INTRODUCTION

This is a Fiscal Year 1992 Annual Report from the NASA-Ames SimulationLaboratories (SimLab), of the Flight Systems and Simulation Research Division.

This document is intended to report to our customers and management on theSimLab events of 1992. Included is a summary of the simulation investigationsconducted in the facilities during that year, plus a summary of three SimulationTechnology Update Projects and a description of major preventive maintenanceactivities.

The reader is referred to a corresponding document, published by SimLab andentitled “AMES RESEARCH CENTER, SIMLAB,” for a description and discussion of theSimLab facilities and their capabilities for supporting aeronautical research andenhancing flight-simulation technology.

____________Anthony M. Cook

Assistant Chief (Operations)

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

1 December 1992

SIMLAB ACTIVITIES - FY92EXECUTIVE SUMMARY

Fiscal Year 1992 was notable for several major activities:

A. Ten major simulation investigations on the VMS.

B. Major capability integrity/upgrade improvements per the operations/funding strategy developed in FY90.

C. A Space Shuttle Program Office agreement to fund a replacement $6MComputer-Generated Imagery (CGI) visual system for the VMS, urgentlyneeded per customer requirements.

D. A major facility integrity upgrade to the heating, ventilation, and air-conditioning (HVAC) systems.

E. A NASA-wide aeronautical simulation facilities assessment workshopconducted by participants from DoD, FAA, NASA, industry, and universi-ties.

A. The ten major research simulation investigations conducted on the VMS during FY92 areshown on the following schedule. The studies ranged from rotorcraft handling-qualitiesand performance issues, to Head-Up Display (HUD) format development, to derotation,tire loads, drag chutes, and automatic landing studies for the Space Shuttle orbiter.

PROJECT CUSTOMER(s)

SimVal ArmyTilt Wing FAA, Special Operations-DoDVisMoSync A/C Industry, DoDSpace Shuttle (2 Entries) JSC/Rockwell/Honeywell/SperryHiMarcs ArmySimVac Army, R/C industryTriStar II DoDComanche Army, SikorskyE7/STOVL Marines, General Dynamics, G.E.

B. SimLab management reassessed the FY90-developed strategy of balancing opera-tional levels with facility integrity costs. The strategy is effective in that much of theobsolete equipment and subsystems are on a replacement schedule. Considerablescrutiny of staff size to accomplish the SimLab mission at all operational levels wasperformed. The SimLab support contract staff level is now 125 people (103 SYRE + 22NSI), down from 178 three years ago. This level is considered the minimum for thecurrent level of laboratory operations.

In addition, three technology-upgrade projects were conducted to provide improvedsimulation fidelilty and/or improved data access:

1. Evaluation and implementation of new motion drive algorithms to improvefrequency response of the VMS. This work resulted in a paper that was presentedat the AIAA Simulation Technologies Conference in August 1992.

2. Development of an innovative scheme for an experimental cockpit lightingsystem to simulate a daylight flight environment without overpowering the visualsystem.

3. Development of a Macintosh-based system to measure and compute thefrequency response of the VMS system.

C. A plan was presented to Mr. Leonard Nicholson, Deputy Associate Administrator andDirector of the Space Shuttle program, proposing that the Space Shuttle program fundthe acquisition of a state-of-the-art CGI visual system for the VMS. The presentationalso proposed that the VMS CGI system be procured through an existing JSC CGIcontract. The acquisition of a modern visual system is crucial to maintaining the VMScapability to support leading-edge R&D programs. The current system is 15 years old,has reliability and maintainability problems, and lacks visual scene capability to meetresearch program requirements.

Based on the substantial support given to the Space Shuttle program, the importanceof the VMS for landing and takeoff studies and crew training, and potential commonalitywith the same new systems being installed in the JSC training devices, Mr. Nicholsonagreed to provide $6M of program funds for the VMS system. The new system (an ESIG-3000) should be operational on the VMS by the end of CY93.

D. During a scheduled three-month maintenance period for the building’s HVAC system,the following three very important maintenance projects were completed on the VMSmotion base:

1. Rebuilding and replacement of the Catenary System,

2. Grinding and alignment of the Lateral-Drive gear racks, and

3. Repair of leaking joints in the nitrogen Equilibrator System.

Work-around scheduling, and the lease of a portable chiller system allowed full-upmotion-simulation investigations for five of the twelve weeks during which the building’sHVAC system was down.

E. A NASA-wide workshop was conducted in July to conduct an assessment of theaeronautical simulation facilities of the agency. The principal goals of the workshopwere to help NASA:

l. Determine the extent to which the NASA simulation facilities will be ableto effectively support research program objectives over the next ten years,and

2. Identify new requirements for simulation capabilities, in order to create aframework for an investment plan for these simulation improvements.

The group was led by Mr. Frank Gomer, Manager of Human Factors, Honeywell AirTransport Systems Division, and included members from the aircraft industry, FAA,universities, DARPA, the Navy, Army, Air Force, and NASA Headquarters.

The report states: “The participants recognize that the VMS is a critical, yet under-fundednational resource, able to support investigations of any aircraft—rotorcraft, V/STOL,high-performance attack and fighter aircraft, transport aircraft, and the Space Shuttle.. . . Recent cuts in funding, coupled with the requirements to fund essential simulationimprovements, have resulted in single shift operation and a significant reduction in thenumber of simulation projects scheduled in a given year. . . . The participants identifieda compelling need to return to regular two-shift operations as soon as possible. Theparticipants strongly urge NASA to provide sufficient funding to make facility improve-ments and to operate the necessary shifts in the facilities to meet high-priority researchobjectives.”

In addition, a recent NASA Aero Blue Team Focus Group’s report listed the VMS as theonly facility in NASA considered “critical” to all five Aero Thrusts.

FUTURE PLANS

• Installation and integration of the new ESIG-3000 CGI visual scene system into theSimLab environment. Exact delivery and acceptance time frame is not yet known.However, it is expected that the system will arrive at SimLab in the last quarter of FY93.Integration and operation should be accomplished within three to six months.

• The formation of a SimLab management team to develop an operational strategy forcontinuing to provide an excellent level of high-quality support to our customers inpotentially difficult budget times. This will involve planning for new operationalguidelines, criteria for accepting and conducting simulation investigations, and review-ing capabilities versus research requirements. This activity will be initiated during thefirst months of calendar year 1993.

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SIMULATION STATISTICS

During FY92, approximately 10,500 production data runs were made by more than 120 subjectpilots in the SimLab facilities. Ten separate simulation investigations were conducted, andapproximately 1,800 simulated flight hours were provided to the researchers.

Note that simulated flight hours are equivalent to a considerably larger number of actual andcostly flight hours. In actual flight, the pilot cannot make landings without first taking off,implementing a go-around, and finally touching down. In the simulator, in order to study landingperformance, it is not necessary to take off and go around. This is especially evident in the caseof the Space Shuttle, where each landing must be preceded by a launch—a national effort atenormous cost. In contrast, the VMS afforded the astronauts the opportunity to make nearly1,800 landings in the first six-week entry, and more than 2,000 landings later in the year.

TYPES OF AIRCRAFT

The VMS and its unique vertical motion capability provides very accurate motion cues for low-altitude, slow-speed tasks: approach and landing, hover, terrain following, terrain avoidance,and nap-of-the-earth flight. Although the VMS can simulate the flight dynamics of virtually anyvehicle, the aircraft investigated this fiscal year included the Apache, Blackhawk, andComanche helicopters, several generic helicopters, an experimental tilt-wing Vertical/ShortTake-Off and Landing (V/STOL) aircraft, an E-7D Short Take-Off and Vertical Landing(STOVL) aircraft, the V/STOL Research Aircraft (VSRA) Harrier, the F-14, and the SpaceShuttle orbiter.

TYPES OF RESEARCH

Research this year included investigations of handling qualities, comparisons of Head-UpDisplays, investigations of advanced control laws, and studies intended to advance the state-of-the-art in simulation technology. In addition, the VMS was used to train the astronauts inSpace Shuttle approach and landing.

SIMLAB ACTIVITIES - FY92PROJECT SUMMARY

SIMULATION PROJECTS

1. SIMVAL II (Sep/Oct - 6 weeks)Aircraft model: Generic HelicopterPurpose: Continuing study of the phase relation-ships between the simulated model and thevisual and motion systems. Several sets of mo-tion and control gains were compared for varyinglevels of task aggressiveness.

2. TILT-WING (Oct/Nov - 5 weeks)Aircraft model: Tilt-WingPurpose: Investigate the handling qualities ofthree wing/flap movement configurations: 1) pro-grammed flap, 2) geared flap on the beep switch,and 3) geared flap on the stick.

3. VISMOSYNC (Nov/Dec - 3 weeks)Aircraft model: UH-60 BlackhawkPurpose: Investigate to determine if slalom ma-neuver tasks contributed to pilot’s tendency toexperience simulator sickness.

4. SSV 1 (Jan/Mar - 6 weeks)Aircraft model: Shuttle OrbiterPurpose: Study derotations, tire loads, dragchute, and autoland. Astronaut training.

5. HIMARCS (Apr/May - 5 weeks)Aircraft model: Generic HelicopterPurpose: Examine tradeoffs between load factorenvelope and mission performance. Explorebenefits of auxiliary thrust on mission perfor-mance and handling qualities.

6. SIMVAC (May/June - 5 weeks)Aircraft model: AH-64 Apache HelicopterPurpose: Determine the acceptable attenuationand phase lag of the force and angular velocityvector. Determine the effect of various approachlighting configurations on a pilot’s ability to main-tain an adequate deceleration profile during alanding approach.

7. TRISTAR II (June/July - 6 weeks)Aircraft model: F-14Purpose: Assess the effectiveness of variousHead-Up Display symbologies for three tasks: 1)air-to-ground, 2) unusual attitude recovery, and3) approach.

8. COMANCHE (June/July - 5 weeks)Aircraft model: Generic HelicopterPurpose: Investigate ADS-33 Degraded VisualEnvironment (DVE) tasks in a simulator.

