UUM-44 SUBROC With Mk-44/46?

[Deleted member 29851]

I occasionally here of a proposal to arm the UUM-44 SUBROC with a lightweight torpedo (probably the Mk-44 or Mk-46) instead of a nuclear depth charge. Is there any truth to this?

*I have heard of the Sea Lance and how it would replace the UUM-44, and carry a Mk-50. This is not what I’m looking for.

 

[Sferrin]

Never heard that. (Doesn't mean it isn't true.) ASROC could have either the torpedo or nuke though. Now it's torpedo only unfortunately.

 

[isayyo2]

Maybe somewhere in the China Lake or Dahlgren archive?

 

[TomS]

Friedman (US Naval Weapons) mentions a requirement for a torpedo payload early in SUBROC's development but doesn't give any details.

 

[NMaude]

I'd read somewhere years ago that the SUBROC was also going to have a torpedo (Probably a Mk-46 variant) but it was dropped early so it only carried the W-55 two-stage thermonuclear depth-charge. I'm not certain but did the SUBROC also have secondary land-attack role?

 

[Hood]

Presumably Mk 46 would have been considered pretty marginal against deep targets, given the need to drop by parachute, descend to depth and start a search pattern it would have been a slower engagement than dropping a W-55 and blasting an entire area.

I wonder if the rationale for SUBROC was primarily to engage Soviet SSBNs at long range? No need to close to torpedo range and risk the boomer detecting the US SSN and getting off a missile or two before being destroyed by torpedo. With a nuclear W-55 its quick and violent and you have a greater chance of destruction at depth. Even if they hear the splashdown of the depth charge there would be little time to react before a large area of sea becomes a pressure cooker.

 

[NMaude]

Didn't the W-55 have a 250KT yield? If so that would give it a massive underwater blast-radius.

 

[NMaude]

I wonder if a version of the Mk-48 torpedo could've been developed as a payload for the SUBROC?

 

[Sferrin]

I wonder if a version of the Mk-48 torpedo could've been developed as a payload for the SUBROC?

The Mk48 is bigger than Subroc.

 

[fishpond]

When the RN considered buying SUBROC, it wanted a non-nuclear payload, and there were formal studies of how well that combination would work. I suspect that the nuclear warhead had a destruction radius similar to the effective homing radius of a homing torpedo. At ;east some of these papers survive in the PRO/TNA (I can't bring myself to call it the TNA). Incidentally, the RN expected to adopt USN submarine weapons in wartime, which is why it was a very early adopter of digital (hence reprogrammable) submarine fire control systems.

As for the anti-boomer mission, SUBROC was conceived in 1956, before any anti-SSBN mission was important. I think that it began as a shore bombardment weapon, and it had a secondary shore bombardment mission (the warhead could be fused in different ways). I would guess that it was adapted for ASW as the USN began to worry about Soviet SSNs; it was difficult to make a homing torpedo effective at the required speed (Mk 48 was in the future). That is also why the USN adopted the Mk 45 ASTOR nuclear torpedo. Remember that nuclear weapons were treated a lot more casually in the late 1950s and early 1960s than later.

 

[drejr]

I wonder if a version of the Mk-48 torpedo could've been developed as a payload for the SUBROC?

The Mk48 is bigger than Subroc.

It's actually somewhat smaller but only somewhat.

SUBROC grew from the general idea of Nobska's "pocket Polaris" but I'm not sure it had an airburst fuse. I've seen some sources that claim that and others like Polmar that claim it was only considered after the failure of Regulus II then quickly dropped.

Concepts competing with SUBROC in the 50s were Marlin, which was definitely a multipurpose weapon with land-attack capability, and Wet ASROC.

There were a number of studies of conventional SUBROC variants or alternatives in the late 60s and early 70s but they weren't considered sufficiently effective for production.

 

[T. A. Gardner]

Friedman in Naval Weapons states that SUBROC was considered a "bombardment rocket" and could be fitted with an air burst fuze for land targets. The reason a torpedo carrying version wasn't adopted appears to be that the CEP at the ranges the weapon would be used at was so large that a conventional homing torpedo had a very low probability of detection and attack before its battery ran down.

