PeeDIndeed they have 64N6 BIG BIRD (S/X-Band ) , 96L6E ( L band ) and 30N6 Tomb Stone radar ( X band ) operating for S-300PMU2.
Considering most of their AD system are reverse engineered modified 70’s system , they might need something like BUK-M2 to meet lower/medium end of threat
A coincidence that you talk about Buk-M2. Iranian certainly like its concept and have developed a own design (a more lean one):
Their tech is certainly not as 70’s anymore and I don’t expect more imports of air defense systems after the S-300PMU2.
PeeD@garryA
A soft turn will not have you get into the deflection angle of stealth aircraft. You yourself described it as a ring around the asset. The missiles need to take a very steep dive/turn
The turn is soft, meaning it has long duration/radius to reach the intended attack aspect/direction, this safes energy as potential energy is is transferred to kinetic (your hard U-turn wording implies otherwise). A pop-up maneuver after the dive to attack from below would make a harder turn necessary.
Iam struggle to imagine how the gimballed seeker has anything to do with the RCS spike here.
A gimballed seeker can re-scan if a spike is getting weaker and catch other amplitudes which are within reach.
Assuming that the spike either turn toward the radar or the missiles but what if it isn’t ?
Then we have the worst case where data from a fused sensor such as a Nebo-SVU must be used and the SAM’s heavy warhead. However the Grave-/Tombstone are brute force systems, I stated performance values, one is 45km for a 0,001m² target. Hence there are reasonable chances that a change of aspect, forced by a bi-static SAM would be sufficient for a spike return.
Let say missiles moving at Mach 5, you made a steep maneuver that reduced the speed to Mach 3, now the thicker air at low altitude will reduce that speed even further down to Mach 2 and lower. If you consume energy for unneccesary maneuver then you have less to fight against drag at low altitude. Eventhough, drag at lower speed is lower, your net energy/ speed would still be reduced if you made a maneuver
You said it; drag decreases as speed decreases. Coming down from 27km to 17km is 10km where you have constant acceleration by gravitation (constant) and a stronger deceleration by drag (proportional). You can start a soft maneuvering from long distance, depleting energy but also produce less drag due to speed reduction. To put it simply by another example: Do a hard turn at 27km (less drag), dive down and have less drag losses due to decreased speed by the turn with the same g acceleration. You end up with much less energy loss for the maneuver than doing it at 17km right at the target. Furthermore if you fear that kinematics could become a problem, do the interception at 150km instead of 250km with more energy reserves (more realistic anyway due to the problems with VLO asset illumination). Kinematics is the least problem with the concept.
That just a guess , we dont have enough information to conclude how much effect shape has and how much effect RAM and RAS has, it depends alot on frequency too
Higher performancer RAM are thicker ( can be a few mm thick) so may not be suitable for conventional aircraft that wasn’t designed with them from the out set, some RAM such as fibermat can be used as structure too so they need to be intergrated from start. Moreover, there are place that not sutable for RAM such as engine fan blade, missiles seeker , missiles fin( corner reflector). Conventional asset also lack edge treatment so they also suffer more from surfacewave scattering. Band width of shaping may be wider too
Agreed, we don’t know about RAM effect. I tend to go of -10 DBSM at the moment.
All Stealth aircraft have aglied edge, so it is likely that their spike are concentrated in very narrow angle instead of evenly distributed.
A discrete number of narrow angle spikes distributed in the ring, some stronger in amplitude some weaker. I guess the proposed concept would work less well against a low number of discrete surfaces VLO design as the F-117, tough.
That the whole point of stealth design is it not ?, if radar/missiles can easily detect energy even from low spike scattering then what the point of deflect radar wave toward some specific angle ?
When a VLO design deflects the waves into a controlled angle/direction, away, it wont be received by the usual monostatic radar, mission accomplished. But how about the receiver being flexible to position itself where it wants (bi-static)? Deflected low spikes are useful for the seeker because they are still stronger in a VLO design than the evenly distributed energy on a conventional design (assumed to have the same RAM treatment).
The shaping can easily responsible for 25-35 dB reduction, RAM take care of another 15-20 dB reduction in RCS
Sounds reasonable even if we approach the mystic pea size of 0,000003m² RCS for F-35 at -55 DBSM. I take your conservative number of -15 DBSM for RAM. My data shows that the S-400 Gravestone radar would track a -15 DBSM target at ~100km. Hence put simplified, the deflection scattering after RAM is trackable at 100km for the radar itself, better for the closer positioned seeker. The ~-30 DBSM due to shaping is not going into the calculation because the concept is intended to neglect that effect.
