Aerojet Rocketdyne AR1

The Aerojet Rocketdyne AR1 is an American rocket engine project in the 2,200-kilonewton class (about 500,000 pounds-force of thrust), designed to burn kerosene-grade RP-1 with liquid oxygen in an oxidizer-rich staged combustion cycle. It was conceived in 2014, when Aerojet Rocketdyne argued for an all-new American propulsion system, and it took shape as a possible replacement for the Russian-made RD-180 that powered the Atlas V after Congress required the Air Force to develop a domestic alternative. Dynetics was a development partner supplying parts of the main propulsion system, the ignition system and ground support equipment. The US government funded a prototype from 2016, and by 2018 the Air Force had committed 295 million US dollars while Aerojet put in 86 million of its own. The engine passed its Critical Design Review in May 2017, but in September 2018 United Launch Alliance chose Blue Origin's BE-4 for the first stage of Vulcan, and as of 2019 there were no plans to take the AR1 to full production. In October 2019 Aerojet Rocketdyne agreed to work with Firefly Aerospace on an AR1-powered Beta launcher.