European Aero Engine Companies assisted by National Research Establishments have a long and successful record in the design, development and manufacture of engines for high performance military fighter aircraft.

Because the cost of developing and producing a new aero engine is now so great, it has become increasingly impracticable for individual European nations to embark on such projects alone. This has resulted in recent years in a number of collaborative European engine programmes. As Fig. 1 shows, the range of European military turbofan engines now in service is largely the result of such collaboration amongst various European countries, and compares with the much more limited US involvement in design collaboration. Figure 1 also shows that the thrust range covered by European military turbofans is very comparable to that of engines of US manufacture.

Small gas turbine engines are used in a large variety of applications (Fig. 1) and therefore any model range should accommodate as many of these roles as possible to secure a broad market base. First and second generation engines were launched initially against a requirement for military helicopters and small to medium sized turboprop powered aircraft. However due to the search for oil the role of the helicopter has expanded into offshore oil exploration whilst the better fuel efficiency of the turboprop powered aircraft relative to the turbofan will ensure its future for short range commuter aircraft. Additionally with further improvements in helicopter and engine reliability and costs, the helicopter will be used increasingly in the Air Taxi role to provide rapid transportation over short distances to avoid ground traffic congestion or particular geographical features that preclude short transit times. Specifically the use of the helicopter to connect airports with each other and city centres is becoming a real possibility as reliability improves and operational costs reduce.

In this presentation I will review the advances in manufacturing technology applied to the manufacture of large civil aero engines, but first I think we ought to look back and put these advances into some sort of historical perspective.

Traditionally the level of automation in civil aero engine manufacture has been relatively low. However, the level of technology in the component and that applied to the individual manufacturing operations has been very high.

Automation, from the start of the Industrial Revolution has been directed to the mass production of high volumes of relatively simple stable design components using conventional materials and production processes.

Time-dependent aerodynamics is primarily concerned with the pressure distributions developed by moving control surfaces, such as the oscillation of a trailing-edge flap, the rapid extension of a spoiler, or the pitching of a canard.

Some recent experiments in time-dependent aerodynamics are reviewed. These include wind tunnel dynamic interference and its attenuation, the aerodynamics of an oscillating trailing-edge flap, the reduction of response to turbulence by active control, the aerodynamic characteristics of rapidly moving spoilers, and the time-dependent aerodynamic characteristics of supercritical wings.

The paper concludes with a discussion of aeroelastic problems at subsonic and transonic speeds and with some buffeting measurements in a cryogenic wind tunnel.

A duct design algorithm is presented by which duct wall shapes are produced directly from prescribed wall friction velocity distributions. The method is based on matched axisymmetric core flow and integral boundary layer solutions in which the flow is assumed to be in viscid in the core, turbulent in the boundary layer and incompressible throughout. An inverse boundary layer analysis is based on Coles profiles coupled with momentum and entrainment equations. Wall friction velocity is used as the major boundary condition which leads to the calculation of the required core velocity at the boundary layer edge. This velocity distribution is simultaneously employed as the major boundary condition in an inverse core flow calculation which is based on an inverted form of the Stokes-Beltrami equation. The displacement surface method is used to match boundary layer and core solutions which together lead to a predicted duct shape. Numerical results are presented, some of which include separated boundary layer flows. An assessment of the influence of wall friction velocity distribution on duct shape and wall pressure field is included.