The results of systems analysis conducted on low life drag ratio (L/D) aero-assisted orbit transfer vehicle (AOTV's) are presented. The objectives for this class of vehicle and formulate technology development plans and funding levels to bring the required technologies to readiness levels, as well as develop a credible decision data base encompassing the entire range of low L/D concepts for use in future NASA Aeroassist Orbit Transfer Vehicles studies. Each candidate low L/D concept, the aerobrake, the lifting brake, and the aeromaneuvering concept could be made to work with technologies achievable by the early 1990's. All concepts require flexible structure with flexible thermal protection system (TPS) to be successfully integrated into the shuttle orbiter for launch, all required improvements in guidance and control to fly the dispersed atmospheres at high altitude, and all concepts had potential to evolve from ground-based to space-based operations

Andrews, D. G.

Savage, R. T.

English

NASA Technical Reports Server

LOW LIFT-TO-DRAG AERO-ASSISTED ORBIT TRANSFER VEHICLES 
Dana G. Andrews and Richard T. Savage 
Boeing Aerospace Company 
The r e s u l t s  o f  a  systems a n a l y s i s  s tudy  conducted on low L/D 
aero -ass is ted  o r b i t  t r a n s f e r  v e h i c l e s  (AOTV1s) i s  presented.  The o b j e c t i v e s  
o f  t h i s  a c t i v i t y  were t o  (1)  s y s t e m a t i c a l l y  assess t h e  techno logy  requi rements  
f o r  t h i s  c l a s s  o f  v e h i c l e  and f o rmu la te  techno logy  development p lans  and 
f und ing  l e v e l s  t o  b r i n g  t h e  r e q u i r e d  t echno log ies  t o  readiness l e v e l s ,  and ( 2 )  
develop a  c r e d i b l e  d e c i s i o n  da ta  base encompassing t h e  e n t i r e  range o f  l o w  L / O  
concepts f o r  use i n  f u t u r e  NASA AOTV s t u d i e s .  
The s tudy  approach was t o  s e l e c t  s u i t a b l e  AOTV concepts,  address major  
f e a s i b i l i t y  i ssues ,  and generate  workable c o n f i g u r a t i o n s  f o r  use i n  
t r a j e c t o r y /  aerothermal  analyses.  Subsystem t r ades  examined t h e  impact  o f  
d i f f e r e n t  techno logy  l e v e l s  on v e h i c l e  performance and noted t h e  l e v e l s  
r e q u i r e d  t o  meet bas i c  ope ra t i ng  requi rements .  F i n a l l y ,  t echno log ies  were 
ranked i n  o r d e r  o f  importance towards meet ing low L/D AOTV des ign goa ls ,  and 
program and techno logy  f und ing  cos t s  were es t imated .  
Study r e s u l t s  showed t h a t  each o f  t h e  cand ida te  low L/D concepts,  t h e  
aerobrake, t h e  l i f t i n g  brake, and t h e  aeromaneuvering concept cou ld  be made t o  
work w i t h  t echno log ies  ach ievab le  by t h e  e a r l y  1990 's .  A l l  o f  t h e  concepts 
r e q u i r e d  f l e x i b l e  s t r u c t u r e  w i t h  f l e x i b l e  thermal  p r o t e c t i o n  system (PPS) t o  
be s u c c e s s f u l l y  i n t e g r a t e d  i n t o  t h e  s h u t t l e  o r b i t e r  f o r  launch, a l l  r e q u i r e d  
improvements i n  guidance and c o n t r o l  (G&C) t o  f l y  t h e  d ispersed  atmospheres a t  
h i g h  a l t i t u d e ,  and a l l  concepts had p o t e n t i a l  t o  evo lve  f rom ground-basea t o  
space-based opera t ions .  
