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Aviation History
1955
1955 - 1854.PDF
FLIGHT, 30 December 1955 977 Cockpit layout of the Widgeon. Since this photograph was a second set of controls has been fitted in the left-hand seat position. Dragonfly lower main gearbox, the only modifications required being an amount of local machining of the lower end of the rotor shaft, reconnection of the oil supply lines and detail changes to the pylon steady strut attachments. The main rotor blades have been constructed from standard leading-edge extrusion and trail- ing-edge sections used for the Whirlwind. They are larger than those of the Dragonfly and smaller than those of the Whirlwind, providing a sweep of 49ft 2in diameter. No other changes have been made to the normal Dragonflytransmission, the Leonides 521/1 powerplant installation remain- ing unaltered. The possible future use of the Leonides 523/1engine, with higher max. continuous power, appears attractive, for it would give the Widgeon improved cruise and climb performance. The cabin section of the S-51 has always been a separate air-frame sub-assembly, consisting of the fuselage ahead of the fire- proof bulkhead at the base of the rotor pylon structure. Thisbulkhead is an inverted egg-shaped section, the cabin of the Dragonfly providing seating for three abreast at the rear of thecabin and then narrowing to accommodate the centrally placed pilot in the nose. In revising the cabin to the form of the Widgeon,the rear-bulkhead fuselage cross-section has been retained and has been kept constant forward to the nose, thus providing spacefor the second pilot's seat. The front windscreens are flat and have been brought closer to the pilot's eye, and the pilot's viewsideways and downward is improved with bulged side-windows. Certainly apparent from an inspection of Dragonfly andWidgeon, and doubtless also apparent from flying the two machines, is the fact that the control system has been cleaned-upand improved. The central control-run tunnel is now below floor level and so does not take up space in the cabin proper. Fromthe pilot's point of view there is now less friction in the flying- control system; push-pull rods and levers having largely beensubstituted for the previous cable controls. Only in the tail-rotor controls are cables still used. The rudderpedals are connected via a tee-lever and rocker lever to a push-pull rod linkage to an underfloor quadrant, from which cables run viaa pulley system to the tail-rotor cable drum. At the base of the control column, fore-and-aft and lateral control push-pull rodsrun from a torque shaft and tee-lever respectively to a mixing unit at the base of the rear cabin bulkhead. From rocker levers at themixing unit vertical push-pull rods are carried up the bulkhead to larger rocker levers, which carry a final rod connection to thehydraulic servo-jacks and so to the rotor-hub. The collective-pitch lever torque-shaft has a push-pull rod linkage via a bell-crank leverto the mixing unit, from which the linkage is as described above. The flying controls at the rotor-hub are the same hydraulicservo-jacks (with no feedback) as used hitherto on the Dragonfly and Whirlwind, and are powered from the same source on thetail-rotor transmission shaft. Manual reversion is provided. The control system is fully duplicated, the dual collective and cyclicpitch levers being accommodated on appropriate cross-shafts. The directional-control pedestals are manually adjustable, andfrom them the hanging-type rudder pedals are pivoted. Also fitted in the Widgeon is an improved form of instrument panel.At present the dual control system is being flight-tested and Two views of the prototype Widgeon G-ALIK, illustrating the com- pletely redesigned front fuselage which is of constant width. The initial batch will include two further machines.
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