Capturing requirements for tiltrotor handling qualities – case studies in virtual engineering

Abstract

Handling qualities are expressed as requirements at the interface of the pilot and the machine. In this way, the key functionality questions facing the design engineer are seen from the perspective of the interaction of the human pilot with the aircraft system and the environment in which it operates. In this paper, the author takes a ‘virtual engineering’ approach to handling qualities, emphasising the importance of conducting ‘requirements capture’ and preliminary design as an iterative process. When stretched capabilities are required, this approach minimises the risk to finding appropriate technology solutions, through developing explicit relationships between capability and design parameters, thus facilitating fully informed trade studies and predictions. Case studies from the development of a civil tiltrotor aircraft are presented that show how the difficult challenges facing the designer first need to be structured in terms of HQ predictions and assignments. This then provides the basis on which handling qualities improvements can be constructed within the multidisciplinary context of rotorcraft engineering.

Rotorcraft Design for Maximized Performance at Minimized Vibratory Loads

“…The emphasis of the chapter will be on agility characteristics in the pitch axis applied to helicopter and tiltrotor. Especially in such new configurations, the proposed approach could be particularly useful as the performance tools for fixed-wing mode and helicopter mode must merge together within new criteria (Padfield, 2008). The chapter is structured as follows: The second section will present an overview of traditional metrics for measuring pitch agility; The third section will present some alternative metrics proposed in the 90's for better capturing the transient characteristics of the agility; Then, based on the rational developments of the metrics from the previous two sections, fourth section will propose the new approach that can better quantify the agility from the designer point of view.…”

“…In the last twenty years, however, ever-increasing performance requirements and extended flight envelopes were defined, for reasons of heavy competition, demanding manoeuvres that impose heavy vibrations on both structure and pilot. These vibrations, combined with cross-coupling effects, rapidly lead to pilot overload and degradation in performance (Padfield, 2007). Key Problem: The current practice of assessing rotorcraft handling qualities reveals significant gaps in the ADS-33 HQ criteria, especially regarding the effects of vibrations.…”

Handling Qualities in Rotorcraft Conceptual Design

“…One reason for HQs' evaluation not having been taken into account during the conceptual design stage in previous experiences is related to them being interwound to the pilot's behavior and perception [27,31]. Understanding and quantifying the desirable dynamic response of an aircraft from the pilot's perspective culminated in the development of the ADS-33 design standard [1], which represented a crucial step towards making use of HQs' ratings from an engineering point of view [32].…”

Rotorcraft Handling Qualities Engineering: Managing the Tension between Safety and Performance 32nd Alexander A. Nikolsky Honorary Lecture

“…I have promoted this treatment of handling qualities in published works, emphasizing that flight behavior should not be left to chance but rather fully simulated prior to first flight and tracked, through qualification and into service, using virtual engineering methods (Refs. [9][10][11]. The tension between the use of coveted design practices and meeting properly informed standards for handling qualities can, and should, be a positive spur to innovation and not a burden or constraint.…”