Program Status of the Pratt & Whitney RL60 Engine J.R. Bullock, M. Popp, J.R. Santiago Pratt & Whitney Space Propulsion P.O. Box 109600 West Palm Beach, Florida 33410-9600 Abstract Introduction Pratt & Whitney’s RL10 engine, in a variety of There are two versions of the RL10 in models, has been the cryogenic powerplant for production at Pratt & Whitney at this time. The high-energy upper stages in US expendable RL10A-4 powers both the single engine version launch vehicles for over thirty years. In and the dual engine version of the Centaur upper preparation for future vehicle upgrades, Pratt & stage for the Lockheed Martin Atlas II, Atlas III Whitney has started the development of a next and Atlas V vehicles. The RL10B-2 powers the generation cryogenic upper stage engine upper stage of both the Delta III and Delta IV providing higher performance while maintaining vehicles, built by Boeing. As of this writing, 492 the same installation envelope as the RL10. The RL10’s have been produced and have an Pratt & Whitney RL60 is an advanced liquid accumulated 636 in-space firings. oxygen/liquid hydrogen (LOX/LH2) expander cycle engine incorporating several key Payloads have continued to grow in mass over technologies to increase performance and the history of expendable vehicles, both because operability while maintaining RL10 reignition of need and because of improved vehicle capability, life and reliability. capability. The new expendable vehicles have been developed to offer increased payload Engine performance is characterized by a thrust capability at lower launch costs, while range of 40 to 60 k-lbf, with a 10% growth incorporating improvements in reliability and margin, and a specific impulse of 465 seconds. safety. In concert with these vehicle In order to meet the 60 k-lbf thrust requirement, developments, Pratt & Whitney has established a the engine must be operated at much higher plan for development of a next generation chamber pressures than any current expander cryogenic upper stage engine providing higher cycle. This is made possible by the use of a performance while maintaining the same copper tubular combustion chamber liner, a high installation envelope as the RL10. heat load chamber technology specifically developed by Pratt & Whitney for expander The Pratt & Whitney RL60 is an advanced liquid cycle application. oxygen/liquid hydrogen (LOX/LH2) expander cycle engine incorporating several key The first phase of engine development, the RL60 components and technologies to increase demonstrator engine program, is currently under performance and operability. The RL60 way and will demonstrate technology readiness development program will combine existing for a reduced risk full scale development technologies with new technologies either program. The RL60 engine design is defined, developed under Integrated High Payoff Rocket critical design review was passed for the Propulsion Technology (IHPRPT) programs with demonstrator engine in the first quarter of 2002, the US Air Force or independently by Pratt & and the engine program is on plan to conduct full Whitney. It will include components designed power engine tests in 2003. The RL60 and developed specifically for the RL60 by demonstrator phase is approved and fully funded rocket engine propulsion companies outside the by Pratt & Whitney and will serve as a basis for United States. It is being developed to cover a full scale RL60 engine development. broad range of thrust requirements, designed to Furthermore the RL60 demonstrator engine will operate at any thrust setting between 40,000 lbf be available as a testbed for future Air Force and to 65,000 lbf, thus covering a range of potential NASA technology programs. vehicle requirements. Figure 1 shows an 1 overview of existing and planned cryogenic Program Overview upper stage engines including the RL10 and RL60. The RL60 Demonstrator Engine Program is the first phase in development of the RL60 Based on the excellent track record of the RL10 Cryogenic Upper Stage Engine. This program is expander cycle engine, this cycle was selected funded by Pratt & Whitney. Its goal is to for RL60. The expander cycle is inherently safe demonstrate the major components of the RL60 because of its self-limiting power cycle. as a system in full scale at the 60,000 lbf Additionally, because it uses no external operating condition. combustion devices to drive turbomachinery, it is the best approach for in-space re-starts. The This program has its beginnings in the original basic architecture of the RL60 also draws from commercial Cryogenic Advanced Upper Stage studies conducted and lessons learned during the Engine (cCAUSE) program of 1999. This Upper Stage Demonstrator (USD) program, program became the RL50 Engine Program, so