I 

l- 

,_ a 

1- 

* 

JPL NO. 9950 - Id0 I c I 

I 

PnT- 4) 

w- 44373 8 

VOYAGER URANUS ENCOUNTER 

TEST REPORT 

0.24bf TNA SHORT PULSE 

86.R-1025 

Prepared for: 

Jet Propulsion Laboratory 

California Institute of Technology 

4800 Oak Grove Drive 

Pasadena, California 91 109 

January 17,1986 

m 

m 

\ 

I 

4N iz 
I 

!’ 

I. 

I 

1 

VOYAGERURANUSENCOUNTER 

0.2-lbf TNA SHORT PULSE TEST‘ REPORT 

(FINAL) 

Prepared for: 

Jet Propulsion Laboratory 

California Institute of Technology 

4800 Oak Grove Drive 

Pasadena, California 91 109 

Prepared by: 

Rocket Research Company 

A Division of ROCKCOR, Inc. 

11441 Willows Road N. E. 

Redmond, Washington 98052-1012 

JPL Contract No: 957308 

RRC Report No.: 86-R-1025 

Date: January 17, 1986 

Prepared and approved by: 

D. R. Johnso; 

Project Manager 

THIS REPORT DOES NOT IDENTIFY “NEW TECHNOLOGY” ITEMS. 

’Ihir work was pcrforwd for the Jet Propulsion Laboratory. California Institute of 

Tcchrrdgy. spmorcd by the NaW kroorutia lad sp.cC Mminiru.lioa. 

Rcfmncc hacin to any specific commcrial product. process. a service by trade nunc. 

trademuk. mmufuturcr, or otherwise. docs not constitute or imply iu endorsement by thc 

United State Gownunrnt. the Rocket Rercuch Company, or the Jet Propulsion 

Laboratory. California Inrticute of Tahaolgy. 

i 

. 
ABSTRACT 

I 

1 

The purpose of this test program was to determine if the attitude control thrusters on the 

Voyager spacecraft can be operated at electrical pulse widths of less than the current 10- 

millisecond minimum in order to reduce impulse bit and, therefore, reduce the image 

smear of the pictures to be taken during the Uranus encounter. Thrusters with the 

identical configuration of the units on the spacecraft were fired in an altitude chamber to 

characterlze impulse bit and impulse bit variations as a function of electrical pulse widths 

and to determine' if the short pulses decreased thruster life. Pulse widths of 4.0 

milliseconds provide approximately 45 percent of the impulse provided by a 10-millisecond 

pulse, and thruster-to-thruster and pulse-to-pulse variation is approximately plus or minus 

10 percent. Pulse widths shorter than 4 ms showed wide variation, and no pulse was 

obtained at 3 ms. Three thrusters were each subjected to 75,000 short pulses of 4 

milliseconds or less without performance degradation. A fourth thruster exhibited partial 

flow blockage after 13,000 short pulses, but this was attributed to previous test history 

and not short pulse exposure. The Voyager attitude control thrusters should be considered 

flight qualified for short pulse operation at electrical pulse widths of 4.0 milliseconds or 

. 

.* 

1 

I greater. 

\ 

XD/287 
I 

' 

t 

i 

1108S31B 
TABLE OF CONTENTS 

Section 

1.0 

2.0 

3. 0 

4.0 

5.0 

PaRe 

ABSTRACT ii 

SUMMARY .......................... 1-1 

1.1 Purpose ......................... 1-1 

1.2 Results ......................... 1-2 

.. 1.3 Conclusions ........................ 1-2 

TESTPLAN ......................... 2-1 

2.1 TestUnitSelection ..................... 2.1 

2.2 Propellant UsedforTesting ................ 2-1 

2.3 TestFlowPlan ..................... 2-2 

2.4 . FunctionalTests ..................... 2-2 

2.5 Characterizationlests .................. 2-2 

2.6 Short Pulse Width Tests .................. 2-7 

2.7 AbbreviatedLifeTcst .................. 2-8 

TESTSETUP ......................... 3-1 

3.1 TestFiringFixture .................... 3-1 

3.2 Testcell ........................ 3-1 

3.3 Instrumentation ..................... 3-1 

3.4 DataReduction ..................... 3-11 

TESTRESULTS ........................ 4-1 

4.1 General ......................... 4-1 . 

4.2 

4.3 

Determination of Impulse Bit as a Function of Electrical 

Pulsewidth ....................... 4-1' 

Determination of Pulse-to-Pulse Impulse Bit Variations 

as aFunaionof Electrical Pulse Width ........... 4-14 

4.4 ThrusterLife ...................... 4-14 

4.5 TypicalPulseShapes ................... 4-26 

4.6 Functionallests ..................... 4-26 

4.7 HardwareFailures .................... 4-26 

CONCLUSIONS. ........................ 5-1 

APPENDIXA-Hydrazine Analyses ............... A-1 

XD/287 iv 
. 

LIST OF FIGURES 

Figure Page 

2-1 

2-2 

2-3 

3-1 

3-2 

3-3 

3-4 

3-5 

34 

3-7 

3-8 

4-1 

4-2 

4-3 

4-4 

4-5 

4-6 

4-7 

4-8 

4-9 

4-10 

Voyager 0.2-lbf T/VA Short Pulse Test Flow Plan 

First25. 000Pulxs ...................... 2-3 

Voyager 0.2-lbf T/VA Short Pulse Test Flow Plan 

Voyager 0.2-lbf T/VA Short Pulse Test Flow Plan 

Third25. 000Pulxs ...................... 2-6 

0.2-lbf T/VA Short Pulse Test Firing Setup ............ 3-2 

0.2-lbf T/VA ShortPulseTest Firingsetup ............ 3-3 

0.2-lbf T/VA Short PulseTest Setup ............... 3-4 

Se~0nd25. OOOPUISCS ..................... 2-4 

T/VAFiringTestSetup .................... Automaticlest ControlSystem ................. ATCSBlockDiagram ..................... Digital Data AcquisitionSystem ................ High-speed Digital Datasystem Block Diagram .......... Short Pulse Test 1 . Impulse Bit Versus Electrical Pulse 

