RUR-5 ASROC and RUM-139 VL-ASROC (VLA)

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I was thinking in regards to the RUR-5 ASROC during the late 50s/early 60s was there any thought given to a super-ASROC? By super I mean a much larger launch booster sized to launch a 21" torpedo.
 
NMaude said:
I was thinking in regards to the RUR-5 ASROC during the late 50s/early 60s was there any thought given to a super-ASROC? By super I mean a much larger launch booster sized to launch a 21" torpedo.
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Not that I’m aware. It would involve six times the weight. What would be the goal?
 
Grebe (X-SUM-N-2) was actually based around a 21-inch torpedo payload (initially Mk 35, then the lightened Mk 41 or Mk 34). There were planned versions with ranges of 8,000-40,000 yards.

The main problem seems to have been that all of these outranged the detection capacity of existing sonars (less than 5000 yards), making them rather pointless. Then, when sonar performance improved and they revisited the idea with RAT and ASROC, lightweight torps were good enough to chase most sub targets.
 
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TomS said:
Grebe (X-SUM-N-2) was actually based around a 21-inch torpedo payload (initially Mk 35, then the lightened Mk 41 or Mk 34). There were planned versions with ranges of 8,000-40,000 yards.

The main problem seems to have been that all of these outranged the detection capacity of existing sonars (less than 5000 yards), making them rather pointless. Then, when sonar performance improved and they revisited the idea with RAT and ASROC, lightweight torps were good enough to chase most sub targets.
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Not sure I agree with that then, and we're definitely at the point now where you need a lot more range than you can get out of a 12.75" torpedo to do more than chase the submarine away.


Josh_TN said:
Not that I’m aware. It would involve six times the weight. What would be the goal?
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Well, a Mk37 or 2-cell DM2A4 is only twice the weight of a Mk54... 1500lbs versus ~800 (including the parachute pack, ~600 without it).

But the goal would be greater range than what you can get out of an LWT.
 
Scott Kenny said:
Not sure I agree with that then, and we're definitely at the point now where you need a lot more range than you can get out of a 12.75" torpedo to do more than chase the submarine away.



Well, a Mk37 or 2-cell DM2A4 is only twice the weight of a Mk54... 1500lbs versus ~800 (including the parachute pack, ~600 without it).

But the goal would be greater range than what you can get out of an LWT.
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If you need greater range, increase the size of the booster, not the torpedo. It would be better to just start out closer to the target in the air rather than increase the underwater run time. Mk54 performance is adequate, and I believe the mod 2 will adopt a lithium steam powered motor like the mk50, which will increase speed and acceleration.
 
Josh_TN said:
If you need greater range, increase the size of the booster, not the torpedo. It would be better to just start out closer to the target in the air rather than increase the underwater run time. Mk54 performance is adequate, and I believe the mod 2 will adopt a lithium steam powered motor like the mk50, which will increase speed and acceleration.
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The problem is that modern submarines like Yasen, Virginias, Astutes, etc, are capable of outrunning the LWTs even if they land practically on top of the sub.

Sub runs some 10km from where the ASROC lands, and then goes back to work.
 
My idea of super VLA would be one that launches a Mk-48 ADCAP using the SM-3 Block-II version of the Mk-72 launch booster.
 
Scott Kenny said:
The problem is that modern submarines like Yasen, Virginias, Astutes, etc, are capable of outrunning the LWTs even if they land practically on top of the sub.

Sub runs some 10km from where the ASROC lands, and then goes back to work.
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I believe that mk 54 uses a mk 46 propulsion setup and achieves a speed in the mid 40s. No boat is outrunning that. The mod 2 version is going to adopt the steam powered engine of the mk50, which increases top speed and acceleration. That seems like a better solution to me.

EDIT: also presumably there is an option to simply fire a second ASROC in front of the boat. A sub at flank is blind.
 
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Scott Kenny said:
Not sure I agree with that then, and we're definitely at the point now where you need a lot more range than you can get out of a 12.75" torpedo to do more than chase the submarine away.
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In 1957, RAT with a 10-inch Mk 43 Mod 4 torpedo could run down an 11-knot sub, going up to 16 knots for the projected Mod 6 torpedo. That would not deal with the 30-knot November SSNs just entering construction, but the vast majority of threat subs at the time would still be Zulus or Whiskeys. which would be caught. The big problem was that RAT could not reliably put the torpedo close enough to the aimpoint to leave it in a favorable geometry to engage the sub.

