1SimLab 1993

INTRODUCTION

This is the Fiscal Year 1993 Annual Report from the NASA-Ames Simulation Laboratories(SimLab), of the Flight Systems and Simulation Research Division.

This document is intended to report to our customers and management on the SimLab events of1993. Included is a summary of the simulation investigations conducted in the facilities during thatyear, plus a summary of Simulation Technology Update Projects.

The reader is referred to a corresponding document, published by SimLab and entitled “AmesResearch Center, SimLab,” for a description and discussion of the SimLab facilities and theircapabilities for supporting aeronautical research and enhancing flight-simulation technology.

Anthony M. CookAssistant Chief (Operations)

Flight Systems and Simulation Research DivisionNASA-Ames Research CenterMoffett Field, California 94035

1 December 1993

SimLab 1993 2

SIMLAB ACTIVITIES - FY93EXECUTIVE SUMMARY

Fiscal Year 1993 was notable for several major activities:

A. Thirteen major simulation investigations on the Vertical Motion Simulator (VMS). Thisis an increase of three additional simulations over last year’s schedule, with the samestaff, due in part to facility improvements and capability upgrades noted below.

B. Major capability integrity/upgrade improvements were acquired and integrated inaccordance with the operations/funding strategy developed in FY90.

C. The negotiation for and construction of the Evans & Sutherland ESIG-3000Computer Generated Imagery (CGI) system for the VMS, funded by the SpaceShuttle Program at $6M.

D. The last phase of a major Construction of Facilities (C of F) project to refurbishthe electrical power distribution and large motor-generator set that provides D-Cpower for the vertical motor system of the VMS. Also the last of three phases of amajor facility integrity upgrade to the heating, ventilation, and air-conditioning(HVAC) systems.

E. Recompetition of the SimLab Support Service Contract. In addition a wage andhiring freeze was placed in effect on the SYRE Support Service Contract.

F. Six papers by SimLab authors were presented at the AIAA (American Institute ofAeronautics and Astronautics) Simulation Technologies Conference, Monterey,CA, in August 1993.

A. The 13 research simulation investigations conducted in the VMS system duringFY93 are shown on the following schedule. The studies ranged from rotorcraft han-dling qualities and performance issues, Automated NOE flight, and High Speed CivilTransport studies, to derotation, tire loads, drag chutes, and automatic landingstudies for the Space Shuttle Orbiter.

PROJECT CUSTOMER(s)TFTA ArmyHigh Speed Civil Transport BoeingCivil Tilt Rotor FAA/IndustryANOE ArmySpace Shuttle (two entries) JSC/Rockwell/HoneywellX-Coupling ArmyTHRUSTVECTOR (two entries) Piasecki/ArmyMFVT STOVL McDonnell Douglas, MarinesE-7 STOVL USMC, Gen. Dynamics, G.E.MOTIVE (Simulation Technology) NASA, IndustryBobsled U.S. Olympic Committee

3SimLab 1993

B. SimLab management continued to comply with the FY90-developed strategy ofbalancing operational levels with facility integrity costs. The strategy is workingeffectively in that much of the obsolete equipment and subsystems have been re-placed or are on a replacement schedule. Considerable scrutiny of staff size toaccomplish the SimLab mission at various operational levels was performed. Non-essential positions were eliminated, while still keeping the essence of critical supportintact. The SimLab support contract staff level is now 121 people (100 SYRE + 21NSI), down from 178 four years ago, and is at the minimum for the current level oflaboratory operations. In spite of this low staff level, 13 major simulations wereconducted on the VMS, a 30% increase over FY92.

The VAX 9000 real-time host computer lease-to-buy was culminated with a leasebuyout in FY93. An electronic video switch system was acquired and installed in thereal-time network to accommodate switching between video resources and the labsand cockpits. This was an important part of the forthcoming integration of the newESIG-3000 visual scene system, discussed below.

Two new IRIS graphics systems were acquired and integrated to support growingrequirements for glass cockpit electronic displays, both head-up and head-downdisplays. In addition, replacement cockpit out-the-window visual scene monitorswere acquired to increase productivity and accommodate the new ESIG-3000 visualsystem.

C. The new ESIG-3000 Computer Generated Imagery (CGI) visual system acquisitionwas pursued during 1993. This system, funded by the Shuttle Program, was addedto a Johnson Space Center (JSC) contract acquiring multiple systems for the Shuttlesimulators at JSC. Much negotiation was required to re-specify and configure theAmes VMS system to provide the broader flexibility for a general-purpose R&Dcapability than a purely Shuttle system. This was accomplished with a great deal ofhelp from JSC personnel, including their in-house contractor CAE/Link, throughwhom the systems are being acquired. This was a good example of inter-centercollaboration to minimize procurement effort, minimize costs, and maximize thebenefit to NASA. Significant long-distance problems had to be overcome to makethis happen, but the willingness of specific, involved people, wearing NASA “hats”,not center “hats”, made it possible. Ames’ SimLab owes a particular debt to Mr. TomDiegelman of NASA JSC, for his pivotal role and NASA dedication to the project,and to Mr. Claude Robertson of CAE/Link, at JSC.

The system was delivered to Ames SimLab on October 4, 1993, and will be tested,checked-out, integrated, and operational for the next Shuttle approach and landingsimulation in February 1994.

The end result is a simulator visual system that has significant flexibility for VMSaeronautical research and development, that also shares commonality with the JSCshuttle training simulators, and the VMS at Ames. This will provide commonality andstandardization of training for shuttle astronauts for the approach and landing taskfor the Orbiter.

SimLab 1993 4

D. During a scheduled three-month maintenance period in FY93, three very importantmaintenance projects were completed on the VMS system. These were:

1. Major inspection, refurbishment, and preventive maintenance of the verticalmotion drive 12,000 HP motor-generator set.

2. Modernization upgrade of the vertical drive electrical power distribution system.

3. The above C of F projects shutdown afforded the opportunity for additional main-tenance and upgrades that were waiting in the queue for a window of opportu-nity. These included:

a) Removal and resealing of the hydraulic actuators for the yaw and longitu-dinal motion axes.

b) Replacement of all of the analog wiring from the cockpit, through thecatenary system and into the control room and labs. The new wires arehigher in quality and significantly lighter in weight.

c) Replacement of the instrumentation systems used to measure and bal-ance motor current for the vertical drive motors, with higher quality instru-ments to improve capability of torque-balancing of the motors.