Width ............................ Short Pulse Test 5 . Impulse Bit Versus Electrical Pulse 

Width ............................ Short Pulse Test 8 . Impulse Bit Versus Electrical Pulse 

Width ............................ Short Pulse Test 1A . Impulse Bit Versus Electricd Pulse 

Width.,. .......................... Short Pulse Test 6A . Impulse Bit Versus Electrical Pulse 

Width ............................ Short Pulse Test 12A . Impulse Bit Versus Electrical Pulse 

Width ............................ Short Pulse Test 1 . Average Impulse Bit of Three Test REA's 

Versus Electrical Pulse Width .................. Short Pulse Test 5 . Average Impulse Bit of Three Test REA's 

Versus Electrical Pulse Width .................. Short Pulse Test 8 . Average Impulse Bit of Three Test REA's 

VersusElectticalPulseWidth .................. Short Pulse Test 1A . Average Impulse Bit of Three Test REA's 

Versus Electrical Pulse Width .................. 

3-5 

3-7 

3-8 

3-9 

3-10 

4-2 

4-3 

4-4 

4-5 

4-6 

4-7 

4-8 

4-9 

4-10 

4-11 

XD/287 V 
Finure 

LIST OF FIGURES 

(Concluded) 

PaRe 

4-1 1 

4-12 

4-13 

4-14 

4-15 

4-16 

4-17 

4-1 8 

Short Pulse Test 6A . Average Impulse Bit of Three Test REA% 

Versus Electrical Pulse Width .................. 4-12 

Short Pulse Test 12A . Average Impulse Bit of Three Test REA's 

VersusElectricalPulse Width .................. 4-13 

4-15 

Average iit as Percent of Ibit at EPW = 10 msec for 3 .. TestREA .......................... 4-16 

Short Pulse Test 1 . Pulse-to-Pulse Impulse Bit Variation 

Versus Electrical Pulse Width .................. 4-17 

Short Pulse Test 5 . Pulse-to-Pulse Impulse Bit Variation . Versus Electrical Pulse Width .................. 4-18 

Short Pulse Test 8 . Pulse-to-Pulse Impulse Bit Variation 

Versus Electrical Pulse Width .................. 4-19 

Short Pulse Test 1A . Pulse-to-Pulse Impulse Bit Variation . Versus Electrical Pulse Width .................. 4-20 

AverageIbit At EPW = IO mxcfor 3 Test REA's ......... 

4-19 

4-20 

4-2 1 

4-22 AverageImpulxBit Versus AccumulatedLife .......... 4-25 

4-23 ...... 4-27 

Short Pulse Test 6A . Pulse-to-Pulse Imulse Bit Variation 

Versus Electrical Pulse Width .................. 4-21 

Short Pulse Test 12A . Pulse-to-Pulse Impulse Bit Variation 

Versus Electrical Pulse Width .................. 4-22 

Average Impulse Bit of Three Test REA's Versus Accumulated 

Life ............................ 4-24 

Short Pulse Test 1 . REA S/N 016. Pulse 10. PF . 220.0 

LIST OF TABLES 

. Table Pane 

2-1 T/VA Characterization Test Duty Cycle ............. 2-7 

2-2 Short Pulse Width Test Duty Cydes ............... 2-7 

2-3 AbbreviatedLifeTest Duty Cydes ............... 2-8 

3-1 Test Instrumentation ........ ' ............. 3-6 

4-1 CharacterizationTest Summary ...... : .......... 4-23 

4-2 T/VA GN2andValveResponseTests ............... 4-28 

XDl287 vi 
This report documents the short pulse width testing completed on the Voyager 0.2-lbf 

thruster valve assemblies (T/VA's) under the Jet Propulsion Laboratory contract number 

957308. The initial testing was performed under JPL contract 956930 and some of the 

information is included in this report to preserve continuity. The testing was conducted at 

Rocket Research Company, Redmond, Washington, in October 1984 through April 1985 

and July 1985 through November 1935. 

1.1 PURPOSE 

1.1.1 Bad<ground 

The Voyager 2 spacecraft will pass by Uranus on January 24, 1986. During a 6-hour period 

of close encounter, high resolution phwographs will be taken of the planet and its moons 

and rings. In order to get quality pictures of these dimly lit objects, the Voyager's cameras 

will have to track these objects with their shutters open. This technique involves rotation 

of the entire spacecraft aird requires very precise control to prevent "image smear". This 

control is provided by a computer and the 0.2-lbf thruster valve assemblies (T/VAP) built 

there is less light, the camera exposure time is longer, making image smear more of a 

problem. 

( 

r by RRC. Since Uranus is much farther from the sun than Jupiter or Saturn and therefore 

I 

In order to help solve this problem, it is desireable to fire the T/VA's using shorter pulses 

than the standard minimum pulses and therefore reducing the rate of spacecraft 

movement. 

1.12 Scope 

The purpose of this test program was to determine if the thruster valve assemblies (TVA's) 

can be successfully and repeatedly fired at pulse widths of less than the standard 

minimum pulse width of 10 milliseconds. The goal was to demonstrate that the TVA's can 

be successfully fired using a pulse width that will produce an impulse bit of 10 to 50 

percent of the impulse of a 10-millisecond pulse without effecting thruster life. 