ASROC fixed the accuracy problem with larger fins, and simultaneously upgraded to the larger diameter Mk 44 torpedo. But by that point, the torpedo was an afterthought -- ASROC was always intended to be mainly a nuclear depth bomb delivery system. I don't care how fast a sub runs, it can't outpace a ~Mach 1 rocket with a nuke on it.
 
TomS said:
Red Shark is very much in the same class as VLA and the Type 07 -- range somewhere between 20 and 40 km, depending on source. The Chinese Yu-8 also seems to be in the same ballpark, maybe 50 km but still nowhere close to the range of the Indian SMART. All of these missiles, aside from SMART, can be targeted from onboard sensors, at least in theory (50 km is pushing it, especially since Yu-8 has a much shorter ranged payload than the Western designs.)

I sincerely cannot figure out the use case for SMART, but I'm sure it makes sense to the Indians.
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Maybe make it easier for BAMS to stay on station longer by having the weapons off-board?
 
NMaude said:
My idea of super VLA would be one that launches a Mk-48 ADCAP using the SM-3 Block-II version of the Mk-72 launch booster.
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A Mk-48 weighs nearly 4,000lbs. If you want longer range just bring back Sea Lance.
 
NMaude said:
The Mk-72 has a thrust somewhere around 50-60,000Lb.



I know but what I suggested uses already existing hardware.
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I very much doubt a current Mk 48 can survive being flung out of a launch tube by a rocket and then dropped back in the water at high speed. It was never designed for those sorts of stresses.

Now, when the Navy talked about a less expensive heavyweight torpedoes (RAPTOR) earlier this year, they hinted at alternative launch platforms, but that is almost certainly a cheap anti surface torpedo, not an ASW one.

There's also a cost issue. One Mk 48 is >$5 million. Plus $1 million for the booster, plus whatever changes are needed to allow it to survive the new environment, and suddenly we are looking a weapon costing nearly as much as an early SM-3.
 
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TomS said:
I very much doubt a current Mk 48 can survive being flung out of a launch tube by a rocketand then dropped back in the water at high speed. It was never designed for those sorts of stresses.
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I don't know what the launch acceleration would be but given how heavy the Mk-48 is it's probably low, that being said some redesign of the Mk-48's internal components might be needed. As for entry into water it wouldn't be high speed due it using a parachute (Just like with the Mk-46/54 does in the VLA) but the Mk-28 torpedo stabiliser is probably too small so new, larger parachute would be needed.

TomS said:
There's also a cost issue. One Mk 48 is >$5 million. Plus $1 million for the booster, plus whatever changes are needed to allow it to survive the new environment
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True but such a weapon would probably be used for higher value targets such as an SSBN for example.
 
NMaude said:
True but such a weapon would probably be used for higher value targets such as an SSBN for example.
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If you get close enough to drop a super ASROC onto an SSBN, either you got so unbelievably lucky the entire crew needs to buy lottery tickets in every port or that boomer captain needs to die because he's a danger to everyone in the ocean.
 
Scott Kenny said:
If you get close enough to drop a super ASROC onto an SSBN, either you got so unbelievably lucky the entire crew needs to buy lottery tickets in every port or that boomer captain needs to die because he's a danger to everyone in the ocean.
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Good points however I was just using the SSBN as an example of a high-value target for use as a rocket-boosted Mk-48 could be used to destroy.


TomS said:
Plus $1 million for the booster
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I have a hard time believing that a Mk-72 rocket-booster would cost $1 million (The most expensive part of a missile is its GCU).
 
NMaude said:
The Mk-72 has a thrust somewhere around 50-60,000Lb.
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960lbs of propellant and a burn time of ~7 seconds. Thrust is probably closer to ~38k and that's with an ISP of 275. Not sure how far a Mk72 would throw a Mk48 (and the airframe to tie it together, parachute, structural mods, nosecaps, etc.), but I doubt it would be worth the hassle.
 
