054/A FFG Thread II

[Tam]

TVM is a form of command guidance all the way to target. It is not "essentially SARH" because the missiles do not carry the computers required to fully process the received radar signals and continually compute an interception path. It is more accurate to describe it as having some features of SARH, while being essentially command guidance.

In TVM, the ground radar must track the missile. This is not necessary in SARH.

In TVM, the missile receives the echoes from the target. So it is essentially bistatic radar like SARH. The back end is not the issue here but how it measures.

PD works on a monostatic application. It determines range by obtaining the time of the echo, using the speed of light as a reference and divides it with a constant of two. Why 2? Because the transmit and reflect distance is the same, with both receiver and transmitter at the same place. With PD, the pulse cycle is set long enough so that there is enough time to receive the echo, so the farther the target, the longer the pulse cycle. the nearer the target, the shorter the pulse cycles. This does not work well for SARH or TVM which are bistatic because the pulse cycles are constantly changing as the target changes distance with the PD radar. Remember that TVM stands for Track Via Missile. It has a receiver on the missile.

In a bistatic application, with the receiver and the transmitter station not being the same, the distances between the transmitter and the receivers to the target are different from each other and it can be assumed that both are now unknown. It is impossible to determine the distance of the missile from the target based on the reflection from the PD radar because missile distance to the target which is the receiver and station distance to the target which is transmitter, are not the same.

So the missile takes the reflected waveforms from the target, and compares that to a reference waveform, which it receives from the station. By making this comparison, you get the difference that the doppler effect generates, and that's the important data you need as this will measure the rate of closure of the missile towards the target. SARH will automatically processes the information through its onboard computer, TVM will transmit that information back to the target and uses the much more sophisticated computer the ground station has to determine the interception trajectory.

The fact that you're bistatic with separate transmitter and receivers makes it ideal for CW use, and CW doppler is best for speed and rate of closure measurement that are essential for missile accuracy. Active guided missiles could be PD because of their single antenna, and because as they get close to the target, remember this is a monostatic application, the pulse cycle changes to a high and higher PRF, and very high PRF has characteristics similar to CW as it can appear continuous.

 

[Tam]

It becomes a religious argument that won't lead to anywhere. Let's agree to disagree.

Spoiler: imaging infrared and no radar

Spoiler: with a speed of an interwar biplane actually

Your argument is self-defeating.
As per your own argument, lesser need to rely on datalinks is the advantage of supersonics. And, vise versa, if updates are not a problem(your navy maintains a necessary degree of sea/airspace control) - it goes away. Simple as that.
And this is precisely why supersonics appear so much on applications where updates aren't assured. This was one of the reasons for their birth, to begin with.

Missile shows its front to the enemy, not sides, and wings have some wing sweep angle. Point taken, though - there are indeed better missiles from the all-aspect RCS PoW.
Plume from a small transonic missile may easily be hidden. Strictly speaking - it's one of big advantages of supercruise even for 5th gen fighters - heat signature goes down dramatically. And here we're talking about very small engine right next to the water.


1st is true. 2nd - we don't know.
I'd personally suggest they can't just switch from YJ-83 to YJ-12 overnight.

Somehow saying that you cannot make a supersonic missile stealthy is like saying a supersonic jet cannot be stealthy.

OOPS.

Being stealthy is a separate factor from the speed. You can make a stealthy supersonic missile. The point is, even if you are not trying to be stealthy, a supersonic missile can be stealthier than a "classic" subsonic antiship missiles, like Harpoon, Exocet, YJ-83, TASM, YJ-62, Uran, RBS-15 and so on. Trying to show a deliberately designed for stealth ASM as some kind of argument that a supersonic cannot be stealthy is one that has no connection to it.

Having to superiority of the airspace has little to do either with the "stealthy" argument. Having plenty of traffic is non stealthy to begin. ESM can pick up the datalink. Furthermore, if the target has moved away from the point it has targeted with because it takes say, 40 minutes to get there instead of 9 minutes, the missile actually has to fly high, reach a height for loiter and uses its seeker to scan looking for the target. That makes it conspicuous and its radar seeker picked up by ESM.

The less time the missile is in the air, the less it requires to use data link, the less that it needs to loiter and search for targets, the greater its element of surprise.

Unlike the Russians, the Chinese do not think they will lose the minimum state of air and sea control, which is why their ASM inventory is mainly subsonic. Their institutional bias is towards the subsonic missile, so for them to accept supersonic missiles (note that Japan too has a similar situation) is a decision that did not come hastily. You can bet they did plenty of homework and simulation studies for this before arriving to that conclusion.

