Status of Handling Qualities Treatment within Industrial Development Processes and Outlook for Future Needs Dipl. Ing. R. Osterhuber, Dr. Ing. M. Hanel, MEA25 Flight Control Dr. Ing. Christoph Oelker, MET4 Flight Test November 2008 Page 1
Agenda Introduction Handling Qualities (HQ) in Industrial Development Process HQ Criteria Applied in Industry Flight Testing of Handling Qualities Conclusions Questions Page 2
HQ in Industrial Development Process The Role of the FCS Today Handling Qualities are nearly completely defined by the Flight Control Laws New features like auto trim in all axes and carefree are provided Handling Quality Design via Flight Control Laws allows to normalize Handling Qualities over the whole flight envelope and configurations to optimise Ride Qualities (via feedback loops) and Handling Qualities (via Command Path) separately to optimise for different tasks which are o flight path control driven (cross acquisition, AAR, TOL, formation flying) o nose angle driven fine tracking Page 3
Industrial Development Process Design not accurate/ models not exact Cockpit Controls/SSICA Visuals (HUD, HDD) Undesired interaction HQ Requirements CLAW/ CP Design Flight Test Final AC HQ. L2 L1 T ef......... K P.... Design not accurate/ models not exact Requirements wrong Page 4
HQ Criteria applied in Industry (1) Time Response Criteria based on Experience and Experimental Derivation for Design like CAP, Frequency and Damping, Pole Criteria Gibson criteria (Dropback Criterion, Tgamma, etc.) Frequency Response Criteria based on simple Pilot Models for APC/PIO - prevention Gibson - Spider and related criteria (phase rate criterion, relative/absolute amplitude, etc.) Neal-Smith OLOP - criterion Second order (PT2) for roll ratchet analysis Pilot Opinion used in manned simulation and flight testing Cooper- Harper Rating Scale PIO- Rating Scale Page 5
HQ Criteria applied in Industry (2) 100.0 250 (0.8, 195) 200 ellipses Level 3 (0.7, 145) 150 Level 2 (0.66, 85) 100 (0.3, 60) 50 (0.5, 40) (0.375, 50) Level 1 0 0 0.5 1 1.5 Average Phase Rate Criterion relative open loop amplitude (db) Θ / stick deflection 25 20 15 10 5 0-5 -10-15 -20-25 (-180, 1.5 db) L3 L1 (-150, 1 db) (-140, 2 db) * (-100, 18 db) L2 ω nα [rad/s] 10.0 1.8974 1.3775 (-45, 1.0 6 db) Level 2-180 -160-140 -120-100 -80-60 -40 L1 (-75, 10dB) (-100, 6 db) A (-110, 0 db) open loop phase (deg) (-80, 16 db) * (-75, 4 db) (-85, 2 db) L2 (-80, -2 db) * * For applicability limits see 3.2.2.1.4. (-45, 0 db) (-55, 0 db) Level 3 Level 2 0.1 1.0 10.0 100.0 ωnα 2 n z /α 10.0 3.6 n z / α [g / rad] L2 L1 Level 1 Level 1 Level 2 & 3 10.0 3.6 1.0 0.64 0.28 0.16 ω 2 nα n z /α Relative amplitude limits 0.28 0.16 0.10 Flight Path Time Delay Definitions Page 6 0.01 0.25 0.35 1.0 ζ 1.3 2.0 SP
HQ Criteria applied in Industry (3) Qualitative Rating Handling Qualities Rating Scale (Cooper-Harper, NASA 1969) Level 1 satisfactory? Level 2 adequate? Level 3 controllable? unacceptable Page 7
HQ Criteria applied in Industry (4) Qualitative Rating PIO Rating Scale (US Test Pilot School) Description No tendency for pilot to induce undesirable motion. Undesirable motions tend to occur when pilot initiates abrupt maneuvers or attempts tight control. These motions can be prevented or eliminated by pilot technique. Undesirable motions easily induced when pilot initiates abrupt maneuvers or attempts tight control. These motions can be prevented or eliminated, but only at sacrifice to task performance or through considerable pilot attention and effort. Oscillations tend to develop when pilot initiates abrupt maneuvers or attempts tight control. Pilot must reduce gain or abandon task to recover. Divergent oscillations tend to develop when pilot initiates abrupt maneuvers or attempts tight control. Pilot must open loop by releasing or freezing the stick. Disturbance or normal control may cause divergent oscillations. Pilot must open control loop by releasing or freezing the stick. PIOR 1 2 3 4 5 6 Page 8
Flight Testing of Handling Qualities (1) operational Relevance free Manoeuvring agile Manoeuvring Closed-Loop, all Axes (Formation Flying, AAR, HQDT) Closed-Loop, one Axis (α and Nz, Rollangle or Heading Capture, HQDT) Design Relevance Open-Loop Tasks (3211, Pull-up, Push-over, 360 Roll, Roll Reversals) Wichmann et al.: High-Alpha Handling Qualities Flight Research on the NASA F/A-18 High Alpha Research Vehicle, NASA-TM-4773, 1996 Phase 3 Phase 2 Phase 1 Page 9
Flight Testing of Handling Qualities (2) Phase 1 (Control Law Familiarization) Familiarization with Control Law Characteristics Low Gain open and 1 axis Closed Loop Tasks (no HQ Ratings required) Efficient Approach of early Identification of Control Law Snags Phase 2 (PIO Resistance Testing and PIO Ratings) Application of Handling Qualities During Tracking (HQDT) Technique Attitude Capture HQDT, Formation Flying HQDT, Target Tracking HQDT, Air-to-Air Refueling (Basket Tracking HQDT) Phase 3 (Operational Handling Qualities Testing) Closed Loop Testing Clinical Attitude Captures, Formation Flying, Offset Landings, Air-to-Air Refueling, Air-to-Air Tracking Tasks with well defined Performance Criteria Cooper-Harper Ratings Page 10
Experience with the Established Industrial Development Process (1) Time Response Criteria are easy to handle and successfully provide valid guidelines for design and verification Frequency Response Criteria for APC/PIO - Prevention successfully provide guidelines for clearance and verification Problems/ Design Iterations, if requirements are not adequate/missing models are not adequate or missing Page 11
