Engine Model: Transtar. Designer: Aerojet. Propellants: N2O4/MMH. Thrust(vac): 16.700 kN (3,754 lbf). Isp: 328 sec. Mass Engine: 76 kg (167 lb). Length: 1.27 m (4.16 ft). Chambers: 1. Chamber Pressure: 23.80 bar. Area Ratio: 132.00. Thrust to Weight Ratio: 22.36. Country: USA. Status: Development completed 1987. The Transtar system was an upper stage engine using injector(s), chamber, and nozzle derived from the OMS system. These propellants are pump-fed which increase chamber pressure and Isp. They also permit the use of low-pressure lightweight tanks.. Manufacturer: AeroJet Propulsion Division. Applications: upper stage. Mounting: gimballed ( 10 degrees by two electromechanical actuators. Mixture Ratio: 1.8:1. Cooling Method: fuel regenerative for chamber, radiative for extension. Burn Time: not available, 15 starts.