Westland Scout - Design and Development

Design and Development

Both the Scout and the Wasp were developed from the Saunders-Roe P.531, itself a development of the Saunders-Roe Skeeter. With the acquisition of Saunders Roe, Westland took over the P.531 project, which became the prototype for the Scout (originally called Sprite) and the Wasp.

The P.531 was developed with the 635 shp (474 kW) Bristol Siddeley Nimbus and the 685 shp (511 kW) de Havilland Gnome H.1000 engine, which flew from 3 May 1960. The production Scout AH.1 used a 1,050 shp (780 kW) Rolls-Royce (RR having acquired Bristol Siddeley by then) Nimbus 101 engine, torque limited to 685 shp (511 kW), and achieved its first flight on 29 August 1960. The Nimbus power ratings were 1,050 shp (780 kW) for five minutes, 685 shp (511 kW) for one hour and 650 shp (480 kW) could be maintained up to 7,000 ft (2,100 m) at 30 degrees Celsius.

The Scout has a rigid tubular skid undercarriage with two oleos connecting the rear cross-tube to the fuel tank rear bulkhead. Despite appearances the oleos act in tension, not compression, damping the reflex action to prevent the aircraft bouncing and ground resonance when landing. Energy absorption on landing is mainly through the two cross-tubes. Additional rigidity is given to the undercarriage through diagonal struts connecting the rear cross tube to the main fuselage longitudinal webs. These struts also help stiffen the airframe vertically and laterally, and are fitted with quick release pins to allow access to the fuselage access panels. The rear cross-tube is anchored centrally and the front cross-tube is fixed to the two main fuselage longitudinal webs. The port skid also acted as a storage tube for the long HF aerial, the skid was accessed via a screw-fixed cap at the rear. The vertical spigot at the front of each skid is used to mount ballast weights to alter the aircraft's centre of gravity.

Behind the two front seats was a three-seat bench, although this could be replaced with a four-seat bench when fitted with modified rear doors (see main photograph). It was used for general light work including observation, liaison, training, and search and rescue. When fitted as a light attack helicopter it carried either two, skid-mounted, forward-firing machine gun (L8A1 GPMG) packs or a single pintle mounted machine gun in the rear cabin. The pintle mount was available in both port and staboard mountings. The gun-packs, which were both aimed at a pre-set convergence angle, carried 200 rounds of ammunition and were mounted on a tubular spar that was fixed between the front and rear undercarriage legs. In the anti-tank role it could carry four guided missiles (the Nord SS.11). The sighting unit was the AF.120, the result of a joint venture between Avimo and Ferranti and had x2.5 and x10 magnification. The APX Bezu sight unit was also evaluated but rejected, although it was adopted for use on the Westland Wasp. Additional testing and trials were carried out with the Hawkswing(initially known as Airstrike Swingfire) missile. Initial firings were carried out in early 1972, to test the system for the Westland Lynx, the associated AF.530 sight was subsequntly trialled in 1974. The Hawkswing system was cancelled in 1975 due to its manual control system (MCLOS) compared to the semi-automatic (SACLOS) system utilised by its rivals HOT and TOW. In the casualty evacuation role (CASEVAC), the Scout could carry two stretchers internally or two on externally mounted pods, the co-pilots seat could also be reversed to allow an attendant to face the casualties.

Although the general design of the aircraft was robust, with an airframe fatigue life of 7200 hours, the cockpit ergonomics were less than perfect. An example of this was the cabin heater switch being mounted next to the fuel cock. Unfortunately this led to the loss of at least four aircraft when the pilot misadvertantly closed the fuel cock instead of switching off the cabin heater, causing the engine to shut down. The autorotational qualities of the Scout have also been described by some pilots as 'startling'. In service trials and testing were carried out by the AAC's Development Wing at Middle Wallop, Hampshire. A wide variety of weapons and equipment were evaluated, although many were never adopted. Amongst these were the 7.62mm General Electric Minigun and the two inch rocket pod. The rocket pods were mounted either side of the central fuselage section on the multi-spar weapon booms and both smooth tube and fin-stabilised rockets were tested, although the accuracy was described as 'indifferent'. Studies were also carried out for a pintle mounted M2 Browning machine gun in place of the standard 7.62 GPMG, and the French AME.621 20mm cannon. Another was the installation of a Bendix R.100 lightweight weather and ground-mapping radar, which had a range of eight and forty miles. This was mounted behind the fibreglass nose access panel along with a small viewing screen in the cockpit. The radar antenna was moved further forward later in the development and a small, pronounced nose cone was fitted onto the panel.

During the development of the WG.13 Westland Lynx, two Scouts were used as testbeds and fitted with full-scale, semi-rigid Lynx main rotor heads, despite the fact that the WG.13 rotor diameter was greater by around three metres. The first test flight was achieved 31 August 1970. A prototype MBB BO 105 also used a Scout main rotor head and blades during the development phase, unfortunately this aircraft was destroyed due to ground resonance during its initial trials.

About 150 Scouts were built through 1968, primarily at the Fairey Aviation Division factory at Hayes.