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Author: Gronich S. Riedesel R.G. Johnson K.P. Holl R.J.
Tags: military affairs nuclear weapons astronautics
Year: 1970
Text
SECOND INTERIM BRIEFING NUCLEAR SHUTTLE DEFINITION STUDY, PHASE III ^ PREPARED FOR NASA-MSFC UNDER CONTRACT NAS8-24714 DRL NO. MSFC-DRL-196, LINE ITEM NO. 2 IVICOONISI£LL DOUGLAS ASTKOIVAUTICS COIt/IPAIVV .y MICDONMELL MDC G0747 16 DECEMBER 1970 g»<fUGLAS} COPY NO. 39 DISTRIBUTION OF THIS DOr'WftfT iJuj^iMtYfio
DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.
%mB moumLMm SECOND INTERIM BRIEFING NUCLEAR SHUTTLE DEFINITION STUDY, PHASE III 16 DECEMBER 1970 PREPARED FOR NASA-MSFC UNDER CONTRACT NAS8-24714 DATA REOUIREMENTS LIST NO. MSFC-DRL-196, LINE ITEM NO. 2 5301 Bolsa Avenue, Huntington Beach, CA 9264 7 MDC G0747
14906 PHASE III SECOND INTERIM BRIEFING REUSABLE NUCLEAR STAGE CONCEPTS NUCLEAR SHUTTLE SYSTEM DEFINITION STUDY CONTRACT NAS 8-24714 16 DECEMBER 1970 1 - NOTICE- This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Energy Research and Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal iiability or responsibiiity for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. SliTiyBUnOM GF THIS >2uUUfALiii UiiLkwiiiLi
NUCLEAR SHUTTLE SYSTEM DEFINITION STUDY During P h a s e I and P h a s e II of the nuclear flight s y s t e m definition study, the cont r a c t e d effort (1) evaluated t h r e e c l a s s e s of r e u s a b l e nuclear shuttle concepts that could efficiently p e r f o r m m i s s i o n s from low e a r t h orbit to either lunar orbit or synchronous e a r t h orbitj and p e r f o r m planetary m i s s i o n s in the shuttle mode, (2) identified systemi element c h a r a c t e r i s t i c s that have major impact on the economics of the n u c l e a r shuttle o p e r a t i o n s , and (3) defined nuclear stage c h a r a c t e r i s t i c s . At the conclusion of this p h a s e , it was decided to p r o c e e d with a P h a s e A conceptual definition for two v a r i a t i o n s of the r e u s a b l e nuclear shuttle: (1) a 33-ft d i a m e t e r , l o a d - c a r r y i n g tank that could be launched to e a r t h orbit by the I n t e r m e d i a t e - 2 1 (Int-21) launch vehicle, and (2) propellant modules delivered to low e a r t h orbit within the c a r g o hold of the Space Shuttle, The objectives of this study a r e to define the r e u s a b l e nuclear stage concepts m o r e completely and e s t a b l i s h integrated t e s t , manufacturing, facility and equipment, and supporting r e s e a r c h and technology plans in o r d e r that a p r e l i m i n a r y technical plan, a development schedule, and p r o g r a m costs can be identified for each of these concepts. A c o m p a r i s o n between the two c l a s s e s of RNS vehicles will be made at the conclusion of this study. 2
NUCLEAR SHUTTLE SYSTEM DEFINITION STUDY ^^^ ® OVERALL OBJECTIVE ® ESTABLISH PHASE A CONCEPTUAL DEFINITION FOR TWO VERSIONS OF REUSABLE NUCLEAR SHUHLE ® 33 FT DIAMETER DERIVATIVE ® EOS COMPATIBLE ® SPECIFIC OBJECTIVES ® COMPLETE PRELIMINARY TECHNICAL DEFINITION OF THE RNS CONCEPTS ® ESTABLISH INTEGRATED PROGRAM REQUIREMENTS FOR THE SELECTED RNS CONCEPTS ® CONDUCT SPECIALIZED ANALYTICAL STUDIES ® PROVIDE MISSION AND PERFORMANCE ANALYSES DATA ® IDENTIFY PHYSICAL AND FUNCTIONAL INTERFACES WITH OTHER SYSTEM ELEMENTS 3
BRIEFING SCHEDULE The organization of the briefing and the s p e a k e r s a r e shown in the accompanying figure. 4
BRIEFING SCHEDULE EXECUTIVE SUMMARY S. GRONICH MISSION OPERATIONS R. G. RIEDESEL RNS DESIGN K. P. JOHNSON R. J. NOLL PROGRAM PLAN R. G. RIEDESEL
STUDY SCHEDULE The schedule identifies the t a s k s to be p e r f o r m e d under the nuclear shuttle study and indicates the c u r r e n t status of each of the individual efforts. The study is b r o k e n into t h r e e p h a s e s , which consist of about 3 - 1 / 2 months each: (1) concept definition and evaluation, (2) s y s t e m t r a d e s t u d i e s , and (3) p r o g r a m and s y s t e m definition. As indicated on the schedule, the t a s k s initiated during the first phase w e r e m i s s i o n capability a n a l y s i s , operations r e q u i r e m e n t s and s y s t e m s definition of specific s u b s y s t e m s in o r d e r to p e r f o r m p r e l i m i n a r y configuration definition, and e n g i n e - s t a g e interface definition. In addition, engineering t r a d e studies such as engine-stage vehicle dynamics and engineering support activities (Task 9) w e r e initiated during this phase of the study. T r a d e analyses for s t r u c t u r e s , propulsion, a u x i l i a r y propulsion and a s t r i o n i c s u b s y s t e m s w e r e conducted during the second portion of the P h a s e III study. These will be r e p o r t e d on at this briefing. In addition, m i s s i o n and RNS o p e r a tions w e r e further updated and i n t e g r a t e d - p r o g r a m - p l a n - r e l a t e d t a s k s w e r e initiated. 6
14866 STUDY SCHEDULE MONTHS FROM ATP STUDY TASK 2 1 TASK 1 - MISSION CAPABILITY ANALYSIS TASK 2 - OPERATIONS REQUIREMENTS 3 4 5 6 7 e 8 12 ^ ^ P B M I ^ ^ ^ ^ ^ ^ ^ ^ ^ M ^ ^ M i ^ ^ M i M ^ ^ ^ H TASK 4 - TEST REQUIREMENTS EBE TASK 5 - MANUFACTURING REQUIREMENTS TASK 6 - FACILITIES DEFINITION TASK 7 - SUPPORTING RESEARCH AND TECHNOLOGY PROGRAM ^ 1 1 »».-, — N 1 TASK 8 - PROGRAM DEFINITION ! 1 i. • N | TASK 11 - STUDY MANAGEMENT ORIENTATION WORKING REVIEWS 11 u • • • TASK 3 - SYSTEMS DEFINITION TASK 10 - STUDY DOCUMENTATION 10 1 i 1 ~T A i^ A A BRIEFINGS A LETTER PROGRESS REPORTS A • A BRIEFING BROCHURES A A A A A A A A ik A A FINAL REPORTS A OUTLINE DRAFT FINAL 1 7 1 ! ! ll___
CONCEPTS EVALUATED The C l a s s 1 and 3 RNS concepts a r e shown in the accompanying figure. At the conclusion of P h a s e 11, the C l a s s 1 hybrid, which consisted of a s m a l l propellant r u n tank and engine, delivered within the cargo hold of the space shuttle and a 33-ft d i a m e t e r propellant module delivered by the INT~21 launch vehicle, was adopted as a p r i m a r y b a s e l i n e . Specific design analyses of a standard configuration with a 10-degree conical aft dome would also be studied to a depth sufficient to define major technical p r o b l e m s . The aft angle for the C l a s s 1 Hybrid configuration will also be a simulated 10-degree angle in o r d e r to optimize the shield and tank configuration of the o v e r a l l s y s t e m . The propellant tank for the C l a s s 1 hybrid is fabricated from 2014-T6 aluminum alloy and i n t e g r a l l y stiffened cylind r i c a l section. The s m a l l propellant run tank is of a monocoque construction, and the total capacity of both tanks is about 300, 000 lb of p r o p e l l a n t . F i b e r - g l a s s heat blocks and high-performance insulation, which can be c o m p r e s s e d during launch, a r e used to t h e r m a l l y p r o t e c t the propellant t a n k s . A f i b e r - g l a s s bumper and foam a r e used for the b a s i c m e t e o r o i d protection s y s t e m . RNS equipment was placed in the forward s k i r t a r e a ; a modular configuration of the s u b s y s t e m s was devised to provide maintainability. At the conclusion of a t r a d e study conducted during the first t h r e e months of the c u r r e n t study effort, a single command and control module, which would be r e m o v e d after each m i s s i o n for r e p l e n i s h m e n t and r e p a i r , was selected over the previous design. The planar configuration of the C l a s s 3 s y s t e m was selected at the conclusion of P h a s e II on the b a s i s of a t r a d e analysis between shielding r e q u i r e m e n t s and vehicle stiffness. On further investigation in the first t h r e e months of P h a s e III, which evaluated the impact of a s s e m b l y o p e r a t i o n s , a c r u c i f o r m configuration was s e l e c t e d . At the s a m e t i m e , further definition of fluid line deployment, flexible e l e m e n t s , and docking and c l u s t e r i n g m e c h a n i s m s was m a d e . An i n t e g r a l n u m b e r of propellant modules was selected with a total capacity slightly g r e a t e r than 300, 000 lb. This r e p r e s e n t e d a configuration with eight m o d u l e s . The propellant modules would be of aluminum monocoque construction, and all of the other s u b s y s t e m s would be s i m i l a r to that d e s c r i b e d for the C l a s s 1 hybrid concept. The C l a s s 3 functional s u b s y s t e m s would be packaged in a command and control m o d u l e . Scheduled maintenance in this concept would be achieved by removing the e n t i r e command control m o d u l e . 8
18103 CONCEPTS EVALUATED „»»;**•• ^ ' 9
RNS STUDY PHASE IH TASKS The major outputs of the study p h a s e s indicated on the schedule a r e shown on the accompanying figure. Mission p e r f o r m a n c e and capability of the RNS would be further updated for the specific concepts defined p r e v i o u s l y for four m i s s i o n s : (1) a lunar o r b i t - t o - o r b i t shuttle, (2) a geosynchronous o r b i t - t o - o r b i t shuttle, (3) unmanned p l a n e t a r y p r o b e s , and (4) manned p l a n e t a r y m i s s i o n s . Specific p r e l i m i n a r y operational r e q u i r e m e n t s , functional a n a l y s e s , and a r e l i a b i l i t y i m p r o v e m e n t plan, which impact the concepts definition and t h e i r evaluation, would be generated during the first p h a s e . Subsystem a n a l y s e s and t r a d e studies w e r e also conducted in the p h a s e . During the second phase a l t e r n a t i v e RNS s y s t e m s and s u b s y s t e m designs would be updated to reflect the operational r e q u i r e m e n t s , reliability i m p r o v e m e n t s , t h e r m o d y n a m i c a n a l y s e s , new radiation e n v i r o n m e n t s , and N E R V A / R N S interface definition. The intent of the activity would be to p r e s e n t a l t e r n a t i v e RNS designs for final review at the end of 7 m o n t h s . During this phase of the study, t e s t , facility and GSE r e q u i r e m e n t s , and m a n u facturing techniques would be identified. In the last p h a s e , a final RNS s y s t e m d e s c r i p t i o n would be p r e p a r e d , including h a r d w a r e t r e e s , design d e t a i l s , and s y s t e m specifications. Complete functional a n a l y s e s , r e l i a b i l i t y allocation s h e e t s , safety contingency p l a n s , and interface r e q u i r e m e n t s would be identified. L a s t l y , the integrated p r o g r a m would be for mulated and an o v e r a l l p r o g r a m cost would be e s t a b l i s h e d . 10
RNS STUDY PHASE III TASKS CONCEPT DEFINITION AND EVALUATION ® MISSION PERFORMANCE AND TIMELINES ® RELIABILITY IMPROVEMENT PLAN ® OPERATIONS ANALYSIS ® SUBSYSTEM DESIGN REQUIREMENTS SYSTEM TRADE STUDIES ® SUBSYSTEM DESIGN ® UPDATE FLIGHT SYSTEM DEFINITION ® INITIATE PROGRAM PLANS PROGRAM AND SYSTEM DEFINITION ® FINALIZE REQUIREMENTS DEFINITION ® DOCUMENT BASELINE SYSTEM DEFINITIONS ® COMPLETE INTEGRATED PROGRAM PLANS ® PREPARE INTERFACE RECOMMENDATIONS 11
LUNAR SHUTTLE MISSION TIMELINE-EARTH ORBIT TURNAROUND The accompanying i l l u s t r a t i o n identifies m a j o r activities o c c u r r i n g bet'ween orbit i n s e r t i o n (EOI) following a lunar shuttle m i s s i o n and subsequent d e p a r t u r e on another m i s s i o n . The total time available for e a r t h orbit turnaround of 84. 2 days c o r r e s p o n d s to a m i s s i o n model with a s i x - m i s s i o n s - a - y e a r frequency. F o r this m i s s i o n model, two RNS s y s t e m s a l t e r n a t e l y p e r f o r m lunar shuttle m i s s i o n s at a combined rate of once each 54. 6 days (every two lunar cycles). Since the m i s s i o n s a r e p e r f o r m e d a l t e r n a t e l y by the two RNS's, 84. 2 days a r e spent in e a r t h orbit by each RNS between m i s s i o n applications. In o r d e r to m i n i m i z e , if not eliminate, the r e q u i r e m e n t to p e r f o r m recycling operations simultaneously on the two RNS's, only a portion of this time is allocated for the p e r f o r m a n c e of the m a j o r operations of propellant refueling and m i s s i o n payload launch and integration. A space shuttle launch rate of one each t h r e e days is r e q u i r e d to fulfill this objective. Specific a r e a s investigated included launch and prelaunch operations, lunar shuttle phasing cycles, utilization schedules, logistic t u r n around cycles, and p e r f o r m a n c e impact of after cooling and APS impulse r e q u i r e m e n t s . Time in the s u m m a r y p e r m i t s only a revievA on the next chart of the p e r f o r m a n c e impact of the t r a n s lunar after cooling. The figure indicates the combined launch of the new command and control module and m i s s i o n cre'w. This approach is taken to m a x i m i z e the use of the space shuttle payload capability. Should future i n v e s t i gations indicate this approach untenable because of the extended crew time r e q u i r e d in each orbit (an additional 14 days of on-orbit time), the crew could be launched s e p a r a t e l y , following launch and integration of the unmanned payload, at the expense of an added space shuttle launch. 12
18109 LUNAR-SHUTTLE MISSION TIMELINE EARTH ORBIT TURNAROUND - SIX MISSIONS PER YEAR V^ - 2 ^ 13 LH2 TRANSFER (10 LAUNCHES*) 27 DAYS POST-FLIGHT CHECKOUT AND CONTINGENCY FOR UNSCHEDULED MAINTENANCE (AS REQUIRED) 41 DAYS CONTINGENCY FOR UNSCHEDULED MAINTENANCE (AS REQUIRED) 4 DAYS LAUNCH CREW AND CCM EXCHANGE CCM'S SUBSYSTEM VERIFICATION INTEGRATED TEST 3 DAYS —~~¥—^ " LAUNCH AND INTEGRATE UNMANNED PAYLOAD (3 LAUNCHES*) 6 DAYS TOTAL TURNAROUND TIME IN EARTH ORBIT = 84.2 DAYS DEPLOY EARTHRETURN PAYLOAD 4HR INTEGRATED TEST FRT AND COUNTDOWN 1 DAY COOLDOWN OPERATIONS 45 HR EOI Ws = 47,530 LB TUG INTERCEPT AND CREW RETRIEVAL --6HR h 72-HR COAST *3 DAYS BETWEEN SHUTTLE LAUNCHES 13 w. TLI 174.820 LB T 108-HR COAST
P E R F O R M A N C E I M P A C T - T R A N S L U N A R COOLDOWN U T I L I Z A T I O N E s t i m a t e s m a d e to d a t e of t h e b a s e l i n e RNS p e r f o r m a n c e for t h e l u n a r s h u t t l e m i s s i o n h a v e not c r e d i t e d i m p u l s e d e r i v e d d u r i n g t h e N E R V A c o o l d o w n p h a s e t o w a r d t h e a c c o m p l i s h m e n t of m i s s i o n v e l o c i t y m a n e u v e r s . T h u s , in effect, p r o p e l l a n t c o n s u m e d f o r t h e N E R V A c o o l d o w n function w a s t r e a t e d a s a n o n p r o p u l s i v e , u n u s a b l e p r o p e l l a n t . T h e p e r f o r m a n c e i m p l i c a t i o n s of t h i s a s s u m i p t i o n h a v e b e e n e v a l u a t e d u s i n g a t w o - b o d y p a t c h e d c o n i c s o l u t i o n for t h e b a s e l i n e 1 0 8 - h o u r t r a n s l u n a r m i s s i o n l e g . T h e r e f e r e n c e c o n d i t i o n ( z e r o c o o l d o w n u s e d for i m p u l s e ) w a s a p a y l o a d d e l i v e r y c a p a b i l i t y to l u n a r o r b i t of 112,000 lb (20, 000 lb c r e w m o d u l e on the r e t u r n l e g ) , b a s e d on a N E R V A s t e a d y - s t a t e r u n t i m e of 1, 800 s e c o n d s . T h e c o o l d o w n i m p u l s e p r o f i l e w a s m o d e l e d p e r A e r o j e t R e p o r t S-1 3 0 - B P - 0 9 0 2 9 0 - F L P R E L , " N E R V A R e f e r e n c e Data—Full F l o w E n g i n e , " d a t e d A p r i l 1970. T h e d u r a tion of the c o o l d o w n p h a s e in t h i s c a s e is a c t u a l l y s o m e w h a t in e x c e s s of t h e 1 0 8 - h r t r a n s f e r t i m e b e t w e e n t h e e a r t h and t h e m o o n . T h e t o t a l i m p u l s e c o n t r i b u t e d d u r i n g t h e c o o l d o w n p h a s e f o r t h i s p a r t i c u l a r e n g i n e r u n t i m e w o u l d be 3. 3 X 1 0 " l b - s e c , o r an e q u i v a l e n t c h a r a c t e r i s t i c v e l o c i t y of 320 f t / s e c . T o t a l u s e of t h e cooldo'wn i m p u l s e for t h e t r a n s l u n a r v e l o c i t y r e q u i r e m e n t r e s u l t s in a n e q u i v a l e n t r e d u c t i o n in t h e f u l l - t h r u s t v e l o c i t y r e q u i r e m e n t of a p p r o x i m a t e l y 130 f t / s e c , r e s u l t i n g in a p e r f o r m a n c e i m p r o v e m e n t of a p p r o x i m a t e l y 3, 400 l b . T h i s 3, 4 0 0 - l b p e r f o r m a n c e i m p r o v e m e n t w o u l d be i n c r e a s e d f u r t h e r by an a d d i t i o n a l 1 1 , 0 0 0 l b p e r f o r m a n c e g a i n if the r e q u i r e m e n t f o r e n g i n e c o o l d o w n could be c o m p l e t e l y elimiinated. T h a t i s , t h e 7, 600 lb of p r o p e l l a n t p r e s e n t l y a l l o c a t e d for c o o l d o w n c o u l d b e r e a s s i g n e d for u s e d u r i n g f u l l - t h r u s t o p e r a t i o n s . T h i s p o t e n t i a l p e r f o r m a n c e i m p r o v e m e n t ( 1 1 , 000 lb) w o u l d h a v e to be p l a y e d a g a i n s t a n y s y s t e m w e i g h t i n c r e a s e s r e q u i r e d to effect cooldown e l i m i n a t i o n (for e x a m p l e r a d i a t o r s y s t e m s ) . T h e p e r f o r m a n c e imipact of i n c r e a s e s in RNS s y s t e m i n e r t w e i g h t is 2. 7 lb l o s t in o r b i t a l p a y l o a d p e r p o u n d i n c r e a s e in i n e r t w e i g h t , o r a p p r o x i m a t e l y a 4, 000 lb i n e r t w e i g h t i n c r e a s e a s t h e b r e a k - e v e n p o i n t . 14
PERFORIVIANCE IfVIPACT OF NERVA AFTERCOOLING IfViPULSE UTILIZATION 18078 i S 8 ^ S INCREASE IN PAYLOAD DELIVERED TO LUNAR ORBIT (LB) TRANSLUNAR WIISSfON PHASE d / / 0 20 40 60 80 PERCENT OF COOLDOWN IMPULSE UTILIZED 15 100
RNS DESIGN The context for the c u r r e n t phase of the RNS design activity is given on the facing chart. P h a s e II r e s u l t e d in definition of the two basic RNS concepts—the singlemodule, 3 3 - f t - d i a m e t e r C l a s s 1 concept and the multiple-module C l a s s 3 configuration. The first period of P h a s e 3 focused on selection of m a j o r c h a r a c t e r i s t i c s for each concept and the o v e r a l l configuration of the v e h i c l e s . The m o s t significant selection during this period was that of a d i s c r e t e command and control module for the C l a s s 1 concept to m o s t effectively a c c o m p l i s h orbital m a i n t e n a n c e . Another m a j o r r e s u l t of the first period analysis was the selection of the C l a s s 3 vehicle configuration with the modules in the form of a c r u c i f o r m c l u s t e r . Operations w e r e analyzed in support of making the above concept/ configuration selections as well as to provide the b a s e s for m o r e detailed definition of the RNS itself. During the second period m a j o r design activities -were oriented tow^ard t r a d e studies selecting specific s u b s y s t e m design f e a t u r e s . To accomiplish t h e s e t r a d e studies, detailed operations analysis, using the s c e n a r i o s developed during the first period, w e r e p e r f o r m e d to establish s u b s y s t e m r e q u i r e m e n t s . Subsequent c h a r t s will show the operations analysis and s u b s y s t e m definition for the RNS functional s u b s y s t e m s . This section will conclude with a s u m m a r y of the inajor features selected during this period and with the c u r r e n t weight statement for both RNS concepts which a r e s u m m a r i z e d on the next t'wo c h a r t s . 16
RNS DESIGN ® FIRST PERIOD RESULTS: «RNS CONCEPT/CONFIGURATION • CLASS 1 - - CCM FOR MAINTENANCE « CLASS 3 - - CRUCIFORM CLUSTER ® OPERATIONS « MISSION TIMELINE ® ORB ITAL ASSEMBLY AND REFURB I SHMENT « RNS OPERATIONS ® SECOND PERIOD OBJECTIVES: ® DESIGN FEATURE TRADE STUDIES ® DETAIL OPERATIONS TO ESTABLISH REQUIREMENTS 17
