Fifty years ago, the A.V. Roe Team took the Lancaster four engined bomber (Fig. 1) from concept to first flight in a period of about nine months. Under the driving pressures of War and with an outstanding approach to the challenges of the project, a number of key concepts emerged, which are still considered modern and innovative today:

1. Teamworking and leadership

2. Design for ease of production

3. Simultaneous engineering

4. Materials and parts supply logistics

This approach considered the aircraft engineering process as a whole and kept the ultimate aims of the project uppermost.

The project achieved remarkable manufacturing performance targets; assembly of 49 aircraft per week at peak production, combined with a three and a half day assembly lead time.

After the War, the need to manufacture aircraft in large volumes decreased and at the same time rapid technical advancements dramatically increased aircraft complexity. The nature of the industry changed and the balanced application of design engineering and manufacturing logistics that had made Lancaster manufacture so successful, became of secondary importance. During the 1970s and 1980s improvements in manufacturing within the aerospace industry were fragmented and now, at the beginning of 1990s, when the UK aerospace industry is compared with other sophisticated, high-technology industries, most business performance indicators are firmly at the bottom of the league (Fig. 2).

The flow-fields associated with single and twin jets impinging in cross-flows have been studied. Parameters which affect the position of the ground vortex have been investigated: cross-flow-to-nozzle velocity ratio, cross-flow boundary layer thickness, nozzle height, nozzle pressure ratio, vector angle and nozzle splay with both fixed and moving ground planes. Results show that the ground vortex moves away from the nozzle centre-line as the ratio of cross-flow velocity to nozzle exit velocity is decreased; the rate of change of position, however, depends on other parameters (including the precise definition of nozzle exit velocity). Increasing nozzle height above the ground appears to cause little consistent variation in vortex position for a single jet but a marked forward movement of ground sheet separation point in the case of twin jets. For all cases there is an increase in penetration with increasing nozzle pressure ratio up to choking, with the subsequent behaviour dependent on the definition of nozzle equivalent velocity and cross-flow velocity ratio. The effect of the moving ground plane is to reduce vortex penetration significantly; this suggests that a moving ground plane simulation (or moving model) is essential when testing design configurations in ground effect in wind-tunnels. It is also shown that rig design can produce a blockage effect which moves the ground vortex significantly and can change other apparent parametric effects. Self-similarity laws are proposed for the ground vortex and the wall jet.

A simple flow model has been developed to predict the size of the separation bubble which forms at the sharp leading edge of a flat plate aerofoil at incidence a which are less than about 8°, and the corresponding lift and drag coefficients. This flow model is based on irrotational flow and source singularities which are determined indirectly from experiment. The bubble length is shown to be proportional to α2with a slope which depends on the rate of growth of the separated shear layer. A thin double-wedge aerofoil has been tested in a wind tunnel. It is concluded that these and previous measurements agree fairly well with the theory for chord Reynolds numbers greater than about 0.5 × 106.