Your explaination is very vague and doesn’t seem to address the question.
Say you have a massive VHF radar, your beam width is about 2 degrees, that is about few km of space at long distance. You will get return from both the chaff and the aircraft at the same time ( in fact even gound return if aircraft is low enough) , so how to you distingush without Doppler shift ?.
radar and seeker vector is irrelevance in this case IMHO
You may underestimate the resolution and ECM/chaff performance of modern VHF assets such as the Nebo-SVU.
What I was talking about was a method to determine the degree of distortion of doppler shift you mentioned due to the side aspect engagment. I would determine the vetors of target and seeker and calculate the correct doppler shift for range/MTI purposes. This corrections would be applied to the distorted seeker data and the true doppler shift would be the result. I’m not a radar designer its just a simple solution to a potential problem you proposed.
Wide illumination beam is a horrible horrible idea, not only that the energy level would reduced significantly but you also reduce the accuracy of your missiles at the same time.
Of course a wide beam is bad for a illumination radar, did I say otherwise? However I disagree about that accuracy part, but that’s off-topic.
PeeDWell that CAFRAD radar system sounds indeed impressive and technologically on pair with some of the S-400s radar components.
Lets see when its produced, articles state that development is completed in 2015 while its about to be deployed in 2023? A little ahead of schedule and a quite huge jump for Turkey to a SPY-1 level system.
PeeD@garryA
A soft turn is a turn with very small angle, if you want to get into reflection spike of VLO aircraft, a shalow dive is not sufficient, and what if the aircraft roll ?
A soft turn that only consumes excess potential energy as described, not a hard U-turn. Aircraft roll will change the spikes of deflection, fluctuations. The gimballed seeker would realign if RF gets too low, or SAGG guidance would override if changed aspect creates a echo on the radar which is stronger than that of the SARH seeker.
You cannot perform a maneuver without losing any energy if you have no thrust left. Any meneuver that attempt to change missiles direction will also present missiles side body to the air flow, thus cause more drag than normal. More drag mean losing more speed.
You will always lose energy if you maneuver. Thrust and potential energy can compensate that loss. You talk about drag and should be aware that a diving mach 5 SAM at 25km would slow down to something like mach 3 down to sea level, just due to drag (or you consumes it for maneuvering and slow down =less drag losses).
RAM can absorb alot more than 30% of radar energy. In X band some RAM has absorb rating around 20-30 dB which is around 99-99.9%.
Pardon, my fault, I wanted to say for total stealth effect, the RCS reduction, is only for at best 1/3 due to RAM, rest is deflection scattering. However I express my doubts that operational feasible RAM coating could create a -30 DBSM reduction, even in x-band (it would mean a 10m² head-on F-15 would get a RCS of 0,01m², it would become a F-117 class VLO asset).
The reflection in the ring is not evenly distribulted, you have some high RCS spike , you also have some low RCS spike , and those points are also on different plane. Imagine you need to position your missiles at red or black circle
Bear in mind that by VLO deflection, scattering is concentrated in are more confined space than a conventional design (free to go in any direction). Furthermore I reject the idea that spikes are necessary for a home on the target, lower amplitude scattering could be sufficient, more so due to the mentioned concentration effect. At least I don’t know how you determined that spikes are necessary, not knowing the illumination RF energy levels and seeker sensitivity. You may think that after a RAM reduction of -30 DBSM, the deflection scattering is very weak, so that spikes are necessary?
But where do you get that 10% value from while the RCS reduction effect of both shape and RAM can be much bigger than 10 dB, especially at X band
The 10% deflected RF energy is too high? Your reduction value of 99,9% would mean that 0,1% of the RF energy would be deflected. I don’t expect such a drastic effect by RAM and think that deflection is responsible for the biggest part.
The point was rather about what amount of RF energy is necessary for the SARH seeker to be able to home on target.
What ? , how ? the missiles literally would be outside of the lobes if the aircraft roll slightly
Outside of a spike. The mid-level background scattering could be sufficient, and increased due to the mentioned concentration effect. Your spikes would be necessary if RAM would create a -30 DBSM reduction, agreed.
VHF resolution cell is too big so it wont be able to distingush between the aircraft and chaff that very close to it.
X band can’t see the F-35
I cant see the relation with missiles vector either
Moreover, how wide you want the illumination beam to be ?
VHF resolution is sufficient to determine the vector and used, in relation to radar and seeker vector, to correct the doppler shift. Illumination beam is very wide for brute force S-400 like systems at those long ranges, certainly larger than the VHF resolution.
