Icing Encounter Flight Simulator

Transcription

1 Icing Encounter Flight Simulator Principal Investigator: Graduate Students: Michael Selig Rob Deters Glen Dimock 6-1

2 Core Technologies SMART ICING SYSTEMS Research Organization Aerodynamics and Propulsion Flight Mechanics Control and Sensor Integration Human Factors Aircraft Icing Technology IMS Functions Characterize Icing Effects Operate and Monitor IPS Envelope Protection Adaptive Control System Integration Flight Simulation Flight Test 6-2

3 Icing Encounter Flight Simulator Objectives: Function as a systems integrator by bringing together the various flight simulator components composed of an aircraft model, flight mechanics, aerodynamics, propulsion, controls, sensors, the ice protection system, the smart icing system, and human factors Perform "virtual flight tests" to examine the effects of icing on aircraft operations under a variety of conditions Approach: Develop an Icing Encounter Flight Simulator Apply the simulator to icing scenarios and experiments 6-3

4 Simulation Flowchart and Models 6-4

5 Aerodynamics Nonlinear model No stability derivatives used with current Twin Otter All coefficients determined through lookup tables In body axis 3D interpolation Data usage follows 6-5

6 Aerodynamics Component build-up Sample nonlinear coefficient data follows 6-6

7 Pitching Moment Data Pitching Moment Coefficinet Cm (de = 0) de = -26 deg (up) de = -13 deg (up) de = 7 deg (down) de = 14 deg (down) Alpha (deg) 6-7

8 Weather V Altitude Latitude Longitude Cloud Model MVD LWC Temp Calc η dη/dt η η ice η old η ice,old Also used as an icing characterization surrogate 6-8

9 Longitudinal Icing Model η wing η tail C L C D C m α δ e Icing Model Calculate K CA C L,ice C D,ice C m,ice 6-9

10 Simple Engine Model Matches max rate of climb (1600 ft/min) Matches max speed (160 knots) 6-10

11 Pitch Attitude Hold Autopilot PAH A/P θ θ ref dθ/dt δ e V time step 6-11

12 Ice Protection System dη/dt time η Temp Auto IPS Boot Cycle (BC) Ice Boot Routine η new Auto IPS BC BC = 0, off unless overide BC = 1, 1-min cycle BC = 3, 3-min cycle BC = -1, failure 6-12

13 IPS Boot Cycle Routine tslc = time since last cycle lim = 1.667e-4 Smart Start Icing Ice Boot System Review, September 30 October 1, 2002 time is in seconds Routine no η = BC = 3 yes tslc > 60 BC = 3 Boot Cycle Temp < 40 η >= 0.01 no 3 dη/dt < lim yes and autoips tslc > 180 η = tslc < 45 yes and dη/dt < lim no and autoips no yes no 1 tslc > 60 and dη/dt >= lim and autoips yes -1 η = no dη/dt>= lim and autoips BC = 1 yes yes no autoips = true no dη/dt >= lim yes BC = 3 BC = 1 η = BC = 1 End Ice Boot Routine 6-13

14 Envelope Protection (Longitudinal) V Temp θ max α Envelope α stall Max and V min C L,clean Protection Min States Throttle min C L,ice 6-14

15 Other Parameters and Models Ground reactions (landing gear) model Control deflection limits Aircraft weight Mass moments of inertia 6-15

16 Distributed Simulation Motivation: Single computer not fast enough to run all IEFS components in real-time Objective: Distribute processorintensive modules across multiple CPUs 6-16

17 Networked IEFS Components FlightGear/UIUC Model Weather Envelope Protection Ice Protection System Server External Display Glass Cockpit Icing Characterization Manual state control 6-17

18 FlightGear Baseline Code Open-source flight simulator C/C++ coding, OpenGL graphics, Multiplatform Includes several flight dynamics model (FDM) solvers and associated aircraft flight models SIS IEFS uses the NASA Langley LaRCsim FDM (NASA TM , April 1995) 6-18

19 UIUC FGFS Modifications Integration of SIS components Reconfigurable aircraft model description (over 20 aircraft models exist) Multiple aero-data formats Linear, nonlinear table lookup, mixture Wind or body axis data Full aircraft or component based data 6-19

20 Engine torque, engine gyroscopic effects, tail downwash, apparent mass effects, and more modeled (not all with the Twin Otter) Batch mode simulation Play-back mode using FDR stream Networked with server 6-20

21 FGFS/UIUC Code Architecture FlightGear FDM JSBsim YaSIM LaRCsim UIUC-Aeromodel 6-21

22 uiuc_menu() Read input file & initialize variables t = 0 uiuc_recorder() Output data uiuc_aerodeflections() Determine control surface deflections LaRCsim Compute new aircraft state t > 0 uiuc_wrapper() Calculate aircraft forces & moments uiuc_coefficients() Sum aerodynamic coefficients t > t ice uiuc_engine() Engine forces & moments uiuc_gear() Landing gear forces & moments uiuc_ice() Compute iced coefficients 6-22

23 External Display Microsoft Flight Simulator 2002 (MSFS) used in display mode for the out-thewindow view. Driven over the network in so-called "slew mode" using aircraft state data from FGFS MSFS cannot be adapted to simulate aircraft icing 6-23

24 6-24

25 6-25

26 Glass Cockpit Has gone through several iterations Based partly on code by Brian Fuesz, Frasca International Uses OpenGL Incorporates SIS components: IPS and Envelope Protection 6-26

27 6-27

28 Example Setup 6-28

29 Scenarios Develop fictional icing encounter accident/incident (event) scenarios to demonstrate Ice Management System (IMS) capabilities and benefits Enact scenarios on UIUC PC-based flight simulator, with and without IMS active Two scenarios currently under development, based on historical event data: Tailplane stall Roll excursion 6-29

30 Scenario 1: Tailplane Stall Aircraft in approach configuration Partial or full use of flaps Steep and/or nonstandard approach Aircraft in high-weight, forward-cg configuration high tail down-force Crew unaware of icing severity 6-30

31 Scenario 1: Tailplane Stall : Initial descent : Descent through : Runway change (10000 ) : Icing begins : Level I IPS : Full flaps : Tail de-ice boot failure : Localizer intercept (8000 ) : Loss of longitudinal control Not to scale 6-31

32 Scenario 2: Roll Upset Aircraft in approach configuration Large droplet icing conditions Use of autopilot during known icing conditions Crew unaware of icing severity Ice accumulation behind de-ice boots 6-32

33 Scenario 2: Roll Upset : New ATC vectors : Departure : Engine problems begin : Loss of lateral control : Icing begins : Flaps deployed : Ice boots cycled : Engine failure : Return to field Not to scale 6-33

34 Summary An Icing Encounter Flight Simulator (IEFS) has been created, more work is still ahead Distributed simulation used to ensure real-time simulation Scenarios are being design and SIS components are being tested Demo follows 6-34

35 Work in Progress Implement force feedback for envelope protection (stick shaker and soft limits on control surface deflections) Resolve some issues that exist with the aerodynamic data (manifested in handling qualities) Obtain lateral asymmetric icing model and envelope protection model when available (roll upset scenario) Move forward with demo development 6-35

36 Recommendations for Future Work Increase the fidelity and function of the models Engine model Autopilot and envelope protection models Lateral aerodynamics, including spin entry due to icing Incorporate icing characterization models Navigation models Expand the number of aircraft models from one to three, including a general aviation aircraft and commuter jet 6-36

37 Recommendations for Future Work Exploit the current framework Simulate real accident scenarios and study them Use the simulator as an engineering tool for analysis of aircraft icing encounters 6-37