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Aviation History
1957
1957 - 0522.PDF
524 FLIGHT CORRESPONDENCE ... A curious feature of the Ensign's main wing spar, not previouslypublicized, is that it was possible for the flight engineer to crawl into the spar through a 4ft-square opening, whenever visual enginechecks were required while in flight. But the noise inside the spar was quite indescribable and did not encourage frequent use.Although synchronization of the four Cyclone engines could be obtained through the rev indicators, the latter were not alwaysreliable, and the flight engineer often had to synchronize them by ear. Another unique feature of Ensign maintenance, common toboth marks, was the nacelle platforms that were actually part of the nacelle, each engine having two, one on each side. The photo-graph enclosed clearly shows this feature on G-ADSV Explorer during refuelling operations at Takoradi. The Ensign's main undercarriage was, perhaps, the most interest-ing feature of all. Designed by the A.W.A. team, it was built with the assistance of Automotive Products, who supplied the Lockheedhydraulic retracting gear; and by Aircraft Components, whose patented hydraulic jack carried the undercarriage entirely by meansof the retracting strut. The oleo legs were designed and manu- factured by A.W.A. from an especially strong Swedish steel, andthe whole unit was ingeniously designed to lie completely flat when in the retracted position. This was achieved by folding the rearstruts of each unit, so that the wheels travelled backwards and upwards into the engine fairings, coming to rest behind the mainwing spar. The attention required to ensure that the complicated electrical and hydraulic systems functioned satisfactorily was reallya job for a scientist. In an emergency, the winding-down of the undercarriage was a man-sized job that took approximately 20 min!As Messrs. Dobson and Humphreys mention in their letters (March 15), the method of retracting and lowering this massiveundercarriage was a fascinating sight; but it is not really surprising that the hydraulic jack found it hard work—in some cases the timefor retraction took as long as ninety seconds. Mentioned in Mr. Peter Moss's letter are the hinged nacelle-covers which formed maintenance platforms for *he engines of the Ensigns. A rather strange coincidence has recently been discovered: thedates of obsolescence for all Ensigns was fixed by Imperial Airways to occur seven years from the date of delivery. This rendered themdue for replacement in 1945-6, and it was in 1945 that the sur- viving seven Ensigns were withdrawn from service and returnedto the U.K. for disposal in 1946! Built like battleships, Ensigns never suffered structural failure;nor did they cause loss to human life, even in a forced landing. They gave long and invaluable service when most needed andwere the cause of awe and envy with American personnel when they landed at the odd U.S.A.A.F. base. This reminds me of thestory told by Captain Prichard, who parked his Ensign alongside a Flying Fortress on one occasion: ". . . the American ControlOfficer gazed for a while at the two aircraft, then with a gesture towards the Ensign, he remarked, 'Gee, what a hunk of rivets!' " Ruislip, Middlesex. PETER W. MOSS. Cinderella DC-3sI FEEL I must express my appreciation to your contributor"H. W." for his history (Flight, March 15) of ex-R.A.F. Dakota KN55O's transformation into Aden Airways' newest DC-3.G-AOJI. The author's report is, in my opinion, a tribute to the ingenuity,coupled with boldness of enterprise, shown by Eagle Aircraft Ser- vices, Ltd. Perhaps it is out of place to compare the renovationof anything so prosaic as an aircraft to the restoration of a paint- ing; and yet there is indeed a similarity between the two. Therestorers, whether they be engineers or paint-and-canvas experts, start with a worn and dirty relic and, by skilled workmanship,restore it once again into a thing of beauty. From the purely aesthetic angle, the C-47/DC-3 unquestion-ably repays restoration—and this despite the fact that its basically unchanged exterior design goes back to 1935.Eagle, I understand, have also recently rebuilt yet another ex-R.A.F. Dakota. This is G-AOYE, which, starting life in 1943as a U.S.A.A.F. C-47B (serial No. 42-24166), was transferred to the R.A.F. in 1944, becoming FL510 in Transport Command.Its constructors' serial number is 10028. In conclusion, an American correspondent has recently told