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by Kris Osborn

An upcoming Critical Design Review of the Air Force’s new B-21 Raider stealth bomber will examine design specs, assess technical maturity and seek to prepare the aircraft to fly against fast-evolving, future air defenses.

Air Force senior leaders say the engineering and technological “intent” when building the B-21 is to construct a platform that able to counter current cutting-edge threats as well as threats anticipated to surface in coming decades.

Essentially, Air Force and Northrop Grumman engineers are architecting the aircraft with a mind to being able to elude enemy air defenses well into the 2030s, 2040s and beyond.

“We build with an open mission system architecture so that as the threat evolves, we can rapidly adapt the airplane to jump – and address things that are constantly changing,” Lt. Gen. Arnold Bunch, Military Deputy, Office of the Assistant Secretary of the Air Force for Acquisition, told Scout Warrior in an interview.

While many details of the upcoming technical review are not expected to be available for security reasons, Air Force senior developers do emphasize that the new stealth bomber is being designed to quickly evolve as needed.

Open mission systems, as described by Bunch, involves building a set of common standards and interfaces with software, hardware, sensors, radar, countermeasures and even weapons technology; this include IP protocol and common hardware able to receive software upgrades as required. The concept is to expedite integration of upgrades or changes to the platform as required by the current threat environment. Faster incorporation of needed adjustments is therefore regarded as a crucial means of sustaining a technological advantage.

While describing the rationale for this effort, Bunch emphasized that the US technological advantage and domination of the skies is by no means as expansive as it was in recent decades, a circumstance which further underscores the need to innovate and rapidly adapt.

“We are the most dominant air power the world has ever seen. We’ve done that with a lot of our technologies which have been used for years in a constant state of combat. The world has adapted and they have watched. They have updated their defenses,” Bunch said.

Critical Design Review is a more rigorous and throughout assessment which follows the now-completed preliminary design review. Ensuring that the pursuit, integration and execution of the technologies in the aircraft are consistent with the plans and requirements for the bomber established by Air Force and industry developers.

Unresolved and strongly contested questions about whether next-generation stealth technology will be able to elude current and future surface-to-air-missile systems seem to have found a permanent resting place in the collective consciousness of analysts, weapons developers and military leaders around the world. Some maintain that new advances in radar evading technology will sustain stealth dominance, whereas others have gone so far as to raise the question whether stealth technology itself may become obsolete.

Regardless of where a given perspective might fall within a broad continuum of varying viewpoints, there are a few unambiguous and irrefutable elements to the equation – such as the often-discussed cyclical process of international military technological competition. Technical advances, to the extent they are known by an adversary, often generate a specific reaction or “counter” approach designed to thwart or minimize any advantage.

Naturally, such countermeasures then in turn inspire new advances. Military rivals seek to place potential adversaries behind their latest innovations while also forcing an enemy to operate behind the cost curve – essentially require and enemy to spend far too much money trying to keep pace with newly established military technological superiority.

Air Force B-21 technology developers are, of course, aware of this phenomenon.

There is perhaps no more visible or relevant example of this than emerging air defense technologies and their respective ability to detect and attack even stealth aircraft. Russian-built S-300s and S-400s and Chinese HQ-9 air defenses are key examples of systems now being rapidly upgraded as technology advances.

Increasingly sophisticated air defenses, such as these, now use faster processors, digital networking and sensors to track even stealthy aircraft on a wider range of frequencies at longer ranges. These frequencies include UHF, VHF and X-band, among others.

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Certain low-frequency “surveillance” radar technologies are able to determine if an enemy aircraft is in the vicinity, whereas other high-frequency bands, called “engagement” radar, can track, target and destroy aircraft. If a stealth aircraft is able to avoid being targeted, but is still detected by lower frequency “surveillance” radar – it may need to rely upon air-to-air superiority or dogfighting skill to counter enemy aircraft sent up to attack.

Bombers, such as the B-2 and B-21, therefore have a distinct and challenging mission; they are not built to dogfight but rather use heat suppression and stealth configuration to avoid or elude enemy air defenses altogether. The idea is to identify and destroy targets, without an enemy ever knowing it is there. The B-2 bomber, for example, is being upgraded with a technology called the Defensive Management System.

Read Scout Warriors Detailed B-2 Upgrade Story HERE

This technology, now being integrated into the B-2, will better enable the stealth bomber to know the location of enemy air defenses to avoid being detected or entering their target envelope. This is an example of technological innovations being used to better enable the B-2 to operate successfully in a modern, more high-threat environment.

While many observers have pointed out that the Air Force’s released “image” of the B-21 resembles a B-2 in many respects, service leaders have been both clear and very “general” about the fact that the B-21 consists of many not-yet-seen technologies. Some observers have said that the Air Force image of the B-21 shows a fuselage without visible exhaust pipes like those seen on a B-2. This could mean absolutely nothing -- or it could be early evidence of next-generation heat-suppression technology designed to remove a stealth aircraft’s detectability by eliminating its radar and heat signature.

Stealth technology works by 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, radar "pings" 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-existence or of an entirely different character than that of an actual aircraft.

Russian & Chinese Air Defenses

Russian S-400s can carry four different types of missiles designed to hit short, medium and long-range air targets; Multiple reports place the weapon’s range as spanning from 40 to 400km. This kind of range can make operations difficult for even high-altitude bombers such as the B-2 and B-21. The weapons are made by a Russian firm called Rostec State Corporation.

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Emerging computer processing power allows radar to interface with fire control much more rapidly – all while drawing upon newer networking technologies to link across a system of defensive weapons. Fast-moving targets, as a result, can be identified and passed from one “field of view” or target envelope to another. This can preclude an aircraft’s ability, in some instances, to rely upon speed and rapid maneuverability to avoid detection. Furthermore, road-mobile air defenses can make networking easier and more expansive, a technique which only further challenges aerial maneuverability for stealth aircraft.

S-400s are intended to destroy aircraft, drones, cruise missiles, helicopters and even some ground targets. The National Interest has reported that Russia is now working on an S-500 system able to destroy even stealthy targets at distances up to 125 miles.

Russian media reports have claimed that stealth technology is useless against their air defenses. While Russian built S-300 and S-400 air defenses are believed by many experts to be among the best in the world, it is safe to say that these Russian claims may not espouse a view shared by the US Air Force or experts working on next-generation stealth.

Chinese-built HQ-9 air defenses are also a cause for concern among US observers. News reports from and Defence International say the missile fires a 180kg warhead, travels at a speed of Mach 4.2 and operates at a maximum range of 200km. These weapons, first developed in the 1980s, have also been upgraded over the years, according to many news reports. The HQ-9s are built by the China Precision Machinery Import-Export Corporation.

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The Chinese military also appears to be acquiring Russian-built S-400s. A report earlier this year from Sputnik International cited Russian Rostec weapons developers stating that Chinese- purchased S-400s will arrive in China by 2018.

As the debates, discussions and comparisons surge forward – it seems clear that tomorrow’s stealth technology is likely to be very different than that which operates today.

“B-21 will provide us a continued ability to hold targets anywhere around the world at risk,” Bunch said.