9. SSV 2 (July/Aug - 5 weeks)Aircraft model: Shuttle OrbiterPurpose: Investigate effect of drag chute onderotation. Practice use of autoland and provideastronaut training.

10. E-7D STOVL (Aug/Sept - 6 weeks)Aircraft model: E-7D STOVL FighterPurpose: Research on integrated flight and pro-pulsion controls and Head-Up Displays.

TECHNOLOGY UPGRADE PROJECTS

1. ALGORITHM IMPROVEMENTS FOR SIMU-LATION MOTION DRIVEImplementation of revised algorithms in the mo-tion drive software to improve frequency re-sponses. A piloted evaluation was conducted. Apaper was presented at the AIAA SimulationTechnologies Conference in August 1992.

2. LIGHTING PROJECT FOR F-CABThe development of an experimental cab light-ing system to enhance the capability to simulatethe daylight flight environment without overpow-ering the computer-generated imagery system.

3. SPECTRAThe development of a significant capability tomonitor and analyze simulation system perfor-mance in real time. The application, hosted ona MacIntosh™, employs Fast-Fourier Trans-forms (FFTs) to measure the frequency re-sponse of various portions of the simulator hard-ware and software.

MAINTENANCE UPGRADE PROJECTS

1. MAJOR CORRECTIVE MAINTENANCEUpgrades and improvements were made to theCatenary System, the Lateral-Drive gear racks,and the Equilibrator System.

SIMULATION PROJECTS

SIMLAB 1992

GOALS:The SIMVAL research program is part of an ongoing study to investi-gate potential areas for improvement in the fidelity of flight simulation.Phase relationships between visual and motion systems as well asphase and gain relationships between the motion system and the mathmodel were studied extensively. In addition, several optimum sets ofmotion and control gains were sought for varying levels of taskaggressiveness.

SIMVAL 2

AC91-0555-8photo of CGI and cockpit display

1

GOALS:The SIMVAL research program is part of an ongoing study to investi-gate potential areas for improvement in the fidelity of flight simulation.Phase relationships between visual and motion systems as well asphase and gain relationships between the motion system and the mathmodel were studied extensively. In addition, several optimum sets ofmotion and control gains were sought for varying levels of taskaggressiveness.

SIMVAL 2

1

SIMLAB 1992

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 4000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System R-CAB McFadden Hydraulic Control Loader Seat Shaker

SIMULATION PROJECT ENGINEER:Robert W. GardnerNASA-Ames Research Center

PRINCIPAL INVESTIGATORS:Dan HartU.S. Army Aeroflightdynamics Directorate

William CarpenterU.S. Army Aeroflightdynamics Directorate

Phase relationships were found to be impor-tant to pilot evaluations. The pilots noticedsmall changes in the phase relationship be-tween visual and motion, but were not consis-tently able to discern whether the cause was achange in the motion or the visual.

For precise maneuvering tasks, it was foundthat minimizing the visual delay was useful,even though this action did not produce optimalphasing between visual and motion cues.

A total of 411 data runs were made.

SIMULATION RESULTS:

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 4000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System R-CAB McFadden Hydraulic Control Loader Seat Shaker

SIMULATION PROJECT ENGINEER:Robert W. GardnerNASA-Ames Research Center

PRINCIPAL INVESTIGATORS:Dan HartU.S. Army Aeroflightdynamics Directorate

William CarpenterU.S. Army Aeroflightdynamics Directorate

Phase relationships were found to be impor-tant to pilot evaluations. The pilots noticedsmall changes in the phase relationship be-tween visual and motion, but were not consis-tently able to discern whether the cause was achange in the motion or the visual.

For precise maneuvering tasks, it was foundthat minimizing the visual delay was useful,even though this action did not produce optimalphasing between visual and motion cues.

A total of 411 data runs were made.

SIMULATION RESULTS:

SIMLAB 1992

TILT ROTOR PHOTOFROM CARLA

2

TILT-WING

GOALS:The Tilt-Wing simulation focused on control law development for theGeared Flap, also called the Churchill Flap. This design utilizes thewing flap as a tab to position the wing relative to the fuselage, usingthe propeller slipstream.This project is the second Tilt-Wing investigation conducted in theVertical Motion Simulation (VMS) facility. This simulation focused onthree main points:• Correct/update the model with prior handling-quality results. Expandthe coupled-body equations of motion from 4 degrees of freedom to 7degrees of freedom.• Implement Geared Flap on the Beeper, Geared Flap Wing on theStick, and study control law implementations which exploit low-speedlongitudinal control with the intent of eliminating the tail thruster.• Study simple ground-effects model and wing-buffet model.

TILT ROTOR PHOTOFROM CARLA

2

TILT-WING

GOALS:The Tilt-Wing simulation focused on control law development for theGeared Flap, also called the Churchill Flap. This design utilizes thewing flap as a tab to position the wing relative to the fuselage, usingthe propeller slipstream.This project is the second Tilt-Wing investigation conducted in theVertical Motion Simulation (VMS) facility. This simulation focused onthree main points:• Correct/update the model with prior handling-quality results. Expandthe coupled-body equations of motion from 4 degrees of freedom to 7degrees of freedom.• Implement Geared Flap on the Beeper, Geared Flap Wing on theStick, and study control law implementations which exploit low-speedlongitudinal control with the intent of eliminating the tail thruster.• Study simple ground-effects model and wing-buffet model.

SIMLAB 1992

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System N-CAB IRIS 5 lab display for aircraft instruments IRIS 4 lab display for side view of the WAVETEK Sound Generator aircraft EAI 2000 McFadden Loader Analog Computer

SIMULATION RESULTS:

Approximately 150 data runs were made inaddition to three to four times as many practiceruns. The conventional Tilt-Wing model wasvalidated. The potential of the Churchill Flapwas demonstrated and is undergoing furthercontrol-law development. Requirements forthe horizontal tail rotor were reduced, but notyet eliminated, with the Churchill Flap.

At this writing, all of the collected data have notbeen analyzed.

FUTURE PLANS:

TheTilt-Wing model will receive further refine-ments in the areas of lateral/directional aero-dynamics, coupled-body equations of motion,and wing/flap control system.

PRINCIPAL INVESTIGATOR:Lloyd CorlissNASA-Ames Research Center

SIMULATION PROJECT ENGINEER:Steve BelsleySYRE/SYSCON Corporation

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System N-CAB IRIS 5 lab display for aircraft instruments IRIS 4 lab display for side view of the WAVETEK Sound Generator aircraft EAI 2000 McFadden Loader Analog Computer

SIMULATION RESULTS:

Approximately 150 data runs were made inaddition to three to four times as many practiceruns. The conventional Tilt-Wing model wasvalidated. The potential of the Churchill Flapwas demonstrated and is undergoing furthercontrol-law development. Requirements forthe horizontal tail rotor were reduced, but notyet eliminated, with the Churchill Flap.

At this writing, all of the collected data have notbeen analyzed.

FUTURE PLANS:

TheTilt-Wing model will receive further refine-ments in the areas of lateral/directional aero-dynamics, coupled-body equations of motion,and wing/flap control system.

PRINCIPAL INVESTIGATOR:Lloyd CorlissNASA-Ames Research Center

SIMULATION PROJECT ENGINEER:Steve BelsleySYRE/SYSCON Corporation

SIMLAB 1992

AC88-0397-1

3

VISUAL MOTION SYNCHRONIZATION(VISMOSYNC)

GOALS:The VisMoSync study is part of an ongoing study to determine thephysiological and behavioral effects of simulators on pilots: i.e., toestablish whether or not use of a motion base during a simulation helpsalleviate simulator-induced sickness.This project was the third effortconducted in the VMS Facility.

It was postulated that a large translational motion system wouldreduce the conflict between the movement sensed visually and thatperceived through the pilots' vestibular and propioceptive senses. Aspart of the study, pilots flew two tasks: a slalom task and a sawtoothtask. The pilots alternated between the two, at the prompting of theresearcher, for about one hour or until they began to show symptomsof simulator-induced sickness. Each pilot flew both tasks: one day infixed base and the other day in motion.

AC88-0397-1

3

VISUAL MOTION SYNCHRONIZATION(VISMOSYNC)

GOALS:The VisMoSync study is part of an ongoing study to determine thephysiological and behavioral effects of simulators on pilots: i.e., toestablish whether or not use of a motion base during a simulation helpsalleviate simulator-induced sickness.This project was the third effortconducted in the VMS Facility.

It was postulated that a large translational motion system wouldreduce the conflict between the movement sensed visually and thatperceived through the pilots' vestibular and propioceptive senses. Aspart of the study, pilots flew two tasks: a slalom task and a sawtoothtask. The pilots alternated between the two, at the prompting of theresearcher, for about one hour or until they began to show symptomsof simulator-induced sickness. Each pilot flew both tasks: one day infixed base and the other day in motion.

SIMLAB 1992

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host Computer PDP 11/83 SIO Computer DIG1A Digital Image Generator R-CAB IRIS 5 FDI Head-Up Display McFadden Hydraulic Control Loaders Integrated Helmet and Display Sighting System UH60 Blackhawk Helicopter Model (IHADSS) Head Tracker Conventional Helicopter Cockpit Controls

SIMULATION RESULTS:

The tasks used in this experiment were chosento be quite nauseogenic. Thirty percent of theflights in the fixed-base condition were termi-nated due to pilot discomfort, as were sixtypercent of the flights in the nominal-motioncondition. These tasks have been demon-strated to be provocative in simulators, but arenot nauseogenic when flown in the aircraft.

No systematic patterns of differences in simu-lator-induced sickness were found that areattributable to manipulation of the motion base.

The results of this experiment did not conclu-sively support the hypothesis that large trans-lational motion would reduce or amelioratesymptoms of simulator-induced sickness.

A total of 92 data runs were made.

FUTURE PLANS:

Continue to investigate the cause of simulator-induced sickness and find an engineering orprocedural solution to the problem. This willresult in simulations that better serve the train-ing and operational community.

