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The Handley Page Dart Herald was a 1950s British turboprop passenger aircraft. ==Design and development== In the mid-1950s Handley Page developed a new fast short-range regional airliner, intended to replace the venerable Douglas DC-3, particularly in third-world countries.〔''Flight '' 19 August 1955, p. 260.〕 The design, originally known as the HPR-3 Herald, emanated from the drawing office at Handley Page (Reading) Limited—the former Miles Aircraft factory site, which had developed an earlier airliner design, the Miles Marathon. The Herald was an extensive re-development of the original concept of the Marathon, notable for its high mounted wing.〔Payne 1997, pp. 336–337.〕 The HP Reading division succeeded in producing a modern design with excellent flight and performance characteristics. However, the company made a serious misjudgement which was, in the end, to cost the company dearly, and like some other classic British aircraft of the time, the Herald missed its chance. After extensive consultation with DC-3 operators, it was decided to power the new airliner with piston engines, rather than turboprops, which were considered risky by the small airlines at which the HPR.3 was aimed. Handley Page preferred a four-engined design, which led to the new 870 hp (650 kW) Alvis Leonides Major 14-cylinder radial engine, driving three-bladed propellers being chosen for the HPR.3.〔Payne 1997, p. 336.〕〔Barnes 1976, p. 531.〕 At almost the same time, the Dutch company Fokker made the opposite choice for its competitor for the same market, choosing to power the F27 Friendship with two Rolls-Royce Darts.〔 The HPR.3 could carry up to 44 passengers in its pressurised cabin, which could be quickly converted to allow the carrying of freight, with the aircraft's high wing, nosewheel undercarriage and large doors at the front and rear of the cabin making the loading of cargo relatively simple. Large flaps were fitted to give good short take-off and landing characteristics.〔Barnes 1976, p. 534.〕〔''Flight'' 19 August 1955, pp. 260–265.〕 It was designed to cruise at a speed of 224 mph (360 km/h), had a range of 1,640 mi (2,640 km),〔Barnes 1976, p. 535.〕 could land and take-off in a distance of less than 500 yards (460 m) and had an initial rate of climb of over 1,800 ft/min.〔''Flight'' 19 August 1955, p. 263.〕 At first, it seemed that Handley Page had made the right choices with the HPR.3, which was named "Herald" in August 1954, this being a name easily translatable into French and Spanish.〔Barnes 1976, p. 532.〕 Extensive work by the sales team had produced considerable interest from potential customers, and Handley Page had 29 orders for the Herald (from Queensland Airlines, Australian National Airways, and Lloyd Aéreo Colombiano) by the time the first prototype made its maiden flight from Radlett on 25 August 1955, three months ahead of the first flight of the Friendship. Break-even was expected after the sale of 75 aircraft and Handley Page expected total sales of up to 300 Heralds,〔Barnes 1976, pp. 532–533.〕〔Mellberg 2007, p. 64.〕〔Payne 1997, p. 337.〕 with first deliveries expected to British independent airline Air Kruise in 1958.〔''Flight'' 27 July 1956, p. 149.〕 By now, however, the Rolls-Royce Dart turboprop engine had shown proven success in the Vickers Viscount. Queensland Airlines and Australian National Airways cancelled their orders for Heralds in favour of turboprop-powered Friendships, while the Lloyd Aéreo Colombiano contract was stopped due to currency problems and Air Kruise's interest was ended when it was taken over by British Aviation Services.〔Barnes 1976, p. 534.〕〔 Before the second prototype had been completed, Handley Page was faced with the fact that it had no orders for the Herald, and that the market had changed and wanted turboprops.〔〔 There had already been a very substantial investment in the Herald project, such that the Management held a meeting to discuss continuation. Handley Page decided to press ahead with the Herald project, in an effort to recover the investment; announcing a new uprated version powered by the Rolls-Royce Dart.〔''Flight'', 10 May 1957, p. 644.〕〔''Flight'' 17 May 1957, p. 652.〕 The revised aircraft, now designated the HPR.7 Dart Herald, was powered by 1,910 shp Dart 527 engines driving 12 ft 6 in (3.81 m) variable pitch four-blade Dowty Rotol props,〔''Flight'' 25 July 1958, p. 134.〕 and the fuselage was lengthened by 20 in (51 cm), while other improvements included increased fuel capacity.〔 The first prototype was converted to Dart Herald standard, making its maiden flight on 11 March 1958,〔Barnes 1976, p. 537.〕 with the first production aircraft flying on 30 October 1959. The initial Series 100 version of the Dart Herald was certified in April 1958.〔 Basic price in 1960 was around £185,000.〔http://www.flightglobal.com/pdfarchive/view/1960/1960%20-%202696.html〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Handley Page Dart Herald」の詳細全文を読む スポンサード リンク
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