Work-around scheduling, plus the lease of a portable chiller system allowed for fullfixed-base simulation investigations for the twelve weeks during which the buildingHVAC system was down.

E. The recompetition for the SimLab Support Service Contract was completed in FY93.The Source Selection Statement was signed by the Center Director in July, selectingthe incumbent contractor, SYRE. Negotiations were completed in September, andthe new contract was signed on October 7, 1993.

F. Members of the SimLab staff authored seven, and presented six papers at the AIAAFlight Simulation Conference, in Monterey, CA in August. This constituted 15% ofthe papers at the conference.

FUTURE PLANS

• Integration of the new ESIG-3000 CGI visual scene system into the real-time simulationnetwork. First full-up checkout simulation is scheduled for the first three weeks of Janu-ary 1994, and first operational simulation is the Shuttle approach and landing simulationin February.

• Continued high-quality, high-fidelity R&D simulation capability to support the NASA andnational aeronautical development programs. The VMS schedule for FY94 is enclosed.

5SimLab 1993

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7SimLab 1993

SIMULATION PROJECTS

1. ACT-TFTA 5 OCT - 6 NOV (5 wks)Aircraft model: UH-60 BlackhawkPurpose: Develop a real-time simulation of theOASYS sensor. Integrate the sensor, the radaraltimeter Kalman filter, and the high resolutionDMA with the TFTA/STAR Dynapath algorithm.

2. E-7 STOVL 9 NOV - 18 DEC (6 wks)Aircraft model: STOVL2CPurpose: To verify the viability of the STOVL2Ccontrol system for a STOVL type aircraft.

3. BOBSLED 21 DEC - 31 DEC (2 wks)Vehicle model: Olympic bobsledPurpose: Evaluation of roll-only versus roll-lateral motion to provide motion cues in supportof the U.S. Olympic Committee bobsled simula-tor development.

4. SSV-1 15 FEB - 19 MAR (5 wks)Aircraft model: Space Shuttle OrbiterPurpose: Continue research into drag chutehandling qualities, measure pilot workload, andcontinue crew training.

5. ANOE-II 15 FEB - 19 MAR (5 wks)Aircraft model: generic helicopter modelPurpose: To further develop a pilot-directedguidance interface and to assess workloadreduction afforded by automated obstacle.

6. X-COUPLING 22 FEB - 19 MAR (4 wks)Aircraft model: generic helicopter modelPurpose: To extensively test various pitch androll coupling and roll-into-pitch coupling.

7. MFVT STOVL 22 MAR - 30 APR (6 wks)Aircraft model: MFVT STOVLPurpose: Validate the concept of an IntegratedFlight/Propulsion Control System.

8. CTR4 10 MAY - 2 JUL (8 wks)Aircraft model: generic tilt rotorPurpose: To develop IFR Terminal Area proce-dures at urban vertiports and develop astrawman nine-degree approach glide slope.

9. SSV-2 7 JUN - 16 JUL (6 wks)Aircraft model: Space Shuttle OrbiterPurpose: To evaluate Pilot-Assisted Landing,study a new turbulence model, and providecrew training.

10. THRUSTVECTOR 10 MAY - 27 MAY (3 wks)19 JUL - 20 AUG (5 wks)

Aircraft model: modified Apache helicopterPurpose: To evaluate the handling qualities ofthe Piasecki Vectored Thrust Combat AgilityDemonstrator helicopter concept versus thebaseline Apache helicopter.

11. MOTIVE 23 AUG - 24 SEP (5 wks)Aircraft model: Apache helicopterPurpose: To gather data to allow developmentof an improved model of a pilot’s visual/vestibu-lar interactions in performing helicopter hover-ing tasks.

12. HSCT 23 AUG - 24 SEPT (5 wks)Aircraft model: HSCTPurpose: Evaluation of descent, approach, land-ing, and go-arounds of Boeing math model.Evaluate controls, HUD’s and HDD’s.

TECHNOLOGY UPGRADE PROJECTS

1. ESIG-3000Purpose: To prepare the SimLab facility for theintegration of the new image generation sys-tem.

2. PICOTAU–IRIS REAL-TIME SOFTWAREPurpose: To provide a real-time environmenton the IRIS computer, to develop and run graph-ics applications at a consistent and determinis-tic update rate.

SimLab 1993 8

3. VAX 4000 UPGRADEPurpose: To improve the computational speedof the VAX 4000 computer.

AIAA P APERS

AIAA PAPERSPurpose: A collection of papers discussing vari-ous aspects of work performed at the FlightSystems and Simulation Division, were writtenand presented at the AIAA Simulation Tech-nologies Conference in August of 1993.

9SimLab 1993

SIMULATION PROJECTS

SimLab 1993 10

11SimLab 1993

ACT-TFTA

GOALS:The primary goal of the Active-Terrain Following, Terrain Avoidancesimulation was to integrate and evaluate several methods of modifyingthe Dynapath trajectory based on sensed mismatches between theDefense Mapping Agency (DMA) terrain map used by Dynapath andthe “real” world represented by the Computer Generated Imagery(CGI). For example, the DMA map does not include trees, so Dynapathwould occasionally lead the pilot through a tree. The individual goalswere the following:

• develop a real-time simulation of a forward-looking sensor consis-tent with the prototype Army Obstacle Avoidance System (OASYS)Sensor;

• integrate the range sensor into the current Terrain Following,Terrain Avoidance/Systems Testbed for Avionics Research (TFTA/STAR) system using the Path Manager, whose function is tomodify the vertical component of the Dynapath trajectory using thesensor data;

• integrate an option to use a radar altimeter based Kalman Filter

SimLab 1993 12

TECHNICAL SPECIFICATIONSLab: VMSHost Computer: VAX 6000Cab: R-CABImage Generation System: CT5A with TFTA Carlisle databaseHead-Up Display: IRIS 8Head-Down Display: IRIS 7 for moving map display

whose function is to modify the verticalcomponent of the Dynapath trajectory basedon the error between DMA determined ra-dar altitude and sensed radar altitude;

• integrate a high resolution DMA terrain map(which includes tree heights) into Dynapath;and

• evaluate the utility of the various options inthe integrated system as a function of alti-tude, airspeed, and pilot performance/workload.

