Key Takeaways

• By injecting additional fuel into the exhaust stream, an afterburner harnesses the residual oxygen to combust, raising exhaust temperature and expansion.
• This simple addition can increase a jet’s thrust by 50 % or more, delivering a significant performance lift without major weight or complexity penalties.
• Its chief drawback is extreme fuel consumption, limiting practical use to short bursts such as carrier take‑offs or high‑speed combat maneuvers.

A jet engine operates on the same fundamental principle as a rocket: mass is expelled forward, generating a reactive thrust in the opposite direction. The engine draws in atmospheric air, compresses it, mixes it with kerosene‑based fuel, and ignites the mixture. The hot gases expand rapidly and exit the rear, producing thrust.

Modern turbofans employ a turbine that recycles energy from the exhaust to spin the compressor, enhancing efficiency, especially at lower speeds. The compressor’s high‑pressure air is then fed into the combustion chamber where fuel is injected.

Even after the primary combustion, the exhaust still contains a significant amount of oxygen. An afterburner takes advantage of this by introducing a secondary fuel stream directly into the exhaust and igniting it. The resulting combustion further heats and expands the gases, pushing the exhaust through a variable‑area nozzle and boosting thrust.

Structurally, an afterburner consists of a set of high‑pressure fuel injectors, a short combustion tube, a flame holder, and an adjustable nozzle. The nozzle must be capable of expanding when the afterburner is off and contracting when it is on to maintain optimal exhaust flow.

Because the additional fuel burn is highly inefficient, afterburners are reserved for scenarios demanding maximum thrust for a brief period—such as short‑runway take‑offs from aircraft carriers or rapid acceleration during aerial combat.

Below is an illustration of an afterburner‑equipped engine from an F‑4 Phantom, sourced from the Virginia Air and Space Museum:

[Engine block diagram showing compressor, combustor, turbine, and exhaust section]

Here is the ring of afterburner injectors located at the exhaust end of the engine:

[Close‑up image of injector ring]

A single injector looks like this:

[Image of injector]

Attached to the engine’s exhaust is a 8‑foot (2.7 m) combustion tube and an adjustable nozzle, with the entire engine measuring roughly 12 feet (4 m) in length.

For more in‑depth technical resources, consult the following links:

[List of relevant external references]