PRINCIPAL INVESTIGATORS:Tom SharkeyMonterey Technologies

Mike McCauleyMonterey Technologies

SIMULATION PROJECT ENGINEER:Robert W. GardnerNASA-Ames Research Center

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host Computer PDP 11/83 SIO Computer DIG1A Digital Image Generator R-CAB IRIS 5 FDI Head-Up Display McFadden Hydraulic Control Loaders Integrated Helmet and Display Sighting System UH60 Blackhawk Helicopter Model (IHADSS) Head Tracker Conventional Helicopter Cockpit Controls

SIMULATION RESULTS:

The tasks used in this experiment were chosento be quite nauseogenic. Thirty percent of theflights in the fixed-base condition were termi-nated due to pilot discomfort, as were sixtypercent of the flights in the nominal-motioncondition. These tasks have been demon-strated to be provocative in simulators, but arenot nauseogenic when flown in the aircraft.

No systematic patterns of differences in simu-lator-induced sickness were found that areattributable to manipulation of the motion base.

The results of this experiment did not conclu-sively support the hypothesis that large trans-lational motion would reduce or amelioratesymptoms of simulator-induced sickness.

A total of 92 data runs were made.

FUTURE PLANS:

Continue to investigate the cause of simulator-induced sickness and find an engineering orprocedural solution to the problem. This willresult in simulations that better serve the train-ing and operational community.

PRINCIPAL INVESTIGATORS:Tom SharkeyMonterey Technologies

Mike McCauleyMonterey Technologies

SIMULATION PROJECT ENGINEER:Robert W. GardnerNASA-Ames Research Center

SIMLAB 1992

SSV 1

EC92-05165-3

4

GOALS:The Shuttle orbiter landing and rollout studies are an ongoing part of thespace program. Simulations are performed in the VMS every six monthsto fine-tune the Shuttle orbiter's landing systems. This particular studyfocused on several landing issues:• Proposed change to the Ny (lateral acceleration) feedback in the yawcontrol channel, needed during the Return To Launch Site (RTLS) phaseof flight's impact on landing and rollout.• Tire wear from the new synthetic commercial tires.• Worst-case uncertainties in preparation for the chute Detailed TestObjective (DTO).• Loads on the tires for upcoming heavy-weight vehicles at differentderotation speeds.• Proposed change in the elevon limit to offload the main gear.• Feasibility and comfort of changing the current 17- and 19-degree, 290-knot outer glide slope with an 18- and 20-degree, 300-knot outer glideslope.• Autoland runs with various sensor errors and to study takeover criteriaand techniques from those errors.• Run upcoming flight crews through a crew training matrix.

SSV 1

EC92-05165-3

4

GOALS:The Shuttle orbiter landing and rollout studies are an ongoing part of thespace program. Simulations are performed in the VMS every six monthsto fine-tune the Shuttle orbiter's landing systems. This particular studyfocused on several landing issues:• Proposed change to the Ny (lateral acceleration) feedback in the yawcontrol channel, needed during the Return To Launch Site (RTLS) phaseof flight's impact on landing and rollout.• Tire wear from the new synthetic commercial tires.• Worst-case uncertainties in preparation for the chute Detailed TestObjective (DTO).• Loads on the tires for upcoming heavy-weight vehicles at differentderotation speeds.• Proposed change in the elevon limit to offload the main gear.• Feasibility and comfort of changing the current 17- and 19-degree, 290-knot outer glide slope with an 18- and 20-degree, 300-knot outer glideslope.• Autoland runs with various sensor errors and to study takeover criteriaand techniques from those errors.• Run upcoming flight crews through a crew training matrix.

SIMLAB 1992

SIMULATION RESULTS:

Thirty-seven pilot/astronauts flew a total of1,797 data runs. Preliminary results show thatchanging the Ny feedback gain in the yawcontrol channel does not give any adverseresults to the landing and rollout phase of flight.There was very minimal tire wear with thesynthetic commercial tires. The study of thedrag chute DTO found that the DTO is ready tobe run. The proposed up-elevon limit fix ap-pears not to offload the main gear. The 18-degree and 20-degree, 300-knot outer glideslope was acceptable to the pilots. During theautoland study, the autoland DTO pilot, DaveWalker, was pleasantly surprised at the com-fortable trajectory the autoland system flewand concluded that the best take-over tech-nique would be to push the Control Stick Steer-ing (CSS) buttons rather than to hot stick intoCSS.

Two new runway visual scenes were added,Edwards's lakebed runways 15 and 23, whichwill be used for the autoland DTO. Also, thedatabases for nominal-end-of-mission runwaysof KSC 15 and Edwards's 22 and 17 wereimproved.

FUTURE PLANS:

Future plans include simulation studies, ap-proximately every six months, to continuallyupgrade and refine the landing systems of theSpace Shuttle orbiter.

PRINCIPAL INVESTIGATORS:Howard LawNASA Johnson Space Center

Viet NguyenRockwell Industries, Downey

SIMULATION PROJECT ENGINEER:Christopher SweeneySYRE/SYSCON Corporation

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 4000 Host ComputerPDP 11/83 SIO Computer DIG1 Image Generation SystemS-CAB IRIS 4 Head-Down Display (HDD), Cooper-IRIS 5 and 7 HDD Multifunction Electronic Harper and end-of-run display

Display System (MEDS) Kaiser and FDI Head-Up Displays (HUDs)Evans and Sutherland HUD symbology McFadden loader system, pedals onlyTwo Rotational Hand Controllers

SPECIAL REQUIREMENTS:Glass cockpit displays were changed for the MEDS effort for this simulation. Two IRIS 310swere used to duplicate the Acceleration Vertical Velocity Indicator, the Alpha Mach Indicator,the Attitude Direction Indicator, and Horizontal Stimulation Indicator of the left-seat instrumentpanel. The right seat had two eight-inch CRTs placed in the dashboard panel. Each CRT coulddisplay any two of the previously mentioned instruments at one time. The digital scan converteralso was used to display four pictures on one monitor.

SIMULATION RESULTS:

Thirty-seven pilot/astronauts flew a total of1,797 data runs. Preliminary results show thatchanging the Ny feedback gain in the yawcontrol channel does not give any adverseresults to the landing and rollout phase of flight.There was very minimal tire wear with thesynthetic commercial tires. The study of thedrag chute DTO found that the DTO is ready tobe run. The proposed up-elevon limit fix ap-pears not to offload the main gear. The 18-degree and 20-degree, 300-knot outer glideslope was acceptable to the pilots. During theautoland study, the autoland DTO pilot, DaveWalker, was pleasantly surprised at the com-fortable trajectory the autoland system flewand concluded that the best take-over tech-nique would be to push the Control Stick Steer-ing (CSS) buttons rather than to hot stick intoCSS.

Two new runway visual scenes were added,Edwards's lakebed runways 15 and 23, whichwill be used for the autoland DTO. Also, thedatabases for nominal-end-of-mission runwaysof KSC 15 and Edwards's 22 and 17 wereimproved.

FUTURE PLANS:

Future plans include simulation studies, ap-proximately every six months, to continuallyupgrade and refine the landing systems of theSpace Shuttle orbiter.

PRINCIPAL INVESTIGATORS:Howard LawNASA Johnson Space Center

Viet NguyenRockwell Industries, Downey

SIMULATION PROJECT ENGINEER:Christopher SweeneySYRE/SYSCON Corporation

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 4000 Host ComputerPDP 11/83 SIO Computer DIG1 Image Generation SystemS-CAB IRIS 4 Head-Down Display (HDD), Cooper-IRIS 5 and 7 HDD Multifunction Electronic Harper and end-of-run display

Display System (MEDS) Kaiser and FDI Head-Up Displays (HUDs)Evans and Sutherland HUD symbology McFadden loader system, pedals onlyTwo Rotational Hand Controllers

SPECIAL REQUIREMENTS:Glass cockpit displays were changed for the MEDS effort for this simulation. Two IRIS 310swere used to duplicate the Acceleration Vertical Velocity Indicator, the Alpha Mach Indicator,the Attitude Direction Indicator, and Horizontal Stimulation Indicator of the left-seat instrumentpanel. The right seat had two eight-inch CRTs placed in the dashboard panel. Each CRT coulddisplay any two of the previously mentioned instruments at one time. The digital scan converteralso was used to display four pictures on one monitor.

SIMLAB 1992

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

No

rmal

load

fac

tor

cap

abili

ty (

g)

1000080006000400020000X-force capability (lbf)

7.2

7.0

5.7

5.6

4.3

3.5

3.5

4.3

4.8

4.0

3.5

3.2

3.0

6.7

6.6

4.2

4.1

3.0

2.9

3.3

3.4

3.2

4.0

4.0

Satisfactory

Adequate

Unsatisfactory

Mean Cooper-Harper handling qualities ratings versus configuration

AAAAAAAAAAAA

AA

A AA

AA

AA

HIMARCS II

GOALS:The goal of this simulation experiment was to develop insight into themaneuverability requirements for aggressive helicopter maneuveringtasks such as those common to air-to-air combat. The experimentfocused on three main issues:• The trade-offs between load factor envelope and mission perfor-mance.• The mission performance and handling-qualities benefits of auxiliarythrust (x-force).• The correlation between various maneuverability and agility (MA)measures and flying qualities.Nine task scenarios were used to evaluate a given aircraft configura-tion. These tasks included two air-to-air tasks, a return-to-hover task,and six MA measures tasks. Aircraft configurations were varied bychanging the normal load factor capability and/or the maximumavailable x-force.

