Sunday, February 24, 2019

Scout Ship

We recently discussed the Navy’s ill-conceived plan to use unmanned vessels as sensor scouts out in front of a surface group (see, “Navy’s Manned-Unmanned Fleet Concept”).  We noted problems such as small size, limited endurance, questionable speed, high cost for an expendable vessel, broadcasting their own location (due to active sensors), and lack of defense.  The alternate option is to use small UAVs which would accomplish all the same goals at a fraction of the cost.

The Navy is correct in their desire for long range sensing – just wrong about how to accomplish it.  As we begin to procure some longer range missiles (LRASM, NSM, anti-ship Tomahawk), longer range targeting becomes critical.  As I’ve said many times, it’s pointless to have a ten thousand mile missile when your sensor is only good to the horizon.  So, good for the Navy for recognizing the need but they missed the mark on how to do it.

In addition to UAVs, there is another option for long range sensing that is actually closely related to the Navy’s unmanned sensor vessel yet solves most of the small sensor vessel’s drawbacks.  The option is a  larger, manned, scout ship sensor vessel but with a different concept of operations (CONOPS).  Let’s take a closer look.

The biggest problem (that’s actually debatable because the vessel has a lot of problems and they’re all pretty major!) with the Navy’s planned 130 ft long sensor vessel is that it will have to use active radar to find anything and get a targeting location.  Think about it … a tiny vessel will have a very low radar mounting.  A vessel that size will have its radar mounted perhaps 20-30 ft above the surface.  That makes for a very short radar horizon – something on the order of 12 nm or so (there are radar horizon calculators readily available on the Internet if you care to play with the numbers).  Using active radar will give away the sensor vessel’s location long before it can find a target.  Plus, with a sensor field of view that small, the vessels will be nearly useless for providing area coverage unless there are a LOT of them and large numbers simply compound the problems we’ve already identified.

The alternative is to use passive sensors.  The problem with this approach is that passive sensors generally provide a bearing but not range.  Of course, the passive sensor can, over time, develop a range by moving and triangulating – this is what a submarine does.  Alternatively, two or more sensors operating at different locations can work together to fairly quickly establish the target’s position.  The problems with small vessels remain, however.  They are poor sea keepers, have limited endurance, and are too expensive to be the expendable asset they would need to be when used the way the Navy intends.

Alternatively, let’s consider a significantly larger, corvette-size vessel that operates not in front of a surface group but around the periphery, offset well to the sides, and uses only passive sensors.  Due to the nature of the various signals of interest and the effects of atmospheric phenomenon (ducting and the like), passive signal detection can occur far beyond the horizon.  Thus, passive detection range is much greater than active sensors.  The trade off, as we noted, is that passive detection provides only a bearing, not range.  This is where using two or three vessels comes in – they can combine their data and triangulate.  The vessels would be offset hundreds of miles to the sides of the area of interest rather than grouped directly in front of the surface group.  Given the much greater range of detection and area of coverage, only a few vessels are required rather than the Navy’s vision of mini-fleets of sensor vessels.

Wait … communicate and triangulate?  How can they communicate?  Haven’t I repeatedly stated that we won’t be able to maintain a viable network of data in peer war, electromagnetically challenged environment?  Yes, I have.  The difference is that this approach does not require constant communication because there is no need for real time data fusion – thus, no network.  Occasional bursts of minimal data are sufficient.  If a burst doesn’t get through, you try again – no harm done.  Further, this requires only minimal data:  conceptually, the sensor ship’s location and the threat bearing it detected.  The smaller and shorter a signal transmission is, the easier it is to get through any interference.  The point of these vessels is not to establish real time targeting data with constant transmissions but to develop situational awareness of a broad area – though we’ll gladly take a targeting quality datum if we can get it.  With broad situational awareness, we can then allocate additional sensors (the UAVs we mentioned earlier or an F-35 or whatever) to the known threat locations and establish the final targeting data – or, we can avoid the area if we want to stay hidden.

Visby Scout Ship

We see, then, that with this approach we can establish broad area situational awareness with just a few vessels that won’t give themselves away and won’t have a negative impact on the surface group’s movement, speed, or endurance and, being far away from the likely area of action, the vessels won’t be at exceptionally high risk and will be capable of limited self-defense, if needed.

What kind of ship fits this requirement?  The Visby would be a good starting point (see, “Ship Stealth and Visby”).  It is corvette size but with adequate sea keeping and the potential for good endurance and range.  It is very stealthy and has the basis for SeaRAM/CIWS self-defense.  Most importantly, it has the size to accommodate all the signals analysis sensors, computers, and analysts that are needed.  In short, it would be a very capable, very survivable vessel for the role.

USS Palm Beach (AGER-3) - Electronics and Signal Intelligence Ship
Repackage in a Visby-Type Hull

A Visby-type scout ship could also be equipped with acoustic sensors (towed array optimized for long distance, passive, convergence zone detection) which would further enhance the usefulness of the vessel.

The ES-3A Shadow (S-3 Viking variant) once performed this signals intercept and analysis role for carrier groups but that incredibly powerful and valuable aircraft was retired without replacement.  In addition, it could only operate from carriers whereas this scout ship can operate anywhere.

This CONOPS offers the advantage of providing detection without the enemy realizing they’ve been detected.  The Navy’s proposed small sensor vessels, using active radar, would be easily tracked and offer no advantage of surprise.


Note that this is not a case of mutually exclusive, one-or-the-other options.  I’m not looking to replace every sensor platform the Navy has with just this one scout ship.  This is just another option that better accomplishes the Navy’s intent and complements the other sensor options.  What I’m saying is that I don’t want to hear any comments debating one-over-the-other scenarios because that’s not what’s being proposed.


