ADSLEV EL

Technical Memorandum 17-80

HELICOPTER IN-FLIGHT VALIDATION SYSTEM

(HELIVALS)

Thomas L. FrezellGordon HeraldoRichard S. Camden

Clarence A. Fry

August 1980AMCS Code 612716.H700011

-

C-,

ii. App~ov fo, pubic: urhms;_.Jdis.tibton unlimited.

U. S. ARMY HUMAN ENGINEERING LABORATORY

Aberdeen Proving Ground, Maryland

80 .G 21 09

i

Destroy this report when no longer needed.Do not return it to the originator.

The findings in this report are not to be construed as an official Departmentof the Army position unless so designated by other authorized documents.

Use of trade names in this report does not constitute an official endorsemcntor approval of the use of such commercial products.

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H ELICOPTR IN -FIH ORAANI ATION SYSTAND ADDRESS I* PORMEEET RJC A,

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US Army Human Engineering LaboratoryAberdeen Proving Groulnd, MD 7100l5 AMCMS Code 612716.117000l11

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I*. SUPPLEMENTARY NO0TES

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Data Collection Tn-Flight Aircraft lnstrlmentatiolInstrumented Helicopter Computer Anqlyqis Flipht Control Tionitnrinp

2. AuST'RAC? (CWamewee. elde Fneeev md ideruIEr by block ue)

6This report Jescribes the Helicopter In-Flight Validation System(HEL.IVALS). The Ryatem monitors all six degrees of freedom of the helicop-ter flight control position to include cyclic, collective and anti-torquepedials; along with airspeed, Altitude (both barometric and ahqolute), Andgeographic position. These data1 Are recorded digitally on a mapnetic taperecorder mounted in the helicopter. The recorded data is then proces-ted and >reduced in A ground Atat ion...

0O I0 if 13 EDtlOr Or MOV 6 Sis 00101. TE . - 2SECURITY CLASSIPICATION or rHis PAGE rm Veto Enot

AMCMS Code 612716.H700011 Technical Memorandum 17-80

HELICOPTER IN-FLIGHT VALIDATION SYSTEM

(HELIVALS)

Thomas L. FrezellGordon Herald

Richard S. CamdenClarence A. Fry

August 1980

9HN D. WEISZirector

U.S. Army Human Engineering Laboratory

U. S. ARMY HUMAN ENGINEERING LABORATORYAberdeen Proving Ground, Maryland 21005

Approwd for pubic reeem;digtrtbulhn unlimite.

CONTENTS

INTRODUCTION . . . . .. . . . . . . . . . .... 3

DISCUSSION. . . . . . . . . . . . . .. .. .. .. .. .. .. . .3

GROUND STATION.... . . . . . . . . . . . . . .*.. .. .. . .12

SUIMARY .... ..... . . . . . . .. .. .. . .. o .. .. . .17

APPENDIX

Analog and Digital Signals . ... . . . o. .. .. .. .. . .19

FIGURES

Frontispiece: J1JH1-H Helicopter .. .. .. .. .. .. .. .. 2

1. In-Flight Data Collection System Schematic .. .......... 4

2. In-Flight Data CollecSton.yste.. .. .. .. ...... 5 Al

3. Pilot's Radar Altimeter . .. .. .. .. .. .. .. .. . .7

4. Barometric Altitude and Airspeed Transducers .. ......... 8

5. Cyclic and Collective Transducers . . .. .. .. ... . . 9

6. Doppler Navigation/Telemetry Interface . . . .. .. .. .. 11

7. Pulse Code Modulation Data Paths . .. .. .. .. .. .. .13

8. Ground Station System Configuration . . .. .. .. .. .o 15

9. PlotFlgtest Daag.h. .. t. . t. . .. .. .. .. .. 16

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HELICOPTER IN-FLIGHT VALIDATION SYSTEM

(HELIVALS)

INTRODUCTION

The helicopter has become an integral resource to the US Army fieldcommander for mobility, surveillance, logistics, medical evacuation andfirepower. The utility of this battlefield resource is directly related tothe performance of the aviators who pilot the helicopters. This reportpresents the instrumentation techniques used by the US Army Human Engineer-ing Laboratory (USAHEL) to measure and analyze parameters pertinent to pi-lot performance.

