No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Possible helicopter flight mechanics benefits associated with the use of an actively controlled horizontal tailplane are identified, influencing the areas of agility and manoeuvrability. In both cases, control strategies are postulated and implemented by means of control laws. They are then used with mathematical descriptions of the helicopter in digital computer simulations of manoeuvres to quantitfy the benefits. In the field of helicopter agility, use of a relatively small horizontal tailplane is shown to enhance agility, relative to the helicopter with a fixed tailplane. Popup maneouvres to SOm can be flown up to 7% faster with the active tailplane; alternatively, geometrically tighter manoeuvres can be flown to the extent of reducing manoeuvre distance by up to 10%. The control law moves the tailplane proportionally with the contributions of the three rotor controls and helicopter pitch rate to the longtitudinal component of hub moment. It is however suggested that a tailplane control law based on functions of pitch attitude would be applicable to a wider range of manoeuvres than the popups simulated. Helicopter manoeuvrability is enhanced by using the tailplane to decouple the pitch attitude from the flight path. The benefits are demonstrated by simulation of the acquisition and tracking of an airborne target. For a helicopter with the conventional pattern of control, significant changes in flight path result when the target is tracked with fuselage pointing; by comparison, the helicopter with a decoupled flight path and attitude controller changes flight path and speed by a negligible amount. It is suggested that this mode of control may be more generally applicable to control of the helicopter in that it mitigates the speed/flight path/attitude compromise the pilot faces in flying his aircraft, or the possibly large hub moments when accelerating or decellerating. The philosophy behind the use of the active tailplane differs from that of contemporary applications of moveable tailplanes in that it is an integrated element of the flight control system endowing (in its own right) control capabilities on the helicopter that are otherwise precluded by configuration. The addition of this extra control demands active control technology for several reasons: the applications require full control authority; the control laws are multivariable and change with speed; and the cockpit control setup would have to be simplified to the extent of the radical changes facilitated by active control technology.

This thesis considers the placement of two or more Unmanned Aerial Vehicles (UAVs) to provide communications to a community of ground mobiles. The locations for the UAVs are decided by the outcome of a non-cooperative game in which the UAVs compete to maximize their coverage of the mobiles. The game allows navigation decisions to be made onboard the UAVs with the effect of increasing coverage, reducing the need for a central planning function, and increasing the autonomy of the UAVs. A non-cooperative game that includes the key system elements is defined and simulated. The thesis compares methods for solving the game to evaluate their performance. A conflict between the quality of the solution and the time required to obtain that solution is identified and explored. It considers how the payload calculations could be used to modify the behaviour of the UAVs, and the sensitivity of the game to resource limitations such as RF power and radio spectrum. It finishes by addressing how the game could be scaled from two UAVs to many UAVs, and the constraints imposed by current methods for solving games.

The introduction of fly-by-wire electronic flight control systems into transport aircraft has given the flying qualities engineer the opportunity to optimise the flying qualities of these aircraft for their specific tasks. With this technology has come the opportunity to introduce new technologies into the cockpit, such as non-linked or backfed sidesticks and non-backfed throttle levers. A comparative survey of airline pilots flying such a very high technology unconventional aircraft and a high technology but conventional aircraft suggests that these technologies may reduce the available channels of communication to the pilot in the very high technology aircraft, resulting in the possibility of reduced situational awareness. A closed loop piloted simulation survey of ten transport aircraft in current operation was undertaken which demonstrated that they all suffered from flying qualities deficiencies, limiting the performance that the pilot could achieve. In particular poor dynamics precluded the pilot adopting tight closed loop, or compensatory, control. Instead it was necessary to adopt a more open loop, precognitive, technique with medium frequency modulation, resulting in a degradation in landing performance. Through appropriate flight control system design it should be possible to produce aircraft that can be flown using the full range of control inputs from open to closed loop. The major study of this thesis assessed, through piloted simulation evaluations, the suitability of a wide range of longitudinal commanded response types for the approach and landing tasks. It was concluded that a response type that closely resembles that of angle of attack is optimum for these tasks due to its conventional characteristics of speed stability on the approach and monotonic stick forces in the flare. Such a system, appropriately implemented, should allow the transport aircraft pilot the full range of piloted control inputs, from open loop, precognitive, to closed loop, compensatory, resulting in improved landing performance.