According to Tory Bruno, CEO of United Launch Alliance, Aerojet Rocketdyne with their AR1 engine still has a chance to win battle for contract with its main competitor - Blue origin offering their BE-4 engine.
It is truth that more often we can hear voices, that BE-4 is rather potential winner, as process of the development of this engine is more advanced comparing to AR1 project. Aerojet Rocketdyne started in 2014 and work under BE-4 engine project was initialized in 2011, what gives to Blue Origin three years of advantage.
According to latest interview given by Tory Bruno to Defense Daily on 5th April, Aerojet Rocketdyne still has a chance to win. He confirmed, that Aerojet Rocketdyne has even 2 years delay in AR1 program comparing to Blue Origin, but still ULA has not decided to choose any engine. It is possible, that ULA would like to avoid situation when they will have to choose BE-4 without comparing it to any other construction, without full recognizing both positives and negatives of both constructions. It is worth to remind, that both engines are differing in very fundamental matter - used propellant. BE-4 will be fueled with LNG (liquified natural gas) and LOX. It is innovative solution, giving chance to create more environment friendly rocket (propellant is not toxic), faster and less expensive fueling, and less expensive fuel (LNG is significantly cheaper comparing to RP-1). This construction will be first mass manufactured rocket engine fuel with LNG in the history and also largest LNG rocket engine ever created.
Aerojet Rocketdyne decided during designing process of AR1 for more conventional technology. Engine will be fueled with LOX and Kerosene with oxidizer reached combustion chamber providing lower consumption of Kerosene.
These two factors are determining situation of ULA. From the one side Company can choose innovative solution giving chance for reducing costs of the launches in future but from the other side - ULA can decide to purchase conventional engine which probably will not be as economical in exploitation but basing on proven and reliable technology. It is hard to predict which engine will be adopted but surely chances of Aerojet Rocketdyne has just risen and AR1 should be considered as strong competitor of BE-4