Reports of Stealth’s Death are Greatly Exaggerated

The role of stealth aircraft has been a touchy subject ever since the F-117 Nighthawk was unveiled to the public in 1988. Stealth technology allows missions that might not have been possible before, but it also requires a huge investment and reliance on sometimes finicky technology. In his report with the Center for Strategic and Budgetary Assessments think tank, Barry Watts points out that stealth aircraft make up a relatively small fraction of the U.S. fighter and bomber fleets — some 5.5%. With so small an investment, it begs the question of whether stealth aircraft can outpace the advances being made in detection technology.

The threats against stealth aircraft are far more sophisticated than they were 13 years ago. Watts discusses the use of longer-wavelength radar systems that take advantage of UHF and VHF radars. Because these are longer wavelength systems, the radar cross section of even stealthy airplanes will appear much larger. There are many technical and logistical hurtles to overcome, but Watts postulates that fully digital active electronically scanned arrays (AESAs) could soon be a real threat.

One of the most intriguing anti-stealth technologies is the VERA-E, which from Watts’ description sounds like a crowd sourcing approach to radar defense. From the article:

The other promising approach to counter LO has been passive systems such as the Czech VERA-E, which uses radar, television, cellular phone and other available signals of opportunity reflected off stealthy aircraft to find and track them. The main limitation of such systems has been the enormous signal-processing power and memory required to analyze all these emissions, differentiate real targets from ghost signals, noise and clutter, and keep the false alarm rate to manageable levels.

One potential outcome, however, is that as long-wave radars transition to AESAs (and assuming computational power continues to double every two years or so in accordance with Gordon Moore’s “law”), information acquisition will overwhelm the capacity of aerospace engineers to reduce platform signatures. The balance between information acquisition and information denial will swing dramatically in favor of the former. Or, to put the point more bluntly, there will come a time in the not-too-distant future when the SAMs will almost always win against air-breathing penetrating platforms, rendering operations inside denied airspace too costly to bear.

Unlike the other technologies discussed in the article, VERA-E sounds as if it would use less physical infrastructure and more analytical power than other systems. Were it to be refined, this technology could give developing nations a leg up in developing their anti-stealth defenses without having to invest in a large network.

Of course, the development of stealth technology has not been entirely stagnant. Watts points out that the F-35 is capable of changing its course and responding to threats as they occur without greatly diminishing its stealthiness — a problem for older stealth aircraft. It also carries digital radio frequency memory (DRFM) countermeasures, that beam inaccurate information to enemy radar systems. Again, from the paper:

A DRFM countermeasures system can duplicate an incoming signal from enemy radars by converting it from analog to digital and back again. In between, DRFM can modify the digital duplicate so that, when converted back to analog and retransmitted, the manipulated signal will be coherent with the threat radar. DRFM signal manipulation can deceive threat radars by altering the target’s apparent RCS, range, velocity, and angle.

Furthermore, the F-22 and F-35 fighters are expected to operate in networked groups, increasing their collective abilities.

The greatest evidence Watts offers stealth technology is not doomed to be overwhelmed by sensing technology is the Department of Defense’s own procurement strategy. If the DoD continues with their plans to acquire 2,443 stealthy F-35s by 2035, all-aspect low-observable aircraft will represent some 70% of the fleet. That alone is a powerful endorsement.

It is, of course, a leading question to ask if “stealth is dead.” Once the genie is out of the bottle, it cannot be put back in; even if stealth as we understood it was greatly diminished it would still be an aspect of defense planning. Rather than making a case one way or another, Watts presents a valuable overview of the technological battlefield between those who wish to remain unseen and the forces searching for them.

(CSBA via DoD Buzz, image via Lockheed Martin)

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