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@Ozair
And this is the problem. The following journal article http://www.scienpress.com/Upload/JCM/Vol%204_1_9.pdf takes a worst case F-35 RCS assessment and calculates the probable detection values for common systems. Given the X-Band nature of the S-300 30N6E1 we get, for the average F-35 RCS, just a 7nm detection range. How likely then are active seekers, let alone a SARH seeker, that is a 50th the size, going to get reflections of a minuscule target return, expected to fare?
The data basis for the author is very weak. His whole analysis becomes worthless with the range/RCS assumptions he made for the Tombstone and Big Bird radars. At least in 2016, if not earlier we got official Russian data on those.
7nm for a 10.000 element high power PESA (30N6E)? With his F-35 RCS number and the new data, I get 45km in my calculations.
As for your question: You have not read the thread, its not about a conventional engagement. Its about a proposed bi-static operation mode.
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@SpudmanWP
Neither the Low-band or Bistatic (trip-wire) systems can give you enough accuracy to pass along to the illuminator.
How advanced are Russians? Can the create a aperture that creates a illumination lobe that is so precise that its below VHF-band resolution at engagement ranges of 200km? I have great doubts that something like that is technically possible. Even a P-18 class resolution would be smaller than the lobe width at target, not to talk about something like the Nebo-SVU.
Since it’s an illuminator, it has to be constantly on target. It knows this by getting feedback from its own signals. A VLO target will not return enough of the illuminator’s own signal in order to let the illuminator know it’s on target. You have already conceded this point as this is why you proposed SARH.
It might has to illuminate the target for the last 20 sec of the engagement, possibly less. The illuminating radar would only get a return if a “bad” face of the VLO asset is exposed to it due to maneuvering we talk about. Bear in mind that this is not any radar but a brute force 10.000 element large aperture x-band PESA which detects a 0,01 m² RCS target at ~75km.
Who said the Russians are not already using this concept?
Who said they are?
I didn’t. I just proposed a concept.
PeeD@garryA
Almost all BVR missiles follow a ballistic arcs, the potential energy is not as much as you think, and they are not free either. Missiles basically trade fuel for potential energy when they climb in boost phase.
Even long range SAM would coat in terminal phase, and with high weight and big size they do consume a significant amount of enrgy to do a U turn. Normally the excess energy will be used to help missiles intercept the target that change direction, however, in your case you waited it on a U turn maneuver.
I think its enough for a rather soft positioning turn. See, these are high velocity missiles with dual pulse/sustainer motor, having something like Mach 4 or 5 during end of coast phase, entering terminal. During the terminal dive they initially gain velocity, but as air becomes denser this gain stops and the potential energy starts to heat up the missile (drag) and slowly decelerate it. So instead of heating up the missiles nose, aerodynamic control fins can decelerate the missile by maneuvering. Hence there are even good chances that no net energy will be lost at all during the positioning maneuver.
That hard to say, different RAM operate differently , but the absorbing capabilities could be extremely high depend on the frequency
( 3 dB is about 50% , 10 dB is about 90% ..etc )
We are dealing with X-band here, a very good band for RAM effectiveness. Subtract the RAM absorbing effect from the total RF illumination on target and you get the deflected RF energy. For adverse conditions I guess you agree that RAM will never be able to absorb 1/3 of that total RF illumination energy on target. The rest will be deflection and this is what the bi-static SARH has to work with.
Iam not entirely sure what are you trying to say by ” torus position “. As in a ring in horizontal plane or azimuth plane ??
Generally the location of high RCS spike, would be slightly toward the 30-35 degrees from the nose and to the side, kinda like the butterfly, but they dont just cover the whole area like when you look at the photo top down. You have to imagine the 3D image of them.They are like many spike on a hedgehog. To get your missiles in position is a similar job. a slight change in direction and the high RCS spike isn’t there anymore
The rotation axis of the ring will always point towards the illumination radar with the VLO freely in the center of the ring. Then changes of aspect of the VLO asset will create fluctuations as some faces deflect energy better away from the ring area than others (as you said in the water tube example). However overall and general deflection scattering pattern will be somewhere in the ring and from there expand outwards.
Also bear in mind that its not discrete high energy spikes. The F-117 might would create such spikes but modern VLO assets have high number of deflection surfaces/geometries. Hence the deflected RF energy will be quite evenly distributed. There are RCS spikes which can suddenly appear on the radar when a less optimized face is exposed to it, but that’s not what we talk about in the context of deflection. The scattering at the deflection angle is expected to be just like that of a conventional fighter (minus RAM).
where is that 10% number came from and how do you know if it enough or not ?
