Commercial aircraft like the Boeing 747 and Airbus A380 have four engines, whereas a Lockheed F-16 fighter jet only has one engine. But how come the sound of one F-16 engine is as loud as that of two 747s or even more? Even newer jet fighters like the F-35 Lightning II are still very loud. Well, that’s because of the type of engine they use, which is intended for their specific purpose. Fighter jets uses turbojet engines, which give them their loud sound.
Fighter jets, known for their dramatic and thunderous sound, are louder than commercial aircraft, often reaching a staggering 140 decibels. This intensity of sound, is only 40 decibels shy of causing permanent hearing damage.
The answer lies in the nature of jet engines and the specific design of those used in fighter jets. Jet engines operate by drawing in large amounts of air, combusting it with fuel, and igniting it into a hot gas that propels the aircraft. Fighter jets are equipped with low-bypass jet engines capable of flying at supersonic speeds, exceeding the speed of sound (1,225 km/h or 761 mph). These engines are often fitted with afterburners, which provide a significant boost in speed and thrust, contributing to the fighter jets’ ear-splitting sound.
Jet Engine Design and Its Impact on Sound
To understand the loudness of fighter jets, it’s essential to examine the jet engine’s structure. A typical jet engine comprises several parts, including the fan, compressor, combustion chamber, and exhaust. The fan, visible from the front of the engine, draws in air and funnels it to the compressor, which increases the air’s pressure up to 12 times. The compressed air then mixes with fuel in the combustion chamber, igniting and expanding rapidly. This expanding gas escapes through the engine’s rear, propelling the aircraft forward.
The jet engine, a marvel of aviation engineering, has evolved since its invention by Sir Frank Whittle in 1937. Despite advancements, the fundamental principles of Whittle’s pioneering design remain unchanged. These engines emit high temperatures and loud sounds, playing a role in the success of military aviation, particularly during World War II.
Comparing Fighter Jets and Commercial Aircraft
The difference in noise levels between fighter jets and commercial aircraft can be attributed to their respective engine designs and operational requirements. Commercial jets, while still loud, do not produce the same roaring noise as fighter jets. This disparity is due to the absence of afterburners and the different operational speeds and altitudes of commercial aircraft.
Aircraft noise measurements reveal the stark contrast in loudness. A jet taking off produces 150 dB of noise at 80 feet, potentially causing eardrum rupture. In comparison, a Boeing 737 during landing at 6,080 feet produces 97 dB. Military jets with afterburners taking off from an aircraft carrier reach 130 dB at 50 feet, illustrating the significant impact of afterburners on noise levels.
The loudness of fighter jets is an inherent characteristic resulting from their specialized jet engines and the use of afterburners. These engines, designed for supersonic speeds and enhanced thrust, inevitably produce a thunderous sound that distinguishes fighter jets from commercial aircraft.
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