The Helicopter In-Flight Validation System (HELIVALS) is part of themethodology employed to ascertain pilot performance and various experimen-tal conditions. The methodology consists of paper and pencil analysis fol-lowed by laboratory experimentation. The results of these techniques arefinally validated in-flight. The HELIVALS provides the experimental re-source needed to provide the objective in-flight validation data.

The HELIVALS measures, in real-time, the six degrees of freedom,flight control displacement, pitch, roll, rate-of-turn, aircraft accelera-tion, aircraft velocity, radar and barometric altitude, airspeed, andgeographic position in Universal Transverse Mercator (UTM) coordinates.The data are recorded on magnetic tape. The collected data are then tran-scribed and analyzed in ground station facilities located at the USAHEL.Growth potential allows for the real-time transmission of data through atelemetry transmitter to a ground station.

DISCUSSION

Airborne System Description

The system permits the simultaneous recording of analog, digital andsynchronous sensor data. The analog and synchronous data is converted todigital format while the digital data is recorded as it is generated. Thedata is then multiplexed and indexed with a time code generator. Thedigital data is recorded on an instrumentation tape recorder in Pulse CodeModulation (PCM) format. Figure 1 is a block diagram describing thesystem. A photograph of the data collection shown in Figure 2-.

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Sensors

Airspeed

Airspeed is obtained from a differential pressure transducer that isconnected to the aircraft's pitot and static lines. The pressure transduc-er has an output voltage of 0-5 volts which is calibrated with the air-craft's airspeed indicator to provide airspeed values proportional tothose seen by the pilot.

Altitude

Two types of altitude are recorded. Absolute, or radar, is the heightabove the earth's surface. Barometric is the altitude above mean sealevel.

Radar Altitude

The radar altimeter provides precise altitude above the terrain. Theaircraft is equipped with an AN/APN-209 radar altimeter which is calibratedto read 0 when the aircraft is sitting on the ground and can record to 1500feet above ground level. Figure 3 shows the pilot's radar altimeter.

Barometric Altitude

The barometric altitude information is processed through an altitudetransducer that is connected to the aircraft's static pressure line. Theeffective resolution is five feet with a recording capability from 0-10,000feet. The output of this transducer is calibrated to the aircraft's altim-eter. Figure 4 shows the pressure transducers for both barometric altitudeand airspeed.

Control Position

Control position is sensed through linear transducers connected to thepush rods of each of the respective controls (cyclic pitch, cyclic roll,collective, anti-torque pedals). The transducers provide +2-1/2" of travelwith 0-5 VDC voltage proportional to the control position. Low pass fil-ters with a 6HZ cutoff are used to eliminate undesirable high frequencyartifacts. Three of these transducers are shown in Figure 5.

Aircraft Position

The helicopter position is obtained with a Doppler Navigation System.The system installed is the Lightweight Doppler Navigation System (LDNS) orAN/ASN-128. The Doppler System is composed of three Line Replaceable Units

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The Doppler System is provided magnetic heading information from theaircraft's AN/ASN-43 magnetic heading reference system. Pitch and roll areprovided via the aircraft's MD-I reference gyro signal. This data is pro-vided in the form of three wire syncro signals plus a 26 VAC, 400-Hz refer-ence signal.

The accuracy of the Doppler Navigation System is highly dependent onthe accuracy of the associated heading reference system. The headingreference is the primary source of error in the Doppler Navigation System.Therefore, special emphasis and attention must be given to aligning andcalibrating the aircraft's AN/ASN-43 heading reference system.

A specially designed and constructed HEL interface is provided to se-lect any two out of the eleven possible Doppler Navigation data outputs andconvert them from serial Binary Coded Decimal (BCD) data to parallel BCDfor input to the Airborne Telemetry System. Generally, the logic will beset to provide UTH Easting and Northing data. Figure 6 is a block diagramof the Doppler Navigation/Telemetry interface which will be described in aseparate technical report.