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

No

rmal

load

fac

tor

cap

abili

ty (

g)

1000080006000400020000X-force capability (lbf)

7.2

7.0

5.7

5.6

4.3

3.5

3.5

4.3

4.8

4.0

3.5

3.2

3.0

6.7

6.6

4.2

4.1

3.0

2.9

3.3

3.4

3.2

4.0

4.0

Satisfactory

Adequate

Unsatisfactory

Mean Cooper-Harper handling qualities ratings versus configuration

AAAAAAAAAAAA

AA

A AA

AA

AA

HIMARCS II

GOALS:The goal of this simulation experiment was to develop insight into themaneuverability requirements for aggressive helicopter maneuveringtasks such as those common to air-to-air combat. The experimentfocused on three main issues:• The trade-offs between load factor envelope and mission perfor-mance.• The mission performance and handling-qualities benefits of auxiliarythrust (x-force).• The correlation between various maneuverability and agility (MA)measures and flying qualities.Nine task scenarios were used to evaluate a given aircraft configura-tion. These tasks included two air-to-air tasks, a return-to-hover task,and six MA measures tasks. Aircraft configurations were varied bychanging the normal load factor capability and/or the maximumavailable x-force.

SIMLAB 1992

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host ComputerSIO (PDP 11/83) lab I/O IRIS 7 for Head-Down Display (HDD) symbolN-CAB ogyHDD for Terrain Map IRIS 8 for HDD MapMcFadden Loader System Mirage Tone GeneratorApache Collective Head Seat ShakerV/STOL Research Aircraft (VSRA) Cyclic

SPECIAL REQUIREMENTS:Researchers requested that two or three of the most important data-collection values for a taskbe output to the real-time terminal after each run, rather than waiting for the end-of-run printout.SimLab personnel provided a dedicated I/O line on the VAX 9000. This line could be accessedfrom any terminal, thus allowing the researcher convenient access to the data.

SIMULATION RESULTS:

The ownship required a 3.5G normal loadcapability to successfully engage a 3.5G nor-mal load capable adversary. The x-force al-lows independent speed and pitch control aswell as a smaller turn radius. This enables thepilots to maintain their track on the adversarywhile accelerating/decelerating. Pilots pre-ferred the proportional hat on the cyclic as themeans of controlling the x-force input to theaircraft. The beep-trim on the collective headshows promise as a controller. SimLab suc-cessfully completed 2,108 simulation runs inthe VMS.

FUTURE PLANS:

A simulation is planned for late 1993 to furtherexamine the issues of maneuverability andmission performance.

PRINCIPAL INVESTIGATOR:Matthew WhalleyAeroflightdynamics Directorate, U.S. ArmyAviation Systems Command

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

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host ComputerSIO (PDP 11/83) lab I/O IRIS 7 for Head-Down Display (HDD) symbolN-CAB ogyHDD for Terrain Map IRIS 8 for HDD MapMcFadden Loader System Mirage Tone GeneratorApache Collective Head Seat ShakerV/STOL Research Aircraft (VSRA) Cyclic

SPECIAL REQUIREMENTS:Researchers requested that two or three of the most important data-collection values for a taskbe output to the real-time terminal after each run, rather than waiting for the end-of-run printout.SimLab personnel provided a dedicated I/O line on the VAX 9000. This line could be accessedfrom any terminal, thus allowing the researcher convenient access to the data.

SIMULATION RESULTS:

The ownship required a 3.5G normal loadcapability to successfully engage a 3.5G nor-mal load capable adversary. The x-force al-lows independent speed and pitch control aswell as a smaller turn radius. This enables thepilots to maintain their track on the adversarywhile accelerating/decelerating. Pilots pre-ferred the proportional hat on the cyclic as themeans of controlling the x-force input to theaircraft. The beep-trim on the collective headshows promise as a controller. SimLab suc-cessfully completed 2,108 simulation runs inthe VMS.

FUTURE PLANS:

A simulation is planned for late 1993 to furtherexamine the issues of maneuverability andmission performance.

PRINCIPAL INVESTIGATOR:Matthew WhalleyAeroflightdynamics Directorate, U.S. ArmyAviation Systems Command

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

SIMLAB 1992

GOALS:The objectives of the SIMVAC simulation were:• To determine the effect of attenuation and phase lag in the motionsystem on simulation fidelity.• To determine the effect of various light configurations on a pilot’sability to maintain an adequate deceleration profile during a visuallanding approach task.

For the motion experiment, the VMS was used in either the vertical oryaw axis for two tasks: a dual-input, compensatory-tracking task, andan aggressive translation task. Between runs, the attenuation andphase lag of the motion system were systematically varied.

For the visual experiment, a landing-approach task was flown to alanding pad with one of four different lighting configurations: 1) nolights, 2) two lines of linearly spaced lights, 3) linearly spaced lightswith an additional line of exponentially spaced lights, and 4) only theexponential line of lights.

SIMVAC

AC92-0347-7

5

GOALS:The objectives of the SIMVAC simulation were:• To determine the effect of attenuation and phase lag in the motionsystem on simulation fidelity.• To determine the effect of various light configurations on a pilot’sability to maintain an adequate deceleration profile during a visuallanding approach task.

For the motion experiment, the VMS was used in either the vertical oryaw axis for two tasks: a dual-input, compensatory-tracking task, andan aggressive translation task. Between runs, the attenuation andphase lag of the motion system were systematically varied.

For the visual experiment, a landing-approach task was flown to alanding pad with one of four different lighting configurations: 1) nolights, 2) two lines of linearly spaced lights, 3) linearly spaced lightswith an additional line of exponentially spaced lights, and 4) only theexponential line of lights.

SIMVAC

AC92-0347-7

5

SIMLAB 1992

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 4000 Host Computer PDP 11/83 SIO DIG1 Image Generation System R-CAB (Crows Landing database and IRIS 7 Head-Up Display helipad with lighting systems) McFadden Control Loaders (4 axes) WAVETEK Sound Generator RUNDUM Four Strip-Chart Recorders Versatec Printer

• Performance data showed that only the pres-ence, not the quality, of the motion affected theoverall vertical tracking error. The error be-came statistically larger only during the no-motion evaluation.

• Pilot technique changed between motionconfigurations, which may indicate negativeeffects on training.

• For the aggressive translation, removal of themotion cue caused a severe degradation inperformance.

• For rotational cueing in yaw, the fidelity rat-ings were nearly invariant between fixed-baseand full motion. This seems to indicate that

low fidelity

increasing motion gain

decr

easi

ng m

otio

n ph

ase

erro

r

1

0

high

medium fidelity

←

←

SIMULATION RESULTS:

The major results follow:• The Sinacori motion fidelity hypothesis, shownin the diagram, should be modified somewhatfor vertical specific force cueing—the subjec-tive fidelity rating appears to “funnel out” fromhigh to low fidelity, rather than change in suc-cessive steps.

translational motion is more important thanrotational motion cues.

The results of the visual experiment were asfollows:

• The subject pilots preferred configuration 3:linearly spaced lights with an additional line ofexponentially spaced lights between the twolinearly spaced lines.

• They preferred any lights to no lights at all.

• An analysis of performance data is underway.A total of 793 data runs were flown by sevenpilots.

PRINCIPAL INVESTIGATORS:Jeff SchroederNASA-Ames Research Center

Dr. Walt JohnsonNASA-Ames Research Center

SIMULATION PROJECT ENGINEER:Luong NguyenSYRE/SYSCON Corporation

FUTURE PLANS:This simulation is part of an ongoing programthat looks at the effects of motion and visualcueing in simulation. Further experiments willbe performed in the future.

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 4000 Host Computer PDP 11/83 SIO DIG1 Image Generation System R-CAB (Crows Landing database and IRIS 7 Head-Up Display helipad with lighting systems) McFadden Control Loaders (4 axes) WAVETEK Sound Generator RUNDUM Four Strip-Chart Recorders Versatec Printer

• Performance data showed that only the pres-ence, not the quality, of the motion affected theoverall vertical tracking error. The error be-came statistically larger only during the no-motion evaluation.

• Pilot technique changed between motionconfigurations, which may indicate negativeeffects on training.

• For the aggressive translation, removal of themotion cue caused a severe degradation inperformance.

• For rotational cueing in yaw, the fidelity rat-ings were nearly invariant between fixed-baseand full motion. This seems to indicate that

low fidelity

increasing motion gain

decr

easi

ng m

otio

n ph

ase

erro

r

1

0

high

medium fidelity

←

←

SIMULATION RESULTS:

The major results follow:• The Sinacori motion fidelity hypothesis, shownin the diagram, should be modified somewhatfor vertical specific force cueing—the subjec-tive fidelity rating appears to “funnel out” fromhigh to low fidelity, rather than change in suc-cessive steps.

translational motion is more important thanrotational motion cues.

The results of the visual experiment were asfollows:

• The subject pilots preferred configuration 3:linearly spaced lights with an additional line ofexponentially spaced lights between the twolinearly spaced lines.

• They preferred any lights to no lights at all.

• An analysis of performance data is underway.A total of 793 data runs were flown by sevenpilots.

PRINCIPAL INVESTIGATORS:Jeff SchroederNASA-Ames Research Center

Dr. Walt JohnsonNASA-Ames Research Center

SIMULATION PROJECT ENGINEER:Luong NguyenSYRE/SYSCON Corporation

FUTURE PLANS:This simulation is part of an ongoing programthat looks at the effects of motion and visualcueing in simulation. Further experiments willbe performed in the future.

SIMLAB 1992

AC92-0385-4

6

TRISTAR II

GOALS:The overall objective of the TRISTAR simulations is to examineinformation requirements, flight symbology, and Head-Up Display(HUD) formats for military fixed-wing aircraft. Each simulation focuseson specific symbology, drive laws, and/or some combination thereof.Simulation objectives also include the development of assessmenttechniques and the building of potential information models for HUDsbased on expert data-gathering techniques.

This simulation was developed to examine improvements to fixed-wing HUD symbology, concentrating on unusual attitude recognitionand recovery and instrument approach to a landing. Also, the projectassessed test methodology and metrics used to evaluate HUD sym-bology. Finally, pilot performance and workload were investigatedduring performance of operational tasks for different attitude refer-ences, horizon cues, and approach and landing symbologies.