SIMULATION RESULTS:All objectives were satisfied. A total of 184 dataruns were completed over 14 test conditions.

Numerous pilot and researcher initiated experi-mental changes were generated and evaluatedduring the testing period supporting the TFTAflight test and research objectives.

The information gathered from this simulationwill be used as a baseline improvement for flighttest of the OASYS sensor on the UH-60 STARhelicopter. The simulation provided some work-ing data for forward-pointed, narrow beam ra-dar altimeter (FNR) research.

The option to use a radar altimeter based KalmanFilter, integrated on the UH-60 STAR, resultedin a reduced minimum flight level of 125 feet.

No significant difference was found during testruns between higher resolution and baselineresolution databases.

PRINCIPAL INVESTIGATORS:Harry SwensonNASA-Ames Research Center

Rick ZelenkaNASA-Ames Research Center

SIMULATION ENGINEERS:Frederick G. Kull Jr.SYRE/SYSCON Corporation

Carla IngramSYRE/SYSCON Corporation

13SimLab 1993

GOALS:This was the third of three E-7 STOVL (Short Take-Off/VerticalLanding) simulations performed at SimLab. The objectives were to:

• validate the concept of an Integrated Flight/Propulsion ControlSystem (IFPCS);

• evaluate the IFPCS for an ejector/augmentor powered-lift aircraftand the cockpit mechanization of pilot control inceptors; and

• evaluate the performance and flying qualities of the aircraft intransitions and vertical landings, and the control power require-ments for powered lift operations.

E-7 STOVL

SimLab 1993 14

SIMULATION RESULTS:Seven pilots flew a total of 440 data runs. Pilotsperformed precision hovering at the verticaland horizontal targets on the hover board, andshipboard landings starting from hover near theship. The control inceptor configuration andmeteorological conditions were varied for thedifferent runs.

Numerous deficiencies in the E-7 STOVL simu-lator model were found in the previous simula-tion. In an attempt to correct them, researchersmade extensive changes to the math modelspecifications including modifications to the lim-iting logic, and new logic for control commanddistribution. In addition, a new version of soft-ware was provided for the component levelengine model and propulsion control system.

The limit protection/redistribution logic signifi-cantly expanded the envelope of the aircraft. Inhover mode, the aircraft was controllable whenoperating in crosswinds less than 20 knots.However, the aircraft could not operate in hoverbeyond a 20-knot crosswind. The aircraft wasable to successfully transition from cruise tohover and back to cruise.

It was learned that in order to design a success-ful IFPCS, the propulsion system specificationsmust be sufficiently detailed that all linear and

TECHNICAL SPECIFICATIONSLab: VMSHost Computer: VAX 9000Cab: F-CABImage Generation System: CT5AHead-Up Display: IRIS 7Head-Down Display: IRIS 8

nonlinear characteristics are fully addressedover the entire flight envelope. It was also foundthat use of a limited-displacement force incep-tor can be expected to result in unnecessarilyhigh pilot workload while maneuvering in hover.

These studies have contributed to the technol-ogy base for integrated flight/propulsion controldesign.

PRINCIPAL INVESTIGATOR:Walter McNeillNASA-Ames Research Center

SIMULATION ENGINEER:Robert MorrisonSYRE/SYSCON Corporation

Joe OgwellSYRE/SYSCON Corporation

Norm BengfordSYRE/SYSCON Corporation

15SimLab 1993

GOALS:The United States Olympic Committee, the United States BobsledFederation, and researchers from the University of California at Davisworked with NASA to design a better bobsled simulator for Olympicdriver training. The bobsled simulator in use currently is a fixed-baseworkstation, as shown in the photo.

The objective of this simulation was to evaluate the roll-only configu-ration of the motion simulator versus roll and lateral motion as well asfixed-base (no motion), in order to determine the most cost-effectivemethod for building the next generation bobsled simulator.

BOBSLED

SimLab 1993 16

TECHNICAL SPECIFICATIONSLab: VMSHost Computer: VAX 9000Cab: N-CABImage Generation System: IRISHead-Up Display: n/aHead-Down Display: n/a

SIMULATION RESULTS:Approximately 230 data runs were made. Themotion tests run in the Vertical Motion Simulatorhave provided an understanding of the trade-offs between several different motion configu-rations. The simulation has been crucial inhelping to minimize the technical risk associ-ated with the project and to guarantee thecompletion of a motion simulator in time for theFebruary 1994 Olympic Games.

PRINCIPAL INVESTIGATORS:Ken HuffmanUniversity of California at Davis

Mont HubbardUniversity of California at Davis

SIMULATION ENGINEER:Soren LaForceSYRE/SYSCON Corporation

17SimLab 1993

GOALS:This was the first entry for 1993 of the Space Shuttle Vehicle (SSV)simulation. The main emphasis of this shuttle simulation was the dragchute. Modifications to the drag chute were implemented to moreaccurately represent actual data. New wind profiles were added, inaddition to the ongoing research into tire wear, braking, and derotationperformance.

Additionally, a function that quantitatively evaluates pilot performancehas been coded into the computers to evaluate pilot workload. Systemdelays were included to degrade the simulation environment in thishandling qualities phase.

Crew training was conducted during the latter part of the session.

SSV-1

SimLab 1993 18

TECHNICAL SPECIFICATIONSLab: VMSHost Computer: VAX 6000Cab: S-CABImage Generation System: DIG1A with shuttle 392, 492, and 592 databaseHead-Up Display: IRIS 10Head-Down Display: IRIS 4, IRIS 7, and IRIS 8

SIMULATION RESULTS:A total of 1,774 approach and landings werecompleted. The drag chute has been slightlymodified based on information learned fromthis simulation and concurrent wind tunnel test-ing.

Preliminary results of the drag chute show thatthe measured forces can be represented bymodifying the baseline chute model with a five-degree angle offset and minor force uncertaintyvariables. Driving the HUD derotation cue withpitch rate proved to be a useful indicator, espe-cially when each HUD tick mark was set at onedegree per second. Using the auto pitch com-mand as a cue proved useless as there is atendency to try to chase the command symboland over control. The cost function still remainsto be evaluated, but preliminary indicationsshow that there is a correlation between track-ing performance and function value. The Multi-function Electronic Displays (MEDs) underwentanother alteration and most reactions werepositive. The wind profiles were more realisticthereby enhancing the overall simulation.