With regards to plume, as far as the plume argument goes, it still goes backward even for a supersonic missile.

Missile shows its frontal aspect to the enemy. Hence its sharper nose and more angled wings, with sharply pointed intakes have a lower RCS than a subsonic missile with a blunt radome. This is even without trying to deliberately include stealthy features. This comes inherently from its aerodynamic design. And because exhaust plumes head backward, not forward, its also a non argument.

Another reason why plume argument is useless is because IR seekers are designed to capture such levels of temperature nuances as the friction of the air against the surface of the missile. That's where the missile is more easy to pick up. But that is also true of subsonics to a lesser degree but not to a degree that it is impervious to the modern IR sensor. Remember that IR missile seekers achieve frontal aspect long ago, when the first AIM-9s and the Python were able to do that, and for the Chinese, their first PL-8s. You are going to counter this by running liquid cooling underneath the skin, but an aircraft has the space for that, difficult on the tight space for a missile.

Then you have to think steps ahead. How good is your stealthy subsonic antiship missile against next generation AESA radars with Gallium Nitride? Like you know, SPY-6 and all that? My opinion on this is that stealth advantages will erode further and further as time goes on, and that technology will be on the radar's side. Eventually that will leave you with brute speed. Hence the scramble for hypersonics.

 

[Tam]

CG artist turns steamer and 'tuber explains the differences and nuances between the different Type 054A batches in this video.

 

[nlalyst]

In a bistatic application, with the receiver and the transmitter station not being the same, the distances between the transmitter and the receivers to the target are different from each other and it can be assumed that both are now unknown. It is impossible to determine the distance of the missile from the target based on the reflection from the PD radar because missile distance to the target which is the receiver and station distance to the target which is transmitter, are not the same.

You are trying too hard to look at TVM as a form of SARH, whereas it is really a type of command guidance. The distances of the target and missile are known to the ground radar, because it tracks them both. The same for their speed. At minimum, the reflection picked up by the missile seeker is used to refine the angular resolution of the target. I can easily thinks of ways the missile could get range and speed data, but that may not even be necessary as both are known to the ground radar.

Active guided missiles could be PD because of their single antenna, and because as they get close to the target, remember this is a monostatic application, the pulse cycle changes to a high and higher PRF, and very high PRF has characteristics similar to CW as it can appear continuous.

Isn't that essentially how ICWI works? Even some old radars like the AWG-9 could provide PD illumination for SARH missiles like the Sparrow or even guide the Phoenix in SARH. I think they called that the PD STT (pulse doppler single target track) mode. Actually, the AIM-7F was the last Sparrow to support both CW and PD homing. All subsequent variants supported PD mode only (ICWI). So you see, PD "illumination" is possible in multi-static configuration.

A bit more info, from the Radar Handbook by Skolnik, on how PD illumination SARH works, and why it is desirable. Also, how it compares to ARH.

The motivation for the use of PD in the seeker was to simplify the illuminator in air-to-air systems. For early-generation airborne radars, which employed a noncoherent pulse waveform, CW injection was the only practical solution. With the advent of coherent PD radars, an alternative way to achieve virtually CW operation without the penalty of the additional transmitter became available. This was to select a high-PRF (pulse repetition frequency), high-duty-cycle (30 to 50 percent) waveform and to use only the central line of the PD spectrum, both in the radar and in the seeker. This has sometimes been called interrupted CW (ICW).

A high PRF is defined as one which is unambiguous in doppler. Thus when the receiver selects the central line, the spectrum is identical to the CW case. The radar receiver must be protected during transmission (duplexing and/or gating).
In addition, the receiver may or may not use a range gate. If only the central-line power of the PD spectrum is used (no range gate), the resulting loss must be accepted. Use of a range gate matched to the pulse avoids this loss. In either case, the rest of the receiver and signal processing is the same as for a CW system

The seeker implementation follows this same pattern. However, range gating in the seeker is generally not used with a high-duty-cycle system. The loss resulting from use of only the central line is essentially the duty cycle dt. For a peak transmitted power the average power in the central line is Pt(dt)2, compared with the average power of the transmitted waveform of Pt(dt).A low duty cycle (less than 10 percent) can also be used, but for this case thecentral-line power loss becomes prohibitive. Low-duty-cycle systems, therefore,must use range gating to optimize performance. In addition to retaining dopplerresolution capability the range-gated system provides range resolution.

