The Power and Use of Jet Afterburners

As a youngster, I was captivated by cartoons like GI Joe, especially when the Skystriker jet, inspired by the iconic F-14 Tomcat, needed a speed boost. Flames would erupt from its exhaust in these high-intensity scenes, a sight that never failed to excite me. My own sketches of fighter jets always included these fiery exhausts, symbolizing their speed and power. I later learned that these flames were the visual hallmark of Afterburners, an actual component that significantly enhanced a jet’s speed and power.

Additionally, the iconic movie Top Gun is etched in my memory, particularly the scenes where afterburners were fired up to maximum power, enabling the fighter jets to launch off the aircraft carrier.

Jet afterburners, also referred to as ‘reheat’ in British English, form a crucial part of some jet engines, notably those employed in military supersonic aircraft. These afterburners have three primary functions: augmenting thrust for supersonic flight, takeoff, and combat scenarios.

I hope to provide you some information on how an afterburner functions, the history of its development, and its various applications.

The Mechanism of Afterburners

Afterburners work on the principle of adding additional fuel into a combustor in the jet pipe located behind the turbine, thereby reheating the exhaust gas. The use of an afterburner significantly enhances thrust, making it a viable alternative to employing a larger engine. This process dramatically increases fuel consumption, limiting its use to short durations.

Jet engines operate ‘wet’ when the afterburner is in use and ‘dry’ when it isn’t. When an engine is producing maximum thrust in a wet condition, it is at maximum power. In contrast, an engine producing maximum thrust in a dry state is at military power. In essence, afterburners provide the engine with an instant power boost, especially useful in scenarios requiring quick acceleration.

The Evolution of Afterburners

The history of afterburners dates back to the early 1940s, with the first successful application carried out by Secondo Campini on the Caproni Campini C.C.2 aircraft in 1941. Following this, in the late 1940s, American research led to the installation of afterburners on early straight-wing jets such as the Pirate, Starfire, and Scorpion.

The 1950s witnessed the development of several large afterburning engines, like the Orenda Iroquois, the British de Havilland Gyron, and the Rolls-Royce Avon RB.146 variants. Subsequently, afterburners have primarily been associated with military aircraft, establishing themselves as a standard component of fighter aircraft.

The Applications of Afterburners

The application of afterburners is primarily in military supersonic aircraft. However, a select few civilian planes, such as the NASA research aircraft, the Tupolev Tu-144, Concorde, and the White Knight of Scaled Composites, have also employed them. Concorde, for instance, used afterburners during takeoff and to minimize time spent in the high-drag transonic flight regime. In scenarios where supersonic flight is achieved without afterburners, the term ‘supercruise’ is used.

Fighters belonging to the fifth generation, including the F-22 Raptor and Sukhoi Su-57, along with several fourth-generation aircraft like the Eurofighter Typhoon, Saab JAS39 Gripen E, and Dassault Rafale, have the capability to ‘supercruise’.

Despite their power-boosting capabilities, due to their high fuel consumption, afterburners are typically used for short durations. These include heavy-weight or short runway take-offs, assisting catapult launches from aircraft carriers, and during air combat scenarios.

Jet afterburners represent a significant achievement in the field of aerospace engineering, providing an immediate power boost to aircraft when needed most. While their high fuel consumption limits their continuous use, they’ve proven invaluable in certain military and civil aviation applications, contributing significantly to the flexibility and capabilities of modern aircraft.