FUTURE PLANS:Future plans include continued VMS simulationsupport for the Space Shuttle Orbiter program.The next simulation is scheduled for the latterpart of 1993.

PRINCIPAL RESEARCHERS:Howard LawNASA-Johnson Space Center

Viet NguyenRockwell Industries, Downey

Mike ZyssRockwell Industries, Downey

SIMULATION ENGINEERS:M. Shirin SheppardSYRE/SYSCON Corporation

Frederick G. Kull Jr.SYRE/SYSCON Corporation

Edward T. FitzgeraldSYRE/SYSCON Corporation

19SimLab 1993

GOALS:Under the U.S./German Memorandum of Understanding (MOU) onhelicopter flight control, focus has been directed to the effects ofhandling qualities from pitch-due-to-roll and roll-due-to-pitch cross-coupling while flying a high bandwidth slalom course.

This fixed-base simulation was intended to repeat the initial flight testcoupling configurations from an earlier simulation, for utilization inexpanding the coupling configuration matrix and to collect data andevaluations after performing the slalom tracking task.

X-COUPLING

SimLab 1993 20

TECHNICAL SPECIFICATIONSLab: I-CABHost Computer: VAX 9000Cab: R-CABImage Generation System: CT5AHead-Up Display: n/aHead-Down Display: n/a

SIMULATION RESULTS:A total of 562 data runs were flown. Preliminaryresults show a surprisingly good agreement inhandling qualities ratings between the flight testresults and the fixed-base results for the samecontrol and rate coupling configurations. Thiswas surprising because of the lack of accelera-tion cues due to the simulation being fixed-base. Hence, for these types of coupling, thefixed-base results from the new extended con-figurations may be used to predict trends for theflight tests. On the other hand, the fixed-basesimulation results for the washed-out couplingcases did not match the flight test results for thesame configurations. It is speculated that thewashed-out coupling configurations were ahigher frequency and lower amplitude couplingthan the control and rate coupling, and hencethe handling qualities ratings would be moreinfluenced by acceleration cues or the lack ofthese cues. This is corroborated by the fact thatthe fixed-base simulation allowed higheramounts of coupling than the flight tests resultsallowed for the same ratings.

The fixed-base simulation provided a very use-ful set of data to support the U.S. Army’s shareof technical collaboration in the U.S./GermanMOU and specifically, provided the necessarydatabase to intelligently choose configurationsfor the June 1993 flight tests in Germany.

PRINCIPAL INVESTIGATOR:Chris BlankenU.S. Army Aeroflightdynamics Directorate(AVSCOM)

SIMULATION ENGINEERS:Carla IngramSYRE/SYSCON Corporation

Norm BengfordSYRE/SYSCON Corporation

21SimLab 1993

GOALS:This is the second simulation looking into Automated Nap-of-the-Earth(ANOE) helicopter flight. ANOE flight is a computer assisted mode offlight that will allow the pilot to fly low and fast during poor visibilityconditions. This project had two basic modes of operation; manualmode and Pilot Directed Guidance (PDG) mode. In the manual mode,the controls function in a standard fashion. In the PDG mode, the cycliccontrols the reference post location, the collective controls the setaltitude clearance, and the pedals are not used. The guidance uses thereference post location and the set altitude clearance along withsensor information to calculate heading and flight path angle com-mands which move the helicopter around or over obstacles.

The objectives were to:• further develop the PDG interface and associated displays based

on pilot feedback;• assess the pilot workload reduction afforded by the automated

obstacle avoidance with PDG interface; and

ANOE II

SimLab 1993 22

TECHNICAL SPECIFICATIONSLab: I-CABHost Computer: VAX 9000Cab: R-CABImage Generation System: CT5AHead-Up Display: Integrated Helmet & Display Sighting System (IHADSS) Head TrackerHead-Down Display: moving map

• when the pilot tried to force the aircraftopposite to the guidance command, thehelicopter entered an uncontrollable oscilla-tion;

• when the commanded radar altitude is setabove the tree level, the sensor/guidancesystem should not respond to trees (thesensor/guidance continues to generate com-mands when it should not); and

• occasional spikes occur in the flight pathcommand from the automatic system.

• determine what changes need to be madeto the automatic system to improve obstacleavoidance and allow smoother maneuver-ing.

SIMULATION RESULTS:A total of 65 data runs were flown by three pilots.The pilots learned to work with the automaticsystem to best plan their flights along the nomi-nal course. The data and comments indicatedthat there was a workload reduction with theautomatic system and that there was more timeto search the area for targets with the automaticsystem, especially under reduced visibility con-ditions.

Pilot feedback on the nominal post and refer-ence post symbology revealed a preference forthe inverted wickets for the nominal posts anda triangular reference post. The size of thewickets gave the pilots an indication of distanceand the shape gave an indication of the direc-tion of the course. The posts that were occultedby trees were preferred over the strictly depth-cued posts. A spacing of five seconds betweennominal posts seemed to work best for thespeeds flown.

Several areas were identified as warrantingfurther improvement:

• pilots requested a way to override the auto-matic system;

SIMULATION ENGINEERS:Monique ChetelatSYRE/SYSCON Corporation

Robert GardenerNASA-Ames Research Center

PRINCIPAL RESEARCHERS:Richard CoppenbargerNASA-Ames Research Center

Victor ChengNASA-Ames Research Center

FUTURE PLANS:Another simulation is planned for FY94 to fur-ther refine the automated obstacle avoidancesystem.

23SimLab 1993

MFVT STOVL

GOALS:The objectives of The Mixed Flow Vectored Thrust (MFVT) ShortTake-Off and Vertical Landing (STOVL) simulation were to:

• validate the concept of an Integrated Flight/Propulsion ControlSystem (IFPCS);

• evaluate the IFPCS for a mixed flow vectored thrust powered liftaircraft;

• evaluate the cockpit mechanization of pilot control inceptors,including switching between flight modes; and

• evaluate the performance and flying qualities for the aircraft intransitions and vertical landings, and determine control powerrequirements for powered lift operations.