Just a simple comparison, knowing the RF energy losses relative to distance and systems such as the S-200.
The S-200 sits on its launcher when its illumination radar starts to paint a fighter sized target at 150-200km. Still on the ground its missile seeker receives the reflections and locks on target before launch. Now we don’t have 200km distance but 20-30km at best and when taking into account non-linear (^4) energy/range relation we can very well assume that under adverse conditions 10% of RF illumination energy would be sufficient to establish a lock at 20km instead of 200km. For adverse condition consideration I didn’t even take into account that the total travailing range of RF energy for S-200 is 200km x 2 = 400km, while for the S-400 its 250km + 20km = 260km, again not taking into account closure of target during engagement period. Under real conditions much less than 10% would be sufficient if you ask me.
The gimbal seeker would be useless if the reflection lobes doesn’t point at the missiles position at all.
The bi-static receiving position is designed to be in the direction of deflection lobes and the gimballed seeker will help it catch the strongest ones.
As i understand it ,basically, you want to rely on a VHF radar ( say NEBO SVU ) to get a rough position of target, then use another radar to illuminate that space.Then guess the location of the reflection lobes. Then launch a missiles toward the target. The missile then do a U turn to get in the reflection lobe.
The VHF radar wont help your missiles distingush the chaff or the airframe simply because its resolution cell is too big for that
The reflection from illumination radar wouldn’t help much because of the low Doppler shift due to radical velocity of the aircraft in respect to radar.
So iam not quite sure what MTI method do you propose here.
Roughly, some remarks:
– The deflection lobes are not random and partially dictated by the position of the illumination radar, relative to the target.
– No U-turn but a softer turn with less direction change, using of potential energy.
– The Tombstone high Resolution X-band beside sensor fused S- and VHF band radars (Big Bird and Nebo-SVU) will distinguish between chaff as well as the SAGG picture of the SAM seeker
For MTI I get the VLO asset’s vector via VHF band, missile vector via x-band engagement radar (radar position/vector is also known), calculate the correction factor for the misleading lower doppler shift.
@SpudmanWP
Low-band radars do not have enough accuracy to get a decent fix on a fighter, let alone a VLO fighter. This is why they are delegated to “trip-wire” types of systems that have a secondary high-band illumination radar.
Yes we assume that they don’t have sufficient accuracy, only provide vector and the position in space for the illumination radar. Trip-wire type Bi-/Multi-static systems like the Russian Barrier system is another way to get coarse location of VLO assets for the bi-static engagement method proposed here.
Missiles are too to have an effective low-band SARH seeker. There is a reason why the main low-band radar transceivers have their elements spread far apart.
Too small, right. We are talking about X-band engagement radar and X-band SARH seeker here.
I meant on top of all of the other issues (radar band poorly optimized to track target, missile seeker poorly optimized for tracking in a low-band, etc)
No, not poorly. The concept is about engaging the VLO asset in a way in which it behaves/reflects like a convention fighter (minus RAM losses).
The F-35 will be tracking the missile as it gains altitude and can change course long before the missile gets into a position where it can lock onto the VLO F-35 give #1-3 above.
The strongest indication that this will not work is that despite SARH being well know to the Russians, despite SARH being much cheaper than active homing, and despite them knowing that they will have to fight VLO objects (F-117, B-2, F-22, F-25, Cms, etc) that they have chosen not to do this.
Expect the missile to be launched when the F-35 is within no-escape zone.
Who said the Russians are not already using this concept? As said in the first post, the strange notion of Russians to stick to SARH even in their lastest SAM systems has brought be to this idea in the first place. There are no hardware changes necessary for this operation mode. Even the S-500 seems to have SARH elements and the active seeker for naval S-400 is most likely for over horizon engagement of sea skimmers.
PeeDRussia might do limited tech-transfer on a system like Antey 2500 which is not deemed important and to some extend obsolete. But the S-400 is another story, it has just been cleared for export and is the new backbone of Russian SAM systems. Neither China and probably also not India would get a tech-transfer deal, hence I see no chances for Turkey getting one. Furthermore, stay realistic, the S-400 is a highly sophisticated system, which radar element would Turkey want to replace? The Big Bird radar is called a battle management radar because of its high sophistication based on more than three decades of experience from its first version.
With a system like Antey 2500 this might be possible for a country with no experience or history on long range radars because they could take advantage of new technologies like a AESA aperture, but not with a system that went operational with the worlds best SAM designing country just 10 years ago.
PeeD@SpudmanWP
1. The radar knows where the F-35 is in order to keep it in the illumination beam
2. The SARH missile has the spare energy to virtually pass the F-35, do a U-Turn, and then catch up while not being in the reflection cone.