R N S C L A S S 1 HYBRID A s k e t c h of the C l a s s 1 H y b r i d RNS c o n f i g u r a t i o n i s s h o w n on t h e f a c i n g c h a r t . It i l l u s t r a t e s t h e c u r r e n t c o n f i g u r a t i o n and p r o v i d e s a l o c a t o r for t h e s p e c i f i c f e a t u r e s s e l e c t e d d u r i n g t h e s e c o n d p e r i o d of t h e s t u d y w h i c h w i l l be d i s c u s s e d on subsequent c h a r t s . The t h r e e d i s t i n c t m o d u l e s a r e v i s i b l e a s w e l l a s t h e i r c o n t a i n m i e n t w i t h i n t h e 1 0 d e g r e e half-angle cone m e a s u r e d from the NERVA engine which was selected d u r i n g t h e P h a s e II s h i e l d o p t i m i z a t i o n . T h e o u t r i g g e r s c o n t a i n i n g t h e a u x i l i a r y p r o p u l s i o n e n g i n e s on t h e c o m m a n d and c o n t r o l m o d u l e s a r e a l s o v i s i b l e on t h e p i c t u r e . S p e c i f i c d e t a i l s a r e i d e n t i f i e d by t h e c a l l o u t s . 18
CLASS 1 HYBRID RNS COMAAAND & CONTROL MODULE FORWARD UMBILICALSLOSH BAFFLE INTEGRAL WAFFLE TUNNEL INTER-MODULE STRUCTURE DOCKING INTERFACE LIQUID LEVEL SENSORS APS NOZZLESPRAY NOZZLE REFILL PROPELLANT MODULE PROPELLANT FEED SYSTEM PROPULSION MODULE NERVA 19 -THERMAL/METEOROID PROTECTION
RNS CLASS 3 This c h a r t shows the c u r r e n t baseline configuration for the Class 3 RNS concept. Clustering of outboard propellant modules into a c r u c i f o r m configuration at the second propellant module level is i l l u s t r a t e d . Comparison with the previous sketch shows how both RNS concepts have converged in t h e i r c h a r a c t e r i s t i c s by definition of the functional m o d u l e s . It can be seen that the only basic difference between the two concepts is the m a n n e r in which propellant is stored—within the multiple miodules in this c a s e and in the single propellant module for the C l a s s 1 Hyb rid. The main feed s y s t e m , providing communication from any propellant module to the run tank on the propulsion module, is shown in this figure. Other details a r e noted by the callouts. Again, this sketch should be used as a locator for the discussion of the design features selected during this period. 20
CLASS 3 RNS COMMAND & CONTROL MODULE THERMAL/METEOROID PROTECTION INTER-MODULE STRUCTURE PROPELLANT FEED SYSTEM DOCKING INTERFACE LIQUID LEVEL SENSORS PROPELLANT MODULES INBOARD TRANSFER NERVA PROPULSION MODULE 21
DESIGN FEATURES SELECTED This and the next c h a r t s u m m a r i z e some of the major design f e a t u r e s which w e r e selected during the second study period. It should be kept in mind that many major design features w e r e selected in both the P h a s e 11 study and during the f i r s t period of P h a s e III. The forward dome shape for the C l a s s 1 propellant module was r e - e v a l u a t e d in t e r m s of the c u r r e n t hybrid launch mode and m i s s i o n utilization. It was found that approximately a 600-lb reduction in operational weight could be achieved with only a 19-in. i n c r e a s e in the length of the module. An integral waffle p a t t e r n was provided for all C l a s s 3 propellant modules to withstand launch loads. This stiffening also allows t r a n s m i s s i o n of RNS operational modes through the inboard modules to the payload without p r e s s u r e in the propellant miodule t a n k s . Optimization of the run tank d i a m e t e r for the C l a s s 3 propulsion module yielded a l 6 0 - i n . value. This included consideration of shielding optiinization, s t r u c t u r a l a n a l y s i s , and o p e r a t i o n s . No biological shielding is r e q u i r e d with this configuration. The fiber glass composite s t r u c t u r e which was selected during P h a s e II for the t h r u s t s t r u c t u r e s and intermodule s t r u c t u r e s was reviewed during this period. Utilizing c u r r e n t values for insulation p e r f o r m a n c e and s t r u c t u r a l weight sensitivity to stage p r e s s u r e r e i n f o r c e s the selection of fiber glass which was made during P h a s e II. As d e s c r i b e d e a r l i e r in the p r e s e n t a t i o n , an autonomous navigation systemi was selected with the provision of utilizing ground tracking for backup. It w a s also shown that data p r o c e s s i n g r e q u i r e m e n t s a r e c o n s i s t e n t with the c e n t r a l i z e d computer and that this approach could make m o s t effective u s e of equipment for r e d u n d a n c i e s . Also as shown e a r l i e r s t o r e d p r o c e d u r e s a r e utilized for checkout with BITE employed for specific components. 22
18115 DESIGN FEATURES SELECTED ® HEMISPHERICAL FORWARD DOME-CLASS 1 PROPELLANT MODULE ® INTEGRAL WAFFLE PAWERN-CLASS 3 PROPELLANT MODULE ® 160 INCH RUN TANK DIAMETER-CLASS 3 PROPULSION MODULE ® FIBERGLASS COMPOSITE STRUCTURE-REVIEWED ® AUTONOMOUS NAVIGATION ® CENTRALIZED DATA PROCESSING ® STORED PROCEDURES FOR ONBOARD CHECKOUT ® BITE FOR SPECIFIC COMPONENTS 23
DESIGN FEATURES SELECTED ~ 2 Additional c h a r a c t e r i s t i c s for RNS s u b s y s t e m s which w e r e selected during the second period a r e shown on the facing c h a r t . The integrated chilldown s u b s y s t e m which combines the NERVA and stage chilldown operations as well as including the operations a s s o c i a t e d with refill or the run tank following depletion was d e s c r i b e d e a r l i e r . Additionally, a blocking valve was added in the C l a s s 3 feed s y s t e m s connecting the v a r i o u s propellant module tanks into the run tank. This enhances feed systemi integrity as well as eliminating e x c e s s i v e liquid r e s i d u a l s following shutdown and e x c e s s i v e t h e r m a l l e a k s . The auxiliary propulsion s y s t e m was sized for both concepts. A engine t h r u s t -was selected based upon performing requisite m a n e u v e r s , attitude control, and propellant settling. Total propellant capacity was e s t a b l i s h e d for the baseline lunar shuttle m i s s i o n . The p r i m a r y power s o u r c e t r a d e study p e r f o r m e d during P h a s e II was reviewed in t e r m s of c u r r e n t power r e q u i r e m e n t s . The final selection was made between fuel cells and s o l a r cells utilizing s t a t e - o f - t h e - a r t projections for fuel cells which a r e being employed in the space shuttle, and for s o l a r cells which a r e to be employed in advanced space p r o g r a m s beyond Skylab, The evaluation favored fuel cells for the RNS. Redundant fuel cells a r e provided for r e l i a b i l i t y . 24
DESIGN FEATURES SELECTED - 2 # INTEGRATED CHILLDOWN SUBSYSTEM ® COMBINED NERVA/STAGE CHILLDOWN ® INCLUDES REFILL OF RUN TANK # BLOCKING VALVE IN FEED SUBSYSTEM-CLASS 3 # AUXILIARY PROPULSION SYSTEM SIZED ® ENGINE THRUST ® PROPELLANT CAPACITY # REDUNDANT FUEL CELLS-PRIMARY POWER-REVIEWED
RNS WEIGHT STATEMENT The accompanying c h a r t contains c u r r e n t weight s t a t e m e n t s for both RNS concepts. F o r n e a r l y identical propellant capacities it can be seen that both the s t r u c t u r e , m e t e r o i d / t h e r m a l , and docking/clustering e n t r i e s penalize the multiple-module C l a s s 3 concept. The main propulsion e n t r y contains a 2 , 8 0 0 - l b biological shield for the C l a s s 1 Hybrid concept which a l m o s t offsets the g r e a t e r plumbing and component weights for the C l a s s 3 concept. The l a s t t h r e e e n t r i e s under the dry weight a r e n e a r l y the same for both concepts, A net d r y weight advantage of n e a r l y 10, 000 lb a c c r u e s to the C l a s s 1 concept. It can be seen that the RCS propellant is n e a r l y identical for both concepts, but that the r e s i d u a l s of propellant contained in the stage at burnout a r e about 75, 000 lb h e a v i e r for the C l a s s 1 concept than for C l a s s 3, This r e s u l t s in a net difference in operational weight of only about 2, 000 lb favoring C l a s s 1. These g r e a t e r r e s i d u a l s for the C l a s s 1 concept diminish the usable propellant so that the propellant m a s s fraction, \ ' , given as the l a s t e n t r y is identical for both configurations. 26
18117 RNS WEIGHT STATEMENT CLASS 1 HYBRID CLASS 3 (LB) (LB) STRUCTURE METEOROIDA'HERMAL DOCKING/CLUSTER NG MAIN PROPULSION AUX LIARY PROPULSION ASTRIONICS CONTINGENCY 24,080 7,910 760 31,220 1,010 2,135 1,840 28,750 8,800 3,440 31,840 1,010 2,430 2,410 TOTAL DRY WEIGHT 68,955 78,680 1,130 9,470 1,140 1,920 79,555 81,740 1,700 289,830 2,240 1,700 297,190 0.784 0.784 RCS PROPELLANT PROPELLANT RESIDUALS TOTAL OPERATIONAL WEIGHT VENTED PROPELLANT FLIGHT PERFORMANCE RESERVE USABLE PROPELLANT PROPELLANT MASS FRACTION, A'
L A U N C H AND P R E L A U N C H O P E R A T I O N S - C L A S S 1 H Y B R I D O p e r a t i o n s i n v o l v i n g t h e l a u n c h of t h e RNS w i l l b e s c h e d u l e d to m e e t t h e r e q u i r e m e n t s of t h e S p a c e S h u t t l e . A l s o , t h e c o n f i g u r a t i o n d e m a n d s m a d e on t h e s h u t t l e w i l l b e h e l d to a m i n i m u m . T h e s e c o n s i d e r a t i o n s give r i s e to t h e e s t a b l i s h m e n t , a s a b a s e l i n e , of t h e r e c e i p t of t h e RNS e l e m e n t s in l a u n c h r e a d y c o n d i t i o n . T h e r e f o r e , the o p e r a t i o n a l p r o f i l e s p r e s e n t e d on t h i s and t h e n e x t f i g u r e s a r e b a s e d on t h e s e a s s u m p t i o n s . T h e r e a r e s e v e r a l additional, m o r e detailed, a s s u m p t i o n s that have shaped the baseline profile p r e s e n t e d . M a t i n g w i t h t h e s p a c e s h u t t l e w i l l b e in t h e h o r i z o n t a l p o s i t i o n in t h e s h u t t l e m a i n t e n a n c e a r e a . T h e o r b i t e r c a r g o c o m p a r t m e n t w i l l be a c c e s s i b l e to a c r e w m e m b e r in o r b i t . In o p e r a t i o n s t h a t i n v o l v e t h e I N T - 2 1 (i. e, , C l a s s 1 h y b r i d o p e r a t i o n s ) i t i s a s s u m e d t h a t M T F w i l l be o p e r a t i o n a l and w i l l h a v e t h e c a p a b i l i t i e s n e e d e d to p e r f o r m a c c e p t a n c e t e s t i n g on b o t h t h e p r o p e l l a n t m o d u l e and the propulsion m o d u l e . The a c c o m p a n y i n g figure shows the C l a s s 1 b a s e l i n e o p e r a t i o n a l profile. The a s s u m p t i o n that the m o d u l e w i l l be l a u n c h - r e a d y w h e n it i s r e c e i v e d i s r e f l e c t e d in t h e u s e of t h e l o w b a y a i s l e a s t h e r e c e i v i n g i n s p e c t i o n a r e a . O p e r a t i o n s h e r e w i l l be l i m i t e d to r e m o v i n g s h i p p i n g p r o t e c t i o n and v e r i f y ing t h a t t h e o r b i t e r / p r o p u l s i o n - m o d u l e a n d t h e I N T - 2 1 / p r o p e l l a n t - m o d u l e i n t e r f a c e s a r e r e a d y f o r m a t i n g . If r e c e i v i n g o p e r a t i o n s s h o u l d r e q u i r e s i g n i f i c a n t l y l o n g e r t i m e , t h e n r e c e i v i n g o p e r a t i o n s on t h e p r o p e l l a n t m o d u l e w o u l d be m o v e d to one of t h e VAB h i g h b a y s if i n t e g r a t e d p r o g r a m c o n s i d e r a t i o n s permit. T h e p r o p e l l a n t m o d u l e a n d t h e c o m m a n d a n d c o n t r o l m o d u l e w i l l be l a u n c h e d i n t e g r a l l y . T h e y w i l l b e m a t e d at M i c h o u d a n d m o v e d to M T F for p r o d u c t i o n a c c e p t a n c e t e s t i n g . T h e n t h e y w i l l be s h i p p e d to KSC for l a u n c h v e h i c l e I n t e g r a t i o n , C / O , and l a u n c h . In C l a s s 1 h y b r i d o p e r a t i o n s ( a s w e l l a s C l a s s 3) t h e s c h e d u l e of t h e p r o p u l s i o n m o d u l e w i l l be p l a n n e d to m e e t t h e r e q u i r e m e n t s of t h e S p a c e S h u t t l e . F o r s a f e t y , the n e u t r o n s o u r c e f o r N E R V A , if r e q u i r e d , w i l l not b e i n s t a l l e d until o r b i t i s r e a c h e d , a n d the p o i s o n w i r e s w i l l r e m a i n in t h e c o r e u n t i l o r b i t . Both of t h e o p e r a t i o n s w i l l r e q u i r e a c r e w m e m b e r to e n t e r t h e c a r g o c o m p a r t m e n t of t h e o r b i t e r in o r b i t ; and t h a t h e h a v e t h e n e c e s s a r y a c c e s s to a c c o m p l i s h t h i s t a s k . T h e p r o p u l s i o n m o d u l e w i l l h a v e i t s n u c l e a r and n o n n u c l e a r s u b s y s t e m s s h i p p e d to NRDS, m a t e d a n d t e s t e d t h e r e . T h e y w i l l be flown to t h e C a p e w h e r e t h e y w i l l b e m a t e d w i t h t h e p r o p u l s i o n m o d u l e t a n k a g e . O n e of t h e low b a y c e l l s w i l l b e u s e d f o r t h i s o p e r a t i o n . T h e e n g i n e w i l l h a v e b e e n fully s a f e d by p o i s o n w i r e s a n d no s p e c i a l n u c l e a r s a f e t y p r e c a u t i o n s w i l l b e r e q u i r e d e x c e p t f o r c o n t r o l l e d a c c e s s and p e r i o d i c m o n i t o r i n g of t h e a r e a a n d p e r s o n n e l . A d d i t i o n a l l y , t h e e n g i n e w i l l not h a v e , a t t h i s t i m e , t h e n e u t r o n s o u r c e i n s t a l l e d . T h i s s o u r c e w i l l be i n s t a l l e d by a m e m b e r of t h e o r b i t e r c r e w a f t e r o r b i t h a s b e e n a c h i e v e d a n d p r i o r to h i s r e m o v i n g t h e p o i s o n w i r e s . 28
18068 PRELAUNCH AND LAUNCH OPERATIONS CLASS 1 HYBRID RNS POST-MANUFACTURING C/O PRODUCTION ACCEPTANCE TESTING INT-21 MISSION OPERATIONS PROPELLANT LOADING, C/O AND COUNTDOWN (MICHOUD/SB) COMMAND & CONTROL MODULE (HB) (AIR) PROPELLANT MODULE MTF (AIR) CCM/PM (BARGE) — • RECEIVING INSPECTION (AISLE) I PAD ORBIT n CCM/PROPELLANT MODULE MISSION VEHICLE ASSEMBLY AND C/O KSC VAB LOW BAY (BARGE) (MICHOUD) PROPULSION MODULE TANKAGE VAB HIGH NERVA/ TANKAGE (A!R) (HB) BAY MATING NUCLEAR SUBSYSTEM (WAND I BOOSTER ORBITER NRDS NON-NUCLEAR SUBSYSTEM (AGO NERVA SYS PROPULSION MODULE LOADING (HORIZONTAL POSITION) NERVA ASSEMBLY AND TEST SPACE SHUTTLE MAINTENANCE AREA ORBITER T BOOSTER ¥ a»ACE SHUTTLE SAFING AREA 29 SPACE SHUTTLE LANDING SITE
L A U N C H A N D P R E L A U N C H OPERATIONS-CLASS 3 O p e r a t i o n s for t h e C l a s s 3 RNS i n t e r f a c e only w i t h the s p a c e s h u t t l e . C o n s e q u e n t l y t h e c o m m a n d and c o n t r o l m o d u l e vi^ill be l a u n c h e d s e p a r a t e l y f r o m the other naodules. The p r i m e d i f f e r e n c e b e t w e e n C l a s s 3 o p e r a t i o n s and C l a s s 1 h y b r i d o p e r a t i o n s is in t h e u s e of S a c r a m e n t o a s a s i t e f o r p r o d u c t i o n a c c e p t a n c e t e s t i n g . T h i s diff e r e n c e r e s u l t s f r o m t h e a s s u m p t i o n t h a t t h e I N T - 2 1 i s not o p e r a t i o n a l and t h e r e f o r e M T F w i l l h a v e b e e n c l o s e d down. A n o t h e r p o s s i b i l i t y is t h a t t h e s p a c e s h u t t l e p r o g r a m w i l l fully u t i l i z e M T F so t h a t i t i s u n a v a i l a b l e f o r t h e RNS p r o g r a m . T h e p r o p e l l a n t m o d u l e s w i l l b e i n s p e c t e d in the VAB low b a y a r e a . T h i s r e c e i v i n g i n s p e c t i o n w i l l b e l i m i t e d to v e r i f i c a t i o n t h a t t h e m o d u l e s h a v e n o t b e e n d a m a g e d in s h i p m e n t , and v e r i f i c a t i o n t h a t t h e s p a c e - s h u t t l e - o r b i t e r / p r o p e l l a n t - m o d u l e i n t e r faces a r e r e a d y for m a t e . T h e p r o p u l s i o n m o d u l e w i l l b e h a n d l e d s i m i l a r l y to t h e o p e r a t i o n s u s e d f o r t h e Class 1 hybrid configuration. This includes mating the propulsion inodule tankage a n d t h e N E R V A s y s t e m in t h e low b a y c e l l s of t h e V A B . 30
18069 PRELAUNCH AND LAUNCH OPERATIONS CLASS 3 RNS POST-MANUFACTURING C/O COMMAND % PROPELLANT LOADING C/O AND COUNTDOWN CONTROL MODULE PRODUCTION ACCEPTANCE TESTING (HB) PROPELLANT MODULES MISSION VEHICLE ASSEMBLY & C/O LAUNCH VEHICLE INTEGRATION (BARGE) (HB) PROPULSION MODULE TANKAGE (HB) RECEIVING INSPECTION NUCLEAR SUBSYSTEM (WAND — —% NRDS .^::^>^JL^—= (AIR) A 1MERVA \SSEMBLY AND T l^SIE^ MODULE LOADING (HORIZONTAL .POSITION) VAB LOW BAY NERVA/TANKAGE MATING -NON-NUCLEAR SUBSYSTEM (AGO ^ MISSION OPERATIONS SPACE SHUTTLE MAINTENANCE AREA ORBITER I SPACE SHUTTLE SAFING AREA BOOSTER 31 »ACE SHUTTLE LANDING SITE
L U N A R S H U T T L E MISSION T I M E L I N E - E A R T H O R B I T T U R N A R O U N D The accompanying illustration identifies m a j o r activities o c c u r r i n g between o r b i t i n s e r t i o n (EOI) following a l u n a r s h u t t l e m i s s i o n and s u b s e q u e n t d e p a r t u r e on a n o t h e r m i s s i o n . T h e t o t a l t i m e a v a i l a b l e f o r e a r t h o r b i t t u r n a r o u n d of 8 4 . 2 d a y s c o r r e s p o n d s to a m i s s i o n m o d e l w i t h a s i x - m i s s i o n s - a - y e a r f r e q u e n c y . F o r t h i s m i s s i o n m o d e l , two RNS s y s t e m s a l t e r n a t e l y p e r f o r m l u n a r s h u t t l e m i s s i o n s at a c o m b i n e d r a t e of o n c e e a c h 54. 6 d a y s ( e v e r y two l u n a r c y c l e s ) . S i n c e the m i s s i o n s a r e p e r f o r m e d a l t e r n a t e l y by the two R N S , 84. 2 d a y s a r e s p e n t in e a r t h o r b i t by e a c h RNS b e t w e e n m i s s i o n a p p l i c a t i o n s . In o r d e r to m i n i m i z e , if not e l i m i n a t e , t h e r e q u i r e m e n t to p e r f o r m r e c y c l i n g o p e r a t i o n s s i m u l t a n e o u s l y on the two RNS, only a p o r t i o n of t h i s t i m e i s a l l o c a t e d f o r the p e r f o r m a n c e of the m a j o r o p e r a t i o n s of p r o p e l l a n t r e f u e l i n g and m i s s i o n p a y l o a d l a u n c h and i n t e g r a t i o n . A s p a c e s h u t t l e l a u n c h r a t e of one e a c h t h r e e d a y s i s r e q u i r e d to fulfill t h i s o b j e c t i v e . Two t i m e b l o c k s a r e a l l o c a t e d m t h e p r o f i l e shown to p e r f o r m u n s c h e d u l e d m a i n t e n a n c e . T h e f i r s t b l o c k of t i m e (41 d a y s ) i m m e d i a t e l y follows the c o m p l e t i o n of c o o l d o w n o p e r a t i o n s and m i s s i o n c r e w r e t r i e v a l . T h i s t i m e b l o c k p r o v i d e s f o r m a j o r m a i n t e n a n c e such as propellant module r e p l a c e m e n t . A s i m i l a r , but s m a l l e r , b l o c k of t i m e i s a l l o c a t e d following e x c h a n g e of the RNS c o m m a n d and c o n t r o l m o d u l e and s u b s y s t e m v e r i f i c a t i o n and i n t e g r a t e d t e s t s . T h e e x t e n t to w h i c h t h e f i r s t u n s c h e d u l e d m a i n t e n a n c e p e r i o d (41 d a y s ) i s u s e d c o r r e s p o n d i n g l y i n f r i n g e s upon t h e p e r f o r m a n c e of t u r n a r o u n d o p e r a t i o n s on t h e a l t e r n a t e RNS, and w o u l d i m p o s e a g r e a t e r b u r d e n b e c a u s e of i n c r e a s e d s p a c e s h u t t l e l a u n c h f r e q u e n c y a n d o r b i t a l a c t i v i t y . T h e f i g u r e i n d i c a t e s t h e c o m b i n e d l a u n c h of the new c o m m a n d a n d c o n t r o l m o d u l e and m i s s i o n c r e w . T h i s a p p r o a c h i s t a k e n to m a x i m i z e t h e u s e of t h e s p a c e s h u t t l e p a y l o a d c a p a b i l i t y . Should f u t u r e i n v e s t i g a t i o n s i n d i c a t e t h i s a p p r o a c h u n t e n a b l e b e c a u s e of t h e e x t e n d e d c r e w t i r a e r e q u i r e d m e a r t h o r b i t (an a d d i t i o n a l 14 d a y s of o n - o r b i t t i m e ) , t h e c r e w could be l a u n c h e d s e p a r a t e l y , following l a u n c h and i n t e g r a t i o n of t h e u n m a n n e d p a y l o a d , at the e x p e n s e of an a d d e d s p a c e s h u t t l e l a u n c h . 32
18109 LUNAR-SHUTTLE MISSION TIMEUNE EARTH ORBIT TURNAROUND - SIX MISSIONS PER YEAR K^ r , ^ o LH2 TRANSFER (10 LAUNCHES*) 27 DAYS POST-FLIGHT CHECKOUT AND CONTINGENCY FOR UNSCHEDULED MAINTENANCE (AS REQUIRED) 41 DAYS CONTINGENCY FOR UNSCHEDULED MAINTENANCE (AS REQUIRED) 4 DAYS LAUNCH CREW AND CCM EXCHANGE CCM'S SUBSYSTEM VERIFICATION INTEGRATED TEST 3 DAYS LAUNCH AND INTEGRATE UNMANNED PAYLOAD (3 LAUNCHES*) 6 DAYS TOTAL TURNAROUND TIME IN EARTH ORBIT = 84.2 DAYS DEPLOY EARTHRETURN PAYLOAD 4HR INTEGRATED TEST FRT AND COUNTDOWN 1 DAY COOLDOWN OPERATIONS 45 HR EOI Wp = 47,530 LB TUG INTERCEPT AND CREW RETRIEVAL ^ 6HR h 72-HR COAST *3 DAYS BETWEEN SHUTTLE LAUNCHES 33 w. TLI = 174,820 LB T 108-HR COAST
