Submarines and ASW in the China War

The US military recognizes that the geography of the Pacific region dictates that a war with China will be a naval and air war.  What’s more, an astute - or just semi-literate – naval analyst will recognize that the war will be, substantially, a submarine war.  Of course, US Navy admirals do not qualify even for the semi-literate classification so who knows whether they recognize this or not?  Regardless, the rest of us recognize the primacy of the submarine in this conflict.  With that understanding, let’s take a closer look at  submarine warfare and its counter, anti-submarine warfare (ASW), in a war with China.

 

 

Numbers

 

The obvious starting point is numbers and both sides have submarines – something the US Navy seems to forget/ignore so let’s check each side’s respective submarine numbers.

 

China

 

China has around 64 submarines of all types with the majority being SSKs.  Excluding the SSBNs, the total is 56.  Obviously, it is very difficult to know exact numbers and there is some uncertainty about the active/inactive status of some vessels.  Acknowledging that, the numbers break down as follows:

 

 

Type	Class	Qty.
SSN	Han class (may be inactive/reserve)	3
SSN	Shang I class (Type-093)	2
SSN	Shang II class (Type-093A)	4
SSBN	Jin class (Type-094)	8
SSK	Ming class (Type-035)	4
SSK	Song class (Type-039)	13
SSK	Yuan class (Type-039A/B)	18
SSK	Kilo class (Project 877/Project 636/Project 636M)	12
	Total	64

 

 

In addition, China maintains many older SSKs in reserve status and these could play a pivotal role in a sustained war after both sides lose many of the front line submarines.

 

United States

 

The US currently has 68 active submarines that break down as follows:

 

SSBN 14

SSGN 4

SSN 50

 

Of course, unless we enter a nuclear war with China, the 14 SSBN are of no combat use which leaves us with 54 combat submarines compared to China’s 56. 

 

In addition, the US is still on the long anticipated downward trend which is projected by the Navy’s latest 30 year plan to bottom out at a low of 46 SSN in 2028 and will not reached a sustained 50+ level again until 2034.  This also assumes no additional early retirements – not a bet I’d care to take.

 

So, at the moment, the US and China have equal numbers of submarines with China being mostly an SSK force and the US being exclusively nuclear. 

 

 

SSK

 

United States naval observers keep clamoring for SSKs because they are so quiet and effective.  Turning it around, that must mean that Chinese SSKs are a major threat to us. 

 

Given the geography of the East and South China Seas, where combat can be reasonably anticipated to take place, China’s conventional submarines have significant advantages related to acoustics and stealth.  The traditional disadvantages of SSKs – range, endurance, low speed, etc. don’t really apply when operating so close to home ports.  Therefore, China, with a fleet of 47 SSKs enjoys a potentially significant tactical advantage, being able to saturate chokepoints and operating areas with extremely quiet, nearly undetectable submarines that suffer few of the SSK disadvantages.

 

Should the Chinese submarines attempt to venture out from the first island chain, the advantage would flip to the US with its nuclear subs.

Chinese Yuan Class SSK 

 

 

SOSUS

 

China has established a network of SOSUS-like listening arrays throughout the first island chain.[1, 2]  US submarines will have a difficult time penetrating the first island chain and operating undetected. 

 

On a related note, China has acknowledged having listening stations monitoring undersea activity around Guam.

 

The Chinese government has revealed the existence of two underwater sensors situated between the United States island of Guam and the South China Sea. …

 

The state-run Chinese Academy of Sciences only disclosed the pair of acoustic sensors earlier in January 2018, but had been operating them since 2016, according to a report from the South China Morning Post. One of them is in the Challenger Deep, located at the southern end of the Marianas Trench and the deepest known point on earth, and the other is situated further west near the island of Yap, part of the Federated States of Micronesia. Both reportedly can pick up acoustic signatures more than 620 miles away, putting them within range of Guam and the major strategic U.S. naval base at Apra Harbor.[3]

 

Similarly, the US and Japan have reportedly established a network of listening arrays throughout the first island chain and extending into the Indian Ocean.[4]  Chinese subs will have a difficult time operating undetected.

 

Since both sides operate listening arrays, this would seem to favor neither side.  However, the extreme quiet of the SSKs might seem to offer an advantage to China.

 

 

ASW

 

The US has much greater experience and institutional knowledge about ASW although the Navy seems intent on squandering that advantage by refusing to produce combat-effective ASW assets.  For example, the P-3 Orion was not suited to operating in contested areas and replacing it with the nearly identical P-8 Poseidon was foolish.  The LCS-ASW variant has been officially abandoned, leaving the Navy with no dedicated ASW surface vessel.  The Burkes, while ASW-capable, in theory, are woefully deficient in training and are far too expensive to risk playing tag with Chinese SSKs.