Pitch and Roll

The pitch and roll positioning information is recorded directly fromthe altitude information available to the pilot on the MD-1 gyro. The MD-1is a single gyro with its spin axis stabilized in the vertical position.Two synchros, one on each gimbal of the gyro, have outputs proportional tothe pitch and roll angles. Theoretically, there would be no output fromthe pitch synchro if the nose of the aircraft moved laterally with respectto the earth while at a roll angle of 90 degrees. However, due to thelimited maneuverability of the aircraft, this presents no problem. Therotors of the synchros are excited with 110 VAC, 400 Hz from the aircraft'sinverters and this is used as the reference for the synchro-digital con-verters. The three-lead output from the synchros are taken through anadaptor, to be digitized and recorded.

Heading

Heading information is obtained from the auxillary synchro transmit-ter, B308, in the pilot's ID-998/ASN course indicator. This signal isslaved to the 3-2 gyro compass by a servo amplifier and motor which drivesthe pilot's heading dial and the rotor of the synchro. The J-2 gyro isslaved to magnetic north by a flux valve located in the tail of thehelicopter.

The three outputs from the synchro stator and the 26 volt, 400 Hzrotor excitation (reference) voltages are fed from an adapter, to the

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heading synchro/digital converter. An adapter similar to the one used onthe MD-i gyro was used for the ID-998 indicator in order to keep the air-crafts's wiring intact.

Angular Rates

A triaxial rate gyro is used to measure the instantaneous angularvelocities corresponding to roll, pitch and yaw. Each rate gyro is a DC-operated gimballess, type with 5,000 ohm potentimeter output with an accu-racy of +1 percent of full scale at zero degrees/second increasing to +2percent at maximum rate. The threshold is .5 percent of full scale. Thegyro spin motors require 28 volts DC +10 percent at a running current of300 ma. and a starting current of 2.5 mps maximum (starting time is ap-proximately 15 seconds). The overall weight is approximately 3.5 pounds.

This velocity transducer is aligned and affixed to a firm structure ofthe aircraft at a convenient location. The 0-5 volt DC output from thepotentiometer goes through a 6 Hz, low pass filter before entering themultiplexer-encoder.

Linear Acceleration

A hermetically-sealed, triaxial accelerometer with 5,000 ohm potentio-meter outputs is used to measure linear acceleration. These accelerometershave an accuracy (including linearity and hystereses) of +1 percent of fullscale at zero G's increasing to +2 percent of full scale at maximum loadfactor. Full scale range is +5 CPs with a 22 cps natural frequency. Theyweigh approximately 6 ounces.

Signal Conditioning

All linear transducer signals have low-pass filters with 6 Hz cutoffto eliminate undesirable high frequency artifacts.

GROUND STATION

Ground Station Hardware

A PDP-11/34A Computer hosts the ground-station telemetry hardwarewhich consists of an instrumentation tape recorder/reproducter, a PCMdecommutator, a time code translator, a buffered data channel interface,and a priority interrupt module.

The data paths are shown in Figure 7. Airborne data in serial PCMformat is reproduced from one of the tape recorder channels and passed tothe PCM encoder which processes the data stream to provide parallel data

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words to the buffered data channel interface. Concurrently, Inter-langeInstrumentation Group (lUIG) &-time code from a second tape-recorder chan-nel Is passed to a time-code translator which converts the IIG 3 code toparallel days, hours, minutes, and seconds and presents this data to thebuffered data channel to be merged with the PCH data. Sensor data and timeare then additionally processed in the PDP-11/34A Computer. Sensor datamay be plotted as it is processed with time Indexing and/or stored ondigital magnetic tape for later analysis.

Figure 8 depicts the entire ground-station system configuration andshows all the system peripheral and graphic devices available to the userfor data reduction, storage, transmission, and analysis. A high-speedcommunications line to a remote CDC Cyber 173/176 scientific computersystem is shown. It provides ready access to an exceptionally powerful toolfor data analysis.

