AKA: Multi-Use Thruster. Status: Developed 2005. Date: 2005. Thrust: 5.64 kN (1,267 lbf). Unfuelled mass: 2.00 kg (4.40 lb). Specific impulse: 292 s. Height: 0.22 m (0.71 ft). Diameter: 0.12 m (0.39 ft).
New technology motor with a quantum leap in thrust/weight ratio and use of mixed oxides of nitrogen (MON) oxidizer which has a much lower freezing point than standard nitrogen tetroxide (MON-25, 75% N2O4 and 25% nitric acid, had a freezing point of -50 deg C versus -12 deg C for N2O4 alone). The engine has a thrust to weight of 290, compared to 40 for the Marquardt R-40A in the same class. A key development problem was getting MON-25 to burn without catastrophic combustion instability. The engine uses a fuel-rich mixture ratio and is film and radiatively cooled. The engine can be throttle from 50 to 115% of design thrust. The engine also had excellent ramp-up and minimum pulse characteristics, important for military applications. A version of the motor using a composite nozzle and thrust chamber was built, demonstrating a T/W ratio of 600, but it was found to be too fragile for typical applications.
Throttled thrust(vac): 250.000 kN (56,200 lbf). Engine: 2.00 kg (4.40 lb). Chamber Pressure: 34.00 bar. Area Ratio: 12. Propellant Formulation: MON-25/MMH. Thrust to Weight Ratio: 290. Restarts: 1000.