  1. While extending sensor range is obviously a hot priority, and I agree a more substantial ship is better than the unmanned ideas based on the reasons cited, but I dont see the profit. Arent we only going to gain the distance that the corvette is out in FRONT of the battle group?? Certainly theyre a good fit for defensive pickets to the sides and rear. Or are you proposing them mainly for triangulation assistance with the shooters?

    1. Passive detection range is far, far greater than active. Depending on specific signals and conditions, passive provides detection over hundreds of miles so we gain awareness extending far beyond the scout ship's location.

      I stated that the scout ship's detection mode is passive only and that it would involve cooperative triangulation.

      If you're still confused, reread the post carefully and contemplate the CONOPS.

      You might also want to research what little information there is on OUTBOARD/COBLU. The capabilities of that system is phenomenal from what I've been able to gather and this scout ship would be that system on steroids.

  2. I think maybe im overestimating our current passive capabilities(??) I assumed that the sensors for your proposed corvette would be duplicating systems on Burkes. I saw an article mentioning Outboard/Coblu as being for DDG-51 use...But is it?? What passive EM abilities do we currently have at sea??

    1. I'm envisioning a ship with the combined capabilities of OUTBOARD/COBLUE, ES-3A Shadow, Pueblo, RC-135, and others - well beyond the Burkes. Signals can be collected from hundreds of miles away, depending on type and conditions.

      There is very little concrete information on OUTBOARD/COBLU. I've managed to piece together information which leads me to believe it has some amazing capabilities. You might be better off looking into the ES-3A Shadow.

      Signals collection and analysis is one of the better kept secrets in the military. There is little specific information in the public domain. The Burkes presumably have fairly extensive capabilities given the OUTBOARD/COBLU fit. What they have beyond that, I don't know.

  3. "ES-3A Shadow"

    Of course in the interim there would seem to reason the ES-3A could not be revived out the stockpile of stored S-3s with upgraded equipment and pods and what not. But than again revving all the S-3 would provide some nice strike range for Pacific CVs. But Is suppose current ability is the enemy of future toys that just have to be better (just watch the Lockheed video).

  4. Within your CONOPS could this vessel be combined with the small ASW vessel you propose? One class of ship working as an outer ASW screen and sensor platform. No frills, just the relevant sensors and self defence weapons?

    1. I really like that you're thinking operationally! In this case, though, I'm not sure that pairing would work. The idea of the scout ship is to loiter on the far periphery and remain undetected. A bunch of ASW corvettes dashing about and making noise would just call attention. Remember, the scout ship's sonar array is intended for long distance, convergence zone detection, not close in work.

      ASW corvettes are better suited to convoy escort, harbor patrol, chokepoint monitoring, and the like.

      If you think you see a CONOPS that would combine the two, feel free to describe it.

      Keep thinking operations!

  5. Rheostats may help some of your sensor range/radar horizon issues; Run your sensor up on a tethered balloon. More persistence and (in the case of passive sensors) stealth than a UAV or aircraft.

    1. I'm guessing you mean aerostat? We've discussed balloon sensors before. The problem is that the balloon, itself, is likely to give away the ship's position. "Hey, why is there a large balloon floating in the sky? There must be a ship underneath it." The CONOPS for this idea emphasizes maximum stealth. I'm not sure how much passive sensors gain from additional elevation. Active sensors certainly do but I don't know about passive signals sensors.

    2. @CNOps depending on the type of passive sensor and the type of signal you're trying to detect, passive sensors can face all the same elevation problems that active ones do. For ELINT some signals can bounce off the ionosphere or take other non-direct paths from the source to the sensor, reducing or eliminating the horizon problem, but most of the EM spectrum is only detectable if you're within the emitter's horizon. The horizon problem can actually be even worse for passive sensors than for active sensors because the former can detect emissions from the latter at extreme ranges, meaning they're more often limited by line of sight than sensitivity or noise, while active sensors are often limited by all of the above depending on the circumstance.

      Of course, that's not an argument for an aerostat to serve as a major sensor node in a CVBG or SAG. That said, I'm left wondering if a dedicated scout corvette is superior to a different CONOPs employing either a dedicated ISR aircraft carrier (based on an amphib hull, an escort carrier hull, or the like) or a combination of CGs and DDGs.

      Our current Ticos and Burkes are probably too important and expensive to use in this role, but if you think there's merit in having a dedicated scout surface vessel, I think it's really worth investing in a DD or CC (note: not a DDG/CG) hull so you can cram the really heavy (and important) SIGINT systems in. If you're not trying to keep it expendable then the additional sensors, elevation, and point defenses are all worthwhile.

      "The point of these vessels is... to develop situational awareness of a broad area... we can then allocate additional sensors [UAVs or an F-35 or whatever] to the known threat locations and establish the final targeting data."

      In a highly contested EM environment, I think even this is a lot to ask from a small vessel. Even if the scout ship is undetected, the enemy is likely to be broadcasting a lot of noise during a conflict. To create a decent picture of the battle space requires you to make sensor data, receive it from your peers, deconstruct the signals and noise in each datum (using a lot of computing power), and put it back together without the noise. It takes large, sensitive radar arrays with equally large and sensitive signal processing equipment to tell the difference between (for example) a destroyer's radar emissions and the dozens of similar signals coming from EA aircraft and other decoys. Maybe a corvette hull can fit all that, but I have my doubts.

    3. "The kind of passive signals monitoring equipment we're talking about is cheap and small relative to Aegis/AMDR arrays. Remember, we fit much of this type of gear aboard a tiny airplane (ES-3A Shadow). "

      I did not see this before posting the last comment. I was aware that ISR aircraft exist, and that their payload is universally smaller than that of a corvette, but I didn't make the connection. That said, I still question whether either ISR aircraft or scout corvettes have the signal processing power to cut through EW *at range*.

    4. " I still question whether either ISR aircraft or scout corvettes have the signal processing power to cut through EW *at range*."