 

To compensate, the US needs to focus its submarine force o on ASW, dropping strike, ISR, special ops, and any other non-ASW mission.  This singular focus is necessary to produce maximum competency and thereby negate China’s SSK advantages.  New submarine designs and construction with this singular focus would have the effect of making subs cheaper (no VLS) and, therefore, more numerous.  It also makes them smaller and quieter.  All else being equal, smaller is harder to detect than larger.  VLS serves no purpose for the submarine’s main mission of ASW or even its secondary mission of anti-surface warfare.  If we want land attack subs then we should build dedicated SSGNs.

 

The US desperately needs to begin realistic, intensive ASW training using actual SSKs as enemy surrogates.  Some time ago we leased the services of an SSK for such training but we ended that practice and no longer have dedicated training against SSKs, as far as I know. 

 

Where is our Top Gun for submarines where dedicated enemy sub simulators and surrogates operated by exquisitely trained instructors specializing in enemy tactics teach submariners how the enemy will fight and how to defeat them?  We don’t have such training.  The Navy has made noises about establishing such an organization but has, thus far, failed to provide actual SSKs and dedicated OPFOR crews to man them.  Without that, any minor training efforts are just paper exercises.

 

Closely related to ASW training is the practice of anti-ASW, meaning the evasion and escape from, and defeat of, enemy ASW forces?  To the best of my knowledge we do not practice that at all.

 

 

Confined Waters

 

Confined, often shallower waters present unique characteristics when compared to the open ocean, deep sea waters that US submarines are used to operating in.  Salinity, density, thermoclines, depth, conductivity, acoustic propagation, etc. are all different inside the East and South China Seas.  This confers a familiarity that gives Chinese submarines a ‘home field’ advantage.  Are we actively and aggressively collecting data on the physical characteristics of the waters inside the first island chain?  I would hope so but I’m not aware of any sustained program along those lines.

 

The differing physical characteristics dictate different submarine tactics than those used in open ocean scenarios.  Are we practicing confined water (E/S China Sea) submarine tactics?  Again, I would hope so but there are no programs that I’m aware of.  While there may well be physical characteristics data collection that I’m not aware of, it is far less likely that there are tactics programs that I’m unaware of.  I know for a certainty that there is no equivalent to Top Gun.

 

 

 

Summary

 

Both sides have equal numbers of submarines with China leaning heavily towards SSKs while the US favors nuclear subs.  Both sides have listening arrays which possibly confers a slight advantage to the Chinese SSKs.

 

One would hope that we are diligently working on locating Chinese SOSUS arrays and have lans to destroy them at the outset of war.  Finding and planning/training for the Chinese SOSUS destruction would be a worthy mission for SEALS instead of being a land combat force in the Middle East.

 

Neither side possesses useful, tactically relevant ASW forces.  P-8s cannot survive in the anticipated operating area.  US surface forces are nearly inoperable as regards ASW.  When war comes we will not risk Burkes conducting ASW and, indeed, would be foolish to do so.  Burkes are nearly non-functional due to lack of training.  The LCS has been eliminated as an ASW asset. 

 

On the other hand, China is completely without submarine or ASW experience and likely has little acoustic data on US submarines.

 

The winner of the submarine/ASW fight will win the war and the winner will be the side that trains the hardest and most realistically.  While I have no knowledge about Chinese submarine warfare training, I can say that the US is not training hard, is not training productively, and is not training realistically.  That doesn’t bode well for us.

 

We just don’t seem to be serious about war.

 

__________________________________

 

[1]Forbes website, “China Builds Surveillance Network In South China Sea”, H. I. Sutton, 5-Aug-2020,

https://www.forbes.com/sites/hisutton/2020/08/05/china-builds-surveillance-network-in-international-waters-of-south-china-sea/?sh=68ef686d74f3

 

[2]http://www.hisutton.com/Cn_Underwater_Great_Wall.html

 

[3]Drive website, “China Reveals It Has Two Underwater Listening Devices Within Range of Guam”, Joseph Trevithick, 30-Jun-2019,

https://www.thedrive.com/the-war-zone/17903/china-reveals-it-has-two-underwater-listening-devices-within-range-of-guam

 

[4]https://defence.pk/pdf/threads/fish-hook-sea-bed-sosus-network.448398/

Missiles Versus Battleships

One of the common rejoinders employed by battleship critics is that modern anti-ship missiles would quickly and easily sink a battleship.  Of course, this statement is made with zero supporting evidence.  On the contrary, there is much evidence that suggests – but does not explicitly prove – that battleships would be largely immune to anti-ship missiles.