methat even today there are scores of "Gooney Birds" (the U.S.A.F. nickname for C-47s) lying about on various Pacific islands and inBurma, Thailand, Indonesia, the Philippines and even, possibly, in remote parts of India and China. One of the biggest (and mostsuccessful) U.S. firms specializing particularly in converting C-47s to executive DC-3s—Remmert-Werner Inc. of St. Louis—have"seriously considered" a combined project (with U.S.A.F. assist- ance) to bring back to the U.S.A. a "limited number of theseC-47 relics." Nairobi, Kenya. DENNIS M. POWELL. MILES H.D.M. 105 (continued from page 505) The diagonal and vertical struts and the stub wing largely repeatthe construction of the wing. The diagonal has a single light diaphragm spar with extruded T-section booms and pressedflanged lightened ribs. The nose section is covered by rolled L72 skin to form a torsion box and light skinning is used aft of thespar. This construction is largely "blind" and use is made throughout the wing and spar construction of Avdel countersunkrivets which contain an integral mandrel that is afterwards milled off: the skin finish obtained is excellent. The stub wing—with two spars—and the vertical strut (withthree) follow the well-proven construction methods already out- lined. The vertical strut is sealed to form an integral 13-gallontank on each side. Fuel is lifted by the engine-driven pump; no booster pump is required. Although a total capacity of 26 gal isadequate for the experimental and test work that the H.D.M. 105 is required to do, consideration is being given to an engine-nacellefuel installation and, for the H.D.M. 106, a system of much greater capacity. A longer nacelle is in any case to be fitted for aero-dynamic reasons. Mechanical contents-gauging of such a deep tank also presents some problems; Miles' approach is to measurethe pressure head of fuel in the tank. Nearly all the remainder of this aircraft is standard Aerovan:the same undercarriage (moved outboard to below the vertical strut which carries the loads through to the centre section), the samefuselage, cockpit and tailplane. The end-plate fins have been extended below the tailplane, but—unless single-engined flyingindicates a need tor their retention—these may later be abbre- viated. It is also proposed to fit a servo tab to reduce therudder-pedal loads. Since the aircraft first flew on March 31, steady progress withflight testing has been made. Early experience promises very satisfactory fulfilment of the wind-tunnel-based performancefigures given below. Exploitation of this experimental prototype will be in the hands of a joint company formed by F. G. Milesand Hurel Dubois, to be called H.D. et M. (Aviation), Ltd. The projected Lycoming GO-480-powered H.D.M. 106 (some detailswere given in Flight for August 31, 1956), which is, in effect, a larger and more powerful production model, would follow thegeneral layout of the 105 but would be of all-metal construction with a larger fuselage that would accommodate fifteen passengersor freight. A typical load, made possible by the rear loading door, would be a medium-sized motor car. Another project is theH.D.M. 107, a twin T-33 turboprop army support version with similar aerodynamically conferred economy, short take-off andpayload versatility features of this happy Anglo-French combina- tion. But Miles' resurgence does not only embrace light freighters;on Monday last week, Miles' other new prototype, the sleek M.100 Student, left the hangar for the first time to do engine runs, andanother in the long line of Miles trainers took a step nearer the date of its first flight. Shoreham is being firmly planted on theindustry's airfields map. H.D.M. 105 Two Blackburn Cirrus Majors Dimensions: Span, 75ft 4in; length, 34 ft 4 in; gross wing area (exclusive of struts), 279 sq ft; aspect ratio, 20.5. Weights: Gross weight, 6,000 Ib. Payload, 2,000 Ib. Performance: Take-off (flaps at 30 deg) ground run, 284 yd; distance to 50ft, 644 yd. Climb, both engines, 657ft/min at sea level: 55Oft/mtn at 1,500ft. Single- engine climb at sea level (20 deg flap), 88ft;min. Single-engine climb at 1,500ft (20 deg flap), 57ft/min. Service ceiling, both engines, 16,200ft. Max. sea level speed, 127 m.p.h. Cruising speed at 2.200 r.p.m. at 3,000ft, 116 m.p.h. (These performance figures are based on propellers as fitted to the Aerovan. Higher maximum and cruising speeds are obtainable with propellers of coarser pitch.)
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