3. You ignored jamming & decoys from the F-35
4. You ignored the F-35 maneuvering away from the SARH’s killbox before the missile can get a sniff of the returns.
1. This is the basic starting point for the concept, a higher tier sensor must know a coarse location (e.g Container OTH) and a high power low-band system must establish a more accurate track and identification (e.g Resonaz, Nebo-M).
2. A heavy heavy SAM like S-400 comes down from more than 25km altitude flying at a energy optimized lofted trajectory, I would even expect that down to the altitude of the VLO asset it will just consume the potential energy for its positioning maneuver while maintaining ist coasting velocity (incl. adding aerodynamic losses).
3. That goes for a conventional fighter as well and is quite difficult against a sensor fused SAGG guidance.
4. The missile has the absolute kinematic superiority to position itself to any position necessary relative to a F-35, the JSF will never win that game (engagement wont last long enough).
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@garryA
Well , no. Once your missiles is coating, you would have to expect a decrease of 1 Mach or even more for every hard turn. A hard U turn would likely decrease your missiles speed from Mach 4 down to Mach 2 or lower, then any further maneuver from the aircraft will decrease your missiles down to subsonic speed
The position maneuver is not as hard in real scale as you may think. The potential energy in altitude delta should be sufficient to avoid any velocity loss in scale of one mach. Long range heavy SAMs are designed to have excess kinematic reserves. The potential energy is better used for a positioning maneuver than heating it up by friction.
It depend, because lift is also a function of velocity so if you go slower, it is likely that you won’t generate enough lift for the same max G.
Agreed. As I don’t expect post-maneuver velocity deltas in range of one mach number, I don’t expect the aerodynamic control to be unable to pull max G down to mach 2.
If you can get the missiles close enough for its warhead to be effective by third party sensor then there is no point for the SARH to start with. By using SARH , you already exposed yourself to significant threat from anti radar missiles. Moreover, if you can get missiles close enough for its warhead to work then the terminal ARH seeker will work too
I think you really over simplified the scattering pattern of VLO assets that they either face the missiles or the ground radar, while that not really the case in reality
Third party sensors are expected to be too coarse for effective targeting (adverse conditions).
Exposure of the illumination radar to ARM should be too off-topic here, we can talk about that in a other thread if you want.
My scattering pattern is naturally a simplification but for adverse conditions, its unlikely that the deflected waves point that far to the opposite direction of the illumination radar. Its there to show the basic principle.
Even if the method work in some rare occasion, it still doesnot neglect stealth because there are effect of RAM as well.Moreover, the missiles will have much lower PK if it always have to make maneuver just to get in position then chase the target
It potentially neglects stealth for a SARH seeker with SAGG guidance and a advanced networked IADS, I didn’t criticize stealth in other contexts. RAM, well what fraction of total stealth performance is due to RAM?
It may looks very simple to do in your graphic, but that is only because the graph is not to scale and you are drawing in 2D.
Firstly, your missiles has to make very hard turn to get in the reflection lobes (assuming you know where it located), this is a energy consuming maneuver , even worse when it is in terminal phase
My graphic is intended to simplify the situation in order to show that scatter/deflection lobes (likely >50% of illumination RF energy) can only be at a certain torus like position around the aircraft, with the axis of the torus pointed towards the illumination radar, not randomly anywhere. This axis aligned torus would fluctuate in RF energy scattering with changes of the VLO asset direction/aspect. However even if the RF energy scattering in the torus area is down to 10% of total illumination power on the aircraft due to changing aspects, its sufficient for terminal SARH seeker lock-on.
Secondly, you changed missiles intercept profiles from head on to tail chase , thus reduce effective range of missiles more. Even without any turn involved, the tail chase range is already much shorter than head on intercept range
…
Last,you only think about reflection lobes of VLO asset in a 2D images thus create the impression that it will need to turn a significant angle to point the lobe aways from the missiles while in reality a slight roll would do the job
Look at the nose and try to imagine the reflection lobes in 3D form
Not necessarily, could be a steep lateral attack still within the frontal half (my graphic shows adverse condition with a very high deflection performance of the VLO design). I think you know that a gimballed seeker can search for fluctuating scatter spikes without the need to change the course of the missile. This also means that if spike signals are getting weaker, the gimballed seeker can position itself to where the spike is computed to moving to or search for a new spike (all in context of a redundant SAGG system).
Technically you can determine that target is moving by consider it in the range gate, but for that the reflection has to come back to the ground radar, while it not really the case here
…sotiphicated MTI method such as what ?
