A survey of the Messerschmitt-Bolkow-Blohm company's activities in the helicopter field amounts to a review of the past 15 years. The scope of these activities, as measured by their technical diversity, can only be appreciated in full if something is known of the progressive thinking involved, the company's courage in taking commercial risks and the development and contract situation in post-war Germany.

The Bolkow company evolved from a small engineering office into an aeronautical company in 1955, and from this time on the development of rotary wing systems was one of its important development aims.

The subject of management techniques needs to cover a wider field than the rather narrow interpretation given in much current discussion of its tools. To cover the relevant area, it is intended to use the managerial concepts pioneered by the Frenchman—Henri Fayol. Fayol suggested management activity is made up of five parts:

• Planning

• Organising

• Commanding

• Co-ordinating

• Controlling

The machinery used for the management of the development of the Sea Dart missile will be reviewed under those five parts.

Rapier is a very important element in our armoury of defence against attack from the air. At low to medium altitudes the attack comes from all-weather, contour-following, very fast and very expensive aircraft, through much more numerous and diverse conventional aircraft limited to fair-weather operation, to helicopters and reconnaissance drones.

The perfection of radar makes the high open sky a dangerous place to be. Aircraft are best used, like any other weapon, when they enjoy the greatest advantage. They will therefore, fly high enough to see their objective (stationary or slow-moving targets) but low enough to gain concealment from radar surveillance.

Part I (ref. 1) explained the ideas underlying Cheeseman's circulation-controlled rotor proposals and described the wind tunnel experiments on circular sections equipped with circulation control slots. The present paper describes the model rotor built and tested at the National Gas Turbine Establishment. Its hovering performance is fully analysed using the sectional performance correlation of Part I.