Active Seekers.
Active seekers can provide increased firepower as wellas fire-and-forget (or launch-and-leave) operation. Thus, they have found application in both the air defense and the surface-target attack roles.An active seeker is functionally the same as a semiactive seeker, with the ex-ception that it carries along its own illuminator. Besides adding thetransmitter, the other main difference in the active seeker configuration is elimination of the rear receiver, with the reference generated by offsetting the transmitter excitation (or drive) signal, as shown in Fig. 19.9. Active seekers, since they use a single antenna both to transmit and to receive, cannot use CW because of the very limited isolation achievable. Noncoherent pulse or coherent PD waveforms have been employed, and either the central-line processing or the range-gated approach can be used for coherent operation.

 

[Gloire_bb]

Somehow saying that you cannot make a supersonic missile stealthy is like saying a supersonic jet cannot be stealthy.

OOPS.

Well, there is quite a lot of contradiction between stealth and performance, no argument here.
For supersonic missiles, compromises are simply that much larger, and achieving operationally measurable stealth performance is that much harder. On a single-use airframe, where overly expensive solutions are tricky - this is multiplied yet again.
Point is, reducing signatures(all of them) for a subsonic sea skimmer is not just doable, it plays into their strengths, comes cheap, and is absorbed pretty well by the efficiency of their air-breathing engines and lift.

The point is, even if you are not trying to be stealthy, a supersonic missile can be stealthier than a "classic" subsonic antiship missiles, like Harpoon, Exocet, YJ-83, TASM, YJ-62, Uran, RBS-15 and so on.

Examples?

Having to superiority of the airspace has little to do either with the "stealthy" argument. Having plenty of traffic is non stealthy to begin. ESM can pick up the datalink. Furthermore, if the target has moved away from the point it has targeted with because it takes say, 40 minutes to get there instead of 9 minutes, the missile actually has to fly high, reach a height for loiter and uses its seeker to scan looking for the target. That makes it conspicuous and its radar seeker picked up by ESM.

Datalinks can be picked up in principle, no doubt here, but they may be directional(as well as simply hidden behind ECM). Having your assets in the air allows these updates to be pretty hard to intercept.
Higher flying search is indeed unstealthy - and this is where modern(2010s) search algorithms and flight tame play in hand. A LRASM-like missile can simply search down low (which it is actually designed to do) - this is, assuming that there is something wrong with midcourse updates.

Unlike the Russians, the Chinese do not think they will lose the minimum state of air and sea control, which is why their ASM inventory is mainly subsonic. Their institutional bias is towards the subsonic missile, so for them to accept supersonic missiles (note that Japan too has a similar situation) is a decision that did not come hastily. You can bet they did plenty of homework and simulation studies for this before arriving to that conclusion.

More like their navy is designed to perform as such - which is reasonable for their . Note, that regardless of that, parts of PLAN, PLANAF strike arm, and JASDF are specifically designed to perform no matter the situation. And, due to a change in situation - ROCAF now transforms into much more of a sea denial force, as opposed to sea control. Curious lil navy.

With regards to plume, as far as the plume argument goes, it still goes backward even for a supersonic missile.

Missile shows its frontal aspect to the enemy. Hence its sharper nose and more angled wings, with sharply pointed intakes have a lower RCS than a subsonic missile with a blunt radome. This is even without trying to deliberately include stealthy features. This comes inherently from its aerodynamic design. And because exhaust plumes head backward, not forward, its also a non argument.

Examples?

Another reason why plume argument is useless is because IR seekers are designed to capture such levels of temperature nuances as the friction of the air against the surface of the missile.

Before that happened, early front aspect locks by heatseekers were made against supersonic targets: their plume "nimbus" is a good, hot target, which can really be only hidden by airframe(doesn't work well with supersonic missiles - too much to hide). Furthermore, cooling surfaces at supersonic flight at ranges important for ASCMs is very difficult, and I don't remember any examples.
Finally - all the same is true to a significant degree in radar spectrum as well - shock cones and plume reflect quite a lot. Even frontally.

Then you have to think steps ahead. How good is your stealthy subsonic antiship missile against next generation AESA radars with Gallium Nitride? Like you know, SPY-6 and all that? My opinion on this is that stealth advantages will erode further and further as time goes on, and that technology will be on the radar's side. Eventually that will leave you with brute speed. Hence the scramble for hypersonics.

Sort of. But for the 2020s, wast majority of ASCMs are subsonic - either fully or mostly(YJ-18). Only 3 navies in the world consciously embrace supersonic missiles as their primary ship-to-ship strike weapon - Russian, Indian, and now ROC navies. There is also a mixed case of Indonesia - and this is it.
---
When we're talking about a weapon for a general purpose frigate of a navy aimed at equal fights (navy as a whole) - I, frankly, view the new YJ-83 as a "good enough" solution. Especially when many of its targets are actually quite small and nimble.
As for how PLAN views it - we'll see in a few years, I guess.

