British attempt to defeat Chinese counter-stealth radar

[Martian2]

In the beginning, the attacker invented an aircraft to bomb the defender.

The defender invented radar and a surface-to-air missile to shoot down the attacking aircraft.

The attacker responded by building stealth aircraft, which is stealthy in X-band and upper S-band.

The defender replied with L-band and VHF (ie. very high frequency) radars to detect stealth aircraft.

The Chinese KJ-2000 AWACS has L-band radar. The Chinese Aegis Type 052C/D destroyers have a VHF radar.

Now, the British Taranis looks like it is designed to defeat VHF counter-stealth radar.

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Broadband Stealth May Drive Taranis Design | AviationWeek

"Broadband Stealth May Drive Taranis Design
By Bill Sweetman
Source: Aviation Week & Space Technology
February 17, 2014

Credit: BAE Systems

BAE Systems' Taranis unmanned combat air system demonstrator is designed to defeat new counter-stealth radars, and may use thrust vectoring as a primary means of flight control and an innovative high-precision, passive navigation and guidance system, an AW&ST analysis indicates.

Taranis is a blended wing-body shape with no tail surfaces, like most UCAS designs for wide-band, all-aspect stealth. It has a triangular top-mounted inlet and 2-D V-shaped exhaust nozzle. The underside is flat, with visible outlines representing weapon-bay doors. Panels under the leading edge point to provision for a dual-antenna radar like a smaller version of that fitted to the B-2 bomber. The demonstrator may be designed so that functional weapon bays and sensors can be installed for a follow-on program.

The Rolls-Royce Adour engine is mounted low in the center fuselage, behind a serpentine duct. Two small doors are visible on either side of the raised centerbody, and are likely to be auxiliary inlets used at low speeds. The weapon-bay outlines are on either side of the engine and the forward-retracting main landing gears are outboard of the weapon bays. The demonstrator's gear comes from the Saab Gripen.

The wing leading edges are highly swept to reduce head-on radar cross-section at all wavelengths. The double-V trailing edge is swept more acutely than on most blended wing-body UCAS designs. Unlike the Northrop Grumman X-47B or the Dassault-led Neuron, there are no short-chord wing sections or short edges: The shortest edge is more than 11 ft. long.

This most likely indicates Taranis is designed to avoid detection by very high frequency (VHF) early warning radars such as those being developed by Russia and China as counter-stealth systems (AW&ST Sept. 2, 2013, p. 28). VHF radars can detect some stealth shapes with wing and tail surfaces close in size to their meter-range wavelengths. When that happens, radar scattering is driven by “resonant” phenomena not affected by the target's shape.

Taranis's flight controls are intriguing. There are two large elevon surfaces on the trailing edge, with deep “cat-eye” cut-outs at both ends: These prevent formation of right-angle shapes when the elevons move, and are large because the surfaces are thick. Outboard of the elevons are upper and lower “inlay” control surfaces, set into the wing surface.

The elevons will provide pitch and roll force. The inlay surfaces can act as roll spoilers and speedbrakes, and differentially for yaw control. (Similar surfaces were used on the upper side of the X-47B.) But the inlay surfaces are non-stealthy when open, so they must mainly be used at low speeds, including take-off and landing. The one-piece elevons cannot provide yaw input that is independent of pitch or roll. There is no visible source of yaw control, which points to the use of thrust vectoring.

In 2010, BAE teamed with two British universities to build a small UAV called Demon with fluidic vectoring—using air injection inside the exhaust to vector the thrust, with no moving parts externally or in the exhaust stream—as part of a flight-control system with no moving surfaces. A Rolls-Royce patent filed in the U.K. in 2005 outlines a fluidic vectoring system designed to generate yawing moments in a high-aspect-ratio 2-D nozzle.

The navigation and guidance system for Taranis, perhaps not yet installed, very probably uses an advanced concept called simultaneous localization and mapping (Slam). BAE Systems Australia has been developing a highly autonomous Slam-based system and is responsible for the Taranis navigation and guidance gear, which it refuses to discuss (AW&ST April 1, 2013, p. 24).

Slam is suited to a stealth aircraft because it can use passive sensors—day video, IR or passive RF. Nor does it rely on a sometimes inaccurate terrain database.

Taranis is a subscale demonstrator. However, a 25% scale-up would result in an aircraft of almost twice the weight, so it is probably close in size to an operational follow-on."

 

[tranquilium]

I am pretty sure British's aim is not at China, considering the two countries have very limited strategic conflict.

 

[Martian2]

China will react to British Taranis

Taranis is a subscale demonstrator. However, a 25% scale-up would result in an aircraft of almost twice the weight, so it is probably close in size to an operational follow-on.