COPLANAR LUNAR SHUTTLE PHASING T h e s p a c i n g of l u n a r s h u t t l e m i s s i o n o p p o r t u n i t i e s i s s h o w n in t h i s c h a r t . It i s b a s e d on a t a r g e t p o l a r l u n a r o r b i t of 60 n m i , and a d e p a r t u r e f r o m a 2 6 0 - n m i , 3 1 . 5 - d e g r e e ~ i n c l i n a t i o n , e a r t h - o p e r a t i o n s o r b i t . D u r i n g a y e a r , 13 m i s s i o n o p p o r t u n i t i e s e x i s t , c o n s i s t i n g of s e v e n l o n g - s t a y l u n a r m i s s i o n s and s i x s h o r t stay lunar m i s s i o n s . The opportunities repeat every 54.6 days. The lower p o r t i o n of t h e c h a r t d e t a i l s t h e t i m e l i n e a s s o c i a t e d w i t h e a c h o p p o r t u n i t y . For t h e l o n g e r s t a y m i s s i o n , 1 7 . 6 d a y s a r e a l l o w e d in l u n a r o r b i t , w h i l e 4. 0 d a y s a r e a l l o w e d for t h e s h o r t e r s t a y m i s s i o n . F o r e i t h e r m i s s i o n t h e o u t b o u n d t r i p t i m e i s 4. 5 d a y s a n d the r e t u r n l e g i s 3. 0 d a y s . 34
18070 COPLANAR LUNAR SHUTTLE PHASING LUNAR ORBIT 54.6 DAYS EARTH ORBIT 4 0 DAYS LUNAR ORBIT / \ ^ 3 . 0 DAYS 4.5 DAYS / / 0 40.1 51.6 DAYS 35 EARTH ORBIT
RNS U T I L I Z A T I O N S C H E D U L E T y p i c a l RNS o p e r a t i n g p l a n s w e r e g e n e r a t e d for t r a f f i c m o d e l s of two and f o u r m i s s i o n s a y e a r . T h e s c h e d u l e at t h e t o p of t h e c h a r t i s for two m i s s i o n s a y e a r u s i n g o n e RNS. T h i s low t r a f f i c r a t e a l l o w s a m i n i m u m of 138. 8 d a y s in e a r t h o r b i t f o r p e r f o r m i n g t h e t u r n a r o u n d o p e r a t i o n s and any c o n t i n g e n c y m a i n t e n a n c e . T h e s c h e d u l e a t t h e l o w e r p o r t i o n of t h e c h a r t r e f l e c t s a t r a f f i c m o d e l of f o u r m i s s i o n s a y e a r and u s e s two RNS s y s t e m s . RNS No. 1 p e r f o r m s s h o r t l u n a r - s t a y m i s s i o n s w h i l e RNS N o . Z p e r f o r m s long l u n a r - s t a y m i s s i o n s . T h e m i n i m u m t i m e b e t w e e n s u c c e s s i v e m i s s i o n s w i t h t h e s a m e RNS i s 84. 2 d a y s f o r RNS No. Z. H o w e v e r , not a l l of t h i s t i m e i s a v a i l a b l e to p e r f o r m t h e t u r n a r o u n d o p e r a t i o n s . A g r o u n d r u l e w a s f o r m u l a t e d r e s t r i c t i n g t u r n a r o u n d o p e r a t i o n s to one RNS at a t i m e . A s a r e s u l t of t h i s n o n i n t e r f e r e n c e p h i l o s o p h y , only 69 d a y s a r e a v a i l a b l e to r e s u p p l y RNS N o . 2 a f t e r r e t u r n i n g f r o m i t s f i r s t m i s s i o n . T h e i m p l i c a t i o n s of p e r f o r m i n g t u r n a r o u n d o p e r a t i o n s on two RNS s y s t e m s c o n c u r r e n t l y a r e a d d i t i o n a l r e q u i r e m e n t s for o r b i t a l s u p p o r t s y s t e m s , s u c h a s s p a c e t u g s . 36
18105 RNS UTILIZATION SCHEDULE ON MISSION INEARTH ORBIT 138,8 DAYS ZAAISSIONS/YEAR^ONERNS n LI 1^1 C •152.3 DAYS RNS NO. 1 TURNAROUND OPERATIONS 3 138.8 DAYS RNS N0« 2 4 MISSIONS/YEAR-TWO RNS L 0 40 80 120 160 200 TIME (DAYS) 37 240 280 320 360
RNS U T I L I Z A T I O N S C H E D U L E - T W O RNS S Y S T E M S T h i s c h a r t p r e s e n t s t y p i c a l RNS o p e r a t i n g p l a n s f o r six and e i g h t m i s s i o n s a y e a r w h e n u s i n g two RNS s y s t e m s . F o r t h e s i x m i s s i o n s p e r y e a r , 84. 2 d a y s a r e s p e n t in e a r t h o r b i t b e t w e e n s u c c e s s i v e m i s s i o n s w i t h t h e s a m e RNS. H o w e v e r , it c a n b e s e e n t h a t both RNS s y s t e m s a r e in e a r t h o r b i t at t h e s a m e t i m e d u r i n g c e r t a i n p o r t i o n s of t h e s c h e d u l e . To a v o i d o p e r a t i o n a l i n t e r f e r e n c e , a g r o u n d r u l e w a s e s t a b l i s h e d l i m i t i n g l o g i s t i c s s u p p o r t o p e r a t i o n s to one RNS at a t i m e . A s a r e s u l t , only a p o r t i o n of t h e t i m e in e a r t h o r b i t w i l l be a v a i l a b l e f o r r e s u p p l y o p e r a t i o n s ; t y p i c a l l y t h i s w o u l d be 54. 6 d a y s p r i o r to l e a v i n g on a m i s s i o n . T h e l o w e r s c h e d u l e r e f l e c t s an e i g h t - m i s s i o n - a - y e a r t r a f f i c m o d e l u s i n g two RNS s y s t e m s . T h e t i m e b e t w e e n s u c c e s s i v e u s e of t h e s a m e RNS v a r i e s w i t h t h e m i n i m u m b e i n g 57. 7 d a y s . U s i n g t h e s a m e n o n i n t e r f e r e n c e - o p e r a t i o n s p h i l o s o p h y d i s c u s s e d a b o v e r e s u l t s in a m i n i m u m a l l o t t e d r e s u p p l y t i m e of 42. 1 days. 38
18071 RNS UTILIZATION SCHEDULE TWO RNS •ON MISSION r 84.2 DAYS EARTH ORBIT 84.2 DAYS RNS NO. 1 TURNAROUND OPERATIONS 84.2 DAYS 84.2 DAYS RNS NO. 2 6 MISSIONS/YEAR 69.6 DAYS !5 5 RNS r T r T i i i 97.7 DA NO. 1 I i i i I , I 8 i i i 57.7 DAYS RNS NO. 2 8 MISSIONS/YEAR 0 40 80 120 160 200 TIME (DAYS) 39 240 280 320 360
O R B I T G E O M E T R Y DURING COOLDOWN T h e o r b i t a l g e o m e t r y r e s u l t i n g f r o m t h e cooldown i m p u l s e p r o f i l e following full p o w e r e n g i n e o p e r a t i o n i s shown f o r a c a s e r e p r e s e n t a t i v e of t h e E O I m a n e u v e r . T h e p u l s e i s s p e c i f i e d by i t s m i d - p o i n t a s e a c h p u l s e w a s t r e a t e d a s an i m p u l s i v e p e r t u r b a t i o n to t h e o r b i t . T h e c o o l d o w n p h a s e i s a s s u m e d to be a c c o m p l i s h e d at z e r o a n g l e - o f a t t a c k t h r o u g h o u t , t h a t i s , t h e t h r u s t v e c t o r is a l w a y s a l i g n e d w i t h t h e v e l o c i t y v e c t o r . Two o b s e r v a t i o n s t h a t r e l a t e to t h e c h a r a c t e r i s t i c e a r l y a c c u m u l a t i o n of t h e m a j o r i t y of t h e c o o l d o w n i m p u l s e a r e (1) t h a t t h e d e s i r e d i n j e c t i o n o r b i t , (the o r b i t d e s i r e d at t h e end of f u l l - p o w e r o p e r a t i o n ) is e c c e n t r i c , and (Z) t h e o r b i t b e c o m e s n e a r - c i r c u l a r v e r y quickly. T h e d a t a show t h a t if i n s e r t i o n o c c u r s in an i n i t i a l o r b i t of 437 n m i a p o g e e by 366 n m i p e r i g e e (the e c c e n t r i c i t y is 0 . 0 0 9 3 ) , t h e RNS w i l l r e t r o down to a 2 6 0 - n m i c i r c u l a r o r b i t by t h e end of t h e c o o l d o w n p h a s e . S p e c i f i c a l l y , t h e end of f u l l - t h r u s t s h u t d o w n o c c u r s a t an a l t i t u d e of 381 m i l e s at an i n i t i a l flight p a t h a n g l e of - 0 . 4 4 d e g r e e s . The n e g a t i v e flight p a t h a n g l e , a n d the c l o s e n e s s of t h e i n j e c t i o n a l t i t u d e to the p e r i g e e a l t i t u d e n o t e d , i n d i c a t e t h a t i n j e c t i o n o c c u r s p r i o r to p e r i g e e p a s s a g e . T h e t o t a l c o o l d o w n p h a s e , in t h i s c a s e , l a s t s for 52. 8 h o u r s following s h u t d o w n , o r a t o t a l of 33. 5 o r b i t a l r e v o l u t i o n s . When c o n s i d e r i n g t h e a c c u m u l a t e d i m p u l s e d e r i v e d f r o m c o o l d o w n d u r i n g t h i s r e t r o g r a d e p h a s e , a c o r r e s p o n d e n c e i s shown to t h e r e d u c t i o n in a v e r a g e o r b i t a l a l t i t u d e (the s u m of a p o g e e a l t i t u d e p l u s p e r i g e e a l t i t u d e d i v i d e d by 2), a s w o u l d b e e x p e c t e d . F o r e x a m p l e , f o u r o r b i t s following i n j e c t i o n ( 2 3 , 000 s e c o n d s ) , 80 p e r c e n t of t h e c o o l d o w n i m p u l s e to b e d e r i v e d h a s b e e n d e l i v e r e d and, c o r r e s p o n d i n g l y , 80 p e r c e n t of the a v e r a g e a l t i t u d e r e d u c t i o n h a s b e e n a c c o m p l i s h e d . S i m i l a r l y , 90 p e r c e n t of t h e e f f e c t i v e r e d u c t i o n in a v e r a g e a l t i t u d e i s a c c o n n p l i s h e d in l e s s t h a n n i n e o r b i t s , o r 14 h o u r s , following i n j e c t i o n . T h e t o t a l i d e a l v e l o c i t y c o n t r i b u t i o n d u r i n g t h i s c o o l d o w n p h a s e is a p p r o x i m a t e l y 470 f t / s e c , d e l i v e r e d at an e f f e c t i v e s p e c i f i c i m p u l s e of 441 s e c o n d s . 40
18072 1200 240O ORBIT GEOMETRY DURING COOLDOWN ^700 EARTH ORBIT INSERTION 300O 41
ORBITAL INSERTION PROFILE OPTIONS Noting that approximately 53 hours (or 33-1/2 orbital revolutions) a r e r e q u i r e d to complete the cooldown phase for the EOI m a n e u v e r , the question is r a i s e d as to the possibility of c r e w deployment p r i o r to the t e r m i n a t i o n of the cooldown phase. Tw^o a p p r o a c h e s to accomplishing this w e r e investigated: (1) injecting the RNS at a lo'wer initial orbit to p e r m i t spiraling down to 260 m i l e s m o r e quickly, followed by deploying the cre"w and allowing the RNS to complete the cooldown phase on its own, and (2) intercepting the RNS e a r l y in the cooldown phase at a higher orbit with another stage, such as the chemical tug, and r e t u r n i n g the c r e w to 260 nmi. In the l a t t e r c a s e , the RNS would continue its downward s p i r a l to 260 m i l e s following deployment of the c r e w . In the f o r m e r of the two a l t e r n a t e s , if 260 nmi i n s e r t i o n w e r e d e s i r e d at the end of tw^o orbital revolutions (following 40 cooldown pulses), injection m u s t occur in an orbit with a 394~nmi apogee and a 320-nmi p e r i g e e . This c o m p a r e s with the 437 by 365 nmi initial injection orbit, which would use all of the cooldown p r i o r to c i r c u l a r i z a t i o n at 260 nmi, as was previously d i s c u s s e d . Adopting this approach in effect r e s u l t s in depriving the RNS of the useful impulse o c c u r r i n g following c i r c u l a r i z a t i o n at 260 nmi. The effect is to i n c r e a s e the full - t h r u s t injection velocity r e q u i r e d by virtue of injecting into a lower e a r t h orbit. The payload impact of this higher energy r e q u i r e m e n t in this example is 950 lb. This payload penalty is c o m p a r e d with an equivalent cost for the second of the two a l t e r n a t i v e s mentioned, where a tug is a s s u m e d to i n t e r c e p t the RNS during its downward s p i r a l in the cooldown p h a s e . These data a r e based on the r e t r i e v a l of a 20, 000-lb c r e w module with a tug weighing 12, 000 lb (inert weight, as specified in the NASA Guidelines) at a specific impulse of 460 seconds. Thus, the profile entails t r a n s fer of the tug from the 260-nmi orbit up to the i n t e r c e p t orbit, acquisition of the c r e w module, followed by r e t u r n to the 260-nmi orbit. No velocity penalties -were assigned beyond the ideal Hohmann t r a n s f e r r e q u i r e m e n t . The tug propellant r e q u i r e m e n t to a c c o m p l i s h this sequence of events (10. 2 lb per nautical mile between 260 nmi and the i n t e r c e p t orbit) was converted to equivalent payload delivered to lunar orbit at the r a t e of 112, 000-lb of payload per 300, 000 lbs of propellant, or 0. 373 lb per lb. As can be seen, the second of the two a l t e r n a t i v e s is s u p e r i o r . 42
ORBITAL INSERTION PROFILE OPTIONS TOTAL UTILIZATION OF COOLDOWN IMPULSE EARLY CREW DEPLOYMENT EARLY CIRCULARIZATION 1 OPTION TIME TO CREW DEPLOYMENT (HR) PAYLOAD LOSS (LB) 2 TUG INTERCEPT 3 52.8 3.2 3,2 0 950 200 RNS+ CREW RNS ONLY 43
C O M M A N D AND CONTROL M O D U L E TURNAROUND CYCLE The c u r r e n t RNS operating plan calls for the r e t u r n of the command and control module (CCM) to the ground for maintenance and refurbishment subsequent to the completion of e v e r y RNS m i s s i o n . The objectives a r e : A. Replenish CCM c o n s u m a b l e s . B. Verify CCM functionality. C. Verify CCM r e d u n d a n c i e s . D. Calibrate and adjust components. E. Replace limited-life h a r d w a r e . The CCM turnaround cycle is i l l u s t r a t e d in the c h a r t . T r a n s p o r t a t i o n to and from orbit is by the space shuttle, which provides a protective environment during boost and entry. The ground maintenance could be p e r f o r m e d at KSC or at the manufacturing s i t e . The l a t t e r was selected as the m o s t cost-effective. The total turnaround time takes about 28, 5 days, of which 14 days a r e spent at the manufacturing site and ten days at KSC for prelaunch and launch o p e r a t i o n s . The turnaround cycle of 28. 5 days p r e s e n t s no h a r d s h i p on performing the candidate RNS traffic models of two to eight m i s s i o n s per y e a r . 44
18075 COMI^AND AND CONTROL MODULE TURNAROUND CYCLE ^^s^ " ^ Uf^LOAD CCM FBOM ORBITER 0.B HRS > PTT-I TRANSPORT TO RNS 0.e HRS ^sure •71.1 CONNECT/ DISCONNECT CCM 2.0 HRS Hm TRANSPORT CCM TO ORBITER 0.5 HRS BOOST CCM TO EARTH ORBIT 1.eT0 23HRS T ^ LOAD CCM IN ORBITER 0.5 HRS OEORBIT 4SMIN i SPACE SHUTTLE/ COM LAUiyCH OPS (VAB/PAD) 5 DAYS i LAND AT KSC LOAD CCIV! liy ORBITER 14MIN 3 DAYS I PERFORM CCM PRELAUNCH OPS 2 DAYS RELOAD CCM m GUPPY SHIP TO KSC 1 DAY ^ ^ : PERFORM MAINTENANCE 14 DAYS LOAD CCM IN GUPPY SHfPTOMFG 1DAY a ^ ( ^ ^ * ^ TOTAL TIME REQUIRED = 28.5 DAYS 45 OESERVICE CCM AT KSC 1 DAY
COMMAND AND CONTROL MODULE MAINTENANCE REQUIREMENTS To establish the t e r r e s t r i a l maintenance r e q u i r e m e n t s of the CCM, End Item Maintenance Sheets w e r e p r e p a r e d as i l l u s t r a t e d in the c h a r t . The CCM was broken down to the major a s s e m b l y l e v e l s , e. g. , s t a r t r a c k e r a s s e m b l y . The installation s t a t u s , maintenance function r e q u i r e d , maintenance frequency and maintenance location v/ere established for each of these major a s s e m b l i e s . Brief t a s k d e s c r i p t i o n s w e r e then generated for each of the identified maintenance functions defining what is to be done. These t a s k d e s c r i p t i o n s w e r e used by the maintenance support engineering staff and RNS study p e r s o n n e l for e s t i m a t e s of the t a s k - h o u r s and p e r s o n n e l r e q u i r e d . 46
18076 COIVIIVIAND AND CONTROL MODULE MAINTENANCE REQUIREMENTS ASTRIONICS S/S GUIDANCE, NAVIGATION & CONTROL STAR TRACKER ASSY *AEM ~ AFTER EVERY MISSION 47
COMMAND AND CONTROL MODULE MAINTENANCE SUMMARY TIMELINE This c h a r t p r e s e n t s a s u m m a r y CCM maintenance timeline. It is the r e s u l t of summations of m a n - h o u r s r e q u i r e d for individual maintenance functions performed on each major CCM a s s e m b l y . A major consideration in establishing the m a n hours r e q u i r e d for maintenance is that a high degree of automation would be used in checkout. An additional p r e r e q u i s i t e is that inaintainability be designed into the CCM. The unscheduled maintenance r e q u i r e m e n t is based on a i r c r a f t h i s t o r i c a l data necessitating 1 to 1.5 m a n - h o u r s of unscheduled maintenance for e v e r y hour of scheduled m a i n t e n a n c e . Major candidates for unscheduled maintenance a r e e l e m e n t s of the data m a n a g e m e n t s u b s y s t e m s , e. g. , the computer, a u x i l i a r y m e m o r y unit, e t c . 48
18077 COMMAND AND CONTROL MODULE MAINTENANCE SUMMARY TIMELINE lAPSED TIME (DAYS) TASKS 1 2 3 4 5 6 7 8 9 10 11 12 REMOVE ACCESS DOORS 41 • 42 FUNCTIONAL CHECKS UNSCHEDULED MAINTENANCE REPLACE ACCESS DOORS MANHOURS 8 VISUAL INSPECTION ITEM REPLACEMENT 13 14 174 B 305 8 SYSTEMS TEST 48 SERVICING 65 QUALITY ASSURANCE 224 915
SPACE SHUTTLE REQUIREMENTS FOR RNS TURNAROUND The figure identifies the nunaber of space shuttle vehicles r e q u i r e d for m i s s i o n accomiplishment as influenced by the annual m i s s i o n r a t e and shuttle turnaround t i m e . The turnaround t i m e s reflect the total time from launch to launch, including contingencies, for a given v e h i c l e . In establishing the space shuttle r e q u i r e m e n t s , the following ground r u l e s w e r e enforced: A. B. C. D. RNS RNS The Two r e q u i r e s 300, 000 lb of LH2. lunar payload is 112, 000 lb, a s s u m i n g a 20, 000-lb r e t u r n payload. COM weighs 6, 290 lb. candidate space shuttles w e r e c o n s i d e r e d : 1. E. 25K S/S—33, 000 lb delivered into a 260-nmi by 3 1 . 5 - d e g r e e e a r t h o r b i t . F o r propellant d e l i v e r y a 30, 000-lb capability was a s s u m e d , allowing 3, 000 lb for s t r u c t u r e (the o r b i t e r configured as an integral t a n k e r ) . 2, 40K S/S—50, 000 lb delivered into a 260-nmi by 3 1 . 5-degree e a r t h o r b i t . F o r propellant d e l i v e r y , a 40, 000-lb capability was a s s u m e d (the o r b i t e r configured as an integral tanker and volume limited). No propellant or payload storage facility in e a r t h or lunar o r b i t s . The r e q u i r e d launch r a t e s , which established the number of vehicles r e q u i r e d , a r e based on 14 and 11 space shuttle launches r e q u i r e d for turnaround for the 33, 000 and 50, 000-lb-capability v e h i c l e s , r e s p e c t i v e l y . The breakdown of this requirem.ent is as follows: Space Shuttle Capability to 260 n m i (i = 3 1 . 5 d e g r e e s ) 33, 000 lb 50, 000 lb LH2 Refueling 10 8 Payload (112,000 lb) and CCM __4_ __3_ 14 11 A single RNS is assigned to accomiplishing the t w o - m i s s i o n s - a - y e a r c a s e , while two RNS a r e assigned for the higher r a t e s , in all c a s e s , the u n i n t e r r u p t e d available t i m e between m i s s i o n s is used to complete turnaround a c t i v i t i e s , which a r e scheduled in such a m a n n e r as to not i n t e r f e r e with turnaround of the other RNS. Except for the e i g h t - m i s s i o n s - a - y e a r annual r a t e , the t u r n a r o u n d sequence is scheduled for c o m p l e tion as close as p o s s i b l e to the t r a n s l u n a r injection opportunity to m i n i m i z e the hold t i m e in a ready condition. This was not convenient in the e i g h t - m i s s i o n s - a - y e a r c a s e , and r e s u l t e d in the RNS being turned around i m m e d i a t e l y following r e t u r n from the m i s s i o n in some c a s e s to p r e v e n t i n t e r f e r e n c e with t u r n a r o u n d of the a l t e r n a t e RNS. C u r r e n t space shuttle definition studies a r e based on an eventual total p r o g r a m c a p a bility of 75 flights a y e a r with a turnaround capability of 14 days for each space s h u t t l e . 50
18108 SPACE SHUTTLE REQUIREMENTS FOR RNS TURNAROUND SPACE SHUTTLE TURNAROUND TIMES RNSM SSIONS/YEAR NUMBER OF 25/33K SPACE 15 DAYS 10 DAYS 5 DAYS 2 4 6 8 2 4 6 8 2 4 6 8 2 4 5 8 13 4 5 12 2 3 4 5 12 3 4 1 1 2 2 3 SHUTTLES REQUIRED NUMBER OF 4050K SPACE SHUTTLES REQUIRED 51 2
SPACE TUG UTILIZATION The figure identifies the r e q u i r e d availability and number of tugs r e q u i r e d to p e r f o r m requisite RNS o p e r a t i o n s . The extent of tug utilization is indicated by the number of operations per cycle as well as an a s s o c i a t e d e s t i m a t e of hours of active operation per cycle. Operations a r e defined as an activity r e l a t e d to the handling of an individual module, whether it be payload or RNS, F o r example, ten o p e r a tions a r e r e q u i r e d per cycle in module deployment during RNS assenn.bly to handle eight propellant m o d u l e s , one command and control module, and one propulsion module. The requiremient for four operations for payload deployment and a s s e m b l y is p r e d i c a t e d on a 33, 000-lb capability space shuttle to the 260-nmi, 31. 5 degree inclination operational orbit (25, 000 lb to 55 degree inclination). Two tugs a r e r e q u i r e d to p e r f o r m module a s s e m b l y , as well as command and control module r e p l a c e m e n t , as the stabilization function is provided the RNS by the command and control module. 52
