Showing posts with label Mk48 Torpedo. Show all posts
Showing posts with label Mk48 Torpedo. Show all posts

Monday, April 6, 2026

Why Do We Have Lightweight Torpedoes?

During the Cold War, the US Navy concluded that lightweight torpedoes were largely ineffective against Soviet submarines, in terms of achieving a kill.  Even heavyweight torpedoes were questionable and thought to require multiple hits to kill.  Lightweight torpedoes were considered more of an annoyance to Soviet subs than a lethal threat.
 
Lightweight torpedoes are a lethal threat only to small, lighter built diesel subs.
 
Lightweight torpedoes are not a ship-sinking threat to anything much bigger than a patrol boat and are not capable of sinking surface ships, either merchant or naval.
 
That being the case, why is the Mk54 lightweight torpedo so ubiquitous throughout the surface Navy?  Wouldn’t it make more sense for ships to mount heavyweight torpedoes?
 
Here’s a brief comparison of the Mk48 heavyweight and Mk54 lightweight torpedo characteristics.  Characteristics vary, of course, depending on the exact model but these are representative.  Note the lightweight torpedo’s warhead weight and range deficiencies compared to the heavyweight torpedo.




The Mk48 heavyweight torpedo can do anything the lightweight can (which isn’t much) plus it is capable of : 
  • Sinking merchant ships
  • Sinking submarines
  • Sinking surface ships
  • Destroying maritime structures (oil platforms and such)
 
There have been reports over the years that the Mk48 has problems in shallow water.  The lightweight torpedo was intended, in part, to be the answer to shallow water issues but has had its own reported problems.  The last DOT&E annual report that I can find for the Mk54 assessed it as operationally ineffective (2014 report) and not operationally suitable (2023 report).
 
All of this leads me to ask, why isn’t the Mk48 standard on surface ships?

Monday, June 10, 2024

Deadly Fish

Gotta get closer to shore, the Captain thought.  They were already dangerously, recklessly close with only a few feet of water under the keel but safety – and surprise – lay to the starboard, landward side of the ship, not the open ocean to port even though every sailor’s instinct told him to veer off and make for open water. 
 
A few whispered commands and more than a few discrete, disbelieving looks from the immediate crew and the ship inched closer to shore.
 
If any ship could carry out this mission, the Captain knew, it was this one.  The ship was a Fletcher II class destroyer – a true destroyer, not some unholy, underarmed, unarmored, cruiser size ship that was designated a destroyer to keep Congress from asking inconvenient questions.  This was a ship built to fight and kill.  The ship was designed with maximum radar, IR, and acoustic stealth to be as nearly invisible as was possible.  It mounted four 5” guns, dozens of CIWS and SeaRAM mounts, and a main battery of 10x 650 mm torpedoes in two quintuple, centerline, rapid reload launchers, one midships and one nearer the stern to provide separation in the event of battle damage.
 
Right now, the ship, and her five squadron mates were on their way to knock out the southern Chinese invasion fleet that, along with a middle and northern fleet, had been attacking Taiwan at three separate sites for the last five weeks.  The Taiwan forces had managed to absorb the initial assaults at great cost but were losing as the Chinese continued to pour reserve forces and supplies into the assaults.  Something had to give.
 
The preferred method of attack against the invasion fleet had been the anti-ship cruise missile but US stocks (and Chinese stocks!) had been quickly depleted in the first three weeks and had proven largely ineffective against the Chinese version of Aegis.  The US had believed in the effectiveness of their own Aegis system so it should have come as no surprise to US planners that the Chinese version (copied and improved from Aegis) would also be effective.  Yes, there had been several Chinese ships of various types sunk or knocked out of the fight but the Chinese pre-war numerical advantage and close proximity to the assault had allowed them to absorb the hits with almost no operational impact.
 
The US had targeted the amphibious and supply ships which, in hindsight, had been a mistake as it exposed the attacking cruise missiles to the full depth of the escort’s protective anti-air defensive layer.  Relatively few of the thousands of missiles launched over the weeks had gotten through.  The Navy’s Tomahawk Block V, while lauded by Navy leadership pre-war, was still, essentially, 1980’s technology with a few added enhancements mostly related to networking and remote communications which had no actual combat value.  It was, for all practical purposes, the 1980’s Tomahawk Anti-Ship Missile (TASM).  While the range was impressive at 1000 miles, the missile lacked the supersonic speed, terminal maneuverability, and on-board countermeasures to successfully penetrate the Chinese Aegis defenses.  Range without lethality was pointless, as the Navy had found out the hard way.
 
The Navy’s air-launched Long Range Anti-Ship Missile (LRASM) had had greater success but the Navy had unwisely cancelled production in anticipation of a Next Generation LRASM (NG-LRASM) and, thus, inventories were very small and the missiles were depleted in the first two weeks.
 
