The Air Force Research Laboratory (AFRL), NASA’s Space Technology Mission Directorate, and Masten Space Systems Inc. successfully tested a liquid methane rocket engine, the first of its kind tested at AFRL.

The Masten 25k lbf thrust Broadsword rocket engine. (Masten Space Systems photo/Matthew Kuhns)

The M10A Broadsword is a LOX/LCH₄ dual expander cycle engine, with an additively manufactured aluminum thrust chamber assembly. The dual expander cycle offers an ideal cycle in this size range, enabling reusability, optimal closed loop performance, and very cost effective design and production price points, according to NASA.

The use of a dual expander cycle, with both the oxygen and methane heated in the cooling jacket and fed into independent turbopumps, contributes to the lower cost and higher reusability of the engine. Using methane and oxygen in an expander cycle also provides a very benign environment to the turbomachinery.

In an expander cycle, the temperature of the gasses as they pass through the turbine are moderate and do not require any special materials or coatings on the turbine. Also, the gasses are clean and do not leave a soot buildup.

These two facts make the turbomachinery inherently reusable, which lowers operational costs, and since no special materials or coatings are required, the components can be made less expensively.

AFRL and Masten signed a Cooperative Research and Development Agreement in December 2018. The agreement enabled Masten to test the Broadsword 25K engine at AFRL’s rocket testing facility at Edwards Air Force Base in Test Area 1-125 and complete NASA’s Tipping Point contract requirement of a 10-second hot fire test.

The Broadsword 25K engine required a large supply of high-pressure gaseous nitrogen to pressure feed the engine. AFRL’s Aerospace Systems Directorate and their Rocket Propulsion Division at Edwards AFB has the capability at Test Area 1-125 to deliver a large supply of high-pressure gaseous nitrogen.

The hot fire campaign started in July 2019 with four hot fire tests before the final test of 10 seconds of combustion. These hot fire tests validated the tune ignition and start-up transients of the engine. The culmination of testing ended 10 December 2019 when Masten completed the Broadsword 25K engine test of 10 seconds of steady state combustion.

The success of these hot fire tests validated Broadsword’s startup transient and steady state performance with the new technology developed under the Tipping Point program.

Working on the 25K Broadsword Tipping Point has been a wonderful project. The successful hot fire testing paves the way for exciting new high performance rocket engine designs.

—Matthew Kuhns, chief engineer at Masten Space Systems and principle investigator on Tipping Point

The Tipping Point public-private partnership is an innovative way NASA helps industry develop promising space technologies that could benefit future commercial and government missions.

Masten was founded by CTO David Masten in 2004 and is located in Mojave, California. Masten’s main focus is “enabling space transportation and reliable planetary landers for the Earth, Moon, Mars, and beyond. We are a passionate company of inventors, creators and builders with goals that include landing our own vehicle on the moon,” according to the company website.

NASA’s Space Technology Mission Directorate, which invests in and develops transformative space technologies to enable future missions, selected Masten for a Tipping Point award to mature the M10A 25,000 lbf liquid oxygen/methane Broadsword Engine in 2017. NASA Tipping Point contracts are awarded to companies with technologies that are on the verge of maturation and are likely to benefit both NASA and the commercial space market.

The AFRL Rocket Lab at Edwards AFB has played a key role in advancing rocket engine technologies for the nation since 1952. AFRL has been a prominent player in nearly every liquid rocket engine developed and flown by the United States. This testing is a trailblazer for future liquid methane engine tests and partnerships among the commercial rocket industries.