Jeff Bezos isn’t the only person interested in vintage NASA technology. Public and private entities alike are actively taking a second look at the Rocketdyne F-1 engines that helped notch Saturn V rockets as the tallest, heaviest and most powerful rocket ever operated — even today, 40 years after the demise of the Apollo program.
All 13 Saturn V multistage launch vehicles that left Earth’s atmosphere between 1967 and 1973 sat atop five F-1 engines that constituted the first stage booster. Each engine measured 6m tall by 4m wide and produced a staggering 680,000kg of thrust (and temperatures nearing 3300C) over its roughly two minute specific impulse. The F-1 ran on RP-1 rocket fuel, a highly-refined form of kerosene that is cheaper and safer than liquid hydrogen fuels, with a liquid oxygen oxidizing agent.
Incredibly, the engine was entirely mechanical and lacked any form of electronic or software control — similar to automobile engines of the day, just with 55,000HP. The Thrust Chamber, the rocket equivalent of an engine cylinder, burned 1565 litres of RP-1 mixed with 980kg of liquid oxygen every second from the fuel turbopump and manifold assembly at the top of the rocket. Below the thrust chamber, the rapidly burning fuel was directed through the nozzle extension, pushing the entire launch vehicle in the opposite direction at 10,000km/h.
The engine’s second iteration, the F-1A produced an even 900,000kg of thrust while significantly reducing its weight. Unfortunately, the F-1A never made it into flight testing as the F-1 program was mothballed at the close of the Apollo program in favour of the more-powerful (and more-expensive) solid state boosters used in the Space Shuttle program.
But nearly half a century later, the venerable F-1 is being pulled out of storage by NASA and the Pratt & Whitney Rocketdyne (PWR) company with hopes that it can inspire a new generation of rockets for use in the Advanced Booster Competition, which aims to build the best, most affordable, reliable heavy-lift rocket possible for the upcoming Space Launch System. NASA has accepted a total of six proposals for the competition, whose winners will be awarded the construction contracts since NASA no longer builds its own hardware.
“The initial SLS heavy-lift rocket begins with the proven hardware, technology and capabilities we have today and will evolve over time to a more capable launch vehicle through competitive opportunities,” William Gerstenmaier, associate administrator for the Human Exploration Operations Mission Directorate at NASA Headquarters in Washington, said in a press statement.
As such, researchers Marshall Space Flight centre (MSFC) recently began disassembling and inspecting one of these classic engines — serial number F-6049, which had previously been in storage at the Smithsonian — in an effort to understand precisely how it worked. See, since each engine was built by hand, in a series of iterations — fabricate a part, test it, modify, and repeat until satisfied — under truly monumental deadlines demanded by President Kennedy, and without the aid of any sort of computer drafting, none of the 65 F-1 engines quite match the original design specs. Each has its own idiosyncrasies and quirks. But by refurbishing and test firing the engine using modern data-capture methods, including structured light 3D scanning techniques, rocket scientists can establish baseline attributes for the engine series as well as detailed system schematics, both of which can be used as the basis to build the next generation of rockets.
“Modern instruments, testing and analysis improvements learned over [the past] 40 years, and digital scanning and imagery techniques are allowing us to obtain baseline data on performance and combustion stability,” MSFC systems engineer Nick Case told Space.com. “We are even gathering data not collected when the engine was tested originally in the 1960s.”
In a 20-second “hot fire” test in January, the MSFC researchers mounted the a pair of F-1 gas generators — the part of the engine that drives the fuel and oxidizer pumps — on a test bed and lit them up. Each generator produced 14,000kg of force and a very impressive plume of flames.
NASA shared this captured data with one of its industry partners, PWR. The company has started further restoration efforts on the engine components with an eye for improvement and eventually, the debut of the F-1B. This new iteration will produce 816,000kg of thrust without the overly complicated mechanical aspects of its predecessors. These improvements include a simplified turbopump and exhaust duct, as well as nozzle design and combustion chamber modifications.
“One major difference that most people would notice right away is that… we’ve decided to do away with that turbine exhaust that feeds into the nozzle, and that part of the nozzle that comes after where the turbine exhaust manifold would dump in,” Kim Doring, Dynetics space launch systems program manager, told Ars Technica “So the chamber nozzle would be smaller-would look smaller even to the common person, even though it’s still huge. That specifically will save a lot of money and complexity in the way we’re deciding to build the engine to address NASA’s specific goals of affordability and performance.”
PWR has precious little time until the 2015 competition deadline, and is up against stiff competition, both of the liquid and solid fuel varieties. But no matter which company wins, so too does science.