Master of Arts
Date of Defense
Dr. Peter Acsay
Dr. Daniel Rust
Dr. Carlos Schwantes
With the beginning of powered, manned flight, the piston engine drove a propeller or multiple propellers to provide the thrust for lift required to overcome the forces of drag and gravity for flight. As aircraft speeds gradually increased over time, the power needed to overcome the aerodynamic inefficiencies of the propeller to greater speeds and altitudes were quickly realized as a hindrance to the potential of aircraft. With the turbojet engine, this new mechanism and subsequent aerodynamic changes revolutionized aircraft to increased speeds and altitude never before achievable with a piston engine. The United States, after acquiring further and more extensive turbojet engine knowledge from the British during World War II, steadily developed the technology. In a relatively brief amount of time, the turbojet was able to power aircraft reliably beyond the speed of sound.
The General Electric axial flow J79 turbojet engine generated a lasting technological innovation with the first use of production ready variable incidence stator vanes that allowed jet engines to begin to overcome compressor stall. Compressor stall can occur as air flows through the jet engines various air compressing guide and stator vanes with low air pressure building just behind a given blade. The low pressure air cell can cause damaged vanes; build to the point of causing a rotational stall which critically impedes the rotation of the engine, can migrate to the combustion chamber starving the fuel of oxygen needed for ignition, or cause the complete reversal of air flow within the engine. These events can cause minor to catastrophic engine damage or even complete engine failure. Variable incidence stator vanes were no longer static but were adjustable to allow the optimum angle of airflow around the various vanes and thus controlled the compressibility of the airflow through the engine reducing the likelihood of stalls. The use of the this variable stator design within the J79 turbojet allowed the engine to be smaller in diameter, removed complexity, and weighed considerably less than other competing turbojet engines of the time, laying the groundwork for a production run of over thirty years and speeds exceeding Mach 2, or twice the speed of sound.
The purpose of this study is to analyze the General Electric J79 Turbojet engine as it relates to its contemporary turbojet engines, the aircraft it powered, and the effects for General Electric and the military powerplant industry. Additionally, the purpose of this study is to illustrate how the engine helped assist aircraft designers and their companies to satisfy Armed Forces proposals for increased speeds, payloads, systems and the missions to meet a national philosophy of deterrence of a newly perceived threat during the Cold War with the Soviet Union and her Warsaw Bloc allies.
Brimer, Matt C., "Designing Simplicity to Achieve Technological Improvement: The General Electric J79 Turbojet Engine; Innovations, Achievements and Effects" (2017). Theses. 307.