The development of the P.531 family of helicopters covering the period of approximately 5 years is presented. Evolution from the first basic aircraft towards a land-based general purpose helicopter, the Scout, and towards a shipborne helicopter operating from small ships, the Wasp, is presented. The basic design features of the Scout are described briefly as broadly representative of the family. Development experiences are reviewed under the following main headings:—

• (i) Ground resonance investigations.

• (ii) Development of satisfactory flight handling characteristics including engine/rotor control system

• (iii) Substantiation of structural integrity,

• (iv) Development of systems and operational equipments.

• (v) Environmental and climatic testing.

Development of miniaturised auto-stabilisation/autopilot system, for small helicopters, considered to be an important programme, is briefly reviewed. More detailed consideration is given to operations from small ships. The possible design solutions to ensure satisfactory operation from small ships are briefly reviewed, and the reasons for the solution chosen for the Wasp, i.e. four wheel undercarriage are given. Development experiences with the preferred solution are briefly described. It is shown that for operation from small ships in the Naval application a fair degree of complexity is unavoidable independent of the size of a helicopter.

Some statistical data on the development efforts expended are given and some tentative conclusions drawn, aiming at determination of the necessary conditions which would promote a relatively speedy development of a new helicopter.