XD/287 1-1 
The objectives of this test program were to determine .I) impulse bit as a function of 

electrical pulse width, 2) impulse bit variations as a function of electrical pulse width, and 

3) determine if the short pulses decrease thruster life, Thruster valve assemblies (T/VA's), 

identical to the units on the spacecraft, were tested to determine these objectives, and 

the results of the testing is contained in this report. 

j 

1.2 RESULTS 

A pulx width of 4.0 millisecond was determined to the minimum acceptable pulse, It 

provides an impulse bit of approximately 45 percent of the impulse provided by a 10 

millisecond pulx and the pulse-to-pulse and unit-to-unit variation is approximately plus or 

minus 10 percent. A 3.5 millisecond pulse is unsuitable because of the wide pulse-to-pulse 

variation and at a pulse width of approximately 3.0 milliseconds no impulse is obtained. 

Seventy-five thousand (75,000) short pulses of 4 milliseconds and shorter cause no 

performance degradation. Three units showed no effect, One unit exhibited partial flow 

reduction after 13,000 pulses but this is attributed to the previous testing history. 

., 

1.3 CONCLUSIONS 

There is no significant risk associated with short pulse operation. This is supported by: 1) 

a successful demonstration test program was completed, 2) 410,090 pulses were accumulated on one T/VA during the Voyager qualification test, and 3) 75,000 short pulses 

represents less than 1 percent of the qualified hydrazine throughout capability. 

The Voyager T/VA's should be considered flight qualified for short pulse operation at pulse 

widths of 4 milliseconds or greater. 

i 

XD/287 1-2 
2.0 TESTPLAN 

21 TESTUNITSELECTION 

Five thruster valve assemblies (TVA's), four prime, and one backup were selected from the 

Voyager (MJS) program residual hardware. These units are identical in configuration to 

the units on the Voyager spacecraft. The previous firing histories of the test TVA's 

bracketed the firing histories of the flight units. The test TVA's and their firing histories 

are listed below: 

. 

Pulses On-time (sec) Remarks .. S/N 

016 9,555 1,211 Prime 

019 2,965 426 Prime 

020 2,530 86,300 Prime 

022 120,189 58,082 Prime 

02 1 37,057 1,269 Backup 

All of the TVA's successfully completed the initial functional testing. 

The four prime TVA's (S/N 016, 019, 020, and 022) were subjected to -he initial 

characterization test. The characterization test duty cycle is equivalent to the original 

acceptance test duty cycle. The four TVA's successfully completed this test, meeting all 

of the original acceptance test criteria. If one of the four units had not met the original 

acceptance test requirements it would have been replaced with the backup unit, S/N 021. 

22 PROPELLANT USED FOR TESTING 

The propellant used throughout this test program was of high purity grade hydrazine from 

drum number H-8300 furnished by the Jet Propulsion Laboratory. This hydrazine is of the 

same quality as used on the Voyager spacecraft and also meets the specification 

requirements for Viking, MMC, and high purity grade MIL-P-26536, Amendments 1 and 2. 

The hydrazine in drum number H-8300 was analyzed at JPL prior to shipment to RRC and 

found to meet the Voyager requirements. The hydrazine in the drum was analyzed at RRC 

and found to meet the requirements of high purity grade and Voyager hydrazine. The 

XD/287 2- 1 
propellant system of test cell number 4, the test cell in which the short pulse testing was 

performed, was filled from hydrazine drum number H-8300. The hydrazine in the 

propellant system was analyzed and found to meet all of the requirements. An analysis of 

the hydrazine in the system was performed several times during and at the completion of 

the test program; and in all cases, the requirements were met, The detailed hydrazine 

analyses are contained in Appendix A. 

23 TEST FLOW PLAN 

The test flow plans of Figures 2-1, 2-2, 2-3 and 2-4 delineates the testing and test 

sequencing of the entire test program. 

The overall test flow plan is described in Figure 2-1. This plan shows the sequencing of the 

characterization and short pulse tests performed over the 75,000 short pulse life testing. 

The test flow plans of Figures 2-2, 2-3, and 2-4 describe the testing in more detail and 

show the test sequencing for the first, second, and third 25,000 life test pulses 

respectively. 

Specific details of the tests presented in these flow plans are described in the following 

sections. 

( 

24 FUNCTlONALlE!5TS 

The thruster valve assemblies (TVA's) were subjected to the following functional tests: 

0 

0 TVA gas (GN2) flow 

0 Internal and external leakage 

0 Thruster heater resistance 

0 

Thrust control valve opening response 

Proof pressure (before and after first 25,000 pulses only) 

The purpose of these tests was to 1) determine the TVA acceptability for the test 

program, 2) establish a functional baseline, and 3) verify functional performance after 

25,000 and 75,000 pulses. 

25 CHARACTERIZATION TESTS 

The characterization test duty cycle is described in Table 2-1 and is representative of the 

original acceptance test. 

XD/287 2-2 
i 

, 

! 

I @@ 

(00 

I@@ 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

-I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

00 

11 17559 2-3 Figure 2-1 
1 

c;r 

0 

1115447B Figure 2-2 

24 
1117355 Figure 2-3 

2-5 
t 

z 

n 

9 

B 

s 

U 

a 

a 

w 

Q 

> 

0 

> 

i 

11 172-56 

2-6 f igum 2-4 
Table 2-1 

TNA CHARACTERIZATION TEST DUTY CYCLE 

Off 

Time 

t=) 

3.98 

0.90 

- 

Propellant 

Fed hum Test 

Scquence @si3 

Initial 

Temp. 

t OF) 

325 f 25 

Existing 

Existing 

350 f 5 

350 f 5 

350 f 5 

I 150 f 5 4 

n102yol) 

No. 

of 

Pulses 

100 

20 

1 

1 

On 

Time 

t=) 

0.020 

0.10 

200 

200 I Existing 1 - 

The purpose of the characterization tests was to 1) determine the acceptability of the 

thruster valve assemblies OVA'S) for the test program, 2) establish TVA baseline 

performance, and 3) verify acceptable TVA performance after each 25,000 pulses. 

