Everyday Astronaut & the RL 10 Engine

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It’s not everyday that you get to explore rocket engines with Everyday Astronaut. He does incredible deep dives into many rocketry topics, but has a special love for engines: everydayastronaut.com

UPDATE: the fun video is now up.

We traced all of the LOX and Hydrogen lines around my Pratt & Whitney RL-10 like a couple of excited children. First developed in 1959, the Pratt & Whitney RL 10 was the first hydrogen/oxygen engine, and it still flies today as the upper stage for ULA rockets.

It has carried spacecraft the moon and the sun and every planet in our solar system and beyond. In 1959, hydrogen was considered a dangerous and unpredictable fuel, and little of it was available for research. “It was our trip to Florida to see the RL10 firing that gave me confidence to use hydrogen for Apollo.” — Werner Von Braun in the book Advanced Engine Development at Pratt & Whitney

The bell is composed of 360 pipes that route the super-chilled hydrogen fuel down and back before combustion to keep the nozzle from melting (regenerative cooling). They are brazed together with pure silver on a bell-shaped mandrel.

This engine uses a clever expander cycle with gear-coupled fuel and oxidizer turbo pumps, a design that has not been used on any other hydrogen engine. The phase change of the hydrogen fuel powers both the fuel and oxidizer cyro pumps.

A Pratt & Whitney employee claimed that this unit was the second one built. It may be the only original RL10 in private circulation. More details below. Part of the Future Ventures’ 🚀 Space Collection.

2 responses to “Everyday Astronaut & the RL 10 Engine”

jurvetson

Jun 11, 2021 at 12:13 am

He gave a nice shout out from his visitExpander Cycle Diagram. Heat from combustion powers the fuel and oxidizer pumps.

“In an expander cycle, the fuel is heated before it is combusted, usually with waste heat from the main combustion chamber. As the liquid fuel passes through coolant passages in the walls of the combustion chamber, it undergoes a phase change into a gaseous state. The fuel in the gaseous state expands through a turbine using the pressure differential from the supply pressure to the ambient exhaust pressure to initiate turbopump rotation. This can provide a bootstrap starting capability as is used on the Pratt & Whitney RL10 engine. This bootstrap power is used to drive turbines that drive the fuel and oxidizer pumps increasing the propellant pressures and flows to the rocket engine thrust chamber. After leaving the turbine(s), the fuel is then injected with the oxidizer into the combustion chamber and burned to produce thrust for the vehicle.”

Here is the detailed propellant flow schematic from the Pratt & Whitney RL10A-3 Design Report (dated Feb 28, 1966):
It burns blue. Here’s a 2009 NASA experiment with the Common Extensible Cryogenic Engine (CECE) at full throttle (video ): This RL10 engine is fuelled by a mixture of -182.8° Celsius liquid oxygen and -252.8° Celsius liquid hydrogen. The engine components are super-cooled to similar low temperatures. As CECE burns its frigid fuels, gas composed of hot steam is produced and propelled out the nozzle creating thrust. The steam is cooled by the cold engine nozzle, condensing and eventually freezing at the nozzle exit to form icicles.

And a pair I saw in the field, from an ICBM

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Tesla Oracle

Nov 13, 2021 at 9:04 am

Thanks Steve for the valuable insights for learning and the pics. 👍

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Everyday Astronaut & the RL 10 Engine

2 responses to “Everyday Astronaut & the RL 10 Engine”

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