The c r i t i c a l  advancements i n  t echno log ies  r e q u i r e d  t o  implement t h e  low 
L/D AOTV concepts were i n  TPS, e s p e c i a l l y  f l e x i b l e  TPS, i n  aerothermal 
p r e d i c t i o n  methods, and i n  G&C. Other  areas where techno logy  advancements 
appeared t o  be c o s t  e f f e c t i v e  ( i . e . ,  sav ings i n  use outweighted development 
c o s t s )  were p ropu l s i on ,  atmospher ic phys ics  ( p r e d i c t i o n  methods), r a ~ r i f i e d  gas 
aerodynamics, and composite s t r u c t u r e s .  
https://ntrs.nasa.gov/search.jsp?R=19850008685 2020-03-20T20:39:03+00:00Z
Study  Objectives 
4) DEFINITION OF A TECHNOLOGY PLAN FOR LOW L ID  AOTV'S 
@8 ENABLING AND HIGH PAYOFF TECHNOLOGIES IDENTIFIED 
REALiSTlC CONSTRAINTS ON TECHNOLOGY FUNDING LEVEL ASSUMED 
B TIME PHASED PLAN DEVELOPED FOR REASONABLE IOC DATE 
@ DEVELOPMENT OF A DECISION DATA BASE FOR FUTURE NASA AOTV STUDIES 
e INVESTIGATE CONCEPTS Tt-IROUGHOUT THE ENTIRE LOW L ID  RANGE 
@ ADDRESS THE CRITICAL VEI-IICLE TECttNDLOGlES 
a INCLUDE OPS ANALYSES 
@ DEVELOP EVOLUTIONARY GROWTH SCENARIOS 
ESTIMATE COSTS INON.RECURRING, RECURRiNG AND OPS) 
Figure 1 
Technical Approach 
@ SYSTEMS TRADES 
r SELECT CANDIDATE CONCEPTS AND RESPOND TO FEASIBILITY ISSUES 
s, USE WORKABLE CONFIGURATIONS I N  TRAJECTORY/AEROTHERMAL ANALYSES 
r USE MANNED MISSION TO DESlGN ALTERNATE OPERATIONAL MODES 
@ SUBSYSTEM TRADES 
* BUILD FROM PHASE A-OTV DATA BASE 
r INCORPORATE ADVANCED TECHNOLOGIES 
ASSESS TECCINOLOGY PAYOFFS 
@ TECHNOLOGY PLANNING 
s IDENTIFY CURRENT, NORMAL GROWTH, AND ACCELERATED GROWTH 
TECHNOLOGIES 
c RANK TECHNOLOGIES WITH RESPECT TO PROGRAM REQUIREMENTS 
* PLAN TECHNOLOGY DEVELOPMENT 
8 COST ANALVSES 
o USE WORK BREAKDOWN STRUCTURE 10 ESrlMATE SUBSVSTEM COSTS 
e ESTIMATE PROGRAM COSTS 
o ESTIMATE TECHNOLOGY FUNDING REQUIREMENTS 
F i g u r e  2 
58 
Design Mission Requirements 
@ BASELINE DESIGN MISSIONS (65K STS) 
0 GEO DELIVERY 
0 6 x GEO DELIVERY 
0 6 HR. POLAR DELIVERY 
@ EVOLUTIONARY GROWTH MISSIONS 
0 UNMANNED SERVICING (NOT A DESIGN DRIVER) 
0 MANNED GEO MISSION (KEY DESIGN MISSION I N  A L L  MODELS) 
