Radar-absorbent materials (RAM) play a key role in determining the effectiveness of an aircraft’s stealth performance.
As stealth performance becomes a design cornerstone of military aircraft, it is essential to examine the various technologies by which an aircraft achieves stealth. The most important of these is “radar-absorbent materials” (RAM), which play a critical role in modern stealth technology, greatly influencing the design and operational effectiveness of military aircraft.
What Are Radar-Absorbent Materials?
RAM refers to materials that are explicitly designed to absorb radar waves rather than reflect them, reducing the aircraft’s radar cross section (RCS) and making it less visible to radar systems. Stealth performance has become vital in modern warfare, where air defense systems have grown remarkably sophisticated, capable of identifying, tracking, and destroying airborne threats from great distances.
How Do Radar-Absorbent Materials Work?
To reduce an aircraft’s RCS, RAM acts to convert incident radar energy into heat or redirect incident radar energy away from the surface of the aircraft. RAM allows an aircraft to avoid detection by reducing the amount of radar energy that is reflected to enemy radar, which increases the aircraft’s survivability during operations that occur behind enemy lines, such as reconnaissance, deep penetration strikes, or suppression of enemy air defenses (SEAD).
How Are Radar-Absorbent Materials Made?
Various materials are used to make RAM, including carbon-based substances, ferrite-based coatings, and conductive polymers. The material is typically embedded in paints or applied as coatings over the surface of the aircraft. The RAM can occasionally be manufactured directly into the structure of the aircraft itself, through composite materials that are used to construct the airframe.
Which Planes Use Radar-Absorbent Materials?
Perhaps the most famous application of RAM was on the Lockheed F-117 Nighthawk, the world’s first operational stealth aircraft. The F-117 lowered its RCS through a combination of faceted surfaces and RAM coatings. The result was an aircraft with such a dramatically reduced RCS that it was virtually invisible to radars of its day, ushering in the stealth era of military aviation. In the years since, radar has become more effective—infamously resulting in the shootdown of an F-117 over Serbia in 1999—but other aircraft have become stealthier as well, in part by incorporating even more sophisticated RAM materials into the finished product.
The greatest stealth planes of the modern era include the Lockheed Martin F-22 Raptor and Lockheed Martin F-35 Lightning II.
How Effective Are Radar-Absorbent Materials?
The effectiveness of RAM depends on multiple factors, including thickness, frequency, range of absorption, angle of incidence, and environmental durability. RAM designers must engineer the material to absorb radar waves across a broad spectrum of frequencies.
Complicating matters, environmental conditions such as rain, UV exposure, and temperature can significantly impact RAM performance, which is why RAM designers are constantly working to upgrade the robustness and longevity of the material.
What Does It Take to Keep Stealth Aircraft Stealthy?
Stealth aircraft also often require extensive maintenance regimes to preserve the integrity of RAM coatings, as any degradation can compromise stealth performance and cause the aircraft to be less survivable. This in turn leads to skyrocketing maintenance costs.
As enemy air defense systems continue to evolve, and the corresponding demands on stealth performance increase, expect RAM development to keep pace, as the material is a critical factor in determining the effectiveness of an aircraft’s stealth performance.
About the Author: Harrison Kass
Harrison Kass is a Senior Defense and National Security Writer at The National Interest. Kass is an attorney and former political candidate who joined the US Air Force as a pilot trainee before being medically discharged. He focuses on military strategy, aerospace, and global security affairs. He holds a JD from the University of Oregon and a master’s in Global Journalism and International Relations from NYU.
Image: Wikimedia Commons.
