The notion of airplane stability and control being a balancing act between
stability and control has been around as long as aeronautics. The Wright
brothers’ first successful flights were born of the debate, and were successful at
least in part because they spent considerable time teaching themselves how to
control their otherwise unstable airplane.
This thesis covers four aspects of handling for large transport aircraft: large
size and the accompanying low frequency dynamics, the way in which lifting
surfaces and control system elements are modelled in flight dynamics analyses,
the cockpit feel characteristics and details of how pilots interact with them, and
the dynamic instability associated with Pilot Induced Oscillations.
The dynamics associated with large transport aircraft are reviewed from the
perspective of pilot-in-the-loop handling qualities, including the effects of
relaxing static stability in pursuit of performance. Areas in which current design
requirements are incomplete are highlighted. Issues with modelling of dynamic
elements which are between the pilot’s fingers and the airplane response are
illuminated and recommendations are made.
Cockpit feel characteristics are examined in detail, in particular, the nonlinear
elements of friction and breakout forces. Three piloted simulation experiments
are described and the results reviewed. Each was very different in nature, and
all were designed to evaluate linear and nonlinear elements of the cockpit feel
characteristics from the pilot’s point of view. These included understanding the
pilot’s ability to precisely control the manipulator itself, the pilot’s ability to
command the flight path, and neuro-muscular modelling to gain a deeper
understanding of the range of characteristics pilots can adapt to and why.
Based on the data collected and analyzed, conclusions are drawn and
recommendations are made. Finally, a novel and unique PIO prediction criterion is developed, which is based
on control-theoretic constructs. This criterion identifies unique signatures in the
dynamic response of the airplane to predict the onset of instability
