PROGRESS IN THE DEVELOPMENT OF COMPLEMENTARY HANDLING AND LOADING METRICS FOR ADS-33 MANOEUVRES

The aim of the present paper is to present a novel approach to handling qualities investigations by developing and testing new complementary metrics capable of being applied to both agility and structural loads analysis. Two questions are to be addressed: 1) how can one extend existing ADS-33 metrics to ones pertaining to both agility and vibratory loading analysis? 2) how can one extend and/or interrelate the current helicopter metrics to handling metrics originating from fixed-wing aircraft? Concerning the first question, the present paper focuses on two new metrics relevant to manoeuvring in forward flight: the agility quickness and the vibratory load quickness. While the agility quickness characterises the helicopter performance, the load quickness could be used to quantify the build up of loads in the airframe. For the agility metric the present paper proposes quality boundaries based on the performance standards during aggressive manoeuvring (high yo-yo, transient turns and pull-up manoeuvres). The trends in the load quickness are also presented and shown to increase with manoeuvre amplitude, where the designer would prefer them to decrease. Concerning the second question, the paper looks at how the control anticipation parameter (CAP) might be applicable to rotorcraft handling qualities investigations. It is demonstrated that while CAP could be used as a metric to correlate the flight path response with the attitude response for small-amplitude manoeuvres, agility quickness is a more logical extension of ADS-33 to account for more aggressive manoeuvring in forward flight. CAP charts are plotted for helicopter and Tiltrotor examples and then interpreted as a measure of quickness in highly agile manoeuvres. It is concluded that this novel approach could be particularly useful to Tiltrotor applications where the handling qualities in fixed-wing mode and in helicopter mode must merge together within new criteria.