Ship Stealth and Visby

Naval warship stealth is one of the most difficult things to find any data on.  The best information in the public domain consists of nothing more than vague statements like, “smaller radar cross section than a fishing boat”.

Ship stealth consists of more than just radar signature.  Stealth encompasses various aspects, including:

• Radar
• Infrared
• Magnetic
• Acoustic
• Wake
• Visible Light
• Electromagnetic

One of the few vessels that claims to be stealthy and has even a bit of descriptive information is the Saab/Kockums Visby class corvette.

The Visby class corvette is claimed to be the first vessel in the world to have fully developed stealth technology.

“The outstanding stealth properties fundamentally change the ship's survivability and improve its mission effectiveness.” (1)

“Flat surfaces and concealed equipment reduce radar signature to a minimum. The hull is designed on stealth principles with large flat angled surfaces. Every feature that need not necessarily be located outside the hull has been built in or concealed under specially designed hatches.” (1)

The concealed nature of much of the ship’s equipment is a noteworthy aspect.  It has been used on other ships but seldom to the degree that the Visby does.

Naval Technology website quantifies the radar detection range of the Visby.

“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.” (2)

Saab suggests that the vessels small radar cross section (RCS) is due, in part, to the material of construction.

“The vessel is built of sandwich-construction carbon fiber reinforced plastic (CFRP). The material provides high strength and rigidity, low weight, good shock resistance, low radar signature and low magnetic signature. The material dramatically reduces the structural weight (typically 50% of a conventional steel hull). This results in a higher payload carrying capability, higher speed or longer range.” (1)

The carbon fiber material has the added benefit that it conducts electricity and functions to shield radio signals from the ship. (3)

It remains to be seen how the material behaves in combat damage situations.  Does it fracture, does it produce toxic fumes when burned, does it propagate fire, can it be repaired at sea, etc.?

Visby Class Corvette

Other, seemingly minor, aspects of the ship’s radar signature have been minimized.

“Many less noticeable aspects include the coating of the bridge windows with indium tin oxide and gold which prevents radar returns from objects inside. Hatches and vents are also adapted with things such as a honey comb grid which also prevents returns, while radar absorbent materials have also been added in selected areas. The antennas are retractable into the hull as are the floodlight and fog horn, and even the navigation lights have been adapted to not stand out. They are fitted with quadruple redundant LED lights to avoid giving off a heat signature which brings us to the next point.” (3)

“The paint of the ship’s hull has also been specifically developed to reduce the IR signature.” (3)

Radar cross section is not the only stealthy aspect of the ship’s design.  The turbine exhausts have been relocated from the traditional upper superstructure location to the stern and use water injection to lower the exit temperature.

“The gas turbine exhausts have been concealed in hidden outlets close to the water surface at the stern of the vessel.” (1)

“… the exhaust is water injected which brings down the temperature to just above room temperature before the exhaust exits the hull.” (3)

One can’t help but wonder if the location of the exhausts to the stern is a wise idea.  If a missile does manage to home in on the exhaust, it will hit the stern and cause almost certain loss of propulsion and probably fatal flooding.  On the other hand, if the location combined with the water injection are sufficiently effective then a major heat source has been nearly eliminated.  Unfortunately, I have been unable to find any actual data regarding the thermal reduction effectiveness.

Magnetic signature has also been carefully addressed via an active, dynamically adjusted degaussing system.

“…  the ship has been fitted with an extensive degaussing equipment which renders it without a magnetic signature detectable by a mine. This is achieved by fitting degaussing coils throughout the ship which compensates for the magnetic signature of the on-board equipment. These are laid out in an X, Y and Z grid – the equipment also measures the earth’s magnetic field and compensates for this by adjusting the power to the degaussing system. The larger coils can however only manage the ship as a whole. There are specific steel objects that needs separate degaussing setups fitted. Engines, generators and gearboxes among other things.” (3)

The salient point to all of this discussion is the attention paid to every aspect of the ship’s stealth and the degree to which stealth was pursued.  The American Burke or LCS classes, by comparison, have only rudimentary stealth measures applied, mainly in the form of structural shaping (sloped sides).

Saab presents a fascinating series of photos related to warship stealth which illustrate their claims about ship stealth.