 

Battleship critics have suggested two modes of ‘killing’ a battleship:

 

• Outright sinking using modern anti-ship cruise missiles
• Mission killing due to destruction of top side electronics, sensors, and weapons

 

We’ll examine each of those modes but, first, let’s understand some underlying concepts.

 

 

Relevant Concepts

 

Armor Piercing Shells – A battleship’s main weapon was the 16”+ gun firing 2500 lb armor piercing (AP) or high explosive (HE/HC) shells travelling at velocities of Mach 2+.  For example, the Iowa’s 16” AP/Mk8 weighed 2700 lb and had a muzzle velocity of 2425 ft/sec (1653 mph, Mach 2.1).

 

What is an armor piercing (AP) shell?

 

U.S. Navy World War II nomenclature uses the words "Armor Piercing" (AP) to mean that the base-fuzed, hard-nosed projectile so labeled has a thick, steel AP cap designed to allow intact penetration through some thickness of Class "A" (face-hardened) armor plate.[1]

AP Shell Mk 8

Armor piercing shells were designed, as the name implies, to penetrate a ship’s armor.  This was accomplished by placing a heavy, solid metal cap over the explosive shell.  Grossly simplifying, the cap was a sacrificial ‘point’ that would penetrate the armor allowing the explosive shell behind it to enter the ship intact and functional before exploding. 

 

Armor – A battleship’s armor (we’re talking about US battleships in this post) is intended to protect vital equipment.  Any equipment not protected is not vital – useful, undoubtedly, but not vital.  As a general statement, battleship armor was designed to provide immunity to another battleship’s weapons which means 16”+ shells.  It is noteworthy that the Iowa class was designed to be immune to 16” plunging fire.

 

Armor was not, as so many people believe, simply thick plates of steel attached to the sides of the ship.  Instead, it was a sophisticated system of plates, layers, carefully calculated void spaces, differing materials and treatments of steel, calculated angles (obliquity), etc. all working together to defeat attacking shells.

 

The main mechanism of armor protection was the act of decapping incoming AP shells before they could penetrate the armor.  In other words, the armor was designed to strip the armor piercing cap off the incoming shell before penetration could occur.  If the shell could be decapped, the shell’s penetration would be prevented or severely limited.  Navweaps website has articles by Nathan Okun that go into much greater detail, for those interested.[1,2]

 

Armor penetration requires a rather lot of information, but decapping of the projectile by breaking the rather weak solder and/or mechanical bond between the nose and cap base is very, very simple:

 

0.08-0.08049-caliber thickness of any kind of homogeneous iron or steel plate has a 50% chance of decapping any kind of capped projectile over 40mm in diameter under ANY impact condition, penetrating or not.

 

0.0805-caliber and up thickness always decaps the projectile, penetrating or not.[2]

 

 

The USN Iowa and South Dakota class battleships have an internal inclined main armor belt. What isn't well known is that they also have a shell plating outside of this belt that acts as a decapping plate. On the South Dakota's, this shell plating is 1.25" thick (3.2 cm) and on the Iowa's it is 1.5" thick (3.81 cm). Using Nathan's formula above, the South Dakota's plating would be sufficient to decap any projectile up to 15.5" (39.4 cm) and the Iowa's plating would be sufficient to decap any projectile up to 18.6" (47.3 cm). This would imply that the Japanese Type 91 18.1" (46 cm) APC projectiles fired by the Yamato would be decapped by the Iowa's shell plating before they reached the main armor belt. Decapping an AP projectile greatly decreases their armor-penetration ability against face-hardened naval armor (unprotected projectile nose now shatters into pieces) at under 45° impact obliquity angle.[2]

 

 

The angle of impact (obliquity) of a shell on armor was also immensely important.  A perfectly perpendicular strike on armor was the most difficult to defeat while angled impacts acted to disperse the force parallel to the armor, causing a ricochet or greatly reduced damage.  This is why armor was angled when possible and where appropriate.  Again, I’m grossly simplifying the physics and mechanics of this. 

 

Another important factor that most people are unaware of is just how extensive the armor coverage was.  For example, the conning tower of the ship was heavily armored as opposed to today’s ships whose bridge superstructures are not armored at all and consist of what amounts to thin aluminum foil, for all practical combat purposes.  Note the thickness (17.3”) of armor around the conning tower of the New Jersey in the photo below.