No. As said, the concept is about a higher tier sensor to have detected the VLO asset in the first place. Hence target vector would be known. This was a out of the head concept for a MTI function for the case, I have no technical radar document at hand now with a MTI function description that would fit for this case, pardon this vector correction method of mine is all I have at the moment.
PeeD@garryA
Very impractical, a U turn like that would deplete your missiles of most speed it has build on the way to target. Especially consider that the terminal phase of most missiles is coasting. Unlike in the movie , BVR rarely make more than 1-2 hard turn at long range. Moreover, high velocity mean very big turn radius as well
Yes its coasting but we are talking here about high mach numbers of 3 and above in terminal phase. Some depletion by some additional maneuver will decrease the speed but not most of the speed. Even if speed is decreased from mach 3 to mach 2, the lower speed also increases the effective turn rate for the same max. G pulled. Again, its a detail that would not decrease the PK significantly to question the concept.
Those are extremely important detail because unlike a ship, an aircraft can change its aspect very quick and are agile enough to evades missiles launched at them. Anti ship missiles can use very complex maneuver to approach target because their target hardly move at all or move at very slow speed. An anti air missiles trying similar approach will likely deplete itself of energy to intercept target ( or PK will be reduce alot)
As said you have to deal with a redundant SAGG guidance here. Should maneuvering really come close to break the lock of the gimballed SARH seeker, command guidance can take over and in worst case use coordinates of the senor asset that has detected the VLO asset in the firt place, to use the large proximity warheads of heavy SAM for a last dich kill effort. However, in bi-static operation we have good chances for the illumination radar to pick up echos, caused by the SARH seeker evading VLO asset.
If you already has the location of target then what the point of using this method ? , why not just use ARH missiles + datalink ? or IIR missiles?
The idea is to make use of existing, mature SARH technology which coincidentally (potentially) has a natural effect of bi-static operation which could be effective against VLO assets. IIR for BVR is not as mature and ARH could be judged to be not robust enough (F-35 RSC now claimed to be that of a pea). The idea of a ARH SAM/AAM attacking a VLO asset from above where the RCS is expected to be significantly higher sounds reasonable, but the idea that you could basically neglect stealth via bi-static operation and see it crystal clear sounds more promising.
I said it is hoping because you literally want the SARH missile to home on the main reflection lobes of a complex moving target. Not only that you have to guest/estimate where the main reflection lobes is , you also have to hope that it either point at the missiles or at your radar. Then your missiles have to perform maneuver that really cost energy. Moreover, target can change direction too, thus making things even more complex. To be honest, i cant see how this is better than just use IIR missiles or active radar missiles
The deflection pattern is strongly dictated by the illumination radars position. It is not as random, even in maneuvering, as you expect. I have prepared a simplified graphic to make it more clear. What you expect to be a lock breaking change of the deflection lobe, are expected to be lobe fluctuations by me, not a cancelled deflection lobe.
Doppler shift doesn’t depend on how modern your system is though.
With digital technology, I could think of a computed correction factor determined by the vectors of radar, seeker, target, not to talk about sophisticated MTI methods.
PeeD@garryA
Well, no. How exactly to you imagined the missiles fly profiles would be ?. Fly directly at target then make an U turn to approach it from the side ?
Basically yes. A command guided flight profile to bring the missile in a position relative to the target where this bi-static operation is possible.
I honestly dont get what are you trying to say ? Both the shape of the car and the position of the tube will dictate the deflection angle of the water, not just the tube position.So if the car turn obviously the defection angle change too
It changes, yes, however these changes would be classified as fluctuations, the general direction band does not change. The position of the tube is a driving parameter, stronger than the change in deflection angles via change of aspect.
If I understood you correctly, you claim that a change of aspect could basically completely change the situation and the seeker lock would be brocken. I think a change in aspect would only de- or increase the deflected RF energy for the positioned seeker, not strong enough to break the lock.
As said, the VLO asset deals here with a redundant guidance principle; if it changes aspect to avoid the SARH bi-static operation, it turns away its optimized face from the illumination radar. This in turn gives the illumination radar a chance to pick up the VLO asset on its own and a SAGG guidance is so dangerous because it weights the situation and can instantly switch between command guidance and SARH guidance.
Normal BVR always climb at initial phase and dive down at terminal phase.So this have been taken in to account of stealth aircraft designer. But if you want your proporsal to work, your missiles need to dive down target but from side aspect , not from front. And the major problem is that if target change direction then the location of their spike will change also
The missile of the system I described would fly a lofted energy optimized trajectory for ~80% of the range and then go for a positioning maneuver and then terminal SAGG guidance. There could be cases that due to angle of attack of the illumination radar and the stealth design, the biggest portion of the RF energy would be deflected to and downward direction. Hence for such a bi-static operation, it could be necessary to attack from e.g 45° off the boresight of the VLO asset in vertical and horizontal planes. But well, these are just details.