26 SHORT PULSE WIDTH TESTS 

The short puke width test duty cycle is presented in Table 2-2. (, 

Test 

No. 

1 

2 

3 

4 

5-8 

1A-12A 

Table 2-2 

SHORT PULSE WIDTH TEST DUTY CYCLES 

Propellant 

Feed Pressure 

(psi.) 

m*5 

m*5 

190 f 5 

190 * 5 

m*5 

m*5 

No. 

of 

PUlsrS 

10 ea 

10 ea 

10 ea 

10 ea 

10 ea 

5ea 

10, 9, 8, 7.5, 7,6.5, 6, 5.5, 5, 

4.5.4.3.5, 3 

3, 3.5.4, 4.5, 5, 5.5, 6, 6.5, 

7,7.5,8, 9, 10 

10, 9, 8, 7.5, 7,6.5, 6, 5.5, 5, 

4.5,4.3.5, 3 

3. 3.5.4.4.5, 5, 5.5, 6, 6.5, 

7, 75,8.9, 10 

10, 8.6, 5, 4.5,4, 3.5, 3, 3, 

3.5.4.4.5, 5, 6, 8 

10, 8.6. 5, 4, 3.5, 3 

Off 

Time 

(=I 

60 

60 

60 

60 

60 

30 

Initial 

Temp. 

(OF) 

325 f 2s 

325 f 25 

325 f 2S 

325 f 25 

325 f 25 

Both 

heatas on 

2-7 
The purpose of the short pulse width tests was to 1) establish a curve of impulse bit as a 

function of electrical pulse width, 2) determine impulse bit variations as a function of 

electrical pulse width, and 3) monitor TVA performance after each 5,000 pulses. 

TCS~ TNA TNA 

No. SIN 16 SIN 19 

2.7 ABBREVIATED LIFE TEST 

The abbreviated life test duty cyde is described in Table 2-3, and the electrical pulse 

width (on-time) represents an impulse bit that is 25 to 30 percent of the impulse bit of a 

10-millisecond pulse. The "on-times" were determined from the curves generated by the 

short pulse width tests. 

T/VA TIVA TIVA 

SIN 22 SIN u) SIN 21 

The purpose of this test was to determine the effect of 75,000 short pulses on thruster 

2 

3 

4 

1A-1OA 

life. 

4.0 4.0 4.0 4.0 - 

3.6 3.7 3.7 3.8 - 

3.6 3.7 3.7 3.8 - 

3.6 3.7 3.7 - 10.0 

Table 2-3 

ABBREVIATED LIFE TEST DUTY CYCLES 

TeSt 

No. 

1A - IO.. 

RlOWD7) 

XD/287 

Propellant 

Feed Pressure 

(psis) 

220 It 5 

220 f 5 

220 * 5 

220 f 5 

220 * 5 

No. 

of 

Pulses 

*On Time (milliseconds) 

Off 

Time 

30 

30 

30 

30 

30 

1 1 3.3 I 3.5 I 3.4 I 3.5 I - I 

Thruster 

Temp. 

(OF) 

325 f 25 

325 2 25 

325 & 25 

325 f 25 

Both 

heaters on 

2-8 
3.0 TEST SETUP 

3.1 TEST FIRING FIXTURE 

The four thruster valve assemblies (T/VA's), S/N% 016, 019, 020, and 022, were installed 

on the test firing fixture as shown in Figures 3-1, 3-2 and 3-3. 

Thermocouples were welded to the convergent section of the thrust chamber nozzle in 

order to provide thrust chamber temperature measurements. In order to provide thrust 

chamber pressure measurements the T/VA chamber pressure (P,) tubes were connected to 

JPL-furnished Taber pressure transducers using specially prepared adapters to redice the 

holdup volume. Transducers with a range of 0 to 300 psia were used for the characterization tests and transducers with a 0 to 50 psia range were used for the short pulse width 

and abbreviated life tests. 

33 TESTCELL 

The test cell setup is shown schematically in Figure 3-4. 

The schematic shows the propellant system, pressurization system, propellant thermal 

conditioning system, water decontamination system and the altitude chamber. The 

altitude chamber will maintain an altitude of 200,000 feet minimum and much higher in 

most cases. 

3.3 INSTRUMENTATION 

The test parameters to be measured, calibration ranges, and method of recording data are 

listed in the test instrumentation Table 3-1. 

The Automatic Test Control System (ATCS) is used to control the testing utilizing a 

preprogrammed disc. The ATCS is presented in Figures 3-5 and 3-6. 

The Digital Data Acquisition System (DDS) is used to collect the high speed digital data 

and store it on magnetic tape. The DDS is presented in Figures 3-7 and 3-8. 

I 

l 

Test instrumentation calibrations were performed to secondary standards traceable to the 

National Bureau of Standards. An accurate time base for the electrical pulse signal was \ 

i XD/287 3-1 
OF 'OR QuAuTy0.2 Ibf TNA SHORT PULSE TEST FIRING SETUP 

ORIGML PACE @ 

OF POOR QUAUW 

1 1 165-90 28594 3-2 Figure 3-1 

\ 
11 165-91 2859-3 3-3 Figure 32 
11 16592 2859-2 34 Figure 3-3 
4 

t; 

v) 

t 

;f 2 

I 

11 148-84A 

I 

3 

3 

> 

Y 4 

a. 

c 

a I 0 

35 Figure 34 
Parnmeter 

Table 3-1 

TEST INSTRUMENTATION 

Recording Technique 

Chamber pressure - Thruster 

Propellant feed pressure 

Propellant temperature 

Altitude chamber pressure 

Sightglass level 

Valve voltage 

Valve current 

Thruster heater voltage 

Thrust chamber .temperature 

Symbol Range 

0 - 300 psia 

and 

0 - SO psia 

0 - 400 psig 

O-Smv 

0 - 1 psia 

N/A 

0 - 30 Vdc 

3 - 0.25 amps 

0 - 30 V~CO-5Omv 

DDS 

X 

X 

X 

X 

Manual 

X 

X 

- 

X 

3-6 
AUTOMATIC TEST CONTROL SYSTEM 

. . . . . . . . . , . .-. e . .. ..e... 