SimLab 1993 24

TECHNICAL SPECIFICATIONSLab: I-CABHost Computer: VAX 6000Cab: F-CABImage Generation System: CT5A (Seymour-Johnson database)Head-Down Display: IRIS 8Head-Up Display: FDI HUD

SIMULATION RESULTS:Seven pilots flew a total of 680 data runs toevaluate the flying qualities of the aircraft incruise, transition, and hover modes.

Five different control modes were exploredduring transition from cruise to hover including:

• an attitude stabilized system with manualcontrol of thrust and thrust deflection;

• a system with vertical and longitudinal ve-locity command;

• a system with vertical velocity and longitudi-nal acceleration command/velocity hold; and

• variants of the latter two that replaced thevertical velocity command with direct con-trol of thrust augmented at low speed with avertical velocity damper.

During hover and vertical landing, a transla-tional rate command system for control of lon-gitudinal and lateral velocity was also provided.Evaluations of these systems were performedfor decelerating approaches to hover undervisual and instrument flight conditions and forvertical landings on a runway or aboard an LPHassault ship or DD-963 class destroyer con-ducted under visual conditions. In addition,short takeoffs and rolling vertical landings werealso assessed. Further, several design variantsin the control system were explored to assesstheir influence on flying qualities.

PRINCIPAL INVESTIGATORS:Jack FranklinNASA-Ames Research Center (FSD)

Paul McDowelMcDonnell Douglas

Stephen WattsPratt and Whitney

SIMULATION ENGINEERS:Leighton QuonSYRE/SYSCON Corporation

Luong NguyenSYRE/SYSCON Corporation

Christopher SweeneySYRE/SYSCON Corporation

Duc TranNASA-Ames Research Center

25SimLab 1993

CTR4

GOALS:The Civil Tilt Rotor (CTR) simulations have been developed to intro-duce the V-22 to the Federal Aviation Administration for civil certifica-tion. Multiple approach and landing profiles under varied weatherconditions were investigated in this, the fourth project. These simula-tions will help assess the possible occurrence of problems, limitationsof the aircraft, or constraints required in the operation of tilt-rotoraircraft for civilian use in a Terminal Control Area.

The three goals of the CTR4 simulation were to:• conduct task development and flight director development to

prepare for formal Vertical Motion Simulator (VMS) evaluations inthe Fall of 1993. The focus is Instrument Flight Rating (IFR)terminal procedures with emphasis on missed approaches anddepartures from urban vertiports;

• develop specific IFR terminal procedure for a “strawman” nine-degree approach glide slope and perform preliminary evaluationand demonstration of the procedure; and

SimLab 1993 26

TECHNICAL SPECIFICATIONSLab: I-CABHost Computer: VAX 6000Cab: R-CABImage Generation System: CT5AHead-Up Display: n/aHead-Down Display: IRIS 9

• upgrade the real-time Generic Tilt RotorSimulation (GTRS) program to be compa-rable with models employed by Bell Heli-copter, Boeing Helicopter, and the Navy atNAS Patuxent River. GTRS was upgradedto account for recent aerodynamic modeldevelopments.

SIMULATION RESULTS:The objectives were successfully addressed.During the first two weeks of the simulation thebasic flight procedure was developed and re-fined. The effort was greatly assisted throughthe use of the flight path vector display underdevelopment here. The flight path vector, aug-mented by the desired “perfect” flight path,substitutes for cues a pilot uses when operatingin visual conditions near the ground. The flightpath vector display was developed furtherthroughout the simulation entry as experienceand comments were received.

The newly developed strawman nine-degreeapproach procedure features a level flight con-version to helicopter mode, followed by glideslope capture and tracking. Arriving at a criticaldecision point 200 feet above the landing sur-face at 50 knots, the pilot commits to a landingwith a final configuration change. The semi-automated configuration control developedthrough several CTR simulations ensured this

configuration change takes place in a repeat-able, controlled fashion.

The GTRS math model was evaluated andreceived favorable comments from test pilots.

FUTURE PLANS:Another simulation is planned for the fall of1993. This entry will use the Vertical MotionSimulator to further the study of Tilt-Rotor air-craft for civilian use.

PRINCIPAL INVESTIGATOR:Bill DeckerNASA-Ames Research Center

SIMULATION ENGINEERS:Carla IngramSYRE/SYSCON Corporation

Norm BengfordSYRE/SYSCON Corporation

27SimLab 1993

SSV-2

GOALS:The main emphasis of the second FY93 shuttle simulation was thedrag chute. The profile of the drag chute force has been modified andincorporated into the SimLab computers to further simulate the realchute. This experiment looked at the effects of drag chute deploymenton handling qualities during the derotation and rollout phases. Otherissues under investigation include:

• gathering Handling Qualities Ratings (HQRs) on a crosswind studyto obtain a valid sample of a cross section of landing conditions;

• incorporating and evaluating the new Justus turbulence model aspart of the crosswind study;

• evaluating the latest lakebed rolling friction model, based on datacollected at the Edwards Air Force Base lakebed runway duringthis simulation;

• evaluating the new Pilot Assisted Landing (PAL), a proposed pilotperformance monitor, to be used after extended duration flights;

• continuation of the Multifunction Electronic Displays (MEDs) studywith several new displays under evaluation;

SimLab 1993 28

TECHNICAL SPECIFICATIONSLab: VMSHost Computer: VAX 9000Cab: S-CABImage Generation System: DIG1Head-Up Display: IRIS 10Head-Down Display: IRIS 4, IRIS 7, and IRIS 8

• evaluate a proposal to reduce the accept-able cloud ceiling for Return-To-Launch Site(RTLS) conditions; and

• crew familiarization.

SIMULATION RESULTS:The goals of the SSV-2 simulation were suc-cessfully completed. A total of 1,550 data runsand 129 PAL data runs were completed.

The relatively large amplitudes of turbulenceused in the crosswind study revealed problemswith both the baseline and Justus turbulencemodels. Further investigation is necessary todetermine the source of the turbulence prob-lem.

Engineering results from the drag chute studyindicate that the maximum main gear load sav-ings occur when the drag chute disreefs justprior to nose gear touchdown. The strongestinfluence on HQRs was found to be drag chutedeploy time. The earlier the chute is deployed,the worse the HQRs.

The improvements in the performance of thePAL system made during the simulation madeit more acceptable to the pilots. However, a fewscenarios were found which confused the guid-

ance system. Further study will be necessary tomake PAL a robust system that the pilots willtrust under any circumstances.

