During the Second World War, the advent of radar gave Allied Forces the ability to detect approaching enemy aircraft and prepare their defenses in advance. Though a secret at the time, radar has been used in everything, from aircraft and weather forecasting, to astronomy and even medicine. But if radar can detect an aircraft in the sky, how does stealth work and what makes the B-2 Spirit “Stealth Bomber” so special?
The Invention of Radar
In the late 19th century, Heinrich Hertz showed that metallic objects reflect radio waves, which were later used by a German inventor to detect ships in heavy fog and avoid collisions. By the early 20th century, technology advanced, and larger, more powerful transmitters were developed, capable of detecting smaller objects, like aircraft. At the outset of World War II, the British had already completed construction of a series of radar towers, known as the Chain Home early warning system.
Later named RADAR (RAdio Detection And Ranging), this early warning system transmitted multiple, small electromagnetic pulses in a straight line from a central location. If these waves encountered an object, they were scattered in multiple directions with a small portion returning to the transmission point.
Stealth works by absorbing some of these waves and scattering the rest away from the receiver. However, stealth technology and the aircraft capable of exploiting this principle weren’t developed until the 1970s.
Even then, it was 1988 before the world’s first, true Stealth aircraft, the F-117 Nighthawk, was introduced to the public. Designed and produced by the Skunk Works division of Lockheed, the Nighthawk’s unique, angular design gave it the capability of traversing through radar with minimal detection. Unfortunately, due to its groundbreaking design, the aircraft also had several limitations—it could carry only two bombs in internal bays and was approved for night operations only.
Lockheed was not the only developer tasked with developing a stealth aircraft. The Defense Department had also determined there was need for a long-range, strategic bomber capable of penetrating enemy radar undetected and destroying key targets. Fortunately, Northrop had been testing a “flying wing” concept since the end of the Second World War, which included a number of natural stealth characteristics.
Rather than angular, hard edges, the B-2 employed a blended wing which increased aerodynamics and range. This meant the B-2 had no central fuselage or vertical surface, instead using computer-controlled flight surfaces to maintain stability. Combined with its radar-absorbent coating and low-observation technologies, the B-2 Spirit could evade detection by enemy radar.
Since its introduction in 1997, the B-2 has never been fired upon by enemy missile, something the F-117 fell prey to in 1999, resulting in the only successful downing of a stealth aircraft by enemy fire.
Since the introduction of the F-117 Nighthawk and B-2 Spirit, the stealth world has seen multiple innovations. The F-22 Raptor and F-35 Lightning II have entered service as fifth generation U.S. stealth fighters. F-35 fighter wings include the 388th and 419th stationed at Hill Air Force Base (AFB), encompassing some 78 active fighters. Hill AFB is also home to the Ogden Air Logistics Complex, which handles the repair and refurbishment of all aircraft landing gear, across the entire U.S. Air Force, including the F-117 and B-2.
Alongside these incredible capable aircraft, multiple stealth-capable air, ground and sea vehicles have been developed, both manned and unmanned. As of 2008, some three decades after entering service, the F-117 was retired, though several remain in use for various testing and training missions.
Meanwhile, by the late 2020s, Northrop developed and introduced the B-21 Raider long-range, stealth bomber. Incorporating the latest in low-observable technologies, radar-absorbent materials and over three decades of innovation, the Raider is sure to become the world’s most advanced bomber. The U.S. Air Force currently plans on retiring the B-2 no later than 2032.
Hill Aerospace Museum
To learn more on the history of stealth and to see an F-117 Nighthawk up-close, visit the Hill Aerospace Museum today, where admission is always free!