It's a British sub-scale prototype. If implemented correctly, it should render VHF radar useless against the Taranis. However, there might be a compromise in aircraft performance due to the lack of meter-length tail control surfaces.

The Taranis has to be careful and stay outside the range of a Chinese KJ-2000 AWACS with L-band radar. If the Taranis is detectable in lower S-band or C-band, it will have to stay away from ground-based radar stations too.

The Taranis may be visible on HF (ie. high frequency) radar. HF radar should be able to detect the 11-foot Taranis control surfaces. Also, the entire Taranis vehicle should resonate at radar wavelength on the scale of the Taranis' length.

Obviously, the Chinese will secretly build their own version of the Taranis to defeat VHF radar and test their other radar spectrums against the Chinese Taranis.

 

[bolo]

I am pretty sure British's aim is not at China, considering the two countries have very limited strategic conflict.

Well yes and no. The aim is to counter anything with high VHF frequency that is on Chinese awacs and destroyers.

 

[Martian2]

C-band radar, F-22 vulnerabilities, and RQ-170 stealth UAV

There are three separate points that I want to make.

1. The American Patriot anti-missile system uses C-band radar. It is widely known that the F-22 stealth aircraft is stealthy only in X-band and upper S-band. It would be interesting to illuminate a F-22 with C-band radar and see what happens.

Patriot Missile Long-Range Air-Defence System, United States of America | Army Technology

Trailer-mounted Raytheon MPQ-53 C-Band tracking radar for Patriot missile system. The trailer-mounted Raytheon MPQ-53 C-Band tracking radar, is capable of identifying 100 targets.

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We have the following common radar bands.

X-band: Fire-control radar for jet aircraft
C-band: Used by American Patriot Missile System
S-band: Present on Chinese Aegis Type 052C/D destroyers and American Aegis destroyers
L-band: Present on Chinese KJ-2000 AWACS
VHF: Present on Chinese Aegis Type 052C/D destroyers
HF: Chinese over-the-horizon radars use HF (ie. high frequency) band
(See High-frequency over-the-horizon radar and ionospheric backscatter studies in China | ResearchGate)

We know stealth aircraft can be seen on L-band and VHF. Stealth aircraft should also be visible in HF, because the length or width of the aircraft should resonate at HF half-wavelength.

I do not know if C-band or lower S-band can see stealth aircraft or at what range.

The point is that stealth aircraft is not that stealthy. It depends on the radar band that is being used and at what range. Since China is a highly-industrialized nation that uses all radar bands, we can conclude that stealth aircraft is not stealthy to the full spectrum of Chinese radars.

2. Some people have suggested putting external conformal fuel tanks on the F-22 to extend its short combat radius. However, this is a bad idea for three reasons. Firstly, the F-22's external conformal fuel tanks will resonate at its own half-wavelength (e.g. length or width). Secondly, external fuel tanks violate the area rule. A radar illuminating an F-22 at a 3/4 angle will see a lot more area. This will light up the F-22 for bistatic or multistatic radar. Thirdly, the F-22 would lose a lot of its maneuverability with heavy external fuel tanks hung from its wings.

F-22 with drop tanks in transit to Kadena Air Base, Japan, from Langley Air Force Base, Virginia

3. How did Iran manage to capture the American RQ-170 stealth UAV? The RQ-170 flies at 50,000 feet and it's stealthy. How did Iran even know the RQ-170 is there?

Given the remarkably good shape of the captured RQ-170, an accidental crash looks unlikely. Also, it is standard American policy to bomb valuable crashed military equipment.

By excluding a crash, it suggests the American military was caught unaware when the Iranians took control (via GPS spoofing or other means) of the RQ-170.

This brings us back to the original mystery. How did Iran know the location of a high-flying RQ-170? I believe either Russia or China had a hand in locating and bringing down the RQ-170. Only those two countries have the technical skill and equipment. If what I suspect is true, it means the RQ-170 is not stealthy to Russia/China.

This still leaves unanswered whether a B-2 (which is far more expensive and stealthier) is visible to Russia/China. However, if the RQ-170 was located and intentionally brought down then American stealth is losing ground to Russian/Chinese radar and electronic expertise.

Iran Shows Downed Spy Drone as U.S. Assesses Technology Loss | BusinessWeek

 

[nangyale]

Maybe this explains how the Iranians were able to bring down RQ-170.

Russia Took Down a U.S. Drone Over Crimea

 

[bolo]

What are the chances of China detecting spy planes flying over its territory nowadays? Back then, the SR 71 supposedly flew over Russian and Chinese territory?

 

[terranMarine]

What are the chances of China detecting spy planes flying over its territory nowadays? Back then, the SR 71 supposedly flew over Russian and Chinese territory?

