UUM-44 SUBROC With Mk-44/46?

[TomS]

I didn't immediately think of CAPTOR -- more the Chinese EM-52 -- but it totally is, just with a submarine rather than surface ship target set.

This is far enough off topic for SUBROC that we should probably make a separate thread, possibly over in Military.

 

[Scott Kenny]

That's a shortcoming, to be sure. Although a Mark 44 couldn't do that, either, which is contemporary technology. If you wanted a medium-weight air-delivered torpedo, you'd doubtless make a new one of broadly comparable size. Interestingly, Russian/Soviet air-delivered torpedoes tend to be in the Mark 37 size and weight class.

Modern subs are getting to the performance level that I'm thinking that the 12.75" LWT (Mk46/50/54) are just not capable enough, specifically too short a run time.

So I'm expecting the US to start looking at Mk37 sized torpedoes for their primary ASW weapon. Mk37s are almost 1500lbs, however, which is right at triple the weight of a Mk46 and not quite double the weight of a Mk50.

But even if we go simple and assume that the USN's next helicopter is going to be an H60 with a pair of T901s, it should be able to carry a pair of Mk37 class torpedoes and the sensor gear. And then you replace the Mk32 triple tube launchers with a single 21" tube like on a lot of the FRAM DDs.

 

[TLAM_Strike]

So I'm expecting the US to start looking at Mk37 sized torpedoes for their primary ASW weapon. ... And then you replace the Mk32 triple tube launchers with a single 21" tube like on a lot of the FRAM DDs.

They looked at that back in the day, I believe Admiral Zumwalt killed the idea. The Knox-class frigates (and others) were to have stern mounted 21" torpedo tubes for wire guided Mk48s. The first photo I attached is of USS Talbot FFG-4 testing Mk48 from her stern tubes (operationally these used Mk37, but were removed from most ships after a short while). They are covered by a hatch when not in use. The second photo shows a similar hatch on the stern of Truxtun DLGN/CGN-35, not sure if Truxtun actually had them installed or not.

After the tubes were removed the space was used for things like towed sonar arrays or decoys.

The first few Spanish licensed built Knox-class frigates kept the stern tubes for a while (till the 80s or early 90s) but only used Mk37 from them.

The Euros were really fond of these setups too, see photo from Saudi frigate which is a French design. The Italian Audace-class and some German fast attack craft used a similar design.

 

[Scott Kenny]

They looked at that back in the day, I believe Admiral Zumwalt killed the idea. The Knox-class frigates (and others) were to have stern mounted 21" torpedo tubes for wire guided Mk48s. The first photo I attached is of USS Talbot FFG-4 testing Mk48 from her stern tubes (operationally these used Mk37, but were removed from most ships after a short while). They are covered by a hatch when not in use. The second photo shows a similar hatch on the stern of Truxtun DLGN/CGN-35, not sure if Truxtun actually had them installed or not.

After the tubes were removed the space was used for things like towed sonar arrays or decoys.

The first few Spanish licensed built Knox-class frigates kept the stern tubes for a while (till the 80s or early 90s) but only used Mk37 from them.

The Euros were really fond of these setups too, see photo from Saudi frigate which is a French design. The Italian Audace-class and some German fast attack craft used a similar design.

IIRC it was to save some $$$ from developing the surface Mk48 variant.

But using something like the "Cheap Heavyweight Torpedo" if you can keep the weight down to about that of a Mk37 is viable. Modern helicopters can carry all the ASW gear and a 1500lb torpedo or two.

 

[TLAM_Strike]

There is a tread now to bigger shipboard ASW helicopters with Merlin and Cyclone, which I imagine could carry such a torpedo. The US does seem interested in a cheap HWT with RAPTOR; I don't know if cheap HWT and ASW really go together, because the most difficult target calls for the most expensive weapon.

With the Constellation-class frigates the Navy seems to think deck mounted torpedo tubes are a thing of the past I think we might see something other than a 21" and 12.75" form factor with a weapon designed around fitting a new ASROC in a VLS cell that would be adapted for use by aircraft. At least the torpedo warhead part of it probably with a glide bomb kit slapped on for P-8 compatibility.

Who knows with all that space on some helicopters maybe we'll see something wire-guided like some of the systems they use for mine countermeasures. Go cheap by keeping part of the system attached to the helo?

 

[Scott Kenny]

There is a tread now to bigger shipboard ASW helicopters with Merlin and Cyclone, which I imagine could carry such a torpedo. The US does seem interested in a cheap HWT with RAPTOR; I don't know if cheap HWT and ASW really go together, because the most difficult target calls for the most expensive weapon.

A sub that's up shallow hunting surface ships is relatively limited in performance. Can't go too fast because there's not enough water pressure to prevent cavitating and telling the whole world where you are. May not be able to go deep quickly.

If you can drop a heavyweight torpedo close to them, it will be very difficult for the sub to escape.

Lightweight torpedoes are more likely to pop the shaft seals IF the sub can't outrun them, which is a mission kill at least.

Who knows with all that space on some helicopters maybe we'll see something wire-guided like some of the systems they use for mine countermeasures. Go cheap by keeping part of the system attached to the helo?

They may have to. I somehow doubt that either the engine or the warhead is particularly expensive...

 

[TLAM_Strike]

They may have to. I somehow doubt that either the engine or the warhead is particularly expensive...

