Pratt & Whitney, Rocketdyne To Resurrect 40 Year Old 6,000kN F-1 Engines For SLS Boosters

By: Zach Rosenberg
Source: Flight International

Pratt & Whitney Rocketdyne and Dynetics have announced a resurrected F-1 engine as their entry into the advanced booster engineering demonstration and/or risk reduction (ABEDRR) programme, a precursor to selecting advanced boosters for the Space Launch System (SLS).

The liquid oxygen/kerosene-burning, gas-generator cycle engine produces more than 6,600kN (1.5 million lb) of thrust. Five such engines comprised the first stage of the Saturn V rocket, which launched the Apollo series of lunar exploration missions.

Development could cost half that of a clean-sheet booster design, says John Vilja, vice president of strategy at Rocketdyne. "Now that we have a design that has actually been proven, it's easier to just copy that."

Resurrection of the F-1, the most powerful engine built by a United States company (only the Russian RD-170 is slightly more powerful) has long been a topic of wistful discussion amongst rocketry circles.

"Every rocket designer that's ever come to us says, 'Boy, I wish we had an F-1,' because it solves a lot of problems," says John Vilja, vice president of strategy at Rocketdyne. "It's big thrust in a small space - relatively small."

The F-1 proposal will be submitted as a competitor to a NASA risk reduction contract. Selections, expected in October 2012, will be awarded to several companies. After further development and experimentation, NASA will down-select to a single booster for full-scale development.

Testing in the first phase will involve assembling a power pack, consisting of a complete gas generator and turbopump, for testing. Initially, testing may use leftover hardware from the F-1A programme, a 8,000kN-thrust variant of the engine that was built but never flown. The equipment is now around 40 years old.

"We have three of those that we're tearing apart right now, looking to see where we had galvanic corrosion, figuring out where we might have some things we want to change," says Vilja.

Rocketdyne believes a working powerpack can be assembled and tested by 2015, with additional parts under construction. If NASA selects the F-1 to become the SLS booster, The company believes it can assemble and test a full engine by 2017, and certify it for flight in 2020, in advance of SLS's planned 2021 flight.

The company took the same approach when it was tapped to build the SLS upper stage, the J-2X that is currently undergoing testing. The J-2X is an updated version of the J-2, which flew as the Saturn V's upper stage.

Competitors include Aerojet with the LOX/RP-1 AJ-1000, a significantly scaled-up version of its AJ-26 engine, and ATK's advanced solid rocket boosters.