AC92-0385-4

6

TRISTAR II

GOALS:The overall objective of the TRISTAR simulations is to examineinformation requirements, flight symbology, and Head-Up Display(HUD) formats for military fixed-wing aircraft. Each simulation focuseson specific symbology, drive laws, and/or some combination thereof.Simulation objectives also include the development of assessmenttechniques and the building of potential information models for HUDsbased on expert data-gathering techniques.

This simulation was developed to examine improvements to fixed-wing HUD symbology, concentrating on unusual attitude recognitionand recovery and instrument approach to a landing. Also, the projectassessed test methodology and metrics used to evaluate HUD sym-bology. Finally, pilot performance and workload were investigatedduring performance of operational tasks for different attitude refer-ences, horizon cues, and approach and landing symbologies.

SIMLAB 1992

TECHNICAL SPECIFICATIONS:

Fixed-Base I-CAB VAX 6000 Host Computer PDP 11/83 SIO Computer CT5A Image Generator F-CAB IRIS 8 Head-Up Display (HUD) Image WAVETEK Sound Generator Generator 3-Axis McFadden Loader System EAI 2000 Analog Computer FDI HUD

FUTURE PLANS:

Continue the overall objectives with a focus onspecific symbology, drive laws, and configura-tions. In addition, continue to develop andrefine assessment techniques.

PRINCIPAL INVESTIGATOR:Gary KesslerNaval Air War Center, Aircraft Division

SIMULATION PROJECT ENGINEER:Carla IngramSYRE/SYSCON Corporation

SIMULATION RESULTS:

At this writing the data analysis is not yetcomplete. A total of 1,910 data runs weremade.

TECHNICAL SPECIFICATIONS:

Fixed-Base I-CAB VAX 6000 Host Computer PDP 11/83 SIO Computer CT5A Image Generator F-CAB IRIS 8 Head-Up Display (HUD) Image WAVETEK Sound Generator Generator 3-Axis McFadden Loader System EAI 2000 Analog Computer FDI HUD

FUTURE PLANS:

Continue the overall objectives with a focus onspecific symbology, drive laws, and configura-tions. In addition, continue to develop andrefine assessment techniques.

PRINCIPAL INVESTIGATOR:Gary KesslerNaval Air War Center, Aircraft Division

SIMULATION PROJECT ENGINEER:Carla IngramSYRE/SYSCON Corporation

SIMULATION RESULTS:

At this writing the data analysis is not yetcomplete. A total of 1,910 data runs weremade.

SIMLAB 1992

GOALS:In 1985 the U.S. Army’s Aviation System Command (AVSCOM)adopted a new specification for rotorcraft handling qualities, Aeronau-tical Design Standard (ADS)-33. In addition to the comprehensivequantitative requirements, ADS-33 also contains a set of flight-testdemonstration maneuvers to provide an overall assessment of theaircraft’s handling qualities. The specific maneuver definitions wereinitially formulated based on previous flight tests and Letter-of-Agree-ment requirements for the LH helicopter (renamed the RAH-66Comanche helicopter following the DEM/VAL competition). One of thegoals of the VMS Comanche simulation was to investigate and refinethe ADS-33C degraded visual environment (DVE) maneuver descrip-tions, the performance standards, and the suggested courses forcueing the pilot. Another goal was to investigate the quantitativerequirements for turn coordination. Additionally, some data wereneeded to help quantify the effects of task cueing for a joint U.S./German time-delay study.

7

DRAWING OF COMANCHE HELICOPTER

PAINTED CAMOFLAGE

COMANCHE

GOALS:In 1985 the U.S. Army’s Aviation System Command (AVSCOM)adopted a new specification for rotorcraft handling qualities, Aeronau-tical Design Standard (ADS)-33. In addition to the comprehensivequantitative requirements, ADS-33 also contains a set of flight-testdemonstration maneuvers to provide an overall assessment of theaircraft’s handling qualities. The specific maneuver definitions wereinitially formulated based on previous flight tests and Letter-of-Agree-ment requirements for the LH helicopter (renamed the RAH-66Comanche helicopter following the DEM/VAL competition). One of thegoals of the VMS Comanche simulation was to investigate and refinethe ADS-33C degraded visual environment (DVE) maneuver descrip-tions, the performance standards, and the suggested courses forcueing the pilot. Another goal was to investigate the quantitativerequirements for turn coordination. Additionally, some data wereneeded to help quantify the effects of task cueing for a joint U.S./German time-delay study.

7

DRAWING OF COMANCHE HELICOPTER

PAINTED CAMOFLAGE

COMANCHE

SIMLAB 1992

SIMULATION RESULTS:

Initially the math model dynamics were set upto include handling-qualities Level 1 and Level2 responses to assess “desired” and “adequate”performance standards, and the suggestedcourses for each DVE maneuver were as-sessed for adequate cueing to the pilot. Thiswas followed by a formal evaluation and quan-tification of the visual cueing to ensure a de-graded visual environment for task assess-ment. Handling-qualities evaluations of eachDVE maneuver with the two control-responsetypes was performed. Maneuver performancedata will be analyzed and used in the set-up ofa flight-test investigation to refine ADS-33C.For the turn-coordination investigation, vari-ous amounts of rate and control coupling (lat-eral to directional) were investigated while per-forming a slalom task. In general, nominalamounts of coupling objectionable to fixed-wing aircraft were not objectionable for the taskinvestigated. Larger amounts of coupling wereobjectionable but were thought to be unrealis-tic for rotorcraft and would probably only occurin a failed mode.The effect of altitude on the task cueing andperceived task bandwidth for the joint U.S./German time-delay study was documented ina very limited investigation. Previous ground-based results flown at 50 feet did not align within-flight results flown at 100 feet. This limitedstudy into the effects of the altitude differences

illustrated one aspect of poor visual cueing onthe ground-based simulator. That is, initialresults indicate the ground-based simulatormust be flown at 25-feet altitude to obtainresults similar to those from the in-flight tests.

FUTURE PLANS:Make use of the data gained in this experimentand incorporate the results into a flight-testprogram using the NASA Cobra helicopter withnight vision systems. This research could wellresult in revisions to the design specificationsof the Comanche helicopter.

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

Dan C. HartU.S. Army Aeroflightdynamics Directorate(AVSCOM)

SIMULATION PROJECT ENGINEER:Steve BelsleySYRE/SYSCON Corporation

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System N-CAB FDI Head-Up Display (HUD) McFadden Loaders Apache Cyclic and Collective Seat Shaker

SIMULATION RESULTS:

Initially the math model dynamics were set upto include handling-qualities Level 1 and Level2 responses to assess “desired” and “adequate”performance standards, and the suggestedcourses for each DVE maneuver were as-sessed for adequate cueing to the pilot. Thiswas followed by a formal evaluation and quan-tification of the visual cueing to ensure a de-graded visual environment for task assess-ment. Handling-qualities evaluations of eachDVE maneuver with the two control-responsetypes was performed. Maneuver performancedata will be analyzed and used in the set-up ofa flight-test investigation to refine ADS-33C.For the turn-coordination investigation, vari-ous amounts of rate and control coupling (lat-eral to directional) were investigated while per-forming a slalom task. In general, nominalamounts of coupling objectionable to fixed-wing aircraft were not objectionable for the taskinvestigated. Larger amounts of coupling wereobjectionable but were thought to be unrealis-tic for rotorcraft and would probably only occurin a failed mode.The effect of altitude on the task cueing andperceived task bandwidth for the joint U.S./German time-delay study was documented ina very limited investigation. Previous ground-based results flown at 50 feet did not align within-flight results flown at 100 feet. This limitedstudy into the effects of the altitude differences

illustrated one aspect of poor visual cueing onthe ground-based simulator. That is, initialresults indicate the ground-based simulatormust be flown at 25-feet altitude to obtainresults similar to those from the in-flight tests.

FUTURE PLANS:Make use of the data gained in this experimentand incorporate the results into a flight-testprogram using the NASA Cobra helicopter withnight vision systems. This research could wellresult in revisions to the design specificationsof the Comanche helicopter.

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

Dan C. HartU.S. Army Aeroflightdynamics Directorate(AVSCOM)

SIMULATION PROJECT ENGINEER:Steve BelsleySYRE/SYSCON Corporation

TECHNICAL SPECIFICATIONS:

Vertical Motion Simulator (VMS) VAX 9000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System N-CAB FDI Head-Up Display (HUD) McFadden Loaders Apache Cyclic and Collective Seat Shaker

SIMLAB 1992

Same photo as used inCapabilities Profile #31

EC90-0065-1shuttle landing atEdwards AFB

8

GOALS:This second Shuttle simulation for 1992 focused on the landingperformance with the new rolling friction coefficient at the Edwards AirForce Base lakebed landing site. Researchers studied several pro-posals, which included extending the nose gear and adding anautobrake system. An option to downmode to Control Stick Steering(CSS) from autoland using the trim switches on the Rotational HandController (RHC) also was studied.

The main emphasis of the simulation continued to be the autolandsystem, including the OI-24 software changes, in preparation for theSTS-47 and STS-50 mission Autoland Detailed Test Objective (DTO).Modifications to the drag chute and new wind profiles were alsostudied.

The Shuttle crews practiced orbiter landings for three weeks.

SSV 2

Same photo as used inCapabilities Profile #31

EC90-0065-1shuttle landing atEdwards AFB

8

GOALS:This second Shuttle simulation for 1992 focused on the landingperformance with the new rolling friction coefficient at the Edwards AirForce Base lakebed landing site. Researchers studied several pro-posals, which included extending the nose gear and adding anautobrake system. An option to downmode to Control Stick Steering(CSS) from autoland using the trim switches on the Rotational HandController (RHC) also was studied.

The main emphasis of the simulation continued to be the autolandsystem, including the OI-24 software changes, in preparation for theSTS-47 and STS-50 mission Autoland Detailed Test Objective (DTO).Modifications to the drag chute and new wind profiles were alsostudied.

The Shuttle crews practiced orbiter landings for three weeks.