NMaude said:
I have a hard time believing that a Mk-72 rocket-booster would cost $1 million (The most expensive part of a missile is its GCU).
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Its not easy to break out, but if the price of an SM-6 is around $4.4 million and the cost of an SM-2 Block IIIC conversion kit is $2.4 million (both TWZ numbers), then the Mk 72 is easily in the ballpark of $1 million.
 
sferrin said:
(and the airframe to tie it together,
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I thought about what you'd use for the airframe and it occurred to me that if you used the SM-3 Block-II version of the Mk-72 booster then a modified tail-control section from the SM-3 Block-II.

sferrin said:
but I doubt it would be worth the hassle.
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Probably not but it was an interesting idea to think about.

Scott Kenny said:
The problem is that modern submarines like Yasen, Virginias, Astutes, etc, are capable of outrunning the LWTs even if they land practically on top of the sub.
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Maybe the USN should look at reintroducing a medium caliber torpedo, basically a homing 18" torpedo designed to be rocket-launched like with the VLA.
 
NMaude said:
The Mk-72 has a thrust somewhere around 50-60,000Lb.



I know but what I suggested uses already existing hardware.
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That assumes the booster and mk 48 fit a Mk 41 and that a mk 48 can survive the thrust, neither of which is a given or in the first case likely.
 
NMaude said:
I don't know what the launch acceleration would be but given how heavy the Mk-48 is it's probably low, that being said some redesign of the Mk-48's internal components might be needed. As for entry into water it wouldn't be high speed due it using a parachute (Just like with the Mk-46/54 does in the VLA) but the Mk-28 torpedo stabiliser is probably too small so new, larger parachute would be needed.



True but such a weapon would probably be used for higher value targets such as an SSBN for example.
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Why would an escort ever be near an SSBN? I am struggling to see a scenario where two or three VLAs could not do a better job than a mythical heavyweight torp on a booster.
 
Josh_TN said:
That assumes the booster and mk 48 fit a Mk 41
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It would almost certainly need a new launcher.

Josh_TN said:
and that a mk 48 can survive the thrust
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It's likely that some sort of structural modifications to the design would be required but given how heavy a Mk-48/Mk-72 combination (And the weight of the airframe that would mate the Mk-72 with the Mk-48) launch acceleration may be fairly low (~5-6Gs maybe).

Josh_TN said:
Why would an escort ever be near an SSBN?
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I mentioned the SSBN as an example of a high-value target that would justify such a weapon.
 
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NMaude said:
Maybe the USN should look at reintroducing a medium caliber torpedo, basically a homing 18" torpedo designed to be rocket-launched like with the VLA.
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I mean, the Mk37 was basically just that. 19" weapon that had some 1" spacers around the outside to let it swim out of a 21" torpedo tube, and it's half the length and weight of a Mk48 (or a WW2 Mk14).

And modern helicopters have enough horsepower to carry a ~1500lb weapon plus all the sonar gear, so you can still use the same torpedoes between ASROC, helo, and ship launched. Just replace the Mk32 triple tube launchers with a single 21" tube like they did in the 1970s on the FRAMcans (or a single 21" tube in addition to the Mk32 triplets).

Looking at things the other way, it might be interesting to install a couple of 12.75" torp tubes to use against patrol craft etc in the littorals. Targets not big enough to use a Mk48 on if you have something smaller.
 
Looks like a patent for the ASROC.....

US3636877A - Antisubmarine missile - Google Patents

1. In an underwater missile that is launched from a conventional missile launcher with a conventional booster and underwater weapon attached thereto, wherein this improvement comprises an adapter for said underwater weapon comprising the combination of: A CLAMSHELL SECTION PROVIDED WITH EXTERNAL...
patents.google.com
 
zjz said:
Looks like a patent for the ASROC.....

US3636877A - Antisubmarine missile - Google Patents

1. In an underwater missile that is launched from a conventional missile launcher with a conventional booster and underwater weapon attached thereto, wherein this improvement comprises an adapter for said underwater weapon comprising the combination of: A CLAMSHELL SECTION PROVIDED WITH EXTERNAL...
patents.google.com
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No, this is something similar but different. The tail shown is Tartar/Standard. I think this might be an alternative concept designed to fit Tartar launchers like the Mk 11 and Mk 13.
 