18074 SPACE TUG UTILIZATION NO, OPERATIONS HOURS CYCLES* HOURS REQUIRED PER CYCLE PER CYCLE PER YEAR PER YEAR FUNCTIONS ASSEMBLY # MODULE DEPLOYMENT 1 10 10 <1 <10 # MODULE ASSEMBLY 2 12 <1 <12 m PAYLOAD DEPLOYMENT & ASSEMBLY 1 10 4*4f 8 <1 < 8 EARTH ORBIT TURNAROUND # COMMAND & CONTROL MODULE REPLACEMENT 2 1 4 6 24 # CREW MODULE RETRIEVAL 1 1 8 6 48 1 ^*^ 8 6 48 1 I 1L5 6 69 • # PAYLOAD DEPLOYMENT & ASSEMBLY LUNAR ORBIT OPERATIONS # PAYLOAD DEPLOYMENTS ASSEMBLY *BASED ON 6 RNS MISSIONS PER YEAR & A 3-YEAR OR lO-MISSION RNS DESIGN LIFE **25/33K LB CAPABILITY SPACE SHUTTLE
P E R F O R M A N C E I M P A C T - T R A N S L U N A R COOLDOWN U T I L I Z A T I O N E s t i m a t e s m a d e to d a t e of the b a s e l i n e RNS p e r f o r m a n c e for t h e l u n a r s h u t t l e m i s s i o n h a v e not c r e d i t e d i m p u l s e d e r i v e d d u r i n g t h e N E R V A c o o l d o w n p h a s e t o w a r d the a c c o m p l i s h m e n t of m i s s i o n v e l o c i t y m a n e u v e r s . T h u s , in effect, p r o p e l l a n t c o n s u m e d for t h e N E R V A cooldown function w a s t r e a t e d a s a n o n p r o p u l s i v e , u n u s a b l e p r o p e l l a n t . T h e p e r f o r m a n c e i m p l i c a t i o n s of t h i s a s s u m p t i o n h a v e b e e n e v a l u a t e d u s i n g a t w o - b o d y p a t c h e d c o n i c s o l u t i o n for t h e b a s e l i n e 1 0 8 - h o u r t r a n s l u n a r m i s s i o n l e g . T h e r e f e r e n c e c o n d i t i o n ( z e r o c o o l d o w n u s e d for i m p u l s e ) w a s a p a y l o a d d e l i v e r y c a p a b i l i t y to l u n a r o r b i t of 112,000 lb (20, 000 l b c r e w m o d u l e on t h e r e t u r n l e g ) , b a s e d on a N E R V A s t e a d y - s t a t e r u n t i m e of 1, 800 s e c o n d s . T h e cooldown i m p u l s e profile was m o d e l e d p e r A e r o j e t R e p o r t S - 1 3 0 - B P - 0 9 0 2 9 0 - F L P R E L , " N E R V A R e f e r e n c e D a t a - F u l l F l o w E n g i n e , " d a t e d A p r i l 1970. T h e d u r a tion of the cooldown p h a s e in t h i s c a s e i s a c t u a l l y s o m e w h a t in e x c e s s of t h e 1 0 8 - h r t r a n s f e r tiixie b e t w e e n t h e e a r t h a n d t h e m o o n . T h e t o t a l i m p u l s e c o n t r i b u ted d u r i n g t h e c o o l d o w n p h a s e f o r t h i s p a r t i c u l a r e n g i n e r u n t i m e w o u l d be 3. 3 X 1 0 " l b - s e c , o r an e q u i v a l e n t c h a r a c t e r i s t i c v e l o c i t y of 320 f t / s e c . T o t a l u s e of t h e c o o l d o w n i m p u l s e for t h e t r a n s l u n a r v e l o c i t y r e q u i r e m e n t r e s u l t s in a n e q u i v a l e n t r e d u c t i o n in t h e f u l l - t h r u s t v e l o c i t y r e q u i r e m e n t of a p p r o x i m a t e l y 130 f t / s e c , r e s u l t i n g in a p e r f o r m a n c e i m p r o v e m e n t of a p p r o x i m a t e l y 3, 400 l b . T h i s 3, 4 0 0 - l b p e r f o r m a n c e i m p r o v e m e n t w o u l d be i n c r e a s e d f u r t h e r b y an a d d i t i o n a l 1 1 , 0 0 0 l b p e r f o r m a n c e gain if the r e q u i r e m e n t for e n g i n e c o o l d o w n could be c o m p l e t e l y e l i m i n a t e d . T h a t i s , t h e 7, 600 lb of p r o p e l l a n t p r e s e n t l y a l l o c a t e d for c o o l d o w n c o u l d b e r e a s s i g n e d for u s e d u r i n g f u l l - t h r u s t o p e r a t i o n s . T h i s p o t e n t i a l p e r f o r m a n c e i m p r o v e m e n t ( 1 1 , 000 lb) w o u l d h a v e to be p l a y e d a g a i n s t any s y s t e m w e i g h t i n c r e a s e s r e q u i r e d to effect cooldown e l i m i n a t i o n (for e x a m p l e r a d i a t o r s y s t e m s ) . T h e p e r f o r m a n c e i m p a c t of i n c r e a s e s in RNS s y s t e m i n e r t w e i g h t is 2. 7 lb l o s t in o r b i t a l p a y l o a d p e r p o u n d i n c r e a s e in i n e r t w e i g h t , o r a p p r o x i m a t e l y a 4, 000 lb i n e r t w e i g h t i n c r e a s e a s t h e b r e a k - e v e n p o i n t . 54
PERFORMANCE IMPACT OF NERVA AFTERCOOLING IMPULSE UTILIZATION 18078 TRANSLUNAR MISSION PHASE CO 1 4000 HQQ Q^ O D^ < 3000 ZD ! o hQ LU Q^ LU > 2000 UJ Q Q < o! >< a. 1000 ^ LU CO < UJ Qe: o 0 20 40 60 80 PERCENT OF COOLDOWN IMPULSE UTILIZED 55 100
APS IMPULSE REQUIREMENTS Impulse and t h r u s t level r e q u i r e m e n t s for the APS have been established. These r e q u i r e m e n t s a r e displayed graphically h e r e . The total impulse for the C l a s s 1 hybrid configuration of approximately 453, 000 l b - s e c t r a n s l a t e s into 1, 132 lb of propellant, and the C l a s s 3 configuration r e q u i r e s 1, 138 lb of propellant to provide the 455, 0 0 0 - l b - s e c impulse r e q u i r e m e n t (Ig = 400 sec). A t h r u s t - l e v e l r e q u i r e ment of 100 lb has been selected to provide reasonable maneuver r a t e capability for attitude m a n e u v e r s . Axial t h r u s t - l e v e l r e q u i r e m e n t s of 3 lb (positive) and 200 lb (negative) for preignition separation and rendezvous m a n e u v e r s have been identified. T h e r e a r e seven distinct functions p e r f o r m e d by the APS during the lunar m i s s i o n . These a r e (1) attitude control during coast p h a s e s , (2) attitude m a n e u v e r s , (3) attitude control during cooldown thrusting, (4) s e p a r a t i o n m a n e u v e r s p r i o r to main stage ignition, (5) roll control during main engine b u r n s , (6) supplemental t h r u s t during rendezvous m a n e u v e r s , and (7) a c c e l e r a t i o n for propellant settling. Limit cycle r e q u i r e m e n t s a r e shown to be one to two o r d e r s of magnitude below other functional r e q u i r e m e n t s . Limit cycling was a s s u m e d to be accomplished within a plus or minus o n e - d e g r e e deadband, using a m i n i m u m impulse bit of 3 l b - s e c . Attitude m a n e u v e r s w e r e performed at a r a t e of 0. 1 d e g / s e c and include vehicle orientation for v a r i o u s NERVA o p e r a t i o n s , coast, separation, and gravity gradient storage in e a r t h and lunar o r b i t s . C o n t r a r y to engine operation at full t h r u s t and in the idle mode, where vehicle attitude is provided by gimbaling the NERVA to counteract overturning m o m e n t s , the APS is r e q u i r e d to stabilize the vehicle during cooldown o p e r a t i o n s . The r e q u i r e m e n t s shown for this function a r e based on an a s s u m e d 0. 1 degree m i s a l i g n m e n t between the cooldown t h r u s t vector and the vehicle c e n t e r of gravity. A velocity provision of 2, 5 f t / s e c each for separation from m a n n e d - l u n a r and e a r t h - o r b i t facilities p r i o r to NERVA operations was budgeted. Roll control r e q u i r e m e n t s evolve during the s t a r t t r a n s i e n t and s t e a d y - s t a t e engine o p e r a t i o n s . Steady-state impulse r e q u i r e m e n t s w e r e scaled at the r a t e of 500 l b - s e c plus 0. 1 l b - s e c per second of s t e a d y - s t a t e operation, based on experience with the J - 2 engine (scaled a p p r o p r i a t e l y ) . A velocity allocation for rendezvous m a n e u v e r s of 10 ft/.sec each for lunar orbit and e a r t h orbit rendezvous was m a d e . 56
18079 APS IMPULSE REQUIREMENTS CLASS 1 HYBRID CLASS 3 1,000.000 r SUBTOTAL 15% CONTINGENCY TOTAL CLASS 1 394. 300 CLASS 3 395., 700 59, 300 455, 000 (LB-SEC) 58, 700 453,000 100.000 o LU m I , ! UJ 10,000 - oo a. 1,000 L LIMIT ATTITUDE ATTITUDE SEPARATION ROLL MANEUVERS CONTROL DURING MANEUVERS CONTROL DURING COOLDOWN MAIN THRUSTING ENGINE BURN RENDEZVOUS MANEUVERS PROPELLANT SETTLING CYCLE 100 L- <1% 36% 10% 7% 13% 57 3% 28% 31% 10%
RNS DESIGN T h e c o n t e x t for t h e c u r r e n t p h a s e of t h e RNS d e s i g n a c t i v i t y is g i v e n on t h e f a c i n g c h a r t . P h a s e II r e s u l t e d in d e f i n i t i o n of t h e two b a s i c RNS concepts—the s i n g l e m o d u l e , 3 3 - f t - d i a m e t e r C l a s s 1 c o n c e p t and t h e m u l t i p l e - m o d u l e C l a s s 3 c o n f i g u r a t i o n . T h e f i r s t p e r i o d of P h a s e 3 f o c u s e d on s e l e c t i o n of m a j o r c h a r a c t e r i s t i c s f o r e a c h c o n c e p t and t h e o v e r a l l c o n f i g u r a t i o n of t h e v e h i c l e s . T h e m o s t s i g n i f i c a n t s e l e c t i o n d u r i n g t h i s p e r i o d w a s t h a t of a d i s c r e t e c o m m a n d and c o n t r o l m o d u l e f o r t h e C l a s s 1 c o n c e p t to m o s t e f f e c t i v e l y a c c o m p l i s h o r b i t a l m a i n t e n a n c e . A n o t h e r m a j o r r e s u l t of t h e f i r s t p e r i o d a n a l y s i s w a s t h e s e l e c t i o n of t h e C l a s s 3 v e h i c l e c o n f i g u r a t i o n w i t h t h e m o d u l e s in t h e f o r m of a c r u c i f o r m c l u s t e r . O p e r a t i o n s w e r e a n a l y z e d in s u p p o r t of m a k i n g t h e a b o v e c o n c e p t / c o n f i g u r a t i o n s e l e c t i o n s a s w e l l a s to p r o v i d e t h e b a s e s f o r m o r e d e t a i l e d d e f i n i t i o n of the RNS i t s e l f . During the second period m a j o r design activities w e r e oriented toward t r a d e studies selecting specific s u b s y s t e m design f e a t u r e s . To a c c o m p l i s h t h e s e t r a d e s t u d i e s , detailed o p e r a t i o n s a n a l y s i s , using the s c e n a r i o s developed during the f i r s t p e r i o d , •were p e r f o r m e d to e s t a b l i s h s u b s y s t e m r e q u i r e m e n t s . S u b s e q u e n t c h a r t s w i l l s h o w t h e o p e r a t i o n s a n a l y s i s and s u b s y s t e m d e f i n i t i o n for t h e RNS f u n c t i o n a l s u b s y s t e m s . T h i s s e c t i o n w i l l c o n c l u d e with a s u m m a r y of t h e m a j o r f e a t u r e s s e l e c t e d d u r i n g t h i s p e r i o d and v^ith t h e c u r r e n t w e i g h t s t a t e m e n t f o r b o t h RNS c o n c e p t s . 58
RNS DESIGN ® FIRST PERIOD RESULTS: ®RNS CONCEPT/CONFIGURATION ® CLASS 1 - - CCM FOR MAINTENANCE ® CLASS 3 - - CRUCIFORM CLUSTER ® OPERATIONS ® MISSION TIMELINE ^ORBITALASSEMBLY AND REFURBISHMENT ® RNS OPERATIONS ® SECOND PERIOD OBJECTIVES: • DESIGN FEATURE TRADE STUDIES ® DETAIL OPERATIONS TO ESTABLISH REQUIREMENTS 59
RNS P R O P E L L A N T M A N A G E M E N T A P P R O A C H T h i s p o r t i o n of t h e b r i e f i n g w i l l d e v e l o p t h e d e s i g n c o n c e p t and o p e r a t i o n s for t h e p r o p e l l a n t m a n a g e m e n t f u n c t i o n s of t h e R N S . F u n c t i o n a l s c h e m a t i c s w i l l b e d e v e l o p e d , b e g i n n i n g -with t h e m o s t b a s i c f u n c t i o n s r e q u i r e d f o r a s t a g e and a d d i n g s u b s y s t e m d e s i g n c o n c e p t s s p e c i f i c a l l y r e q u i r e d f o r RNS o r b i t a l and m i s s i o n o p e r a t i o n s . T h e a p p r o a c h w i l l b e to identify d e s i g n r e q u i r e m e n t s and i m p l i c a t i o n s of t h e v a r i o u s o p e r a t i o n a l p h a s e s . P r i o r to c o n a m e n c i n g t h e m i s s i o n t h e r e a r e o r b i t a l o p e r a t i o n s , i n c l u d i n g p r o p e l l a n t r e s u p p l y and c h e c k o u t , r e q u i r e d f o r r e u s a b i l i t y of t h e s y s t e m . T h e m i s s i o n o p e r a t i o n s f o r t h e r e f e r e n c e l u n a r s h u t t l e p r o f i l e e n c o m p a s s m u l t i p l e b u r n s in v a r i o u s N E R V A t h r u s t m o d e s . T h e a s s o c i a t e d o p e r a t i o n s a n d s e q u e n c i n g of t h e s t a g e f u n c t i o n a l s u b s y s t e m s w i l l be d e f i n e d f o r these requirements. 60
RNS PROPELLANT MANAGEMENT APPROACH DEVELOP RNS PROPELLANT MANAGEMENT SCHEMATIC ©BASIC FUNCTIONS # ADD DESIGN CONCEPTS FOR RNS ORBITAL & MISSION OPERATIONS IDENTIFY DESIGN REQUIREMENTS AND IMPLICATIONS OF RNS OPERATIONS PHASES # ORBITAL -• PROPELLANT RESUPPLY, CHECKOUT ® MISSION - LUNAR SHUTTLE PROFILE DEFINE FUNCTIONAL SUBSYSTEMS OPERATIONS & SEQUENCING # STARTUP # CONTROL # SHUTDOWN & AFTERCOOLING
BASIC P R O P E L L A N T M A N A G E M E N T S C H E M A T I C T h e b a s i c p r o p e l l a n t m a n a g e m e n t s c h e m a t i c s h o w s t h e p r o p u l s i o n m o d u l e and a s i n g l e p r o p e l l a n t m o d u l e . F u n c t i o n s a r e p r o v i d e d for g r o u n d , l a u n c h , and m i n i m u m m i s s i o n o p e r a t i o n s . T h e s t a g e i n t e r m o d u l e i n t e r f a c e s a r e flight r e m o t e couplings. G r o u n d fill a n d d r a i n for t h e C l a s s 3 m o d u l e s u s e s t h e e x i s t i n g p r o p e l l a n t feed s y s t e m for propellant loading inside the space shuttle. The propulsion module is l a u n c h e d d r y , h o w e v e r . T h e C l a s s 1-H p r o p e l l a n t m o d u l e i n c o r p o r a t e s a s e p a r a t e f i l l - a n d - d r a i n r i s e r duct, a pneumatically actuated, n o r m a l l y closed f i l l - a n d - d r a i n v a l v e , and a n u m b i l i c a l d i s c o n n e c t . T h e g r o u n d v e n t a n d r e l i e f s y s t e m p r o v i d e s f o r v e n t i n g of t h e fuel t a n k d u r i n g filling and s a f e t y r e l i e f c a p a b i l i t y in t h e e v e n t of i n a d v e r t e n t p r e s s u r e b u i l d u p . T h e s y s t e m c o n t a i n s a v e n t v a l v e and a v e n t - a n d - r e l i e f v a l v e . T h e v e n t v a l v e is p n e u m a t i c a l l y a c t u a t e d for g r o u n d o p e r a t i o n o n l y . G r o u n d v e n t f u n c t i o n s f o r t h e p r o p u l s i o n r a o d u l e a r e p r o v i d e d by field c o n n e c t i o n s t o t h e flight v e n t s y s t e m . T h e flight v e n t s y s t e m u t i l i z e s q u a d - r e d u n d a n t p i l o t - o p e r a t e d s o l e n o i d v a l v e s , which a r e p r e s s u r e s e n s o r controlled. Nonpropulsive vent n o z z l e s a r e incorporated. T h e p r e s s u r i z a t i o n s y s t e m o p e r a t e s with N E R V A b l e e d g a s . It u t i l i z e s a s e t of q u a d - r e d u n d a n t , d i r e c t - a c t i n g solenoid v a l v e s , which a r e p r e s s u r e s e n s o r c o n t r o l l e d . S e p a r a t e f u n c t i o n s of p r e p r e s s u r i z a t i o n , e x p u l s i o n , and p r e s s u r e control a r e provided. The p a r a l l e l redundant check valves a r e engine supplied. A d i f f u s e r i n l e t is i n c o r p o r a t e d . The p r o p e l l a n t feed s y s t e m p e r m i t s independent a c c e s s to each p r o p e l l a n t m o d u l e and i n d e p e n d e n t o p e r a t i o n of t h e p r o p u l s i o n m o d u l e . It c o n s i s t s of two p a r a l l e l 8. 0 0 - i n . - d i a m e t e r m o t o r - d r i v e n shutoff v a l v e s and a 12. 0 0 - i n . - d i a m e t e r b l o c k i n g v a l v e l o c a t e d in t h e f e e d t h r o u g h r i s e r . A n t i v o r t e x i n g and f i l t r a t i o n i s a c c o m p l i s h e d with tank bottom s c r e e n i n g . 62
18110 BASIC PROPELLANT MANAGEMENT SCHEMATIC FLIGHT VENT GROUND VENT/RELIEF, R GROUND FILL AND DRAIN # CLASS 1»H: PROVIDE DISCRETE SYSTEM ® CLASS 3: USE FEED SYSTEM ®PROPULSION: LAUNCH DRY GROUND VENT AND RELIEF ® PROPELLANT: DISCRETE ® PROPULSION: USE FLIGHT VENT FLIGHT VENT ®NON»PROPULSIVE PRESSURIZATION ® CONFIGURED FOR NERVA BLEED ® PROVIDE SEPARATE REPRESSURIZATION. EXPLUSION, AND CONTROL ® DIFFUSER INLET STAGE/ENGINE INTERFACE PROPELLANT FEED ® INDEPENDENT ACCESS TO MODULES PRESSURANT SUPPLY 63
P R O P E L L A N T RESUPPLY CONCEPT A schematic of the design concept for orbital propellant resupply is depicted in this c h a r t . It is used for orbital fill on both propellant and propulsion m o d u l e s . An objective of the design is to fill a propellant tank in orbit without venting or an e x c e s s i v e p r e s s u r e r i s e . This is accomplished by using s p r a y - n o z z l e injection to accomplish ullage c o l l a p s e , maintaining propellant orientation during the p r o p e l lant t r a n s f e r operation with axial a c c e l e r a t i o n provided by the tanker vehicle. Also, the orbital fill s y s t e m includes a check valve and a flow m e t e r in the fill line to control the propellant in-flow r a t e and m i n i m i z e p r e s s u r e s u r g e s during chilldown of a w a r m tank. This r e q u i r e m e n t is imposed on modules which have been depleted e a r l y in the m i s s i o n or have sustained a long coast in orbit before refill. The m a i n LH^ feed duct is blocked n e a r the top of the tank to limit p e n e t r a t i o n of cold fluid into the w a r m feed duct inside the tank during chilldown and inhibit g e y s e r i n g . The delivered propellant conditions at s t a r t u p of the RNS m i s sion depend on the propellant resupply logistics m o d e l . The v a r i a t i o n s introduced by such models will not be considered h e r e . F o r the s i m p l e s t c a s e , the difference between delivering the propellant to a w a r m and a cold tank is indicated. 64
18086 PROPELLANT RESUPPLY CONCEPT TANK FILLED WITHOUT VENTING FILL SHUT-OFF VALVES SPRAY NOZZLE INJECTION ACCELERATION BY TANKER PROVIDE CHILLDOWN OF WARM TANK CHECK VALVE & FLOW METER CONTROL MINIMIZE PRESSURE SURGES SPRAY NOZZLE FEED LINE BLOCKED CV DELIVERED PROPELLANT CONDITIONS 65 COLD TANK 16 PSIA WARM TANK - 21 PSIA
PROPELLANT M A N A G E M E N T CHECKOUT The r e q u i r e m e n t s for RNS propellant management checkout in orbit before s t a r t i n g the m i s s i o n consist of functional check of s u b s y s t e m s and components and leakage check at i n t e r f a c e s , which also includes initial verification of orbital a s s e m b l y . Candidate functional check approaches a r e delineated h e r e as either component functional checkout or actual simulated operations of the s y s t e m . A component functional checkout s t r a t e g y could m i n i m i z e fluid flow and expendables compared to simulated operations, while the l a t t e r could even r e q u i r e NERVA c r i t i c a l i t y to accomplish p r e s s u r i z a t i o n . In utilizing either approach it is d e s i r e d to impose m i n i m a l additional components or operations on the baseline design. 66
PROPELLANT MANAGEMENT CHECKOUT REQUIREMENTS # FUNCTIONAL CHECK - ALL SUBSYSTEMS AND COMPONENTS ® VERIFY OPERATION AND REDUNDANCIES # LEAKAGE CHECK AT INTERFACES ® STATIC SEALS ® DYNAMIC SEALS (VALVES) ® REMOTE FLUID COUPLINGS (ORBITAL ASSEMBLY) CANDIDATE FUNCTIONAL CHECK APPROACHES # COMPONENT FUNCTIONAL CHECKOUT ® OPERATE COMPONENTS SEQUENTIALLY - VERIFY TALKBACKS ® MINIMIZE FLUID FLOW AND EXPENDABLES # SIMULATED OPERATIONS ® PROPELLANT SETTLING, CHILLDOWN, PRESSURIZATION, RUN TANK REFILL, AFFERCOOLING ® NERVA CRITICALITY REQUIRED 67
COMPONENT FUNCTIONAL CHECKOUT Approaches to component functional checkout a r e defined h e r e for t h r e e general c l a s s e s of propellant management s u b s y s t e m configurations. F o r the f i r s t c l a s s , quad-redundant valve configurations, it is evident that redundancy has been imposed on m o s t flight s y s t e m s for reliability. Thus, no additional checkout valves a r e r e q u i r e d . The checkout approach consists of sequencing valve actuation to minimize fluid l o s s e s , verifying talkbacks from the c o n t r o l s . The approach r e q u i r e s independent control of the valves. The second c l a s s of propellant management s u b s y s t e m s is r e p r e s e n t e d by the LH2 feed s y s t e m . F o r this s y s t e m , blocking valves isolate each module interface, p e r m i t t i n g actuation of the dual feed v a l v e s . Similarly, the chilldown and refill pumps could be run with the d i s c h a r g e valves closed. These checkout operations could be p e r f o r m e d at convenient t i m e s in the operations profile, which include the propellant resupply period and the n o r m a l feed s y s t e m chilldown during the s t a r t u p r a m p to m i n i m i z e the impact of t h e s e o p e r a t i o n s . The third c l a s s of checkout items consists of ground-only functions such as the f i l l - a n d - d r a i n and ground vent s y s t e m s . These a r e locked for flight, and orbital checkout is not r e q u i r e d . 68