Thus, it was that the Fletcher II class squadron found itself skimming the southern shore of Taiwan, literally hugging the coast to blend their already minimal radar signatures with the returns from the land as they proceeded single file at 30+ knots with just 50 m bow to stern separation between ships.  This was insane sailing by any peacetime standard but was now the preferred tactic for this mission.  Only by getting lost in the land’s radar and acoustic clutter could the ships hope to survive long enough to reach their launch point.
 
The destroyers had broken off from escorting a resupply convoy as it pulled into Hualien during the early evening as darkness was descending.  Hualien was a major port on the central, east coast which was protected by mountains and had become a natural convoy destination.  It was 170 miles from Hualien to the southern tip of Taiwan – around five and a half hours sailing at the destroyer’s best speed.  The Chinese had seen convoys come (some badly battered, some largely untouched) and go from Hualien repeatedly and one more convoy went unremarked by Chinese infiltrators watching from the heights.  The appearance or disappearance of a handful of escort destroyers didn’t attract the attention of the Chinese army infiltrators who didn’t really know or care about naval matters.  The destroyers were just ships going about their convoy escort duties as they had done dozens of times before. 
 
Map of Taiwan
 

Now, the destroyer squadron rounded the southern tip of the island, just seventy or so miles to the Chinese invasion fleet.  Another five miles and the squadron reached the launch point.  Every additional mile from this point on significantly increased the risk of detection.
 
One after another, the destroyers pivoted away from the shore to unmask their centerline torpedo launchers and began the launch, rapid reload, launch cycle.  Each ship carried 40 torpedoes and the squadron launched a total of 240 torpedoes in under ten minutes before reversing course to head back the way they came, their mission complete.
 
Southern Tip of Taiwan


As the wave of torpedoes approached the invasion fleet at their 30 kt cruising speed, they stayed near the shore where the surf noise helped mask their motor noise.  At around five miles, however, the torpedoes spread out along a ten mile front perpendicular to the shore.  This set up a ten mile wide sweep through the invasion fleet’s location.
 
At this point, the outlying fleet escorts began to pick up the acoustic signatures of the approaching torpedoes and, after a few more minutes of indecisiveness, confirmed the detection of the torpedoes and sounded the alarm.  The ships that were moving began to turn away and scatter to the north while those that were stopped or anchored began, frantically, to get underway.  Ironically, the initial reaction of the outer ships, which was to turn away from the threat, wound up bringing them closer to the main amphibious fleet and had the effect of concentrating the targets for the torpedoes.
 
With so little warning, there was no hope of escape as the torpedoes accelerated to their terminal attack speed of 60 kts.  The torpedoes began sensing individual targets and their simplistic programming resulted in them locking onto the nearest valid target, often multiple torpedoes per target.  The torpedo designers had purposely omitted any attempt at sophisticated target discrimination, acoustic imaging, networked smart allocation of targets, or any other worthless action that contributed nothing but cost to the torpedo.  These torpedoes were ‘dumb’.  They would go after the first target they saw that met some basic criteria.  This meant inefficient allocation of weapons but the designers realized that the solution to that was numbers.  If you could put enough weapons in the water, it didn’t matter how inefficient they were.  These torpedoes were the equivalent of area bombardment.  They would attack any target and amongst a Chinese invasion fleet, any target was a good target.
 
The Chinese ships frantically fled, twisting and turning to avoid the incoming torpedoes.  There were a few collisions and many near misses but, ultimately, it did no good.  A ship might evade one torpedo but the seeming endless wave of torpedoes ensured that another torpedo would lock on.  The first torpedoes began impacting and explosions and fires began dotting the sea.  The wave of torpedoes continued on.  Inevitably, by pure chance, some ships escaped being targeted and survived but the southern flank of the invasion fleet was devastated and disrupted.
 
The wave front of torpedoes continued on, passing through the escorts and impacting the largely motionless amphibious ships.  Ship after ship took hits, ripping the guts out of the invasion.  By the time the torpedoes passed through the center of the fleet and began approaching the northern escorts, there were few torpedoes left but even those few managed to completely disrupt the escorts, causing them to flee further north.
 
With the Chinese invasion fleet broken and the carefully networked Aegis-like air defense completely disrupted, a carefully timed B-2/21 bomber force, heavily supported by electronic warfare aircraft and led by an F-22 fighter sweep, hit the surviving ships of the invasion fleet with a barrage of various close range air dropped weapons.  This kind of close attack couldn’t have succeeded if the escort force was still intact, networked, and integrated.  The destroyers, however, had seen to that threat.  As the bombers and fighters pulled off their attack and headed home, the Chinese southern invasion fleet had, for all practical purposes, ceased to exist, providing some badly needed relief to the Taiwan defenders and allowing the defensive forces to concentrate on the middle and northern invasion sites.
 