      You've raised two issues: size of the platform and performance.

      1. Any ship, no matter how small (well, okay, not a rowboat) is far bigger than an ES-3A Viking or RC-135 or any of the ELINT aircraft. All of the equipment from all of those planes could fit easily on a very small vessel. Consider the size of the Pueblo, for example.

      2. Performance is the question. As with so much of our weapon systems, we've designed our ELINT with peacetime in mind. No one knows how these systems will perform in war. That said, passive systems should perform much better than active so I would hope that they would be reasonably effective in combat.

    5. "signal processing power to cut through EW *at range*. "

      Remember, EW is largely geared at jamming and signal disruption. It isn't generally intended to interfere with passive sensing because, hey, the sensor is passive so there's nothing to interfere with! Of course, an enemy could, and would, attempt to generate false signals but the effectiveness of that kind of effort is largely independent of range. General, wide spectrum electronic noise might be used to mask real signals but that requires immense power and would give away as much information as it hides.

      Bear in mind that I'm not an EW expert!

  6. A sensor ship like this could also act as a Electronic warfare ship (jam incoming enemy)or as an electronic decoy ship (pretend to be anything from a DDG to a CVG to draw attention away from real targets.)

    1. Bear in mind the concept of operations. This vessel would operate nowhere near a surface group so jamming would not be applicable. Further, active electronic warfare would give away the ship's position and the CONOPS calls for extreme stealth.

      Now, a somewhat similar vessel dedicated purely to electronic warfare that would sail with a surface group would nicely fit your idea and is well worth considering.

    2. Yes, but in both cases you are sacrificing a sensor platform for another mission. The enemy would send in a probing strike to try to get the pickets to radiate and then pick them off prior to the main raid being launched.

      Recon assets are incredibly important in warfare and are typically the first target of an enemy. As Tom Clancy wrote, "Everyone wanted to kill BEARs", referring to eliminating the Tu-95 recon planes that localized the targets for the Backfires.

      Which reminds me that in his scenario, the TU-95s used passive sensors and triangulation to locate the CVBG. They deployed on a line across the likely axis and stayed under the active radar horizon while using ESM to identify and localize emitters associated with the CVBG (Hawkeyes for example).

    3. I think the CONOPS is reasonably sound... While I dont like the idea of separating sensors from shooters in a localized BG defense, extending overall detection makes sense. Enlarging the envelope well past the E-2 sensor range allows them to be operated at reduced risk. Of course as EW(air or surface) pickets, theyd absolutely have to live under stringent EMCON, only using burst transmissions for relaying info back to other assets in a group (E-2s). Scheduled transmission timing, contact level confidences, etc being a function of tactics to evolve.
      I would avoid combining air and ASW missions though. Modern, semi-stealthy SURTASS built in meaningful numbers, directing SSNs is the way to go. Of course we need to learn to build relatively cheap single purpose ships with nothing more than robust point defense again for these ships...
      And while Im still sceptical about unmanned systems, what about current drone systems (Predator)? Could they carry the S-3 pods, and be launched from the pickets? How detectable are they? Would their extending the picket radius further be worthwhile vs. their detectability as passive sensors?

    4. "I dont like the idea of separating sensors from shooters in a localized BG defense"

      You've completely missed the purpose of this ship - or, I failed to convey it! It is NOT intended to contribute to battle group defense, at all. It is intended to provide situational awareness for OFFENSIVE purposes. Where is the enemy so that we can plan how to attack him?

      "I would avoid combining air and ASW missions though."

      I would too! There is no air mission other than general situational awareness of where enemy air assets might be operating.

      " Could they carry the S-3 pods"

      If you're talking about the ES-3A, there were no pods. It was all antennae. If you're talking about the S-3 ASW, the operators, consoles, MAD, sonobuoys, torpedoes, antennae, etc. all comprised the ASW capability. No drone can replicate that.

    5. I dont like the idea of separating sensors from shooters in a localized BG defense"
      That was more a reference to previous conversations, that at first made me very skeptical of this. But after more thought it has tons of merit. Youre offensive use was clear, my response was not.
      Although to be fair, the use of data for offensive or defensive use is somthing that can change in a second considering how fast a battlespace can/will evolve today. Having said that, Id certainly rather be the initiator rather than reactor in said space!!

      "If you're talking about the ES-3A"... My mistake there... My thoughts there were just lofting the sensors, and adding another hundred or so miles to overall detection range. This would rely on the "network" that weve all decided is probably not reliable anyway. I did envision possibly storing the data to avoid transmitting it back to the ship and avoiding detection, akin to WWII aerial surveillance films(?) Analysis/action would be aboard picket ship. The lack or delay in real time might be too much though. It was just somthing that popped into my head and probably not worth much...
      This is a tough subject with so little information available on current capabilities!!

    6. " My thoughts there were just lofting the sensors"

      I hear variations of this theme all the time. What no one seems to consider is that we're trying to replace a ship's worth (or aircraft's worth) of equipment and people with a tiny drone. Let's take all the equipment, consoles, computers, operators, sensors, cables, power supplies, etc. and put them on a tiny drone. That's 5 lbs of shit in a 1 lb bag - it doesn't fit! Unless you're talking about a S-3 Viking size drone (in which case, just use the Viking!) it just won't fit. You could send a single sensor on a single drone (maybe, depending on the size of the sensor and the size/weight of the power supply (everyone forgets about that). Of course you'd need constant communications back to some analysis station so you'd need extensive communications equipment on the drone. You see where this is going, right? It's not as simple as just saying, "Let's put a sensor pod on a drone!".

      I don't mean to jump on you. I'm just illustrating the generic case that people tend to vastly oversimplify the engineering aspects and come up with ideas that just aren't feasible.

      It's good to think about these alternative ideas but it has to be done with some basic engineering realities kept firmly in mind.