18101 COMPONENT FUNCTIONAL CHECKOUT C U S S 1: QUAD-REDUNDANT VALVE CONFIGURATIONS ® REDUNDANCY IMPOSED ON MOST FLIGHT SYSTEMS FOR RELIABILITY-ORBITAL FILL, PRESSURIZATION, FLIGHT VENT, CHILLDOWN, AFTERCOOLING, APS # NO ADDITIONAL C/0 VALVES REQUIRED # SEQUENCE ACTUATION TO MINIMIZE LOSSES ® VERIFY TALKBACKS ® REQUIRES INDEPENDENT CONTROL CLASS 2: LH2 FEED SYSTEM # BLOCKING VALVES ISOLATE EACH MODULE INTERFACE # ACTUATE DUAL FEED VALVES # RUN CHILLDOWN AND REFILL PUMPS WITH DISCHARGE VALVES CLOSED # PERFORM AT CONVENIENT TIMES ® PROPELLANT RESUPPLY ® FEED SYSTEM CHILLDOWN (STARTUP RAMP) CLASS 3: GROUND-ONLY FUNCTIONS (FILL AND DRAIN, GROUND VENT) # LOCKED FOR FLIGHT - ORBITAL C/0 NOT REQUIRED
PROPELLANT M A N A G E M E N T CHECKOUT APPROACH C o m p o n e n t f u n c t i o n a l c h e c k o u t is f a v o r e d o v e r s i m u l a t e d o p e r a t i o n s on the b a s i s of m i n i m i z i n g o p e r a t i o n a l p e n a l t i e s . F u r t h e r n a o r e , it i s e v i d e n t t h a t t h e r e a r e no m a j o r a d d i t i o n a l d e s i g n r e q u i r e m e n t s : s p e c i f i c a l l y , no c h e c k o u t v a l v i n g . T h e a d d i t i o n a l r e q u i r e m e n t s f o r o p e r a t i o n a l i n s t r u m e n t a t i o n and s t i m u l i a r e c o n s i d e r e d to b e s m a l l and the only v a r i a t i o n i m p o s e d on t h e d e s i g n is t h e r e q u i r e m e n t f o r p r o v i d i n g i n d e p e n d e n t v a l v e c o n t r o l in q u a d - r e d u n d a n t s y s t e m s . L e a k a g e c h e c k at i n t e r f a c e s c a n be a c c o m m o d a t e d by a n u m b e r of a p p r o a c h e s , w i t h t h e c o n s i d e r a t i o n t h a t t h e d e s i g n s h o u l d p r o v i d e i n s e n s i t i v i t y to s m a l l l e a k s . S e v e r a l p r a c t i c a l c a n d i d a t e s a r e a v a i l a b l e f o r l e a k a g e c h e c k of s e a l s . D u a l s e a l flanges and leak detection p o r t s have a l r e a d y been d e m o n s t r a t e d for static s e a l s on S - I V B . A c o u s t i c e m i s s i o n s e n s o r s a r e p r e s e n t l y b e i n g d e v e l o p e d f o r d y n a m i c s e a l s . F u r t h e r m o r e , it is c o n s i d e r e d t h a t o r b i t a l a s s e m b l y v e r i f i c a t i o n is feasible for the b a s e l i n e r e m o t e , automated a s s e m b l y o p e r a t i o n s . Torque control c a n be e m p l o y e d f o r s c r e w d r i v e s and p o s i t i o n o r t o r q u e t a l k b a c k s c a n b e employed. 70
PROPELLANT MANAGEMENT CHECKOUT APPROACH COMPONENT FUNCTIONAL C/0 FAVORED OVER SIMULATED OPERATIONS ^ M I N I M I Z E S OPERATIONAL PENALTIES # M I N I M A L DESIGN REQUIREMENTS ® NO C/O VALVING ® SMALL A STIMULI AND INSTRUMENTATION ® INDEPENDENT VALVE CONTROL LEAKAGE CHECK AT INTERFACES CAN BE ACCOMMODATED # DESIGN FOR INSENSITIVITY TO SMALL LEAKS # SEVERAL PRACTICAL CANDIDATES AVAILABLE ® STATIC: DUAL SEAL FLANGES AND LEAK DETECTION PORTS ® DYNAMIC: ACOUSTIC EMISSION SENSORS # ORB ITAL ASSEMBLY VERIFICATION FEASIBLE ® TORQUE CONTROL FOR SCREW DRIVES ® POSITION OR TORQUE TALKBACKS 71
RNS OPERATIONS FOR MISSION PHASES - I The propellant utilization and NERVA t h r u s t modes during the lunar shuttle m i s s i o n profile, which g e n e r a t e the stage propellant management design r e q u i r e m e n t s , a r e depicted in the next two c h a r t s for the C l a s s 3 RNS. These show the propellant loadings in the propellant modules and the propulsion m o d ule after completion of m a i n s t a g e b u r n s . Also, the aftercoolant r e q u i r e d after completion of the b u r n s is shown s e p a r a t e l y . In t h e s e figures the propulsion module is blown up in scale to provide g r e a t e r definition of the propellant loadings in that module. The capacity of a Glass 3 propellant module is 36,400 lb LH2 (8 a r e utilized) and the propulsion module capacity is 9, 700 lb LH2. The NERVA t h r u s t modes for the various m i s s i o n m a n e u v e r s a r e indicated. The first burn, t r a n s l u n a r injection (TLI), is p e r f o r m e d at full t h r u s t . The r e q u i r e d propellant for pulsed aftercooling is contained in the propulsion module run tank. The m i d - c o u r s e c o r r e c t i o n is p e r f o r m e d using the NERVA idle m o d e . Only the propulsion module is operated for that m a n e u v e r , so only that module is depicted. The initial elliptical lunar orbit injection m a n e u v e r (LOI-1) is also p e r f o r m e d at full t h r u s t . Since the run tank was depleted for TLI aftercooling and the m i d c o u r s e m a n e u v e r , it m u s t be refilled before L O I - 1 . The subsequent plane change m a n e u v e r at the moon (LOI-2) is p e r f o r m e d with the NERVA throttle mode, and all of the r e q u i r e d propellant for that maneuver and LOI~l aftercooling is contained in the run tank. Completion of lunar orbit injection {LOI-3) is p e r f o r m e d as a full t h r u s t operation, requiring a refill of the run tank before s t a r t u p . All aftercooling operations and the small m a n e u v e r s which a r e p e r f o r m e d at l e s s than full t h r u s t a r e p e r f o r m e d using only the propulsion module run tank. 72
18089 RNS OPERATIONS FOR MISSION PHASES-I r-s ^^ p^^^ PROPELLANT MODULES • ^ 1^^^:^ r^ ^-^ r^ N ^^ PROPULSION O MODULE ^^ BURN: MIDCOURSE LOI-1 LOI-2 LOI-3 THRUST: IDLE MODE FULL THROTTLE FULL MODE AFTERCOOLANT REQUIRED PROPELLANT REMAINING 73 1
RNS OPERATIONS FOR MISSION PHASES-II The remaining p h a s e s of the lunar shuttle m i s s i o n profile a r e depicted in this chart, including the t r a n s - e a r t h injection (TEI) and e a r t h orbit injection (EOI) m a n e u v e r s . The same general modes of operation a r e applied: t h r o t t l e mode for the plane change at the moon and idle mode for m i d - c o u r s e , with full-thrust operation in the main b u r n s . Again the propulsion module run tank supplies all of the aftercoolant and the propellant r e q u i r e d for small m a n e u v e r s . It is refilled before each full-thrust b u r n . 74
18090 RNS OPERATIONS FOR ^^ISSION PHASES-ii p^ N \^ .wvj PROPELLANT MODULES w PROPULSION MODULE n L^w^ i^ Q BURN: TEI-1 TEI-2 TEI-3 MIDCOURSE EOI THRUST: FULL THROTTLE MODE FULL IDLE MODE FULL AFTERCOOLANT REQUIRED PROPELLANT REMAINING 75
REQUIREMENTS FOR NERVA OPERATING MODES The NERVA t h r u s t modes d e s c r i b e d on the preceding c h a r t s g e n e r a t e r e q u i r e m e n t s for different stage propellant management functions, including propellant settling, feed s y s t e m chilldown, p r e p r e s s u r i z a t i o n , and p r e s t a r t run tank refill. The various NERVA t h r u s t operating modes a r e defined according to t h e i r r e s p e c t i v e p a r a m e t e r s and r e q u i r e d RNS functions in this c h a r t . These a r e used as a b a s i s for defining the RNS propellant management design concepts and o p e r a t i o n s . 76
18091 REQUIREIVIENTS FOR NERVA OPERATING MODES NERVA PARAMETERS RNS FUNCTIONS THRUST (LB) FLOW RATE (LB/SEC) ISP (SEC) FULL POWER 75,000 9L9 825 / / THRO! ILE MODE 45,000 55.1 825 / / 1,000 2 500 0.7 430 NERVA OPERATING MODE IDLE MODE AFTERCOOLING /= 300 PROPELLANT SETTLING REQUIRED 11 FEED SYSTEM CHILLDOWN PREPRESS" URIZATION / PRESTART RUN TANK REFILL ^l
STARTUP OPERATION PHASING SCHEMATIC The sequencing and i n t e r r e l a t i o n of the operations of propellant settling, propellant feed s y s t e m conditioning, NERVA t h r u s t buildup, and p r e p r e s s u r i z a t i o n of propellant tankage a r e delineated in this s c h e m a t i c . P r o p e l l a n t settling c o n s i s t s of two p h a s e s . The initial phase of inviscid orientation r e q u i r e s a low a c c e l e r a t i o n provided by the APS. This is followed by a h i g h - t h r u s t , dissipative settling p h a s e for which the n e c e s s a r y a c c e l e r a t i o n is provided by NERVA during its s t a r t u p r a m p . The operations for preconditioning the feed s y s t e m include chilldovAn and p r e s t a r t refilling of the run tank. These a r e a c c o m p l i s h e d during the inviscid orientation phase after an initial settling period. P r e p r e s s u r i z a t i o n cannot be initiated until completion of the dissipative phase of settling and NERVA cannot operate above the throttle point without tankage p r e p r e s s u r i z a t i o n , so a t h r u s t hold period at the throttle point is i n c o r p o r a t e d into the t h r u s t buildup r a m p . After p r e p r e s s u r i z a t i o n of the run tank the NERVA t h r u s t can be i n c r e a s e d to full power, although for some c a s e s it could be d e s i r a b l e to maintain the t h r u s t hold until completion of p r e p r e s s u r i z a t i o n of the propellant module. When the p r o pellant module is p r e s s u r i z e d , it can be brought on-line to refill the run tank under full power. The design concepts for each of t h e s e operations ^vill be defined in subsequent c h a r t s . 78
18092 STARTUP OPERATIONS PHASING SCHEfiATIC SYSTEM PROPELLANT SETTLING FEED SYSTEM DISSIPATIVE INVISCID ORIENTATION POWERED RUN TANK REFILL CCBPLETE RAMP CHILL-PRESTART RUN DOWN TANK REFILL BOOT STRAP THRUST HOLD FULL POWER RAMP TO THROTTLE POINT NERVA PRO RUN PELLANT TANK MODULE PREPRESSURIZATION 79
PROPELLANT SETTLING T h e p r o p e l l a n t s e t t l i n g o p e r a t i o n s a r e defined h e r e , d i v i d e d i n t o two p h a s e s . I n i t i a l l y , t h e r e is an i n v i s c i d o r i e n t a t i o n p h a s e to l o c a t e t h e p r o p e l l a n t at t h e b o t t o m of t h e t a n k s w h i l e i m p a r t i n g a m i n i m u m a m o u n t of k i n e t i c e n e r g y to i t . T h e c r i t e r i o n d e t e r m i n e d f o r t h e d e s i g n i s to p r o v i d e a n i n i t i a l r u n t a n k B o n d n u m b e r = 10 at T L I . ^JThis is p r o v i d e d jDy^3JLb^f_a_xiaJ^_£ettl_m_g_^^ A P S , c o r r e s p o n d i n g to a n i n i t i a l a c c e l e r a t i o n of 6. 7 x 10~o g. A n t i g e y s e r i n g .».^^„_.,__---»-^^.j^^^-£;^-~^ "Yg c o n t r o l . P r o v i d i n g s e t t l i n g f o r e a c h of t h e b u r n s in t h e l u n a r s h u t t l e m i s s i o n p r o f i l e r e s u l t s in a t o t a l i n v i s i d p h a s e s e t t l i n g p r o p e l l a n t c o n s u m p t i o n of 120 lb with a c r y o g e n i c A P S . D e f i n i t i o n of t h e s y s t e m h a s i n d i c a t e d n o i n t e r f e r e n c e of t h e s e t t l i n g t i m e s with l i m i t c y c l i n g o r a f t e r c o o l ing, e v e n t h o u g h t h e r e q u i r e d i n v i s c i d s e t t l i n g t i m e s a r e long, r a n g i n g f r o m 3, 200 s e c a t T L I to 1, 700 s e c for E O I w i t h t h e C l a s s 3 R N S . T h e s e c o n d p h a s e of s e t t l i n g r e q u i r e s h i g h t h r u s t to d i s s i p a t e t h e k i n e t i c e n e r g y of t h e fluid, d a m p out s l o s h and e l i m i n a t e b u b b l e s . S l o s h baffles a r e i n c o r p o r a t e d to a s s i s t e n e r g y d i s s i p a t i o n . T h e o b j e c t i v e for t h i s p h a s e i s to a c h i e v e a q u i e s c e n t l i q u i d to p e r m i t e f f i c i e n t p r e p r e s s u r i z a t i o n w i t h a hot g a s . T h e m o s t e f f i c i e n t d e s i g n c o n c e p t i s to u t i l i z e the N E R V A t h r u s t r a m p a n d t o hold t h e t h r u s t a t t h e t h r o t t l e p o i n t until a d e q u a t e s e t t l i n g for p r e p r e s s u r i z a t i o n h a s b e e n a c h i e v e d . U s i n g e x i s t i n g c r i t e r i a t h i s r e q u i r e s 10 to 60 s e c for t h e r a n g e of s t a r t u p c o n d i t i o n s in t h e m i s s i o n . 80
18094 PROPELLANT SETTLING INVISCID ORIENTATION PHASE # CRITERION: UTILIZE APS: GEYSERING BAFFLE-7 INITIAL RUN TANK BOND NO. = 10 3 LB THRUST, 120 LB PROPELLANT TOTAL NO INTERFERENCE OF SEHLING TIMES WITH LIMIT CYCLING OR AFTERCOOLING: SLOSH BAFFLES TLI 3,200 SEC, E O I I , 700 SEC DISSIPATIVE PHASE # CRITERION: ELIMINATE SLOSH & BUBBLES FOR PREPRESSURIZATION UTILIZE NERVA THRUST RAMP - POSSIBLE HOLD AT THROTTLE POINT REQUIRES 10 TO 60 SECONDS 81
NERVA STARTUP THRUST R A M P NERVA operating conditions, a c c e l e r a t i o n level, and the r e q u i r e d saturation p r e s s u r e for 0 N P S P at the existing flow r a t e a r e indicated at v a r i o u s t i m e s through the NERVA t h r u s t buildup r a m p . After the first 30 sec of b o o t s t r a p operation, the a c c e l e r a t i o n level b e c o m e s adequate for the dissipative r e q u i r e m e n t s of settling. It is seen that the engine can operate up to the t h r o t t l e point without p r e p r e s s u r i z a t i o n for the anticipated propellant h i s t o r i e s , since tank chilldown r e s u l t s in a 21-psia initial condition. 82
NERVA STARTUP THRUST RAMP PHASE BOOTSTRAP RAMP UP 18095 TIME fSEC) FLOW RATE (LB/SEC) 0 12 295 253 6.3X10"^ 12 25 L2 383 331 8.1 X 10-4 12 30 L8 691 375 L 5 X 10-3 •12 39 218 17,0% 572 3,6X10-2 16.2 52 55 J 44,9% 816 16X10-2 203 THROTTLE POINT 56 9L9 75,000 816 0J6 26.0 FULL THRUST THRUST iSP ACCELERATION (LB) (SEC) ^ FULL RNS AT TLI 83 PSAT FOR ONPSP (PSIA)
CHILLDOWN REQUIREMENTS P r i o r to s t a r t u p it is n e c e s s a r y to chilldown the active portion of the RNS feed s y s t e m to a s s u r e propellant conditions for NERVA and to a c c o m p l i s h a p r e dictable s t a r t u p operation. The feed s y s t e m interfaces that r e q u i r e conditioning include the two legs of the NERVA feed s y s t e m between the turbopump and the run tank and the interfaces between the various RNS m o d u l e s . These a r e s u m m a r i z e d in the facing c h a r t . All the stage feed ducting uses two basic types of flexible e l e m e n t s , gimbal joints and linear p r e s s u r e volume c o m p e n s a t o r s , which account for the m a s s e s shown for those s y s t e m s . Chilldown t i m e r e q u i r e m e n t s w e r e based on the m i n i m a l p e r m i s s i b l e t i m e for chilldown of each interface c o n s i d e r i n g film boiling heat t r a n s f e r for a duct initially at ambient t e m p e r a t u r e and providing a m a r g i n of safety for flow s u r g e s . 84
18096 CHILLDOWN REQUIREI^ENTS CHILL TIME (SEC) INItRFACE CCBPONENTS MASS (LB) LENGTH (FT) EQUIVALENT BOILOFF (LB-LH2) NERVA (EACH SIDE) PSOV-VALVE 9 IN, FEED DUCT* TURBOPUMP PDKVA-VALVE 973 8,9 92 43 RUN TANK/ PROPELLANT MODULE 12 IN. FEED DUCT* 263 11 28 34 PROPELLANT MODULE/ PROPELLANT MODULE 12 IN, FEED DUCT* 217 10»2 23 24 OUTBOARD/ INBOARD PROPELLANT MODULES 8 IN. FEED DUCT* 116 1L5 13 17 * INCLUDES GIMBAL JOINTS
INTEGRATED NERVA/STAGE CHILLDOWN SYSTEM This c h a r t depicts the s c h e m a t i c of the integrated N E R V A / s t a g e pump driven chilldovm s y s t e m for p r e s t a r t chilldown of the propellant feed s y s t e m . It is l o cated in the run tank and provides conditioning for both the NERVA and stage i n t e r f a c e s . It is operated during the low-g inviscid orientation phase of settling to avoid s e p a r a t e o p e r a t i o n s . F o r c e d convection is r e q u i r e d for the low-g chilldown. The indicated schematic is compatible vv^ith the c u r r e n t NERVA interface. The propulsion module run tank contains redundant, submerged, a c - m o t o r - d r i v e n centrifugal p u m p s . An i n v e r t e r is provided for each motor to utilize the dc power b u s . Each pump is sized for full chilldov/n s y s t e m capacity, amounting to 2 lb LH2 per second. The dominant p r e s s u r e drop is in the NERVA turbopump (about 3.5 psi). This r e s u l t s in a pump power of about 1 HP. Fluid r e t u r n for stage feed duct chilldown is accomplished with the refueling s p r a y nozzle bypass s y s t e m on the run tank. Fluid r e t u r n for the NERVA feed chilldown is provided by a s e p a r a t e gimbaled r e t u r n line and shutoff v a l v e s . Check valving is located at all injection points to prevent s u r g e s and d i s t u r b a n c e s from being t r a n s m i t t e d to the adjoining systenns. The indicated design is a variation on the chilldown s y s t e m concept which has been proven in flights on the S-IVB. 86
18087 INTEGRATED NERVA / STAGE CHILLDOWN SYSTEM PROPELLASiT FEED SYSTEM CSCV CSOV SYSTEM LOCATED IN RUN TANK CHILLOOWf^ SHUT-OFF VALVES CONDITIONS NERVA & STAGE INTERFACES OPERATE DURING LOW-G SETTLING • FORCED CONVECTION REQUIRED UTILIZE REDUNDANT AC SUBMERGED PUMPS • 2LB-LH2/SEC • 1 HP DESIGN MINIMIZES PRESSURE SURGES • CONCEPT PROVEN ON S-IVB 87
P R E S T A R T RUN TANK R E F I L L S Y S T E M It w a s e x p l a i n e d in t h e d e f i n i t i o n of t h e m i s s i o n o p e r a t i o n s p r o f i l e t h a t it i s n e c e s s a r y to r e f i l l t h e r u n t a n k b e f o r e s t a r t u p f o r a l l full p o w e r b u r n s . T h e s y s t e m f o r a c c o m p l i s h i n g r e f i l l is d e s c r i b e d h e r e . T h e o b j e c t i v e s in t h e d e s i g n of the s y s t e m a r e to a v o i d v e n t i n g , to a c c o m m o d a t e a h i g h e r p r e s s u r e in r u n t a n k t h a n in t h e p r o p e l l a n t m o d u l e s u p p l y , t o i n t e g r a t e t h e r e f i l l o p e r a t i o n w i t h t h e n o r m a l s e q u e n c e of s t a r t u p o p e r a t i o n s ( a v o i d i n g s e p a r a t e o p e r a t i o n a l r e q u i r e m e n t s ) , and to p r o v i d e for d e l i v e r y of up to 8, 500 lb of LH2 d u r i n g t h e r e f i l l o p e r a t i o n . A s d e p i c t e d in t h e s t a r t u p o p e r a t i o n p h a s i n g s c h e m a t i c , t h e r e f i l l o p e r a t i o n w i l l b e p h a s e d s u b s e q u e n t to t h e feed s y s t e m c h i l l d o w n . T h e s y s t e m c o n c e p t d e f i n e d in t h i s s c h e m a t i c u s e s r e d u n d a n t , a c s u b m e r g e d p u m p s l o c a t e d in the r u n t a n k w i t h a c a p a c i t y of 5 lb LH2 p e r s e c o n d a n d a p o w e r of 1 H P , T h e b a s e s u m p f o r t h e p u m p s i s l o c a t e d in t h e m a i n feed d u c t a n d t h e p u m p s d i s c h a r g e t h r o u g h t h e c o n v e n t i o n a l o r b i t a l fill s y s t e m . T h e d e s i g n a p p r o a c h w o u l d i n t e g r a t e t h e r e f i l l s y s t e m with t h e c h i l l d o w n s y s t e m by u t i l i z i n g s i n g l e - m o t o r , double-ended pumps. 88
18088 PRESTART RUN TANK REFILL SYSTEM ~"""^"\/~SPRAY DESIGN OBJECTIVES • NO VENTING • ACCOMMODATE HIGHER PRESSURE IN RUN TANK • INTEGRATE REFILL WITH STARTUP • UP TO 8,500 LB-LH2 REQUIRED LH2 REFILL PUMP- PHASE WITH FEED SYSIIM CHILLDOWN UTILIZE REDUNDANT AC SUBMERGED PUMPS • 5LB-LH2/SEC REFILL SHUT-OFF VALVES • IHP INTEGRATE HARDWARE WITH RUN TANK SYSTEMS • CHILLDOWN • ORBITAL FILL 89
SUMMARY OF RUN TANK DEPLETION DURING STARTUP Although the run tank o p e r a t e s independently during the s t a r t u p operation, it is d e s i r a b l e to avoid depleting its propellant level too g r e a t l y b e c a u s e of i n c r e a s e d radiation dosage to equipment located at the top of the propulsion module. The nominal run tank capacity is 9, 500 lb of LH2 and typically it is d e s i r a b l e to keep the run tank level above 5, 000 lb of LH2, where the dose r a t e is a factor of 2 higher than for the full tank. The m i n i m u m run tank level (or depletion) during the startup operations is s u m m a r i z e d in this figure for the m i s s i o n profile. The duration of the NERVA t h r u s t hold to complete propellant settling and tankage p r e p r e s s u r i z a t i o n operations is also indicated in the figure. The resulting m i s s i o n p e r f o r m a n c e penalties a r e negligible. To avoid e x c e s s i v e depletion of the run tank for the two initial b u r n s , it proved d e s i r a b l e to hold the t h r u s t at the throttle point until completion of p r e p r e s s u r i z a t i o n . The resulting reduced flow r a t e before the propellant module could be brought on-line avoids e x c e s s i v e run tank depletion. After the propellant module is brought on-line, the run tank will be refilled during full pov/er with the p r e s s u r e head differential between the tanks by reducing the impedance of the flow control valve from its s t e a d y - s t a t e setting. 90
