Question: What is the difference between ram jet engines(sr71 blackbird) and scram jet engines(sr 72 darkstar from Top Gun Maverick)

Matthew Gata Esperanca answered on 24 Mar 2025:

Very good question, both engines require a significant Mach number to be able to operate. Ramjets operate by using the aircrafts high speed to compress the air, they slow the air down to subsonic speeds before combustion resulting in them operating efficiently at around Mach 2-4. Scramjets are essentially ramjets that keep the airflow supersonic throughout the whole engine, due to this they operate most efficiently at hypersonic speeds (Mach 5+). Scramjets are a lot more advanced and supersonic combustion like this is an area of active research. So both have different operational Mach ranges and require pairing with other propulsion forms to reach their initial operating speeds.