    7. No offense taken. Youre right (about the power supply too haha) My knowledge about true capabilities, weights, ranges, etc are Arleigh Burke-ish... Lots of overall capability, but excell at none. Im still evolving from a "Red Storm Rising" mentality, but enjoy the exercises you put forth, and it makes me try to at least "enlarge the box"!! Ill work on trying to stay more educated/relevant/realistic before commenting!!!

    8. "Ill work on trying to stay more educated/relevant/realistic"

      One of the best things you can do when assessing an idea is to look for the nearest real match and then try to understand why it is/does what it is/does. For example, if you want to put a sensor pod on a UAV, look for any example of a pod of any sort on a real UAV and then look at that UAV's size/weight/range. That would give you a fairly good ballpark of what can be done.

      Don't let me discourage you from coming up with ideas. Instead, let me encourage you to do a bit more research so as to produce the best, most realistic idea you can.

    9. With todays glaring exception lol, you have!
      Research for these topics has become an enjoyable pastime.
      Thats much the reason my spin on the "Cleveland class?" discussion hasnt resurfaced yet. Ive been neck deep in Congressional and other technical reports, trying to glean meaningful figures and Im still juggling pages of numbers Ive been acquiring for the "Armor??" and AAW/ASW ship ideas...

    10. Regarding research, I would caution about depending exclusively on modern examples (and I know you're not). The amount of knowledge about combat and weapons systems that we've institutionally forgotten is staggering. I can't tell you how many people I encounter who truly believe that we can't put armor on ships because the weight would sink/slow the ship. They've completely forgotten that we routinely built heavily armored ships in WWII.

      So, by all means, look at modern examples but cross-check with older examples, as well.

    11. Hey CNO, how about a suggested reading list?

    12. Tethered drones get around the power issue, and would be a good place for a multi spectral sensor.

      Q. what should the cruise speed & range of the ship be ?

    13. "Hey CNO, how about a suggested reading list?"

      That would be everything you can get your hands on! Seriously, it all depends on what, specifically, you want to learn about.

      My three sources of information are modern (every report, blog post, testimony, Congressional hearing, etc.), historical (every book and account I can find), and experience (I've witnessed many actions, technologicl developments, acquisition programs, and policies).

      That combination of modern, historical, and experience gives me the all-encompassing knowledge and wisdom that readers are in awe of.

    14. "Tethered drones get around the power issue"

      There's no getting around the non-stealthy issue and giving away one's own location - unless you're aware of a stealthy blimp?

      I've also seen no evidence that elevation bestows any significantly enhanced PASSIVE sensor performance. It may - it sounds plausible - but I haven't seen any direct proof. Show me some proof. Lacking that, the drawbacks (non-stealthy) outweigh any slight sensor gain.

    15. Microwave signals are subject to the same kind of ducting you get with sound in the sonar world. There is a wealth of information available from decades of data gathered by AT&T and CN/CP Telecommunications on their transcontinental long-line links. Ducting varies by frequency, time of day, time of year and weather just to name a few variables.

      An aerostat would give you the same kind of advantages VDS does in the sonar world. You could "tune" the altitude to give yourself the best gain for the frequencies you are trying to analyze.

      I'm not clear on this, but I would start by looking for ways to make the envelope radar-transparent, while making the electronics enclosure radar-absorbing. The problem with radar-absorbing is that its heavily frequency dependent. Hence the issues with low-frequency radars defeating stealth aircraft as an example. Still, an interesting idea.

    16. Potential aerostat materials would include Polypropylene, nylon, polycarbonate, polythene, PVC, PTFE (Teflon). They are all quite transparent to RF energy until you get to very high frequencies, much higher than a typical search radar.

    17. George,

      Very good comments. You've offered information along with logical conclusions. I don't know if you're correct or not (no reason to doubt you) but you've laid out information that I and readers can research. You've furthered the discussion and that's the type of comment I love. Thank you and well done!

      What we still don't know is practical import. Some things have a theoretical effect but no practical impact. This may or may not be the case here. We have no idea. If you come across any practical data, let me know.

    18. Thank you. I have some practical experience with microwave ducting. We leased some of the CN/CP 300' towers with 12' dia dishes on them. These operate at +/- 6GHz. These links are good for 99.9995% reliability taken over a complete year, but a few days each year, either spring or fall, and always at dawn or dusk we would sometimes lose a link. Always when there was the highest differential between air and ground temperatures. The signal strength would drop by the order of about 1000X and we would lose the link completely. Normally no more than 2 or 3 minutes at a time. You could chart the signal strength and see the variability. Most of the time it wasn't severe enough to completely drop the connection.

      Now I don't know if the duct was causing the path to vary horizontally or vertically or both, but it was certainly moving by at least 100' over 30 miles to cause that impact.

      The Canadians and Australians are moving to an Israeli company for their new frigate EW refits. Elbit Systems. They have some data on their website.

      Looks like really nice equipment, very compact, screaming fast. The main difference between EW in my day and now is processing speed. We were only semi-automated, whereas the new gear is actually capable of tracking a frequency agile radio or radar signal in real time as it hops around. Amazing stuff!!

      To return to aerostats for a moment, there have always been a couple of major issues with them. They don't like flying in anything other than calm weather, and they are a real bear to launch and recover in less than ideal conditions. They also need a really big envelope to get much lifting capability from the helium.

      Helikites seem to have developed a work-around for some of these problems. I would love to get my hands on one to play with.

      To keep it stealthy I would suggest a fiber-optic data cable in the tether, with an onboard hydrogen fuel cell or similar powering the aerostat electronics package. Passive electronics in what is basically an antenna/pre-amp package doesn't need a huge amount of power. Using a metallic-core tether would blow your stealth out of the water, so to speak.