e 14,000 LB. ROUND TRIP 
e REQUIRES ALTERNATE OPERATING MODE 
0 BASIC TECHNOLOGY TRADES WERE DONE USING VEHICLESSIZED 
I-OR BASELINE MISSIONS 
0 MANNED GEO MISSION WAS USED TO SIZE EVOLUTIONARY GROWTH 
CONFIGURATIONS AND DETERMINE WORTH OF ALTERNATE 
OPERATING MODES 
2 
Figure 3 
Low L/D AOTV Characteristics 
(BASELINE CONCEPTS) 
AEROBRAKE (LID-0) LIFTING BRAKE (L/D=0.25L AEROMANEUVFRING (L/Q=O.?a 
BALLISTIC 
COEFFICIENT.W- 5-10 PSF 5.10 PSF 
CD A 
25-45 PSF 
CONTROL VARIABLE C A MOVEMENT QF CG VARIABLE BANK ANGLE 
TEC~INIOUE USING INTEHTJAL IN Y - - Z  PLANE USING AEIJUNDANT PRESSURE USING ELECl ROMECHNI.CAL RCS THRUSTERS 
ACTUATOHS 
METHOD OF NONE 
AERODYNAMIC TRIM (STABLE) SAME AERODYNAMIC TRIM SURFACES 
KEY 
ISSUES 
GUIDANCE & CONTROL GUIDANCE & CONTROL TRANSPIRATION COOLING OF 
IN  3GATMOSPtiERE IN  36ATMOSPHERE NOSE CAP 
DYNAMIC STABILITY FLOW INPINGEMENT THERMAL CONTROL 
OF INFLATED STRUCTURE ON BODYIPAYLOAD 
Figure 4 
Lifting Brake Configuration 
PROPOSED DESIGN FINAL BASELINE 
MAJOR MAJOR 
CHANGE: CHANGE: 
I) 
NON POROUS 
I) 
EDGE 
&4 RADIUS 
INFLATABLE 
BRAKE 
AREAS OF CONCERN 
-- 
as YaEPLC"dME%dT MECHANISM 
a POWOhdS HEAT SHIELD 
dB E A N K  ANGLE CONTROL 
@ SUlDBrh'CE & CONTROL I N  
36-AT rdQSBHERE 
B i  FLOW IMPINGEMENT 
O h  BODVIPAYLOAD 
AREAS OF CONCERN AREAS OF CONCERN 
@ NO RETURN PAY LOAD s CONTROL w i T n  RETURN 
@FLOW IMPINGEMENT PAY LOAD 
ON BODV/PAYLOAD B STS INTEGRATION 
B, G&C IN WATMOSPHERE 
@ STS INTEGRATION 
a NON-POROUS FABRIC: BOUNDARY LAYER 
TEMPERATURE CONTROL 
Figure  5 
Aeromaneuver Configuration 
STUDY lNlTlATlON 
r- 
BASELINE 
MAJOR 
CHANGE: 
INFLATABLE 
NOSE, 
TRANSPIR - 
ATION 
COOLED 
AREAS OF CONCERN 
&TRANSPIRATION COOLED 
NOSE 
RATIONALE FOR CHANGE 
F i g u r e  6 
60 
Aerobrake Configurations 
STUDY INITIATION BASELINE 
0 JET COUNTERFLOW 
INTERACllION * 
@FLEXIBLE TPS 
0 INFLATE0 
STRUCTURE 
STABILIT'I 
AREAS OF CONCERN 
0 DYNAMIC STABILITY OF 
INFLATED STRUCTURE 
G U I D A N C E  & CONTROL 
I N  3fATMOSPHEHE @INFLATED STRUCTURE 
.INTERACTION BETWEEN STABILITY 
BALLUTE, JET COUNTER- 
FLOW, & FREE STREAM 
FLOW 
. FLEXIBLE TPS 