 
 
 
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The Torpedo

Don’t believe the torpedo described in the story could exist?  Consider these range specifications for real torpedoes.
 
 
US Mk48 Torpedo
Range: 
38 km (24 mi; 21 nmi) at 55 kts
50 km (31 mi; 27 nmi) at 40 kts
 
Type 65 Soviet 650 mm Torpedo
Range:
50 km (31 miles) at 50 kts
100 km (62 miles) at 30 kts
 
Is it that big a leap to believe the torpedo described in this story could exist?
 
Story Torpedo
Range: 
137 km (85 miles; 74 nmi) at 30 kts with 60 kt terminal attack speed
 

 
Story Aspects
 
This story demonstrates, among several other things, the value of a very basic weapon.  The imagined torpedoes have been designed with none of the wire guidance, multi-mode seeker, acoustic imaging, etc. that drives up cost, consumes internal volume, increases production complexity which decreases production rates, requires complex software, and adds little combat capability improvements.  Thus, the internal volume savings can be devoted to additional fuel and/or a larger warhead.
 
Simpler, easier to produce, cheaper, and just as lethal – what’s not to like?

  
The story also demonstrates the value of an optimized, specialized weapon system, the destroyer, whose sole primary purpose was anti-surface/torpedo.  A multi-function ship with just a few torpedoes could never hope to achieve the kind of wholesale, efficient destruction described in this story.  The entire navy wouldn’t be composed of these ships, of course.  It would just be one or two squadrons worth.  The rest of the fleet would be a mix of various other ships, each with their own specialization.  This gives the operation planner a menu of specialized ships to choose from instead of being forced to use just one ship type which isn’t optimized for any one function (hi, Burke!).
 
 
Yet another aspect of the story is that it Illustrates the profligate expenditure of weapons (many readers will be shocked by the number of torpedoes used, having completely forgotten what real missions require in a true war) which is  characteristic of every real war in history and totally absent from every pre-war plan in history.
 
 
Missions
 
Additional mission examples for a torpedo destroyer might include:
 
  • Sinking merchant ships in a blockade scenario, something that the current Navy surface ships would have a very difficult time doing.
  • Launching specialized recon torpedoes (USV) for recon of harbors, shorelines, chokepoint passages, etc.
  • Land attack using torpedoes with suitable fuzing against docks, dry docks, shoreline facilities, etc.
  • Destruction of causeways being used to unload ships
  • Anti-ship attack from over the horizon using with the aid of spotter UAVs
  • Convoy escort
 
 
Fun Facts:
 
From Wiki:
  • The torpedo inventory of the U.S. Navy in 2001 was 1,046 Mk-48 torpedoes.
  • In 2017 Lockheed's production was approximately 50 per year.
  • Mk48 production ended in 1996.  Production restarted in 2016 with initial deliveries in 2022, as best I can tell.
 
Disclaimer:  As always (and always ignored!), this is not intended to be a true combat simulation.  It is intended to illustrate some concepts in a more readable - and hopefully enjoyable - format.

Monday, August 31, 2020

Torpedo Development

The US Navy’s torpedo, in its current form, has been around since at least the early 1900s.  In fact, aside from improved guidance, the basic torpedo is almost unchanged.  Over the ensuing 100+ years, huge strides have been made in all kinds of weapons but, for some reason, the torpedo has languished.  Yes, there have been improvements in engine efficiency and sensors/guidance but the fundamental torpedo has not changed.  That seems odd, doesn’t it?  As with so many vital combat systems (ASW, naval gun support, armor, etc.), the Navy has shown little interest in the torpedo and made little effort to develop it. 

Well, it’s a torpedo, you say.  What else can be done with it?  It is what it is.  If that seems like a reasonable summation to you then congratulations, you’re a prime candidate for admiral in the US Navy.  For the rest of us, let’s take a look at what developments might be possible for the torpedo.

The Navy’s current heavyweight torpedo is the Mk48.  Here’s a few features and points of interest:
  • Mk48 has been operational since 1972.
  • Mk48 Mod 5 ADCAP (Advanced Capability) IOC 1987
  • Mk48 Mod 7 CBASS (Common Broadband Advanced Sonar System) IOC 2006


Mk48 Torpedo Features
Size
19 ft long, 21 in diameter
Warhead
650 lb, high explosive
Cost
$3.8M for current version
Range
31 miles at 40 kts



So, what’s wrong with that?  It seems like a good torpedo, right?  Wrong!  Let’s see what other countries have in the way of torpedoes.

Russia leads the way in torpedo advances and development, dating back to the Cold War efforts of the Soviet Union.  The Soviet Union/Russia has always relied on their submarine fleet to compensate for their lack of surface navy capabilities compared to the West/US so it is not surprising that they lead the world in torpedo development.

Germany and China also have some noteworthy torpedoes.