18097 SUMMARY OF RUN TANK DEPLETION DURING STARTUP CLASS 3 RNS BURN NERVA THRUST HOLD (SEC) PROPELLANT TANK PREPESSURIZATION TIME (SEC) RUN TANK DEPLtllON (LB-LH2) MINIMUM TANK LEVEL (LB-LH2) TLI 67* 23 4,430 * 5,260* LOI-1 59* 31 3,990 * 5,700* LOI-3 27 26 4,620 5,070 TEhl 18 7 2,380 7,310 TEh3 16 30 4,390 5,300 EOI 14 28 4,090 5,600 * THRUST HOLD THRU PROPELLANT TANK PREPRESSURIZATION CONCLUSION? SUFFICIENT PROPELLANT FOR SHIELDING CAN BE MAINTAINED
TANK PRESSURE AND LIQUID L E V E L CONTROL SCHEMATIC The p r e s s u r i z a t i o n control s y s t e m schenaatic shown u s e s independent p r e s s u r e and flow control for the propulsion and propellant m o d u l e s . The bang-bang p r e s s u r e control systein c o n s i s t s of p a r a l l e l redundant, n o r m a l l y closed shutoff v a l v ing that a r e controlled by s t r a i n gage p r e s s u r e t r a n s d u c e r s located in the tank u l l a g e s . A s e p a r a t e s t e a d y - s t a t e expulsion p r e s s u r i z a t i o n leg is provided. The propellant module s y s t e m r e q u i r e s a t h i r d operating range for the l a r g e p r e p r e s surization flow r e q u i r e m e n t and the full power run tank refill o p e r a t i o n . The flow control s y s t e m consists of two 8 - i n . - d i a m e t e r throttle v a l v e s . These m o t o r driven throttle valves a r e controlled by sensing liquid level in the run tank. T h r e e d i s c r e t e liquid-level s e n s o r s provide the control signal based on a voting c i r c u i t . O v e r p r e s s u r i z a t i o n is prevented by the baseline quad-redundant flight vent s y s t e m . 92
18111 TANK PRESSURE AND LIQUID LEVEL CONTROL SCHEfVlATiC COMTROL I j INDEPENDENT CONTROL OF MODULE PRESSURES •'y%i n. ® STRAIN-GAGE PRESSURE TRANSDUCERS #BANG"BANG PRESSURE CONTROL VALVES PRESSURIZATION, VENT PRESSURIZATION 0 @ @ EXPULSION CONTROL PREPRESS, i n-HONLY) ® SEPARATE EXPULSION PRESSURIZATION ®PREPRESSURIZATION CONTROL,. ^ FLIGHT VENT CLASS 3: USE EXPULSION CLASS 1»H: REQUIRE DISCRETE SYSTEM RUN TANK LIQUID LEVEL CONTROL ^OPTICAL POINT LEVEL SENSORS # SERVO-CONTROL FEED VALVES 93
TANK PRESSURE AND LIQUID L E V E L CONTROL SIMULATION The dynamics of the b a s e l i n e control s y s t e m have been investigated to e s t a b l i s h s y s t e m r e s p o n s e s and controller c h a r a c t e r i s t i c s . The simulation shown h e r e evaluated the operation of the LH2 feed valve c o n t r o l l e r as it responded only to liquid-level height without additional information as to the r a t e or d i r e c t i o n of level change. The following t r a n s i e n t operations a r e p r e s e n t e d : (1) the propellant loading in the run tank was i n c r e a s e d from 6, 000 to 9, 000 lb while supplying full flow to the engine, (2) a step i n c r e a s e of 0.2 p s i was imposed in the propellant module p r e s s u r e to simulate p r e s s u r a n t changes or a c c e l e r a t i o n head changes within the propellant module, and (3) a drop in the demand of the flow r a t e to the engine to respond to the e m e r g e n c y mode condition. The run tank refill c a s e shows an i m m e d i a t e r e q u i r e m e n t to vent the run tank after the LH2 feed valve is opened. The p r e s s u r e adjustment reduced the flow r a t e from its initial refill v a l u e . Upon reaching 9, 000 lb, the command was given to i n c r e a s e the control valve impedance to its s t e a d y - s t a t e value. The p r e s s u r e s within the propellant module and propulsion run tank show the anticipated s e l f - r e g u l a t i n g characteristics. Next, a 0. 2 - p s i a p r e s s u r e p e r t u r b a t i o n was introduced in the propellant m o d e . F o r the other functions this is c o m p a r a b l e to a head change upon switching p r o pellant m o d u l e s . The r e s u l t i n g i n c r e a s e in the p r e s s u r e of the r u n tank quickly damped out the p e r t u r b a t i o n . Finally, the NERVA e m e r g e n c y mode was applied. The feed valve c o n t r o l l e r responded and achieved the new 60-lb flow r a t e after the propellant in the run tank had i n c r e a s e d an additional 150 l b . Oscillations w e r e obtained around the 9, 200-lb level b e c a u s e the feed valve c o n t r o l l e r was responding to the liquid level s e n s o r before the self-regulating c h a r a c t e r i s t i c s of the p r e s s u r e s in the run tank and the propellant tank could damp out these o s c i l l a t i o n s . This effect is only caused by the simplified control model used for the simulation. 94
18129 TANK PRESSURE AND LIQUID LEVEL CONTROL SIMULATION PRESSURE CONTROL SETTINGS (PSIA): PRESSURANT VENT PROPULSION 26.2 26.5 PROPELLANT 27.7 28.0 LIQUID LEVEL CONTROL SETTINGS: ® 9,000 LB-LH2 NORMAL SETTING ® A IMPEDANCE = 10% PER 50 LB-LH2 100 200 TIME (SEC) RNS OPERATION SIMULATION 95
SHUTDOWN OPERATIONS PHASING SCHEMATIC The relationship of the shutdown operations for NERVA and the propellant and propulsion module propellant management s y s t e m s is shown in this s c h e m a t i c . The t h r u s t level is reduced from full power to the throttle point naaintaining all s y s t e m s in operation. At this point, typically, the propellant module is isolated, terminating the r e q u i r e m e n t for p r e s s u r i z a t i o n and feed s y s t e m operation for the propellant naodule. During the t e m p e r a t u r e r e t r e a t phase of NERVA, propellant feed is maintained through the n o r m a l NERVA feed s y s t e m . Run tank p r e s s u r i z a t i o n can be t e r m i n a t e d at the t h r o t t l e point or continued through the t e m p e r a t u r e r e t r e a t if d e s i r e d . After pump tailoff, the s e p a r a t e aftercooling bypass s y s t e m is actuated to provide aftercooling p u l s e s . 96
18093 SHUTDOWN OPERATIONS PHASING SCHEMATIC SYSTEM FULL POWER THROTTLE NERVA TEMPERATURE RETREAT PUMP TAILOFF AFTERCOOLING PROPELLANT MODULE PRESSURIZATION FFFD PROPULSION MODULE PRESSURIZATION FEED PULSES AFTERCOOLING BYPASS 97
AFTERCOOLING SYSTEM The baseline aftercooling s y s t e m concept is depicted in this s c h e m a t i c . It employs a surface tension pulse basket to provide liquid to the NERVA a f t e r cooling bypass s y s t e m . T h e r e a r e no operations imposed on the RNS for e i t h e r propellant settling or p r e s s u r i z a t i o n with this concept. Only the run tank is employed for aftercooling pulse o p e r a t i o n s . 98
AFTERCOOLING SYSTEM SURFACE TENSION PULSE BASKET MAIN TANK SCREEN # LIQUID FEED # NO PROPELLANT SETTLING # NO PRESSURIZATION COURSE MESH SCREEN USE ONLY RUN TANK PRESSURE EQUALIZATION LINE AFTERCOOLING BYPASS DUCT 99
RNS P R O P E L L A N T MANAGEMENT SUMMARY AND CONCLUSIONS To review the portion of the briefing j u s t completed, the operations and design r e q u i r e m e n t s for the RNS propellant management systenns have been e s t a b lished for the lunar shuttle m i s s i o n profile. System design concepts, o p e r a t i o n s , and sequencing have been defined for each of the r e q u i r e d o p e r a t i o n s , including those in orbit p r i o r to operation of the RNS and those r e q u i r e d during n o r m a l r a i s sion o p e r a t i o n s . The s u b s y s t e m design concepts which have been identified a r e feasible and supported by proven S-IVB design a p p r o a c h e s . A question r e m a i n s concerning component lifetimes for the long duration, high life cycle naission r e q u i r e m e n t s . It should be e m p h a s i z e d that o r b i t a l e x p e r i m e n t s will be r e q u i r e d e a r l y in the p r o g r a m to refine the design c r i t e r i a imposed on the operations of the identified s y s t e m s . Included among the i s s u e s a d d r e s s e d h e r e a r e c r i t e r i a for propellant settling, chilldown heat t r a n s f e r , p r e s s u r i z a t i o n r e q u i r e m e n t s , and aftercooling s y s t e m o p e r a t i o n s . 100
18099 RNS PROPELLANT MANAGEMENT SUMMARY AND CONCLUSIONS OPERATIONS AND DESIGN REQUIREMENTS ESTABLISHED FOR LUNAR SHUTTLE MISSION SYSTEM DESIGN CONCEPTS, OPERATIONS, & SEQUENCING DEFINED ® PROPELLANT RESUPPLY ®CHECKOUT ® STARTUP: PROPELLANT SEHLING, CHILLDOWN, RUN TANK REFILL # PRESSURE & RUN TANK LH2 LEVEL CONTROL # SHUTDOWN & AFTERCOOLING SELECTED DESIGN CONCEPTS FEASIBLE # COMPONENT LI FETIMES TO BE ESTABLI SHED # RNS DESIGN BASIS SUPPORTED BY S-IVB ORBITAL EXPERIMENTS WILL BE REQUIRED TO REFINE DESIGN CRITERIA
ASTRIONICS APPROACH The s y s t e m r e q u i r e m e n t s for a s t r i o n i c s w e r e e s t a b l i s h e d . The b a s e l i n e RNS m i s s i o n r e q u i r e m e n t s w e r e utilized together with RNS operations i n c u r r e d during all m i s s i o n p h a s e s . Several candidate a p p r o a c h e s w e r e e s t a b l i s h e d for each subsystena. These approaches w e r e evaluated and the s u b s y s t e m c h a r a c t e r i s t i c s d e t e r m i n e d . Special attention was paid to the onboard checkout function, including the relationship of checkout and the maintenance s t r a t e g y . Additionally, the sequence of checkout operations was e s t a b l i s h e d . The c h a r a c t e r i s t i c s of r e l a t i v e d e g r e e s of autonomy for the guidance and navigation s u b s y s t e m w e r e e s t a b l i s h e d . The data m a n a g e m e n t function v/as evaluated in the context of t h r e e s e p a r a t e types of r e q u i r e m e n t s . The r e q u i r e m e n t s for communication between the RNS and ground w e r e established. Additionally the p r o c e s s i n g and s t o r a g e r e q u i r e m e n t s for the onboard p r o c e s s e r w e r e quantified. This included a review of all s u b s y s t e m and RNS r e q u i r e m e n t s . A l t e r n a t e data b u s e s w e r e c o n s i d e r e d and the traffic on the RNS data bus d e t e r m i n e d . An a r c h i t e c t u r e for the RNS data bus w^as established. 102
ASTRIONICS APPROACH # ESTABLISH SYSTEM REQUIREMENTS MISSION RNS OPERATION # IDENTIFY CANDIDATE APPROACHES ® EVALUATE AND SELECT SYSTEM CHARACTERISTICS ONBOARD CHECKOUT GUIDANCE AND NAVIGATION DATA MANAGEMENT ® PROCESSING ©COMMUNICATION ® DATA BUS 103
RNS MODULE DEFINITION T h r e e distinct modules have been identified. The Comimand and Control Module contains the e n t i r e navigation, guidance and control function including the s e n s o r s and p r o c e s s i n g capability r e q u i r e d to i m p l e m e n t autonomous navigation. The p r i m a r y po-wer source is also included in the Command and Control Module as well as the a u x i l i a r y propulsion s y s t e m . The m a j o r components of NDICE a r e physically contained in the Command and Control Module communicating to the propulsion module via the data b u s . The propellant module contains a m i n i m u m amount of h a r d w a r e and capability. The function is limited to hydrogen storage and only that h a r d w a r e needed to implement this function is included. The propulsion module includes the run tank and a m i n i m u m of a s t r i o n i c s equipment which is effectively shielded from the radiation environment by the run tank. Multiplexing and signal conditioning of i n s t r u m e n t a t i o n and conamand decode is included on this module. 104
RNS fVIODULE DEFINITION COMMAND AND CONTROL MODULE ® NAVIGATION, GUIDANCE AND CONTROL ® DATA PROCESSING # POWER # AUXILIARY PROPULSION # NDICE PROPELLANT MODULE(S) ® PROPELLANT STORAGE ONLY ® MINIMUM CAPABILITY PROPULSION MODULE ® NERVA RELATED FUNCTIONS ONLY ® RUN TANK FOR OPERATION 105
RNS ONBOARD CHECKOUT The maintenance s t r a t e g y defines ground r e c y c l e for the Command and Control Module after each m i s s i o n . Space shuttle t r a n s p o r t a t i o n is postulated. Replenishment of expendables for the fuel cells and the a u x i l i a r y propulsion s y s t e m a r e accomplished on the ground. Scheduled maintenance operations will be p r o g r a m m e d as r e q u i r e d . The p r i m a r y checkout functions, including calibration, will be accomplished using the onboard checkout capability aided by ground support equipment. The Command and Control Module includes h a r d w a r e r e q u i r e d to perform onboard checkout. The onboard checkout s y s t e m will be designed to accomplish orbital checkout. All other functions r e q u i r e d during the r e c y c l e operation will be supplied by ground support equipment. All p r o c e d u r e s a r e stored and p r o c e s s i n g is accomplished by the c e n t r a l i z e d p r o c e s s e r in the data m a n a g e m e n t s u b s y s t e m . The NDICE included in the Command and Control Module will effect checkout of the NERVA. The propellant module will utilize the capa ~ bility of the onboard checkout s y s t e m in the Command and Control Module to verify its flight r e a d i n e s s . Since the propellant module is a space r e s i d e n t e l e m e n t , all fault prediction capability is included. The propulsion module also being space r e s i d e n t will have the sanae c h a r a c t e r i s t i c requirenaents for checkout as the propellant m o d u l e s . Additionally, the NERVA engine checkout will be p e r f o r m e d by NDICE, 106
RNS ONBOARD CHECKOUT ® COMMAND AND CONTROL MODULE GROUND REFURBISHMENT EACH MISSION ® REPLENISHMENT OF EXPENDABLES ® SCHEDULED MAINTENANCE ® CHECKOUT AND CALIBRATION - GSE SUPPORT CHECKOUT CONTROL FOR ALL MODULES ® PROCESSING AND PROCEDURES ® NDICE FOR NERVA ® PROPELLANT MODULE(S) ® FLIGHT READINESS ® FAULT PREDICTION ® PROPULSION MODULE ® STAGE SUBSYSTEMS ® NERVA-NDICE 107 SAME AS PROPELLANT MODULE
ONBOARD CHECKOUT SEQUENCE F o u r d i s c r e t e p h a s e s of checkout can be identified: (1) during orbital a s s e m b l y (prior to the first nnission) or r e f u r b i s h m e n t (after subsequent m i s s i o n s ) . A s s e m b l y verification of those modules that a r e involved in a s s e m b l y (including pay load) will be m a d e . Rechecks on all broken fluid connections and on the dynamic s e a l s of all c r i t i c a l valves will be m a d e . The interface between modules and specific s u b s y s t e m s which a r e b e s t checked during this phase of the operation will be verified. (2) During the orbital countdown all s u b s y s t e m and component checkout will occur, including the verification of all redundancies for space r e s i d e n t m o d u l e s . This will be a c c o m p l i s h e d by the s y s t e m a t i c p e r f o r m a n c e of a s e r i e s of p r o c e d u r e s stored in the data manageraent s u b s y s t e m . The combination of this s e r i e s of p r o c e d u r e s 'will verify the vehicle is ready for flight. (3) during the operational phase of the m i s s i o n continuous s t a t u s , monitoring of a limited set of functions will o c c u r . The status of these functions will be c o m p a r e d to soine p r e d e t e r m i n e d standard to e n s u r e that the vehicle health is as expected. During the operational phase, data m u s t be collected to a c c o m p l i s h fault prediction and a limited amount of trend a n a l y s i s will be p e r f o r m e d on line. (4) Follovv'ing the m i s s i o n the fault prediction data will be utilized to d e t e r m i n e the potential of impending failures on space r e s i d e n t h a r d w a r e and the ground will p r o c e s s the m i s s i o n data to d e t e r m i n e unforeseeable a n o m a l i e s . 108
ONBOARD CHECKOUT SEQUENCE DURING ASSEMBLY/REFURBISHMENT # # # # ASSEMBLY VERIFICATION LEAK CHECKS MODULE INTERFACE CHECKS SPECIFIC SUBSYSTEMS ORBITAL COUNTDOWN # SUBSYSTEM AND COMPONENT CHECKOUT # VERIFY ALL REDUNDANCIES # VEHICLE FLIGHT READINESS OPERATIONAL PHASE # STATUS MONITORING # FAULT PREDICTION DATA COLLECTION FOLLOWING MISSION ® FAULT PREDICTION # GROUND PROCESSING OF MISSION DATA 109
ONBOARD CHECKOUT REQUIREMENTS Reviewing the v a r i o u s s u b s y s t e m s , o r b i t a l checkout, and utilizing S-IVB t e s t data, it is e s t i m a t e d that 25, 000-word s t o r a g e will be r e q u i r e d for the checkout p r o c e d u r e s . This includes both s u b s y s t e m and e m e r g e n c y p r o c e d u r e s . Although the bulk of the p r o c e d u r e s a r e p e r f o r m e d off of peak data p r o c e s s i n g load time (orbital operations or coast m o d e s ) , t h e r e is a r e q u i r e m e n t to p e r f o r m specific operations during peak which is anticipated to be during engine b u r n . Reviewing those functions that m u s t be p e r f o r m e d during peak, a total of 8, 200 equivalent adds per second (ops) have been identified. T h e s e include p r i m a r i l y the data management self check p r o c e d u r e s that is guaranteeing the health of the p r o c e s s o r and the trend analysis to detect impending failures which potentially preclude an e m e r g e n c y situation. Additionally, a s m a l l amount of p r o c e s s i n g will be utilized for the g e n e r a l health monitor or status monitoring capability included in the data m a n a g e m e n t functions, A review of specific s u b s y s t e m s indicates that with r a r e exception the existing vehicle operational data acquisition capability can be used as a p r i m a r y data s o u r c e to evaluate the p e r f o r m a n c e of each s u b s y s t e m during the checkout p h a s e . Additionally, the control to stimulate these s u b s y s t e m s / components can be effected by the nominal control lines of the RNS. A m i n i m u m of additional i n s t r u m e n t a t i o n and control will be r e q u i r e d . Exceptions to this a r e the r e q u i r e m e n t that position indications be supplied for all components to verify the p e r f o r m a n c e of the component upon stimulation and d i s c r e t e i n s t r u m e n t a t i o n and control be provided for all r e d u n d a n c i e s . B e c a u s e CCM checkout is a s s i s t e d by ground support equipment, the addition of t e s t connectors will be r e q u i r e d for a c c e s s to c r i t i c a l t e s t points for the verification of this s u b s y s t e m and the associated redundancies. 110
ONBOARD CHECKOUT REQUIREMENTS ® PROCEDURES STORAGE " - 25,000 WORDS ® PROCESSING REQUIREMENTS VEHICLE CHECKOUT OFF PEAK 8,200 OPERATIONS/SEC AT PEAK ® DATA MANAGEMENT SELF CHECK ® FAULT PREDICTION ® STATUS MONITORING ® PRIMARY DATA AND CONTROL VIA RNS OPERATIONAL CHANNELS ®ADD POSITION INDICATION TO COMPONENTS # DISCRETE INSTRUMENTATION AND CONTROL FOR REDUNDANCIES ® TEST CONNECTORS ON CCM 111
GUIDANCE AND NAVIGATION C A N D I D A T E S T h r e e c o n c e p t s w e r e d e v e l o p e d . E a c h of w h i c h r e p r e s e n t s a d i f f e r e n t d e g r e e of autononny f o r the g u i d a n c e and n a v i g a t i o n s u b s y s t e m . . T h e f i r s t c o n c e p t , a u t o n o m o u s g u i d a n c e and n a v i g a t i o n , is c h a r a c t e r i z e d by a l a n d m a r k t r a c k e r in a d d i t i o n to the s t a r t r a c k e r s , an IMU, and a h o r i z o n s e n s o r w h i c h a r e r e q u i r e d f o r a l l c a n d i d a t e s . In t h e c a s e of the a u t o n o m o u s c o n c e p t , t h e c a p a b i l i t y f o r g r o u n d t r a c k ing a s a b a c k u p w a s i n c l u d e d . JILh:e_us^e__o£_Tmvi^ay.qn_s_a or ground beacons j^s^_c_onjjd_ereji_a^ttractive_fprJ;h,e sga£e_shuttj.e. B e c a u s e of the l i k e l y e x i s t e n c e of t h i s c a p a b i l i t y d u r i n g RNS o p e r a t i o n s , it w a s i n c l u d e d as a c a n d i d a t e in the g u i d a n c e _majk_t3La£jS£-r__ajad^,U.bAtitutioji of a ran^ing^ r ^ Tbe^Jiffi^uJlxJSdthjy^^ l i e s in the r e q u i r e m e n t s for a n a v i g a t i o n aid in l u n a r o r b i t . T h e t h i r d c a n d i d a t e is c h a r a c t e r i s t i c of the A p o l l o a p p r o a c h of g r o u n d t r a c k i n g and is c h a r a c t e r i z e d by the u s e of the M a n n e d S p a c e F l i g h t N e t w o r k (MSFN) on the g r o u n d and a t r a n s p o n d e r and r e c e i v e r on the RNS. ^ a'^tlii J'-^^ c*^ '^ f<| ^^'"^ « 111 112 '\^'' r
