First flight 1962 (RL10A-1) Application Upper stage engine | Designer Pratt & Whitney/MSFC | |
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Country of origin United States of America Manufacturer Pratt & Whitney Space Propulsion
Pratt & Whitney Rocketdyne
Aerojet Rocketdyne Associated L/V Atlas
Titan
Delta IV
Saturn I | ||
The RL10 is a liquid-fuel cryogenic rocket engine used on the Centaur, S-IV and DCSS upper stages. Built in the United States by Aerojet Rocketdyne (formerly by Pratt & Whitney Rocketdyne), the RL10 burns cryogenic liquid hydrogen and liquid oxygen propellants, with each engine producing 64.7 to 110 kN (14,545–24,729 lbf) of thrust in vacuum depending on the version in use. The RL10 was the first liquid hydrogen rocket engine to be built in the United States, and development of the engine by Marshall Space Flight Center and Pratt & Whitney began in the 1950s, with the first flight occurring in 1961. Several versions of the engine have been flown, with two, the RL10A-4-2 and the RL10B-2, still being produced and flown on the Atlas V and Delta IV.
Contents
- History
- Improvements
- Applications for the RL10
- Common Extensible Cryogenic Engine
- Advanced Common Evolved Stage
- NextGen Propulsion Study
- SLS Exploration Upper Stage
- Original RL10
- Current design
- Engines on display
- References
The engine produces a specific impulse (Isp) of 373 to 470 s (3.66–4.61 km/s) in a vacuum and has a mass ranging from 131 to 317 kg (289–699 lb) (depending on version). Six RL10A-3 engines were used in the S-IV second stage of the Saturn I rocket, one or two RL10 engines are used in the Centaur upper stages of Atlas and Titan rockets and one RL10B-2 is used in the upper stage of Delta IV rockets.
History
The RL10 was first tested on the ground in 1959, at Pratt and Whitney's Florida Research and Development Center in West Palm Beach, Florida. It was first flown in 1962 in an unsuccessful suborbital test; the first successful flight took place on November 27, 1963. For that launch, two RL10A-3 engines powered the Centaur upper stage of an Atlas launch vehicle. The launch was used to conduct a heavily instrumented performance and structural integrity test of the vehicle. The RL10 was designed for the USAF from the beginning as a throttleable motor for the Lunex lunar lander, finally putting this capability to use twenty years later in the DC-X VTOL vehicle.
Improvements
The RL10 has been upgraded over the years. One current model, the RL10B-2, powers the Delta IV second stage. It has been significantly modified from the original RL10 to improve performance. Some of the enhancements include an extendable nozzle and electro-mechanical gimbaling for reduced weight and increased reliability. Current specific impulse is 464 seconds (4.55 km/s).
A flaw in the brazing of an RL10B-2 combustion chamber was identified as the cause of failure for the May 4, 1999, Delta III launch carrying the Orion-3 communications satellite.
Applications for the RL10
Four modified RL10A-5 engines, all of them with the ability to be throttled, were used in the McDonnell Douglas DC-X.
The DIRECT version 3.0 proposal to replace Ares I and Ares V with a family of rockets sharing a common core stage, recommends the RL10 for the second stage of their proposed J-246 and J-247 launch vehicles. Up to seven (7) RL10 engines would be used in the proposed Jupiter Upper Stage, serving an equivalent role to the Ares V Earth Departure Stage.
Common Extensible Cryogenic Engine
The Common Extensible Cryogenic Engine (CECE) is a testbed to develop RL10 engines that throttle well. NASA has contracted with Pratt & Whitney Rocketdyne to develop the CECE demonstrator engine. In 2007 its operability (with some "chugging") was demonstrated at 11-to-1 throttle ratios. In 2009 NASA reported successfully throttling from 104 percent thrust to eight percent thrust, a record for an engine of this type. Chugging was eliminated by injector and propellant feed system modifications that control the pressure, temperature and flow of propellants.
Advanced Common Evolved Stage
As of 2009, an enhanced version of the RL10 rocket engine was proposed to power the upper-stage versions of the Advanced Common Evolved Stage (ACES), a long-duration, low-boiloff extension of existing ULA Centaur and Delta Cryogenic Second Stage (DCSS) technology. Long-duration ACES technology is explicitly designed to support geosynchronous, cislunar, and interplanetary missions as well as provide in-space propellant depots in LEO or at L2 that could be used as way-stations for other rockets to stop and refuel on the way to beyond-LEO or interplanetary missions. Additional missions could include the provision of the high-energy technical capacity for the cleanup of space debris.
NextGen Propulsion Study
NASA is partnering with the US Air Force (USAF) to study next-generation upper stage propulsion, formalizing the agencies joint interests in a new upper stage engine to replace the venerable Aerojet Rocketdyne RL10.
"We know the list price on an RL10. If you look at cost over time, a very large portion of the unit cost of the EELVs is attributable to the propulsion systems, and the RL10 is a very old engine, and there's a lot of craftwork associated with its manufacture," says Dale Thomas, associate director of technical issues at NASA Marshall. "That's what this study will figure out, is it worthwhile to build an RL10 replacement?"
USAF hopes to replace the Rocketdyne RL10 engines used on the upper stage of both the Lockheed Martin Atlas V and the Boeing Delta IV, known as evolved expendable launch vehicles (EELV) that are the primary method of putting US satellites into space. While NASA frequently uses EELVs to launch large scientific payloads, the programme's administration is largely run through other channels.
SLS Exploration Upper Stage
In April 2016 it was reported NASA has chosen to use a design based on four RL10 engines for the Exploration Upper Stage to be used beginning with the crewed EM-2 mission of the Space Launch System.
Original RL10
Current design
The other current model, the RL10A-4-2, is the engine used on Centaur upper stage for Atlas V.