Engine Model: XR3A2. Designer: XCOR. Developed in: 2000-2004. Application: First stages. Propellants: Lox/Alcohol. Thrust(vac): 700 N (150 lbf). Chambers: 1. Country: USA. Status: Hardware. The XR3A2 700-newton engine was the first XCOR LOX/alcohol engine, accumulating 61 brief runs in the course of injector concept development, which led to later engines.