SSV 2

SIMLAB 1992

SIMULATION RESULTS:

Thirty-one pilot/astronauts flew a total of 2,014data runs. Preliminary results show that bymodeling the frictional coefficients for thelakebed runways more exactly, heavier andmore forward center-of-gravity vehicles maybe allowed, by flight rule, to land on the lakebedrunways. The new dynamic elevon limit doesnot adversely effect the vehicle and helps tooff-load the main gear. A study of the seconddrag chute DTO (nose-in-the-air deploy of thedrag chute) shows that it is ready for use if thechute is deployed at the initiation of derotation.A study to examine the effects of extending thenose gear showed promise for reducing theload on the main gear.

An autoland study was conducted to give train-ing to the autoland DTO pilot, Dave Walker.This consisted of realistic sensor errors ap-plied to autoland runs and practice taking overfrom the autoland system. A study also wasconducted to examine a constant-decelerationautobraking system. The system was satisfac-tory to the pilots. An examination of lockedbrakes on landing revealed that this conditionwas controllable by the pilots.

FUTURE PLANS:

Future plans include simulation studies ap-proximately every six months to continuallyupgrade and refine the landing systems of theSpace Shuttle orbiter, and pilot training.

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 6000 Host ComputerPDP 11/83 SIO Computer DIG1 Image Generation SystemS-CAB Two Rotational Hand ControllersIRIS 4 Head-Down Display, Cooper-Harper IRIS 7 HDD Multifunction end-of-run display Electronic Display (MEDS)IRIS 8 HDD (MEDS) IRIS 10 Head-Up Display SymbologyKaiser and FDI HDDs McFadden Loader System, pedals only

SPECIAL REQUIREMENTS:Researchers asked for the hand controllers to be switched during the simulation; the controlleron the right seat was closer to flight hardware. An autoland box that was the mirror image of theleft-seat box was placed on the right side. The MEDS displays were also modified to comply withpilots' suggestions.

PRINCIPAL INVESTIGATORS:Howard LawNASA Johnson Space Center

Viet NguyenRockwell Industries, Downey

SIMULATION PROJECT ENGINEER:Christopher SweeneySYRE/SYSCON Corporation

SIMULATION RESULTS:

Thirty-one pilot/astronauts flew a total of 2,014data runs. Preliminary results show that bymodeling the frictional coefficients for thelakebed runways more exactly, heavier andmore forward center-of-gravity vehicles maybe allowed, by flight rule, to land on the lakebedrunways. The new dynamic elevon limit doesnot adversely effect the vehicle and helps tooff-load the main gear. A study of the seconddrag chute DTO (nose-in-the-air deploy of thedrag chute) shows that it is ready for use if thechute is deployed at the initiation of derotation.A study to examine the effects of extending thenose gear showed promise for reducing theload on the main gear.

An autoland study was conducted to give train-ing to the autoland DTO pilot, Dave Walker.This consisted of realistic sensor errors ap-plied to autoland runs and practice taking overfrom the autoland system. A study also wasconducted to examine a constant-decelerationautobraking system. The system was satisfac-tory to the pilots. An examination of lockedbrakes on landing revealed that this conditionwas controllable by the pilots.

FUTURE PLANS:

Future plans include simulation studies ap-proximately every six months to continuallyupgrade and refine the landing systems of theSpace Shuttle orbiter, and pilot training.

TECHNICAL INFORMATION:

Vertical Motion Simulator (VMS) VAX 6000 Host ComputerPDP 11/83 SIO Computer DIG1 Image Generation SystemS-CAB Two Rotational Hand ControllersIRIS 4 Head-Down Display, Cooper-Harper IRIS 7 HDD Multifunction end-of-run display Electronic Display (MEDS)IRIS 8 HDD (MEDS) IRIS 10 Head-Up Display SymbologyKaiser and FDI HDDs McFadden Loader System, pedals only

SPECIAL REQUIREMENTS:Researchers asked for the hand controllers to be switched during the simulation; the controlleron the right seat was closer to flight hardware. An autoland box that was the mirror image of theleft-seat box was placed on the right side. The MEDS displays were also modified to comply withpilots' suggestions.

PRINCIPAL INVESTIGATORS:Howard LawNASA Johnson Space Center

Viet NguyenRockwell Industries, Downey

SIMULATION PROJECT ENGINEER:Christopher SweeneySYRE/SYSCON Corporation

SIMLAB 1992

AC85-0825-2

9

E-7D STOVL

GOALS:The goals of the E-7D Short Take-Off and Vertical Landing (STOVL)simulation were to validate a design methodology for integration ofpropulsion control and flight control, investigate system performance,reduce pilot workload, and verify the adequacy of the system specifi-cations. Researchers also sought to evaluate several mechanizationsof control incepters and to expand the database for STOVL aircraftdesign.

AC85-0825-2

9

E-7D STOVL

GOALS:The goals of the E-7D Short Take-Off and Vertical Landing (STOVL)simulation were to validate a design methodology for integration ofpropulsion control and flight control, investigate system performance,reduce pilot workload, and verify the adequacy of the system specifi-cations. Researchers also sought to evaluate several mechanizationsof control incepters and to expand the database for STOVL aircraftdesign.

SIMLAB 1992

TECHNICAL SPECIFICATIONS:

Fixed-Base Simulation (I-CAB) VAX 9000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System F-CAB FHUD (Head-Up Display) IRIS computers for Head-Up and Linear Throttle Head-Down Displays RH Sidestick controller

SIMULATION RESULTS:

Flying qualities were evaluated in cruise, tran-sition, and precision hover. Eight pilots flewthe tasks, and more than 485 data runs wererecorded.

The E-7D airframe was evaluated with a de-tailed nonlinear propulsion system and a fullyintegrated flight-control-system design.

The flight-control system (FCS) performed wellwithin the limited flight envelope, especially inprecision hover tasks. Control axes weredecoupled in most cases and performed rea-sonably well. Further tuning is required toreduce the noticeable cross coupling observedin some instances. The FCS also performedwell in tracking the guidance in cruise, transi-tion, hover-to-land in a no-wind condition, andwhen the pilot flew conservatively.

However, the simulation revealed a lack ofrobustness in the flight-control-system design.The FCS could not handle large excursionssuch as turbulence with cross wind or moder-ate to large pilot control inputs, which causedfrequent loss of control power and irrecover-able divergence. Analysis of the data showedthat the FCS did not redistribute control com-mands to remaining available control effectorswhen one was saturated. This directly resulted

in unpredictable loss of control power anddivergent response.

As a result of this fixed-base flight simulation,it is clear that the performance of the FCS is notacceptable. Further improvements must bemade to correct the outstanding problems.The limiting logic which detects the controllimits must be modified such that control com-mands will be redistributed to available con-trols. Control coupling must be reduced to anacceptable level.

FUTURE PLANS:

Another simulation entry is scheduled for No-vember 1992. Additional work is being done toimprove performance of the FCS.

PRINCIPAL INVESTIGATORS:Walt McNeillNASA-Ames Research Center

Bill ChungNASA-Ames Research Center

SIMULATION PROJECT ENGINEER:Robert MorrisonSYRE/SYSCON Corporation

TECHNICAL SPECIFICATIONS:

Fixed-Base Simulation (I-CAB) VAX 9000 Host Computer PDP 11/83 SIO Computer CT5A Image Generation System F-CAB FHUD (Head-Up Display) IRIS computers for Head-Up and Linear Throttle Head-Down Displays RH Sidestick controller

SIMULATION RESULTS:

Flying qualities were evaluated in cruise, tran-sition, and precision hover. Eight pilots flewthe tasks, and more than 485 data runs wererecorded.

The E-7D airframe was evaluated with a de-tailed nonlinear propulsion system and a fullyintegrated flight-control-system design.

The flight-control system (FCS) performed wellwithin the limited flight envelope, especially inprecision hover tasks. Control axes weredecoupled in most cases and performed rea-sonably well. Further tuning is required toreduce the noticeable cross coupling observedin some instances. The FCS also performedwell in tracking the guidance in cruise, transi-tion, hover-to-land in a no-wind condition, andwhen the pilot flew conservatively.

However, the simulation revealed a lack ofrobustness in the flight-control-system design.The FCS could not handle large excursionssuch as turbulence with cross wind or moder-ate to large pilot control inputs, which causedfrequent loss of control power and irrecover-able divergence. Analysis of the data showedthat the FCS did not redistribute control com-mands to remaining available control effectorswhen one was saturated. This directly resulted

in unpredictable loss of control power anddivergent response.

As a result of this fixed-base flight simulation,it is clear that the performance of the FCS is notacceptable. Further improvements must bemade to correct the outstanding problems.The limiting logic which detects the controllimits must be modified such that control com-mands will be redistributed to available con-trols. Control coupling must be reduced to anacceptable level.

FUTURE PLANS:

Another simulation entry is scheduled for No-vember 1992. Additional work is being done toimprove performance of the FCS.

PRINCIPAL INVESTIGATORS:Walt McNeillNASA-Ames Research Center

Bill ChungNASA-Ames Research Center

SIMULATION PROJECT ENGINEER:Robert MorrisonSYRE/SYSCON Corporation

TECHNOLOGY UPDATE PROJECTS

SIMLAB 1992

AC83-0206.6

10

ALGORITHM IMPROVEMENTS FOR SIMULATION MOTION DRIVE

GOALS:The motion programs are a set of routines that are used to drive theVertical Motion Simulator (VMS). The programs calculate commandsfor VMS motion based on the accelerations calculated in the aircraftmath model.The motion programs were recently revised. Several important goalswere achieved during the revision:

• code cleanup,• capability enhancements, and• algorithmic improvements.

AC83-0206.6

10

ALGORITHM IMPROVEMENTS FOR SIMULATION MOTION DRIVE

GOALS:The motion programs are a set of routines that are used to drive theVertical Motion Simulator (VMS). The programs calculate commandsfor VMS motion based on the accelerations calculated in the aircraftmath model.The motion programs were recently revised. Several important goalswere achieved during the revision:

• code cleanup,• capability enhancements, and• algorithmic improvements.