 

Armored Conning Tower 

Critics who think a battleship’s topside would be destroyed by missiles are unaware of the extent of armor.  WWII ships were built with armored structures and equipment that we don’t even consider for armor today.  The topsides, while not protected as heavily as the hull, were still heavily armored.

 

One of the common misguided notions is that anti-ship missiles will conduct pop-up attacks and strike the vulnerable decks from above where the battleship is helpless. Battleships were design to defeat plunging fire.  From Wikipedia,

 

The deck armor consists of a 1.5-inch-thick (38 mm) STS weather deck, a combined 6-inch-thick (152 mm) Class B and STS main armor deck, and a 0.63-inch-thick (16 mm) STS splinter deck. Over the magazines, the splinter deck is replaced by a 1-inch (25 mm) STS third deck that separates the magazine from the main armored deck.[3]

 

Thus, overhead strikes were well accounted for with the upper deck providing the decapping function and the underlying deck providing the main resistance against whatever penetration did occur.  Of course, if it were established that overhead attacks were a common staple of missile attacks, a modern version of a battleship could easily redesign the armor to beef up that area.

 

Anti-Ship Missiles - Now that we understand what is required to have a chance of penetrating battleship armor (meaning an AP shell) and how the armor acts to protect the ship, let’s look at the modern ‘shell’ which is, of course, the anti-ship missile (ASM).  ASMs can be crudely grouped into two categories:

 

Light – typified by the Harpoon (1500 lbs, 490 lb warhead), Exocet (1700 lbs, 360 lb warhead), and C-80x family (418 lb warhead), among others.  These are relatively small, light, generally subsonic, and have warheads in the few hundred pound range.

 

Heavy – typified by the BrahMos (6600 lb, 660 lb warhead), P-700 Granit (15,400 lb, 1650 lb warhead), and P-800 Oniks (6600 lb, 660 lb warhead).  These missiles are relatively large, heavy, generally supersonic, and have warheads in the 600-1000+ lb range.  Some of these missiles are described as semi-armor piercing, whatever that means.

 

 

Shell-Missile Comparison

 

The obvious next step is to understand how shells and missiles compare as far as their ability to penetrate battleship armor.

 

Skin – A key characteristic of shells and missiles is the thickness of their ‘skins’.  A missile, even the largest, has relatively very thin skin amounting to no more than that necessary to hold the internal components in place and provide an aerodynamic shape.  In contrast, naval shells have very thick walls which both aid in penetration and serve to contain and compress the explosive chemical reaction (the blast). 

Penetration – The common, light ASMs are not generally claimed to be armor piercing and are, conceptually, simply explosives and motors contained in a very thin skin of aerodynamically shaped sheet metal.  They have no armor piercing capability whatsoever beyond their inherent kinetic energy which is woefully insufficient to penetrate significant armor.  The armor would not even need to perform its de-capping function since the missiles have no armor piercing cap.  The missile would simply explode against the outside of the armor, doing little more than scratching the paint.

 

Several decades ago, I read reports of tests by the Navy involving launches of anti-ship missiles against armor plates.  Unfortunately, at the time, I did not save the reports and have been unable to find them now.  As I recall, the missile was the Harpoon.  I do not recall the armor plate thickness or composition.  Regardless, the result was that the missile achieved no penetration and did no damage.

 

As noted, some missiles claim to be ‘semi-armor piercing’ but I’ve seen no description or definition of what that means.  Presumably, it means it might be able to penetrate some small degree of armor but, unless the missile contains true armor piercing caps equivalent to 16” battleship shells and the rest of the missile body is encased in a thick shell, the missile will have no chance of penetrating any significant degree of armor.

 

Few – I actually don’t know of any – anti-ship missiles have actual AP noses.  Battleship armor is designed to decap heavy, large caliber shells so, logically, an AP missile, if such existed, would also be decapped and prevented from penetrating.

 

I am unaware of any credible testing of anti-ship missiles against armor.  There have been Russian claims but they are unverifiable and Russian claims are almost invariably greatly exaggerated, as the Russian performance in Ukraine has demonstrated.

 

 

Discussion

 

We noted that battleship critics claim two modes of ‘destruction’ of battleships:  Let’s consider the two modes.

 

Sinking – In order to achieve a sinking, an ASM would have to penetrate multiple layers of armor to reach vital internal areas.  Even then, that would not open holes for water ingress.  Fire, of course, is always a threat to ships but with vital equipment protected, armor abounding, and extensive compartmentation, it would be very difficult to achieve a sinking. 