    19. Your first link, NATACS sounds very much like what's being proposed here. Of course, everything sounds great in a manufacturer's brochure! Still, it seems to largely fill the bill, conceptually.

      " The signal strength would drop by the order of about 1000X and we would lose the link completely."

      " The signal strength would drop by the order of about 1000X and we would lose the link completely."

      Fascinating. If I understand you correctly, you're saying that ducting was causing the normal signal to be deflected to the point that the signal was lost to the receiver? That's kind of the opposite of the type of ducting we hope for when looking for OTH signals but illustrates the "power" of ducting, nonetheless.

    20. Agreed. You've got to apply a pretty rigorous bs filter to brochures. But I think Aussie acquisition is fairly rigorous while the Canadian process is notoriously poor. So we'll see.

      Yes, ducting creates an deviated signal path that is no longer a straight line. In addition, you have ground reflections that can also be subject to ducting, and as previously mentioned, ionospheric reflection and troposcatter effects.

      Ground reflections are a particularly interesting problem. We used to use 3' dia antennas to fine tune height on the towers. Much lighter to work with. You would think that the higher the better, but that's not necessarily true. You have to be careful that your direct path and the ground reflection do not cancel each other out. Ideally, you either don't want a ground reflection at all, or you want it to reinforce your direct path signal. Unfortunately, multipath signals can end up quite "fuzzy" because of the variable time delays at the receiver which can cause problems with high speed data transmission.

      In summary, the ability to vary the height of an antenna can be a powerful, if somewhat unpredictable tool.

  7. I hesitate to say, "even the Navy wouldn't be so dumb" about not putting ESM on a scouting platform, but....

  8. I can see how the need for passive surface sensors to triangulate could fit the "Sprint and drift" (?) of ASW.

    If this is counter to the needs of long distance convergence zone detection then the separation of small ASW and scout ship does sound very sensible.

    An alternative concept could separate the surface and subsurface elements of the scout vessel. An ASW screen handling surface long range passive detection and smaller conventionally powered submarines handling the subsurface convergence zone detection. Massively stealthy and able to loiter on the periphery.

  9. Hmm you have a very interesting point an idea Why dont we simply convert lcs to unmanned vessels they have the size the capacity oh wait they would have to towed be cause their broke down but hey at least I was thinking of them

    1. I actually thought about the LCS for this role but the inherent lack of range and endurance rule it out - along with the mechanical issues you mentioned.

  10. The problem is once it gets too big or u install so much electronic gear, it gets heavy, bigger AND COSTLY! I would like to keep it mission specific, let's just say recon for starters...I guess you could spiral up the different versions but it just gets more expensive and you lose the "expendable" part...WIKI says a Visby is something like $180 million, I think that's the upper limit of "expendable" for me, hopefully some of the local point defense systems can protect it enough some of them survive.

    1. I didn't say we need to build a Visby. I said it's a good starting point. We need to take the stealth aspects of the Visby and modify to fit the mission. The kind of passive signals monitoring equipment we're talking about is cheap and small relative to Aegis/AMDR arrays. Remember, we fit much of this type of gear aboard a tiny airplane (ES-3A Shadow).

      I also never mentioned expendable. These are not expendable vessels, hence the extreme stealth and some self-defense.

    2. "Visby is something like $180 million"

      The other question is why are not firing everyone in charge of ship procurement at the USN and hiring the guys in Sweden who designed the economical and efficient Visby (and Gotland sub). OT for this discussion but as far as I can tell every LCS we buy is a waste of what one or two Visbys we could license build.

    3. "hiring the guys in Sweden"

      As we saw in the Visby post discussion, all is not rosy with the Visby program. The costs are misleading and they had their problems. Foreign ships look good to us because no one is examining and reporting on them like we do here in the US. If we could examine them and see the private/classified reports we'd realize that foreign ships have all the same problems. Foreign ships also play as many accounting games as the US Navy, if not more, so I'd take any cost figure with a gargantuan grain of salt.

      That said, Visby is certainly better value than the LCS - but, to be fair, what isn't?

  11. The Navy must have gained a great deal of knowledge from building and testing the Zumwalt. I hope they can move forward and use this experience to design and build a more useful ship. Your proposal for a picket ship sounds like a good fit for the generation 2.0.

    A much down-sized Zumwalt like ship should be easy to design and sized to fit the CONOPS as described. Following the principals used in the Visby, using composits to reduce RCS, would also enhance stealth.

    If there is an inherent stability problem with the Zumwalt, a redesigned hull could be employed to enhance sea-keeping.

    1. "The Navy must have gained a great deal of knowledge from building and testing the Zumwalt. I hope they can move forward and use this experience to design and build a more useful ship."

      That's hilarious! Consider this statement,

      "The Navy must have gained a great deal of knowledge from building and testing the LCS. I hope they can move forward and use this experience to design and build a more useful ship."

      As we now know, they used their LCS experience to build the Zumwalt - a ship with no main weapon, no close range AAW, questionable seakeeping, and hideous costs.

      So, while we'd like to believe the Navy will learn lessons, history states, with 100% certainty, that they won't.

    2. "A much down-sized Zumwalt like ship should be easy to design"

      Or … … … we could just start from a Visby as the basis of a design and avoid all the unknowns and questions surrounding the Zumwalt hull form. Is there something inherently appealing to you about the Zumwalt that makes you think it would make a better design basis?

    3. "Is there something inherently appealing to you about the Zumwalt that makes you think it is a better design?"

      No, I can't say that I like the Zumwalt better than the Visby. What I can say is that it is easy for me to critisize the Navy but, I try to come up with a solution for the problem or at least try to add something new to the conversation.

      Oddly enough, my first thought when I typed Zumwalt was nearly the same as your response. However, I realized that a great deal of money and time had been spent on the Zumwalt and there is no reason to lose the lessons learned.

