The A300B aircraft is a co-operative effort by France, Germany, Great Britain, USA, Spain and the Netherlands. The work sharing regarding manufacture of the structure is as follows:

• MBB: Fuselage sections from the tail cone to section 16, upper shell of section 15, and the vertical tail.

• VFW-Fokker: Fuselage sections 13 and 14.

• AS: Flight compartment, fuselage sections 12, 15 (lower shell), wing centre box and pylons.

• CASA: Horizontal tail and passenger compartment door No 1.

• Fokker-VFW: Movable components on the wing, flap track fairings.

• British Aerospace (HSA): Cantilever wing, slats.

• General Electric: Engines.

• Messier: Landing gears.

The design of the A300B was based on many years’ experience gained on aircraft like the Trident (HSA) and the Caravelle (AS). Furthermore, by means of extensive studies and tests, bases were created to ensure reliability of the structure and to achieve an optimum design regarding weight and cost.

The initial phase of the design of an aircraft is usually thought of as being glamorous and exciting since it is the part of the total exercise which determines those characteristics of the aircraft for all to see. The artistically inclined can let his imagination run away with him as he visualises an aesthetically pleasing concept. The inventor has more than ample scope to propose layout innovations which supposedly confer some advantages, often of ill defined value. Tradition has it that the renowned designers of the past with their vast experience, aesthetic flair and innovatory streak would blend all the numerous possibilities into a satisfying if not always entirely satisfactory, project.

Of course such an idea is a gross over-simplification of the project design process which, as in any design activity, must consist of many configuration iterations before an acceptable solution is achieved. The large number of variables which have to be considered coupled with the extremely demanding performance and safety requirements of any advanced aeronautical system imply such complexity that every aid available must be employed.

One of the more important objectives of research in aerodynamics is drag reduction. In this paper we consider one part of the drag problem, the forebody pressure drag, and enquire about the lower limit to which it may theoretically be reduced by elimination of flow separation. It is customary to decompose the total drag force into two parts: pressure drag and friction drag, represented by force coefficients CD and CF, respectively. The ratio of these two forces may be taken as a convenient criterion to decide whether a body is ‘streamlined’ or ‘bluff’:

At high enough Reynolds numbers many bodies of interest are (according to this definition) bluff bodies, i.e. their pressure drag is much larger than the friction drag. This analysis is most relevant for bluff bodies where one needs to be concerned only with the pressure drag.

A method of improving the flow angle and Mach number distribution of a flexible-plate supersonic wind tunnel by small movements of the top and bottom liners has been known for a number of years. Once the influence on the flow, at a given Mach number, of small displacements of jacks supporting the liners are known, jack movements can be used to reduce non-uniformities in the working section flow. Such a procedure is being studied for adjusting the flow in the 8 ft x 8 ft Supersonic Wind Tunnel at RAE Bedford. However, one of the main difficulties encountered has been that of accurately determining the influence of each jack. The extended rippling in the plate which results from a displacement of a single jack generates a Mach number disturbance which is difficult to trace. This is particularly true at lower Mach numbers (i.e. near M=l.4) where the reflection of the disturbance from the opposite wall is observed to combine with the ‘tail’ of the direct effect, thereby causing interference effects in the data. Even with a 9-tube pitot rake spanning the tunnel it is difficult to ascertain which part of the disturbance is coming from the top of the tunnel and which part from the bottom. Ways have therefore been considered of moving the plate in the region of a particular jack in such a manner that the resulting waveform is shorter and more readily traced. A simple but effective system of jack movement has been derived and is described here as the 1-4-1 system.