Saro P.531

P.531
First P.531-0, G-APNV at the Farnborough show 1958
Role	Five-seat utility helicopter
Manufacturer	Saunders-Roe
First flight	20 July 1958
Introduction	1959
Primary user	Fleet Air Arm
Number built	6
Variants	Westland Scout Westland Wasp

The Saro P.531 (or Saunders-Roe P.531) is a British all-metal five-seat helicopter designed and built by Saunders-Roe Limited (Saro).

Design of the P.531 was started in November 1957 as a private venture improvement of the company's earlier Skeeter. The first prototypes were powered by a derated 325 shp Blackburn Turbomeca Turmo 600, a free turbine engine allowing clutchless transmission. The P.531 first flew on the 20 July 1958. Three more developed P.531-0s followed and these were delivered to the Royal Navy/Fleet Air Arm for trials and familiarisation. Following evaluation by the Navy a batch of 30 developed aircraft were eventually ordered as the Westland Wasp.

Two militiarised P.531-2s were completed in 1959, powered by the Blackburn Nimbus and the de Havilland Gnome H1000 free-turbine engines, both derated to 635 hp now that the transmission tests had proved such powers acceptable. Like the Turmo installation, these engines were mounted, uncowled behind the cabin for easy servicing. There were aerodynamic shape revisions and a floor extension to allow six, rather than five seats. The vision was improved with perspex panels in the doors, tankage was increased and all-metal rotors introduced. These modifications increased gross weight by 1,200 lb (544 kg).

Saro had an order for eight pre-production aircraft from the Army Air Corps for evaluation and trials; these would have been known as the Saro Sprite, but the company was taken over by Westland and the aircraft became the first Scout A.H.1s.

Another P.531-2 was built for evaluation by the Indian government but following a lack of interest was re-worked as Scout standard for the Army Air Corps.

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General characteristics

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