Calling all Skipjack-class (SSN-585) fans!

[571Nautilus]

Working on Moebius to consider a line of 1/144 scale cold-war era sub kits. You ping on 'em too ... can only help.

David Douglass Merriman lll

That would be fantastic. I'm going there now to 'ping'!

[mike_espo]

Just received my micromir 1/350 Skipjack kit.

She looks great. She's next up after Zumwalt.

[Tom Dougherty]

Just received my micromir 1/350 Skipjack kit.
She looks great.

It may *look* great in the box, but just be aware that the MicroMir Skipjack kit has a MAJOR ERROR. The indentations in the aft hull that indicate the locations for placement of the upper and lower rudders are totally wrong. If you assemble the kit and place the rudders in those areas the leading edge of the rudder will align with the leading edge of the stern planes, and the trailing edges will not align, since the rudders are not as long in the chord as the stern planes. In fact, it is the trailing edges of the rudders and stern planes that should align; the leading edges do not. The odd thing is that the kit drawings have it correct, but the kit itself has you placing the rudders in the wrong locations too far forward on the hull, if you use the indicated indented locations on the hull pieces. Easy to fix; fill in the shallow indentations for the rudders, drill a small hole in the correct location and in the rudder itself, and use brass wire to place and hold the rudder correctly in place.

At least you seem to have received a complete kit from MicroMir, my kit was missing the photo etch. Not too impressed with that fact, either.

See photo of a MicroMir kit below assembled with the rudders in the wrong locations, and the Moebius kit, with correct placement. Obvious once you see it. Also, I have put a Skipjack drawing below that illustrates the point:

[mike_espo]

Thanks Tom. Probably would have missed that.

[Maarten Sch�nfeld]

I missed it for sure! Thank you Tom, I will definitely correct my model on this.

[mike_espo]

What did you guys think of Ken Sewell's All Hands Down?

His theory is the Russians were responsible for the sinking of the USS Scorpion almost 50 years ago.

I wasn't crazy about it. Don't buy into Conspiracy theories.

[Tom Dougherty]

An analysis of the acoustics from the Azores hydrophone array by expert Bruce Rule (former US Naval officer in the acoustics area ) has totally eliminated the conspiracy theory aspect of Ken Sewells' Scorpion theory. The acoustic traces as well as the wreckage show no sign of a Soviet torpedo, instead a single low order explosive event (possibly a battery, due to both the state of the recovered battery material and the nature of the acoustic pulse) followed several minutes later by a much larger set of acoustic events, which most likely is the implosion of the hull at the frame where the aft cone junction was located in the Skipjack class. The initial low order event would have instantaneously incapacitated the crew (estimated, IIRC, to be equivalent of around 20 lbs of TNT) due to the overpressure in the enclosed hull space. The overpressure would be sufficient to render the crew unconscious and probably also had enough force to kill (50 PSI overpressure is uniformly fatal to humans). The submarine would have slowly drifted down and was estimated to have the weakest part, the cone junction, collapse forward into the machinery space at around 1500 ft depth. The supersonic water ram from this collapse is theorized to have blown out the operations compartment and sheared the bow off, which is consistent with the state of the wreckage as it is now. A key finding was that in the several minute interval between the first event and the event believed to be the hull collapse, there was no movement of the emitting source. Bruce published this all in a book (not widely distributed) and I wrote an article based on his research for the SubCommittee. Happy to send that to you if you would like.

Sewell has written two books. The first about the lost Soviet Golf II class K-129 was also a Sewell Conspiracy Theory book, postulating that the K-129 was only 350 miles from Hawaii when it sank, and was trying to emulate a Chinese submarine in launching a nuclear missile toward Hawaii to start a US-Sino war. He based this on a set of dives made by the Trieste II bathyscaphe at that site. It was revealed a few years ago that the Trieste II dive that he thought was on the K-129 wreck was actually a dive to recover a sunk film capsule from the first KH-9 satellite. It's on the CIA web site and can be downloaded. Called "An Underwater Ice Station Zebra". Sewell wanted to sell sensationalist books with the very thinest veneer of research and a heaping helping of speculation. Problem with "All Hands Down" is that the survivor families of the Scorpion are subjected to the idea that the last minutes of their sailors lives were spent in a life and death struggle to avoid a Russian torpedo. Instead it was a tragic accident almost certainly due to a technical issue with battery charging and ventilation, and the crew probably had no perception of it. They would have been rendered instantaneously unconscious by the initial event.

[mike_espo]

Thanks Tom. Actually I really disliked the book and gave it a 1 star review on Amazon.

Where exactly was the aft cone junction?

Would love to see your article, if that's ok.

[Tom Dougherty]

Mike, email me at ascdr15@gmail.com.

