This paper deals with control of V/STOL aircraft in powered-lift flight. A review of representative operational mission tasks is presented for the take-off, transition, hover and landing flight phases. Characteristics inherent in the basic airframe and propulsion system and the behaviour associated with control augmentation systems are considered. Demands for augmented stability and control response to meet certain mission operational requirements are discussed. Experience from ground-based simulation and flight experiments that illustrates the impact of augmented stability and control on aircraft design is related by example.

A method to calculate two-dimensional or axisymmetric, compressible, wall-bounded viscous flows is described. The solution procedure involves a finite-difference discretisation of the governing flow equations. A number of novel normal co-ordinate transformations are used to enable efficient use to be made of the computational grid points. The implementation of zero-, one- and two-equation turbulence models is described. Results are presented for a range of compressible boundary-layer flows, and for an incompressible wake/ boundary layer mixing flow.

An experimental investigation has been performed to study the formation and development of spiral vortex flow over a swept-back wing. An aerofoil section with three alternative leading edge shapes was tested at sweep angles ranging from 0° to 56° for unit Reynolds numbers of 1 × 106/m and 2 × 106/m. The principal diagnostic tool was the surface oil-flow visualisation technique supplemented by pressure distribution measurements in certain cases. No spiral vortex flow was observed for sweep angles of 0° and 15° but at higher sweep angles the oil-flows indicated that there were three different mechanisms for the formation of spiral vortices. The angle of incidence at the onset of vortex flow, and the mechanism responsible for its formation, were found to depend upon the sweep angle, the leading edge shape and the Reynolds number. It was also noted that the larger the leading edge radius the greater the dependence upon Reynolds number. However, comparison with other work suggests that Reynolds number, incidence and sweep angle alone are insufficient to determine the type of spiral vortex flow occurring on a given wing.