awarded to P&W by the Air Force Research designated to identify its 50,000 lbf thrust class Laboratory as part of the IHPRPT initiative. The (ref. 2). During the latter half of 1999 and early USD program encompassed cycle balance and 2000, Pratt & Whitney and Snecma established a component performance trade studies, plan to develop a new cryogenic upper stage component and system design and integration engine that encompassed the requirements and activities, and component testing intended to capabilities of both the RL50 and the Vinci. It lead up to a demonstrator engine. This program was thought that effective cost management and helped identify and/or reinforce the need for economies of scale could be achieved by critical technologies and components, and developing one engine to meet the future needs provided pathfinders for fabrication of US and European expendable launch vehicles. technologies. The USD program also provided a This engine was given the designation key piece of information for an advanced SPW2000, signifying the partnership and the expander engine, namely a test of a full-scale new millennium. Unfortunately, it was not a copper tubular combustion chamber (described program fully embraced by ESA, and was in ref. 1) discontinued in June 2000. Since that event, Pratt & Whitney has re-established its own program, Existing 470 Development now designated the RL60 to identify its design RL60 RL60 465 thrust level. The RL60 Demonstrator Program RL10B-2 MB60 VINCI 180 was initiated at the end of 2000. Fig. 2 provides 460 an overall RL60 program schedule, including the Current Engines 455 cCause, RL50 and SPW2000 efforts preceding RL10A-4-1 RD-0146 (CADB) LE-5A (Japan) the RL60. Specific Impulse - sec 450 LE-5B (Japan) 2X RL10A-4-2 DEC HM7 B (Snecma) 445 Activities: 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Program Development YF-75 (China) cCause Program Planning RL50 Authorization RL50 Development Planning 440 SPW2000 MOU SPW2000 Feasibility Studies 0 10000 20000 30000 40000 50000 60000 70000 ESA Board Decision Thrust - LBs RL60 Business Case Studies Nov 8 Figure 1: Existing and Planned Cryogenic Passport 0 Review Engine Demonstration Upper Stage Engines Design Hardware Fabrication/Assembly Demo Engine Engine Demonstration Test to Test The market for expendable launch vehicles has Full-Scale Development Vehicle Integration not met the predictions made just a few short Design Hardware Fabrication/Assembly First Engine to Test Development Testing years ago. The date envisioned for first launch of Qualification Testing Certification a next generation high energy upper stage engine Production has continued to move to the right. For this Production Engine Deliveries reason the RL60 Development Program has been divided into two parts. The first part, and the Figure 2: RL60 Program Schedule subject of this paper, is the RL60 Demonstrator Engine Program. Following the successful completion of this phase, and the establishment The RL60 Demonstrator Engine incorporates all of launch vehicle commitment, the RL60 Full the design requirements of the full scale Scale Development (FSD) Program will be development engine. However, the Demonstrator initiated. Program will concentrate solely on the “core” 2 components. The RL60 Demonstrator will In order to take advantage of technologies and include the combustion chamber, injector, capabilities throughout the industry, the RL60 regeneratively cooled nozzle and both main includes components designed and fabricated by propellant turbopumps. It will include the highly key non US space propulsion partners. IHI, the reliable RL10 dual direct spark ignition system center of excellence for rocket engine and flight-type thrust control valves. Plumbing turbomachinery in Japan is designing and and on/off valves will be rig type hardware building the main fuel turbopump. CADB of designed to flight-type operational and Russia is responsible for the main LOX performance requirements. The RL60 turbopump. And Volvo Aero of Sweden is Demonstrator will not include the propellant providing the regeneratively cooled (regen) boost pumps or the radiation cooled extendable nozzle incorporating their laser welded sandwich nozzle and its deployment system. technology. Pratt & Whitney is responsible for system design and integration, engine controls Although the Demonstrator Engine does not and combustion devices. include all the components of the full scale development engine, it is being designed with The RL60 Demonstrator Program is well attention to flight-type requirements. Even where underway and has passed its Critical Design program limitations forced the use of less- Review. Hardware is in fabrication and the stringent requirements, the status of the engine majority