18120 GUIDANCE AND NAVIGATION CANDIDATES CONCEPT AUTONOMOUS NAV SATELLITES OR GROUND BEACONS GROUND TRACKING UNIQUE FEATURES LANDMARK TRACKER AND PROCESSING ® RANGING RADAR ® LUNAR ORBIT NAVIGATION AID ®TRANSPONDER ® MSFN 113
G U I D A N C E AND N A V I G A T I O N C H A R A C T E R I S T I C S T h e c h a r a c t e r i s t i c s of t h e t h r e e c a n d i d a t e s a r e s h o w n . G e n e r a l l y , t h e s y s t e m s a r e c o m p a r a b l e b e c a u s e of t h e l a r g e n u m b e r of c o m m o n itenns r e q u i r e d to d e t e r m i n e a t t i t u d e and s a t i s f y o t h e r m i s s i o n r e q u i r e m e n t s . T h e w e i g h t s of t h e t h r e e s y s t e m s a r e c o m p a r a b l e a s a r e t h e p o w e r r e q u i r e m e n t s . T h e funda,mental ^iffejr_en£e_s_arej.n Jhe__a£cura^ t r a c k i n g s.y.S-tem a n d t h e p r o c e s s i n g r e q u i r e m e n t s to p r o v i d e f o r a u t o n o m o u s n a v i g a t i o n . T h e i n a b i l i t y to d e t e r n n i n e t h e a v a i l a b i l i t y of t h e D S I F a n d t h e n i o d e s t i n c r e a s e in r e q u i r e m e n t s to p r o v i d e t o t a l l y a u t o n o m o u s n a v i g a t i o n s u g g e s t s t h e s e l e c t i o n of a n autonomous s y s t e m a s b a s e l i n e with a g r o u n d t r a c k i n g backup. Should the DSIF be a v a i l a b l e , it w o u l d be d e s i r a b l e to p r o v i d e for a n a c c u r a c y u p d a t e of t h e a u t o n o m o u s s y s t e m w i t h i n the p r o g r a m p l a n to t a k e a d v a n t a g e of t h e h i g h - a c c u r a c y c a p a b i l i t y of t h e g r o u n d t r a c k i n g s y s t e m . 114 t \
18121 GUIDANCE AND NAVIGATION CHARACTERISTICS PROCESSING CONCEPT ® AUTONOMOUS ® NAV 1 GAT ON ^ ^ SATELLIItS OR GROUND BEACONS ® GROUND TRACKING ACCURACY (FT) (EARTH ORBIT) WEIGHT (LB) POWER fW) RATE MEMORY 310 110 59.5K 13,7K 2,000 185 50K 1L4K 1,000 100 30K 4.4K 600 380 + ANTENNA 295 SELECTION -AUTONOMOUS WITH GROUND TRACKING BACKUP 115
GROUND COMMUNICATION Although n u m e r o u s data interfaces can be established between the RNS and other space p r o g r a m e l e m e n t s , the p r i m a r y r e c u r r i n g communication e x i s t s between the RNS command and control module and the ground. The baseline s y s t e m is r e p r e s e n t e d by using a d i r e c t link to ground stations located on E a r t h , with an a l t e r n a t e of commiunicating through a communications s a t e l l i t e . With r e l a t i v e l y low data r a t e s , a dump of data over each ground station can be effected. With v e r y high data r a t e s , communication satellites m u s t be used to e s t a b l i s h continual data flow to e a r t h . Th,ere is a strong d e s i r e to reduce the total quantity of data t r a n s m i t t e d to e a r t h without reducing the informational content of this data. Techniques of data c o m p r e s s i o n a r e well known to achieve this objective. Taking the total RNS data r e q u i r e m e n t , it can be d e t e r m i n e d that t h e r e is an expected 8, 800 s a m p l e s p e r second. F o r approximately ten bits per sanaple, 90, 000 bits per second of data would be g e n e r a t e d . Based on Gemini data c o m p r e s s i o n s i m u l a t i o n s , c o m p r e s sion r a t i o s of about 100 to 1 can be r e a l i z e d on the type of data anticipated for the RNS. This would reduce the total data t r a n s m i t t e d from orbit from 5 x 10^ bits per orbit to 5 x 10" bits per o r b i t . Assuming five ground stations would be a v a i l able and the total t r a n s m i s s i o n time over t h e s e ground stations w e r e 160 minutes per day, a t r a n s m i s s i o n r a t e to ground using data c o m p r e s s i o n would be 8. 5 x 10-^ bits p e r second. This low t r a n s m i s s i o n r a t e indicates that t h e r e is no r e q u i r e m e n t for communication satellite r e l a y to t r a n s m i t full information content to ground. Data c o m p r e s s i o n r e q u i r e m e n t s on the data management function r e p r e s e n t one of the l a r g e s t p r o c e s s i n g r e q u i r e m e n t s . However, it is c o n s i d e r e d totally within the capability of a conventional p r o c e s s o r . 116
18122 GROUND COIVIIVIUNICATION ---. ^ COMMUNICATION SATELLITE REQUIREMENTS ® 732 MEASUREMENTS ® 8800 SAMPLES/SEC COMPRESSED TELEMETRY / ® 90,000 BITS/SEC , GROUND COMMUNICATION WITH DATA COMPRESSION ® 5,1 X I O ^ BITS/ORBIT ® 8 . 5 X 1 0 ^ TRANSMISSION RATE DATA COMPRESSION PROCESSING REQUIREMENTS ©105,000 OPS/SEC 117
1 DATA MANAGEMENT PROCESSING AND STORAGE REQUIREMENTS The total p r o c e s s i n g and s t o r a g e r e q u i r e m e n t s for the data management function a r e s u m m a r i z e d in the facing c h a r t . F o r the data m a n a g e m e n t subsystenm, the bulk of the p r o c e s s i n g r e q u i r e m e n t s a r e derived from the executive r o u t i n e . Additionally, the p r o c e s s i n g r e q u i r e d to effect the p r o c e d u r e s s t o r e d on board a r e included. The guidance, navigation, and control p r o c e s s i n g r e q u i r e m e n t includes capability for totally autonomous navigation in addition to the n o r m a l guidance and attitude control functions. P r o v i s i o n is made for p r o c e s s i n g of ground uplink data that r e p r e s e n t s a backup to the nominal autonomous navigation s c h e m e . The i n s t r u m e n t a t i o n command and control r e q u i r e m e n t s has the data c o m p r e s s i o n r e q u i r e m e n t of 106, 000 operations p e r second a s its l a r g e s t e l e m e n t . The onboard checkout p r o c e s s i n g r e q u i r e m e n t is for peak operations only because m o s t of the checkout p r o c e d u r e s a r e p e r f o r m e d off peak. 118
18123 DATA fVIANAGEfVIENT PROCESSING AND STORAGE REQUIREMENTS STORAGE PROCESSING EQUIV ADD/SEC AT PEAK HIGH SPEED (WORDS) BULK (WORDS) DATA MANAGEMENT 40,000 3,700 25,000 GUIDANCE, NAVIGATION AND CONTROL (AUTONOMOUS) 83,200 16,000 15.400 109,800 6J50 6,000 8,200 1,200 24,350 241,200 27,650 70,750 INSTRUMENTATION, COMMAND AND CONTROL (INCLUDES DATA COMPRESSION) ONBOARD CHECKOUT SHARED CORE 1 i ' PROCSESSOR NO. 1 CORE i • ^ ^r BULK SViEMORY ^ i PROCIESSOR NO. 2 CORE i i I/O STRUCTURE Jlk. ARirk r t A T A oils? c;ONTROLLE R liSi If 119
DATA BUS C A N D I D A T E S F o u r r e p r e s e n t a t i v e concepts a r e indicated in the facing c h a r t . The four concepts p r e s e n t l y u n d e r d e v e l o p m e n t by v a r i o u s c o n t r a c t o r s a r e t i m e - s h a r e d s y s t e n n s u s i n g s e r i a l t r a n s n a i s s i o n on a c o a x i a l o r t w i s t e d s h i e l d e d p a i r l i n e and a l l u s e t r a n s f o r m e r c o u p l i n g of d a t a b u s t e r m i n a l s to the d a t a b u s l i n e s . T h e TRW c o n c e p t p r e s e n t l y b e i n g d e v e l o p e d (MDAC s p a c e s h u t t l e ) is c h a r a c t e r i z e d by two lines—one for a d d r e s s and d a t a and the o t h e r a c l o c k . H o r i z o n t a l and v e r t i c a l p a r i t y (word and b l o c k ) a r e i n c l u d e d . T h e n a t u r e of the TRW c o n c e p t i s t h a t only a d e v i c e - t o - c o n t r o l l e r t r a n s f e r is u s e d . T h e IBM c o n c e p t (MDAC s p a c e s t a t i o n ) is s i m i l a r but a l l o w s f o r d e v i c e - t o - d e v i c e t r a n s f e r s , h o w e v e r t h e r e is no a p p a r ent RNS r e q u i r e m e n t f o r t h i s c a p a b i l i t y . C u r r e n t m o d e t r a n s f o r n n e r c o u p l i n g and a polling c l o c k a r e u s e d , r e p r e s e n t i n g a d i f f e r e n c e fronn the o t h e r t h r e e c o n c e p t s . T h e c o n c e p t p r e s e n t l y u n d e r d e v e l o p n n e n t at N A S A / M S F C i n c l u d e s a t w o - l i n e approach—one w i t h d a t a and the o t h e r w i t h a d d r e s s , comimand, and t h e c l o c k i n t e g r a t e d . W o r d p a r i t y i s u s e d w i t h one b i t f o r e a c h p o l a r i t y on f i l t e r e d b i p o l a r d a t a . T h e r a d i a t i o n c o n c e p t u s e s a s i n g l e line w i t h t o t a l i n f o r m a t i o n c o n t e n t . T r i p l e l i n e r e d u n d a n c y i s u s e d and c r e d i b i l i t y t e s t i n g done at e a c h d a t a bus t e r m i n a l . 120
18124 DATA BUS CANDIDATES CONCEPT LINE FUNCTION BIT RATE CODING SELF CHECK TRW 1 DATA/ADDRESS 1 CLOCK IMHZ MANCHESTER WORD + BLOCK PARITY IBM IDATA 1 POLLING CLOCK 2 MHz BIPOLAR ADDRESS + WORD PARITY NASA/MSFC IDATA 1 ADDRESS/ COMMAND/CLOCK 2 MHz BIPOLAR WORD PARITY FOR EACH POLARITY RAD ATiON 1 FULL SERVICE TRIPLY REDUNDANT 5 MHz MANCHESTER WORD PARITY 121
DATA BUS ARCHITECTURE The data bus a r c h i t e c t u r e for the C l a s s 1 H and C l a s s 3 RNS is indicated. The m a x i m u m traffic r a t e anticipated for an operational vehicle is about 1/4 x 10° bits per second. The m a x i m u m load is derived p r i m a r i l y from the t r a n s m i s s i o n of data from all modules to the data bus c o n t r o l l e r before the c o m p r e s s i o n o p e r ation. The number of data bus t e r m i n a l s includes one data bus in each propellant module for the C l a s s 3 and one data bus t e r m i n a l fore and aft of the C l a s s 1 Hybrid tankage. The p r o c e s s i n g r e q u i r e m e n t s for the data bus a r e quantified and a s s u m e s the controller function is p e r f o r m e d by the data management s u b s y s t e m . A l t e r nately, a p r o c e s s i n g capability can be provided within the data bus c o n t r o l l e r . An independent NDICE is a s s u m e d that will u s e the RNS data b u s . Typical supporting h a r d w a r e used in each module for the generation of commands and the collection and digitizing of module data a r e shown. 122
18112 DATA BUS ARCHITECTURE CCM DATA BUS CONTROLLER NDICE DBT I MAX TRAFFIC RATE ON BUS • CCM DBT'S DEVELOPMENT-0.5X # • OPERATIONAL-0.23X # CMD DECODE DATA BUS TERMINAL ADC twux SIG COND INSTR NO. OF DATA BUS TERMINALS EACH PROPELLANT MODULE CLASS 1 — 8 REQUIRED CLASS 3 - - 1 4 REQUIRED PROCESSING REQUIREMENT 9,000 OPS/SEC 500 WORDS STORAGE 123 BITS/SEC BITS/SEC
N, RNS DESIGN SUMMARY C u r r e n t RNS designs will be briefly s u m m a r i z e d in this section starting with sketches of the two concepts, the Class 1 Hybrid and Class 3. The m a j o r design features which w e r e selected during the second period will be identified on s u b sequent c h a r t s . Finally, the weights for both concepts will be given. 124
RNS DESIGN SUMMARY • RNS SCHEMATICS CLASS 1 HYBRID CLASS 3 • DESIGN FEATURES SELECTED DURING SECOND PERIOD #CURRENT WEIGHT STATEMENTS
RNS CLASS 1 HYBRID A sketch of the Class 1 Hybrid RNS configuration is shovi^n on the facing c h a r t . It i l l u s t r a t e s the c u r r e n t configuration and p r o v i d e s a locator for the specific features selected during the second period of the study which will be d i s c u s s e d on subsequent c h a r t s . The t h r e e distinct modules a r e visible as well as t h e i r containment within the 10degree half-angle cone m e a s u r e d from the NERVA engine which was selected during the P h a s e II shield optimization. The o u t r i g g e r s containing the auxiliary propulsion engines on the command and control modules a r e also visible on the p i c t u r e . Specific details a r e identified by the c a l l o u t s . 126
CLASS 1 HYBRID RNS COMAAAND & CONTROL MODULE FORWARD UMBILICALSLOSH BAFFLE INTEGRAL WAFFLETUNNELINTER-IVIODULE STRUCTURE DOCKING INTERFACE LIQUID LEVEL SENSORS APS NOZZLESPRAY NOZZLE REFILL PROPELLANTMODULE PROPELLANT ^—THERfVIAL/fVlETEOROID PROTECTION FEED SYSTEM •PROPULSION MODULE NERVA 127
RNS CLASS 3 This c h a r t shows the c u r r e n t baseline configuration for the Class 3 RNS concept. Clustering of outboard propellant modules into a c r u c i f o r m configuration at the second propellant module level is i l l u s t r a t e d . C o m p a r i s o n with the previous sketch shows how both RNS concepts have converged in t h e i r c h a r a c t e r i s t i c s by definition of the functional m o d u l e s . It can be seen that the only basic difference between the two concepts is the m a n n e r in which propellant is stored—within the multiple modules in this c a s e and in the single propellant module for the C l a s s 1 Hyb rid. The main feed s y s t e m , providing communication frora any propellant module to the run tank on the propulsion module, is shown in this figure. Other details a r e noted by the callouts. Again, this sketch should be used as a locator for the d i s c u s s i o n of the design f e a t u r e s selected during this period. 128
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18115 DESIGN FEATURES SELECTED • HEMISPHERICAL FORWARD DOME-CLASS 1 PROPELLANT MODULE • INTEGRAL WAFFLE PATTERN-CLASS 3 PROPELLANT MODULE • 160 INCH RUN TANK DIAMETER-CLASS 3 PROPULSION MODULE • FIBERGLASS COMPOSITE STRUCTURE-REVIEWED • AUTONOMOUS NAVIGATION • CENTRALIZED DATA PROCESSING • STORED PROCEDURES FOR ONBOARD CHECKOUT ® BITE FOR SPECIFIC COMPONENTS 131
DESIGN FEATURES SELECTED ~ 2 Additional c h a r a c t e r i s t i c s for RNS s u b s y s t e m s which w e r e selected during the second period a r e shown on the facing c h a r t . The integrated chilldown subsystemi which combines the NERVA and stage chilldown operations as well as including the operations a s s o c i a t e d with refill or the run tank following depletion was d e s c r i b e d e a r l i e r . Additionally, a blocking valve was added in the C l a s s 3 feed s y s t e m s connecting the v a r i o u s propellant module tanks into the run tank. This enhances feed s y s t e m integrity as well as eliminating e x c e s s i v e liquid r e s i d u a l s following shutdown and e x c e s s i v e t h e r m a l l e a k s . The auxiliary propulsion s y s t e m was sized for both concepts. A engine t h r u s t was selected based upon p e r f o r m i n g r e q u i s i t e m a n e u v e r s , attitude control, and propellant settling. Total propellant capacity was e s t a b l i s h e d for the baseline lunar shuttle m i s s i o n . The p r i m a r y power s o u r c e t r a d e study p e r f o r m e d during P h a s e II was reviewed in t e r m s of c u r r e n t power r e q u i r e m e n t s . The final selection was inade bet'ween fuel cells and s o l a r cells utilizing s t a t e - o f - t h e - a r t projections for fuel cells which a r e being employed in the space shuttle, and for solar cells which a r e to be employed in advanced space p r o g r a m s beyond Skylab. The evaluation favored fuel cells for the RNS. Redundant fuel c e l l s a r e provided for r e l i a b i l i t y . 132
18116 DESIGN FEATURES SELECTED - 2 #INTEGRATED CHILLDOWN SUBSYSTEM ® COMBINED NERVA/STAGE CHILLDOWN ® INCLUDES REFILL OF RUN TANK # BLOCKING VALVE IN FEED SUBSYSTEM-CLASS 3 # AUXILIARY PROPULSION SYSTEM SIZED ® ENGINE THRUST ® PROPELLANT CAPACITY # REDUNDANT FUEL CELLS-PRIMARY POWER-REVIEWED 133
RNS WEIGHT STATEMENT The accompanying c h a r t contains c u r r e n t weight s t a t e m e n t s for both RNS concepts. F o r n e a r l y identical propellant capacities it can be seen that both the s t r u c t u r e , m e t e r o i d / t h e r m a l , and d o c k i n g / c l u s t e r i n g e n t r i e s penalize the nnultiple-module C l a s s 3 concept. The main propulsion e n t r y contains a 2, 800-lb biological shield for the C l a s s 1 Hybrid concept which a l m o s t offsets the g r e a t e r plumbing and component weights for the C l a s s 3 concept. The l a s t t h r e e e n t r i e s under the d r y weight a r e n e a r l y the s a m e for both concepts. A net d r y weight advantage of n e a r l y 10, 000 lb a c c r u e s to the C l a s s 1 concept. It can be seen that the RCS propellant is n e a r l y identical for both concepts, but that the r e s i d u a l s of propellant contained in the stage at burnout a r e about 75, 000 lb heavier for the C l a s s 1 concept than for C l a s s 3. This r e s u l t s in a net difference in operational weight of only about 2, 000 lb favoring C l a s s 1. These g r e a t e r r e s i d u a l s for the C l a s s 1 concept diminish the usable propellant so that the propellant m a s s fraction, \ ' , given as the l a s t e n t r y is identical for both configurations. 134
18117 RNS WEIGHT STATEMENT CLASS 1 HYBRID CLASS 3 ILB) (LB) STRUCTURE ME IEORO ID/THERMAL DOCKING/CLUSTERING MAIN PROPULSION AUXILIARY PROPULSION ASTRIONICS CONTINGENCY 24,080 7,910 760 31,220 1,010 2,135 1,840 28,750 8,800 3,440 31,840 1,010 2,430 2,410 TOTAL DRY WEIGHT 68,955 78,680 RCS PROPELLANT PROPELLANT RESIDUALS 1,130 9,470 1,140 1,920 79,555 81,740 1,700 289,830 2,240 1,700 297,190 0.784 0J84 TOTAL OPERATIONAL WEIGHT VENTED PROPELLANT FLIGHT PERFORMANCE RESERVE USABLE PROPELLANT PROPELLANT MASS FRACTION, A'
TEST DEFINITION APPROACH The t e s t r e q u i r e m e n t s t a s k is in p r o g r e s s with a bottom-up approach employing t e s t item and s y s t e m test candidate w o r k s h e e t s . E a c h t e s t item is examiined in the t e s t item worksheet to d e t e r m i n e the amount and type of t e s t s that should be p e r formed to provide the n e c e s s a r y design data, to verify the design approach, and to qualify the item for use in the RNS. Data a r e p r e s e n t e d on the t e s t itenn w o r k s h e e t on the specific connponents on the RNS included in the t e s t item, the maintenance category of the component, the r e l i a b i l i t y allocation, the confidence level, and the lifetime r e q u i r e m e n t s . These data a r e used to d e t e r m i n e the amount of testing to be accomplished. The type of testing is d e t e r m i n e d by examining the function of the component and the operational environment. This leads to a listing of the specific t e s t s that a r e r e q u i r e d in the r e s e a r c h and development, development, qualification, and acceptance testing a r e a s . T e s t s in the component, s u b s y s t e m , and s y s t e m levels a r e delineated along with a l t e r n a t i v e s for the specified t e s t s . The data from the t e s t item w o r k s h e e t a r e used in the System T e s t Worksheets w h e r e all candidate t e s t s above the component level a r e examined to d e t e r m i n e the optimum t e s t s t r a t e g y . Specific topics covered a r e a d e s c r i p t i o n of the proposed test, why it is r e q u i r e d , the worth of the t e s t , the a l t e r n a t i v e s , and the h a r d w a r e and facility r e q u i r e m e n t s along with the cost and schedule i m p l i c a t i o n s . The r e s u l t s of these analyses a r e then fused into an o v e r a l l integrated t e s t plan, which will provide the b a s i s for t e s t h a r d w a r e and ground support equipment definition. The integrated t e s t plan formulation, as well a s definition of the t e s t h a r d w a r e and ground support equipment, will be accomplished during J a n u a r y and early February. 136
18080 TEST DEFINITION APPROACH TEST ITEM WORKSHEETS # COMPONENT IDENTIFICATION & CHARACTERISTICS (NO. COMPONENTS, MAINT CATEGORY, REL ALLOC, ETC) ® TEST REQUIREMENTS (RES &TECHNOL, DEV, QUAL, & REL TESTING) SYSTEM TEST WORKSHEETS # CANDIDATE SYSTEM TESTS ARE SUBJECTED TO THE FOLLOWING QUESTIONS: « WHAT DOES THE TEST DO? « WHY IS THE TEST REQUIRED? « WHAT ARE THE FACILITY/HARDWARE REQUIREMENTS? ^ WHAT IS THE ESTIMATED WORTH OF THE TEST? - WHAT ARE THE ALTERNATIVES TO BE CONSIDERED? « WHAT IS THE IMPACT OF ALTERNATIVES ON COST & SCHEDULES? •WHAT IS THE FINAL DECISION REGARDING THIS SYSTEM TEST? 137