Ground-Station Software

The ground-station hardware and the PDP-11/34 computer are integratedand controlled by the ground-station software which consists of the DEC RT-11 operating system and the Ern TELEVENT-11 software. Both software sys-tems are operated under license from the vendor.

TELEVENT is a real-tim, event-oriented software system designed foruse on PDP-11 computers which provides the operator with the capability toset up, acquire, process, and store data. This is accomplished through thefollowing functions:

a. Prepares the ground-station hardware and computer peripheraldevices to accept the incoming data.

b. Establishes paths for incoming data to the appropriate opera-tinS programs.

c. Acquires data in the form of a PCH stream from 12 digitalinputs, 32 analog inputs, and three time words, and stores this data in thePDP memory.

d. Processes data by converting to engineering units. Data isconverted by a user supplied polynomial transformation in the form:

y - sO+alz+a2x2+Q3 x3+a4 x4 +aSx5

a. Plot selected channels of data in stripchart form on theprinter/plotter. Up to 10 preselected channels can be plotted in real-timesimultaneously with data acquisition, conversion, and storage. Figure 9 isan example of several channels of data from a flight test which have beenplotted.

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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.. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........................ ............ . ..... ....

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....... . .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. ..

f. Formats and stores data on nine-track magnetic tape in ASCIIcharacters.

S. Provides the operator with the capability to connect/discon-nect interrupts to appropriate software programs.

Once the data has been received, processed, and stored on magnetictape, the RT-11 operating system can be utilized to process the datathrough analysis programs. Using FORTRAN under RT-1l, USAHEL can developanalysis programs for specific applications. In addition, if more complexdata analysis is required, the data can be transmitted to a remote CDCCyber 173/176 scientific computer system.

SUNMARY

The HELIVALS provides the USAHEL with a dynamic operational measure-ment tool to gather and validate in-flight performance measurements of Armyaircrew members. Such a research system provides the capability to obtainand validate data that often times is theoretical in nature. The HELIVALSallows the researcher to reach the final plateau in quantifying both air-craft performance maneuvers and pilot performance in a highly valid andversatile research tool. Such a system can only enhance the quality of theresearch product.

A summary table of the data collected is presented in the Appendix.

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APPENDIX

ANALOG AND DIGITAL SIGNALS

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Lot. Opll. 0-5" 0-3 SOC kPigisw falao V1edal 0 63 N 5 C - Tim historysimp"a"ams "Pt nw o044 f displaca-

I0m se.

Lass. Cyclic 0-5* 0-3 VIC position/ Goas. Modal 06 Ise 3 SC - Tim historybl,1amol PTl014-SA- of Laplace&-

100 ment.

Asti-Terigm 03. 0-5 S0C Palaial Go"". N"9dal 6 s3o 5 SDC - Tims historypedal Uslaoms P710143.- *f displute-

l00w Was.

Collective 0-10" 0-5 SC poasiaion Cass. Naol f 6 as S SC - Tino historybEopep~most PTlOI-3Z-0ak- of displace-

1000 sea.

Velocity -I +461Ss 0-5 INC Iblab Nmsqbray- 3 Ais 6 is S V/20 V - Ties historyamt - Roa of I-rate.

velocity - I +40/sa 0-3 INC %stab Ompbroy- 3 Ais 6 Us S V/RU V - Tias historyOM1 - Rate of T-rats.

Velocity 3 9 Whoo 0-5 INC vstob Nhmphrsy- 3 Auto 4 No 5 V/28 V - Tim hiotaryGyro - Rate of 2-rate.2002-336-1

Acslowaties, - it 45 aq 0-S SOC Lasco Nw.phroy- 3 hxis 6 on V - Tim history&coal - SA 700- of 1-Accel-0301-1 *ratio&.

LAcelersalo - I +5 as 6-3 INC "66s! Nwrsy- 3 Ais 6 n V - Ties history&coal - SA 700- of V-Ac.!-0301-1 *ratio".

LAtseates - N +5 ag 0-S SOC &eagse wsqhoy- 3 Ais No S v - Tims history

dustl - 1A 700- of 2-Acced-0301-1 dration.

