The helicopter 'twins' produced by Westland as the Scout and Wasp originated in November 1957 when Saunders-Roe Ltd. began its design of a private venture for a Skeeter development and replacement. Two prototypes of the aircraft, then known as the Saro P.531, were begun early in 1958, the first (G-APNU) flying on 20 July and the second (G-APNV) on 30 September 1958. Several Skeeter components were used in their construction, including the tailboom, short-legged tricycle undercarriage and rotor blades (the P.531 having a 4-blade assembly). Both prototypes were powered by Blackburn-built Turmo 603 shaft turbines, derated to 325shp.

Westland, after acquiring Saunders-Roe in 1959, took development an important stage further by completing two more prototypes with double the power and various other changes including a skid undercarriage. A Blackburn A129 (later known as the Nimbus) derated to 635shp powered G-APVL, which flew on 9 August 1959, while G-APVM, flown on 3 May 1960, was given a Gnome H.1000 engine derated to 685shp. The first firm order for this general purpose helicopter came from the Army Air Corps, a pre-series batch of P.531-2 Mk.1's basically similar to G-APVL being ordered in 1959. The first of these was flown on 4 August 1960, and in the following month a substantial Army order was placed for the type as the Scout AH Mk.1. Delivered from spring 1963, these are 5-seaters with Nimbus 101 or 102 engines and skid landing gear. They have replaced the Skeeter both at home and abroad and are employed for duties that include passenger or freight transport, liaison, search and rescue, and training. The Scout can also be used for casualty evacuation, carrying 2 stretchers inside the cabin and 2 more supported externally. Up to the spring of 1968 about one hundred and fifty Scouts had been built, these including deliveries to the Royal Australian Navy (two for shipborne survey work), Royal Jordanian Air Force (three), and the police departments of Bahrain (two) and Uganda (two).

Parallel development of the Wasp anti-submarine version has taken a little longer, due to exhaustive Naval trials carried out from November 1959 with a modified G-APNV and two specially-built P.531-0/N's, which also had Turmo engines but were fitted with a long-stroke quadricycle wheel undercarriage as well as landing skids. The Wasp is designed to operate from platforms on the rear decks of frigates, primarily as an extension of the ship's ability to attack submarines, but carrying no search gear. Production Wasps differ from the Scout in having the 710shp (derated) Nimbus 103 or 104 engine, long-stroke, fully-castoring wheel undercarriage (but no skids) and a half-tailplane at the top of the tail rotor pylon on the starboard side. (The Scout has a full tailplane below the tailboom.) The Wasp's main rotor blades and its entire tail section can be folded for stowage on ship. A weapon load of some 244kg can be attached to the underside between the undercarriage legs; this may comprise two Mk.44 homing torpedoes or an equivalent weight of depth charges or bombs. The Wasp HAS Mk.1 entered service in October 1963, and first production machines were allocated to No.829 Squadron and deployed singly aboard the Royal Navy's seven Tribal class and seven Leander class frigates. Other Wasps have been ordered by the navies of Brazil (three), the Netherlands (twelve), New Zealand (two) and South Africa (ten).

K.Munson "Helicopters And Other Rotorcraft Since 1907", 1968

Development of the Wasp/Scout family was initiated by Saro in 1957, with the aim of developing an aircraft based on the earlier Skeeter helicopter, but of more modern design, above all in terms of the powerplant. The result was the P.531 project, which aimed to use various components of the Skeeter; the first of two prototypes, both powered by a 400shp Turbomeca Turmo 603, flew on 20 July 1958. In 1959, Westland acquired Saro and decided to continue development of this interesting light helicopter. Another two prototypes were built, the first with a 1050shp Bristol Siddeley Nimbus engine derated to 635shp, and the other with a de Havilland Gnome H.1000 turbine derated to 685shp.