FUTURE PLANS:Plans are to continue the twice-yearly SpaceShuttle Orbiter landing simulations and to refinethe landing systems of the Orbiter.

SIMULATION ENGINEERS:Christopher SweeneySYRE/SYSCON Corporation

Frederick G. Kull Jr.SYRE/SYSCON Corporation

Robert BardenerNASA-Ames Research Center

PRINCIPAL INVESTIGATORS:Howard LawNASA Johnson Space Center

Viet NguyenRockwell International

Mike ZyssRockwell International

29SimLab 1993

THRUSTVECTOR

GOALS:The goal of the THRUSTVECTOR simulation was to evaluate thehandling qualities of the Piasecki Vectored Thrust Combat AgilityDemonstrator (PiAC VTCAD) helicopter concept versus the baselineApache helicopter and to verify the claims made for the design. Theflight envelope of the VTCAD was also investigated.

The proposed helicopter is a modified AH-64 Apache helicopter withan auxiliary propulsion system called the Vectored Thrust DuctedPropeller (VTDP) or “Ring-Tail”. The hypothesis was that this designcan be used to achieve higher speeds and, with an added wingstructure may provide unloading of the rotor and high “g” capability atspeed.

The claims made for the design are:• an increase of maximum level flight speed to over 200 knots;• a 50% increase in maximum longitudinal acceleration and decel-

eration in level flight;

SimLab 1993 30

TECHNICAL SPECIFICATIONSLab: I-CABHost Computer: VAX 6000Cab: N-CABImage Generation System: CT5AHead-Up Display: IRIS 9Head-Down Display: IRIS 7

• a 50% decrease in minimum turn and pull-up radius at forward speeds above 95 knots;and

• Handling Qualities Ratings at least as goodas the baseline Apache.

The Apache and the PiAC VTCAD were evalu-ated against the quantitative requirements inthe ADS-33C Handling Qualities Requirementsfor Military Rotorcraft. The qualitative handlingqualities assessment used selected flight testmaneuvers from the ADS-33C and other se-lected maneuvers.

This simulation was the second session of theTHRUSTVECTOR program. The first was athree-week fixed-base session in May. Duringthat time model checkout took place in prepara-tion for the motion simulation.

qualities of the Apache helicopter. Early resultsshow several problems with the VTCAD model:

• very complex control/inceptor scheduling;• excessive bank angle in hover/low speed;

and• static sideslip instability (negative weather-

cock stability).

SIMULATION RESULTS:A total of 400 data collection runs were com-pleted out of a total of 1,400 runs. Preliminaryresults indicate that the VTCAD model did notmeet the performance goals set by Piasecki.Both qualitative and quantitative data show thatthe overall VTCAD handling qualities were nota significant improvement over the handling

PRINCIPAL INVESTIGATOR:Chris BlankenU.S. Army Aeroflightdynamics Directorate(AVSCOM)

Hossein MansurU.S. Army Aeroflightdynamics Directorate

SIMULATION ENGINEER:Charles H. Perry Jr.SYRE/SYSCON Corporation

Joe OgwellSYRE/SYSCON Corporation

31SimLab 1993

MOTIVE

GOALS:The goal of the Motive (MOTion and Visual Evaluation) simulation wasto gather data to allow development of an improved model of a pilot’svisual/vestibular interactions in performing helicopter hovering tasks.An improved model could allow for more effective development andusage of visual databases and motion systems. Emphasis was placedon the vertical and directional degrees-of-freedom.

A stability derivative model of the Apache helicopter was used, but onlyone or two degrees-of-freedom were evaluated at a time (the verticalaxis, the directional axis, or both). Several different tasks were flown:

• reposition the aircraft between specified altitudes;• hover over a point in a disturbance environment;• bob up (ascend) and bob down (descend) in front of a striped,

vertical, visual marker (barber pole);• bob up and down in front of barber poles that are placed on the

ground in front of the aircraft (like railroad tracks);• perform a yaw capture maneuver, in which the pilot is challenged

SimLab 1993 32

TECHNICAL SPECIFICATIONSLab: VMSHost Computer: VAX 6000Cab: F-CABImage Generation System: CT5AHead-Up Display: IRIS 7Head-Down Display: n/a

to quickly yaw a specified distance and alignthe Head-Up Display (HUD) with a markeron the barber pole; and

• bob up and down in front of the barber pole,using both the vertical and yaw degrees-of-freedom coupled together.

For each of these tasks, the motion cues pro-vided by the Vertical Motion Simulator werevaried as well.

PRINCIPAL INVESTIGATORS:Jeff SchroederNASA-Ames Research Center

Walt JohnsonNASA-Ames Research Center

SIMULATION ENGINEERS:Duc TranNASA-Ames Research Center

Kenneth DuisenbergSYRE/SYSCON Corporation

SIMULATION RESULTS:Eight pilots flew a total of 2,020 data runs, inaddition to over 100 training runs, to evaluatethe motion and visual tasks. To perform theirevaluations, the test plan was followed quiteclosely, though the amount of time to be spenton each task was not known prior to its perfor-mance. A few of the planned tasks were notperformed in VMS.

A vast amount of data was collected for postexperiment analysis. Results are not yet avail-able.

33SimLab 1993

HSCT-B

GOALS:The High Speed Civil Transport-Boeing (HSCT-B) simulation is part ofa government/industry program to develop the next generation SuperSonic Transport (SST) aircraft for commercial use. This simulationfocused on evaluations of descent, approach, landing, and go-aroundsof the Boeing math model, as well as evaluations of various head-upand head-down displays, and control devices.

SimLab 1993 34

TECHNICAL SPECIFICATIONSLab: I-CABHost Computer: VAX 9000Cab: S-CABImage Generation System: DIG1Head-Up Display: IRIS 10Head-Down Display: IRIS 4, IRIS 7, and IRIS 8

SIMULATION RESULTS:Early results show the simulation model per-formed very well in providing representativeHSCT characteristics for control mode assess-ment. Modifications were identified that will beincorporated for the next HSCT-B simulation inthe Vertical Motion Simulator. The simulationhas provided NASA a capability for initiatingguidance and control system and cockpit dis-play development for HSCT as well as the basisfor carrying on this technology developmentthrough to the next phase.

