Helicopter handling qualities in degraded visual environments

• Main Author: Clark, Gary A.
• Published: University of Liverpool 2007
• Subjects: 629.13
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486093

New generation military helicopters are required to fly Nap-of-the-Earth (NoE) roles at night and in poor weather conditions. In these situations the pilot must guide the aircraft through obstacle cluttered environments, retain sufficient stabilised ' control, while at the same time coping with a range of degraded visual conditions. The Useable Cue Environment (UCE) procedures provide a means of assessing handling qualities as a function of available visual information, subsequently suggesting minimum control requirements (Response Types) in order to aid the pilot with the stabilisation of the aircraft. While the UCE procedures are' the preferred industry standard for quantifying and maintaining good levels of handling qualities in DVE, there is no direct appreciation of the difficulties encountered with guiding the aircraft or avoiding obstacles. The aim of this study was to develop the UCE approach by incorporating the guidance function of piloting, subsequently enriching the 'Helicopter Handling Qualities in Degraded Visual Environments' analysis procedures. To date few investigations have taken place to determine how the pilot guides the aircraft at low level and through cluttered environments. Recent studies in this field, involving the University of Liverpool, have suggested the importance of the movement of objects and textures in the visual scene (optical flow) for such prospective flight control. The most recent incarnation of this theory introduces the importance of a parameter called tau, ' , a natural temporal means of control thought to be exercised by animals and humans. '-theory provided a starting point for this investigation, developing into a series of piloted simulation trials to examine guidance based manoeuvring. Using a few carefully selected visual degradations, this extensive simulation campaign helped to identify the important visual information for guidance, such as the visual flow quality and the temporal range through which the pilot can see in order to plan his way through a cluttered environment. These findings have been translated into new UCE limits and overlaid onto the existing UCE chart. Added to these handling qualities prediction methods, a pilot control strategy for performing each of the manoeuvres has been developed using the principles of ' coupling. The possible use of this ,,-based control has been explained through the conceptual design of a tunnel-in-the-sky type flight director.