      Also, you had already named the Visby as a good starting point, so I was trying to name another possible ship that meets the requirements:)

    4. "Also, you had already named the Visby as a good starting point, so I was trying to name another possible ship that meets the requirements:)"

      That's fine. I just see nothing that makes the Zumwalt a good starting point. Its seakeeping is a potential drawback, for one thing. I suspect, based on what I've read, that the Zumwalt hull form, when scaled down, would be even less seaworthy than the full size Zumwalt in that it would be more susceptible to quartering seas. The Navy's scale testing of the hull form seemed to show this.

      But, hey, I'll leave final hull selection to the naval designers!

  12. This comment has been removed by the author.

    1. Your suggestion is valid for peacetime but not for war. During war, the deception attempt is pointless. Given the CONOPS, a "commercial" vessel hanging around the periphery of a combat zone is going to be instantly identified as military target.

    2. That was why I had already deleted it...I forgot to put the "peacetime" caveat in the text.

    3. Fair enough. I guess I responded too quickly!

  13. While more expensive than your E-corvette, another possibility is a small air-independent equipped diesel sub. It would be focused entirely on Recon/SIGINT, so it would only need a couple torpedo tubes for defensie or launching small USV’s and a lockout chamber for divers (and of course the SIGINT equipment). Our present nuclear subs provide this function now and go a great job but in wartime the Nuc’s would be needed for engaging the enemy. A scout sub could take over the intel missions and perhaps some of the Seal delivery missions.
    Non-nuclear, small size (perhaps twice the size of the NR-1), and it doesn’t need to be deep diving. In a sane world therefore it should not be prohibitively expensive. Of course the procurement in the last 10 years has been anything but sane.

    1. I'm dubious that sufficient size/weight of sensors could be deployed. You seem to be suggesting that tiny unmanned surface vessels launched from torpedo tubes (that is small !) would carry the sensors. That is really limited payload and I suspect it would not be adequate.

      How would the data be transmitted back to the sub?

  14. As I suggested on "Air Force Declines To Buy Light Attack Aircraft", an airship like the CL-160 would have been ideal. It would combine high indurance, heavy payload (for large sensors), and adaptability. It could even do self-defence, if the ESSM were modified for air-launch.

    It would be better than any ship, for long-range recon.

  15. No the usv's wouldn't be the sensor fit. they would be for tasks like tapping undersea cables. The sensor fit would be mast mounted like the AN/BLQ-10 in the Virginia class. That's how current nuclear subs do it. As small as the radar signature of a Visby may be, a submerged sub at mast depth would be vastly smaller.
    I was off with dimensions saying twice the size of NR-1 now that I reexamined the NR-1's stats, but I would still see it as slightly smaller than say the Dolphin class Israel is now fielding.

    1. You might want to look at the sensor fit of a ES-3A, RC-135, Pueblo, etc. The sheer number of sensors, antennae, and receivers is staggering. There is simply no way to fit all that on a periscope mast. Further, if sensor height is a factor, a sub mast has none.

      A submarine as a sensor platform is best used for a very specific, known target with a specific and limited data collection requirement. This would be the opposite of the proposal in this post.

  16. I like the idea, but as I understand it, the idea of a “stealth” ship is a misnomer. Reducing the cross-section of the ship is not the same as making it disappear. Enemy airborne assets will still be able to detect it at hundreds of miles away, even if it isn’t actively broadcasting. At best you’re going to blend in with smaller commercial vessels, but that isn’t going to be sufficient, especially in wartime. That means you will have corvette-sized ships with limited self-defense capability operating independently and hundreds of miles from the nearest friendly forces. These are going to get picked off very quickly.

    If we are serious about the concept (and I think we should be), we have to start optimizing submarines for these kinds of tasks. A “submarine” optimized for the surface instead of subsurface (e.g. moving away from the teardrop hull) would be a good start. The only truly stealth ship is one that can submerge.

    1. " Enemy airborne assets will still be able to detect it at hundreds of miles away"

      Well, no one actually knows detection ranges for stealth ships and anyone who knows, isn't saying. Still, most accounts suggest that a small corvette size stealth ship like the Visby would not be detectable 'hundreds of miles away', not even close. It will be detectable dozens of miles away as a very small boat (if you believe Visby's designers). During war, the enemy simply doesn't have the resources to go around checking out every small boat detection on the off chance that it might be a stealth ship. Even in war, the South China Sea will be very busy with fishing boats. People still have to eat!

      That said, the idea of a submersible surface ship is worth considering. There are a lot of physics challenges to such a design but it's worth a look.

    2. "" Enemy airborne assets will still be able to detect it at hundreds of miles away"

      Here's a quote from the previous post on the Visby and it gives detection ranges. You'll note that they are nowhere near "hundreds of miles"!

      “A stealth corvette of the [Visby] design has a detection range of 13km in rough seas and 22km in calm sea without jamming. In a jammed environment, the Visby would be detected at a range of 8km in rough sea and 11km in calm sea.”

    3. 22km... You are telling me a 240ft ship, with a 40ft mast, and a flight deck, is undetectable by radar outside of 22km? Does that even sound remotely feasible?

      CNO, you know way too much about radar to actually believe those numbers. I like the Visby, and the Swedes do have a reputation for being innovative, but at the end of the day the Visby is a ship with smoothed and angled sides, a copula for the gun, and an argyle paint job. It doesn’t have magical powers. Radar detection mostly comes down to shape, and the Visby has a freaking flight deck! You can’t just make that disappear.

      I’m fairly confident those numbers are detection ranges from a ship-based radar. They would make no sense otherwise. Even then, the claim is questionable. No one seems to be lining up to buy it, steal it, or reverse-engineer it, so either the technology is dubious or the concept is. My guess would be both.

      And yes, there will be lots of small ships still operating, and it only takes one of those small Chinese fishing boats to glance over and say, “that ain’t no trawler...” and make a radio call.