SIMLAB 1992

PRINCIPAL INVESTIGATOR:Soren LaForceSYRE/SYSCON Corporation

RESULTS:

Code Cleanup: Obsolete code was removed.Routines were reformatted to allow easier andbetter understanding of their behavior by thesimulation engineers.

Capability Enhancements: The nature of theVMS, a research and development laboratory,is dynamic. Additional capabilities have beenadded to the existing motion programs asneeded. Several of the additions were ex-panded and made permanent additions. Forexample, the commands to the VMS may beramped up from zero to their desired valuesover a user-specified time, and both temporaryand permanent position offsets may be speci-fied.

Algorithmic Improvements: These primarily en-tailed improved digital implementation of ana-log transfer functions. The way in which theintended design of the motion programs isimplemented has been changed. The newimplementation, via the state transition method,provides accurate results from low frequenciesup to the Nyquist limit. The previous method,Euler integration, caused gain amplification atfrequencies of about 2 Hz. The gain amplifica-tion was not a problem until about 1988, whenthe Rotorcraft Simulation Motion Generator(RSMG) was installed to provide higher-band-width rotational motions. The RSMG replaceda more conventional hexapod (synergistic) ro-tational motion base. The RSMG has a signifi-cantly higher bandwidth than did the hexapod,and the gain amplification that was not percep-tible to pilots using the hexapod has provednoticeable with the RSMG.

A piloted evaluation was conducted to deter-mine if any perceptible difference would benoted. The limited evaluation suggested thatthe new implementation produced less abrupt,more realistic motion.

This work was described in an AIAA paperpresented at the Simulation Technologies con-ference at Hilton Head, S.C., in August 1992:LaForce, S., “Implementation Improvementsfor Simulation Motion Drives.”

FUTURE PLANS:

The frequency response of the current motionprograms has been measured and can beaccurately modeled. A project is underway toproduce an accurate model of the VMS andmetrics concerning its performance. Once anaccurate model is available, a compensationscheme may be devised that will further im-prove the performance of the motion system.

PRINCIPAL INVESTIGATOR:Soren LaForceSYRE/SYSCON Corporation

RESULTS:

Code Cleanup: Obsolete code was removed.Routines were reformatted to allow easier andbetter understanding of their behavior by thesimulation engineers.

Capability Enhancements: The nature of theVMS, a research and development laboratory,is dynamic. Additional capabilities have beenadded to the existing motion programs asneeded. Several of the additions were ex-panded and made permanent additions. Forexample, the commands to the VMS may beramped up from zero to their desired valuesover a user-specified time, and both temporaryand permanent position offsets may be speci-fied.

Algorithmic Improvements: These primarily en-tailed improved digital implementation of ana-log transfer functions. The way in which theintended design of the motion programs isimplemented has been changed. The newimplementation, via the state transition method,provides accurate results from low frequenciesup to the Nyquist limit. The previous method,Euler integration, caused gain amplification atfrequencies of about 2 Hz. The gain amplifica-tion was not a problem until about 1988, whenthe Rotorcraft Simulation Motion Generator(RSMG) was installed to provide higher-band-width rotational motions. The RSMG replaceda more conventional hexapod (synergistic) ro-tational motion base. The RSMG has a signifi-cantly higher bandwidth than did the hexapod,and the gain amplification that was not percep-tible to pilots using the hexapod has provednoticeable with the RSMG.

A piloted evaluation was conducted to deter-mine if any perceptible difference would benoted. The limited evaluation suggested thatthe new implementation produced less abrupt,more realistic motion.

This work was described in an AIAA paperpresented at the Simulation Technologies con-ference at Hilton Head, S.C., in August 1992:LaForce, S., “Implementation Improvementsfor Simulation Motion Drives.”

FUTURE PLANS:

The frequency response of the current motionprograms has been measured and can beaccurately modeled. A project is underway toproduce an accurate model of the VMS andmetrics concerning its performance. Once anaccurate model is available, a compensationscheme may be devised that will further im-prove the performance of the motion system.

SIMLAB 1992

11

drawing of NASA I-CABw/cutaway to show pilot

F-CAB LIGHT PROJECT

GOALS:To provide more realistic cab lighting for daylight simulations.

The F-CAB is used for the simulation of fighter aircraft, which typicallyhas the pilot enclosed under a transparent canopy. In the originallighting arrangement, the interior illumination was provided by twodimmable, incandescent lamps, positioned in front of the pilot andabove and to each side of the front window. Both the color anddirection of this illumination were obviously different from those ofdaylight coming in through a canopy. And, unless the lamps weremade very dim, reflections off the simulator optics caused excessiveinterference.

11

drawing of NASA I-CABw/cutaway to show pilot

F-CAB LIGHT PROJECT

GOALS:To provide more realistic cab lighting for daylight simulations.

The F-CAB is used for the simulation of fighter aircraft, which typicallyhas the pilot enclosed under a transparent canopy. In the originallighting arrangement, the interior illumination was provided by twodimmable, incandescent lamps, positioned in front of the pilot andabove and to each side of the front window. Both the color anddirection of this illumination were obviously different from those ofdaylight coming in through a canopy. And, unless the lamps weremade very dim, reflections off the simulator optics caused excessiveinterference.

SIMLAB 1992

TECHNICAL INFORMATION:

Fluorescent tube: Durotest Electronic dimmer: Lutron Color filter: LEE Reflector material: 3M “SOLF”

IMPLEMENTATION:

To alleviate these shortcomings, a project todevelop a special lighting system was initiated.The light source within the lamp housing is afluorescent tube, emitting light having a colortemperature of 5500°K and a Color RenditionIndex (CRI) of 91. The color temperature of thelight is then raised further by means of a -18Mired shift filter, to approximately 6000°K. Thelamp assembly, positioned above and slightlybehind the pilot’s head, contains a specialreflector to beam the light down and forward.The reflector, which extends the length of thefluorescent tube, has the cross section of anoff-axis parabola. It is made of a highly reflec-tive, clear polycarbonate sheet. This uniquematerial is being used by SimLab in a revolu-tionary manner.

Within the reflector are closely spaced lightbaffles that enable the light to go forward anddown, but not spill out sideways onto the simu-lator optics. The pilot can adjust the brightnesswith a commercially available electronic dim-mer.

RESULTS:

• The spectral characteristics of the light are afair approximation to those of the sun, or sunlitcloud.• The area illuminated includes the pilot's lap,hands on stick and throttle, etc., legs and feeton the rudder pedals, and the instrumentpanel—and nothing else.• The source of the illumination is consistentwith that coming via a canopy, e.g., shadowsare realistic.• Because light is kept off the pilot's face, it is notreflected off the optics.• Reflections in general are reduced, which inturn enables the pilot to use a higher, morerealistic brightness setting.• The overall result gives the pilot some sensa-tion of being in a fighter aircraft.

PRINCIPAL INVESTIGATOR:Richard HollowSYRE/SYSCON Corporation

TECHNICAL INFORMATION:

Fluorescent tube: Durotest Electronic dimmer: Lutron Color filter: LEE Reflector material: 3M “SOLF”

IMPLEMENTATION:

To alleviate these shortcomings, a project todevelop a special lighting system was initiated.The light source within the lamp housing is afluorescent tube, emitting light having a colortemperature of 5500°K and a Color RenditionIndex (CRI) of 91. The color temperature of thelight is then raised further by means of a -18Mired shift filter, to approximately 6000°K. Thelamp assembly, positioned above and slightlybehind the pilot’s head, contains a specialreflector to beam the light down and forward.The reflector, which extends the length of thefluorescent tube, has the cross section of anoff-axis parabola. It is made of a highly reflec-tive, clear polycarbonate sheet. This uniquematerial is being used by SimLab in a revolu-tionary manner.

Within the reflector are closely spaced lightbaffles that enable the light to go forward anddown, but not spill out sideways onto the simu-lator optics. The pilot can adjust the brightnesswith a commercially available electronic dim-mer.

RESULTS:

• The spectral characteristics of the light are afair approximation to those of the sun, or sunlitcloud.• The area illuminated includes the pilot's lap,hands on stick and throttle, etc., legs and feeton the rudder pedals, and the instrumentpanel—and nothing else.• The source of the illumination is consistentwith that coming via a canopy, e.g., shadowsare realistic.• Because light is kept off the pilot's face, it is notreflected off the optics.• Reflections in general are reduced, which inturn enables the pilot to use a higher, morerealistic brightness setting.• The overall result gives the pilot some sensa-tion of being in a fighter aircraft.

PRINCIPAL INVESTIGATOR:Richard HollowSYRE/SYSCON Corporation

SIMLAB 1992

AC92-0446

GOALS:Establish hardware and software configurations with the capacity toperform real-time system identification for the Vertical Motion Simula-tor (VMS). This system, Spectral Performance of Engineering Com-ponents from Time Response Analysis (SPECTRA), will accommo-date kilohertz bandwidths for the identification of undesirable aliasedfrequencies in the simulation environment and will be used for qualitycontrol in the implementation of various anti-aliasing methods.

SPECTRA will operate both passively, by observing controls andresponses for the identification of various simulation elements in situ,and actively, by commanding control sequences such as Gaussianand uniform noise, chirp signals, sine waves, etc. Using off-the-shelfdigital technology, SPECTRA will create frequency-domain displays,such as Bode plots and transport-delay estimations, and will performthese functions with a display-update rate of approximately once everyfive seconds. A continuous mode will be available for the investigationof nonstationary relationships.

SPECTRA

12

AC92-0446

GOALS:Establish hardware and software configurations with the capacity toperform real-time system identification for the Vertical Motion Simula-tor (VMS). This system, Spectral Performance of Engineering Com-ponents from Time Response Analysis (SPECTRA), will accommo-date kilohertz bandwidths for the identification of undesirable aliasedfrequencies in the simulation environment and will be used for qualitycontrol in the implementation of various anti-aliasing methods.

