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Aviation History
1955
1955 - 1855.PDF
978 FLIGHT, 30 December 1955 WIDGEON AND WHIRLWIND . . . minor improvements are being made. Eventually a spring feelsystem with control trimmers is to be added. A cabin-heater system is also to be fitted at a future date, the ducting for whichis built-in to the cabin underfloor. The weight penalty of the new rotor hub has been almostexactly balanced by a weight saving in the new nose structure, if the Dragonfly and Widgeon are compared to the same standard.Thus the empty weights are approximately equal, and the increase in gross weight from 5,700 to 5,900 Ib can be utilized almostentirely for the extra payload, which gives a civil five-seater. For Service use, the most useful features of the Widgeon are(1) the ability to rescue a crew of three persons (using winch and crewman). This was not possible in the standard Dragonfly dueto the e.g. movement; (2) its possible use as an ambulance machine, carrying two standard general-service stretchers (loaded throughthe port nose-door) and medical attendant; (3) the side-by-side seating and dual control for pilot training. As mentioned earlier, a large proportion of the existing Dragon-fly has been retained in the design of the Widgeon, and the changes are such that the modification of Dragonfly aircraft to Widgeonstandard is considered a practical proposition. A detailed scheme for such modification has been devised by the company. At Yeoyil, the second Widgeon is now almost complete. It isG-AKTW, originally the first S-51 to be built by Westlands, and it is to be followed by a third Widgeon, the front fuselage forwhich is now under construction. Whirlwind Mk. 5 (Alvis Leonides Major).—At Yeovil, the WESTLAND WIDGEON (civil version) (Alvis Leonides 521/1 engine) Weight empty ... , ... 4,378 1b All-up weight 5,900 Ib Disc loading 3.10lb/sqft Power loading 11.35 Ib/b.h.p. Flight limit load factor 2.84g Design sinking speed ... ... ... ... ... ... ... 12ft/sec Overall length, unfolded min. 45ft 6in Height 12ft 11fin Wheel track t Wheelbase 10ft 1 in Rotors Main Tail Rotor diameter 49ft 2in 8fc Sin Disc area 1,900 sq ft 55.6 sq ft Tip speed at 3,000 e.r.p.m. ... 520ft/sec 586ft/sec Engine details: Alvis Leonides 521/1 (6i Ib boost) Five-minute rating ... 520 b.h.p. at 43in. Hg. at 3,000 e.r.p.m. One-hour rating... ... ... ... ... 470 b.h.p. at 38in. Hg. at 6,000ft at 2,900 e.r.p.m. Max. weak mixture cruise 375 b.h.p. at 31in. Hg. at 11,750ft at 2,800 e.r.p.m. Alvis Leonides 523 1 (8 Ib boost) Five-minute rating ... 560 b.h.p. at 46in. Hg. at 3,000 e.r.p.m. Performance at 5,900 Ib with Alvis Leonides S21/1 Normal cruising speed at sea level 70 kt T.A.S. Max. permissible speed at sea level ... ... ... ... ... 90 kt T.A.S. Best rate of climb at sea level 96Oft/min Vertical rate of climb at sea level 170ft/min Hovering ceiling (free air) 4,800ft Hovering ceiling (10-ft wheel clearance) ... 7,500ft Service ceiling (100ft/min R.O.C.) 10,000ft Cruising fuel consumption , 22 gal/hr Still air range (full fuel 83 gal) 260 n. miles A pleasing air view of the first Leonides Major Whirlwind, XJ396 (ground view of engine installation at foot of page). A second such installation is shortly to be made for type-test purposes at Yeovil. Leonides Major-powered Whirlwind Mk. 5, XJ396, has loggedsome thirty hours' running time, over half of which has been in the air. The object has been to produce a Leonides installationwhich is a complete engine-change unit, enabling the Pratt and Whitney R-1340 Wasps and Wright Cyclones of earlier Whirl-winds to be replaced easily in future by the Alvis unit, which is to become the standard Whirlwind powerplant. Compared with the Cyclone-powered Whirlwind Mk. 3, therotor speed of the Mk. 5 is the same; the engine speed-range is different and so the reduction gearing has been altered. Only720-750 h.p. of the Major's 870 h.p. is used normally at sea level in this installation, of which some 60 h.p. is used to drivethe cooling fan. Maximum power is maintained up to 4,000ft under standard conditions, and the power benefit is of courseavailable for operations in tropical countries. Helicopter versions of the Leonides Major are basically similarto those employed in fixed-wing aircraft, except that they have no airscrew reduction gearbox. The Whilrwind version (A.Le.M.5-10) is different from that used on Bristol helicopters in having opposite direction of rotation. Aft of the firewall, in the Whirl-wind installation, the Mk. 5 is no different from the Mk. 3 except for the reduction gear. A specimen of the Leonides Major intended for Whirlwind useis at present undergoing 50 hours of type-test bench-running at the Alvis factory in Coventry. When these tests are complete,this engine is to be fitted into another Whirlwind at Yeovil for further type-testing of transmission, etc. (involving 50 hrground-running and 50 hr in flight). This will be followed by the fitting of subsequent Leonides Majors to a proportion ofthe Royal Navy's Whirlwinds. The company anticipates clearance for the Whirlwind Mk. 5at 7,800 lb gross weight in the spring of 1956, and for the civil version, the S-55 Series 2, at the same weight in the summer. Subject to satisfactory completion of the type test, the AlvisLeonides Major should enter service in the Whirlwind Mk. 5 with an overhaul life, as on most new powerplants, of some 250 hr. WESTLAND WHIRLWIND (ALVIS LEONIDES MAJOR A.Le.M. 5-10) Performance data (based on standard I.C.A.N. conditions, including the effect of a four-per-cent drop on normal engine power; maximum all-up weight for civil operations, 8,000 Ib). All-up weight 7,5001b 8,0001b Max. permissible T.A.S. (sea level) 95 kt 95 kt Normal cruising T.A.S. (sea level) ..; ... ... 75 kt 75 kt Best sea-level rate of climb: Using one-hour power 1,035ft/min 825ft/mjn Using max. contin. power 775ft/min 577ft/min Fuel consumption (at 75 kt) 3i gal/hr 39 gal/hr Service ceiling 14,500ft 12,500ft Hovering ceiling (10ft wheel clearance) ... 9,000ft 7,000ft Max. range with standard tankage (no allowances) 320 n. miles 300 n. miles Dimensions: - Length ... ..^ 42ft Oin Main rotor diameter 53ft Oin Height (main rotor) ... ... ... ... ... ... ... 13ft 2^in Height (tail rotor) 15ft S|in Main wheel track 11ft 3in Nose wheel track ... ... ... ~ 4ft 8in
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