YJ-27 anti-stealth radar

tphuang said:

more on JY-27 type of radar. This is from air force engineering university newspaper regarding the usage of JY-27
- basically it seems like the idea is to use the wideband radar like JY-27 to guide the missiles to within 15km of the stealth target and hope that the missile can lock onto the stealth target using impulse? (maybe CW) seeker.

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What they seem to be suggesting here is a bit of a stretch really. Large volume, long frequency radars do not update fast enough even to suit the needs of midphase inertial guidance of SAMs and AAMs. That's why even AMRAAM has to use the plane's engaged TWS modes for midphase guidance, and not the plane's RWS modes, which provide volume search. Even the best active radar homing air to air missiles cannot rely on a broad aimpoint due to the speed and evasability of the airborne target. Antiship missiles use ARH principle and can use a broad aim point, but then ships are a lot bigger and slower than a jet aircraft.

Like I said earlier, these large volume search radars can be used to que a more precise faster tracking tracking radar that is better suited for SAM midphase updates.

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Article is written like a marketing brochure for the F-22, with a vested interest for the F-22 and quoting an engineer with a vested interest. Hardly an objective source.

There are many ways to increase detection instead of just relying on sheer power alone.

1. Tightening the beam, so you have less energy loss on sidelobs. Focusing energy greatly magnifies the signal. This is where stuff like AESA/PESA coming in.

2. Increasing the dwell time of the signal. You increase the amount of energy received on the target by increasing the duration of the pulse.

2A. Techniques like CWI or Continious Wave Illumination provides for infinite duration and infinite pulse repetition.

3. Increasing the number of pulses also increase the energy received on the target. See 2A again.

4. Adding a short burst or "chirp" within the pulse increases the signal gain of the pulse.

5. Increasing the signal receptivity of the array. Many ways to do this.
5A. Increase the array size.
5B. Improving the sensitivity of the radio frequency processors on the array. AESA allows you to make each T/R module into an RF processor by itself, instead of attaching RF processors into a dieelectric or ferrite plate. Here the signal is received directly into the RF processor without any intermediary material.

6. Improving the way to process weak signals.
6A. More powerful computing processors.
6B. More powerful Digital Signal Processors.
6C. SAW devices which will compress and amplify weak signals.


As for the bistatic portion, there is something also called passive coherent location. It has no need for two stations both receiving and transmitting, rather, just one reciever and one transmitter. All the receiver needs to know is the location of the transmitter, original frequency of the emission and of course, time of the emission, which is the trickier part.

The use of non radar sensor means also has much promise.

The chances of one missile, even if directed within 15km, may be low. But stealth aircraft are high value targets, it would not surprise me to attack it with a barrage of missiles in a search pattern. And if one missile detects it, the rest can be directed to follow on. It would be like a "flak" attack. But even damaging the stealth aircraft slightly may increase its reflectivity dramatically. I wouldn't be surprised if someone has thought about RCS increasing shrapnel.

RedMercury said:

The chances of one missile, even if directed within 15km, may be low. But stealth aircraft are high value targets, it would not surprise me to attack it with a barrage of missiles in a search pattern. And if one missile detects it, the rest can be directed to follow on. It would be like a "flak" attack. But even damaging the stealth aircraft slightly may increase its reflectivity dramatically. I wouldn't be surprised if someone has thought about RCS increasing shrapnel.

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No, no one would do that. Even with high value targets. Using up too many missiles leaves you vulnerable to protect the high value target on your side. No missile in the world has the networking behavior you described and not even in the US.

If I want to create a loiter net of detection, I would do it with UCAVs, which will just direct the missiles.

Cueing LOAL IIR missiles is still a great idea though. While data from just one radar might very well be of little use, having a larger network of integrated sensors, illuminating the target from various directions would provide for a more precise synthetic picture, made out of many overlapping single radar pictures, perhaps precise enough to warrant a kill here and there.

Without changing direction at a right moment, i actually don't see how even a 15 km distance is not good enough for such a kill. And the stealth plane must know just when to start jiggling. Or it must change direction all the time close to/over enemy territory, which not only compromises its stealth to some degree, but wastes quite a bit of fuel.

