The arrival on the aeronautical scene of a new generation of propeller driven commercial aircraft, and the great interest in the propeller as an economical means of propulsion for high subsonic Mach numbers, makes this an appropriate time to look back and attempt to identify some of the evolutionary paths by which the present state of development has been reached.

A consideration of the history of the propeller may be confined to the period beginning around the late eighteenth and early nineteenth century, when the propeller was clearly recognisable as such and becoming established. However, the idea goes back many centuries before this and there is a wealth of references describing, not always very precisely, various mechanical devices intended or actually used for ship propulsion which may be considered remote but legitimate ancestors of the present day propeller. Before considering more recent developments, it is worth looking at the beginnings of mechanical propulsion if only to pay tribute to those early engineers who did not allow the lack of suitable materials or theory to inhibit their attempts.

Digital data transmission techniques enable various elements within a system to communicate in an efficient manner. Multiplexing techniques permit this data to be transferred rapidly, accurately and reliably, without the constraints imposed by conventional wiring systems which employ heavy and costly cable runs and expensive connectors. In today’s cost conscious aviation world, both military and civil users are anxious to capitalise upon savings in cost and weight while gaining substantial benefits in terms of performance and reliability.

Smiths Industries has been involved for over a decade in the application of multiplexed data transmission systems. The military Tornado serial data transmission system and the civil ARINC data transmission systems are areas where specific expertise has been established. More recently the weapon systems unit of the company’s Cheltenham Division together with Micro Circuit Engineering, an SI subsidiary, has established a world lead in the development and the application of the widely accepted data bus standard, MIL-STD-1553B.

The role of the International Civil Aviation Organisation (ICAO) in developing standards and recommended practices for communication, navigation and surveillance systems is well known. The emphasis is on system characteristics and the definition of airborne equipment is limited to essential characteristics. For many years, the world’s airlines have collaborated in the Airline Electronic Engineering Committee of ARINC to produce engineering characteristics to ensure interchangeability and hence freedom of choice in their selection of airborne equipments. Thus ‘box’ dimensions, types and pin connection, interfaces cabling, coding etc are covered.

For the electronics industry designing equipment to meet the needs of both the aircraft constructors and their customers, the airlines and the Airworthiness Authorities responsible for the certification of equipment installed in passenger carrying aircraft more detailed specifications are essential. This problem was recognised in the USA and a solution was found in the formation of the Radio Technical Commission for Aeronautics (RTCA). With the direct support and involvement of USA Government Departments, the Electronics and Aircraft Construction Industry, the Airlines and General Aviation operating as ‘Special Committees’ of experts, RTCA developed Minimum Performance Standards. These documents are used by the FAA as the basis for equipment certification.

More than ten years of development have gone into the Rolls-Royce wide-chord fan, which will provide a 2½ per cent fuel saving when it enters service in 1984. This new and highly efficient fan is one of the advanced features of the 535E4 engine, which will have a fuel consumption 10 per cent better than that of the initial Rolls-Royce engine for the Boeing 757, the 535C.

How has this advanced fan been developed and what are its advantages? This article surveys the reasons for its development and the factors involved in this technical advance pioneered by Rolls-Royce.

Previous analysis of the operation of the counterspun nutation damper has been restricted to small nutation angles and to axisymmetric spacecraft. This paper develops equations for the dynamics of nutation damper/spacecraft combinations in which the spacecraft is non-axisymmetric and may adopt large nutation angles. In addition, a mechanism to model the growth of nutation due to energy dissipative mechanisms on board the spacecraft is introduced.

The dynamic equations were programmed in a digital simulation language. The effects of three probable imperfections in the construction and operation of nutation dampers on the operating characteristics of the dampers were investigated by simulation. The implications of these non-ideal conditions for the design of counterspun nutation dampers are identified.