The British Army ordered a pre-production model and this was followed in September 1960 by an order for 66 of the P.531-2 Scout AH Mk.1 with 968shp Rolls-Royce Nimbus turbine engines (derated to 685shp). Another order was placed for 40 helicopters in September 1964.

The Scout was suited to all the tasks of a lightweight helicopter: observation, liaison, training, SAR. Several orders were also received from abroad: Royal Australian Navy (2), Royal Jordanian Air Force (3), Uganda (2) and Bahrain (2). The last two countries used them for police work. A total of 150 Scouts were built. Although its characteristics were not outstanding, the Scout fulfilled a role in the British Army which was played by the Bell 206 in many other armies, and has only recently been superseded by the Westland Lynx.

Development of the naval version of the Wasp proceeded more-or-less in parallel, but took longer. The Royal Navy used one of the prototypes, suitably modified with higher skids suitable for deck landings, and also ordered two P.531s powered by Nimbus turbine engines for deck landing and operational trials. The three aircraft performed exhaustive take-off and landing trials from the escort vessel HMS Undaunted in November 1959. The definitive Wasp was mainly intended for ASW from frigates of the Tribal and Leander classes and similar vessels; for this purpose it could carry one or two 122kg torpedoes or 250kg of depth charges. In September 1961, the type was ordered for the Royal Navy under the name Wasp HAS Mk.1 (the first flew on 28 October 1962 with a 968shp Nimbus engine derated to 710shp) and went into service in October 1963, performing 200 day and night landings on HMS Nubian.

The Wasp differed from the Scout mainly in the long-stroke landing gear with fully castoring wheels and the small tailplane on the starboard side of the tail rotor pylon. The main rotor and tail boom could be folded for stowage on board ship.

The Wasp, of which 63 were built, was primarily an antisubmarine helicopter in the "killer" role. It has been replaced by the Lynx in the Royal Navy but the following navies are still operating the Wasp: South Africa, Brazil, New Zealand, and Indonesia (which purchased ten second-hand aircraft from Holland when the latter's navy replaced its Wasp fleet with the Westland Lynx).

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

Strengthening its grip on the British rotary-wing aircraft market, Westland acquired Saunders-Roe Ltd in August 1959. Saro itself had taken over the Cierva Autogiro Company in January 1951 and continued development of the Cierva Skeeter light helicopter. Experience with production of this aircraft led to the Saunders-Roe P.531 prototypes, the first of them flown on 20 July 1958, and was followed in 1959 by an Army Air Corps order for pre-production P.531-2 Mk 1 aircraft. Following extensive evaluation, this five-seat utility light helicopter was ordered into production as the Scout AH.Mk 1, which began to enter service in early 1963, a total of 150 being built. In addition, small numbers were built for the Royal Australian Navy, Royal Jordanian air force, and the police departments of Bahrain and Uganda. Parallel development of the P.531 resulted in production of the Wasp HAS.Mk 1 for the Royal Navy (originally designated Sea Scout HAS.Mk 1). This differed from the army Scout by having quadricycle landing gear instead of skids, and folding rotor blades and tail section to facilitate shipboard stowage. A total of 98 Wasps was built for the Royal Navy, these first entering service in the summer of 1963. Wasps were also supplied to the navies of Brazil, the Netherlands, New Zealand and South Africa. As powered by a 783kW de-rated Rolls-Royce/Bristol Nimbus 103 or 104 turboshaft engine, the Westland Wasp had a maximum speed of 193km/h at sea level. Ten former Dutch aircraft were supplied to the Indonesian navy, after refurbishment by Westland, and are still in use along with those of the Royal New Zealand Navy. The only surviving Scout operator in 1993 is the British army. Thirty-eight active AH.Mk Is, with more in storage, remain in use with Nos 658 Sqn at Netheravon, 660 Sqn at Hong Kong and Brunei, and 666 Sqn (TA) at Middle Wallop.