The UK’s Spearfish torpedo, while fairly pedestrian, is reported by NavWeaps as having an 80kt max speed version which would be impressive for a conventionally powered (non-supercavitating) torpedo.(3)

The table below lists some of the features and examples of torpedo developments that the US lacks.


Foreign Torpedoes
Supercavitation
German firm in early 2000’s developed a 250 mph torpedo (1);  Russian VA-111 Shkval 230 mph (2);  SKorea has a supercavitating torpedo (see, “Korean Supercavitating Torpedo”)
High explosive weight
Russian 650 mm 65-76 with 992 lb warhead;  Russian 65-76 DST92 with 1225 lb warhead;
Very long range / very high speed
Russian 650 mm 65-76a with 62 mile max range and 50 kts max speed;  UK Spearfish with 80 kt max speed (3)
Wake homing
Russian 650 mm 65-76;  Chinese 533 mm Yu-6



The table demonstrates that existing technology is significantly beyond that of the US Mk48 torpedo.  Given our dependence on submarines to carry a lot of the naval combat responsibilities during war, this is disappointing.  As with mine countermeasures, ASW, naval gun support, ship armor, and so many other areas of naval combat, the Navy steadfastly refuses to recognize and support the development of key areas and torpedoes are yet another example.  Because torpedoes don’t garner giant sums of money in the budget, the Navy has little interest in torpedo development.  You would think the US Navy would have forever learned an institutional lesson about torpedoes from its WWII fiasco … but obviously not.

Clearly, the prize for the best torpedo in the world goes to the Russian 65-76 DST92, wake homing, 1225 lb warhead, 62 mile range, and up to 50 kt speed.  The US Navy Mk48 isn’t even in the running!

Before we move on from current, state of the art foreign torpedoes, let’s recall a torpedo from the past – the Japanese Type 93 Long Lance.  The Long Lance was a 24 inch diameter torpedo with a 1080 lb warhead and a range of 12 miles at 49 kts (22 miles at 36 kts).  This was a ship killer!  For more on WWII torpedoes, see “Torpedoes –Then and Now”.

Moving beyond the current state of the art – and the past! - , what future torpedo developments should we be looking at?  Here’s some possibilities:

Stealth – just as aircraft stealth took a giant leap forward with proper shaping and coatings, so too, might torpedoes benefit from shaping and coatings designed to reduce the acoustic signature and reflectivity of sonar sound waves;  torpedo noise reduction (propulsion, mainly) is certainly possible though possibly at the expense of speed

Supercavitation – the concept has already been demonstrated and just needs to be refined to allow more effective steering and target sensing

Multiple Warheads - a torpedo that can separate into multiple warheads like a MIRV or cluster bomb might prove useful in evading torpedo defenses and maximizing damage

Tagging – torpedoes that ‘tag’ a target rather then explode might prove useful in tracking ship movements and finding larger task forces;  magnetic or chemically attaching ‘warheads’ would seem possible

New Explosives – Significant advances have been made in air/land explosives and that leads one to speculate that similar advances ought to be possible for torpedoes;  for example, the equivalent to fuel-air explosives, using chemical-water reactions are theoretically possible given the existence of elements that react violently with water

Wake Homing – again, this technology exists and just needs to be adapted to US torpedoes and, possibly, enhanced

Chemical Trace Homing – small quantities of chemicals given off by the target ship are ‘sniffed’ in the water and tracked; this technology has been demonstrated in laboratories and rumor suggests is being tested in Russian submarines;  the challenge is to miniaturize it and adapt it to torpedoes

Terminal Evasive Maneuvers – enemy countries are working on active anti-torpedo interceptors so, just like anti-ship cruise missiles are capable of performing terminal evasive maneuvers, there is no reason why a torpedo shouldn’t be able to do the same

Littoral – the Navy found out that the neither the Mk48 nor the Mk54 lightweight torpedo were effective in shallow water ASW scenarios;  we need to develop a shallow water torpedo

Networking – cruise missiles are capable of networking, in flight, and performing self-designation of targets;  similarly, a torpedo salvo ought to be able to network and self-determine target allocation

Containerized Storage and Launching – just as VLS missiles are now containerized to reduce maintenance and protect the missiles from the environment, so too, should torpedoes be containerized for storage and launch



There you have some examples of the kinds of torpedo developments the Navy should be looking at.  I’m sure there are many other possibilities, as well.  If we’re going to depend on our submarines to carry the load in future naval combat then we simply must provide our subs with the very best torpedoes in the world.  At the moment, we are not doing that and, in fact, we are running a distant second to Russia.  The Navy’s failure to aggressively develop new torpedo capabilities hamstrings our submarine’s combat performance.  This has to change.  We cannot afford a repeat of the WWII torpedo fiasco.  We need to do the hard work and develop new torpedoes … now.



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