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 400shp Turmo 603 shaft turbines, derated to 325shp.
Saunders-Roe P.531 G-APNU
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. 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. Subsequently developing the P.531 as the Scout AH.Mk 1 for the British Army and Wasp HAS.Mk 1 for the Royal Navy.
Engine: Blackburn A.129 free-turbine