The RBCC, or Rocket-Based Combined Cycle propulsion system, is one of the two types of propulsion systems that may be tested in the Boeing X-43 experimental aircraft. The RBCC, or strutjet as it is sometimes called, is a combination propulsion system that consists of a ramjet, scramjet, and ducted rocket, where all three systems use a shared flow path.
It has been speculated that aerospace engineer Richard Foster originally introduced the term RBCC into the aerospace nomenclature.
A TBCC, or Turbine Based Combined Cycle propulsion system, is a turbine engine combined with a ramjet and scramjet.
A TRCC, or Turbo Rocket Combined Cycle propulsion system, is another combination propulsion system that combines an afterburning turbine engine with a RBCC propulsion system.