00000000 

1 1 152-87 2227-3 3-7 Figure 35 
t 

U 

J 

U 

E 

a 

u 

I- 

- 

-. 

1114840 3-8 Figure 3-6 
-- 

DIGITAL DATA ACQUISITION SYSTEM 

i-I 

*. ... .,, .. c 

I. ... . . .. .* 

- /. . 

1 1 152-88 2480-2 3 -9 Figure 3-7 
HIGH-SPEED DIGITAL DATA SYSTEM 

TEST DATA 

BLOCK DIAGRAM 

OPE RATOR 

- 

A/D 

IN - 

TE RFACE 

I MUX 

. . . . . . . . CORE . . . . . . . . . NOVA lz00 COMPUTER ' MEMORY I I I 

STARTBTOP MAGNETIC 

b TAPE 

e ADAPTER MTU ~ 

CONTROLLE R 

IN - 

TERFACE I 

MAGN ETlC 

I I 

DISABLE START KEY: ' 

0 ANALOGDATA 

e DIGITAL DATA 

_I+ CONTROL SIGNALS 

- STATUS SIGNALS 

( 

MAGNETIC 

DATA TAPE 

, ,11148-89 

1. .. 3-10 Figure 38 
i difficult to obtain because the Automatic Test Control System (ATCS) was designed to 

operate at one millisecond intervals and this testing required control of the electrical 

pulse in one-tenth of a millisecond intervals. In order to accomplish this the ATCS was 

modified to speed up the time base electronically by a faaor of ten; Le., for each one 

second of real time the ATCS time base registers 10 seconds. Therefore, a 35 millisecond 

input to the ATCS would result in a 3.5 millisecond output command to the valve drivers. 

The ATCS output pulse width commands were calibrated. The pulse widths had a tendency 

to drift and had to periodically be recalibrated. 

3.4 DATA REDUCTION 

The raw test data contained on the DDS magnetic tape is processed on a computer that 

has been programmed to reduce the raw data into engineering data such as impulse bit 

(Ibit) and specific impulse (I 1. This data is then displayed on computer printout sheets. 

SP 

The following is a summary of the equations used in the computer program MJSDAT. 

0 a = (0.641667E-05) + (0.229905E-08)T - (0.104312E-1 1)T2 + (0.3763OE-lS)T3 

where: 

- 

where: 

the coefficient of thermal expansion for Haynes 25, in/in/% * IO6 

measured nozzle temperature, OF. 

corrected throat area, sq. in. 

measured throat area, sq. in. 

the coefficient of thermal expansion for Haynes 25, in/in/% * lo6 

measured nozzle temperature, OF 

discharge coefficient = 0.9986 

0.0222886 0 Cfss = 1.55023 * Pc 

where: 

= steady-state thrust coefficient. =fsS 

Pc = measured chamber pressure, psia 

XD/ 287 3-1 1 
0006896 /Pcdt 1/(23.07 + 0.0093681 * T)) = 3.178/(T f Pm 

OC 

where: 

= pulse mode thrust coefficient fPm 

C 

T = chamber temperature, OF 

jPcdt = time integral of chamber pressure, psia-sec 

where: 

= steady-state vacuum thrust, Ibf 

= chamber pressure, psia 

= corrected throat area, sq. in. 

= steady-state thrust coefficient 

FV 

pC 

Cfss 

where: 

= pulse mode impulse bit, lbf-sec 

/Pcdt = time integral of chamber pressure, psia-sec 

= corrected throat area, sq. in. 

= pulse mode thrust coefficient 

'bit 

f Pm 

C 

RHO = 8.70038 - (0.4114llE-O2)T 

where: 

RHO = density of 99% Hydrazine, Ibm/gal 

T = propellant temperaure, 4: 

tk = RHO * K D/(T 3785.4) 

where: 

* = steady-state propellant flow rate, lbm/sec 

RHO = density of 99% Hydrazine, Ibm/gal 

K = sightglass calibration constant, cc/cm 

D = observed propellant drop in sightglass, cm 

T = time that sightglass valve was open, sec. 

XD/287 3-1 2 
I 

0 Wp = RHO K * Dl(3785.4 N) 

where: 

W = per pulse propellant consumption, lbm 

RHO = density of 99% Hydrarine, lbm/gal. 

K = sightglass calibration constant, cc/cm 

D = observed propellant drop in sightglass, cm 

N 

P 

= number of pulses over which drop in sightglass level is observed 

where: 

I = steady-state specific impulse, lbf-sec/lbm 

* = steady-state propellant flow rate, lbm/sec 

= steady-state vacuum thrust, lbf spSs 

FV 

where: 

I = pulse ode specific impulse, Ibf-sedlbm 

'bit 

P 

= pulse mode bit, lbf-sec 

-W = pulse propellant consumption, lbm 

SPp!ll 

0 CIISs = Pc it A.tc g/* 

where: t 

= steady-state characteristic velocity, ft/sec 

= chamber pressure, psia 

= 

=*Ss 

pC 

corrected throat area, sq. in. 

g = gravitationai constant = 32.174 f t/sec/sec 

6 = steady-state propellant flow rate, lbm/scc 

0 C* = fPcdt* Atc*g/Wp Pm 

where: 

= 

= pulse mode characteristic velocity, ft/sec 

time integral of chamber pressure, psia-sec '*pm 

.fPcdt 

XD/287 3-13 
= corrected throat area, sq. in. 