Here is a photo of a U.S. F-117 stealth fighter.  Note the flat, angular panels and lack of protuberances.

Now, here's a photo of the Visby.  Again, note the flat, angular panels and lack of protuberances.  The similarity to the F-117 is striking.

Finally, here is a photo of a U.S. LCS (Freedom class).  The Navy claims that the ship is stealthy but note the many protuberances, round domes, bits of deck equipment, exposed electrical junction boxes, antennae, etc.

Compare the number of projecting bits of equipment in the bow-on photo of the LCS versus the bow shot of the Visby.  It’s clear which one was serious about signature reduction!

Now, the key question is whether the extreme stealth measures of the Visby are worth it.  For example, if the Burke and LCS can’t be detected until the searching platform is within visual range then any further signature reduction – ala the Visby – serves no practical purpose.  Common sense would suggest that the Visby’s extra stealth measures are worthwhile but without data there is just no way to know.

The related question is what impact the Visby’s stealth measures have on the various ship’s system performances.  If the price of some extra stealth is poorer sensor performance, reduced weapon effectiveness, greater difficulty shiphandling, more mechanical problems associated with hidden doors and such, less efficient propulsion performance, etc. then these negative impacts would have to be weighed against the benefits of some incremental improvement in stealth.  Again, without data we just can’t make any judgments.

Regardless, it’s fascinating to see what a maximum, operational, stealth ship looks like and how it’s designed.

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(1)Saab website,

https://saab.com/naval/submarines-and-warships/naval-surface-ships/visby-class-corvette/

(2)Naval Technology website,

https://www.naval-technology.com/projects/visby/

(3)Task Force 72 website, “The Swedish Visby Class Corvette”, Craig Taylor, 18-Nov-2017,

https://taskforce72.org/2017/11/18/the-swedish-visby-class-corvette/

ESSM Test Firing

The Navy is excited about the first live fire test of an Evolved Sea Sparrow Missile (ESSM) Block II which just recently occurred.  The Block II incorporates an active guidance seeker in addition to the legacy semi-active seeker of the previous version.  In the test, the ESSM Blk II successfully intercepted a BQM-74E drone target.  The BQM-74E is a subsonic drone with a max speed of around 500 kts at sea level.

Okay, so what’s noteworthy about this?  The noteworthy part is the extent of the test program, or lack thereof.  From a USNI News article,

“The recent test follows two June 2017 Controlled Test Vehicle flight tests to prove the missile’s ability to launch. Four additional live fire tests will follow, ahead of starting production of the Block 2 missile.” (1)

So, a grand total of five live fire tests will be conducted prior to beginning production.  Does that really sound sufficient?  Will five tests really prove out the reliability of the missile, the performance of the seeker under the hundreds of possible scenarios, the effect of an ECM/decoy environment on the seeker, the effectiveness of the seeker against supersonic missiles, the stability of the seeker in response to launch and Mach 4+ maneuvering stresses, etc.?

The simple lack of testing against a supersonic target would seem reason enough to delay production, wouldn’t it?

The Navy, in their zeal to enter production, is glossing over critical testing.  We’re putting essentially untested weapons into the fleet.  People are potentially going to get killed expecting this thing to work, only to be tragically proven wrong.

Come on, now, ComNavOps, you say, the ESSM has been around for quite a while and this is just a seeker head upgrade – no big deal and no big test program is needed.  Once a missile has been in service for a while we don’t really need repeats of extensive testing – there’s nothing else to go wrong and nothing else to find out.

Well, there’s a few things wrong with that.  First, while I don’t have the data, I’m pretty sure the original testing program was far from extensive.  For example, I don’t recall off the top of my head that the ESSM has ever been tested against a supersonic target drone.  Just as importantly, I know there hasn’t been enough testing to demonstrate overall missile reliability.

To illustrate the reliability concern, consider the Standard missile which has been around forever and, supposedly, thoroughly tested.  Guess what?  They keep blowing up!

