All of these emerging technical factors continue to inform a growing consensus regarding future war threats -- that the B-21 appears to quite possibly be the only platform that will be able to penetrate certain enemy weapons and advanced air defenses for decades to come.

(Washington, D.C): The Air Force appears to have completed its Critical Design Review of the emerging B-21 bomber, inspiring confidence and optimism that a new-generation of stealth will be ready for war by the mid-2020s, and beyond. The apparent program progress does, at very least, raise the question as to whether to new bomber could be an important element of the service's "faster" acquisition strategy.

Although acquisition and schedule specifics are not discussed regarding the B-21 program, the Air Force's 2018 Acquisition Annual Report does mention "bomber" in the context of its accelerated acquisition strategy. Senior Air Force officials have told Warrior Maven that the Critical Design Review has been underway, and in recent months Air Force Secretary Heather Wilson told reporters the aircraft appears to be on track for the 2020s. While the B-21 is certainly not a program on which the Air Force would cut corners or "speed" up prematurely, the broader service emphasis upon a less-bureaucratic prototpying and development, it seems feasible, could impact the new stealth bomber.

From the Report:

"The traditional acquisition approach buys everything from bombers to blankets. But, a generic approach doesn’t fit all programs perfectly. More importantly, a generic approach can even stall solutions from reaching warfighters. Disciplined internal review of our programs allows us to smartly remove excess steps from the acquisition process. We are fielding tomorrow’s Air Force faster and smarter using prototyping, experimentation and tailored acquisition."

New stealth technology is being pursued with a sense of vigor, in light of rapid global modernization of new Russian and Chinese-built air defense technologies, some of which may make it harder for platforms such as the existing B-2 bomber to operate. Advances in computer processing, digital networking technology and targeting systems now enable some air defenses to detect even stealth aircraft with much greater effectiveness. However, the B-21, is being engineered with this specific challenge in mind -- to ensure a new generation of stealth will be able to penetrate air defenses for decades into the future.

Russian built S-300 and S-400 air defense weapons are able to use digital technology to network “nodes” to one another to pass tracking and targeting data across wide swaths of terrain. New air defenses also use advanced command and control technology to detect aircraft across a much wider spectrum of frequencies than previous systems could. At the same time, while some of these advances may complicate some elements of the mission scope for the legacy B-2, according to senior Air Force developers -- it by no means indicates these current and future air defense will in any way threaten the B-21. For this reason, many military developers, weapons technology experts and observers are echoing a common refrain -- namely that it is imperative for the Air Force to invest heavily in its emerging fleet of B-21 bombers.

For its part, however, the B-2 is not expected to disappear or lose effectiveness anytime soon; the platform is now receiving upgraded materials, a thousand-fold faster computer processor and, perhaps of greatest importance, a new Defensive Management System sensor engineered to locate enemy air defenses - enabling a B-2 to fly around them.

The need for an indispensable “must have” new generation of stealth is emphasized in a recent Mitchell Institute essay – “The Imperative for Stealth.”

The essay’s principle claim, offers a window of substantial detail into comments from Air Force senior leaders that the B-21 will advance stealth technology such that it will be able to hold “any target at risk, anywhere in the world, anytime.”

Broadly speaking, some of the areas of potential improvement are likely focused upon engineering an aircraft with external contours and heat signatures designed to elude detection from enemy radar systems. The absence of defined edges, noticeable heat emissions, weapons hanging on pylons or other easily detectable aircraft features, means that radar "pings" can have trouble receiving a return electromagnetic signal allowing them to identify an approaching bomber. Since the speed of light (electricity) is known, and the time of travel of electromagnetic signals can be determined as well, computer algorithms are then able to determine the precise distance of an enemy object.

However, when it comes to stealth aircraft, the return signal may be either non-existent or of an entirely different character than that of an actual aircraft. A stealth aircraft will, for instance, appear similar in size to that of a bird or insect to enemy radar.

“Even if a radar can detect, it now has to track, and when it transfers that data to engage it will have to shoot a missile using much smaller radar than that used for detection. Also, fusing of the interceptor weapon can be affected by low observability technology,” Ret. Lt. Gen. David Deptula, Dean of the Mitchell Institute for Aerospace Studies, told Warrior Maven in an interview earlier this year.

Barriers related to hitting stealth aircraft also include electronic warfare “jamming” defenses, operating during adverse weather conditions to lower the acoustic signature and conducting attacks in tandem with other less-stealthy aircraft likely to command attention from enemy air defense systems.

EW is likely to figure prominently, in part because emerging hardware configurations are now engineered to quickly embrace software upgrades as new threats emerge, such as yet-to-be-seen frequency combinations or radar-detection ranges. With this in mind, EW for the B-21, aligns with the thinking outlined in the Mitchell Institute essay, which explains that newer stealth technology is engineered to outmatch multi-frequency air defenses.

The B-21 image released by the USAF depicts a design that does not use vertical flight control surfaces like tails. Without vertical surfaces to reflect radar from side aspects, the new bomber will have an RCS (Radar Cross Section) that reduces returns not only from the front and rear but also from the sides, making detection from any angle a challenge, the Mitchell Institute writes.

On the topic of RCS, an interesting essay called “Radar and Laser Cross-Section Engineering,” from the Aerospace Research Central, cites the emergence of new coating technologies, including “radar-absorbing materials and artificial metamaterials.” (Text written by David Jenn, an author from the Naval Postgraduate School).

Newer methods of IR or thermal signature reduction are connected to engine and exhaust placement. Internally configured engines, coupled with exhaust pipes on the top of an aircraft can massively lower the heat emissions from an aircraft, such as the structure of the current B-2 - the authors of the essay say.

All of these emerging technical factors continue to inform a growing consensus regarding future war threats -- that the B-21 appears to quite possibly be the only platform that will be able to penetrate certain enemy weapons and advanced air defenses for decades to come. While stand-off weapons are anticipated to bring substantial tactical advantage, destroying enemy air defenses and pinpointing targets in closer proximity, to open up an air corridor for other attacking air assets, appears to many as an absolute necessity. For instance, mobile air defenses can quickly change position, new targets can emerge and certain weapons such as EW application might need to operate within a closer range than stand-off platforms to be effective.

Part of this consensus, according to Senior Air Force weapons developers, is implicitly built upon the fact that the B-21 is being engineered to be perpetually upgradeable. Among other things, this means that new software, sensors, weapons, computers and avionics can quickly emerge as they become available.

Kris Osborn is a Senior Fellow at The Lexington Institute. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army - Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He also has a Masters Degree in Comparative Literature from Columbia University.