The B-2’s stealth features are still effective—as seen during the weekend strikes, in which the aircraft successfully escaped Iranian airspace unscathed. But the B-21’s technology is far more advanced.
The B-2 Spirit stealth bomber received a renewed burst of attention last weekend after it was used in Operation Midnight Hammer, gaining international recognition for its unique capabilities. Still, the B-2 is an outdated aircraft, slated for retirement once the under-production B-21 Raider enters full production.
From what little is known of the B-21 so far, it outwardly appears to be an updated version of the B-2—a flying wing subsonic strategic bomber with stealth characteristics. But the B-21 is fundamentally its own aircraft, incorporating the generation’s worth of technology that has cropped up since the B-2 was built.
The B-2 first flew in 1989, more than 35 years ago. At that time, the Soviet Union still existed, George H.W. Bush was in office, and Guns ’n Roses were still together. Much has changed since then, both in popular culture and in aircraft design.
While both the B-2 and the B-21 feature the ultra-distinctive flying wing design, the B-21 is smaller and more compact, with a 130-140-foot wingspan relative to the B-2’s 172-foot wingspan. But the primary differences between the aircraft are not the measurements, but the technology. The B-2 features Gen-1 stealth technology, the kind that debuted in the 80s and 90s. This tech is still effective—as seen during the B-2’s weekend strikes, in which the aircraft successfully escaped Iranian airspace unscathed. But the B-21 features far more advanced Gen-5+ technology, the type that is on the cutting edge today.
What does that look like? Well, the B-2 has a radar cross section (RCS) understood to be the size of a bird. The B-21’s RCS is a carefully guarded secret—but understood to be smaller than the B-2s. To achieve a smaller RCS, the B-21 incorporated advancements in stealth design, materials, and system integration. Namely, the aircraft features improved shaping of edges, curves, and exhaust geometry for minimal backscatter and tighter panel alignment with fewer surface disruptions.
Moreover, unlike the B-2, the B-21 was designed using high-fidelity computational electromagnetic (CEM) and AI-assisted optimization. The result is that the placement of every surface, bolt, and seam is calculated to reduce signature across RF, IR, and acoustic spectrums. The result is an aircraft that has 360-degree low observability. For comparison, the B-2 was built with stealth optimization merely from the front, whereas it was much more detectable from the rear.
To enhance its stealth characteristics, the B-21 uses advanced composite materials that are stealthy by nature. Those materials are then coated with a radar-absorbing material (RAM) that is embedded, thinner, and multifunctional. The precise design of this material is, of course, a closely-guarded secret. But it is notable that existing footage of the B-21 makes it appear much brighter than the B-2, whose iron ball paint RAM gives it a distinct midnight-black appearance.
The B-21 also features tighter engine masking, with intakes that are deeply buried with better S-duct shaping. The exhaust is fully shielded, reducing both radar and infrared (IR) visibility. In all likelihood, the B-21 engine incorporates active cooling and low observability nozzles to reduce IR bloom. The B-2, meanwhile, has engines buried in the wing—but the engine inlets and exhaust still produce detectable signatures, which a carefully placed missile might lock on to.
The end result? The B-21 will have all-aspect low observability—thanks to stealth-optimized composites built with AI-assisted technology. Strategically, this translates to an aircraft that could feasibly survive in contested airspace, delivering deep penetration strikes against adversaries more sophisticated than Iran.
About the Author: Harrison Kass
Harrison Kass is a senior defense and national security writer with over 1,000 total pieces on issues involving global affairs. An attorney, pilot, guitarist, and minor pro hockey player, Harrison joined the US Air Force as a Pilot Trainee but was medically discharged. Harrison holds a BA from Lake Forest College, a JD from the University of Oregon, and an MA from New York University. Harrison listens to Dokken.
Image: Wikimedia Commons.