 

[Dilandu]

Well, USSR have "Vodopad" sub-launched rocket for 533-mm tubes; it existed in both nuclear and conventional versions (with small acoustic torpedo). On the other hands, long-range "Veter" for 655-mm tubes, existed only in nuclear version.

 

[Sferrin]

I wonder if a version of the Mk-48 torpedo could've been developed as a payload for the SUBROC?

The Mk48 is bigger than Subroc.

It's actually somewhat smaller but only somewhat.

Yeah, 3700lb vs 4000lb for Subroc but you still aren't even coming close to fitting a Mk48 on a Subroc booster and fitting it in a torpedo tube.

 

[NMaude]

I wonder if a version of the Mk-48 torpedo could've been developed as a payload for the SUBROC?

The Mk48 is bigger than Subroc.

It's actually somewhat smaller but only somewhat.

Yeah, 3700lb vs 4000lb for Subroc but you still aren't even coming close to fitting a Mk48 on a Subroc booster and fitting it in a torpedo tube.

I wonder if a modified Mk-48 could be mounted on a Mk-72 booster with a suitable adaptor (Containing a retarder parachute) and fired from a MK-41 VLS?

 

[TomS]

I wonder if a modified Mk-48 could be mounted on a Mk-72 booster with a suitable adaptor (Containing a retarder parachute) and fired from a MK-41 VLS?

No. A standard Mk 48 plus Mk72 booster would be much longer than a strike-length VLS canister.

In practice, you'd have to use a radically cut down torpedo along the lines of the abandoned half-length Mk48. Add a nosecap and parachute pack to give the payload a fighting chance of surviving a high-speed impact with the water. At which point the torp itself probably has to be cut down to at most 12 feet (from 19). Given that fuel alone accounts for a good six feet of the existing torpedo, either you also cut down the warhead significantly or you end up with basically no fuel at all.

 

[Yellow Palace]

If you wanted something bigger than a lightweight torpedo on an ASROC/SUBROC-type system, you'd probably be better off starting with something like the Mark 37 torpedo as a payload.

 

[Dilandu]

Hm, I wonder what if instead of "proper" torpedo we use a set of homing depth charges, with the ability to maneuver while they sunk?

 

[TomS]

If you wanted something bigger than a lightweight torpedo on an ASROC/SUBROC-type system, you'd probably be better off starting with something like the Mark 37 torpedo as a payload.

In form factor, definitely. But Mk37 is just way too slow to be effective. It couldn't chase down a nuke sub that started running when it heard the splash.

Hm, I wonder what if instead of "proper" torpedo we use a set of homing depth charges, with the ability to maneuver while they sunk?

Way too small a search footprint.

 

[DWG]

Hm, I wonder what if instead of "proper" torpedo we use a set of homing depth charges, with the ability to maneuver while they sunk?

I suspect you're going to run into limitations of range vs CEP, or rather range versus how good your targeting fix is at a range where you're using an ASW rocket rather than a torpedo. Anything deployed ballistically is stuck with hoping the target is close enough to both detect and engage when it enters the water, and I suspect that's going to favour the torpedo rather than the depth charge. Which is not to say that a pattern of guided depth charges isn't a viable design at shorter ranges, just that I think the lightweight torpedo is probably more flexible as range increases.

 

[Dilandu]

I suspect you're going to run into limitations of range vs CEP, or rather range versus how good your targeting fix is at a range where you're using an ASW rocket rather than a torpedo. Anything deployed ballistically is stuck with hoping the target is close enough to both detect and engage when it enters the water, and I suspect that's going to favour the torpedo rather than the depth charge. Which is not to say that a pattern of guided depth charges isn't a viable design at shorter ranges, just that I think the lightweight torpedo is probably more flexible as range increases.

Hm, another probability; a dual anti-submarine munition.

* The first component, is a acoustic buoy (or even several of them) that fell in water and scan for submarine.
* The second component is a loitering (with glider wings) homing depth charge, which stay in air until buoys find the submarine, and then it just drop on it.

 

[TomS]

Hm, another probability; a dual anti-submarine munition.