In any case, point is to move away from "one radar cues one missile" system to "whole defense network, made out of multiple (hundreds?) of sensors, cues one missile".

but guys, aren't you all forgetting about the placement of radars?
'stealth' aircraft like the b-2 and the f-117 are not completely immune to SAM detection. thats why every single sortie of these aircraft are still carefully planned to avoid flying over, or close to, sam sites. stealth reduces the effectiveness of SAM, not eliminating it. remember when that f-117 got shot down in serbia? the SAM site commander was using out dated sa-3's, which had no 'anti stealth' capability at all. he shot down the f-117 because he was able to predict the flight path of it and therefore, move his same site close to that location. he was able to guess the flight path because nato used that same rout e more than once. he did not fire a barrage, but rather, his missiles did have a lock on the plane.
this just shows the importance of intelligence (information) in countering stealth. therefore, the YJ-27 could prove itself useful by directing sam sites close to an enemy fighter's predicted flight path.

Some points.

IIR can have a much greater than 15km. It would most certainly help speed up the lock if something can que the IIR seeker into the right direction of the target so it can focus on it.

The shotdown of the F-117 was done by an SA-3 missile. An electro optical guidance package was offered as a upgrade to this missile, and it may have been that, which could have given the lock. The SA-3 is a point defense missile though, so you still need to put it on the path of the interdictor. While most modern SAMs are radar guided, some SAMs offer backup electro optical guidance, such as the Croatale and their Chinese counterparts, the HQ-7.

Stealth differs from aspect to aspect. A plane that is stealthy when viewed head on, may not be as stealthy from the bottom side. The VLO figures from aspect to aspect is highly confidential.

Do note that designs like the F-22 do realize some vulnerability to SAMs and optical sensors and have already compensated for that. That's where the supercruise and the ability to fly at very high altitude comes in. Hence why I think why this system of using YJ-27 and a SAM network is far from enough. It is a pipedream if you think that can stop an F-22 with this kind of equipment alone.

while i won't speculate on just what will 'stop a f22' i must say i don't really see much difference between detecting and shooting down a plane that flies at 12 000 meters and one that cruises at 18 000 meters. Increased distance from the radar is negligable and while the added altitude would require more fuel for the missile, it still doesn't mean its anything more than a small jump in required performance, perfectly within reach of SAMs deployed today.

One also has to note that, depending on the mission profile, even f22 won't really be able to afford to supercruise all the time since that still uses quite a bit of more fuel than regular subsonic cruise.

Basically, IF your sensor network can give you a location of the enemy, updated every second or so, It would give you high enough chance to intercept that enemy, be it even a mig25 on afterburners. In the end, one's goal can't be to 'stop the enemy' but just to kill enough of them on a regular basis to make the enemy commanders rethink the idea of sending more. With precious little f22s, even one lost raptor in every ten sorties would be quite a blow to USAF.

Basically, what i'm saying is this: It doesn't matter if you try to down a raptor by fighter interceptors or SAMs - you'll still have little chance to succeed. What matters is dettecton and tracking. If you succeed in that, it doesn't matter if you send out 30 interceptors or fire off 30 SAMs. (i'd opt for the latter, as it'd be cheaper, since some interceptors would inevitably be lost)

Well, with all this stealth things, detecting range, and therefore tracking time is a very important variable to consider.
A (frontal aspect) VLO plane that is detected rather close to the site, will spend much less time in jeopardy. Once you detect something, you need to accurately track it (wich is much more difficult than to just detect the presence and takes time). So, there are chances that the VLO plane may pass the SAM launcher before the missile reaches it. Now a missile that has to chase a supercruising airplane at 18k m hasa very hard time scoring a kill.
In this regards a high density sensor network (IADS) would probably be the best option.
With forthcoming stealth technologies that focused mainly on RCS reduction and evolving modern IRST, optical tracking and cueing - perhaps afther detection through long wave EWRs - becomes more and more important.
The Python 5, IR Mica, and respective R-27 versions are steps in that direction.

instead of stopping the F22, why not just go missile war and blow each other runway into bits before the F22 even get to the target? the F22 is an effective platform, but everything else that support it may not be as up to the job. asymetric warfare is the only way to defeat US superiority.