Prediction and Assessment of Aircraft/Rotorcraft Pilot Coupling Phenomena

Principle Investigator: Prof. G.D. Padfield; Research Associate: Mr. M. Jump. Funding body: Engineering and Physical Sciences Research Council (EPSRC), standard research grant EP/D003512/1.

Definition: Adverse Pilot Coupling (APC): "APC events are fundamentally interactive and occur during highly demanding tasks when environmental, pilot, or aircraft dynamic changes create or trigger mismatches between actual and expected aircraft responses" [1]

The description by the Wright Brothers of their first and subsequent powered flights suggests that they experienced pitch oscillations of a pilot-induced nature [2]. The reconstruction of the flights of the Wight Brothers’ aircraft in piloted simulation at Liverpool has also demonstrated their strong propensity to this particular form of adverse pilot coupling – the pilot induced or involved oscillation (PIO) [3, 4]. PIO events or more generally, APC events have been observed and occasionally publicly documented ever since. The advent of aircraft with highly augmented control systems has not brought about an end to these phenomena and has been the subject of international attention [5]. However, even one of the most up-to-date analyses and reviews of the topic [1] devotes only 4 out of 208 pages to APC phenomena in rotorcraft. This is despite rotorcraft having limited stability, low values of response bandwidth and a propensity for coupling between rigid body and rotor/fuselage aeroelastic modes – all ingredients of an APC-prone vehicle. This project has therefore been established to try to answer the following research questions:

1. What are the fundamental mechanisms that contribute to rotorcraft APCs within the pilot, aircraft and task environment ?

2. How can APCs be described and predicted through modelling and simulation ?

3. What options exist for including APC considerations within rotorcraft design and testing procedures ?