English Nlr Tr 83150 L Design Guidelines For
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ORIGINAL: ENGLISH NLR TR 83150 L DESIGN GUIDELINES FOR HANDLIITG QUALITIES OF FUTURE TRANSPORT AIRCRAFT WITH ACTIVE CONTROL TECHNOLOGY by W.P. de Boer, M.F.C. van Gool, C. La Burthe, O.P. Nicholas and D. Schafranek This report contains the provisional findings of an Action Group created by the GARTEUR Flight Mechanics Group of Responsables to study the handling qualities of future actively controlled transport aircraft. The responses of Industry to a questionnaire drawn up by the Action Group are presented. Based on these, present and future manual control piloting tasks are defined. Handling qualities criteria, currently used in the design of transport aircraft are presented. A flight simulator experiment is proposed to establish their applicability to ACT transport aircraft. It is anticipated that useful handling qualities guidelines for the design of those aircraft will be generated.' Prepared under the auspices of the Responsables for Flight Mechanics of the Group for Aeronautical Research and Technology in Europe (GARTEUR). Division: Flight Completed : 840401 Prepared: WCVG/& Ordernumber : 533.002 Approved : "dB/& '&P. : PTP -2- CONTENTS PREFACE LIST OF SYMBOLS AND ACRONYMS 1 INTRODUCTION 2 SUMMARY AND INTERPRETATION OF RESPONSES TO THE QUESTIONNAIRE 2.1 General 2.2 Questions and responses 3 DEFINITION OF PRESENT AND FUTURE MANLJAL CONTROL TASKS 4 EVALUATION OF AVAILABLE ANALYTICAL METHODS DESCRIBING THE PILOT-AIRCRAFT SYSTEM 4.1 General 4.2 Methods available at NLR 4.3 Methods available at RAE 4.4 Methods available at DFVLR 4.5 Methods available at ONERA 5 EXISTING CRITERIA FOR LONGITUDINAL HANDLING QUALITIES 5.1 General 5.2 Criteria using frequency domain characteristics 5.3 Criteria using time domain characteristics 5.4 Miscellaneous criteria 6 THE GENERATION OF NEW HANDLING QUALITIES GUIDELINES 6.1 Objective 6.2 Plan for a simulator investigation 6.3 Data analysis 6.4 Program size and time table 7 CONCLUSIONS AND RECOMMENDATIONS 8 REFERENCES 16 Fimres Appendix A: Terms of Reference (66 pages in total) PREFACE An Action Group was created by the GARTEUR Flight Mechanics Group of Responsables with the objective of establishing a basis for handling qualities guidelines for future transport aircraft, taking particularly into account the influence of advanced flight control systems. It is emphasized that the expression "design guidelines" used in the title has been chosen in accordance with the firm intent ofthe Group of Respons- ables not to deal with certification criteria in the present studies. The Action Group consisted of the following members: NETHERLANDS W.P. de Boer National. Aerospace Laboratory (NLR) M.F.C. van Goo1 1 FRANCE C. La Burthe Office National d7Etudes et de Recherches A6rospatiales (ONERA) UNITED KINGDOM O.P. Nicholas *) Royal Aircraft Establishment (RAE) FEDERAL REPUBLIC OF GERMANY D. Schafranek Deut sche Forschungs- und Versuchsanstalt fiir Luft- und Raumf ahrt (DFVLR) *) O.P. Nicholas replaced D.E. Fry, who was a member for the first five months. LIST OF SYMBOLS AND ACRONYMS * C Weighted sum of two aircraft variables Drb Dropback Longitudinal stick force Fe g Acceleration due to gravity G Amplitude of frequency characteristic h Altitude h Altitude command C Altitude error he Gain factor in normal acceleration equivalent Kn Z system approximation Gain factor of the pilot model in the pitch angle control loop Gain factor in pitch rate equivalent system approximat ion Mismatch of equivalent system approximation Normal load factor Limit load factor Normal load factor measured at the pilot position Normal load factor change per unit change of angle of attack Pitch rate Laplace variable Longitudinal stick displacement Time Time-to-peak pitch rate Time delay of pilot model Equivalent time delay of normal acceleration response System time delay Equivalent time delay of pitch rate response Time to double Airspeed Crossover velocity True airspeed Pilot model transfer function in the altitude (pitch angle) control loop Flight path angle Phase angle Damping ratio parameter of the equivalent system Pitch angle Pitch angle command Pitch angle error Pilot lead time constant Pilot lag time constant Numerator time constant used in the equivalent system Angular frequency Undamped natural frequency of the equivalent system Minimum bandwidth frequency Subscripts e Equivalent s s Steady state Acronyms ACT Active Control Technology AG Action Group DFVLR Deutsche Forschungs- und Versuchsanstalt fiir Luft- und Raumfahrt DLC Direct Lift Control FCS Flight Control System HOS High Order System m Head Up Display ILS Instrument Landing System IMC Instrument Meteorological Conditions LOS Low Order System MLS Microwave Landing System NLR Nationaal Lucht- en Ruimtevaartlaboratorium ONERA Office National dlEtudes et de Recherches A6rospatiale RAE Royal Aircraft Establishment RMS Root Mean Square THETA Typical Heavy Electrical Transport Aircraft VMC Visual Meteorological Conditions 1 INTRODUCTION In order to establish whether there was a need for an Action Group in the area of handling