B = gravitational constant = 32.174 ft/sec/sec 

W = pulse propellant consumption, lbm 

P 

In addition, the following relationships are true: 

0 TI = response time from valve-on signal to 10% of the average chamber 

pressure, msec. 

response time from valve-on signal to 90% of the average chamber 

pressure, msec. 

decay time from valve-off signal to 10% of the average chamber 

pressure, msec. 

TR 

TD 

= 

= 

where the average chamber pressure is the peak chamber pressure attained for 

pulse widths less than 60 milliseconds, and is the average chamber pressure at 500 

milliseconds after valve-on signal for steady state firings. 

0 The time of integration for all pulses fired in the short pulse test duty cycles is the 

time from valve-on signal to the time of the valve-off signal plus 6 seconds. 

XD/287 3-14 
4.0 TESTRESULTS 

! 

4.1 GENERAL 

The test results presented herein do not include the results of every test due to the 

copious amount of data generated by this test program. The results presented are clearly 

sufficient to fulfill the requirements of the purpose and scope of this program. The Jet 

Propulsion Laboratory has been furnishtd copies of all of the computer data and RRC has 

the original data and copies on file. 

The short pulse test results have been limited to short pulse tests l,.S, 8, lA, 6A and I2A. 

These tests are representative of the entire test program including the start and finish. In 

some cases the results of T/VA S/N's 020 and 021 have been ommitted, especially when an 

average of the T/VA's is used. In this case an average of three T/VA's, S/N's 016, 019 and 

022, is used to plot the results. The reason T/VA S/N 020 is not included is because of 

partial flow blockage after 13,000 pulses (this problem was due to previous firing history 

and not short pulse test exposures). T/VA S/N 021 was installed in place of S/N 020 after 

25,000 short pulses but was not included in the averaged data because it was not subjected 

to short pulses of 4 milliseconds or less during life testing. S/N 021 was operated at a 

standard duty cycle of 10-millisecond pulses. 

( 

The overall test-to-test curve shift of the short pulse test presentations is due to the 

slight drift of the ATCS pulse command signal. This signal was calibrated periodically. 

< t 

4.2 

4.21 

Curves of impulse bit versus electrical pulse width for the individual T/VA's are presented 

in Figures 4-1 through 4-6; short pulse tests 1,5, 8, lA, 6A and 12A respectively. 

DETERMINATION OF Ih4PULSE BIT AS A FUNCTION OF ELECTRICAL 

PULSE WIDTH 

Impulse Bit as a Function of Electrical PSe Width 

Curves of the average impulse bit of the three T/VA's S/N 016, 019 and 022 versus 

electrical pulse width arc presented in Figures 4-7 through 4-12; short pulse tests 1, 5, 8, 

lA, 6A and 12A respectively. 

XD/287 4- 1 
u) 

t 

B 

cp 

t 

6i 

u) 

a 

0) 

B 

0 

B 

. v) 

(v 

8' 

(P 

CJ 

Q 

. ID 

c 

0 

a L m 

m a CD 

0 

Figure 4-1 
n 

v) 

0 

Z 

0 

0 

W 

v) 

H 

J 

J 

H 

z 

U 

I 

Io 

H 

x 

W 

w 

J 

3 

Q, 

J 

u 

H 

0 

W 

J 

W 

a 

C 

C 

B 

Figure 42 
i 

3 

ai 

8 * 

6 

la 

m 

6 

. 

Figure 4-3 

Ld 

t 

5 

3 

a' 

W 

n 

5 

rn 

n 

0 

N 

. 

tv) 

LLJ 

tu 

v) 

J 

1 

a 

Figure 4-7 C33S-387) 001 X 11a 3SlndWI 

4-8 
ai 0 B 

001 x im 

4-9 

ai ai 

3s 7nd W I 

8 

Figure 48 
/ 

i 

et- 

- 

a s' e a a 

4-10 Figure 4-9 
3 

a B' cp 

8 

c Ld 

c 

3SlndWr 

d 

a 

ai 

Figure 4-10 
e- 

- 

- 

e . e e 

B 8' e 6 ti a' a 0 ai CI 6 

cms-~am 001 x 1r0 3sind~r 

4-12 Figure 4-1 1 
. .i 

4-13 Figure 4-12 
\ 4.22 

Curves of impulse bit as a percent of the impulse bit of a IO-millisecond pulse are 

presented in Figures 4-13 and 4-14. These curves represent the average of the three test 

T/VA's S/N 016, 019 and 022. Short pulse tests 1, 5, and 8 are presented in Figure 4-13 and 

short pulse tests IA, 6A, and 12A are presented in Figure 4-14. 

Impulse Bit as a Percent of the Impulse Bit of a IO-Millisecond Pulse 

4.3 DETERMINATION OF PULSE-TO-PULSE IMPULSE BIT VARIATIONS AS A 

FUNCTION OF ELECTRICAL PULSE WIDTH 

Plots of pulse-to-pulse impulse bit variations versus electrical pulse width are presented 

in Figures 4-15 through 4-20; short pulse tests 1, 5, 8, lA, 6A and 12A respectively. 

Five short pulses were performed at each data point. The pulse-to-pulse variations was 

determined by taking the difference between the highest and lowest impulse bit of the 

five pulses and dividing by the average. 

The maximum pulse-to-pulse variation occurs at 3.5 milliseconds and decreases dramatically as the pulse width increases. 

( 4.4 THRUSTER LIFE 

4.4.1 Characterization Tests 

The characterization test summary in Table 4-1 presents the performance of the T/VA's 

at several points throughout the 75,000 pulse life testing. 

