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The Czerwiński-Shenstone Harbinger, aka the Shenstone-Czerwiński Harbinger or the Shenstone Harbinger was a high performance tandem seat sailplane designed in the UK. Only two were built, one in the UK and one in Canada. The latter did not fly until 1975, being under construction for 26 years; the former remained active until at least 1994. ==Design and development== In 1947 the British Gliding Association held a competition for a two seat glider design.〔 The tandem seat Harbinger was designed jointly by Waclaw Czerwiński, who had already developed several gliders in Poland before World War II,〔 and Canadian Beverley Shenstone, who had worked in Germany on the Junkers Ju 52 then later, in the UK, on the Spitfire.〔〔 The Harbinger came fifth in the competition, which the Kendall Crabpot won.〔 The Harbinger was, apart from its wing mountings, an all wood aircraft. It had braced, high-set demountable wings each built around a single main spar. These were plywood covered ahead of the spar and fabric covered behind. The inner sections, which together provided about 11 ft (3.35 m) of the total 60 ft (18.3 m) span, had constant chord and were swept forward at about 17°, partly to bring the centre of gravity (cg) forward and partly to enhance upward visibility from the rear seat. These sections were thinnest at the root, to minimise wing-fuselage aerodynamic turbulence. The outer wing panels were tapered, though the leading edges were unswept, and had elliptical wing tips. The outer panels carried ailerons and spoilers, each composed of four pairs of small square plates which rotated out above and below the wing, were situated at mid-chord across the junction between inner and outer panels.〔〔 The wing roots were mounted to the front and rear of a horizontal metal rectangular frame built into the fuselage. On each side another pair of horizontal braces ran from the rear root connection to a point on the spar at the inner-outer panel junction. The front member of the fuselage frame was also shared by a second, vertical square fuselage frame. The external metal tube lift struts were attached to its lower corners. The rest of the fuselage was all-wood and plywood covered, oval in cross-section and tapering toward the tail. As designed, the cockpit canopy was multi-piece, rounded in profile and extended to the nose. The tail surfaces were conventional, with the tailplane on the upper fuselage. The rudder and elevators were unbalanced, the former extending to the bottom of the fuselage and moving in a small elevator cut-out. A central landing skid ran from the nose to below the bottom of the lift strut where there was a single, part exposed, fixed wheel. The extreme rear fuselage had a tail bumper extension.〔〔〔 Two Harbingers were built, both over long periods, one in Canada and on in the UK. Construction of the latter began in February 1949 and the other was started at about the same time. The UK aircraft was built at Camphill, Great Hucklow, the home of the Derbyshire and Lancashire Gliding Club by Fred Coleman and was not completed until the Summer of 1957, when it was discovered that as designed the cg was too far aft. To counter this the forward fuselage was extended by 15 in (380 mm) by increasing the space between the seats. The extension resulted in a revised, more vertical canopy windscreen. It also increased the weight by about 45 lb (20.4 kg); in addition, about 25 lb (11.4 kg) of lead ballast in the nose was needed to get the cg to within the acceptable range. Construction of the Canadian aircraft was not so far advanced in 1957 and its builders chose to retain the original design fuselage but add slight rearward sweep to the outer wing leading edge, moving the center of pressure backwards. This aircraft lacked the spoilers but also the excess weight of the British aircraft, coming in close to the original design estimate.〔〔 The UK aircraft, which has become known as the Harbinger Mk 2, first flew on 26 July 1958 at Hucknall; the Canadian Harbinger Mk 1 did not fly until 1975, some 26 years after building began.〔 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「Czerwiński-Shenstone Harbinger」の詳細全文を読む スポンサード リンク
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