Wikipedia says an early requirement asked for a delta-v of 3,100 m/s: https://en.wikipedia.org/wiki/Boeing_X-37#Development https://en.wikipedia.org/wiki/Boein

Wikipedia says an early requirement asked for a delta-v of 3,100 m/s: https://en.wikipedia.org/wiki/Boeing_X-37#Development https://en.wikipedia.org/wiki/Boeing_X-37#Development You can estimate engineering limits from the rocket equation, delta-v = effective exhaust velocity * ln(mass ratio). In orbit, it probably uses hypergolic propellants, likely N2O4 and one of the hydrazines. These have exhaust velocities of about 3,350 m/s in vacuum. So, with the orbiter weighing 4.99 tonnes loaded, you could guestimate figures from 2,300 m/s (50% fuel fraction, payload+orbiter = 2.50 tonnes) up to 7,600 m/s (90% fuel fraction, payload+orbiter = 500 kg, if that's possible or useful). https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation https://en.wikipedia.org/wiki/Liquid_rocket_propellants#Bipropellants https://en.wikipedia.org/wiki/Liquid_rocket_propellants#Bipr... For comparison, the far larger (~100 tonne) space shuttle orbiter can do 300 m/s of delta-v, carrying about 20 tonnes of monomethylhydrazine + N2O4. (Note that's a factor of two lower than what the rocket equation allows; I don't know why that is). https://en.wikipedia.org/wiki/Space_Shuttle_Orbital_Maneuvering_System https://en.wikipedia.org/wiki/Space_Shuttle_Orbital_Maneuver...