 

Mission Kill – As noted, topside equipment is subject to damage but nothing topside is vital.  Battleships were designed with armored sensors and had multiple redundant and backup systems so significant impairment of a battleship’s function via topside damage would be extremely difficult to achieve.  A modern version of a battleship would have its various radar, electro-optical, infrared, and electronic warfare sensors housed in armored structures as the WWII battleships did with their various radar, fire control, and optical sensors.

 

A modern version would have many isolated self-defense weapons (SeaRAM, CIWS) each of which has its own self-contained radar. A single hit could not damage much of a ship's defensive weapons. Besides, defense is what escorts are for. Citing the fact that a battleship was sunk somewhere in history does not invalidate the power and survivability of the type.

 

No ship is invulnerable but a battleship is the least vulnerable ship ever built. A battleship group with Aegis escorts would be an exceedingly difficult group to defeat.

 

Some might say that this entire discussion is pointless because we are never going to bring battleships back.  Well, that may or may not be true but there is a larger point to this and that is the role and value of armor.  Whether that armor is applied to a true battleship or to some other type of ship, this discussion reminds us that armor serves an invaluable purpose and should be part of every warship design.

 

 

 

________________________________

 

[1]NavWeaps website, “Decapping Revisited”, Nathan Okun,

http://www.navweaps.com/index_tech/tech-085.php

 

[2]NavWeaps website, “The Armor Thickness Necessary to Decap an APC Projectile”, Nathan Okun,

http://www.navweaps.com/index_tech/tech-045.php

 

[3]https://en.wikipedia.org/wiki/Iowa-class_battleship#Armor

The LAW is Confusing

Surprisingly, Marine Commandant Berger does not share his plans and thinking with me.  I know, he should but he doesn’t.  The problem is that I’m left to try to understand his plans and thinking based on the occasional public statement he or his cronies make and it seems that every statement made contradicts the one before it.

 

Now, one might think that it’s irrelevant whether I understand his plans except that he desperately wants and needs to get agreement and support from me as a taxpayer, Congress as the provider of funds, and the Navy as the builder of ships.  To date, he’s gotten support from none of those and his plans and programs are floundering.  Specifically, the Light Amphibious Warship (LAW) transport/landing ship that is key to the missile-shooting concept is in danger of being eliminated or delayed so long that the entire concept dies before it can be implemented.

 

Every new statement just confuses the issue even further.

 

For example, I was led to understand that during war with China the LAW would transport Marines to secret, hidden locations, conduct resupply, and relocate the Marines when necessary.

 

Well, the latest statements suggest this is not the case.  According to Lt. Gen. Karsten Heckl, the deputy commandant for combat development and integration, the LAW will not be anywhere near a combat zone.

 

The Marines don’t envision using this vessel during combat operations either, the general said.

 

If there are indications a conflict may break out, the combatant commander would order the light amphibious warships, or LAW, to quickly relocate Marines or resupply units, “and then it goes into hiding, it goes into bed-down somewhere. Nowhere do we envision the LAW out transiting the sea lanes in the middle of a kinetic fight.”[1]

 

Wait, what now?!  The Marines don’t envision the LAW being anywhere near combat?  Well, then, how will they locate, resupply, and relocate the Marines?  Will they call a time-out during the war to conduct those tasks while the Chinese obligingly pause and wait for the LAW to do its job and then leave the combat area?  If you recall, the concept was supposed to have been that the Marines could not be found by China but, if they were found, the LAW would nimbly and quickly relocate them to another hidden location to continue raining destruction down on the befuddled Chinese.  Now we see that the LAW won’t be anywhere near the combat zone so how will the Marines relocate, if discovered?  Will they swim to a new island, towing their missiles behind them?  I’m confused.

 

Light Amphibious Warship (LAW) - total confusion

Moving on, am I to now understand that any Marines not already in place at the start of the war won’t be able to take part in the fight because the LAW won’t be ‘transiting the sea lanes in the middle of a kinetic fight’?  And, am I to now further understand that Marines won’t be resupplied, evacuated, or relocated during the war and that once they’ve shot their small handful of missiles they won’t be receiving any reloads since the LAW will be ‘bedded down’ somewhere?

 

Another new aspect is some fantasy-level hiding scheme, according to the general,

 

Heckl said the light amphib is meant to appear like a commercial craft — to “hide in plain sight.”

 

“The [Indo-Pacific] sea lines of communication are the most traversed sea lines in the world; it would be a challenge for any power to surveil everything all the time in that area,” he said.