      Again, I like the concept, but don't see how it could work without the platform being able to fully submerge.

    4. "You are telling me a 240ft ship, with a 40ft mast, and a flight deck, is undetectable by radar outside of 22km?"

      I'm not telling you anything! I'm quoting a manufacturer's claim. You can rightly be dubious about the claim but it serves as a ballpark reference. Thus, your contention that a Visby can be detected at 'hundreds of miles' is likely incorrect. Where, between those two extremes, the actual detection point lies, who knows?

      For "proof" I look at what little known data there is. Large, non-stealthy ships are claimed to be detectable at 100+ miles by a variety of radars from a variety of manufacturers. Semi-stealth ships like the Burke are claimed to be 'orders of magnitude' less detectable or 'the size of a [unspecified size] fishing boat'. Presumably, that suggests that detection range for a Burke is on the order of, say 20-50 miles. It stands to reason, then, that a smaller, ultra-stealthy vessel like the Visby would be detectable at less than 20 miles, say 10-15 miles or so. This is in line with the manufacturer's claim.

      I also note that the realities of weather, wave clutter, sea state, etc. all act to degrade radar performance, thus enhancing a ship's apparent stealth and decreasing its detection range.

      Many manufacturer's claims are patently ridiculous and fly in the face of empirical evidence. The Visby stealth claim appears to be semi-reasonable. Even if you double the claimed detection range to 44 km (27 miles), it's still well shy of 'hundreds of miles'.

    5. " Visby has a freaking flight deck! You can’t just make that disappear."

      The question of horizontal surfaces and radar detection has long intrigued me. In very simplistic terms, stealth is determined by the reflection of incident radar waves. The best reflection (least stealth) comes from a 90 degree incidence. The least reflection (best stealth) comes, obviously, from 0 degree incidence. Thus, slanted sides are an attempt to avoid 90 degree reflections.

      So, for a ship to ship radar detection, a horizontal deck (or flight deck) is, essentially, a 0 degree reflection. For a aircraft (elevated radar) to ship detection, the horizontal surfaces represent around a 20 degree reflection - quite stealthy!

      In summary, unless the searching radar is directly overhead (giving it a 90 degree reflection), horizontal surfaces should be inherently pretty stealthy. Thus, a 'freaking flight deck' would seem to carry no stealth penalty.

      Let me close by reminding everyone that I am not a radar or stealth expert! I'm just applying common knowledge and common sense.

    6. The US has spent at least the last four decades developing stealth research and technology in the form of four different production aircraft models. Russia has been working to reverse engineer it for at least a decade. China stole much of the technology and has incorporated it into at least two aircraft designs (and counting). A dozen allied countries are either investing with the US or buying the stealth aircraft it is producing. Regardless of one’s opinion on the merits of stealth aircraft, everyone in “the know” (i.e. dozens of military-minded countries) have collectively spent trillions of dollars trying to incorporate it into their military equipment.

      Compare that to ships. The Visby class has been around for two decades. Dozens of classes and hundreds of ships have been built during that time, and none have gone “all-in” on a stealth ship. Instead, they mostly look to incorporate “stealthy” features which makes the ship appear smaller on radar (not makes it disappear). No other countries are trying to build it, buy it, reverse engineer it, or steal it. Does it seem reasonable that Sweden was able to achieve stealth on a 600 ton ship (20 years ago) when the rest of the world has been struggling to achieve it on something that is only a fraction of the size? It doesn’t past the smell test.

      As I said, the numbers you quote are almost certainly detection ranges from another ship. For a more accurate rough estimate, I would look at the reduction in range as opposed to raw numbers. Normal ships can be detected at around 20 miles. If the numbers are right and the Visby can be detected at 14 miles (22km), we can figure a 30% reduction in detection range. Airborne assets can detect normal ships at approximately 200 miles. A 30% reduction would be approximately 140 miles. I'm still skeptical "detection" means seeing a smaller ship versus seeing nothing. I suspect the manufacturer might mean ID when they say detect.

      Regardless, a sub is a vastly superior platform for this purpose and I would be interested to hear what "engineering challenges" you foresee.

    7. "Does it seem reasonable that Sweden was able to achieve stealth on a 600 ton ship (20 years ago) when the rest of the world has been struggling to achieve it on something that is only a fraction of the size? It doesn’t past the smell test."

      The Navy's Sea Shadow, built in 1984, was reported to be the closest thing to invisible to radar that there could be. Sea Shadow was around 170 ft long versus Visby at around 230 ft. Visby has the same basic stealth shaping as Sea Shadow so I see no reason to think that Visby is anything other than very stealthy, just as the manufacturer claims.

      We see, then, that very good stealth was achieved back in the 1980s. Why it hasn't been more aggressively pursued, I don't know but Sweden chose to do so.

      There are other stealthy vessels out there. The current Chinese Type 022 missile boat is reported to be very stealthy and, indeed, has much in common with Visby as far as shape. The Navy's own Zumwalt is supposedly quite stealthy and, again, shares the common angular shaping with minimal protuberances. Taiwan has built a 200 ft Tuo Chiang class corvette with extreme stealth. The Finnish Hamina class missile missile boat is reportedly very stealthy. And so on. Examples abound. The world is aggressively pursuing stealth ship designs and each new ship design is, generally speaking, more stealthy than the preceding one.

      I've laid out the logical case for accepting the manufacturer's claims to a reasonable degree. Unless you have some actual data that contradicts this, I've got to stick with my previous discussion.

      You clearly don't believe in the effectiveness of naval stealth but I urge you to evaluate the little evidence and logic there is rather than just relying on your gut feeling or whatever. Go where the data leads you.