Experience with the Established Industrial Development Process Problem Examples of the Past/Future Needs (2) Page 12 Interface Problem and missing Pilot as Sensor - Modelling including Visual system: Deficient Handling due to unchanged HUD- Quickener Design after increasing the aircraft onset Criteria of Display Dynamics as function of aircraft agility (i.e. Tgamma) needed Missing/Deficient Pilot Modelling: Roll Ratchet solved by improved modelling and Command Path Redesign Further Improvement of Modelling needed Missing/Conflicting Criteria/Missing Pilot Models: Agility/Tracking Big Amplitude Criteria needed, HQ boundaries for different pilot technique (High/Low Gain Pilots) Missing Requirements: Handling during Aerobraking Dropback Problem had to be solved via On-Ground Command Path Scaling On Ground Tracking Criteria needed
Experience with the Established Industrial Development Process Flight Test (3) Phase 1 open loop testing a necessary step to support system identification/ model estimation Phase 2 PIO resistance testing essential to prove robustness of pilot-aircraft system before testing operational HQ Experience with HQDT not always satisfactory as high gain/ high amplitude inputs lead to reduction of pilot bandwidth More appropriate testing methodology for industrial environment required Phase 3 operational testing successfully performed in various tasks satisfactory results results consistent with phase 2 results FQ/ HQ testing covered sufficiently with existing methodology, except HQDT For clinical high gain/ high amplitude pilot-in-the-loop-testing better methods than HQDT are required Page 13
Summary A well defined development process w.r.t HQ exists in industry Available HQ criteria based on experience and simple pilot models successfully provide design and clearance requirements HQ testing inflight covered sufficiently with existing methodology, except HQDT In some areas (roll ratchet, display dynamics, pilot technique) better (pilot) modelling required In some areas (big amplitude maneuvring, pilot technique) accurate/new requirements would reduce design iterations Page 14
Questions? Page 15
Backup Folien Page 16
Overview of Results on Closed Loop HQ Testing (Phase 3) Formation Flying crisp precise Aircraft Response Control Sensitivity in Pitch and Roll satisfactory Air-to-Air Tracking fine Tracking Stick Freeze Exercise for low Gain Pilots high Gain Pilots need Compensation Air-to-Air Refueling very much alike flying in close Formation crisp Aircraft Response well liked Hook-up Rates (successful hook-ups vs. total attempts) greater 80% Offset Landings precise and predictable within desired Touch-down Box Page 17 Overall satisfactory HQ Evaluations
PIO Resistance Testing (1) (Handling Qualities During Tracking Technique) Normal Pilot Tracking Technique no adverse conditions adopt lowest Gain Consistent with reasonable Task Performance Special Conditions Stress, Excitement, Anxiety high Gain Technique aggressive Inputs/ Flying Purpose of PIO Resistance Testing detect HQ Deficiencies in Flight Test before In-Service Flying expose potentially hazardous Characteristics in safe Environment deliberately drive Pilots to make aggressive but controlled Inputs Key Objective of Handling Qualities During Tracking (HQDT) Amplitude most flying aggressive flying Frequency Page 18
PIO Resistance Testing (2) (Handling Qualities During Tracking Technique) Definition of HQDT Tasks Horizon Tracking (longitudinally, laterally, various Attitude Off-sets) Wind-up-Turn Tracking (50 mils Off-set) Formation Flying Tracking (attain Zero Tracking Error) Air-to-Air Refueling Basket Tracking Distinctive Requirement of HQDT Piloting Technique track Precision Aim as aggressively and as attentively as possible correct the smallest Tracking Error as rapidly as possible Expected Result Increase of Pilot Bandwidth (Pilot injected Frequency Spectrum) emulate Pilot Control Strategy when experiencing Stress, Fear, or Anxiety Page 19 30 ft line of sight
PIO Resistance Testing (3) (Handling Qualities During Tracking Technique) Build-up of HQDT Technique Step 1 track with non-aggressive, small Amplitude, low Frequency Step 2 progress to aggressive low Amplitude high Frequency Step 3 increase Amplitude at high Frequency until bang-bang Control is achieved applicable Performance Measure always minimum Tracking Error Pilot evaluation with qualitative comments and PIO ratings for each step Amplitude most flying aggressive flying Step 3 Step 1 Step 2 Frequency Page 20
Experience with PIO Resistance Testing (Phase 2) In accordance with customer requirement Handling Qualities during Tracking (HQDT) method utilised Aim is to challenge pilot-aircraft-system in flight with high gain/ high amplitude tasks Method well known from USAF Test Pilot School HQDT method divided into 3 steps (Build-up of Complexity) Step 1 and Step 2 with low and high frequency small amplitude inputs lead to expected increased pilot bandwidth Step 3 (high frequency and high amplitude) lead to Bang-Bang type inputs with reduction of pilot bandwidth (not fully understood yet) Step 3 increase of bandwidth by minor pilot compensation/ anticipation Attitude, 3g Tracking HQDT, and AAR HQDT performed without Problems Formation HQDT difficult to achieve Overall PIOR satisfactory Page 21