tag:blogger.com,1999:blog-5579907756656776056.post6290165828992788341..comments2024-03-28T07:56:09.239-07:00Comments on Navy Matters: Scout ShipComNavOpshttp://www.blogger.com/profile/09669644332369727431noreply@blogger.comBlogger76125tag:blogger.com,1999:blog-5579907756656776056.post-59263248338567957852019-12-22T09:46:06.992-08:002019-12-22T09:46:06.992-08:00I agree it gives a positive impression for stealth...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.<br /><br />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. Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-11357997921610869802019-12-22T07:42:09.723-08:002019-12-22T07:42:09.723-08:00That's a fascinating graphic. Thanks for the ...That's a fascinating graphic. Thanks for the link. A couple of thoughts.<br /><br />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.<br /><br />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.<br /><br />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!<br /><br />It would be far more interesting to see the Visby return from a military radar!ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-171516801584501672019-12-22T05:36:41.558-08:002019-12-22T05:36:41.558-08:00Here is an interesting data point (and visualizati...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. <br /><br />https://www.reddit.com/r/navy/comments/e34k6w/demonstration_of_visby_corvettes_stealth_15m_away/Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-19114874663107639692019-03-03T06:58:50.061-08:002019-03-03T06:58:50.061-08:00Very well. As a departing thought, I would encoura...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.Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-13936016176272537202019-03-03T06:29:04.205-08:002019-03-03T06:29:04.205-08:00You're cherry picking information. Out of all...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.<br /><br />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.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-82684048851666883892019-03-02T20:57:25.184-08:002019-03-02T20:57:25.184-08:00"At about 8:15 pm local time, with a range of..."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."<br /><br />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. Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-78914430617355602902019-03-02T19:35:21.616-08:002019-03-02T19:35:21.616-08:00"Does it seem reasonable that Sweden was able..."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."<br /><br />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.<br /><br />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.<br /><br />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.<br /><br />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. <br /><br />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. <br />ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-79535851784575015392019-03-02T18:54:34.707-08:002019-03-02T18:54:34.707-08:00The US has spent at least the last four decades de...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. <br /><br />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. <br /><br />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. <br /><br />Regardless, a sub is a vastly superior platform for this purpose and I would be interested to hear what "engineering challenges" you foresee. Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-21199256894608852262019-02-28T07:21:48.749-08:002019-02-28T07:21:48.749-08:00Yes, that might make a suitable basis for a scout ...Yes, that might make a suitable basis for a scout ship.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-36604699281927081092019-02-28T07:20:45.553-08:002019-02-28T07:20:45.553-08:00" Visby has a freaking flight deck! You can’t..." Visby has a freaking flight deck! You can’t just make that disappear."<br /><br />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.<br /><br />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! <br /><br />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.<br /><br />Let me close by reminding everyone that I am not a radar or stealth expert! I'm just applying common knowledge and common sense.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-89772124314824690792019-02-28T07:14:28.387-08:002019-02-28T07:14:28.387-08:00"You are telling me a 240ft ship, with a 40ft..."You are telling me a 240ft ship, with a 40ft mast, and a flight deck, is undetectable by radar outside of 22km?"<br /><br />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?<br /><br />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.<br /><br />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.<br /><br />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'.<br />ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-31048876673672632232019-02-27T22:37:34.031-08:002019-02-27T22:37:34.031-08:00USNI has a public article about USV that complemen...USNI has a public article about USV that complements your post. The article is entitled <a href="https://www.usni.org/magazines/proceedings/2019/february/two-birds-one-stone-new-patrol-craft-and-unmanned-surface" rel="nofollow">Two Birds with One Stone: A New Patrol Craft and Unmanned Surface Vessel</a> and is worth a read. <br /><br />I found this passage most relevant to your post as it somewhat matches the scout ship you propose. <br /><br />"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."