SR-71 is not a stealth plane, the Russians knew about the plane flying over Russia during the Cold War because their Mig-25 pilots were trying to take it down but couldn't maintain Mach 3. This is also why the Russians developed the Mig-31 which can maintain that speed. The Americans stopped sending the blackbirds over Russia because of this new threat and relied on their improved spy satellites.

The Russians claimed recently they had shot down an American drone, says enough about Russian capabilities. The US cannot send spy planes over Russia and China without getting destroyed and why should they when spy satellites can accomplish the task.

 

[Martian2]

F-35 can be seen by VHF, HF, S, L, and X-band radars

An F-35 can be detected by VHF radar due to resonance and Rayleigh scattering.

HF radar can see an F-35 by bouncing the signal off the ionosphere and detecting the F-35 from above.
S and L-band radars can see an F-35 from all angles except from the front.
X-band radar can see an F-35 from the side only.

In conclusion, digital radars with powerful digital signal processing can detect formerly stealthy aircraft.

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How stealthy is the F-35 | Defense Issues

"F-35s stealth

Radar stealth

F-35 was designed from the outset to be less stealthy against X-band radar than the F-22. But it has characteristics which will reduce stealth level even further. Both F-35 and F-22 are only stealthy against enemy radars that are horizontal or few degrees from horizontal. Due to lower inclination of surfaces from the horizontal, this “stealth area” for the F-35 is far less than F-22s; and as soon as F-35 maneuvers, it becomes instantly unstealthy unless maneuvers are done only by vertical tail surfaces, keeping aircraft completely level. F-35 also has many irregularities in its surface – there is bulge above left wing, presumably where the gun is located on the A version, as well as bulges below wing root, on weapons bays doors, below the engine and below the nose where IRST is located. These all help increase F-35s RCS when it maneuvers away from horizontal plane.

VHF radars are radars with wavelengths in 1-3 meter range. For this, it is important to understand two terms:
Rayleigh scattering region is region where wavelength is larger than shaping features of target or target itself. In that region, only thing that matters for RCS is actual physical size of target itself. Resonance occurs where shaping features are comparable in wavelength to radar, resulting in induced electrical charges over the skin of target, vastly increasing RCS.

F-35 in VHF band

As it can be seen, many F-35s shaping features are in either Rayleigh or resonance scattering region of VHF radars. Situation with early warning HF radars is even worse, as they not only have very long wavelengths, but also come from above after reflecting from the atmosphere. Situation is somewhat better with S and L band radars, but F-35s RCS against these is still far higher than against X band radars. Even against X-band radars, it is only stealthy (LO) from front and rear; against S-band radar, it is stealthy from narrow front aspect, while only limited reduction is achieved from direct front against L-band radar; this is in part thanks to nozzle design, whose segments act as Rayleigh or resonance reflectors in all bands with lower frequency than X band. Against ground-based X-band radars, its side RCS will likely be similar to that of conventional fighter.

When combined with lack of kinematic performance, it means that F-35 will be held back until F-22s and Growlers – or in European ventures, Rafales and Typhoons – have neutralized enemy air defenses. This removes only justification for all-aspect stealth."

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Assessing Joint Strike Fighter Defence Penetration Capabilities | Air Power Australia

[Red means a particular band of radar can see the F-35 from that direction.]

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Of Wargames, JSFs and Baby Seals (II) « Steeljaw Scribe

"In the realm of radar, it depends on the type (band) of radar encountered. The current generation’s capability is optimized against X-band tracking and guidance fire control systems. Less well understood will be its capability against the likes of much lower band radars, especially those deployed in the VHF band. This is an issue because the waveforms are large enough in the lower frequencies to overcome many of the LO measures deployed. In times past, this was an acceptable situation because the systems then, while possibly detecting an LO aircraft, did not have a fire control-level of accuracy (ask an E-2 NFO sometime about radar bananas…). Primarily it is because of the design of low frequency antennas and the distance of the object from the radiating source, it would not be unusual to get a return that would measure out at a couple of miles in azimuth and range. Yes – there is “something” there, but absent a fire control system, there isn’t anything kinetically that can be done about it.

That is, until the advent of an AESA variant of VHF radar (1L119 Nebo SVU), which the Russians are deploying to support their S-300 SAM systems.