0 TESTING OF FLEXIBLE BALLUTE AND TPS PRODUCED NO BALLUTE "SHOW STOPPERS'" 
0 ALTERNATIVE PROPOSED TO ELIMINATE JET COUNTEHFLOW UNCERTAINTY 
F i g u r e  7 
System/Concept Findings 
@ NONE OF LOW LID CONCEPTS ELIMINATED BY TECHNOLOGY ISSUES 
@ MUCH OF THE TECHNOLOGY REQUIRED IS COMMON 
g ALL  CONCEPTS SIGNIFICANTLY BETTER UNDERSTOODIIMPROVED 
0 PERFORMANCE AND OPERATIONAL FLEXIBILITY ADVANTAGE TO AEROBRAKE 
LIFTING BRAKE AND AEROMANEUVERING APPLICATIONS LIMITED BY AFT C.G. AND/OR 
FLOW IMPINGEMENT CONCERNS 
0 ALTERNATE OPERATIONAL SCENARIOS 
e ACC: EXCELLENT CONFIGURATION FOR LIFTING BRAKE; NO SIGNIFICANT IMPACT 
ON AEROBRAKE; AEROMANEUVERING IS NOT APPLICABLE 
@ SPACEBASING/MANNED MISSION: NOT A SIGNIFICANT DISCRIMINATOR EXCEPT FOR 
PERFORMANCE 
SOCLV: ATTRACTIVE OPTION WITH AEROASSIST 
@ FOR ALL  CONCEPTS THE MAJOt7 UNRESOLVED ISSUES CONCERN REAL GAS FLOW EFFECTS 
AND THE DYNAMICS OF FLEXIBLE STRUCTURE AT THESE CONDITIONS 
e MORE TESTING REOUIHED TO PROVIDE DESIGN DATA 
9 FLIGHT EXPERIMENTS NEEDED TO RESOLVE ALL  DOUBTS 
FOR ALL  CONCEPTS UPPER ATMOSPHERIC DISPERSIONS ARE A MAJOR DESIGN DRIVER 
DESIGN DATA NEEDED -SOME TESTING REQUIRED 
e FLIGHT EXPERIMENTS IMPORTANT TO PROVE GN&C SYSTEMS 
@ NO SIGNIFICANT COST DISCRIMINATORS FOUND BETWEEN LOW LID CONCEPTS 
F i g u r e  8 
Technology Drivers 
TECHNOLOGY ISSUE 
-
COMMENTS 
THERMAL BEAK TEMPERATURE NEED TO ACCELERATE TECHNOLOGY GROWTH 
PROTEGTlOFd CAPABILITY OF FLEXIBLE SURFACE INSULATION (FSIJ 
AEROTHERMAL THERMAL ENVIRON- INCREASED ACCURACY IS REQUIRED TO FULLY 
METHODS MENT PREDICTION CHAHACTEt?IZE THERMAL EhV1RONMENT 
ATMOSPtiERlC AEROPASS REQUIRES MORE ADVANCED ADAPTIVE 
GUIDANCE GUIDANCE SYSTEM 
PROPULSION HIGHER PERFORM- 
ANCE ENGINE 
ATMOSPHERIC HIGH ATMOSPHERE 
PHYSICS DESCRIPTION 
AERODYNAMlCS RAREFIED FLOW 
EFFECTS 
STRUCTURES STRUCTURAL 
WEIGHT REDUCTION 
DEVELOPMENT OF AN ADVANCED LHZ/L02 HlGHEA 
ENGINE IS COST EFFECTIVE 
BETTkR UNDERSTANDING OF THE: UPPER 
ATMOSPHERE SIMPLIFIES GN&C AND THERMAL 
PROBLEMS 
ENHANCE GUIDANCCSYSTEM ACCURACY 
UTlLlZlNG ACCELERATED TECHNOLOGY GROWTH 
IS  COST EFFECTIVE 
Technology Ranking 
a DEVELOP TRANSPIRATION COOLING 
