An Investigation of the Effects of Pitch-Roll (De)Coupling on Helicopter Handling Qualities
An Investigation of the Effects of Pitch-Roll (De)Coupling on Helicopter Handling Qualities

Author: National Aeronautics and Space Administration (NASA)

Publisher: Createspace Independent Publishing Platform

Published: 2018-07-17

Total Pages: 126

ISBN-13: 9781722939816

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An extensive investigation of the effects of pitch-roll coupling on helicopter handling qualities was performed by the U.S. Army and Deutsche Forschungsanstalt fur Luft- und Raumfahrt (DLR), using a NASA ground-based and a DLR in-flight simulator. Over 90 different coupling configurations were evaluated using a high gain roll-axis tracking task. The results show that although the current ADS-33C coupling criterion discriminates against those types of coupling typical of conventionally controlled helicopters, it is not always suited for the prediction of handling qualities of helicopters with modern control systems. Based on the observation that high frequency inputs during tracking are used to alleviate coupling, a frequency domain pitch-roll coupling criterion that uses the average coupling ratio between the bandwidth and neutral stability frequency is formulated. This criterion provides a more comprehensive coverage with respect to the different types of coupling, shows excellent consistency, and has the additional benefit that compliance testing data are obtained from the bandwidth/phase delay tests, so that no additional flight testing is needed. Blanken, C. L. and Pausder, H. J. and Ockier, C. J. Ames Research Center CONTROLLABILITY; COUPLING; DECOUPLING; FLIGHT CONTROL; HELICOPTER CONTROL; HELICOPTER PERFORMANCE; HELICOPTERS; PITCH (INCLINATION); ROLL; AERODYNAMIC STABILITY; AIRCRAFT SAFETY; CONTROL STABILITY; HIGH GAIN; LATERAL CONTROL; LONGITUDINAL CONTROL; SIMULATION; TRACKING (POSITION)...

Helicopter Flight Dynamics
Helicopter Flight Dynamics

Author: Gareth D. Padfield

Publisher: John Wiley & Sons

Published: 2018-11-19

Total Pages: 858

ISBN-13: 1119401054

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The Book The behaviour of helicopters and tiltrotor aircraft is so complex that understanding the physical mechanisms at work in trim, stability and response, and thus the prediction of Flying Qualities, requires a framework of analytical and numerical modelling and simulation. Good Flying Qualities are vital for ensuring that mission performance is achievable with safety and, in the first and second editions of Helicopter Flight Dynamics, a comprehensive treatment of design criteria was presented, relating to both normal and degraded Flying Qualities. Fully embracing the consequences of Degraded Flying Qualities during the design phase will contribute positively to safety. In this third edition, two new Chapters are included. Chapter 9 takes the reader on a journey from the origins of the story of Flying Qualities, tracing key contributions to the developing maturity and to the current position. Chapter 10 provides a comprehensive treatment of the Flight Dynamics of tiltrotor aircraft; informed by research activities and the limited data on operational aircraft. Many of the unique behavioural characteristics of tiltrotors are revealed for the first time in this book. The accurate prediction and assessment of Flying Qualities draws on the modelling and simulation discipline on the one hand and testing practice on the other. Checking predictions in flight requires clearly defined mission tasks, derived from realistic performance requirements. High fidelity simulations also form the basis for the design of stability and control augmentation systems, essential for conferring Level 1 Flying Qualities. The integrated description of flight dynamic modelling, simulation and flying qualities of rotorcraft forms the subject of this book, which will be of interest to engineers practising and honing their skills in research laboratories, academia and manufacturing industries, test pilots and flight test engineers, and as a reference for graduate and postgraduate students in aerospace engineering.

A Piloted Simulator Investigation of Static Stability and Stability/control Augmentation Effects on Helicopter Handling Qualities for Instrument Approach
A Piloted Simulator Investigation of Static Stability and Stability/control Augmentation Effects on Helicopter Handling Qualities for Instrument Approach

Author:

Publisher:

Published: 1980

Total Pages: 404

ISBN-13:

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A motion-base simulator was used to compare the flying qualities of three generic single-rotor helicopters during a full-attention-to-flight control task. Terminal-area VOR instrument approaches were flown with and without turbulence. The objective of this NASA/FAA study was to investigate the influence of helicopter static stability in terms of the values of cockpit control gradients as specified in the existing airworthiness criteria, and to examine the effectiveness of several types of stability control augmentation systems in improving the instrument-flight-rules capability of helicopters with reduced static stability. Two levels of static stability in the pitch, roll, and yaw axes were examined for a hingeless-rotor configuration; the variations were stable and neutral static stability in pitch and roll, and two levels of stability in yaw. For the lower level of static stability, four types of stability and control augmentation were also examined for helicopters with three rotor types: hingeless, articulated, and teetering. Pilot rating results indicate the acceptability of neutral static stability longitudinally and laterally and the need for pitch-roll attitude augmentation to achieve a satisfactory system. (Author).