<br /><br />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. <br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-74959897447946795052019-02-27T21:17:34.871-08:002019-02-27T21:17:34.871-08:0022km... You are telling me a 240ft ship, with a 40...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?<br /><br />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. <br /><br />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. <br /><br />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.<br /><br />Again, I like the concept, but don't see how it could work without the platform being able to fully submerge.<br />Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-28797876395231235892019-02-27T17:58:29.911-08:002019-02-27T17:58:29.911-08:00"" Enemy airborne assets will still be a..."" Enemy airborne assets will still be able to detect it at hundreds of miles away"<br /><br />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"!<br /><br />“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.” ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-74832740468225528692019-02-27T11:55:51.510-08:002019-02-27T11:55:51.510-08:00A tactical length VLS--which could only fire ESSM ...A tactical length VLS--which could only fire ESSM would probably work. <br /><br />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.Johnnie Zhttps://www.blogger.com/profile/06943393440234157180noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-83434019706844597522019-02-27T11:22:46.202-08:002019-02-27T11:22:46.202-08:00Yes, the M80 might make a suitable basis for a sco...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.<br /><br />Scout ship defensive armament would be SeaRAM, CIWS, and possibly ESSM depending on size/space/weight allowances.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-56780317192123222442019-02-27T10:49:05.794-08:002019-02-27T10:49:05.794-08:00...the navy making it into a nano-Burke the way th......the navy making it into a nano-Burke the way the FFG(X) is becoming a mini-burke. (My comment got cut off somehow)Johnnie Zhttps://www.blogger.com/profile/06943393440234157180noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-70831258114492200652019-02-27T10:47:00.743-08:002019-02-27T10:47:00.743-08:00The M80 Stiletto demonstrator scaled up to 400 ton...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. <br /><br />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 <br />Johnnie Zhttps://www.blogger.com/profile/06943393440234157180noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-37636993325433163002019-02-27T09:30:32.801-08:002019-02-27T09:30:32.801-08:00" Enemy airborne assets will still be able to..." Enemy airborne assets will still be able to detect it at hundreds of miles away"<br /><br />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!<br /><br />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.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-16820595122844241952019-02-27T08:54:15.047-08:002019-02-27T08:54:15.047-08:00Agreed. You've got to apply a pretty rigorous ...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.<br /><br />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.<br /><br />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.<br /><br />In summary, the ability to vary the height of an antenna can be a powerful, if somewhat unpredictable tool. Georgehttps://www.blogger.com/profile/17731178888696691472noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-77242073924004123202019-02-27T08:37:07.436-08:002019-02-27T08:37:07.436-08:00I like the idea, but as I understand it, the idea ...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. <br /><br />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. Globe345https://www.blogger.com/profile/03839837937157991647noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-27868460696670494572019-02-26T19:56:03.698-08:002019-02-26T19:56:03.698-08:00You might want to look at the sensor fit of a ES-3...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.<br /><br />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.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-2076062408344662652019-02-26T19:48:04.193-08:002019-02-26T19:48:04.193-08:00No the usv's wouldn't be the sensor fit. t...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. <br />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.Littorally or Figurativelyhttps://www.blogger.com/profile/18163975830269552279noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-61933183805810696352019-02-26T16:33:26.080-08:002019-02-26T16:33:26.080-08:00As I suggested on "Air Force Declines To Buy ...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.<br /><br />It would be better than any ship, for long-range recon.Steven Seargeanthttps://www.blogger.com/profile/03129427781065451882noreply@blogger.comtag:blogger.com,1999:blog-5579907756656776056.post-76343992570082025922019-02-26T15:04:53.120-08:002019-02-26T15:04:53.120-08:00Your first link, NATACS sounds very much like what...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.<br /><br />" The signal strength would drop by the order of about 1000X and we would lose the link completely."<br /><br />" The signal strength would drop by the order of about 1000X and we would lose the link completely."<br /><br />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.ComNavOpshttps://www.blogger.com/profile/09669644332369727431noreply@blogger.com