Scramjet aircraft. Computer artwork of an aircraft powered by a scramjet jet engine. The scramjet is a variant of the ramjet that was built in the 1950s and 60s. The ramjet, or stovepipe jet, was invented in 1913 but not produced until the 1940s. It does not have an internal compressor, but uses the engine's forward motion to compress incoming air. This means it cannot move an object from a standstill. In scramjets the combustion occurs in supersonic airflow - again relying on high speed to compress the air before combustion.