Author Topic: RL-10 Rocket Engine Progress Report  (Read 272 times)

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RL-10 Rocket Engine Progress Report
« on: 11/07/2017 02:13 AM »
"RL-10 Rocket Engine Progress Report No. 11"

Jeff Quitney
Published on Nov 6, 2017

Atlas-Centaur fourth flight on 11 December 1964.

Contractor's progress report film for the Centaur upper stage's RL-10 liquid hydrogen-fueled rocket engine manufactured by Pratt & Whitney Aircraft. Includes the Atlas-Centaur 4th launch on Dec 12. Unfortunately, the sound is missing on this film.

The RL10 is a liquid-fuel cryogenic rocket engine used on the Centaur, S-IV, and Delta Cryogenic Second Stage 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 (14,54524,729 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.

The engine produces a specific impulse (Isp) of 373 to 470 s (3.664.61 km/s) in a vacuum and has a mass ranging from 131 to 317 kg (289699 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.


The RL10 was first tested on the ground in 1959, at Pratt & 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.


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 May 4, 1999, Delta III launch carrying the Orion-3 communications satellite.

Aerojet Rocketdyne is working toward incorporating additive manufacturing into the RL10 construction process. The company conducted full-scale, hot-fire tests on an engine with a printed core main injector in March 2016, and on an engine with a printed thrust chamber assembly in April 2017.

Centaur is a rocket stage designed for use as the upper stage of space launch vehicles and is currently used in the Atlas V. Centaur was the world's first high-energy upper stage, burning liquid hydrogen (LH2) and liquid oxygen (LOX), and has enabled the launch of some of NASA's most important scientific missions over its 50-year history.

Centaur was the brainchild of Karel J. "Charlie" Bossart (the man behind the Atlas ICBM) and Dr. Krafft A. Ehricke, both Convair employees. Their design was essentially a smaller version of the Atlas, with its concept of using lightweight "stainless steel balloon" tanks whose structural rigidity was provided solely by the pressure of the propellants within...

Centaur is powered by one or two RL10 rocket engines.

The Atlas-Centaur was an American expendable launch system derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station in Florida.

AC-4 (December 11) reached orbit successfully, but could not be restarted due to an ill-conceived design modification--the ullage rockets were reduced in size to save weight, however, they proved insufficient to settle the propellants in the tanks. Venting liquid hydrogen caused the Centaur to tumble out of control.

Originally a public domain film from the US Air Force slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

« Last Edit: 11/07/2017 02:36 AM by Galactic Penguin SST »
Tony De La Rosa