    8. "At about 8:15 pm local time, with a range of about 8 miles (13 km) several missiles were launched. According to Lieutenant Colonel Đorđe Aničić, who was identified in 2009 as the soldier who fired the missiles, they detected the F-117 at a range of about 23 km operating their equipment for no more than 17 seconds to avoid being locked on to by NATO anti-air suppression. According to Dani in a 2007 interview, his troops spotted the aircraft on radar when its bomb-bay doors opened, raising its radar signature."

      That bomb-bay door is about the size of a twin mattress. Take a look at the picture you posted of the Visby. There are no less than a dozen objects protruding from the ship, including radars, antennas, fencing, towers, etc.

    9. You're cherry picking information. Out of all the examples of F-117's flying into heavily defended Iraq during Desert Storm, you've picked the only example ever recorded of a radar seeing an F-117. Further, you failed to mention that the F-117 was flying the same route day after day and the radar unit in question was able to predict and, according to reports, practice the actual engagement over days or weeks. The F-117 was also the very earliest example of stealth. One has to assume that stealth has improved over time.

      I've laid out a reasonable solid case for the effectiveness of naval stealth and it's clear that you simply don't want to believe the logic of naval stealth or the small amount of data that's available. So be it. You're welcome to your opinion. Time to move on.

    10. Very well. As a departing thought, I would encourage you to consider why you are making favorable assumptions (15-mile detection range from airborne radar) when the manufacturer makes no such claim. Assuming favorable details to shoehorn the viability of creative concepts is always a danger (I’m certainly guilty of it more times than not), and it seems to me you may be making that mistake in this instance.

  17. The M80 Stiletto demonstrator scaled up to 400 tons or so would give an American designed stealth ship that would be stable in high seas and at high speeds. The phrase “high speeds” generally leaves a bad taste in my mouth after the LCS debacle, but perhaps useful in egress from danger as your scout ships are not meant to go head-to-head in offensive combat. It’s composite structure might be retained to both keep down the RCS and also give some protection against detection by magnetic sensors and mines. It is very beamy in design so large passive sensors might be mounted on the sides and front of the hull with the center of the ship having the CIC/Signal processing center.

    Speaking of combat, what kinds of defensive armament/sensors would you think of as a standard fit for a Scout Ship? With the Stiletto design I would place a SeaRam on each corner in a semi-recessed (stealthy) position, a small (8 cell) vls in the center of the ship with sea sparrow quads, and perhaps a pair of 30mm fore and aft to deal very small patrol vessels/swarm boats. I’m afraid anything more than the defensive basics like this would lead to the navy making

  18. ...the navy making it into a nano-Burke the way the FFG(X) is becoming a mini-burke. (My comment got cut off somehow)

    1. Yes, the M80 might make a suitable basis for a scout ship. The rear and sides appear to be only moderately stealthy but that could be modified, if necessary. The vessel appears to lack the hull depth for VLS but I'm not sure. Adding weapons would likely compromise stealth given the lack of superstructure to "hide" them in. Still, worth examining.

      Scout ship defensive armament would be SeaRAM, CIWS, and possibly ESSM depending on size/space/weight allowances.

    2. A tactical length VLS--which could only fire ESSM would probably work.

      Of course the Navy turned what might have been the best candidate for a scout into scrap back in 2012--The IX529 Sea Shadow. Stealthy, SWATH stability, and just plain sexy.

  19. USNI has a public article about USV that complements your post. The article is entitled Two Birds with One Stone: A New Patrol Craft and Unmanned Surface Vessel and is worth a read.

    I found this passage most relevant to your post as it somewhat matches the scout ship you propose.

    "A ship-design study sponsored by the Chief of Naval Operations’ Surface Warfare Directorate describes a significantly more capable USV than even the Sea Hunter. The proposed 318-ton vessel would carry a hull-mounted sonar, air/surface search radar, soft-kill self-defense system, and a Mk-56 vertical-launch system, while also having a 10,000 nautical mile-range and 60-day endurance.6 Similarly, the Strategic Capabilities Office, in coordination with the Navy’s Unmanned Maritime Systems Office, explored the availability of a USV with a 4,500 nautical mile-range, 30-day endurance, 27-knot top speed, redundant propulsion, and 20 tons of mission payload."

    The above USV is lighter in displacement and appears to lack passive sensors in the your proposal, but its an interesting proposal. A USV that can self-deploy and operate independently for many weeks at a time is a must.

    1. Yes, that might make a suitable basis for a scout ship.

  20. Here is an interesting data point (and visualization) regarding the Visby class. I don’t know the relevance at longer distances, but still cool to see the difference on an actual radar.

    1. That's a fascinating graphic. Thanks for the link. A couple of thoughts.

      1. It confirms what we've discussed in various posts and comments that stealthy ships are, indeed, stealthy to some degree. That will make our surveillance and targeting more challenging as opposed to so many people who claim that the F-35, for example, will cover the hemisphere with a single pulse and identify every object there is.

      2. The Visby return appears to be around 1/5 - 1/10 of the unknown cargo ship size. The Visby is around 230 ft long. The cargo ship could be anywhere from 100 ft - 1000 ft. So, the Visby, even without any stealth shaping, would likely be 25%-50% of the radar return of the cargo ship just based on size difference. The return seems smaller than that which is, presumably, due to the stealth. The point I'm trying to make is that the return size difference is not just due to stealth but also, likely, to a real difference in size.

      Of course, it is also possible that the Visby return is being artificially enhanced for navigational safety sake and that the real return is even smaller!

      It would be far more interesting to see the Visby return from a military radar!

  21. I agree it gives a positive impression for stealth. There are a couple of other specs on the radar around the same size, so at the very least it helps the Visby blend into a larger population of ships.

    The orientation seems telling as well about which part of the Visby is registering on radar. Although the Visby looks perpendicular in the photo, that is not at all clear on the radar image, with the width of the ship being registered much more than the length.


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