| f22 |
Pro Stealth
Stealth isn’t becoming obsolete anytime soon: USAF - 11/30/2012 - Flight GlobalStealth technology is not going to be rendered obsolete anytime soon, a top US Air Force official says.
"Our adversaries are building capabilities to see stealth airplanes," says Gen Mike Hostage, commander of Air Combat Command, speaking at the Center for Strategic and International Studies on 30 November. "But not at any faster rate than we're developing abilities to remain, not invisible, but able to deal with the relative visibility and invisibility."
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There will have to be a sixth-generation fighter at some point, which Hostage says is notionally around 2030. Unlike fifth-generation fighters, where Hostage says the definitive technology is stealth, there may not be one particular attribute that defines a sixth-generation machine. There could a combination of several emerging technologies, but it is too early to say. "It'll be some type of game-changing capability," Hostage says. "It's not going to be an iterative growth of this capability."
U.S. Commission on National Security/21st Century NWR_A.pdf
There
will be a greater premium on highly integrated and rapidly deployable
forces. The age-old interaction of capabilities and counter-measures
will continue, of course, and physics probably favors detection and
the ultimate demise of stealthy systems and large platforms. But “ultimate” can mean a long time, and, as opponents try to defeat existing U.S. technologies, new technologies and ways of employing these weapons will abet the continuation of current U.S. advantages.
Stealth Con
A Cold War Legacy: The Decline of Stealth“Physics probably favors detection and the ultimate demise of stealthy systems.” So predicted the Hart-Rudman Commission in 1999. [see above for full context of quote.] Sixteen years later, it’s time for the Department of Defense to ask tough questions about whether to continue investing scarce resources into stealth technology. Foremost among those questions is this: Are we sacrificing too much capacity in a quest for an exquisite capability, a capability that may not offer the edge it once did and whose efficacy is in decline?
Russian / PLA Low Band Surveillance Radar Systems (Counter Low Observable Technology Radars)
Prior to the rout of Saddam's extensive IADS [30 years ago] in the 1991 Desert Storm campaign, the Soviets did not take US stealth technology seriously. Desert Storm changed that entirely, and the Soviets launched an effort to develop capabilities to detect VLO aircraft. With the collapse of the USSR funding dried up, but Russian design bureaus including NNIIRT, well known for their line of P-18 Spoon Rest VHF band radars, continued developing new systems operating in the lower bands - from VHF through UHF to L-band.
Most stealth design features are intended to scatter incoming illumination in a controlled fashion, evidenced by the use of edge alignment, faceting and other geometrical shaping features, supplemented by the use of absorbent materials. All of these techniques are intended to defeat radars operating in the geometrical optics and less frequently, resonance regimes of scattering. The precondition for this to work is that the wavelength be much shorter than the cardinal dimensions of the shaping feature of interest. An edge aligned engine inlet of typical dimensions will perform best in the centimetric Ku- and X-bands, and less so with increasing radar wavelength.
The Russian approach has been to invest in the further development of low band radars, especially operating in the VHF band. With wavelengths of the order of a metre or more, only very large stealth aircraft (e.g. B-2A) satisfy the physics requirement for geometrical optics regime scattering. A fighter sized aircraft such as the JSF will see most of its carefully designed shaping features fall into the resonance or Raleigh scattering regions, where shaping is of little or no import, and skin depth penetration of the induced electrical surface currents defeats most absorbent coatings or laminates.
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| Counter Stealth has to be considered |
The Northrop Grumman E-2D Advanced Hawkeye maybe the U.S. Navy’s secret weapon against the emerging threat of enemy fifth-generation stealth fighters and cruise missiles.
The key to that capability is the aircraft’s powerful UHF-band hybrid mechanical/electronically-scanned AN/APY-9 radar built by Lockheed Martin. Both friend and foe alike have touted UHF radars as an effective countermeasure to stealth technology.
One example of that is a paper prepared by Arend Westra that appeared in the National Defense University’s Joint Forces Quarterly academic journal in the 4th quarter issue of 2009 .
“It is the physics of longer wavelength and resonance that enables VHF and UHF radar to detect stealth aircraft,” Westra wrote in his article titled[ p.139- 143] Radar vs. Stealth.
Commentary: Do Russian Radar Developments Challenge Stealth? | Defense content from Aviation Week
“The price of increasing wavelength . . . is that the antenna has to grow in proportion to the wavelength in order to maintain a narrow beam and adequate resolution. The ‘mobile’ Soviet VHF radars are cumbersome, and early-warning radars such as Tall King (P-14) are large fixed structures and provide coverage of only one sector. Despite the size of their antennae, they are not accurate enough to manage a complete engagement.”
The Pentagon’s then-stealth technology director, Paul Kaminski, commissioned an aggressive Red Team in the very early 1980s that had both recognized the threat from VHF radars and discerned that it could be mitigated by artful mission planning [good against a fixed defense]. The Red Team’s work led to the development of the computer-driven route planner that F-117 pilots, fond of a vampish TV horror-movie hostess, nicknamed Elvira.
The same assessments applied when the requirements for the F-35 Joint Strike Fighter (JSF) were written in the mid-1990s. There are no signs that the raw RCS of the F-22 or JSF is much smaller than that of the F-117. The goals were to improve aircraft performance and maintainability, neither of which (to put it very mildly, indeed) was the F-117’s long suit. If you want a very low RCS in VHF, you need to lose the tails, which is why the B-2 is a flying wing.
It wasn’t hard for the Russians to assess the JSF’s stealth performance. By 1995, everyone knew that shape was the major driver of RCS, with materials being used to control local scattering phenomena. As the JSF’s target service entry date arrived, so did the Russian answer, and it was on display at the MAKS air show, held in Moscow in August.
The 55Zh6ME radar complex addresses many of the limitations of the old VHF radars. Although you see three radars—stepping down from VHF (metric) to L-band (decametric) and S-band (centimetric)—the Russians call them modules of an integrated radar system. Each unit is fitted with the Orientir satellite-navigation system, which provides a very accurate location and north reference. That should make it possible to provide sensor fusion—ensuring that when two or more of the radar units detect a target, it will show up as one in the control center.
Related Links:
- When Lockheed Martin Won The JSF Award (2001) | From The Archives
- Defense.gov News Article: Lockheed-Martin Team Wins Joint Strike Fighter Competition
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