Altitue - Sav. 0-1000 It 0-10 V Altitude etc 6 Me ±15 SDC - Tims history("wae adeser) Medal 0 am0 of altitude.

airspeed 3020M 1.5 V - 10 V airapeed 01C 6 No ±13 SDC - Tim historybeets CLOW atV 5 v "@1 0 oo of airspeed.

losses am 0"600ON 0-3 V 9 - Tim historyof swineRPH.

Altitude - RAAR 0-1900 It 00 11.1 V + Nhu2 13 we* - Ties history

.161 "w e t I "fEme111 M 150 efst altitude.

(OF ma. uase of sasheaItls. Guasp asipotat +3 v Jam. fastj)

Uaquhs Imener with 0.6 V offset. ±15 V onilable., iaquied har erfat ad otter circuit.buts, tadoeelewod ta single alt.

Wafitlasi" to 10 P'lOVded %I mmL.

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ANALOG SIGNALS

TransducerTransducer Transducer Manufacturer Excitation Channel Data

Signal Name input Range Output Range Type Transducer and Model Number Filter Voltage AssignmentdRequirement

lAt. Cyclic 0-5" 0-5 VDC Position/ Celesco Model # 6 Hz 5 VDC - Time historyDisplacement PT101-RX-5A- of displace-

lOOE sent.

Long. Cvcllc 0-5" 0-5 VDC Position/ Celescb Model # 6 Hz 5 VDC - Time historyDisplacement PTIOI-RX-5A- of displace-

lOOE sent.

Anti-Torque 0-" 0-5 VDC Position/ Celesco Model # 6 Hz 5 VDC - Time historyPedal Displacement PTIOI-RX-5A- of displace-

lOOE ment.

Collective (-10" 0-5 VDC Position/ Celesco Model # 6 Hz 5 VDC - Time historyDisplacement PTlO1-RX-lOA- of displace-

100C ment.

VecIcity - X +5°/sec 0-5 VDC Rateb

Humphrey- 3 Axis 6 Hz 5 V/28 V - Time historyGyro - Rate of X-rate.RG02-2356-1

Velocity - Y +5"/sec 0-5 VDC Rateb Humphrey- 3 Axis 6 Hz 5 V/28 V - Time historyGyro - Rate of Y-rate.RG02-2356-1

Velocity - 7 +5*/sec 0-5 VDC Rateb Humphrey- 3 Axis 6 Hz 5 V/28 V - Time historyGyro - Rate of Z-rate.RG02-2356-1

Acceleration - X +5 og 0-5 VDC AccelV Humphrey- 3 Axis 6 Hz 5 V - Time historyAccel - LA 700- of X-Accel-0301-1 eratton.

Acceleration - Y +5 og 0-5 VDC Accel€

Humphrey- 3 Axis 6 Hz 5 V - Time historyAccel - LA 700- of Y-Accel-0301-1 eration.

Acceleration - Z +5 og 0-5 VDC AccelO Humphrey- 3 Axis 6 Hz 5 V - Time historyAccel - LA 700- of Z-Accel-0301-i eration.

Altitude - Baro 0-10000 ft 0-10 V Altitude CIC 6 Hz +15 VDC - Time history(Press xducer) Model # 8000 of altitude.

Airspeed 30-200 1.5 V - 10 V Airspeed CIC 6 Hz +15 VDC - Time historyknots Clamp at 5 V Model # 8100 of airspeed.

Engine RPM 0-6600 RPM 0-5 V - Time historyof engineRPM.

Altitude - RADAR 0-1500 ft OV - 11.1 V a AN/APN-209 - +15 VDC5

- Time history.6V - zero feet of RADAR

11.1V 1500 feet altitude.(o means loss of trackcondition. Clamp outputat +5 V [628.6 feetl)

&Requires inverter with 0.6 V offset. +15 V excitation required for offset and inverter circuit.bRate transducer integrated in single t it.CAcceleration transducers integrated in single unit.dTo be determined by DIR.

'Signal conditioning to be provided by USAHRL.