I dug around some documents and a Mk50 was between $750K-$1M in early 2000s money. The Lightweight Hybrid Torpedo program to stick the Mk50 guidance system on the Mk46 torpedo cost $280K a unit (keep in mind kits for an existing torpedo). So, subtracting the cost of the guidance system, the torpedo body, warhead, engine, "fuel tank", and propulsor are about half a million in early 2000s money.

Here is a fun little graph, its not cost per unit but itemized development cost for all torpedoes over time. Guidance and propulsion (I'd factor silencing as part of population) are the two biggest costs in developing the weapon. The warhead is rather a bargain since we know how to make things to boom rather well; this would probably drop off a bit on a newer torpedo since we're not dealing with double hulled Russian beasts anymore.

 

[TinWing]

They looked at that back in the day, I believe Admiral Zumwalt killed the idea. The Knox-class frigates (and others) were to have stern mounted 21" torpedo tubes for wire guided Mk48s. The first photo I attached is of USS Talbot FFG-4 testing Mk48 from her stern tubes (operationally these used Mk37, but were removed from most ships after a short while). They are covered by a hatch when not in use. The second photo shows a similar hatch on the stern of Truxtun DLGN/CGN-35, not sure if Truxtun actually had them installed or not.

After the tubes were removed the space was used for things like towed sonar arrays or decoys.

The first few Spanish licensed built Knox-class frigates kept the stern tubes for a while (till the 80s or early 90s) but only used Mk37 from them.

The Euros were really fond of these setups too, see photo from Saudi frigate which is a French design. The Italian Audace-class and some German fast attack craft used a similar design.

More recently, the UAE supposed procured German torpedos for stern tubes on little 58 meter support ships. https://ukdefencejournal.org.uk/uae-may-be-able-to-target-iranian-submarines-at-base/
Apparently, the German DM2A4 can run near the surface and raise a tiny GPS aerial for midcourse guidance. Attacking Iranian subs in harbor with torpedoes fired from UAE territorial waters would be a clever trick. Recent events in the Black Sea might prove the efficacy of the concept, although the weapons in question were supposedly crude and slow UUVs.

I do have to wonder if the DM2A4 is the inspiration for the USN’s proposed “cheap” HWT? Battery technology has come a long way and offers a viable alternative to OTTO II at a fraction of the price. I’m not suggesting the USN has surface launched HWT torpedos in mind. However, the modular nature of the DM2A4 stackable batteries could make half length HWTs a viable option, either for USV surface launch, external tubes on UUVs, air launch or double loading tubes like the Swedes do with their 400mm torpedoes.

Of course, with the prospect of small anti-torpedo towed arrays in addition to towed torpedodecoys, large ASW active towed arrays, and the modern obsession with ramp launched RHIBs, stern real estate on ASW escorts is going to be at a premium. A pair of HWT tubes doesn’t take up all that much space, although reloading facilities would. There was quite a torpedo room designed into the stern of the old Knox class.

 

[Scott Kenny]

More recently, the UAE supposed procured German torpedos for stern tubes on little 58 meter support ships. https://ukdefencejournal.org.uk/uae-may-be-able-to-target-iranian-submarines-at-base/
Apparently, the German DM2A4 can run near the surface and raise a tiny GPS aerial for midcourse guidance. Attacking Iranian subs in harbor with torpedoes fired from UAE territorial waters would be a clever trick. Recent events in the Black Sea might prove the efficacy of the concept, although the weapons in question were supposedly crude and slow UUVs.

I do have to wonder if the DM2A4 is the inspiration for the USN’s proposed “cheap” HWT? Battery technology has come a long way and offers a viable alternative to OTTO II at a fraction of the price. I’m not suggesting the USN has surface launched HWT torpedos in mind. However, the modular nature of the DM2A4 stackable batteries could make half length HWTs a viable option, either for USV surface launch, external tubes on UUVs, air launch or double loading tubes like the Swedes do with their 400mm torpedoes.

Wouldn't surprise me if it was the inspiration. Though the idea of anything German made as "cheap" makes the mind boggle.

Of course, with the prospect of small anti-torpedo towed arrays in addition to towed torpedodecoys, large ASW active towed arrays, and the modern obsession with ramp launched RHIBs, stern real estate on ASW escorts is going to be at a premium. A pair of HWT tubes doesn’t take up all that much space, although reloading facilities would. There was quite a torpedo room designed into the stern of the old Knox class.

Yeah, if you can keep the cheap HWT down to ~1500lbs it's easier. I know I was basically assuming a single 21" tube per side in place of the triple LWT tubes. And then just throw the cheap HWT over the side like WW2 days.

 

[TLAM_Strike]

However, the modular nature of the DM2A4 stackable batteries could make half length HWTs a viable option, either for USV surface launch, external tubes on UUVs, air launch or double loading tubes like the Swedes do with their 400mm torpedoes.

If they could make it a 21' "shorty" you can use deck mount like the French did with theirs where its about the size of an SVTT (little bigger) and you can carry reloads on deck (structure to the right of the tubes in the 2nd pic).

Didn't know the Swedes did two 400mm torpedoes in a tube. You have more info on that? Is it two stacked one behind the other is it two sub-caliber weapons side by side (I've seen photos of the MOSS stowed like that).

 

[TinWing]

Didn't know the Swedes did two 400mm torpedoes in a tube. You have more info on that? Is it two stacked one behind the other is it two sub-caliber weapons side by side (I've seen photos of the MOSS stowed like that).

Apparently they can load them them in a tube in tandem. Two shots. HI Sutton wrote about it for Forbes