TomS said:
No, this is something similar but different. The tail shown is Tartar/Standard. I think this might be an alternative concept designed to fit Tartar launchers like the Mk 11 and Mk 13.
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I went back and read this more closely.
It is in fact described as an "Antisubmarine Terrier" with a range significantly longer than ASROC.

invention is known, is intended to complement the antisubmarine weapons presently in use and deliver a torpedo or depth charge at underwater targets to ranges representing a significant increase over presently known systems, the maximum range of a comparable system presently in use is approximately 10,000 yards. A modified nuclear warhead may also be carried by Antisubmarine Terrier described below.
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It was capable of being launched from existing Terrier launchers like the Mk 10. Of course some of these also could launch ASROC but that was a much smaller missile than Terrier. I feel like this might be able to reach out to a convergence zone.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1, a missile 10 which is launched with the Terrier rocket booster 12 from a conventional Terrier launcher, not shown. Immediately after launch the missile booster assumes a ballistic path for the first few seconds of boost, at the end of which the missile l0 separates from the booster at a velocity of approximately 3,000 feet per second, the point of booster separation being indicated at point A in FIG. 1.
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The drawings omit both the Terrier booster and the Terrier launcher but this seems to be an attempt to come up with something substantial better than ASROC as carried in Terrier launchers. Not for Tartar, in hindsight, because the diameter of the clamshell section is much wider than the fuselage of a normal Tartar. That's due to the incorporation of drag brakes for slowing the payload to acceptable speeds (ASROC uses a parachute instead.) plus, not enough volume left for a full Tartar motor.
 
Since the RUM-139 is a missile and not a rocket that would mean it's the Anti-Submarine MISsile or ASMIS, perhaps not the best acronym;):D.
 
Just circling back to mention that Friedman's US Naval Weapons notes that there were several longer-ranged ASROC concepts, variously referred to as Extended-Range ASROC (ERA) or Long-Range ASROC (LASROC) beginning in 1962, to exploit the notional bottom-bounce range of SQS-26. None came to fruition, and he doesn't mention this ASW Terrier from 1964, but it's probably part of the same push. This was just in time for the first DLGs with SQS-26 (the Belknap class), which I believe were ultimately the only ships with both SQS-26 and Terrier.
 
I did not realize there are limitations to some of the USN missile launcher systems, like what ordnance can be launched, and what cannot be launched by a particular launcher..

This makes me recall that one of the Harpoon missile design criteria was that it has to be compact enough to be launched by all existing launcher systems at that time (late 1960s - early 1070s), including the ASROC matchbox launchers!

ASROC got its VL treatment, but not Harpoon! :rolleyes:
 
NMaude said:
Now, that, is a good point! Why didn't the USN go for a VLH (Vertical Launch Harpoon)?
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Lots of factors. The existence of Tomahawk Anti-ship Missile was probably the biggest -- if you're going to use up a VLS cell, might as well have a more capable missile. Relatedly, VLS cells were limited for quite a while. Using them for Harpoon meant fewer available for Standards (which is probably also why Mk 26 never got Harpoon, despite it being easy technically.) And Harpoon was compact and easy to install on deck, unlike ASROC or Tomahawk.
 
NMaude said:
I was thinking in regards to the RUR-5 ASROC during the late 50s/early 60s was there any thought given to a super-ASROC? By super I mean a much larger launch booster sized to launch a 21" torpedo.
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The ASW version of UGM-89 Perseus/STAM was supposed to carry a Mk 37-sized 21" torpedo using the Mk 48 seeker.
 
A Tentative Fleet Plan said:
The ASW version of UGM-89 Perseus/STAM was supposed to carry a Mk 37-sized 21" torpedo using the Mk 48 seeker.
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MK 37 was actually 19 inches in diameter, and the STAM proposal was for a shortened version, less than 150 inches long and weighing less than 2,000 lbs. STAM, of course, was huge -- 30 inches in diameter, 300 inches long, and something over 6,000 pounds.
 
TomS said:
STAM, of course, was huge -- 30 inches in diameter, 300 inches long, and something over 6,000 pounds.
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If the UGM-89A had entered development, testing and production wasn't there going to be a dedicated SSN class to carry it with its' own VLS silos?
 
Something I've been wondering is why the VLA's payload (Either the Mk-46 or Mk-54 12.75" torpedo) wasn't fully encapsulated instead of just the aft portion of the payload? IIRC the Japanese equivalent of the VLA has its' torpedo-payload fully encapsulated.
 

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