AEROTHEWMAL METHODS 0 BLUNT BODY FLOW UNDERSTANDING 
WITH AND WITHOUT JET COUNTERFLOW 
6 BOUNDARY LAYER TWANSITlON GRlTERlA 
c NQN.EOUIILIBRIUM WADlATDOM 
OPTIMAL GUIDANCE APPROACHES 
" CONTROL FUNCTION DEVELOPMENT 
- SVSTEU VALIDATION 
ATMOSHERIG PHYSICS a TETHER DATA ANALYSIS 
8 LASER RALEIGH BACKSGAnER 
AEWODYNrnICS 6 DETERMINE RAWEFlED FLOW EFFECTS 
Figure 10 
6 2 
Technology Plan Summary 
0 REASONABLE DEFINITION OF TECHNOLOGY REQUIREMENTS AND OBJECTIVES 
0 CLEAR DISCRIMINATION BETWEEN REQUIRED VERSUS ENHANCED TECHNOLOGIES 
@ ENABLING TECHNOLOGY PROGRAM CAN BE ACCOMPLISHED TO SUPPORT PROGRAM 
START IN LATE 1980's FOR APPROXIMATE TOTAL $ = 65.6 MILLION 
FLIGHT DEMONSTRATION EXPERIMENT($) EXTREMELY DESIRABLE-POWERFUL 
BENEFITS- 
0 DEMONSTRATES GN&C CONCEPTS AND ALGORITHMS 
PROVIDES NEEDED AERODYNAMICSIAEROTHERMAL DATA 
0 VERIFIES DYNAMICSTABILITY OF FLEXIBLE BALLUTE 
e VERIFIES TPS PERFORMANCE I N  ACTUAL FLIGHT ENVIRONMENT 
e ENHANCING TECHNOLOGiES APPEAR TO HAVE HlGH PAYOFF (NOT QUANTIFIED 
IN ALL  CASES) 
@ THIS IS STILL A "FIRST CUT" PLAN AND NEEDS ITERATION 
AOTV Thermal Criteria 
SURFACE TEMPERATURE - 100 REUSES 
TPS MATERIAL IBBO TECHNOLOGY I1886 IOCI 
CURRENT TECHNOLOGY 
FLEXIBLE SURFACE 1600°F - lBOo°F 
INSULATION (FSII 
RIGID SURFACE 
INSULATION IRSI) 
HlGH DENSITY 
REFRACTORY (HOR) 
BACKWALL TEMPERATURE 
HIGHER TEMPERATURE STRUCTURES ARE POSSIBLE. BUT ARE NOT 
CONSIDERED ADVANTAGEOUS BECAUSE OF THERMAL CONTROL 
CONSTRAINTS 
MATERIAL 
GRAPHITEIPOLYIMIDE * 
KEVLAR CLOTH 
Figure  1 2  
MAXIMUM TEMPERATURE 
600' F 
600' F 
Flexible Surface InsuBation TechnoPo~y Assessment 
~ ~ C L U D E S  50% FAC i on FOR NE RADIATION, ETC. 
EMlTTAMCE - 0.8 A NO LlFT 
LIFTING BRAKE 
TECHNOLOGY 
1 
Figure 13  
Rigid Surface Insulation Technology Assessment 
" Ttamaaxu-*'L ***amaems 
EWIITTWNCE = 0.8 
INCLUDES 50% FACTOR FOR NE RADIATION. ETC. 
A NO LlFT 
O SIDE LIFT (BANK = 00") 
0 DOWN LIFT {BANK - 180") 
LOFTING BRAKE AEROMANEUVERINC 
I I 
Figure 14  
High Density Refractory Technology Assessment 
NORMAL 
GROWTH 
CURRENT 
TECHNOLOGY 
EMITTANCE - 0.8 
INCLUDES 50% FACTOR FOR NE RADIATION, ETC. 