 

I keep hearing variations of this idiotic notion from both naval observers and uniformed Marine/Navy personnel.  There is a belief that looking like a commercial vessel is somehow going to provide immunity and ‘stealth’.  I hate to be the bearer of bad news – meaning, reality – but in a war the Chinese are going to sink everything that they can’t positively identify as friendly.  How do I know this?  Because it’s common sense and every belligerent did it in WWII.  Remember the Doolittle raid?  We didn’t hesitate to sink Japanese fishing boats during the carrier’s run in to the launch point.  That’s just elementary common sense.  If you can’t identify something as friendly, you destroy it.  Simple.  Straight forward.

 

According to Lt. Gen. David Furness, the deputy commandant for plans, policies and operations,

 

Furness said the way the light amphibious warships operate would mitigate the risk China defeats them. These ships would operate in and around the 7,000 islands of the Philippines, for example, blending in with local commercial craft and not likely to become a target for Chinese precision missiles.[1]

 

Setting aside the fantasy that the Philippines will allow us to operate on their islands and in their territorial waters in a war with China, it would be remiss to fail to note that the Philippines has a significant Chinese population and no US ship is going to operate unobserved and unreported.  Further, China is going to destroy any and all unidentified vessels without bothering to ask questions.

 

Also, in a China-US war there won’t be any commercial sea lanes.  Sea lanes are a peacetime construct.  During war, no commercial vessel is going to sail anywhere near a combat zone because they know they’ll be sunk.  The only vessel sailing in a combat zone will be known, friendly ships/warships or unknow and presumed hostile ships.  No unidentified ship, regardless of what it looks like, is going to get a free pass.  This is just unrealistic, fantasy level, wishful thinking.  I can’t excuse civilian naval observers for this type of idiotic thinking and I absolutely expect better from uniformed, professional (clearly, they aren’t) warriors.

 

But wait, there’s even more confusion.  I thought the Commandant’s vision was a concept for fighting and defeating China in a high end war.  Now I find out that war/combat is not the purpose of the Marines and their missile-shooting concept.

 

[The Marines] say their small units will be focused on deterrence, but also outfitted with the sensors and weapons to fight if necessary.[1]

 

So now I’m led to believe that these missile-shooting Marines are not combat forces but are deterrent units that will be given sensors and weapons as a last resort, to fight ‘if necessary’?

 

How will a platoon or company size unit deter China?

 

“One of the strengths of the stand-in force is to cause the adversary that moment of guessing and second-guessing their decision, and ratchet down and deescalate,” Heckl said.[1]

 

Yes, I’m sure China will halt their Taiwan invasion plans because we have a platoon of Marines hiding in the Philippines.

 

These new statements completely contradict every previous statement and understanding about this concept that I’ve had.

 

Berger wants support for his concept but every new statement just ups the level of confusion and apparent idiocy surrounding this plan. 

 

Sorry, Commandant.  Until you can elucidate a coherent plan you’ll get no support from me.

 

 

 

_______________________________

 

[1]Defense News website, “Marines, Navy near agreement on light amphibious warship features”, Megan Eckstein, 5-Oct-2022,

https://www.defensenews.com/naval/2022/10/05/marines-navy-near-agreement-on-light-amphibious-warship-features/

San Antonio Class Mast and Stealth

The San Antonio class (LPD-17) ship design included the use of a composite enclosure around the mast.  The Advanced Enclosed Mast/Sensor (AEM/S) was intended to reduce the ship’s radar signature while allowing the ship’s own outgoing and returning radar waves to pass through the enclosure unimpeded.  Thus, the enclosure was designed to be selective about which signal frequencies it reflected or passed.  The selectivity would, theoretically, enhance the ship’s sensor performance by filtering out false and spurious signals.  Additional claimed benefits included reduced sensor and mast maintenance, longer sensor life, easier sensor maintenance, and greater sensor reliability.

USS San Antonio, LPD-17 - Note enclosed masts

 

The AEM/S consists of a faceted radome that provides a cleaner exterior profile, with internal platforms on which antennas and sensors are mounted. The radome material is designed so that the antennas can transmit and receive through the material. The base of the mast is constructed from fiber reinforced composite skins encasing end-grain balsa core. The upper (radome) section consists of structural foam and fiberglass.[2]

 

The AEM/S System mast [a 93-foot-high hexagonal structure 35 feet in diameter ] is constructed of a multi-layer, frequency-selective composite material designed to allow passage of own-ship sensor frequencies with very low loss while reflecting other frequencies. The mast’s shape is designed to provide a smooth silhouette to reduce radar cross section. Signature and electro-magnetic design requirements are based on criteria associated with sensor and antenna performance, electro-magnetic interference, lighting protection electromagnetic shielding, and electrical bonding and grounding.[1]

 