• A Standard SM-2 Block IIIa blew up upon launch from a German frigate on 21-Jun-2018. (2)

• Previously, a Standard SM-2 Block IIIa blew up on launch from the USS The Sullivans (DDG-68) during a training exercise off of Virginia on 18-Jul-2015. (2)

In both cases, it appears that the rocket motor exploded.  Apparently, testing was insufficient to detect the rocket flaw and the missile was released into the fleet where it is now putting ships and personnel at risk.

Considering how few live fire tests are performed each year, even these couple of explosive failures are disturbing.

The point of this post is not the reliability of the Standard SM-2 Block IIIa missile.  I have no problem with failures.  That’s how you find problems and fix them.  The point is that without extensive testing, these kinds of problems can’t be found.  Five test launches is not enough to detect whatever problems are lurking in the ESSM – and they’re there - we just haven’t tested enough to see them.

This reluctance to test is typical of the Navy’s constant, on-going battle with DOT&E.  DOT&E wants to conduct proper testing and the Navy constantly wants to skip testing and rush weapons into production.  Recall that DOT&E had to go around the Navy to get the Navy to conduct shock tests on the LCS.  Remember the result of those tests?  Sure enough, the LCS failed and the tests had to be conducted at reduced explosive levels and the final tests had to be dropped due to the certainty of excessive, possibly fatal, damage.  And yet, the Navy keeps wanting to rush systems into production.

Everyone except the Navy is all too aware of the now legendary problem with the WWII torpedoes that the Navy refused to properly test.  Everyone except the Navy recognizes the wisdom of extensive and realistic testing.  Everyone except the Navy understands that it is far better to find problems in peacetime than during combat.

The Navy needs to put the ESSM through rigorous testing under realistic conditions and against supersonic target drones using evasive maneuvers and ECM. 

The Navy got people killed by not taking the time to train and certify personnel on the recent Burke collisions and now they’re failing to take the time to properly test the ESSM.  More people will die someday.  Why can’t the Navy learn its lessons?  Why do people have to die because the Navy won’t take the time to properly train and test?  CNO Richardson, this is directly on you.

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(1)USNI News website, “Evolved Seasparrow Missile Block 2 Successfully Intercepts Aerial Target in First Live Fire Test”, Megan Eckstein, 6-July-2018,

https://news.usni.org/2018/07/06/evolved-seasparrow-missile-block-2-successfully-intercepts-aerial-target-in-first-live-fire-test

(2)USNI News website, “Missile Explodes During German Frigate Training Exercise; Incident Similar to 2015 U.S. Navy Explosion”, Sam LaGrone, 27-Jun-2018,

https://news.usni.org/2018/06/27/video-missile-explodes-german-frigate-training-exercise-incident-similar-2015-u-s-navy-explosion

We've Been Warned

ComNavOps dislikes and avoids repeating other websites and blogs.  My goal is to add value to news via insightful analysis.  Sometimes, however, a blog offers something that is simply too good not to repeat.  Such is the case, today.

I’ve stated repeatedly that China is looking to expand not only out to the first island chain but well beyond, including, eventually, world domination.  Many people scoff at that – probably the same people who several years ago scoffed at the notion that China would capture the entire South China Sea – but history and China’s own words fully support my view.

Cdr. Salamander’s blog offers this quote from Captain Liu Zhe, the commander of China’s aircraft carrier.

“We firmly believe that the farther away from the territorial sea, the more secure the motherland will be behind, the world peace will be more of a guarantee.”

This is flat out stating that China is planning to expand past the first island chain.  We’ve already seen the first indications of China moving on the second island chain.  China has begun to set up its rationale for continued expansion by making claims on Japanese territory, preparing to establish a base on Scarborough Shoal, conducting state sponsored emigration to the Philippines with the goal of annexing the island nation when the population tilts sufficiently Chinese, and exploring the “validity” of second island chain claims in various academic and political writings.

In fact, taking the Captain’s statement to its logical conclusion, the only distance sufficiently far away from the motherland to absolutely guarantee China’s security is total global control which is exactly what I’ve stated is China’s ultimate goal. 

China is like President Trump.  You may agree or disagree with the President but you have to acknowledge that he is doing exactly what he said he would do.  We may not like what China is saying but they are doing exactly what they’ve said they would do.  They’ve said they’ll continue to expand so why would we think they won’t continue to do so?