A NOLlFT - 
0 SIDE LIFT (BANK - 000) 
a DOWN LIFT (BANK - 180°) 
NORMAL GROWTH TECHNOL.OGY OK 
AEROBRAKE 
(NOSE CAP) 
A 
6 x GEO 
UNMANNED 
A 
1 x GEO 
UNMANNED 
F l g u r e  1 5  
Examples of High Payoff Technology Assessment 
LIFTING BRAKE 
(NOSE CAP) 
ACCELERATED GROWH TECHNOLOGY COST EFFECTIVE FOR AOTV'S I 
AEROMANEUVERING 
(OTV CORE) 
SUBSYSTEM 
ACCELERATED GROWTH 
STRUCTURAL 
COMPONENTS (10% 
WEIGHT REDUCTION) 
NORMAL GROWTH 
EXPANDER CYCLE 
ENGINE (480 SEC ISP) 
ACCELERATED GROWTH 
EXPANDER CYCLE ENGINE (490 SEC ISP) 
b COSTS BASED ON 6 FLIGHTS/YEAR FOR TEN YEARS lNOM MISSION COST- $81.BM) 
b BASELINE LCC- S6,632M, BASELINE GEO PAYLOADS - 526,400 LB (10,700 $/LB) 
IS> TECHNOLOGY DEVELOPMENT FINANCED BY OTHER PROGRAMS 
0 
6 x GEO 
MANNED 
UNMANNED 1 x GEO 
1 x GEO MANNED 
MANNED , 
F i g u r e  16 
DELTA GEO 
280 LB 
1330 LB 
1.W3 LB 
DELTA 
TECHNOLOGY 
DEV COST 
rD 
E 8M 
S l l M  
DELTA DDT&E 
COST 
$ 35M 
$430M 
$630M 
GEO PAYLOAD 
COST 
D 
10,490 WLB 
10,013 S/LB 
9,802 WLB 
P 
RELATIVE 
SAVINGS 
!D 
210 SlLB 
I 
887 I i l 0  I 
I 
8Q8 blLO 
c AEROBRAKED AOTV IS RECOMMENDED CONCEPT IF  DEVELOPMENT WERE TO START 
TODAY 
e BEST PERFORMANCE, LEAST COST, MOST STS COMPATIBLE, ETC. 
s CONTROL METHOD REOUIRES MORE DEVELOPMENT (NEEDS TESTING) 
a REUSABLE TPS (RIGID AND FABRIC) WITH CAPABILITY TO 300Q°F 
r MORE ACCURATE AEROTHERMAL PREDICTION METHODS 
GN&C SYSTEMS SUITABLE FOR AEROASSIST REENTRY TRAJECTORIES 
e ADVANCED EXPANDER CYCLE ENGINE TECHNOLOGY 
@ IF SPACE BASING BECOMES PRIMARY OPERATING MODE THEN A SPACE ASSEMBLED 
LllT'TIYdG BRAKEIAEROMANEUVERING CONCEPT SHOULD ALSO BE PURSUED 
PA DESIGN FOR COMPLETE REUSABILITY 
s USE L I D  TO REDUCE PROPULSlVE AV, PEAK HEATING, AND EFFECT OF 
ATMOSPHERIC DISPERSION 
F i g u r e  1 7  
Fresh Look Lifting Brake Designed for Space Assembly 
@ ST§ COMPATIBLE OTV MOUNTED 
USING SI-IUTTLE FIXTURES 
ttb OTV JAN BE EITHER GROUND 
BASED OR SPACE BASED 
@ NO NOZZLE RETRACTION REQUIRED 
GWiJSS TRIM ACCOMPLISHED BY 
SLIDING OTV ON RAILS 
@ COMBINE BEST FEATURES OF LIFTING 
BRAKE & AMOTV 7 0  INCREASE V D  
AND REDUCE SCAR WEIGHT 
O SPACE ASSEMBLED PREFABRICATED 
COMPOSITE PANELS 
@ RIGID ,OR FABRIC REUSABLE TPS 
LARGE PLANFORM AREA REDUCES 
TEMPERATURES 
O NO IMPINGEMENT PROBLEM 
## COIVTROL WITH AERODYNAMIC SURFACES 
& 696s 
F i g u r e  18 
66 
Objectives of Follow-on Study 
0 DESIGN DEVELOPMENT OF SPACE ASSEMBLED LIFTING BRAKE CONCEPT 
0 FURTHER APPLICATION OF OPTIC GUIDANCE CONCEPT TO GN&C TRADES 
e AEROBRAKE CONCEPT 
e L IFTING BRAKE CONCEPT 
0 PROPULSION SYSTEM TRADES 
* SIZE AND NUMDER OF ENGINES OPTIMLJM FOR AOTVr 
* TECHNOLOGY LEVELS OPTIWIUM FOR LCC 
0 TECHNOLOGY DEVELOPMENT PLANNING 
ATMOSPHERIC DISPERSION TESTING 
e TPS . 
e AEROTHERMAL 
* AERODYNAMICS 
Figure 19 


Low lift-to-drag aero-assisted orbit transfer vehicles

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