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Aviation History
1956
1956 - 1547.PDF
FLIGHT, 2 November 1956 705 Helicopters of the World ... manual-control form. If the servo-controlselector is switched off, the pilot receives a quick reminder of how the originalDragonfly controls felt. As for stability, the one-armed paper-hanger techniquehas given way to a placid guidance with the collective pitch control, friction-locked for much of the time. A pilot on cross-country can now fold his map,scratch his nose or play with the instru- ments without fear of lurching off courseand altitude. "The collective pitch lever is not quiteso different as the cyclic one; it resembles quite closely that on a Whirlwind, ascould be expected in view of the rotor head similarity. But by comparison, again,with the Dragonfly it has been much tidied up, has a more convenient, shortmovement, is much lighter to operate— though not too sensitive—and is verynicely co-ordinated with control of engine power." • Rotor diam., 49ft 2in; fuselage length, 41ft3in; weight empty, 4,378 lb; gross weight, 5,900 Ib; cruising speed at s.L, 80 m.p.h.; max.permissible speed at s.l., 104 m.p.h.; rate of climb at s.l., l,190ft/min; ceiling, 12,800 ft. Dragonfly Production of the Dragon-fly general-purpose civil/military helicopter (Pratt and Whitney Wasp Junior or AlvisLeonides engine) is now practically com- plete, the type having been succeeded in theWestland line by the Widgeon. Whirlwind The latest basic model ofthe Whirlwind is the Mk 5, powered with the Alvis Leonides Major engine. Acomplete engine-change unit enables the American Wasps and Cyclones of earlierWhirlwinds to be easily replaced in future by the British engine, which is intendedto become standard. Of the Leonides Major's 900 available horse-power only 750is normally used at sea level, and of this some 60 h.p. is used to drive the coolingfan. Maximum power is maintained up to 4,000ft under standard conditions and thepower benefit is, of course, available for operations in tropical climates. The engineis installed in the extreme nose behind two clamshell doors and a simple operationenables it to be swivelled forwards and downwards to give ready access for ser-vicing. The four-blade main rotor is of all-metal construction and the makers claim (Above and right) Westland Wessex. it to be completely immune to temperatureand humidity effects. The blades are matched with a master blade and are indi-vidually interchangeable. Seen at the S.B.A.C. Display this yearwas the new drooped tail cone, already introduced in military Whirlwinds andsoon to be standardized in civil versions. In the original design the Whirlwind's tailcone was parallel to the ground and the droop has been introduced to give moreclearance between the main and tail rotor blades when the helicopter is landing underdifficulties, such as in gusty conditions on the deck of an aircraft carrier, or in anautorotative landing. The modification has involved the addition of a spring-loadedtail skid and the repositioning of the stabilizers, so that they are now parallel tothe ground. The tail-rotor pylon has also been redesigned. The Whirlwind has accommodation fora pilot and observer or co-pilot and up to eight passengers, with luggage. Availablespace is easily adaptable for freight-carry- ing, for rescue operations, ambulance work(with six stretchers and medical attend- ants), or other specialized role. When awinch is required it is fitted on the star- board side above the main cabin door, andthe pilot has an excellent field of view for winching operations. • Rotor diam., 53ft; fuselage length, 41ft 8in;gross weight, 8,000 lb; max. permissible speed at s.l., 109 m.p.h.; normal cruising speed at s.l.,86 m.p.h.; sea level rate of climb at "1 hr" power, 825ft/min: service ceiling, 12,500ft;hovering ceiling (10ft wheel clearance), 7,000ft; max. range with standard tankage (no allow-ances'), 345 miles. Data are for Whirlwind Mk 5. Wessex This completely re-engineereddevelopment of the American Sikorsky S-58 is scheduled to go into service withthe Fleet Air Arm and with other branches of the Services—and possibly with civiloperators also—in 1958. Powered with a Napier Gazelle gas turbine, it will have anexcellent performance, as shown in Col. 3. The naval version will be suitable for anti-submarine work, search and rescue, com- munications and supply, casualty evacua- (Below and right) Westland Westminster. tion and training. In the anti-submarinerole it will carry "special equipment and strike weapons"; alternatively, in additionto a crew of two, accommodation can be provided for twelve passengers and bag-gage, or for eight stretcher cases. The four-blade main and tail rotors both haveall-metal, fully interchangeable blades with a symmetrical aerofoil section and freedomof movement in both vertical and horizon- tal axes. Control is hydraulic servo-assisted. The undercarriage is unusual in having a tailwheel well back along the tail,the final portion of which can itself be folded for carrier stowage. • Overall length, 65ft 9in; weight empty,7,259 lb; normal gross weight, 12,600 lb; max. speed at s.l., over 132 m.p.h.; cruising speedat s.l., over 126 m.p.h.; max. rate of climb at s.L, l,35Oft/min; hovering ceiling in free air,4,500ft; hovering ceiling with ground effect, 8,400ft; range with normal fuel, 440 miles;ceiling (cruising), 6,000ft. Westminster It was announced re-cently that preliminary work on the mas- sive Westminster had made good progressduring the past few months. The first flight-prototype will be a simplified"crane." Two Napier Eland gas turbines are specified and the ultimate version willseat forty passengers or carry thirty-two stretcher cases. The layout of the aircraft—featuring a single main rotor driven by the twin turbines mounted on top of thefuselage—was evolved by Westland de- signers "to take full advantage of thecompact nature of British rear-drive gas turbines and to give maximum hoveringperformance." • Gross weight, 33,000 lb; disposable load,13,000 lb; range at 149 m.p.h., 355 miles.
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