The RD-170, a Different Approach to Launch Vehicle Propulsion

AIAA 93-2415 The RD-170, A Different Approach to Launch Vehicle Propulsion

Boris I. Katorgin and Felix J. Chelkis NPO Energomash, Khimky, Russia Charles D. Limerick Pratt & Whitney, West Palm Beach, Florida

AlANS A €/AS MWAS E E 29th Joint Propulsion Conference and Exhibit June 28-30, 1993 / Monterey, CA

For permisslon to copy or republish, contact the American Instltui. J Aeronautics and Astronautics 370 L'Enfant Promenade, S.W., Washlngton, D.C. 20024 The RD-170, A Different Approach to Launch Vehicle Propulsion 'LJ Boris I. Katorgin' and Felix J. Chelkis** NPO Energomash Khimky. Russia

Charles D. Limerick"* Pratt & Whitney West Palm Beach, Florida

Abstract Introduction

In the early 1960's, the United States and The RD-170 is a mature engine. U.S.S.R. took different paths in developing Development started in 1976 and the first launch vehicle propulsion. The United flight was in 1985. Over 200 engines have States focused on the lower performance been built and over 900 tests accumulating gas generator cycle rocket engine because more than 100,000 sec have been of the less demanding technology involved completed. The RD-170 is a total and the resulting easier development propulsion unit with hydraulics for control process. The U.S.S.R. adopted the high valve actuation and thrust vector control performance staged combustion cycle with gimbaling, pneumatics for valve actuation oxygen rich turbine drive gases and have and purging, and a thrust frame to since striven to perfect that system. The distribute loads all self contained as part of RD-170 is the culmination of over 30 years the engine. The engine was developed to LJ of staged combustion cycle propulsion provide the booster propulsion for the system development. This paper discusses Energia and Zenit launch vehicles. One of the evolution of high pressure the requirements of the Energia application turbomachinery and combustion chamber was reusability, the RD-170 strap-on designs from the RD-253 (the first booster units were intended to be used up operational high pressure staged to 20 times without overhaul or removal combustion rocket engine, introduced in from the booster stage. Hence, along with 1965) to the RD-170. The operating the traditional requirements of high characteristics of the RD-170 will be performance and reliability were reusability explained along with the operability and operability requirements not previously features included as part of the engine demonstrated in rocket engines. It was system. The quality approach used in the required that between flight servicing and manufacturing, component test, and initial flight preparation be accomplished assembly process will be described and the using a minimum of hand operations. unique health monitoring and life prediction system will be unveiled. Potential The engine is the current product of an application of the RD-170 to US. launch engine design philosophy initiated with the vehicle needs has been studied and these RD-253 engine which started development results will also be presented. in the early 1960's. NPO Energomash embarked on a course to develop high General Director and General Designer pressure, staged combustion, oxidizer rich ** Chief Designer turbine drive gas rocket engines, and the ***Manager, SE&I, Russian Programs RD-253 which became operational in 1965 Member AlAA was the first engine of this type. This L,

engine which operated at over 2000 psia advanced health rnonitoring/life prediction " using the staged combustion cycle was as system. Development of the engine was far in advance of other engines of that initiated in the mid 1970's with the first flight generation as the RD-170 is relative to the occurring in 1985. The quality control current generation of engines. Figure 1 system and specifications were developed shows the chamber pressure versus time from strong requirements close to U.S. characteristics of some representative NPO standards. The extensive NPO Energomash developed engines with the Energomash experience, the 4 chamber US. developed F-I and SSME noted for modular configuration of the engine, and reference. development of a wide range of similar turbopumps of different thrust sizes provides confidence in low risk, low cost development of Derivative Configurations (1 chamber, 2 chamber, uprating, etc.).