There was no significant performance change throughout the life testing except in the 

case of T/VA S/N 020. This T/VA experienced partial flow blockage after 12,000 pulses ' 

but this is attributed to previous firing history and not the exposure to short pulse testing. 

- 

4.4.2 Short PSeTests 

The short pulse test plots of impulse bit versus accumulated life is presented in Figures 

4-21 and 4-22. Figure 4-21 is a plot of the average of the three T/VA's S/N 016, 019 and 

022 and Figure 4-22 is a plot of the individual T/VA's including serial number 020. 

There is no significant change in impulse bit throughout the life testing. The test-tetest 

variation is due to the slight drift of the ATCS pulse width command signal. 

XD/287 4-14 
33SH 0l=Md3 LV LI8 3SlndWI JO lN33a3d 

4-15 Figure 4-13 

c. 

tDL 

0 

T 

w 

4 

W 

(41 

LL 

1 

I 

N 

a, 

m 

'B 415 
i 

\ 

C33N3d3ddICJ %> NOIIVIWA 1M 3SlndWI 

4-18 Figure 4-16 

P 

n Lp 

e 

Figure 4-18 

.. la n 

e 

CI 

la - 8 

L 

u) 

C33N32i33dIU K> NOIIVIWA 118 3SlndWI 

4-22 Figure 420 

cp 

W 

B' 

Figure 4-21 
i 

,. 

8 

I- 

$ 0 

U 

cn 

3 

W 

> 

IH 

W 

z 

m 

Y 

z 

H 
i 4.5 TYPICAL PULSE SHAPES 

Curves of thruster chamber pressure versus time for pulses with electrical pulse widths of 

3.5 to 10 milliseconds are presented in Figure 4-23. Note the delay in chamber pressure 

indication and the long tailoff. 

4.6 FUNCTIONAL TESTS 

All of the initial functional tests were satisfactory and there was no significant functional 

changes at the conclusion of the short pulse life testing, except for T/VA S/N 020 which 

experienced partial flow blockage. 

Table 4-2 presents the results of the T/VA gas (CN2) flow and the valve opening response 

testing. 

4.7 HARDWARE FAILURES 

4.7.1 

T/VA S/N 020 experience partial flow blockage after 13,000 pulses during life testing. 

This unit was disassembled and inspected. It was determined that the blockage was in the 

thruster injector capillary tube. The injector was sectioned and a material buildup was 

found at the downstream end of the capillary tube. 

T/VA S/N 020 Experimced Partial Flow Blockage 

Y 

An analysis of the material was performed at JPL and was determined to be composed of 

iron, nickel and chromium; the constituents of stainless steel. It was further determined 

that the metals were dissolved as carbazates or hydrazides in hydrazine used during 

previous testing. 

t 

The deposition occurred prior to the short pulse testing and the observed flow reduction 

was caused by a particle, probably a piece of the deposition, which broke free and lodged 

in smaller flow area of the deposition buildup. 

4.73 Thruster Heater Failures 

There were four thruster heater element failures but the heaters on the T/VA's used in 

this test program all had the small (1 mil) elements wire. The flight units have a different 

heater with a 2.5-mil element or they have a resistor in series with the element. 

XD/287 4-26 
i 

,,I 

! 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

*I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

1 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

I 

1 

. 

m 

I 

I 

(v 

a 

II 8 

t 

Figure 4-23 

VISd - 3WlSS3tld 2!38t.(VH3 

4-21 
y! 

n 

x 

b 

f 

E 

428 
5.0 CONCLUSIONS 

0 The limiting electrical pulse width is approximately 3.0 milliseconds. At pulse 

widths of 3.0 ms or less the valve will not unseat and no impulse will be obtained. 

0 Pulse widths of 3.5 milliseconds provide an impulse bit of approximately 20 percent 

of the impulse provided by a 10 millisecond pulse, but there is a wide variation in 

pulse-to-pulse and unit-to-unit impulse. 

0 Pulse widths of 4.0 milliseconds provide an impulse bit of approximately 45 percent 

of the impulse provided by a 10-millisecond pulse and the pulse-to-pulse and unit-tounit variation is approximately plus or minus 10 percent. 

0 Pulse widths of 5.0 milliseconds provide an impulse bit of approximately 55 percent 

of the impulse provided by 10-millisecond pulse and the pulse-to-pulse and unit-tounit variation is approximately pluse or minus 8 percent. 

0 Seventy-five thousand (75,000) short pulses of 4 milliseconds and shorter cause no 

performance degradation. Three units showed no effect. One unit exhibited partial 

-flow reduction after 13,000 pulses but this is attributed to the previous testing 

history. 

0 There is no significant risk associated with short pulse operation. This is supported 

by: 1) a successful demonstration test program was completed, 2) 410,000 pulses 

were accumulated on one T/VA during the Voyager qualification test, and 3) 75,000 

short pulses represents less than 1 percent of the qualified hydrazine throughput 

capability. 

0 The disassembly and sectioning of the injector on T/VA S/N 019 and/or 016 would 

support the contention that the flow blockage of T/VA S/N 020 is due to previous 

testing history if a low degree of deposition was discovered. 

0 The Voyager T/VA's should be considered flight qualified for short pulse operation at 

pulse widths of 4 milliseconds or greater. 1 

\ 

XD/287 5- 1 
I( 

I' 

I 

I 

I 

APPENDIX A 

HYDRAZINE ANALYSES 
. 

i 

f ( 

- 

c - 

-.-_ -- 

A- I 

.. 
he Rr-rvcd: Charge No.: I 2 s2 2- 3300 Control No.: (1 3 sc3 

Chock Up#r 

80. For All 

--- 

I I 

-I 

Conorkiry 0.00115 Y Fr mu. 12.5 Wm 

OJOrib 0.- mrx. S oom 

I- O.ooo1 mu. 2 PPm 

1 I I I I 

\ ( it Completed And Reviewtd: 

PCCEPTABLE VALUES 1 

HIGH 

- 

PURlfY 

GRAD€ 

I 

"I 

39. 