FUTURE PLANS:Future plans include a one-week simulationperiod in the Vertical Motion Simulator at thebeginning of FY94, and an additional four-weekmotion session later in the year.

PRINCIPAL INVESTIGATORS:Sean EngellandNASA-Ames Research Center

Jack FranklinNASA-Ames Research Center

SIMULATION ENGINEERS:M. Shirin SheppardSYRE/SYSCON Corporation

Monique ChetelatSYRE/SYSCON Corporation

35SimLab 1993

TECHNOLOGY UPGRADE PROJECTS

SimLab 1993 36

37SimLab 1993

ESIG-3000

GOALS:The goal of this project was the acquisition and integration of a state-of-the-art image generation system with existing real-time flight simu-lation resources at SimLab. The system was acquired through anexisting JSC contract, using Space Shuttle Program Funds. Integra-tion of the ESIG-3000 image generation system will provide a currentgeneration, state-of-the-art upgrade to the already world class visualflight simulation capabilities at SimLab. The ESIG-3000 provides sixhigh resolution visual channels which are configurable to supportoptions such as line-of-sight ranging, forward looking infrared andmultiple viewports. The ESIG-3000 also features advanced texturecapabilities for improved fidelity of visual flight cues. The Ames ESIGconfiguration offers both round- and flat-earth flight regimes allowingconventional and on orbit flight profiles. Other advanced featuresinclude, collision detection, height-above-terrain, laser range finder,animation sequences, transparencies, multiple illumination sources,weather, weapons, and cultural effects to name a few.

SimLab 1993 38

RESULTS:To accomplish smooth integration of the ESIG-3000 into the SimLab environment an integra-tion team was formed. The ESIG integrationproject is working under joint SYRE/NASAmanagement. SYRE is directly responsible forthe integration. The project team incorporatesall engineering and support disciplines pro-vided at SimLab. These include, host hardwareand software, applications, procurement, graph-ics and database, video, real-time, operations,maintenance, acceptance, and facilities. Eachsub-team has full responsibility for planningand execution of integration tasks related totheir specific areas of expertise. The ESIGintegration team has provided key technicalinput to the specification of the Image Genera-tor (IG), its capabilities, interface, and opera-tional requirements as well as contract lan-guage for the statement-of-work and contractdeliverables.

The ESIG-3000 and its associated databasemodeling system have been delivered to Ames.Stand-alone acceptance testing has been com-pleted. The ESIG project team is currently in theprocess of integration and test of the IG withinthe SimLab environment.

FUTURE PLANS:Integrated acceptance testing is expected to becompleted by mid-December 1993. A fully inte-grated “operational shakedown” simulation isscheduled for January 1994, followed immedi-ately by a full production shuttle simulation inFebruary 1994. The entire integration schedulefrom receipt of the IG on October 8, 1993 to full-up production simulation in February of 1994will have taken just under four months.

PRINCIPALS:Daniel A. WilkinsSYRE/SYSCON Corporation

Steve CowartNASA-Ames Research Center

39SimLab 1993

PICOTAU–IRIS REAL-TIME SOFTWARE

GOALS:To provide a real-time environment on the IRIS computer, to developand run graphics applications at a consistent and deterministic updaterate.

IRIS graphics computers from Silicon Graphics, Inc., are used atSimLab to generate symbology for the cockpit Head-Up and Head-Down Displays (HUDs & HDDs). Prior to the development of PicoTausoftware, cockpit displays were updated at variable frequencies dueto the conflicting timing constraints imposed by the IRIS video andsimulation host input/output (I/O) rates. Hence, the PicoTau projectwas initiated to provide a consistent real-time environment similarto the environment (MicroTau) which exists on the host (VAX)computers.

SimLab 1993 40

RESULTS:The PicoTau executive software was devel-oped on the IRIS computers utilizing only thesystem services and facilities provided by IRIX(the IRIS operating system); no special pur-pose device drivers were developed. PicoTauprovides the operating system extensions re-quired to configure and control real-time graph-ics applications for either stand-alone execu-tion, or execution while communicating with ahost computer. PicoTau provides users with thecapability to control execution of a graphicsapplication in accordance with a predefinedtimeline.

Cockpit displays can now be created with con-sistent frame times synchronized to the videoframe, independent of the host I/O rate. Withconsistent frame times, the ability to detectmissed intervals on the IRIS has been imple-mented in PicoTau. Consistent frame timesallow for the computation of dynamic elements,like filters, within a graphics application. Ex-trapolation of host data to align with IRISgraphic frame boundaries is also available toaccommodate the asynchronous nature ofthe host I/O.

FUTURE PLANS:Currently under development are enhance-ments to make the PicoTau system more ro-bust. In addition, a study will soon be conductedto determine the PicoTau configuration, target-ing a Multi-CPU IRIS, necessary for obtainingoptimal real-time performance. In the future,the primary enhancement to PicoTau will be theaddition of a real-time debugging capabilitythrough a user interface similar to MicroTau’sCASPRE. Other enhancements will include toolsand utilities to facilitate development and test-ing of graphics applications.

TECHNICAL SPECIFICATIONS:Silicon Graphics, Inc.IRIS Model 4D 310 VGXT

PROJECT PRINCIPALS:G. David SherrillSYRE/SYSCON Corporation

William ClevelandNASA-Ames Research Center

41SimLab 1993

GOALS:The goal of this project was to improve the computational speed of theVAX 4000 computer. SimLab uses a VAX 4000 to support simulationand system development for the VMS simulator. The VAX 4000-300could be upgraded with the same CPU chip-set as the VAX 6000. Thisupgrade would provide SimLab with an additional host with compa-rable speed to the VAX 6000 and the VAX 9000.

VAX 4000 UPGRADE

SimLab 1993 42

RESULTS:It was determined that a CPU with the speed ofthe VAX 4000-600 would greatly increase theflexibility and capabilities at SimLab. Before asimulation can be assigned to a dedicatedoperations facility, time must be made availablefor substantial debugging of simulations. Thecomputer must be able to run a complete simu-lation. A computer with the power of a VAX4000-600 greatly improves the capabilities tohandle these requirements.

The performance improvement for the newVAX 4000-600 is substantial. It now has essen-tially the same performance as the VAX 6000.For the $47,000 invested to purchase this up-grade kit this improvement has proven to be atremendous value.

