B-2 Spirit – A Closer Look at the Stealth Technology in the World’s Most Expensive Aircraft

B-2 Spirit's Radar-Defying Design, Overcoming Skepticism to Become a Military Game Changer.

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Girish Linganna
Girish Linganna
Girish Linganna is a Defence & Aerospace analyst and is the Director of ADD Engineering Components (India) Pvt Ltd, a subsidiary of ADD Engineering GmbH, Germany with manufacturing units in Russia. He is Consulting Editor Industry and Defense at Frontier India.

The United States Air Force Global Strike Command posted a video of a Whiteman Air Force Base B-2 Spirit soaring over the first NFL game of the season on September 7, demonstrating the readiness of its bomber fleets. Beginning in September, the B-2 Spirit landed at the Ørland base in Norway to “refuel” without shutting down its engines before continuing its mission. This procedure, which resembles a Formula 1 pit stop, makes it possible to speed up flight operations. It eliminates the need to repeat the lengthy and intricate process of starting the reactors on a B-2 aircraft. The B-2’s long-range penetration and strike capabilities are genuinely unparalleled, and stealth is one of the key enabling factors.

Steve Sullivan, vice president of Northrop Grumman Corporation’s Strike Division, in an interview with Breaking Defence published on August 3, 2021, revealed a set of stealth characteristics of B2 while explaining the latest stealth coat of B-21 Bomber. He said the company had devised a stealthy coating with revolutionary repairability for the new B-21 Raider bomber.

B-2 Spirit Flies over NFL Game.

Sullivan characterised the B2 Spirit, the present stealth bomber developed in the late 1980s, as revolutionary. According to Sullivan, when designing the most recent bomber, all the flaws and difficulties encountered during the development and operation of its predecessor were taken into account.

He noted that operating the B-2 required substantial expenditures and highly skilled, specialised personnel. Due to the sensitivity of the stealth coating, the aircraft had to be stored in specialised hangars that adhered to strict temperature and humidity parameters.

Along with stealth, the Northrop representative emphasised that maintainability was one of the B-21’s primary requirements from the very beginning. According to Sullivan, the new bomber’s radio-absorbing coating is just as revolutionary in terms of durability and repairability as the B-2’s coating was in terms of stealth capability.

Specialised coatings are highly resistant to minor defects, eradicating the need for frequent replacements to preserve the bomber’s stealth characteristics, as Sullivan explained. In addition, the new coatings will be significantly more resistant to a broad spectrum of temperatures and varying humidity levels in hangars.

Finally, Northrop Grumman has reduced the time required for technical maintenance, allowing the new bomber to engage in combat missions without lengthy maintenance breaks.

B2 Stealth Bomber

The B-2A’s flying wing shape, devoid of vertical tail surfaces, utilises cutting-edge LO (Low Observability) technology, earning it the nickname “Stealth Bomber.” Its cellular structure and radio-absorbing coating, primarily composed of carbon fibre-graphite and epoxy resin, make it highly stealthy and difficult to detect by radar.

The B-2 Spirit is also the most expensive aircraft of the 20th century, with an estimated unit cost of $3 billion in 2020 (including research, development, and testing). This is one reason why its design sparked debate in the United States Congress and among the Joint Chiefs of Staff. The fact that only 21 of the originally intended 132 units were constructed partially explains the high cost per unit.

The B-2 Spirit is propelled by four General Electric F118 turbofan engines with a thrust of 77 kN each and is equipped with two bomb bays capable of carrying a theoretical maximum payload of approximately 35 tonnes of various bombs and missiles.

The United States Air Force requested a strategic bomber to complement or even replace the Rockwell B-1B in 1981.

U.S. Air Force’s B-2 Spirit stealth bombers are in Iceland as part of a Bomber Task Force mission.
U.S. Air Force’s B-2 Spirit stealth bombers are in Iceland as part of a Bomber Task Force mission. Image: U.S. Mission to NATO

The first flight of the B-2 Spirit, also known as the “Spirit of America,” occurred on July 17, 1989, and the USAF accepted the first operational aircraft in late 1993. Initially conceived for strategic bombardment missions against Soviet targets armed with conventional or nuclear weapons during the Cold War, the B-2 Spirit saw its first combat deployment in 1999 during the Kosovo War against Serbia. It later participated in the conflicts in Afghanistan in 2001, Iraq in 2003, Libya in 2011, and 2017.

Long ago, many of the B-2’s characteristics remained classified. The United States Department of Defence has never disclosed the precise mass and velocity parameters, instead using the ambiguous term “high subsonic” to describe them. Everything on the covert strategic bomber is designed to have low infrared, acoustic, electromagnetic, visual, and radar signatures. Similarly, the endeavour was kept secret from both the general public and the military. Most USAF leadership believed that the Rockwell B-1B bomber was a top priority, while few were aware of the B-2 programme.

About 80% of the B-2 Spirit’s mass is comprised of radar-absorbing composite materials, specifically a graphite/epoxy resin honeycomb structure manufactured by the US subsidiary of Saint-Gobain.

As mentioned earlier, the B-2 is a flying wing design, which means it lacks a fuselage and a tail; its highly aerodynamic shape and invisibility provide it with a significant advantage over previous bombers, as does its high bomb-carrying capacity. A minimal radar signature affords the aircraft greater freedom of action at high altitudes, thereby expanding the range and field of view of onboard systems. 

The B-2 Spirit’s forward-swept leading edge – 33° and sawtooth trailing edge are designed to deflect radar radiation. Planform alignment is the technique used to apply various angles to the leading and trailing edges. This allows the adversary radar to detect only two possible aircraft orientations in which radar reflectivity is maximised, thereby reducing the likelihood of detection significantly. This design characteristic is also evident on the Lockheed Martin F-22 Raptor, whose surfaces are all inclined at the same angle and offsets.

Other passive detection measures include curved S-shaped air intakes (S-ducts) and invisible dielectric panels covering the radar with synthetic aperture, preventing the antenna from rotating while reflecting radar waves while maintaining regular operation.

The four General Electric F118-GE-100 non-afterburning turbofan engines reduce their infrared signature, and the reactor exhaust gases are routed through top-mounted, offset V-shaped nozzles to conceal the heat sources from ground detectors. Allegedly, chlorofluorosulfonic acid was injected into the exhaust stream to prevent the formation of contrails. But the final design came with a contrail sensor that alerts the pilot when he should change altitude. Mission planning also takes into account altitudes at which the likelihood of their formation is minimal.

Stealth Demonstration

When the American B-2 stealth bomber was first introduced, some Russian military experts expressed scepticism, claiming that the aircraft’s stealth capabilities were merely a marketing stratagem by the manufacturer to reach into the pockets of American taxpayers. They argued that Soviet-made radars with wavelengths in the metre range could readily detect American aircraft. However, it was not made clear that potential adversaries of the United States did not possess such radar systems, and even if they did, operating and maintaining them would be exceedingly difficult for various reasons.

This scepticism and dismissal of the B-2’s capabilities is somewhat typical in the military, where new technology is frequently greeted with initial scepticism until its effectiveness has been in practice. Its effective operational history has demonstrated the B-2’s impressive stealth capabilities, and has become a vital component of the United States’ strategic bomber fleet. The Chinese strategic bomber of the next iteration, the H-20, closely resembles the B2 Spirit.

(Inputs taken from Vrunda Sekhar)


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