qualities guidelines for future transport aircraft the GARTEUR Flight Mechanics Group of Responsables created an Exploratory Group. The findings of this Exploratory Group have been reported in reference 1 and resulted in the establishment of an Action Group. The Terms of Reference for this Action Group have been incorporated in appendix A of the underlying report. According to the Statement of Work of these Terms of Reference the work performed in the first year was aimed at the definition of present and future manual control piloting tasks (Task-1) on the one hand and the evaluation of available analytical methods describing the pilot- aircraft system a ask-2) on the other hand. The underlying report can be considered as the formal report on Task-1 and Task-2. The information provided leads to a recommendation for the execution of a comprehensive flight simulator programme aimed at the generation of handling qualities guidelines for future transport aircraft equipped with advanced flight control systems. The outline of the report is as follows: Results of a questionnaire presented to the aircraft industries in the participating countries are given in section 2. Section 3 con- tains a description of the present and expected future manual control piloting tasks. Section 4 contains a survey of analytical methods, mainly in the form of computer programs, available in the participating institutes, in order to describe the pilot-aircraft system. Because longitudinal control has been selected as the main subject of investi- gation, existing criteria for longitudinal hanaing qualities to be used in pre and post-experimental analysis, are dealt with in section 5. In section 6 a proposal for the generation of new handling qualities guide- lines is presented, based on a simulator investigation. Section 7 con- tains the conclusions and recommendations. 2 SUMMARY AND INTERPRETATION OF THE RESPONSES TO THE QUESTIONNAIRE 2.1 General A questionnaire was drawn up by the Action Group (AG) at the beginning of 1983 and presented to Industry. In this section a summary and interpretation of the responses given will be presented. Parts of the responses that reflect the existing FAR/JAR requirements have not been mentioned. Responses have been received from the following sources: Aerospatiale (Toulouse) Airbus Industrie British Aerospace, Manchester Div. (pilot's response) British Aerospace, Manchester Div. (engineer's response) British Aerospace, Hatfield British Aerospace, Weybridge Messerschmitt - BBlkow - Blohm Fokker and Dutch certification pilots Where appropriate the Action Group interpretation of responses is presented after AG: 2.2 Questions and responses I : Do you think that the next generation transport aircraft will be basically unstable? Engineers have in mind that the definition of stability may differ according to the case: stability versus speed, angle of attack or Mach number. Some of today's aircraft are already unstable: mili- tary, most transport aircraft in the transonic regime, etc... In terms of static pitch stability, there is almost an agreement to concentrate on the neutrally stable aircraft for two reasons : a) basic instability is not necessary for economics b) difficulties with general design: position of wheels, demon- strating reliability of fuel transfer, etc... AG: The static stability of the basic aircraft will be about neu- tral in cruise conditions, it will be made stable by fuel transfer for landing. The aircraft will never be dynamically unstable. I1 : Do you think that such aircraft will have handling problems? Responses agree that by the time such aircraft are certified they will have handling qualities at least as good as those of today's aircraft in a no-failure case. Based on fighter experience, it is anticipated that special care must be taken near the edges of the flight envelope. 111: Is it allowable that handling qualities are degraded after a failure in the primary flight control system? Everybody agrees that there will be some degradation of handling qualities after failure, and that there must be a relationship between failure probability and the associated degradation in handling qualities that can be accepted. Some have the opinion that in a manual back-up mode situation handling qualities should be at least as good as today's. It is expected by some that the flight envelope will be limited when using a back-up system in order to retain a satisfactory level of handling qualities, such that specific training of pilots on back-up systems can be avoided. Also some concern is mentioned over the possibility that there will be a decrease of piloting skill due to lack of experience with manual back-up modes. AG: The handling qualities of electrical back-up systems are ex- pected to be at least as good as those of today's mechanically controlled aircraft. IV : Will future aircraft handle differently from today's aircraft? The question intended to address handling characteristics, however, some responses consider handling qualities instead. The main opinion is that the handling characteristics will be different but the handling qualities will be the same.