FUTURE PLANS:The VAX 4000-600 is now fully operational andis currently dedicated to the integration of theESIG-3000. The VAX 4000-600 will then bemade available as a general purpose host com-puter and integrated into the simulation sched-ule along with the VAX 6000 and VAX 9000.

PRINCIPAL:T. Martin PethtelSYRE/SYSCON Services Corporation

43SimLab 1993

AIAA PAPERS

SimLab 1993 44

45SimLab 1993

AIAA PAPERS

Several technical papers from engineers in the Flight Systems and Simulation Reserach Divisionwere written, describing various topics of interest to users of the Vertical Motion Simulation facilityat the NASA-Ames Research Center. All but one of these papers were presented at the AmericanInstitute of Aeronautics and Astronautics (AIAA) international conference held in Monterey,California, August 9 - 13. The following is a brief description of each paper:

Development and Operation of a Real-Time Simulationat the NASA-Ames Vertical Motion Simulator

Written by:Christopher Sweeney (presenter), SYRE/SYSCON CorporationShirin Sheppard, SYRE/SYSCON CorporationMonique Chetelat, SYRE/SYSCON Corporation

This paper describes the SimLab facility and the software tools necessary for an operatingsimulation. It also describes the process that a simulation undergoes from development tooperation; including acceptance of the model, validation, integration, and production phases. Thepoint is made that due to the diverse nature of the aircraft simulated and the number of simulationsconducted annually, the challenge for the simulation engineer is to develop an accurate real-timesimulation within time constraints.

Lessons Learned from a Historical Review of Piloted Aircraft Simulatorsat NASA-Ames Research Center

Written by:Seth B. Anderson (presenter), NASA-Ames Research CenterRobert H. Morrison, SYRE/SYSCON Corporation

This paper traces the conception and development of piloted aircraft simulators at NASA-AmesResearch Center, starting with the first fixed-based simulator in 1955 and continuing to the early1990’s. Problems with their development and operation and how limitations were handled arerecounted. Advances needed in simulator equipment to improve performance and fidelity to gainpilot acceptance are discussed. The uses of these simulators in various aircraft research anddevelopment programs and their importance to aircraft design and flight testing are reviewed.Lessons learned include a better understanding of the trade-off between motion cues and visualcues, the importance of simulation sophistication when examining aircraft with marginal handlingqualities characteristics, and the continuing need for upgrading simulation technology as morecomplex problems are encountered.

SimLab 1993 46

Line-of-Sight Determination in Real-Time SimulationsWritten by:Frederick G. Kull Jr., SYRE/SYSCON CorporationDonald E. Fought, Ph.D. (presenter), SYRE/SYSCON Corporation

This paper describes the selection of a method for determining line-of-sight in real-time simulationsfor the NASA-Ames Vertical Motion Simulator (VMS) facility. Five different combinations of terrainrepresentation and line-of-sight determination algorithms were tested. A gridpost terrain format,in conjunction with a Digital Differential Analyzer algorithm, was found to best meet the simulationcriteria of high speed, low storage requirements, and accuracy.

A Radar Altitude and Line-of-Sight AttachmentWritten by:Russell Sansom, SYRE/SYSCON CorporationDavid Darling (presenter), SYRE/SYSCON Corporation

This paper describes a method of overcoming much of the computational expense of finding radaraltitude and determining lines-of-sight in flight simulations over databases built from polygons.Methods are described for quantizing polygonal databases and for searching through themquickly. Various tuning parameters are explained and run-time performance figures are offered.

A High Fidelity Video Delivery System for Real-Time Flight Simulation ResearchWritten by:Daniel A. Wilkins (presenter), SYRE/SYSCON CorporationCarl C. Roach, SYRE/SYSCON Corporation

The Flight Systems and Simulation Research Laboratory (SimLab) at the NASA-Ames ResearchCenter, utilizes an extensive network of video image generation, delivery, processing, and displaysystems coupled with a large amplitude Vertical Motion Simulator (VMS) to provide a high fidelityvisual environment for flight simulation research.

This paper explores the capabilities of the current SimLab video distribution system architecturewith a view toward technical solutions implemented to resolve a variety of video interface,switching, and distribution issues common to many simulation facilities. Technical discussionsinclude a modular approach to a video switching and distribution system capable of supporting bothcoax and fiber optic video signal transmission, video scan conversion and processing techniquesfor lab observation and recording, adaptation of image generation and display system videointerfaces to industry standards, and an all-raster solution for “glass cockpit” configurationsencompassing Head-Up, Head-Down, and Out-the-Window display systems.

47SimLab 1993

Pseudo Aircraft Systems: A Multi-Aircraft Simulation Systemfor Air Traffic Control Research

Written by:Reid A. Weske (presenter), SYRE/SYSCON CorporationGeorge L. Danek, ATC Field Systems Office, NASA-Ames Research Center

Pseudo Aircraft Systems (PAS) is a computerized flight dynamics and piloting system designedto provide a high fidelity multi-aircraft real-time simulation environment to support Air Traffic Control(ATC) research. PAS is composed of three major software components that run on a network ofcomputer workstations. Functionality is distributed among these components to allow the systemto execute fast enough to support real-time operation. PAS workstations are linked by an EthernetLocal Area Network, and standard UNIX socket protocol is used for data transfer. Each componentof PAS is controlled and operated using a custom designed Graphical User Interface. Each of theseis composed of multiple windows, and many of the windows and sub-windows are used in severalof the components. Aircraft models and piloting logic are sophisticated and realistic and providecomplex maneuvering and navigational capabilities. PAS will continually be enhanced with newfeatures and improved capabilities to support ongoing and future Air Traffic Control systemdevelopment.

Enhancing Real-Time Flight Simulation Executionby Intercepting Run-Time Library Calls

Written by:Namejs Reinbachs, SYRE/SYSCON Corporation

Standard operating system input-output (I/O) procedures impose a large time penalty on real-timeprogram execution. These procedures are generally invoked by way of Run-Time Library (RTL)calls. To reduce the time penalty, as well as add flexibility, a technique has been developed todynamically intercept these calls. The design and implementation of this technique, as applied toFORTRAN WRITE statements, are described. Measured performance gains using this RTLintercept technique are on the order of 1,000%.

SimLab 1993 48

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