20.0 

1 mdL ma. N/A 

O.2 ppm 

Lr 
-- 

..vL~~ I nLaCnnCn cv~rA.7~~ 

HYDRAW-t3LALYlICAL FORM 

FOR HYDUUIhf MEETIFiG MIL -f - 26536, AMENDMENT 1 n 

1cJS min. 

0.020 mP(. 2m 3,r0.- mu. W Is OOm 

O.ml0 ma. 10 

O.al2S % Fe m. 12, 

0.oOQz ma. 2 0,I - 

A-3 
.. * 

ROCKET RESEARCH COMPANY 

HYDRAZINE ANALYTICAL FORM 

FOR HYDRAZINE MEETING MIL - P - 26536, AMENDMENT 2 

Date Recieved: &/* e3- Charge No.: /sfxm- Control No.: 6362 

L,iporition of Sample: oes+coy 

r 

:heck Upper 

Bor Fa All 

--- 

ACCEPTABLE VALUES 

MONOPROPELLANT 

REOUEST€D $RAD€ I I I I YBYWEIGHT ppm 

1-00 max. 

0.40 ma*. 

0.020 mar. . .rce Organics 

Eucluding Aniline 200 

Aniline I I 0.50mar. N!A :I 

c I I I 0.0020 mar. 20 Total Nonvolrtiler I V") 

Particulate 1 mg'L mar. 

Corrosivity 0.00125 %Fe mrx. 12.5 

c I I 

0.000005mu. 0.05 I Silicon 

(OPT ION AL I 

I I I 

'vris Completed And Reviewed: 

-7 RESULTS 

vvm 

I Chock Upper 

-Sox For All 

I I ---- 

ACCEPTABLE VALUES I I I . RESULTS HIGH PURITV 

GRADE I c 

YBYWEIGHT I pgm I 

~ 

b 0.8 3 1 .00 mar. N/A 

0.16 ' I 0.40 mar. N/A I 

29 vvm 

0.005 max. 50 

I 2P ppm I 0.005 mat. 

N !A 

0.0010 mrx 

1 mg'L mar. 

0.00125 k Fe mar. 12.5 1.1 ppm 

I 0.5 pvm I 0.0002 mar. 

0.0030 mar. 30 5 vvm 

0.0000(Wmar. 0.05 PVm 

Signature Date __-- 4-!7-.gs--- 

A4 

S36 A fII#) 
.dlllltcke@s - PaonQu~ L 

/ 

ROCKET RESEARCH COMPANY 

HYDRAZINE.ANALYTICAL FORM 

FOR HYDRAZiNE MEETING MIL - P - 26536, AMENDMENT 2 

B FaAll 7 RESULlS 

I Chock Upper -Box For All 

ACCEPTABLE VALUES 

---- 

ACCEPTABLE VALUES 

1 

I 

MONOQROQELLANT 

YBVWElGHf gQm 

EFIAOf 

HIGH PURITV I RESYLTS 

- GRADE 

YBYWEIGHT pgm I 

OB.50,min. N/A 

1 .00 ma*. NIA 

0.40 mar, NIA '2.40 mar. t 

0.020 mal . 100 

0.50 mal. NfA . Aniline 

! 

-- ~~ 

0.0030 mar,. 20 

1 mg'L mar. NfA 

0.0010 ma* 10 I I 3 P?m 

1 mdL ma*. N/A 0 me'L 

0.00125 \ Fe mar. 125 0.00125 % Fe Wk. 12.5 I*? . ppm 

I Chloride O.ooo5 mu. 

-- ~~ 

0.0002 muc. 3 

0.0030 mar. 30 

' 0.0000~mu. 0.06 I 

~ 

0.0002 mat. 2 0*5 PPm 

0.0030 mat. 30 9 Pvm 

0.WOOO5mu. 0.05 c pvm 

0 

YT 

Silicon 

I ON AL 1 -* 

I I 

/US CWnpltttd A-d Reviewed: 

\ 

Signature 4, ?ado Date -_- 7-26-85 -7- 

A-5 
ROCKET RESEARCH COMPANY 

HYORAZINE ANALYTICAL FORM 

FOR HYDRAZINE MEETING MIL - P - 26536, AMENDMENT 2 

0 z 

RESULTS 

--- 

1 ANALYSES 1 

REOUESTED 

-- 

ACCE?TABLE VALUES ACCEPTABLE VALUES 

MON OP ROPE LL ANT 

s!!!AE€ . RESULTS 

4 

YBYWElGHT ppn 

W.50 min. N/A 99.00 min N/A 

1.00 mu. N/A 

0.40 mra. NIA 

1.00 mu. N1 A 

0*/9 ’ 0.40 mu. N/A 

0.020 mra. 100 4006 mu. 50 

0.50 mrx . N/A Y 0.005 mJ* . 60 

0.00 10 mra 10 

1 mg‘L mrx. N/A 

- 

~~ 

0.0020 mar. 10 

1 m@’L mar. NIA 

0.00125 % Fe mu. 123 0.00125 Y Fe mm. 125 

Chloride 0.0WS max. 6 I O.Ooo5 mu. % 

I ’- 0.0002 mm. 2 0.7 ePm 0.0002 ma. 2 

L- 0.0030 m8X. 30 Sllicon 

wm 0.0030 mru. 30 

0.000005ma. 0.0 0.000006mu. 0.06 -ppm 

I 

us Completed And Reviewed: a