Technicians roll the first fully-assembled BE-4 across the floor at Blue Origin’s facility in Kent, Washington. Source: Blue Origin

Aerospace company Blue Origin recently completed the longest duration test firing yet of its BE-4 rocket engine, according to company founder Jeff Bezos. BE-4 is in development for Blue Origin’s upcoming heavy-lift rocket, but is also being marketed as an American-made replacement for the Russian RD-180.

During the test, the engine fired at 65% of its maximum power for 114 seconds as engineers swept through a range of mixture ratios of the liquid natural gas (methane) fuel and liquid oxygen oxidizer.

Blue Origin is developing BE-4 for its New Glenn launch vehicle, a 270 ft (82 m) tall heavy-lift rocket with 3.85 million pounds (17,100 kN) of thrust that could be used for a range of missions, including satellite launches and eventual crewed trips to space. The rocket’s first stage will be powered by seven BE-4 engines, while its second stage will have one.

The first stage of ULA’s Vulcan rocket could be powered by two BE-4 engines and several solid rocket boosters. Concept image source: ULA

RD-180 Replacement

Blue Origin is also positioning the engine as the quickest way to end American dependence on the RD-180 engine manufactured by Russia. A single RD-180 engine currently powers the first stage of United Launch Alliance’s (ULA) Atlas V rocket. The U.S. government relies on Atlas V – and thus on the Russian-made RD-180 – for a number of national security missions, including military communication and reconnaissance satellites.

ULA’s replacement launch vehicle for Atlas V is called Vulcan. In September 2014, ULA partnered with Blue Origin to develop the BE-4 engine as a replacement for the RD-180 in the new Vulcan rocket. Vulcan will use two BE-4 engines in its first stage if ULA ultimately selects the LNG-fueled engine (Blue Origin’s engine faces competition from the kerosene-fueled AR1 engine in development at Aerojet Rocketdyne). ULA has indicated that it is leaning toward BE-4 for Vulcan but has yet to make its choice.

Engine Development

Blue Origin’s coat of arms. Source: Blue OriginBlue Origin began developing BE-4 in 2011. The first fully-assembled engine was completed in March 2017, and the first brief test firing occurred in October 2017.

The company takes a methodical approach to rocket development. Its coat of arms features an hourglass with wings, two turtles reaching for the heavens and the words “Gradatim Ferociter,” which means “step by step, ferociously.” The images signify that time is fleeting but a slow and steady approach leads to success.

BE-4 is designed for reusability with a minimum design life of 25 launches and landings. Source: Blue OriginBE-4 represents the fourth generation in Blue Origin’s line of rocket engines. The company’s first engine ran on a single propellant (peroxide) and produced just 2,200 lbf (8.9 kN) of thrust at sea level. For BE-2, the company switched to a kerosene/peroxide design that generated 31,000 lbf (140 kN) of thrust. The BE-3 engine that powers Blue Origin’s New Shephard suborbital booster burns liquid hydrogen and liquid oxygen to produce 110,000 lbf (490 kN) of thrust. The company completed its most recent test flight of the New Shephard rocket and crew capsule in December 2017.

At full power, BE-4 is designed to generate 550,000 lbf (2,400 kN) of thrust at sea level. It runs on an oxygen-rich staged combustion cycle in which propellant is burned in multiple stages to increase engine efficiency and power. In this type of engine, a portion of the propellant is first burned to drive a turbopump that pressurizes the propellant entering the main combustion chamber.

Low Cost, Low Risk

The BE-4 engine is being marketed as an American-made replacement for the Russian RD-180, pictured here. Source: NPO Energomash

In marketing the BE-4, Blue Origin emphasizes that the engine’s development costs are fully paid for by the private sector and claims it will save U.S. taxpayers an additional $3 billion in national security launch costs over 20 years by providing higher thrust than the RD-180. The company says this allows greater payload capacity per flight as well as a modified rocket design that leaves out one of the solid rocket boosters normally strapped to the outer hull of the rocket to provide additional thrust at a cost of $10 million per flight.

Blue Origin also asserts the BE-4 is a low risk engine that is designed “to be a moderate performing variant of the high performance oxygen-rich staged combustion cycle architecture.” In other words, the company took a conservative design approach with the BE-4, and doesn’t push the engine’s components to the bleeding edge of the performance envelope. Compared to an RD-180’s 3,700 psi chamber pressure, BE-4 runs at only 1,950 psi. The reduced pressure means that the engine is exposed to lower stress, allowing the engine to achieve its minimum reusability target of 25 missions.

The two rockets that BE-4 is anticipated to power, New Glenn and Vulcan, are not expected to fly for the first time before 2020 at the earliest.