As Cd. Salamander stated, we’ve been warned.

_________________________________

(1)cdr salamander blog, “Keeping an Eye on the Long Game: Part LXVIII”, 6-Mar-2017,

http://cdrsalamander.blogspot.com/2017/03/keeping-eye-on-long-game-part-lxviii.html

Government Run Shipyards

During various post discussions, we’ve occasionally kicked around the idea of government run ship building yards as an alternative to the high costs and low quality seen of late from the commercial yards.  The proffered theory has been that the government couldn’t do any worse and might be better.  Of course, the evidence is overwhelming that the government wouldn’t do a better job as demonstrated by the government’s failings at running the Post Office, Social Security, various welfare programs, Medicare/Medicaid, Obamacare, and so forth.  We now have a report from the GAO (1) regarding the material condition and state of the four existing government owned and operated shipyards (Puget Sound, Norfolk, Pearl Harbor, and Portsmouth) and it puts to rest any forlorn hope that the government could successfully run a shipbuilding yard.

To put it in a nutshell, the four shipyards are barely functional, ancient, decrepit, neglected, horribly maintained, and woefully underfunded.  This is the most direct evidence that the government would be incapable of successfully running a shipbuilding yard.

Let’s look a bit closer.

Why do we even have government owned shipyards?  From the GAO report,

“The naval shipyards are essential to national defense and fulfill the legal requirement for the Department of Defense to maintain a critical logistics capability that is government owned and operated to support an effective and timely response for mobilization, national defense contingency situations, and other emergency requirements.”

“The naval shipyards provide depot-level maintenance, which involves the most comprehensive and time-consuming maintenance work, including ship overhauls, alterations, refits, restorations, nuclear refuelings, and deactivations—activities crucial to supporting Navy readiness.”

These shipyards perform all the Navy’s nuclear maintenance activities.

Unfortunately, the yards are physically crumbling due to lack of care and concern on the part of the Navy.

“The Navy acknowledges that there has been a history of under-investment in shipyard restoration and modernization needs.”

Really?  The Navy recognizes that they have failed to maintain the material condition of the yards and yet has consistently opted not to remedy the situation.  That’s incompetence, gross negligence, and, given the critical nature of the services the yards provide to our national security, approaching treason.

Given the Navy’s failure, Congress has attempted to step in.

“Recognizing this issue, Congress passed a law in fiscal year 2007 that requires the Secretary of the Navy to invest in the capital budgets of the Navy depots a total amount equal to not less than 6 percent of the average total combined maintenance, repair, and overhaul workload funded at all the Navy depots for the preceding three fiscal years.”

I have no idea what dollar amount that works out to be but I doubt it’s anywhere near sufficient.

I trust this ends the argument that the government should operate naval construction shipyards?

(1)Government Accounting Office, “Naval Shipyards – Actions Needed To Improve Poor Conditions That Affect Operations”, Sep 2017, GAO-17-548

Dynamic Mongoose ASW Exercise

Norway is hosting a NATO ASW exercise, called Dynamic Mongoose 2018, described as the year’s largest ASW exercise in the North Atlantic.  Participants include Norway, Denmark, Germany, Poland, the Netherlands, Spain, Turkey, and the United States. Good thing, right?  Well, maybe not so right.  Look at the lineup for this exercise. (1)

• 7 surface ships
• 2 submarines
• 3 aircraft (one each from Germany, Norway, and US)

That’s the lineup for the “year’s largest NATO anti-submarine training in the North Atlantic”?  Three aircraft for the “year’s largest NATO anti-submarine training in the North Atlantic”?  Two subs?  Seven ships?  That’s a pretty pathetic effort.

Take away the token US contribution and the lineup is just 6 ships, 2 subs, and 2 aircraft from seven countries.  Seven countries could only muster two aircraft for the “year’s largest NATO anti-submarine training in the North Atlantic”?  That’s appalling.

This also highlights the weakness of many of the participating NATO members.  Norway’s entire navy, for example, consists of 5 frigates.  And so it goes.

