Status: Hardware. Date: 2000-2004. Thrust: 220 N (40 lbf).
The XCOR XR3B4 regeneratively cooled engine was capable of 220 newtons thrust, using nitrous oxide and isopropyl alcohol as propellants. This engine had completed 216 runs with a cumulative burn time of more than 812 seconds. XCOR designed this engine for use as a maneuvering thruster on spacecraft.