👉 A scramjet is a ramjet with supersonic combustion. In ordinary ramjets, the air is decelerated to subsonic velocities before combustion, but this is not
the case in a scramjet.
👉 Ramjets have a velocity range of 1 to 6 Mach in theory, but Scramjets have a range of 12 to 24 Mach in theory.
👉 Ramjets and scramjets can’t produce thrust at zero velocity, they need a lot of airflow to start.
👉 Scramjets have a higher specific impulse than Ramjet.
👉Owing to subsonic combustion, Ramjet has greater efficiency and
operability than Scramjet, which has a lesser efficiency due to supersonic combustion.