4000 The RD-170 engine assembly shown in Figure 2 consists of a single high-pressure 3000 turbopump assembly driven by two Engine preburners, four injector/thrust chamber chamber assemblies, integral fuel and oxidizer boost pressure 2040 pumps, helium bottles for valve actuation

1000 and start and shutdown purging, thrust structure, gimbal actuators, propellant ducting, hypergolic-fuel cartridges, 0 sequencing and control valves, shielding, w- and telemetry systems. 20996A Figure 1 Rocket Engine Development History

RD-170 Enqine Characteristics

The RD-170 is a high performance lox/kerosene rocket booster propulsion system with operability and reusability features not previously demonstrated on rocket propulsion systems. The engine was designed to provide a minimum of 20 reuses before overhaul and enable lj between flight servicing and initial flight preparation with automated operations.

The operability of the RD-170 is a major contributor to the less than 7 day launch timeline of the Zenit launch system. The engine is >IO% higher in performance than other loxlkerosene booster engines and Figure 2 v has a fully developed, operational, RD- 170 Propulsion Assembly

2 The RD-170 is a staged combustion cycle LodKerosene booster rocket propulsion assembly producing 1.6 million Ibs sea level thrust and a sea level impulse of 309 sec at an overall mixture ratio of 2.6 to 1. It has a 2 to 1 throttling range, an assembly dry weight of 26,575 Ibs and overall dimensions of 157.9 inches length and 146 28'JWA inches diameter. The single high-pressure Figure 4 turbopump assembly feeds four identical RD-170 Flow Schematic injector thrust chamber assemblies. Two preburners are used to drive the single The fuel and oxidizer boost pumps are stage turbine with oxidizer rich combustion integrated into the inlet lines and are driven products. with turbine discharge gas (oxidizer) and recirculated fuel (fuel) that reenters the The high pressure turbopump assembly, propellant flow upstream of the high- shown in Figure 3, consists of two rotors pressure pumps. The four injector/thrust connected by a quill shaft. One rotor has chambers are each integrally the turbine and oxidizer pump and the other welded/brazed assemblies with hypergolic the fuel pumps. Both shafts operate with ignition and a combination of film and subcritical rotor dynamics. regenerative cooling (shown in Figure 5). All four injector chamber assemblies can gimbal in two directions or can be limited to -i/ a single direction by installing a fixed link. The linear actuators are powered by fuel- supplied by the high pressure fuel pump. The two parallel preburners are ignited by a unique single-shot hypergolic ignition system.

Figure 3 High Pressure Turbopump Assembly

All oxidizer flows through the preburners but the fuel is split between the preburners and chambers (fuel cooled). Thrust control is achieved by regulating fuel flow to the 20987A preburners, and mixture ratio by regulating fuel flow to the chambers. An engine flow schematic with only two chambers shown is Figure 5 presented in Figure 4. Injectorflhrust Chamber Assembly

3 Control valve command signals are Table 2 " generated by a vehicle computer running sofhrvare generated during engine RD-170 Characteristics acceptance testing. Heated helium is supplied from the engine for oxidizer tank . Nominal thrust (S.L.) 1,632,000 Ib pressurization. The engine is reusable and . (Vacuum) 1,777,000 Ib over 20 repeat firings have been performed . Specific impulse (S.L.) 309 sec on ground test engines. The health . (Vacuum) 337 sec monitoring system automatically assesses . Chamber pressure 3,560 psia engine health and defines/tracks remaining . Nozzle area ratio 36.4:l engine life. The RD-170 has completed 28 . Mixture Ratio 2.6 flight firings (20 ZENIT and 8 ENERGIA) . Length 157.9 inches and over 900 test firings with an . Diameter (148.8 frame/ accumulated total of over 100,000 146 nozzles) inches operational seconds. . Throttle range 50-105 Yo Total system dry weight 26,575 Ibs Table 1 provides a general description of . the RD-170 and characteristics are presented in Table 2. Operability Features Table 1 The RD-170 was designed for operability, RD-170 General Description wherever possible flight preparation, and between flight operations (for reusable w0 Staged combustion cycle engine applications) have been minimized and . LoHkerosene propellants automated. After installation in the vehicle, . 4 thrust chambers (gimbal+W) all engine operations are automated . 2 oxygen rich prebumers through the launch phase. The engine . High pressure turbopump assembly requires minimal preparation for launch as - 2 stage fuel pump shown in Table 3. - single stage oxygen pump - single turbine Hydraulic system (valves, TVC) Interfaces are minimized and there are no powered with kerosene from fuel pump flexible interfaces with the vehicle. The . Hypergolic ignition hydraulics systems for the control valves . Operational certification 1985 and thrust vector control are self contained . 200+ engines produced as part of the engine with hydraulic power . > 100,000 sec and > 900 firings furnished with kerosene from the high . 28 flight firings (December 1992) pressure fuel pump. There are no - 20 Zenit hydraulic interfaces with the vehicle or pad. - 8 Energia . Qualified for 10 mission reusability . Fully developed health monitoring/life prediction system