The AEM/S System mast is an enclosed structure that protects radars and communication antennas from weather exposure and provides access for repairs, thus greatly reducing maintenance costs and risk of failure. The top half is divided into two radome-like compartments; the upper compartment houses the Mk 23 Target Acquisition System (TAS) antenna and the lower encloses the AN/SPS-40 air search antenna. Structural design requirements for strength and stiffness meet Fleet requirements for vibration, shock, and fatigue.[1]

 

The lower half of the AEM/S system serves to hold up the top half. The case of the lower half is balsa. An electromagnetic (EM) shield compartment that uses reflecting metallic shielding is included in a portion of the lower half of the mast to meet design requirements. The top half contains a tailored sandwich composite material made up of a foam core, with frequency selective material, as well as structural laminate skins.[4]

 

The AEM/S was initially prototyped on the USS Radford and many of the AEM/S public descriptions apply to the prototype rather than the LPD-17.  Regardless, the structures are essentially identical.

 

The AEM/S System is fabricated with an advanced composite hybrid frequency selective surface (FSS), designed to allow passage of own-ship sensor frequencies while reflecting other frequencies.

 

The upper half of the AEM/S System is designed to allow passage of own-ship sensor frequencies with very low loss while reflecting other frequencies. It is divided into two radome-like compartments; the upper compartment houses the MK 23 TAS antenna, and the lower encloses the SPS-40 air search radar antenna.[3]

 

The AEM/S has a pretty impressive list of claimed benefits, bordering on magical.  Has it delivered on the claimed benefits?  Unfortunately, there is no actual data that I’m aware of so we’re reduced to informed speculation to answer the question.

 

There have been persistent, though unconfirmed, reports of the enclosure negatively impacting own-ship sensor performance.

 

The most telling piece of circumstantial evidence is the fact that the Navy has opted not to continue using the enclosure on the next flight of LPD-17s.  Beginning with USS Fort Lauderdale, LPD-28, the mast enclosure has been discontinued.  In addition, the new Constellation class frigate will not have an enclosed mast.

 

If all the claimed benefits had actually materialized, it would have been a no-brainer to continue using the mast enclosure.  The fact that no new ships/classes have been spec’ed with the enclosure offers pretty compelling evidence that the enclosure has not been the success that was hoped and that the benefits, if any, have been insufficient to justify its continued use.

 

LPD-17 Mast Prototype on USS Radford

 

 

USS Fort Lauderdale - Note the conventional, open mast

 

Consider the logic of the reflectivity/transmission characteristics.  The claim is that the enclosure reflects incoming enemy radar waves while allowing the ship’s own outgoing and return sensor signals to pass unimpeded.  Does it seem plausible that this can actually occur?  The enemy, like us, uses a multitude of radar and sensor frequencies, often the same ones we do, so how can an enclosure reflect enemy radar waves while allowing the exact same frequency waves of the ship’s sensors to pass unimpeded?  Logic would suggest it can’t. 

 

If the enemy only used one frequency and we used a different one than, yes, it might be possible to construct such a selective enclosure.  However, in these days of multi-frequency and/or frequency hopping radars, trying to design a selective friendly/unfriendly enclosure would seem impossible.  Indeed, the persistent reports suggest that the enclosure is not performing as claimed and that, in particular, the ship’s own signals are being impeded.

 

It would appear that the AEM/S is a failure which raises the question, why didn’t the prototyping on the Radford reveal the problems and prevent the enclosure from being used on the LPD-17 class?  I suspect this may have been a case of unrealistic testing that was designed not to find faults but to validate a decision already made.

 

 

 

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[1]https://man.fas.org/dod-101/sys/ship/lpd-17.htm

 

[2]https://en.wikipedia.org/wiki/Advanced_Enclosed_Mast/Sensor

 

[3]https://www.globalsecurity.org/military/systems/ship/aems.htm

 

[4]https://cimsec.org/22119-2/

The LVT Family

WWII saw the birth of the Landing Vehicle Tracked (LVT) amphibious assault vehicle, known variously as the "amtrak", "amtrac", "alligator", or "buffalo", among other nicknames.  The vehicle was the answer to the Marine’s need for a protected transport capable of traversing surf and coral.  The development of an armored version with a 75 mm howitzer provided anti-infantry and anti-fortification firepower available in the initial assault wave.  Later, a flamethrower capability was added. 

 

The personnel carrying LVT was the forerunner to today’s standard Assault Amphibious Vehicle (AAV).  Indeed, the AAV was initially designated the Landing Vehicle, Tracked, Personnel-7 (LVTP-7).