SYSTEMS INTEGRATION LABORATORY (SIL) The Systems Integration L a b o r a t o r y , which was successfully employed on the S-IVB p r o g r a m , is r e q u i r e d to provide the opportunity to verify that the e l e c t r i c a l interfaces between the components, s u b s y s t e m s , m o d u l e s , NDICE, and the g r o u n d / a e r o s p a c e support equipment is adequate to m e e t the s y s t e m r e q u i r e m e n t s or to d e t e r m i n e that interface p r o b l e m s exist; it is also r e q u i r e d to provide the design information r e q u i r e d for component, s u b s y s t e m , module, NDICE, or support equipment r e d e s i g n . This t e s t is also n e c e s s a r y to develop the onboard and ground automatic checkout s y s t e m software p r o c e d u r e s . The SIL t e s t s will investigate the e l e c t r i c a l i n t e r f a c e s under n o r m a l and extended p a r a m e t e r operation. The h a r d w a r e to be involved should include all e l e c t r i c a l components ranging from the p r i m a r y e l e c t r i c a l source (fuel cells and b a t t e r i e s ) through the interconnections (cables and disconnects) to the final component (valves, m o t o r s , e t c . ), and including the control s y s t e m ( c o m p u t e r s , m u l t i p l e x e r s , etc, ). The data from this t e s t should provide a c c u r a t e information on the e l e c t r i c a l interfaces under ambient environmental conditions and n o r m a l and abnormal o p e r a t i o n s . These data should r e v e a l any p r o b l e m a r e a s or verify conformity with RNS r e q u i r e m e n t s . The data should also provide design information useful or r e q u i r e d in the r e d e s i g n of the components or s u b s y s t e m . Additionally, the t e s t should provide information useful or r e q u i r e d in the design of the onboard and ground support checkout s y s t e m s . 138
18081 SYSTEMS INTEGRATION LABORATORY PURPOSE ©INVESTIGATE, VERIFY, PROVIDE DESIGN INFORMATION FOR ELECTRICAL/MECHANICAL INTERFACE & SYSTEM OPERATION # DEVELOP CHECKOUT OPERATIONS & SOFTWARE TESTS # MECHANICAL - CONNECTOR COVIPATIBILITY # ELECTRICAL - VOLTAGE, CURRENT, ETC # OPERATIONAL - TIMING, RESPOMSE, ETC # ABNORMAL OPERATIONS - LOW VOLTAGE, HIGH IMPEDANCE, ETC # CHECKOUT DEVELOPMENT - FAILURE ISOLATION, TREND DATA, ETC HARDWARE # ALL ELECTRICAL COMPONENTS TEST LEVEL # SUBSYSTEM, SYSTEM, MODULE, RNS 139
PROPULSION INTEGRATION LABORATORY (PIL) T h e P r o p u l s i o n I n t e g r a t i o n L a b o r a t o r y ( P I L ) i s an a c t i v e e l e c t r i c a l , m e c h a n i c a l , and fluid m o c k u p of t h e p r o p u l s i o n s u b s y s t e m s . T h e t e s t w i l l i n v e s t i g a t e and d e v e l o p t h e m e c h a n i c a l and fluid i n t e r f a c e s b e t w e e n p r o p u l s i o n s y s t e m c o m p o n e n t s , b e t w e e n m o d u l e s of t h e RNS and b e t w e e n t h e RNS and t h e N E R V A . T h e t e s t s w i l l i n v e s t i g a t e t h e fluid c o n d i t i o n s a n d p e r f o r m a n c e of t h e p r o p u l s i o n s y s t e m u n d e r n o r n n a l a n d a b n o r m a l c o n d i t i o n s . T h e m e c h a n i c a l a n d fluid i n t e r f a c e s m u s t be v e r i f i e d and d e s i g n i n f o r m a t i o n o b t a i n e d f o r u s e in t h e r e d e s i g n effort. T h e p e r f o r m a n c e of t h e p r o p u l s i o n s y s t e m a s a unit m u s t be v e r i f i e d p r i o r to t h e t i m e t h a t t h e s y s t e m is s u b j e c t e d to h i g h e r l e v e l t e s t i n g o r t h e d e s i g n i s c o n s i d e r e d t o b e a d e q u a t e and f u r t h e r d e s i g n i s t e r m i n a t e d . T h e d a t a f r o m t h i s t e s t should p r o v i d e a c c u r a t e i n f o r m a t i o n on t h e m e c h a n i c a l i n t e r f a c e s u n d e r a m b i e n t a n d c r y o g e n i c c o n d i t i o n s and n o r m a l and a b n o r m a l o p e r a t i o n s . T h e d a t a on t h e p e r f o r m a n c e of t h e system—flow d y n a m i c s , c h i l l d o w n , e t c . m u s t be a d j u s t e d t o a c c o u n t f o r t h e l a c k of s p a c e c o n d i t i o n s — z e r o g r a v i t y , s p a c e t e m p e r a t u r e s , v a c u u m , e t c . Hov^^ever, t h e d a t a w i l l b e i n v a l u a b l e i n t h e d e s i g n a n d a n a l y s i s p r o c e s s a s a n e x p e r i m e n t a l v e r i f i c a t i o n of t h e a n a l y t i c a l t e c h n i q u e s u s e d in t h e p e r f o r m a n c e a n a l y s i s and d e s i g n . The l e v e l of t h e t e s t c h o s e n w i l l be t h e s u b j e c t of a n e c o n o m i c s / t e s t r e s u l t t r a d e off. T h e l e v e l c o u l d c o n s i s t of a c o l l e c t i o n of s u b s y s t e m s (vent, p r e s s u r i z a t i o n , e t c . ), t h e e n t i r e p r o p u l s i o n s y s t e m of a s i n g l e m o d u l e , t h e p r o p u l s i o n s y s t e m of s e v e r a l m o d u l e s , o r t h e p r o p u l s i o n s y s t e m of one o r s e v e r a l m o d u l e s w i t h a NERVA simulator. 140
PROPULSION INTEGRATION LABORATORY PURPOSE #INVESTIGATE, VERIFY, PROVIDE DESIGN INFORMATION FOR MECHANICAL & FLUID INTERFACE & SYSTEM OPERATION TESTS #MECHANICAL INTERFACE ^DIMENSIONAL AMBIENT CRYOGENIC # SYSTEM OPERATION ^CHILLDOWN, PRE-PRESS, VENTING, COOLDOWN «LH2 TRANSFER - BETWEEN MODULES & INFLIGHT ^CHECKOUT OPERATIONS - LEAK DETECTION HARDWARE #ALL PROPULSION SYSTEM COMPONENTS TEST LEVEL #SUBSYSTEM, SYSTEM, SINGLE MODULE, MULTIPLE MODULE 141
S P E C I A L DOCKING S I M U L A T O R T h i s t e s t is an a c t i v e m o c k u p of t h e d o c k i n g and d i s c o n n e c t c o m p o n e n t s of t h e R N S . It w i l l i n v e s t i g a t e and d e v e l o p t h e s t a t i c and d y n a m i c m e c h a n i c a l , e l e c t r i c a l , and o p t i c a l / l a s e r o p e r a t i o n a n d i n t e r f a c e s of t h e v a r i o u s d o c k i n g m e c h a n i s m s and d i s c o n n e c t s b e t w e e n t h e m o d u l e s of t h e RNS, b e t w e e n t h e RNS and t h e p a y l o a d , and b e t w e e n t h e RNS a n d o t h e r s p a c e f a c i l i t i e s u n d e r n o r m a l and a b n o r m a l c o n d i t i o n s . T h e t e s t i s r e q u i r e d to v e r i f y and p r o v i d e r e d e s i g n i n f o r m a t i o n on t h e a b i l i t y of t h e d o c k i n g m e c h a n i s m s a n d t h e d i s c o n n e c t s to w i t h s t a n d t h e s t a t i c and d y n a m i c l o a d i n g s d u r i n g t h e d o c k i n g o p e r a t i o n a n d t h e r e m a i n d e r of t h e RNS o p e r a t i n g c y c l e u n d e r n o r m a l a n d a b n o r m a l c o n d i t i o n s . In a d d i t i o n , s i m p l e d i m e n s i o n a l compatibility verification is required. T h e l e v e l of t e s t i n g c o u l d v a r y f r o m a s i m p l e t e s t r i g t h a t would s i n a u l a t e t h e d o c k ing o p e r a t i o n s and l o a d i n g s on s i n g l e p a i r s of d o c k i n g and d i s c o n n e c t m e c h a n i s n n s to a t e s t r i g t h a t would s i m u l a t e t h e m o d u l e s w i t h m a s s and e n v e l o p e m o c k u p s , in a d d i t i o n t o c o m p l e t e s e t s of d o c k i n g a n d d i s c o n n e c t m e c h a n i s m s . T h e l e v e l of t e s t c o u l d a l s o b e an a c t u a l d o c k i n g o p e r a t i o n b e t w e e n a c t u a l m o d u l e s . T h e l a t t e r t e s t l e v e l -would p r o v i d e i n f o r m a t i o n on t h e e f f e c t s of t h e d o c k i n g o p e r a t i o n on a l l m o d u l e c o m p o n e n t s , in a d d i t i o n t o t h e a c t u a l d o c k i n g and d i s c o n n e c t m e c h a n i s m s . 142
SPECIAL DOCKING SIMULATOR PURPOSE # INVESTIGATE, VERIFY, PROVIDE DESIGN INFORMATION FOR MECHANICAL & ELECTRONIC DOCKING SYSTEM TESTS # MECHANICAL INTERFACE DIMENSIONAL- STATIC TESTS # DYNAMIC INTERFACE DOCKING SIMULATIONS DISCONNECT OPERATION # OPERATIONAL AXIAL LOAD, SHEAR, BENDING MOMENT, ETC HARDWARE # ALL DOCKING MECHANISMS, DISCONNECTS TEST LEVEL # SUBSYSTEM, SUBSYSTEM WITH MASS SIMULATOR, MODULE 143
BATTLESHIP TEST PROGRAM The b a t t l e s h i p t e s t is r e q u i r e d to p r o v i d e t i m e l y d a t a on t h e a d e q u a c y of t h e d e s i g n and timiely r e d e s i g n i n f o r m a t i o n . T h e s e d a t a c a n n o t b e o b t a i n e d a t t h e c o m p o n e n t o r s u b s y s t e m l e v e l due to t h e a b s e n c e of t h e m a n y i n t e r f a c e s . F o r e x a m p l e , t h e t e s t i n g of a v a l v e d o e s n o t t e s t t h e d u c t i n g t h a t c o n n e c t s the v a l v e s o r t h e c o n n e c t i o n s t h e m s e l v e s — t h e e n t i r e s u b s y s t e m o r systemi m u s t b e t e s t e d a s a unit to i n v e s t i g a t e t h e a b i l i t y of the s y s t e m ( v a l v e s , d u c t i n g and c o n n e c t i o n s ) to w i t h s t a n d t h e r e q u i r e d p r e s s u r e a n d p r e s s u r e t r a n s i e n t s , t e m i p e r a t u r e and t e m p e r a t u r e t r a n s i e n t s , flow r a t e and flow r a t e t r a n s i e n t s , and t h e effect t h a t e a c h of t h e i n d i v i d u a l c o m p o n e n t s ( v a l v e s , d u c t i n g , and c o n n e c t i o n s ) h a s on t h e p r e s s u r e , p r e s s u r e t r a n s i e n t s , t e m p e r a t u r e , t e m p e r a t u r e t r a n s i e n t s , flow r a t e and flow r a t e t r a n s i e n t s of a l l of t h e o t h e r c o m p o n e n t s . A s u b s y s t e n a - l e v e l t e s t ( P r o p u l s i o n I n t e g r a t i o n L a b o r a t o r y ) w i l l p r o v i d e a g r e a t d e a l of t h i s i n f o r m a t i o n and is a n e c e s s a r y s t e p in t h e e v o l u t i o n of t h e t e s t s e q u e n c e , b u t a s u b s y s t e m t e s t will not p r o v i d e a l l of t h e r e q u i r e d i n f o r m a t i o n . F o r e x a m p l e , t e s t i n g t h e p r o p u l s i o n m o d u l e feed s y s t e n a in t h e P I L w i l l t e s t t h e feed v a l v e s and d u c t i n g but w i l l not t e s t the p r o p u l s i o n m o d u l e t a n k , t h e c o n n e c t i o n s b e t w e e n t h e fill s y s t e m and t h e p r o p u l s i o n m o d u l e t a n k , o r t h e effect of t h e p r e s s u r i z a t i o n and v e n t s y s t e m on t h e o p e r a t i o n of t h e fill s y s t e m . A l s o , it w i l l t e s t t h e effect of t h e p r o p e l l a n t m o d u l e p r o p e l l a n t t a n k , t h e p r o p e l l a n t m o d u l e feed s y s t e m , v e n t systenn. and p r e s s u r i z a t i o n s y s t e m on t h e o p e r a t i o n of the p r o p u l s i o n m o d u l e fill s y s t e m ; the effect of t h e N E R V A and t h e e n v i r o n m e n t it c r e a t e s on t h e p r o p u l s i o n nnodule fill s y s t e m ; and the t h e o r y t h a t t h e p r o p u l s i o n m o d u l e fill s y s t e m i s i n d e p e n d e n t of t h e o p e r a t i o n of t h e s e s y s t e m s . A l l of t h e s e e f f e c t s m u s t b e a n a l y z e d u n d e r n o r m a l and a b n o r m a l c o n d i t i o n s . The b a t t l e s h i p tank and specific s a f e t y / e m e r g e n c y s y s t e m s will be r e q u i r e d to a l l o w e x t e n d e d p a r a m e t e r t e s t i n g (high and low p r e s s u r e , h i g h and low p r e s s u r e r a t e s , h i g h and low t e m p e r a t u r e , e t c . ). T h i s c o n d i t i o n would be difficult if not i m p o s s i b l e w i t h o u t a s p e c i a l (nonflight) t a n k w i t h t h i c k e r w a l l s and e x t r a p e n e t r a t i o n s . T h e r e f o r e , t h e r e q u i r e d i n f o r m a t i o n t h a t c o u l d n o t b e o b t a i n e d on an a l l s y s t e m s t e s t a r t i c l e could be o b t a i n e d a t a n e a r l y d a t e (1 to 2 y e a r s b e f o r e flight) s u f f i c i e n t to a l l o w c o m p o n e n t , s u b s y s t e m , o r s y s t e n a r e d e s i g n p r i o r to f i r s t flight. 144
BATTLESHIP TEST PROGRAM PURPOSE ® INVESTIGATE, VERIFY, PROVIDE DESIGN INFORMATION ON ENTIRE SYSTEM INTERFACES & OPERATION # VERIFY CHECKOUT OPERATION # PROVIDE GTM FOR NERVA TESTS # INTEGRATION OF ALL SYSTEMS m OPERATION OF SYSTEMS WITH PROPELLANT TANKS FILL, PRESSURIZATION, FEED. VENT, CHILLDOWN # OPERATION OF SYSTEM WITH NERVA PRESSURIZATION, PREPRESSURIZATiON, FEED, CHILLDOWN # AB NORMAL OPERATIONS HIGH PRESSURE, HIGH FLOW RATE, HIGH IMPEDANCE 145
MANUFACTURING PROGRAM T h e m a n u f a c t u r i n g e f f o r t s for t h e P h a s e III s t u d y i n v o l v e t h e f o r m u l a t i o n of n a a n u f a c t u r i n g p l a n s for b o t h C l a s s 1 h y b r i d a n d C l a s s 3 RNS c o n c e p t s , w i t h e a c h m a n u f a c t u r i n g p l a n to i n c l u d e t h e d e f i n i t i o n of m a n u f a c t u r i n g a n d a s s e m i b l y t e c h n i q u e s , a s w e l l a s e s t i m a t e s of t o o l i n g a n d f a c i l i t i e s r e q u i r e n a e n t s . T h e u s e of a d v a n c e d m a n u f a c t u r i n g c o n c e p t s , s u c h a s l a r g e s h e e t s i z e s to m i n i m i z e n u m b e r s of p a r t s and o p e r a t i o n s , s i n g l e p i e c e d o m e s , and e l e c t r o n b e a m w e l d i n g a r e b e i n g c o n s i d e r e d , w h e r e p r a c t i c a l , f o r e a c h RNS c o n c e p t . L a r g e s h e e t s t o c k (210 in. w i d e by 1,440 i n . long) is c u r r e n t l y p r o j e c t e d f o r 1971 a v a i l a b i l i t y . T h e s e s i z e s p e r m i t t h e m a n u f a c t u r e of t a n k s w i t h c o n s i d e r a b l y f e w e r e l e n a e n t s t h a n would be r e q u i r e d u s i n g c o n v e n t i o n a l m a t e r i a l s i z e s (120 in. w i d e by a p p r o x i n a a t e l y 1, 000 in. l o n g ) . T h e c y l i n d r i c a l and t r u n c a t e d s e c t i o n s of t h e Class 1 hybrid propellant module could be m a d e from six longitudinal s e g m e n t s e a c h , w h e r e a s c o n v e n t i o n a l t e c h n i q u e s ( c y l i n d r i c a l c o u r s e s ) and s h e e t s i z e s w o u l d r e q u i r e a t l e a s t t e n e l e m e n t s for t h e c y l i n d e r and a p p r o x i m a t e l y e i g h t e l e m e n t s f o r the t r u n c a t e d s e c t i o n s . L a r g e s h e e t u t i l i z a t i o n , c o m b i n e d w i t h s i n g l e p i e c e d o m e s , p r o v i d e s a t e c h n i q u e for m a k i n g C l a s s 3 p r o p e l l a n t m o d u l e t a n k a g e with only five s t r u c t u r a l e l e m e n t s , t h u s r e d u c i n g t h e a m o u n t of w e l d l e n g t h s and o p e r a t i o n s , such a s fit-up, as well a s the software, e . g . , planning p a p e r , that is a s s o c i a t e d with t h e p r o d u c t i o n p r o g r a n a . E l e c t r o n b e a m w e l d i n g is c u r r e n t l y c o n s i d e r e d a s a s t r o n g c a n d i d a t e f o r t h e m a n u f a c t u r e of the C l a s s 3 p r o p e l l a n t m o d u l e s , a s w e l l a s t h e p r o p u l s i o n m o d u l e and c o m m a n d a n d c o n t r o l naodule f o r b o t h c o n c e p t s , s i n c e t h e 15-ft d i a n a e t e r i s nauch m o r e c o m p a t i b l e with t h e c l o s e t o l e r a n c e f i t - u p r e q u i r e m e n t s a s s o c i a t e d with e l e c t r o n b e a m w e l d i n g t h a n t h e 33-ft d i a m e t e r . T e c h n i q u e s s u c h a s p u l s e d a r c MIG o r TIG a r e t h e c u r r e n t p r i m a r y c o n t e n d e r s f o r w e l d i n g t h e 33-ft dianaeter propellant module. A t o t a l of e i g h t c a n d i d a t e m a n u f a c t u r i n g p r o g r a m s c e n a r i o s a r e b e i n g e v a l u a t e d a s p a r t of t h i s t a s k . F o r t h e C l a s s 1 h y b r i d , five p r o g r a m s a r e a s f o l l o w s : (1) p r o p e l l a n t m o d u l e a t M i c h o u d , p r o p u l s i o n m o d u l e and c o m m a n d a n d c o n t r o l m o d u l e at H u n t i n g t o n B e a c h , (2) a l l m o d u l e s a t M i c h o u d , (3) p r o p e l l a n t m o d u l e a t S e a l B e a c h , p r o p u l s i o n m o d u l e and c o m n a a n d a n d c o n t r o l m o d u l e at H u n t i n g t o n B e a c h , (4) a l l m o d u l e s a t S e a l B e a c h , and (5) a l l m o d u l e s a t H u n t i n g t o n B e a c h . F o r t h e C l a s s 3 RNS, t h e t h r e e c a n d i d a t e p r o g r a m s a r e : (1) a l l m o d u l e s a t M i c h o u d , (2) a l l m o d u l e s a t S e a l B e a c h , a n d (3) a l l m o d u l e s a t H u n t i n g t o n B e a c h . T h e c u r r e n t b a s e l i n e p r o g r a m s s e l e c t e d f r o m t h e s e c a n d i d a t e s a r e shown h e r e . 146
18106 MANUFACTURING PROGRAM APPROACH ® INTRODUCE ADVANCED CONCEPTS WHERE APPLICABLE TO REDUCE NUMBER OF OPERATIONS AND IMPROVE QUALITY OF FINISHED PRODUCT ® LARGE SHEET SIZES ® UNIQUE FORMING METHODS ® ADVANCED WELDING TECHNIQUES ® FORMULATE MANUFACTURING PLANS BASED ON MAXIMUM USE OF EXISTING FACILITIES SIGNIFICANT RESULTS # LARGE SHEET STOCK USED FOR CLASS-1 HYBRID PROPELLANT-MODULE CYLINDER (6 SEGMENTS) AND CLASS-3 PROPELLANT-MODULE CYLINDER 6 SEGMENTS) # SINGLE PIECE FORGED DOMES USED EXCLUSIVELY FOR CLASS--3, AND FOR AFT DOME OF CLASS-1 HYBRID PROPELLANT-MODULE # ELECTRON BEAM WELDING OF CLASS-3 MODULES CONSIDERED AS STRONG CANDIDATE # CURRENT CLASS-1 HYBRID MANUFACTURING PROGRAM BASELINE FEATURES PROPELLANT MODULE FINAL ASSEMBLY AT MICHOUD, PROPULSION MODULE AND COMMAND AND CONTROL MODULE AT MDAC-HUNTINGTON BEACH # CURRENT CLASS-3 MANUFACTURING PROGRAM BASELINE FEATURES MANUFACTURE OF ALL MODULES AT MDAC-HUNTINGTON BEACH 147
FACILITIES DEFINITION T h e f a c i l i t i e s a c t i v i t y is b e i n g c o n d u c t e d in t h r e e s u b t a s k s : n a m e l y , f a c i l i t i e s r e q u i r e n a e n t s , facilities utilization study, and facilities plan. C u r r e n t efforts h a v e f o c u s e d on t h e d e f i n i t i o n of m a n u f a c t u r i n g , t e s t i n g , and l a u n c h f a c i l i t y r e q u i r e m e n t s , and t h e i n v e s t i g a t i o n of t h e c o m p a t i b i l i t y of c u r r e n t l y e x i s t i n g f a c i l i t i e s with t h e r e q u i r e m e n t s d e f i n e d . T h e f a c i l i t i e s p l a n w i l l be f o r m u l a t e d d u r i n g t h e t h i r d p h a s e of t h e s t u d y . F o r b o t h c o n c e p t s e x i s t i n g f a c i l i t i e s c a n b e u t i l i z e d w i t h no m a j o r m o d i f i c a t i o n s . The C l a s s 1 hybrid propellant module can be manufactured at either Michoud or S e a l B e a c h w i t h o u t c o s t l y m o d i f i c a t i o n s to n o n s e v e r a b l e f a c i l i t i e s . At M i c h o u d , w h i c h is the b a s e l i n e final a s s e m b l y l o c a t i o n for t h e C l a s s 1 p r o p e l l a n t m o d u l e , a p p r o x i m a t e l y 123, 000 s q u a r e f e e t of f l o o r s p a c e w i l l be r e q u i r e d in B u i l d i n g 103 ( h o r i z o n t a l p o s i t i o n Avork) a n d B u i l d i n g 110 ( v e r t i c a l a s s e m b l y and h y d r o s t a t i c t e s t i n g ) . T h e C l a s s 3 RNS c a n b e m a n u f a c t u r e d in t o t a l a t MDAC—Huntington B e a c h f a c i l i t i e s w i t h no m a j o r m o d i f i c a t i o n s o r a d d i t i o n s r e q u i r e d . T h e d e t a i l f a b r i c a t i o n a n d final a s s e m b l y w o u l d be a c c o m p l i s h e d in B u i l d i n g 49, w i t h h y d r o s t a t i c t e s t i n g in B u i l d i n g 4 2 . T h e i m p a c t of e i t h e r RNS c o n c e p t on KSC f a c i l i t i e s w i l l b e m i n i m a l , a s n o t e d . T h e low b a y a r e a s r e q u i r e d w o u l d n o t h a v e to b e c h e c k o u t c e l l s e x c e p t f o r t h e N E R V A / p r o p u l s i o n m o d u l e t a n k a g e m a t i n g o p e r a t i o n , w h i c h would p r o b a b l y be a c c o m p l i s h e d m o s t e a s i l y w i t h b o t h e l e m e n t s in a v e r t i c a l p o s i t i o n in a low b a y checkout cell. 148
18107 FACILITIES DEFINITION PRIMARY FACILITY REQUIREMENTS ® MANUFACTURING FLOOR SPACE CLASS 1 HYBRID CLASS 3 APPROX 145.000 FT^ ~ APPROX 92,000 FT^ ® KSC FACILITIES CLASS 1 HYBRID - CLASS 3 2 VAB LOW-BAY AREAS. 1 HIGH-BAY CELL - MOBILE LAUNCHER SWING-ARM MODIFICATION - MINIMAL LAUNCH CONTROL CENTER MODIFICATIONS - 3 VAB LOW-BAY AREAS FACILITY UTILIZATION STATUS # MICHOUD - CLASS 1 HYBRID PROPELLANT MODULE FINAL ASSEMBLY NO MAJOR FACILITY MODIFICATIONS REQUIRED PORTIONS OF BUILDINGS 103 AND 110 WOULD BE UTILIZED SHUTTLE MANUFACTURING AT MICHOUD IS POTENTIAL PROBLEM ON JOINT UTILIZATION OF BUILDING 110 # MDAC-HB - CLASS 1 HYBRID PROPULSION MODULE AND COMMAND CONTROL MODULE MANUFACTURING NO MAJOR FACILITY MODIFICATIONS REQUIRED - CLASS 3 MANUFACTURING {ALL MODULES) NO MAJOR FACILITY MODIFICATIONS REQUIRED # MTF ~~ PRODUCTION ACCEPTANCE TESTING OF CLASS 1 HYBRID PROPELLANT MODULES FACILITY MODIFICATIONS DEPENDENT UPON NATURE OF SPACE SHUTTLE TEST PROGRAM AT MTF 149