D.Donald "The Complete Encyclopedia of World Aircraft", 1997

Developed for naval use from the Westland Scout. Three scout prototypes modified with higher skids engaged in deck landings and operational trials from 1959.Ordered by Royal Navy in September 1961.

VERSIONS

WASP HAS. Mk 1: Version for Royal Navy, with folding tail and special landing gear for deck operations. Intended primarily for operation from small platforms on frigates and destroyers in anti-submarine weapon-carrying role, the normal load being two Mk 44 torpedoes. Also employed for Search and Rescue, training and other subsidiary duties. First Wasp HAS. Mk 1 for Royal Navy flew 28 October 1962, and deliveries began in second half of 1963.

DESIGN FEATURES: Four-blade main rotor, with all-metal blades carried on fully articulated hub. Torsion blade suspension system. Two-blade tail rotor with metal blades. Rotors driven through steel shafting. Primary gearbox at rear of engine, secondary gearbox at base of pylon, angle gearbox at base of fin, tail rotor gearbox at top of fin. Main rotor/engine rpm 1:71. Tail rotor/engine rpm ratio 1:15.

FLYING CONTROLS: Main rotor hub has drag and flapping hinges. Rotor brake standard. Tail rotor has flapping hinge.

STRUCTURE: The fuselage is a conventional aluminium alloy stressed skin structure. Front section forms the cabin, fuel tank bays and aft compartment. Rear section is a tapered boom terminating in a fin which carries the tail rotor. Horizontal stabiliser of light-alloy construction mounted on starboard side of fin opposite tail rotor.

LANDING GEAR: Non-retractable four-wheel type. All four wheels castor and are carried on Lockheed shock-absorber struts. All wheels and tubeless tyres are Dunlop, size 15 x 4.75-6.5, pressure 4.22kg/cm². Dunlop dog clutch brakes. Flotation gear standard.

POWER PLANT: One 710shp (derated) Rolls-Royce Bristol Nimbus 503 turboshaft engine, mounted above fuselage to rear of cabin. Fuel in three interconnected flexible tanks in fuselage below main rotor, with total capacity of 705 litres. Refuelling point on starboard side of decking. Oil capacity 7 litres.

ACCOMODATION: Two seats side by side at front of cabin, with bench seat for three persons at rear. Four doors, by front and rear seats on each side of cabin. Rear seats removable for cargo carrying. Heater standard.

SYSTEMS: Delaney Galley/Westland 1 kW cabin heating and windscreen demisting system. Hydraulic system, pressure 73.9 bars, operating servo jacks for rotor head controls and rotor brake. No pneumatic system. 28V DC electrical supply from engine-driven generator. Limited supply by 15 or 23 Ah battery. Three-phase 115V 400Hz AC provided by inverter.

ELECTRONICS AND EQUIPMENT: PTR.170 and PV.141 UHF and UHF homing radio, and standby UHF. Intercom taken from side tone of UHF T/R. Blind-flying instrumentation standard. Equipment includes autostabilisation/autopilot system, with radio altimeter.

Jane's Helicopter Markets and Systems

- Wasp deliveries began in 1963 after more than 200 test deck landings had been completed.

- The Royal Navy received a total of 98 Wasps; the last was retired in 1988.

- The second crewman acted as navigator, gunner, missile operator and winchman.

- Wasps were ordered by the navies of Brazil, South Africa, New Zealand and the Netherlands.

- Nine ships operated Wasps during the Falklands War of 1982.

- Wasps flew in support of British expeditions in Antarctica.

- A Scout pilot won the Distinguished Flying Cross in tho Falklands for flying under fire to rescue a severely injured soldier.

- Total production of the Westland Scout numbered 150 aircrafl.

- King Hussein of Jordan had a Scout for his own personal use.

- The Empire Test Pilot School at Boscombe Down flew a Scout in their 'raspberry ripple' colour scheme.

- Two Scouts were operated from survey ships by the Royal Australian Navy.

- A Scout still flies with the British Army's historic flight at Middle Wallop.