between the main spars. Their mountings are designed for rapid engine changing and other features which facilitate removal and replacement are quickly detachable air-intake and tail-pipe connections, special joints in the control rods, and good accessibility of the fuel and electrical connections. The complete under surface of the wing, in way of the turbojets, is formed of hinged panels which, when opened, completely expose the instal- lation. There are additional access panels in the top sur- face, for servicing the accessories and for power-plant slinging. The installation is divided into three temperature DIMENSIONS of the D.H. COMET (Type 106). Wing : Area 2,015 sq. ft. Spin .'. 115 ft. Root chord 29ft 6in Tip chord 6ft 9in Thickness chord ratio \\i Sweep-back at ± chord 20 del Fuselage : Length 93ft overall Outside diameter 10ft 3in Inside diameter 9ft 9in Undercarriage : Track (with bogie undercarriage) 28ft 6in Wheelbase 32ft 4in Tail Unit: Span 43ft 4in Height of fin above ground (static) ... ... 27ft lOin The D.H. Ghost (DGT3) of 5,0301b static thrust. The Comet has four of these units and provision is made for two A.T.O. rocket motors. zones, each separated by steel fireproof bulkheads and hav- ing its own ventilation and fire-extinguishing system. Fitted to the under side of the cowling is a mechanical "wipe-off" lever which, as the lowest part, will cut off fuel supply, operate the fire-extinguishing system and cut off electric power in the event of a wheel-up landing. (The nacelle layout was illustrated in Flight of September 29th.) The cabin -pressurization system has a maximum work- ing differential pressure of 8.25 lb/sq in, giving a cabin alti- tude of 8,000ft when the Comet is flying at 40,000ft. The method of pressure control provides for the selection of any desired height up to 8,000ft and any desired rate of change of cabin altitude up to the equivalent of 1,000 ft/min at sea level, provided that the permissible range ol differential pressure is not exceeded. The pressure control equipment is fully duplicated and a safety valve is fitted to limit the pressure to 8.5 lb/sq in. Two inward-relief valves restrict the negative differential pressure to 0.5 lb/in. Fresh air is supplied to the cabin from the compressors of the Ghosts and is passed through coolers (and, when necessary, through a refrigerator) before entering the fuse- lage. With the exception of the refrigerator the supply system in each wing is independent, and either wing can supply adequate air for pressurization. Temperature con- trol of the coolers is automatic, with manual over-ride, but the refrigerator is switched in and out manually as required. Heat for the cabin is supplied by the compression of the air in the Ghosts. Testing of the Comet proceeds at a healthy pace. Last Thursday, October 20th, she completed a 2,000-mile flight over Britain and Europe (as far south as Marseilles) in about four hours, cruising at 36,000—40,000ft, and a pro- gramme of still longer flights to determine fuel consumption is getting under way. By the time these words appear she may, indeed, have returned from a record-breaking trip to Castel Benito. On Saturday evening she joined unostentatiously in the London Airport circuit and requested permission to land. Two flights ensued, the swept-wing jet taking her turn with piston-engined types of half her speed. WALRUS versus WHALE NO one who has read John Gricrson's previous books—Through Russia by Air, High Failure, Jet Flight—will need reminding of the writer's entertaining, unaffected style and of his skill in weaving a thread of humour into authorita- tive dissertations on matters of pilotage, navigation and flight engineering. His new book* preserves the tradition. It is the copiously illustrated account of a season's Antarctic whaling by the v. hale-factory ship Balaena, in which was madr the first serious attempt to employ aircraft for reconnaissance: with a full ilying and maintenance staff under Mr. Grierson's command, two Walruses were accommodated in a deck hangar and cata- pulted off, or flown from the sea, as weather conditions dictated. •" Air Whaler," by John Grierson. Sampson Low, Mariton and Co., Ltd., London. Priee 18s. •_ -, "~-- B 15 " ' ' " : ': The ship was British, but the officers and crew were almost entirely Norwegian. Though several of the harpoon-gunners of the accompanying fleet of catchers were enthusiastic about the aircrews' success in spotting whales, Balaena's captain seems to have been less co-operative: on many occasions, when he considered the weather unpropitious, he forbade flying; and on others, when visibility was good, he refused to stop the ship for flying-off on the plea that the hunt would be interrupted. Grierson and his English aircrews clearly became depressed by these constant " scrubbings," and their frustration is so clearly conveyed that, towards the end, the tale becomes a little depressing to read. Enough experience was gained, however, to convince the author of the value of aircraft in whale-hunting: he thinks that the ideal machine would be the helicopter, which, suitably armed, might be used not only for reconnaissance but for the actual kill.
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