Abstract:
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.