[Russian VHF radars. It is a fully digital AESA with precision 3D capability, with accuracy rivaling S-band missile battery acquisition radars. (Caption source: Dr. Carlo Kopp at Russian VHF counter stealth radars proliferate | Air Power Australia)]

Why VHF radar? Recall the relationship between LO/VLO and radar waves – the smaller the wavelength (higher frequency) the “easier” it is to develop/deploy LO/VLO countermeasures. Go in the other direction, however, and eventually just the sheer size of the aircraft will enable detection by the radar. The following image (via www.AUSAirpower.net) is germane –

'For instance, let us consider the F-35 JSF in the 2 metre band favoured by Russian VHF radar designers. From a planform shaping perspective, it is immediately apparent that the nose, inlets, nozzle and junctions between fuselage, wing and stabs will present as Raleigh regime scattering centres, since the shaping features are smaller than a wavelength. Most of the straight edges are 1.5 to two wavelengths in size, putting them firmly in the resonance regime of scattering. Size simply precludes the possibility that this airframe can neatly reflect impinging 2 metre band radiation away in a well controlled fashion.

The only viable mechanism for reducing the VHF band signature is therefore in materials, especially materials which can strongly attenuate the induced electrical currents in the skins and leading edges. The physics of the skin effect show that the skin depth is minimised by materials which have strong magnetic properties. The unclassified literature is replete with magnetic absorber materials which have reasonable attenuation performance at VHF band, but are very dense, and materials which require significant depth to be effective if lightweight. The problem the JSF has is that it cannot easily carry many hundreds of pounds of low band absorber materials in an airframe with borderline aerodynamic performance. Some technologies, such as laminated photonic surface structures might be viable for skins, but the experimental work shows best effect in the decimetric and centimetric bands. Thickness again becomes an issue.

The reality is that in conventional decimetric to centimetric radar band low observable design, shaping accounts for the first 10 to 100 fold reduction in signature, and materials are used to gain the remainder of the signature reduction effect. In the VHF band shaping in fighter sized aircraft is largely ineffective, requiring absorbent materials with 10 to 100 fold better performance than materials currently in use. In the world of materials, getting twice the performance out of a new material is considered good, getting fivefold performance exceptional, and getting 100 fold better performance requires some fundamental breakthrough in physics.'"

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totallynotabrony - FIMFiction.net

"Okay, so now you’re up and operating. What else should you keep in mind? The weather is a big factor. Generally, clear days are better for radio. Plus, there’s this nifty thing called the ionosphere. It’s a region of the upper atmosphere, from about 85 km (53 mi) to 600 km (370 mi) altitude. Some radio waves (called skywaves) can bounce off it, thereby going around the world. It takes a lot of math and smart people to calculate this stuff. Everyone wants to extend their signal over the horizon.

High Frequency (HF) is generally the highest signals that can take advantage of bouncing. This is why AM radio, at MF, has historically been long-ranged, especially at night when the lack of sun causes changes in the ionosphere. Higher frequencies just punch through the ionosphere into space instead of bouncing. Lower signals, like ELF, can curve with the ground – 'ground waves.'"

 

[shuttler]

Brits are the US's closest ally
Brits are a member of NATO
Brits have deployed over 300 staff in the small consulate of HK
Brits have rebuilt their consulate building in HK upon the handover
Brits have many remnants in HK after the handover (on top of the 300)
Brits votings are an extension of the votings of USA in all UN resolutions. We are on the opposite side of the fence, many times sitting alongside Russia
China supports Argentina in the Melvinas (Falkland) island claims
Brits support do$$ar lama, and covertly for the independence of Taiwan
Brits gifted our land to india and all those hideous jazz

I subscribe to the claim that British attempt to defeat Chinese counter-stealth radar without reservation

 

[chhota bheem]

i thought US and Russia are light years ahead of china in technology,the whole article sounds like as if China and Russia are on the same level.

 

[Martian2]

i thought US and Russia are light years ahead of china in technology,the whole article sounds like as if China and Russia are on the same level.

China's Type 517M digital VHF AESA radar and superior HQ-9 digital signal processing (DSP)

China has its own digital VHF AESA radar such as the Type 517M, which can be seen on the Type 052C Chinese Aegis destroyer.

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China's HQ-9 is the equivalent of Russia's S-300 SAM. However, the Chinese HQ-9 has more advanced signal processing.

HQ-9 and HQ-12 SAM System Battery Radars | Air Power Australia

Excerpt: "Stills captured from a January, 2010, CCTV7 broadcast discussing the HQ-9 SAM system in operation, show a number of operator consoles in vans used with the system. Notable is the use of state-of-the-art AMCLD COTS display technology, and modern software based synthetic displays and mode selection. This is quite distinct from the CRT technology used in Russian built S-300PMU/PMU1 battery components."

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Compare the advanced Chinese digital displays and functions for the HQ-9 (see above) with the Russian S-300 command center below using old CRT technology. The picture is a snapshot from the video "S-300 missile destroys 'enemy fighter' at Ashuluk."