4 Table 3 be used to provide real time trajectory L/ matching during the boost phase. This RD-170Launch Preparation would enable a significant reduction in avionics programming, significantly At the engine factory before shipping improving the operability of the launch Line closeouts. chamber throat plugs, and system. hypergolic start cartridges installed In the vehicle assembly building Health MonitorinslLife Prediction System Continuity and function checks as part of vehiclelengine assembly process Evaluation of the engine technical state All automated operations on pad after firing or flight use is accomplished Helium bottles filled Low level GN2 purg,e and low level dry air purge using a technical diagnostics system (TDS), at start of LOX tankina which deals with measured engine LOX cooldown by ~circulatlon(15 min after parameters. completion of tanking) Fuel GN2 ejector for 10 min Control valve hydraulic system prepressurized The TDS uses both static and dynamic 100 sec to fill fuel system (fuel prevalve opened) parameters of the engine and consists of Hydraulic control valves positioned 60 sec the following subsystems: before start Hiah level GN7 fuel side purge 20 sec before L .- start Helium bottle pressure, hydraulic control valve static parameters diagnostics position, and GN2 ejector operation monitored (pressure switches) subsystem for evaluating measurement validity Darameters algorithm evaluation Helium for pneumatic valve actuations and purging during the shutdown is also self- contained as part of the engine. This dynamic parameters diagnostics system is automatically filled through a pad interface during the launch preparation vibroacoustic characteristics evaluation process. subsystem for estimating expired life time The comprehensive health monitoring and life prediction was designed and the Full cycle of calculations and analysis for all necessary data base compiled during subsystems can be performed within a day development to provide automated after engine testing. reusability of the engines for Energia. The projected launch rates have not All subsystems use measurements of all materialized for Energia and reuse of the engine parameters during a test (or a booster modules was never attempted; flight). Total number of measurements is however, the engine has been qualified for about -150. 10 reuses (17 with 5 mission margin and 2 firings in acceptance). A diagram visually presenting the health monitoring life prediction process is shown The continuous throttling capability of the in Figure 6. RD-170 to less than 50% also provides potential operability advantages. The engine could be started to a low thrust level and checked out prior to committing to launch. The throttling capability could also

5 ., . Allowed limits for diagnostic indicators were ...... I ...... ,,~=.. ____...... , ly,. I... -. ... __ defined by statistical modeling. In order to i Automated Analysis make a formal decision concerning a state a* 01 "mn P.n-1. of engine components, a special logical : Y*rUr*yl.rn*"n state model is used. All evaluation and formal analysis procedures are performed with special software on computers of IBM 360/370 type.

