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The Hermes Propulsion system is responsible for boosting the vehicle to Mach 3 and 80,000 ft. The motor is lit by an ignition train at T-0 and burns out around 7 seconds later at 21,000 ft.
Design
Impulse: 7970,110 Ns (93% 73% P)
Propellant: Ocean Water
Average thrust: 10,749 N
Motor designation: P-1074910800
Propellant mass: 64.89 lbs
Delivered ISP (approximate): 274 204 s
Nozzle throat dia: 1.758 in
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