 

[AndrewS]

@Gloire_bb

On the utility of subsonic missiles.

Let's say a SAM system has a probability of kill (pk) = 0.7
A subsonic missile will face at least 4 engagement rounds after crossing the horizon.
There's virtually a 100% chance that all the incoming subsonic missiles will be destroyed.

Existing air and missile defense systems are “very effective “are very effective against a threat moving slowly enough to give us time to acquire track, target, and deploy a shooter,” he said, but hypersonics just move too fast for current defenses to intercept.

The Pentagon’s chief of R&D, Mike Griffin

breakingdefense.com/2019/03/lasers-hypersonics-ai-mike-griffins-killer-combo/

 

[nlalyst]

@Gloire_bb

On the utility of subsonic missiles.

Let's say a SAM system has a probability of kill (pk) = 0.7
A subsonic missile will face at least 4 engagement rounds after crossing the horizon.
There's virtually a 100% chance that all the incoming subsonic missiles will be destroyed.




breakingdefense.com/2019/03/lasers-hypersonics-ai-mike-griffins-killer-combo/

What do the numbers say when you factor in that subsonic missiles (NSM) can be up to 10 times lighter than supersonic missiles (Moskit) for roughly the same range?

A YJ-12 weighs 3 times as much as a LRASM, but has less than half its range. A single B-1 can carry 36 of those bad boys and lob from 1000km away. With a max 400 km range, a bomber loaded with YJ-12s would be well within CAP range and would require substantial air superiority fighter escorts to break through within firing range. Whereas, one loaded with LRASMs might be able to just avoid them all together and saturate the target with 3 times as many missiles.

 

[Maikeru]

What do the numbers say when you factor in that subsonic missiles (NSM) can be up to 10 times lighter than supersonic missiles (Moskit) for roughly the same range?

A YJ-12 weighs 3 times as much as a LRASM, but has less than half its range. A single B-1 can carry 36 of those bad boys and lob from 1000km away. With a max 400 km range, a bomber loaded with YJ-12s would be well within CAP range and would require substantial air superiority fighter escorts to get within firing range. Whereas one loaded with LRASMs might be able to just avoid them all together, while saturating the target with as 3 times as many missiles.

Indeed, and subsonic AShMs still require the target or its escorts to expend their limited number of missiles and munitions on defeating them, leaving less available to deal with any follow-up strike.

 

[blindsight]

What do the numbers say when you factor in that subsonic missiles (NSM) can be up to 10 times lighter than supersonic missiles (Moskit) for roughly the same range?

A YJ-12 weighs 3 times as much as a LRASM, but has less than half its range. A single B-1 can carry 36 of those bad boys and lob from 1000km away. With a max 400 km range, a bomber loaded with YJ-12s would be well within CAP range and would require substantial air superiority fighter escorts to break through within firing range. Whereas, one loaded with LRASMs might be able to just avoid them all together and saturate the target with 3 times as many missiles.

Nobody really knows these missiles' real specs. According to 兵器知识，The land-based version of the YJ-12 could go up to 1000km. I think the real limitations would be tactical.

 

[AndrewS]

What do the numbers say when you factor in that subsonic missiles (NSM) can be up to 10 times lighter than supersonic missiles (Moskit) for roughly the same range?

A YJ-12 weighs 3 times as much as a LRASM, but has less than half its range. A single B-1 can carry 36 of those bad boys and lob from 1000km away. With a max 400 km range, a bomber loaded with YJ-12s would be well within CAP range and would require substantial air superiority fighter escorts to break through within firing range. Whereas, one loaded with LRASMs might be able to just avoid them all together and saturate the target with 3 times as many missiles.

Yes, a B-1 can carry 36 LRASMs worth more than $100M.
But they are likely to be all shot down by the defending SAM system.
That is what the DoD official already said (as per Undersecretary Griffin)

Plus you have the wrong missile comparison for China.

For the same weight as 36 LRASMs, the comparison is not YJ-12s.
Instead, you could have 2x air-launched DF-21 IRBMs. Call it $40M for those 2 missiles.
Plus it has a far greater range of 2000-3000km and travels much faster, up to Mach 10

Remember that even the future US Frigate is going to cost over $1000M.
Destroyers and other ships are even more expensive.

So it's worth launching lots of longer-ranged DF-21 missiles.

This logic is why the US military has gone on a hypersonic weapons development binge
They know (as per Griffin) that hypersonic missiles trump LRASMs