Dynamic Parameters Diagnostics

Vibroacoustic Characteristics Evaluation - This subsystem evaluates vibroacoustic characteristics of engine parameters -- . I obtained on start-up mode, nominal mode, I_ smooth throttling mode, and final stage mode. The amount of parameter characteristics, which are calculated and Figure 6 evaluated, totals 100. Allowable Health Monitoring/Life Prediction Process characteristics limits are obtained from statistics. Static Parameters Diaanostics Characteristics are calculated and Subsystem for Evaluating Measurement compared with allowable limits by special Validity - This subsystem evaluates equipment complex, which. consists of -' parameters, which were recorded during spectrum analyzer and a personal engine operation in start-up, steady state, computer connected to it. This computer smooth throttling, final stage, and shutdown enables the use of spectrum analysis for modes. Totally, this subsystem evaluates calculations. The process uses special over 100 engine parameters. software for calculating and analyzing vibroacoustic characteristics. In the event that some parameters are beyond allowable statistical limits, the Subsystem for Estimating Expired Life Time causes of why these parameters are out of - This subSystem evaluates an engine state the limits are analyzed by a special logical based on expired life time by the end of the model. The procedure of evaluating current engine test during all life cycle. parameter values and their derivatives and Amount of evaluated parameters (which a formal analysis of causes of parameters are called "accumulated damage owing to being out of limits are fully automatic and expiring main engine aggregates life time") performed by means of a special software totals 70. Allowed limits for these for computers of IBM 360/370 type. parameters are set based on results of durable engine life time testing cycles Parameters Algorithm Evaluation - The during development, and on certification engine diagnostics for this evaluation is and reliability confirmation test results. The performed on the main mode for 17 engine "accumulated damage" is calculated by the subsystems for 30 diagnostic indicators. same equipment complex as for These diagnostic indicators are calculated vibroacoustic characteristics control and by a mathematical model using engine stability subsystem. There is a software for parameters measured during operation. calculating "accumulated damage" at the b end of each testing.

6 a customer. For controlling the process of Qualitv Amroach developing manufacturing processes for u engine components and engine system, the Quality control system at NPO Energomash Experimental Plant develops a meets Is0 9000 series standards development program for technological requirements. Quality control system processes. This program is agreed upon procedures are implemented during project by the Design Bureau and a scientific development, working documentation technological institute. Results, reached at development, manufacturing, and testing of design development stages, are reflected in engine components and the engine system. design bureau reviewing reports. Results of manufacturing processes development Project Quality are certified by engaging specialized industry branch scientific institutes. At NPO Energomash, input data for a project ("technical task") are considered by Manufacturinq and Testinq all departments, which participate in the project. Results of such a consideration All materials, purchased parts, semi- are certified by department chiefs' finished items, which are supplied to the signatures. A technical task is agreed upon company, are subject to input control. by scientific organizations. Requirements, Control procedures are provided by which are included in a technical task, industry branch and company standards. should meet the State Standard for Liquid Rocket Engine Reliability. All parts and subassemblies during the manufacturing process are subject to Development materials ("technical control procedures by Technical Control . W proposal," "sketch project") are subject to Department employees. Controlling standard control procedures, during which operations are an integral part of the a project is checked for whether manufacturing process. The fact of requirements of Single Design passing through a control operation is Documentation System State Standard are certified with a mark in documentation for met. Then a project is directed to scientific the part by the controller. Periodically units organizations that investigate it. and subassemblies are assembled and disassembled for the purpose of control. Documentation Quality . Subassemblies that have independent specifications are subject to product During development all documentation acceptance tests (each specimen should passes through a multi-stage quality control be tested) or selective tests (selective process: first, it is controlled by an specimen of a batch should be tested). executor, then by a controller, and managers up to Design Bureau Chief. The All waivers from a documentation are documentation is controlled by the considered according to company Standards Control Deoartment. Droiect standards. They are recorded and management department, and ' by 'the accounted in speck forms. A conclusion experimental plant technological service. for every waiver is certified by Technical An experimental developmental program Control Department Chief. At the moment for engine components and engine system of engine shipment all single waivers are is developed for controlling engine design considered in combination, as a whole. A development process. This program is list of allowed waivers is certified, agreed upon by scientific organizations and W

