Westland Scout / Wasp
The Westland 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 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. 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.
Controls have main rotor hub has drag and flapping hinges. Rotor brake standard. Tail rotor has flapping hinge.
Landing gear is a 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.
The engine is 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.
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 include 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.
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 an order for 66 of the P.531-2 Scout AH Mk.1 with 968shp Rolls-Royce Nimbus turbine engines (derated to 685shp) 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 replaced the Skeeter both at home and abroad and were 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). King Hussein of Jordan had a Scout for his own personal use.
Another order was placed for 40 helicopters in September 1964.
The only Scout operator in 1993 was the British army. Thirty-eight active AH.Mk Is, with more in storage, remained in use with Nos 658 Sqn at Netheravon, 660 Sqn at Hong Kong and Brunei, and 666 Sqn (TA) at Middle Wallop.
Parallel development of the Wasp anti-submarine version took 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 powered by Nimbus turbine 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. Three aircraft performed take-off and landing trials from the escort vessel HMS Undaunted in November 1959.
Intended for ASW from frigates of the Tribal and Leander classes and similar vessels, 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).
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. Wasp deliveries began in 1963 after more than 200 test deck landings had been completed.
First Wasp HAS. Mk 1 for Royal Navy flew 28 October 1962, and entered service in October 1963. The 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). Two Australian Scouts were ordered in 1964 and delivered on 20 March 1963.
In the anti‑surface vessel role the Wasp is autonomous, and though it has no radar it can steer the AS.12 wire‑guided missile under visual conditions over ranges up to 8 km (5 miles). Outboard it can carry a Mk46 torpedo or two depth charges or one of each as well as underwater sound signal grenades, both smoke and flame marine markers and night illumination flares. For the utility role a winch is fitted as well as a cargo hook.
Duties include SAR (search and rescue), liaison, VIP ferrying, casualty evacuation with two internally carried stretchers, ice reconnaissance and photography/survey. The cockpit is equipped for bad‑weather operation with auto‑stabilization, radar altimeter, beacon receivers, UHF radio and UHF homer, and in RN service limited EW provisions. The quadricycle landing gear has wheels that castor so that, while the machine can be rotated on deck, it cannot roll in any direction even in a rough sea. Sprag (locking) brakes are fitted to arrest all movement.
The Wasp was replaced by the Lynx in the Royal Navy and Indonesia purchased ten second-hand aircraft from Holland (after refurbishment by Westland) when the latter's navy replaced its Wasp fleet with the Westland Lynx. The Royal Navy received a total of 98 Wasps; the last was retired in 1988.
Nine ships operated Wasps during the Falklands War of 1982. Wasp HAS. Mk Is operated from eight ships in that campaign, all assigned to RN No. 829 Squadron. They flew almost 1,000 hours in 912 combat sorties during which they made no fewer than 3,627 deck landings. Most were used in reconnaissance and utility missions, though several operated in the casevac role. Three, two from HMS Endurance and one from the frigate HMS Plymouth, engaged the Argentine submarine Santa Fe and holed its conning tower with AS.12 missiles. A Scout pilot won the Distinguished Flying Cross in tho Falklands for flying under fire to rescue a severely injured soldier. Wasps flew in support of British expeditions in Antarctica and the Empire Test Pilot School at Boscombe Down flew a Scout in their 'raspberry ripple' colour scheme.
Engine: 1 x Bristol Siddeley Nimbus 101 turboshaft, 530kW
Main rotor diameter: 9.83m
Length with rotors turning: 12.29m
Fuselage length: 9.24m
Max take-off weight: 2495kg
Empty weight: 1651kg
Max speed: 193km/h
Cruising speed: 177km/h
Rate of climb: 7.3m/s
Service ceiling: 3720m
Normal load: two Mk 44 torpedo
Engine: 1 x Rolls-Royce/Bristol Nimbus 103 or 104 turboshaft, 783kW
Maximum speed: 193km/h at sea level
Scout AH.Mk 1
Engine: 1 x 685 shp Rolls‑Royce Bristol Nimbus 101 or 102 turboshaft
Loaded weight: 2405kg
Empty weight: 1465kg
Max speed: 211km/h
Max cruising speed: 196km/h
Max rate of climb: 8.5m/s
Service ceiling: 4085m