 

We see, then, that during WWII, the LVT variants included transport, flamethrower, and armored “tank” versions.  These developments were critical to the Pacific war island assaults and were impressive enough in their own right.  However, after the Korean War, the LVT underwent yet another round of development resulting in an entire family of functional variants.

 

The base vehicle for the subsequent LVT family was the 35 ton LVTP-5.  The variants, designed by Borg-Warner Corp., included (1),

 

LVTP-5 – personnel carrier rated for up to 35 troops (though not in practice) 

 

LVTP-5

LVTH-6 – armored amphibian with fully stabilized armored turret housing a 105 mm howitzer with storage for 151 rounds plus an additional 150 rounds in the cargo hold, a 0.30 cal co-axial machine gun, and a 0.50 cal anti-aircraft machine gun

LVTH-6

LVTC-5 – command vehicle with extensive communications suite for battalion or regimental command;  could send and receive on 7 channels and monitor 4;  space for seating and map boards

 

LVTAA-1 – anti-aircraft vehicle fitted with the M42 Duster turret housing twin 40 mm Bofors;  Note: It appears that the LVTAA-1 never entered production after prototype testing.

 

LVTR-1 – recovery vehicle with two winches, each capable of pulling 45,000 pounds, a welding rig, crane and other maintenance equipment (2)

LVTR-1

LVTE-1 – combat engineer and breaching vehicle with an angled blade plow for mine clearing that could clear a 12 ft wide lane to a depth of 16 inches; also included a top mounted, rocket-propelled demolition line charge launcher for mine and obstacle clearance

LVTE-1

The really noteworthy aspect of this bit of amphibious vehicle history is that we still need the same functions today!  The absolutely astounding aspect of this bit of amphibious vehicle history is that most of the required functions are still unmet, today!  

AAV

 It is also interesting to note how little the base vehicle has changed.  If we could simply, magically, transport these vehicles to our time, we’d find them quite welcome and useful.  That illustrates how little improvement has occurred in amphibious assault – arguably, we have regressed since we now lack any kind of amphibious heavy firepower which we commonly had in WWII !

 

The AAV/ACV (ACV – Amphibious Combat Vehicle) that is currently being produced has barely changed, functionally, from its historical predecessors and lacks the various variants that are required for a fully functional amphibious capability.  The Marines have discussed adding ACV command and 30 mm gun variants but nothing has happened as yet and budget constraints suggest that few, if any, variants will be produced.

 

This raises the larger question, are the Marines actually serious about amphibious assault?  The statements, doctrine, acquisitions, and budget allocation present a very mixed bag of answers.

 

Statements by various Marine leadership claim that amphibious assault remains a core capability, that a line of AAVs assaulting the beach will never be seen again, that traditional assaults are a thing of the past, and that the AAV/ACV is vital for the Marine mission.  An astounding bit of mixed messaging, for sure!

 

Doctrinally, the Marines/Navy call for a standoff distance of 25-50+ miles for an opposed assault.  This suggests that the Marines are not serious about amphibious assault since they have no landing craft capable of conducting effective 25-50+ mile transits.

 

Marine acquisitions and budgets are heavily focused on the aviation – and now missile – side of things.  The lack of importance attached to assault is evidenced by the decades spent meandering around the AAV replacement issue (recall the failed EFV?).  Even now, with new ACVs being procured, the utter lack of amphibious firepower and anti-air capability is startling and sends the message that amphibious assault is not a priority and may not even be feasible (if so, why are the Marines even procuring ACVs?).

 

One final bit of evidence about the degree of likelihood and seriousness with which the Marines view amphibious assault is that the Marines have never conducted an exercise using their own doctrine of assaulting from 25-50+ miles – because they know it can’t be done with the capabilities they currently have.  Further, there is no serious investigation of 25-50+ mile connectors being conducted.  Recall any photo you’ve ever seen of Marine amphibious exercises.  The AAVs are pictured coming ashore in neat rows with a giant amphibious ship parked just offshore so that the AAVs had a very short ride to the beach (barely getting wet in the process!).  Great photo op but worthless training.

 

Amphibious Assault Exercise - note the proximity of the host ship

If the Marines are serious about amphibious assault – and that’s a huge ‘if’ – they desperately need a complete family of vehicles identical in function to the post-WWII LVT family.  If the Marines are not serious about amphibious assault, as the preponderance of evidence suggests, then they need to stop wasting money on ACVs which will never be used.

 

 

 

 

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(1)”Marines Under Armor”, Kenneth W. Estes, Naval Institute Press, 2000

 

(2)http://www.benning.army.mil/armor/eARMOR/content/issues/1993/MAR_APR/ArmorMarchApril1993web.pdf , p. 13