* The first component, is a acoustic buoy (or even several of them) that fell in water and scan for submarine.
* The second component is a loitering (with glider wings) homing depth charge, which stay in air until buoys find the submarine, and then it just drop on it.

There was a proposed ASW Tomahawk that would basically do this. It would fly out to the last known datum, lay a field of a half-dozen or so sonobouys, relocalize the target, then drop a lightweight homing torpedo on the updated location. Given how tricky sonobouy interpretation can be, I was never sure how that third step was supposed to work.

 

[Sferrin]

Hm, another probability; a dual anti-submarine munition.

* The first component, is a acoustic buoy (or even several of them) that fell in water and scan for submarine.
* The second component is a loitering (with glider wings) homing depth charge, which stay in air until buoys find the submarine, and then it just drop on it.

There was a proposed ASW Tomahawk that would basically do this. It would fly out to the last known datum, lay a field of a half-dozen or so sonobouys, relocalize the target, then drop a lightweight homing torpedo on the updated location. Given how tricky sonobouy interpretation can be, I was never sure how that third step was supposed to work.

That would be awesome.

 

[Firefinder]

Hm, another probability; a dual anti-submarine munition.

* The first component, is a acoustic buoy (or even several of them) that fell in water and scan for submarine.
* The second component is a loitering (with glider wings) homing depth charge, which stay in air until buoys find the submarine, and then it just drop on it.

There was a proposed ASW Tomahawk that would basically do this. It would fly out to the last known datum, lay a field of a half-dozen or so sonobouys, relocalize the target, then drop a lightweight homing torpedo on the updated location. Given how tricky sonobouy interpretation can be, I was never sure how that third step was supposed to work.

That sounds incredibly awesome and I will love to see a source so i can read more.

And take notes for future ideas...

 

[T. A. Gardner]

Hm, another probability; a dual anti-submarine munition.

* The first component, is a acoustic buoy (or even several of them) that fell in water and scan for submarine.
* The second component is a loitering (with glider wings) homing depth charge, which stay in air until buoys find the submarine, and then it just drop on it.

There was a proposed ASW Tomahawk that would basically do this. It would fly out to the last known datum, lay a field of a half-dozen or so sonobouys, relocalize the target, then drop a lightweight homing torpedo on the updated location. Given how tricky sonobouy interpretation can be, I was never sure how that third step was supposed to work.

That sounds incredibly awesome and I will love to see a source so i can read more.

And take notes for future ideas...

I can take an informed guess but I'm not going to post it here because I'm not sure it's not classified... Let's just say if you have enough processing power with a computer things can be done to make it work.

 

[Hood]

I can take an informed guess but I'm not going to post it here because I'm not sure it's not classified... Let's just say if you have enough processing power with a computer things can be done to make it work.

You probably could do this fairly easily today, in the 1980s it might have been a step too far.

Besides it seems a very slow response system, fine if you can detect those noisy older Soviet subs from a way off but if one pops up within SSM range of your taskforce/convoy I'm not sure you would want to waste time hoping the Tomahawk ASW is going to get its sonobuoy data correct and then hope the torpedo is 100% reliable on entering the water and acquires.
Whether those buoys are active or passive is going to make a difference too, if active, the sub is going to do what it can to get under a layer or sprint away as soon as it hears them.

 

[TomS]

That sounds incredibly awesome and I will love to see a source so i can read more.

And take notes for future ideas...

Having trouble finding it now. Would have been late 1990s, IIRC.

 

[drejr]

I've seen an ASW Tomahawk but it just dropped sonobuoys - no torpedo. Might be a different project.

 

[Firefinder]

That sounds incredibly awesome and I will love to see a source so i can read more.

And take notes for future ideas...

Having trouble finding it now. Would have been late 1990s, IIRC.

Shame, any idea od the project name or similar so we can do our own searching?

I've seen an ASW Tomahawk but it just dropped sonobuoys - no torpedo. Might be a different project.

Might have even been a different approach on the same project, a hunter killer set up instead of a unified one...

 

[TomS]

That sounds incredibly awesome and I will love to see a source so i can read more.

And take notes for future ideas...