Your explaination isn’t sufficient
You cant just blindly illuminate a space then launch missiles randomly at the blind space and hope that the there would be some reflection from something there and the missiles can home on the reflection to target.
There are plenty of problems:
1/ Rule of engagements
2/ Chaff , decoy
3/ Do you launch enough missiles to cover every possible aspect that target can have high RCS spike ?
4/ When to launch the missiles if you are not intended to measure range?
This blind operation is the key for this concept to work. You know your own coordinates, you know the target coordinates (via other sensor assets), you know the mainlobe illumination area at given target distance and you know that you have robust communication links to all involved assets.
Its not about hoping, you know that there certainly is a VLO asset at the provided coordinates and you know that the redundancy of your guidance system will either result into a detection and view of target via the bi-static positioned SARH seeker or force the target to change aspect and expose itself to your illumination radar during terminal phase. You are also sure that the SAGG system will instantly chose between the redundant inputs, optimally.
The illumination radar of the S-400 is sophisticated, with large computing resources, I don’t think it would fall for chaff.
The concept is also not about covering every possible aspect, the direction band where RF energy is deflected is limited. A 45° position above/below and 45° to the side of the target is a good candidate together with the gimballed SARH seeker.
As for range: You always have the coarse target coordinated via the other sensor assets, otherwise the concept does not work. Other sensor assets would provide a sufficiently accurate target position/range for mid course guidance up until terminal phase.
The problem is you assumed that once aircraft turn aspect with low RCS toward the missiles, it will present the fire control radar with a high RCS spike. But that is not neccessary true.
With the SARH seeker at the right position, I think there is a direct correlation.
The reason radar can distingush between chaff and target is due to Doppler shift. Doppler shift is created due to the radical velocity of target and the transmitter.
A SAGG system with networked multi-band and high resolution sensors, could very be well able to distinguish between chaff and VLO asset. Whether a state of the art FMCW illumination radar would not be able to provide a modern seeker with a useful doppler shift via side reflections is questionable.
PeeD@garryA
If missiles are launched at aircraft then it is expected that pilots will try to dodge them. They will not maintain a constant course
Yes it will maneuver at the last phase agreed. But the concept does not change, there will only be more RCS fluctuations. As said a good stealth design deflects radar waves from a threat radars boresight. A ideal all aspect design would do this at every aspect with the same performance. Let me make a simple example: A car on a turntable is sprayed by a high pressure firefighting tube –> the deflected water around it will fluctuate at different aspects but the position of the tube dictates most of the deflection behavior/direction.
2/ The high RCS spike is very small and often concentrated to the side so your missiles will have to approach target from very awkward angle, which isn’t good for kinematic either
A typical energy optimized trajectory via autopilot updated missile up-link with a dive down maneuver at terminal phase (at long ranges) or a climb from below (short ranges) would likely do it. Energy cant be eliminated; the deflected RF energy (minus the RAM/RAS absorbed portion) will be a strong signal, in quantity about the same amount of RF energy reflected by a conventional design.
3/ When do you know when to launch your missiles if the signal is too weak for your fire control radar to detect target in the first place ?. If the signal is strong enough for radar to detect then why need bi static ?
I explained this in the first post of this thread. The basic idea is to use other sensor assets input into the IADS/GCI to enable a x-band attack system to do something it would be otherwise unable to do via this proposed bi-static effect.
The deflection angle is not confined because it will change depending on what direction the aircraft pointing at
Above I explained the behavior of a ideal all-aspect stealth design, it always deflects the waves away from the boresight of the attack radar. This will probably never be realized. The weaker the design gets at different sections, less waves are deflected and can travel back into the direction of the emitter, causing fluctuations at the SARH seeker. However a SAGG guided missile will also benefit from aspects where less RF energy is deflected because the ground based fire control radar will start to receive echos and use command guidance if seeker lock has been brocken.
Lets put it simple, a good stealth design deflects more RF energy into direction where a potential bi-static SARH seeker/receiver can be positioned.
A bad stealth design deflects less into presumably safe directions and sends back echos to the attacking radar boresight.
A SAGG guided missiles makes use of both of this worst and best case scenarios and the fluctuations between them.
The only effect of Bi static configuration is that your receiver can be put at location/ aspect where there is strongger reflection. However, the problem with Doppler and the need for range measurement is still there. They don’t just disappear.