I realize that most of these countries are fairly small but given their proximity to a militarily expansionistic and extremely aggressive Russia, I would think these countries would be wise to have much larger military forces.  I’m sure their thinking is that the US will defend them so any significant defense investment on their part is unnecessary.  That’s an attitude that the US needs to change.  We need to insist that they get serious about their own defense and this exercise is a perfect example of the problem.

I also realize that there are many exercises throughout the year and this may be a simple case of having to pick and choose which to attend but, really, is there any better use of time than actual, semi-realistic exercises?  Unless there are competing, concurrent exercises then there's no good reason not to attend this exercise in force - unless it's constraints imposed by operational budgets which would, again, go back to the degree of seriousness with which these countries are taking their defense responsibilities.

Now, any semi-realistic training (don’t know if this or not) is better than none but contrast this effort to a Russian exercise in the Barents at about the same time.

“A total of 36 warships and support vessels are currently on their way out to the Barents Sea. Also, about 20 aircrafts are in the air. Along the coast of the Kola Peninsula, more than 150 different rocket- and artillery weapon systems and special equipment are deployed.

Larger areas in the Barents Sea are now closed off for civilian shipping and overflights by civilian passenger aircraft. The drill will last until the end of next week. 

Among the warships are the missile cruiser Marshal Ustinov [Slava class], anti-submarine ship Severomorsk [Udaloy class], the destroyer Admiral Ushakov [Sovremenny class], the large landing ships Kondapoga, Georgy Pobedonosets and Aleksandr Obrakovsky.

Without specifying classes or names, the Northern Fleet says both nuclear-powered and diesel submarines participate.” (2)

Who’s more serious about combat readiness, Russia or NATO?  Seems obvious.

____________________________________

(1)The Barents Observer website, “Photos from NATO's anti-submarine warfare exercise outside Harstad”, Thomas Nilsen, 4-Jul-2018,

https://thebarentsobserver.com/en/security/2018/07/see-photos-natos-anti-submarine-warfare-exercise-outside-harstad

(2)The Barents Observer website, “Alarm-drill: 36 Russian warships sail out to Barents Sea”, Thomas Nilsen, 13-Jun-2018,

https://thebarentsobserver.com/en/security/2018/06/36-russian-warships-sails-out-barents-sea

USS Wasp - Small Carrier Experiment

The large carrier versus small carrier debate has raged, literally, since the first carrier was built.  However, every study ever conducted and every experiment attempted has demonstrated the superiority of the large carrier.  Let’s take a look at the first attempt by the Navy to build a small carrier, the USS Wasp, CV-7.

As a brief reminder, Wasp was laid down in 1936 and commissioned in 1940.  She initially served in the Atlantic, often performing ferry duty for Spitfires and, in fact, landed one Spitfire aboard without a tailhook during an aircraft emergency! 

USS Wasp

Wasp transferred to the Pacific in mid-1942 where she supported the Guadalcanal operation.  In late August 1942, Wasp’s air group consisted of 26 Grumman F4F Wildcats, 25 Douglas SBD Dauntlesses, and 11 Grumman TBF Avengers for a total of 62 aircraft, according to Wiki. 

Wasp was sunk on 15-Sep-1942 as the result of a spread of six torpedoes launched from a Japanese submarine, three of which hit the carrier.  Subsequent gasoline fires and internal explosions caused the ship to be abandoned.  She was eventually sunk by three additional torpedoes from a US destroyer.

Here some comparative size specs for the Wasp and her larger cousin the USS Enterprise, CV-6

                                  Wasp   Enterprise

Displacement, tons full load    19,000     25,000

Length, ft overall                 741        825

Beam, ft overall                   109        109

Air Group                     62(a)–71(b)      87(c)

Crew                             2,167      2,217

(a)     August 1942, Wiki

(b)     Time of sinking, Wiki

(c)     July 1942 – May 1943, (1)

We see, then, that Wasp was 76% the displacement of the Yorktown and 90% of the length.

In order to “fit” within the weight/size range, many aspects of construction and performance were compromised.  From Wiki,

“To save weight and space, Wasp was constructed with low-power machinery (compare Wasp's 75,000 shp (56,000 kW) machinery with Yorktown's 120,000 shp (89,000 kW), Essex-class's 150,000 shp (110,000 kW), and the Independence-class's 100,000 shp (75,000 kW)).

