Afterburner (Reheat): An additional combustion component utilized in many supersonic military jet engines to provide a significant, temporary increase in thrust. The system functions by injecting raw fuel directly into the hot exhaust stream of the turbine section, where there is still sufficient unburned oxygen. Because the fuel ignites in the tailpipe rather than the main combustion chamber, it bypasses the temperature limitations of the turbine blades, allowing for a massive expansion of exhaust gases and a substantial increase in exit velocity.
Operational Characteristics
While an afterburner can increase the thrust of a jet engine by 50% or more, it is extremely inefficient in terms of fuel consumption. In some aircraft, engaging the afterburner can increase fuel flow by a factor of three to five, meaning it is typically reserved for critical mission phases such as:
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Takeoff: Specifically for carrier-based aircraft or heavily laden bombers requiring short takeoff rolls.
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Supersonic Interception: Achieving and maintaining speeds above Mach 1 (except in “supercruising” aircraft).
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Combat Maneuvering: Providing the necessary power to recover energy during high-G dogfighting.
Visual and Physical Signatures
The engagement of an afterburner is characterized by a visible “flame” extending from the exhaust nozzle, often accompanied by shock diamonds (or Mach disks)—a pattern of standing waves formed by supersonic exhaust gases. Additionally, it significantly increases the aircraft’s Infrared (IR) signature, making it much easier for heat-seeking missiles to track and lock onto the platform from a distance.