In the past, new concepts have largely stemmed from the use of intuitive techniques by original thinkers. These approaches, though still useful, are now reinforced by more powerful, formal, and systematic, methods of examining the possible patterns for the future. These methods are part of the process of technological forecasting and are described in references.

The results of the forecasting process may then be assessed and evaluated using further methods of operational research such as cost effectiveness analysis.

The approach and landing of a transport aircraft is a complex operation over which the pilot has only limited control. Although the efficiency of the crew and the serviceability of the aircraft and its systems are to a considerable extent within the command of the pilot, the standards of air traffic control, the availability of navigational aids and the runway length and lighting are beyond his immediate influence. Letdowns with imperfect air traffic control and limited precision aids, particularly if complicated by adverse meteorological conditions, lead to very high workloads which the pilot may find difficult to assimilate. Under these circumstances difficulties may arise during the approach and landing.

In recent years many investigations have been made into ways of reducing the pressure jumps across the shock waves resulting from supersonic transports. Lately Warren has stated that a quantity which typifies a sonic bang and in particular with regard to its effect on structures is the characteristic overpressure. The characteristic overpressure is the ratio of four times the running integral of the overpressure to the time interval between the first and last shock in the signature. The work on the pressure jumps across the shock waves and the resulting lower bound values have to be modified when the characteristic overpressure is considered. This note describes a preliminary investigation into methods of obtaining the lower bound values for the characteristic overpressure.

The design of a vehicle with cruise capability which can be packaged in a volume limited space, such as a cylindrical tube, centres around the problem of folding the lifting and control surfaces in such a manner that their deployment is simple and reliable. Several folding schemes are illustrated in Fig. 1. A wing fabricated of a flexible material and suspended by lines from the fuselage (parawing, Fig. 1a) can be folded to occupy only a small volume. These wings, however, are difficult to deploy at high forward speeds and have characteristically poor lift/ drag ratios unsuitable for high performance cruise capability. Another concept which allows storing the wing in a volume-limited space is the “scissor” wing (Fig. 1b) which, when deployed, swings out from a cavity in the fuselage.

The problem of a delta wing in a high speed stream has been approached using linearised potential flow theory for low supersonic Mach number, and using thin shock layer theory for hypersonic Mach number. Recently the author has given a new theory of supersonic and hypersonic flows with attached shock wave over the compression surface of an unyawed delta wing. It has the advantage of being unified for both supersonic and hypersonic flows, and it gives almost identical results compared with exact numerical solutions. The purpose of this note is to extend the theory of Ref. 4 to include the effects of yaw.

The possibility of failure by buckling of structural members subjected to compressive loadings concerns every structural engineer and designer. In the design of aircraft, these compression members may be stringers, spars, or other stiffeners. Various geometrical sizes and shapes of stiffeners are used in aircraft construction. They are either extruded in the desired shape, machined, or formed out of sheet metal on a hand brake. They may be I-beams, Z-beams, channels, or angles. They may be used singly or may be joined to form a built-up or composite member. The actual choice of the size and shape of the stiffener depends upon the forces and moments to which it will be subjected.

In view of the increasing awareness of the population to noise pollution, reduction of aircraft noise annoyance to an acceptable level becomes one of the necessary conditions for the acceptability of aircraft operations close to populated areas. In particular, reducing the subjective acoustical annoyance of VTOL aircraft to the surrounding community should become the common objective of aircraft manufacturers, airport planners, potential aircraft operators and the community itself if the latter is to benefit from all the possible advantages of VTOL service.