Additionally, Wasp was launched with almost no armor, modest speed, and more significantly, no protection from torpedoes. Absence of side protection of the boilers and internal aviation fuel stores "doomed her to a blazing demise". These were inherent design flaws that were recognized when constructed, but could not be remedied within the allowed tonnage.”

Let’s look at a few more specific aspects of the smaller design.

Flight Operations.  The purpose of a carrier is, of course, aviation and the Wasp’s small size impacted its aviation function.  Carriers of that time required sufficient wind over the flight deck to enable aircraft to take off and land and Wasp’s small power plant provided insufficient speed without the benefit of natural wind.  Further, the Wasp required a long period of time to attain maximum speed for take off and landing flight operations – a severe inconvenience in combat!

“… the combination of speed and flight deck size was critical.  The Wasp was deficient in both respects.” (2, p.114)

Crew Size – Despite being only 76% of the size of the Yorktown class (based on displacement), the Wasp required 98% of the crew size – almost no savings!  This would be a key consideration today given the Navy’s single-minded pursuit of the Holy Grail of reduced manning.

Air Group Size – The design scheme for Wasp envisioned an air group of 70 aircraft versus 90 for the Yorktown class. (2, p.89)  That would have given the Wasp an air group 78% the size of the Yorktown.  In practice, the Wasp’s air group was 71% - 82% of the Yorktown’s – a fairly linear reduction proportional to the displacement reduction.

Gasoline and Ammunition Protection – As it turned out, Wasp’s smaller size resulted in increased risk due to explosive aviation gasoline and ammunition.

“Both gas and ordnance allowances were proportional to the size of the air group, and hence to deck area rather than to displacement: a smaller carrier, which could not be so well protected, would actually have to carry a larger proportional tonnage of gasoline and ammunition than would one of her larger sisters.” (2, p.108)

So, the smaller size actually increased the risk due to stored flammable and explosive materials!

Wasp Sinking

On the plus side, the smaller carrier was able to operate an air group of sufficient size as to be operationally useful.  In addition, the smaller carrier did increase the overall carrier numbers.  However, in order to achieve these pluses, the ship was forced to incorporate many compromises and omissions when compared to the larger Yorktown class.  These shortcomings negatively impacted survivability and function and resulted in a ship that was operationally inefficient and combat fragile and, in the event, did not last long in combat.

Despite recognition of Wasp’s shortcomings, interest in small carriers did not die.

“Although the Wasp was acknowledged to be unsatisfactory from birth, interest in smaller carriers did not die off completely.  In 1938 Congress approved another 40,000 tons of carrier construction, tonnage eventually expended in the Hornet and the Essex.  There were, however, some who suggested that some of it go into 10,000-ton light carriers.  In November 1938 Admiral R.L. Ghormley of the War Plans Division wrote that a larger number of such smaller carriers might yet have its advantages, even though unquestionably the larger carriers would provide a greater economy of effort in tons of ship and number of ship personnel per plane carried.” (2, p.114)

Thus, even while unanimously recognized as inferior, the concept of small carriers continued to prove alluring and this allure continues through today, despite every study and experiment ever conducted.  Truly baffling.

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(1)http://www.cv6.org/company/airgroups.htm

(2)”US Aircraft Carriers – An Illustrated Design History”, Norman Friedman, Naval Institute Press, Annapolis, MD, 1983, ISBN 0-87021-739-9

New Page - Fleet Structure

Posts are inherently limited in length and this often leads to some confusion.  For example, the discussion about an ASW corvette lead many to believe that was the only ASW asset I envisioned.  Instead, it was just one of many assets but the only one I could discuss in the space allotted.   

To ease some of this confusion, I've published a page (see the tabbed menu across the top of the blog) with my proposed complete fleet structure and descriptions of individual elements.  With this, the reader can place any specific asset under discussion into the proper overall context.

Recognize that this fleet structure is subject to change as ideas are modified and refined.

I've omitted the entire logistics support fleet, at least for the time being.

I've proposed a two-tier war-peace fleet.  This page covers only the war fleet.

The page is intended as a reference and is, therefore, closed to comments but feel free to comment in this post.

Check it out and enjoy!