SPECTRA will operate both passively, by observing controls andresponses for the identification of various simulation elements in situ,and actively, by commanding control sequences such as Gaussianand uniform noise, chirp signals, sine waves, etc. Using off-the-shelfdigital technology, SPECTRA will create frequency-domain displays,such as Bode plots and transport-delay estimations, and will performthese functions with a display-update rate of approximately once everyfive seconds. A continuous mode will be available for the investigationof nonstationary relationships.

SPECTRA

12

SIMLAB 1992

RESULTS:

A preliminary version of SPECTRA was usedin November 1990 on the VMS during pilotevaluations of selected simulator gains. Thismaterial is published in “Ground-Based Simu-lation Evaluation of the Effects of Time Delaysand Motion on Rotorcraft Handling Qualities,”David Mitchell, Roger Hoh, Adolph Atencio,and David Key, U.S. Army AVSCOM TechnicalReport TR-91-A-010, Jan. 1992. The immedi-ate acquisition and reduction of time-seriesdata to Bode plots during these manned simu-lator flights proved to be very useful as afeedback mechanism in the investigation ofmotion-system gains as a function of flightregimes and pilot/vehicle tasks.

The VMS transport-delay characteristics, al-though exemplary, are not optimum. An initialinvestigation of motion components usingSPECTRA is in progress. Preliminary resultsindicate that the wide-bandwidth four-axesmotion controller possesses obsolescent anti-aliasing filters that contribute approximately 50msec of transport delay. In-house-developedreplacement filters have been prepared. Theyare designed around the classical notch de-sign, where the attenuation function occurs at

the host computer’s sample rate and at onemultiple thereof. Acceptance of these filters,with quality assurance from SPECTRA, willconstitute a major advance in the fidelity of theVMS system.

FUTURE PLANS:

SPECTRA’s ability to identify transport delayswill be expanded to include additional andnewly developed techniques for measuringCGI performances. Certain advances in thefield of nonlinear system identification will beincorporated into SPECTRA.

Continuity and calibration phases will be addedto the system. The possibility of automatingcertain laboratory checkout functions will beexplored. SPECTRA has promise as a suit-able platform for the development of an auto-matic quality-control system for various simu-lation components.

TECHNICAL SPECIFICATIONS:

MacIIfx™ computer with 20 MB memory, 160 MB hard drive National Instruments NB-MIO-16 interface board National Instruments NB-DMA-2800 multiple-buffering processor

SPECIAL REQUIREMENTS:

LabVIEW™icon-based scientific programming language.

PRINCIPAL INVESTIGATOR:Richard E. McFarlandNASA-Ames Research Center

RESULTS:

A preliminary version of SPECTRA was usedin November 1990 on the VMS during pilotevaluations of selected simulator gains. Thismaterial is published in “Ground-Based Simu-lation Evaluation of the Effects of Time Delaysand Motion on Rotorcraft Handling Qualities,”David Mitchell, Roger Hoh, Adolph Atencio,and David Key, U.S. Army AVSCOM TechnicalReport TR-91-A-010, Jan. 1992. The immedi-ate acquisition and reduction of time-seriesdata to Bode plots during these manned simu-lator flights proved to be very useful as afeedback mechanism in the investigation ofmotion-system gains as a function of flightregimes and pilot/vehicle tasks.

The VMS transport-delay characteristics, al-though exemplary, are not optimum. An initialinvestigation of motion components usingSPECTRA is in progress. Preliminary resultsindicate that the wide-bandwidth four-axesmotion controller possesses obsolescent anti-aliasing filters that contribute approximately 50msec of transport delay. In-house-developedreplacement filters have been prepared. Theyare designed around the classical notch de-sign, where the attenuation function occurs at

the host computer’s sample rate and at onemultiple thereof. Acceptance of these filters,with quality assurance from SPECTRA, willconstitute a major advance in the fidelity of theVMS system.

FUTURE PLANS:

SPECTRA’s ability to identify transport delayswill be expanded to include additional andnewly developed techniques for measuringCGI performances. Certain advances in thefield of nonlinear system identification will beincorporated into SPECTRA.

Continuity and calibration phases will be addedto the system. The possibility of automatingcertain laboratory checkout functions will beexplored. SPECTRA has promise as a suit-able platform for the development of an auto-matic quality-control system for various simu-lation components.

TECHNICAL SPECIFICATIONS:

MacIIfx™ computer with 20 MB memory, 160 MB hard drive National Instruments NB-MIO-16 interface board National Instruments NB-DMA-2800 multiple-buffering processor

SPECIAL REQUIREMENTS:

LabVIEW™icon-based scientific programming language.

PRINCIPAL INVESTIGATOR:Richard E. McFarlandNASA-Ames Research Center

MAINTENANCE UPGRADE PROJECTS

SIMLAB 1992

MAJOR CORRECTIVE MAINTENANCE

GOALS:During a scheduled maintenance period for the building's Heating,Ventilation, and Air Conditioning (HVAC) system, three very importantmaintenance projects were completed on the Vertical Motion Simula-tor (VMS) motion base. These were,

• a rebuild and replacement of the Catenary System,• grinding and alignment of the Lateral-Drive gear racks, and• repair of leaking joints in the nitrogen Equilibrator System.

13AC-92 0644-63 photos-in-one

MAJOR CORRECTIVE MAINTENANCE

GOALS:During a scheduled maintenance period for the building's Heating,Ventilation, and Air Conditioning (HVAC) system, three very importantmaintenance projects were completed on the Vertical Motion Simula-tor (VMS) motion base. These were,

• a rebuild and replacement of the Catenary System,• grinding and alignment of the Lateral-Drive gear racks, and• repair of leaking joints in the nitrogen Equilibrator System.

SIMLAB 1992

EQUILIBRATOR COLUMN REPAIR

The Equilibrator System is another originalVMS system that uses pressurized nitrogen toprovide a balancing force to neutralize theweight of the motion base in the vertical direc-tion. Constant leaking of the column joints,although posing no safety risk, required a lot ofongoing maintenance. A planned maintenanceproject designed a method for sealing thejoints by a welding process. The TungstenInert Gas (TIG) welding process was testedand proven by a series of full-scale prototypetests and was implemented during the sched-uled downtime. The repair was difficult toaccomplish, requiring confined space entryprocedures to access the repair areas, but washighly successful and has greatly reduced themaintenance required by the equilibrator sys-tem.

All three of these projects were accomplishedby the support services contractor responsiblefor the mechanical maintenance of the VMS.Engineering support was provided by theirown staff and the Code FSS Mechanical Engi-neering group. FY92 Maintenance Augmenta-tion money was used to help fund these projects.

CATENARY SYSTEM REPLACEMENT

The Catenary System is a pair of linked, flex-ible structures (articulated trays) connectingthe VMS motion platform to the fixed towerstructure. This is the means for the electricalpower, hydraulic hoses, signal lines, and com-munication lines to be brought on board themotion base. The catenary structure was anoriginal part of the VMS and has providedexcellent performance. After fifteen years ofcontinuous use, the catenary was nearing theend of its useful life.

A planned project provided a design upgradefor the structure, fabricated a completely newstructure, and installed it on the VMS during ascheduled shutdown. The design upgradeimproved the strength in some known areas ofweakness and changed the flexible-joint de-sign to improve maintainability. Otherwise, theoriginal design configuration and geometry wereretained to capitalize on its proven success.

LATERAL-DRIVE GEAR RACKS

Grinding and alignment of the Lateral-Drivegear rack system involved removing the ap-proximately 40 linear feet of gear rack, sendingit out for precision grinding, and reinstalling itwith improvement in the gear mesh and align-ment. Again, this was a rework of an original,highly successful VMS design. The work cor-rected some dimensional deficiencies in thegear racks to allow improvement of the gearmesh and will extend the useful life of the gearsystem for several more years.

EQUILIBRATOR COLUMN REPAIR

The Equilibrator System is another originalVMS system that uses pressurized nitrogen toprovide a balancing force to neutralize theweight of the motion base in the vertical direc-tion. Constant leaking of the column joints,although posing no safety risk, required a lot ofongoing maintenance. A planned maintenanceproject designed a method for sealing thejoints by a welding process. The TungstenInert Gas (TIG) welding process was testedand proven by a series of full-scale prototypetests and was implemented during the sched-uled downtime. The repair was difficult toaccomplish, requiring confined space entryprocedures to access the repair areas, but washighly successful and has greatly reduced themaintenance required by the equilibrator sys-tem.

All three of these projects were accomplishedby the support services contractor responsiblefor the mechanical maintenance of the VMS.Engineering support was provided by theirown staff and the Code FSS Mechanical Engi-neering group. FY92 Maintenance Augmenta-tion money was used to help fund these projects.

CATENARY SYSTEM REPLACEMENT

The Catenary System is a pair of linked, flex-ible structures (articulated trays) connectingthe VMS motion platform to the fixed towerstructure. This is the means for the electricalpower, hydraulic hoses, signal lines, and com-munication lines to be brought on board themotion base. The catenary structure was anoriginal part of the VMS and has providedexcellent performance. After fifteen years ofcontinuous use, the catenary was nearing theend of its useful life.

A planned project provided a design upgradefor the structure, fabricated a completely newstructure, and installed it on the VMS during ascheduled shutdown. The design upgradeimproved the strength in some known areas ofweakness and changed the flexible-joint de-sign to improve maintainability. Otherwise, theoriginal design configuration and geometry wereretained to capitalize on its proven success.

LATERAL-DRIVE GEAR RACKS

Grinding and alignment of the Lateral-Drivegear rack system involved removing the ap-proximately 40 linear feet of gear rack, sendingit out for precision grinding, and reinstalling itwith improvement in the gear mesh and align-ment. Again, this was a rework of an original,highly successful VMS design. The work cor-rected some dimensional deficiencies in thegear racks to allow improvement of the gearmesh and will extend the useful life of the gearsystem for several more years.