7 Technological, measurement and testing waivers list. Before accepting an engine, equipment are subject to control. NPO this list is considered and certified by Energomash standards provide an order of engine components designers. NPO controlling procedures. Energomash's Quality Control Service accounts and analysis waivers in engine When the ground development is system and parts. completed, the engine quality is controlled in "interagencies" tests. A special Potential Applications commission estimates results of the testings and certifies them with a special The RD-170 is a mature fully developed statement. Each specimen quality is engine. It provides the opportunity to controlled by a fire test (product develop a high performance new booster acceptance test). Periodically (annually) stage without the high cost and long lead engine manufacturing stability and existing time of developing a new engine. A engine design margins are checked out. common booster stage concept powered This procedure is performed in periodical with a single RD-170 engine was analyzed certification tests. After completion of a to determine its applicability to projected ground engine development or a break in vehicle needs. The booster stage defined engine manufacture, qualification tests are is intended to be used as the first stage of carried out. a two stage expendable launch vehicle and also as a liquid rocket booster (LRB) that Qualitv System Control could replace the solid rocket boosters on the Space Shuttle, and also be used on - The quality system is periodically checked. potential early heavy lift launch vehicle. This is performed by a group of NPO Two ELV missions (20k and 50k payloads " Energomash's specialists under an order of to LEO) were used in sizing the common the firm's management. booster stage. The design propellant load for the booster was set by the 50k payload A part with a waiver can be permitted for mission at 800,000 Ibs, approximately further operations, if the waiver does not 90,000 Ibs greater than the propellant load affect the engine quality and reliability. of the Russian common booster used on Such a permission for a waiver is made by the Zenit and Energia vehicles. The two a special permission card. In the missions require different upper stages, permission card are shown a waiver cause, initial thrust settings, and some propellant is a person liable for the waiver, and off loaded for the 20k mission with a measures to be undertaken to prevent from cryogenic upper stage. Figure 7 shows the waiver causes in the future. A card has 2 stage ELV configurations with key marks, which define a job order number, characteristics noted. drawing and part numbers, quantity and others. Permission cards are numbered by For use as strap-on LRB's on the Space a fabricating shop number and job order Shuttle, the propellant load was reduced to number. Cards are kept in a fabricating 720,000 Ibs to optimize payload. The shop. The card form allows copying. delivered payload to 82 NM was 57,000 Ibs, Specialists and managers sign a card. approximately 8,000 Ibs less than the Then it is certified by Design Bureau Chief baseline Space Shuttle capability with and agreed upon by a customer. Then the RSRM's. An early Heavy Lift Configuration card is copied and sent to relevant NPO (External Tank with 3 SSMEs at 104%) Energomash's departments. When was defined and evaluated with different assembling an engine specimen, data for numbers of strap-on common boosters. t/ all waivers are gathered in the allowed

8 Table 4

RD-170 Booster Strap-ons Effect on Early Heavy Lift Vehicle Performance

Configuration Payload (Shuttle ET with 3 SSMES @? 104%) (20 x 185 @ 51.6'7 Wgross millions Ibs TNV Liftoff

2 RD-170 LRB'S 156,000 3.6 1.22

3 RD-170 LRBs 234,000 4.5 I.35

4 RD-170 LRB's 287,000 5.4 1.43

6 RD-170 LRBs'* 388,000 7. I 1.60

"IOO x 100 Circular Parking Orbit

The two strap-on common booster configurations would place 156,000 Ibs in a

20 by 185 mile LEO parking orbit. Table 4 PByI0.0 28k 19.5 X Z1.5k lists the additional payload capability available by adding more strap-on boosters.

Summary 11,101~ }%.*," The RD-170 rocket engine is:

High technology FEZ{s.mD.ar M.

. High performance 1.3 1.3 1.33 . Reusable . Designed for operability . Available now Figure 7 Two-Stage ELV Configurations