Without Doppler processing , missiles will missiles everytime VLO aircraft release chaff. Without range measure your missiles will suffer in kinematics because it cant take advantage of lead intercept
The kinematic penalty would be negligible because its limited to terminal phase. CW designs such as the HAWK/SA-6 seekers have no doppler range measurements. Even if your argument is right and a modern FMCW illumination radar would have problems to create the necessary doppler shift of such deflected waves: A SAGG based system will have analytic means to distinguish between chaff and target.
PeeD@garryA
I think a change of aspect or direction of the VLO asset would not change to overall situation. First there is the question whether it would be worth the risk to change direction after the attack has been detected by sensors and the most optimized face (front) has been directed to the threat emitter.
Even a all aspect VLO asset would still be optimized to deflect waves away from the bore sight of the threat radar. If we assume that the biggest portion of the radar waves are deflected in a bore sight range of 15° to 90° in all directions, a limited degree portion can be determined from the bore sight of the threat radar where the SARH seeker has to search for deflected RF energy. However I’m no expect on RF wave behavior hence this deflection angle band could differ.
More so; if the VLO asset changes aspect relative to the bore sight of the threat illumination radar to change the direction of deflected radar waves, to decrease chances for the bi-static SARH seeker to pick up RF energy, this would force it to expose a less optimized face to the bore sight of the threat radar. So if the SARH seekers lock on the target is broken, the redundant SAGG/TVM system could switch back to command guidance mode as it now has got a own track of the VLO asset.
You may be thinking about a sudden maneuver that would suddenly break the lock of the SARH seeker. But any change would just reduce the amount of deflected RF energy e.g if the VLO asset exposes its least optimized face to the threat emitter, so that more RF energy is sent back to the radar and hence less is deflected to the bis-static positioned SARH seeker.
Advanced SARH missiles with missile up- and down-links + advanced autopilots only make use of the SARH seeker in terminal phase, not like the HAWK or S-200 which had to catch the RF energy at great distances while on the launcher. Hence they need much less of reflected or deflected RF energy. The deflection angles of VLO assets are confined and there should be enough RF energy deflected to that angle band to allow for terminal phase SARH guidance.
As for cutter levels. I’m not sure if doppler shift is a necessary effect in such a bi-static operation mode. The seeker just tries to get more RF energy, i.e it steers to the position/direction that offers this together with all the SAGG inputs. Range calculations are not essential and if, the performance of digital MTI (in SAGG guided missiles inside the ground based engagement radar) has greatly improved in the recent years, this should not be a dealbreaker.
PeeD@Marcellogo
I think its possible that SARH SAMs and AAM with missile up-link course updates until terminal phase are more effective against stealth/VLO targets than the same for ARH seekers. As said, they work effectively as a bi-static radar. Given that the main technique of stealth/VLO designs is a geometry that avoids radar waves to directly bounce back to the radar receiver which sent them, –> the waves must be deflected into a other direction. This other direction where the RF energy is deflected to, can be exploited by a bi-static radar, which a SARH/SAGG/TVM guided SAM/AAM effectively is. Its auto-pilot/INS can position it via course updates at a position or angle where the radar waves are most likely deflected to, do a sniff maneuver in terminal phase, catch the RF source and home on it.
This bi-static feature is only present in SARH missiles, a ARH seeker must rely to be guided close enough to the target to receive a echo. Hence I think this property of SARH missiles have kept them alive for operators which have to face stealth opponents and not only the reduced cost/technology. To really exploit this possible effect against stealth targets, an advanced system and IADS such as the S-400 is necessary.
PeeDSome elements of the S-500 apparently also use SARH/SAGG SAMs. The lower tier and cheaper than S-400/S-500, S-350 with its 9M96 uses ARH yes. As there are physical limits to effective illumination range it would also be a Explanation why the long range 380km SAM of the S-400 and likely long range components of the S-500 would use ARH (because there is no SARH alternative)
PeeDThats a subcale combat variant of the RQ-170 if you will, called Saeghe and building on RQ-170 tech but not a copy. A flying wing not only has benefits for stealth but also benefits for range and payload.
The 1:1 scale copy of the Sentinel is visible in the background right side.
PeeD@SpudmanWP
Interesting paper. The design is for a very large fighter-bomber and the lowest band tested in the simulation was one GHz, with 0.3m wavelength.
Modern VHF band radars however work at down to 100-150mhz, which is 2-3m, a difference in wavelength of the factor 10.
There will be a disproportional increase in detection range against a similar aircraft.
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