Having trouble finding it now. Would have been late 1990s, IIRC.

Shame, any idea od the project name or similar so we can do our own searching?

Would have been in the trade press -- likely Defense News or Jane's. It was definitely a company proposal, not a Navy initiative. Probably around 1998 or so?

 

[Firefinder]

That sounds incredibly awesome and I will love to see a source so i can read more.

And take notes for future ideas...

Having trouble finding it now. Would have been late 1990s, IIRC.

Shame, any idea od the project name or similar so we can do our own searching?

Would have been in the trade press -- likely Defense News or Jane's. It was definitely a company proposal, not a Navy initiative. Probably around 1998 or so?

Welp off to the old search machine I go... Thanks boss, been hearign about the ASW Tomahawk but not much on it.

Ill post it here or in the Tomahawk thread if I find anything.

 

[TomS]

Friedman World Naval Weapons Systems 1997-1998 has a passing reference to it in the Antisubmarine Warfare | Missiles section (page 667):

UNITED STATES
Efforts to revive the Sea Lance (UUM-125A) program, canceled in 1989, failed. Tomahawk/Mk 50 has not attracted Navy funding.

This program name is sadly non-googleable.

 

[drejr]

Might have even been a different approach on the same project, a hunter killer set up instead of a unified one...

I'm not sure, it just came to mind because the patent mainly discusses some of the sonar tricks that have been hinted at.

 

[Yellow Palace]

In form factor, definitely. But Mk37 is just way too slow to be effective. It couldn't chase down a nuke sub that started running when it heard the splash.

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.

Hm, another probability; a dual anti-submarine munition.

* The first component, is a acoustic buoy (or even several of them) that fell in water and scan for submarine.
* The second component is a loitering (with glider wings) homing depth charge, which stay in air until buoys find the submarine, and then it just drop on it.

There was a proposed ASW Tomahawk that would basically do this. It would fly out to the last known datum, lay a field of a half-dozen or so sonobouys, relocalize the target, then drop a lightweight homing torpedo on the updated location. Given how tricky sonobouy interpretation can be, I was never sure how that third step was supposed to work.

Taking a wild guess, if the target has already been identified and classified, the missile can be sent out with its sonobuoys programmed to identify a single, very specific, frequency. The idea would be to pre-process the data with launch ship information to make finding that one submarine in that particular area of the sea easier, at the expense of being unable to find anything else. Which is probably a perfectly good tradeoff for an ASW weapon.

 

[TomS]

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.

True. And there were efforts along those lines -- NT37C was a Mk 37 with the Otto fuel engine of a Mk 46, capable of at least 34 knots. That was a late 1960s, early 1970s effort. (NT37D and E were progressive seeker/guidance upgrades in the early 1980s.)

 

[Hood]

Friedman in British Submarines in the Cold War mentions in relation to British interest in a non-nuclear SUBROC, that it was impossible to fit a torpedo-armed SUBROC inside American torpedo tubes.

 

[timmymagic]

Presumably Mk 46 would have been considered pretty marginal against deep targets, given the need to drop by parachute, descend to depth and start a search pattern it would have been a slower engagement than dropping a W-55 and blasting an entire area.

If I remember correctly one of the major issues with ASROC was that a nuc sub moving at speed would be outside of the Mk.46's sonar detection range by the time it had had its trajectory calculated, been readied for launch, fired, arrived over target, descended on parachute, landed in the water, stabilised itself then gone into search mode....

 

[publiusr]

There any work not on torpedos, but reverse depth charges released from a sub to float up towards an enemy ship passing over?

 

[TomS]

There any work not on torpedos, but reverse depth charges released from a sub to float up towards an enemy ship passing over?

Closest thing I've ever heard of are rising mines, which are laid (or tethered) on the sea floor in deep water and then rise up to attack ships. They're often propelled (either a torpedo or a rocket payload) because drifting up from deep water makes it fairly difficult to hit a ship without some form of steering.

 

[NMaude]

They're often propelled (either a torpedo or a rocket payload) because drifting up from deep water makes it fairly difficult to hit a ship without some form of steering.

There's the US Mk-60 CAPTOR for example.