The Science Behind Fighter Jet Afterburners Explained

Watching a fighter jet take off is a beautiful sight. Anyone who hasn't been to an air show should really try to see one of the incredible air shows that captivate aviation enthusiasts worldwide at least once. Once you get past the roaring crescendo of its engines revving up, seeing a fighter jet race down the runway before lifting off the ground and soaring through the sky with a trail of fire erupting from its tail is a truly enlightening sight. It shows you just how far technology has advanced since the Wright Brothers.

Take away the incredible features in modern fighter jets like the hidden weaponry and science behind stealth capabilities and you're still left with a vehicle capable of amazing feats unimaginable more than half a century ago. The afterburner that gets the jet off the ground and up to sound breaking speeds alone is a technological marvel. Most people take it for granted, not realizing the science that goes into moving a jet at supersonic speeds.

A plane can get off the ground without an afterburner — passenger planes do it all the time. Modern-day fighter jets, on the other hand, make frequent use of afterburners to achieve liftoff, especially when they're taking off from aircraft carriers. Fighter jets are considerably heavier than prop planes from World War II between the materials used to manufacture them and their armament. They need to stay small and fast, so even the engines on a Boeing 747 wouldn't work. The afterburner gives jets that little extra boost to takeoff.

Afterburners are used on modern day fighter jets to help give them enough thrust to takeoff , specifically on an aircraft carrier, as well as to fly faster than the speed of sound when they need to get somewhere quick. When the pilot engages the afterburner, it creates a reaction that erupts enough force to propel the jet forward. The fuel (usually kerosene) enters the engine through hundreds of tiny holes and is combined with the air already being sucked in. A device that creates an electric spark ignites the fuel, forcing it to expand the oxygen in the air stream. The heat generated from the air and fuel shoots out of the exhaust, creating the pilot's desired thrust.

The engine is designed in such a way that the flames from the exploding fuel don't touch its walls, otherwise it could burn through and damage it. 3,000 degrees Fahrenheit has no problem tearing through most materials. Luckily, the air is colder at higher altitudes, which adds a layer of protection.

When the afterburner isn't engaged and the jet is flying at cruising speed, the engine acts as a typical turbojet. It might add an extra 50% of thrust, but pilots have to use the afterburner sparingly or risk running out of fuel too fast.

Typically, it's only fighter jets that utilize afterburners since few other aircraft fly at supersonic speeds. However, there have been a couple of non-fighter jets that made use of afterburners, one in particular that remains iconic to this day: the Concorde. Though it wasn't a fighter jet, the Concorde was a one-of-a-kind supersonic passenger plane that flew Mach 2.04, or 1,354 mph, bringing travelers from New York to London in just under three hours time. By comparison, it takes the average passenger airline around seven hours to make the same flight today. 

The iconic Concorde made use of afterburners during take-off and a part of the flight when a boost was needed to get the passenger plane to its full blistering-fast operational speed. Unfortunately, after a Concorde flight crashed in 2000, the airline retired the plane in 2003, putting an end to supersonic flights for civilians.

Afterburners are an essential piece of fighter jets and will continue to be used well into the 21st century. However, they're not without their drawbacks. Stealth has become a vital component for fighter jets. Getting in and out of enemy territory without being detected is an invaluable feature that can't be understated. Unfortunately, when pilots engage the afterburner, they're exposed to radar waves and infrared detection devices. Newer jets like the F-22 Raptor can cruise faster than the speed of sound without engaging the afterburner, which is helpful but not perfect. As of now, there's no way to hide the immense heat erupting from the rear of a plane.

Besides stealth, jets always have a need to go faster, farther, and use less fuel. Small start-ups like Destinus are developing hydrogen-powered afterburners that can aid in those endeavors. Its afterburner is only capable of reaching roughly 150 mph, a far cry from its supersonic and eventual hypersonic goal. If Destinus manages to create a hydrogen-powered afterburner at the very least keep pace with their kerosene-power counterparts, it's only a matter of time before militaries around the world integrate that technology into their fighter jets.