[Vepr157]

In U.S. Submarines since 1945, Friedman claims that the Scorpion tested a reactor coolant scoop mounted forward of the sail (similar to those supposedly installed on the Narwhal's lower hull). Would anyone happen to have information about this scoop?

Jacob

[Tom Dougherty]

Unclear if it was a test for a scoop installation (fin) forward of the sail or if the system was actually installed. Apparently it exacerbated the snap roll problem on Scorpion, which was already an issue due to the existing large sail area. I can't imagine trying to pipe high pressure sea water from the area forward of the sail all the way back to the engineering spaces where the condensers are located.

BTW, an updated version of Friedman's "US Submarines since 1945" book is planned for 2018. It will include classes (Seawolf & Virginia) that were either not included or were in early development stages when the original was published.

[Vepr157]

I love Friedman's book (and am very excited there's going to be a second edition) but sometimes it seems he gets what was proposed for a particular submarine and how it was actually built confused. For example, he states that the Scorpion had a direct-drive turbine. This is very unlikely because she wasn't any larger than the other Skipjack and I have the Piping TAB (which covers all but the Skipjack) and the Scorpion does not appear to have any substantial changes in her propulsion machinery. I wonder if the prototype coolant scoop is the same.

Is there any evidence other than Friedman's book which shows that the Narwhal had coolant scoops?

Jacob

[Tom Dougherty]

Yes, Narwhal definitely had the coolant scoops for the S5G Natural circulation reactor, but as far as I know, it was a one off. With the SubSafe program the US Navy (unlike the Russians) decided against piping large volumes of high pressure sea water into the interior of a submarine. Narwhal also had a much larger direct drive turbine, which actually expanded due to heat (and was mounted to accommodate expansion) at high power. The interior layout was quite different from the other Sturgeon class subs. In other nuclear submarine classes, the seachest openings that duct seawater to cool the secondary loop condensate are kept as short runs.

To my knowledge, all of the Skipjack class had the same interior layout. The more I thought about it, the stranger it seemed to have a scoop forward of the sail and piping high pressure salt water all the way to the machinery area to the condensers to cool the two secondary steam loops. Where would you duct the sea water piping through the various compartments? It would violate SubSafe design. The snorkel air ducting problem from the sail was solved by running it through the small "hump" abaft the sail back to the engineering spaces. Later classes (Permit, Sturgeon & LA) solved the ducting problem by moving the diesel out of the aft machinery spaces to forward near the torpedo room.

I have a pretty complete set of 3 large (4 feet by 2 feet) drawings of the Skipjack class which shows hull sections, exterior and interior layout including the machinery and reactor spaces and layout. The reactor compartment shows the S5W with twin steam generators on either side of the reactor. The twin turbines, bull gear, thrust block and prop shaft and STG sets are also shown. Its one of a set of three very large sheets; I received these about 6 months ago.

[ArmchairAdmiral]

The initial low order event would have instantaneously incapacitated the crew (estimated, IIRC, to be equivalent of around 20 lbs of TNT) due to the overpressure in the enclosed hull space. The overpressure would be sufficient to render the crew unconscious and probably also had enough force to kill (50 PSI overpressure is uniformly fatal to humans).

Would that pressure have penetrated through all decks, bulkheads, and WT doors to reach every crewman in every compartment? Weren't the boats designed to resist similar pressure from seawater in case of a flooded compartment?

[Tom Dougherty]

Would that pressure have penetrated through all decks, bulkheads, and WT doors to reach every crewman in every compartment? Weren't the boats designed to resist similar pressure from seawater in case of a flooded compartment?

The overpressure from an internal explosion would have instantaneously raised the air pressure in all compartments (assuming the WT doors are all open, as per normal operation). In this case the hull would have acted to keep the internal increase in pressure high, as there would be no place for the pressure to dissipate. An explosive overpressure of just 50 PSI above ambient air pressure is sufficient to render humans unconscious and subsequently dead from internal organ injuries. Compare this to water pressure at 700 feet (Skipjack test depth), which would be around 300 PSI. The hull was designed to withstand this water pressure (and then some, as a safety factor).

The later classes of (such as Skipjack) SSNs have relatively few compartments vs. US WWII fleet submarines and flooding of one larger compartment in an SSN will probably sink the submarine, as reserve buoyancy figures & compartment numbers for modern US submarines are much less than those of WWII fleet boats.

[ArmchairAdmiral]

Thank you, Tom. One other question intrigues me--in regard to the initiating event, the two near-simultaneous explosions, if one was the battery, what was the other, and which came first?

[Tom Dougherty]

The detailed explanation is best derived by reading Bruce Rule's commentaries.
Here's a link to the entire set of sections (4) of technical data assembled by Bruce Rule on the Scoprion loss;
http://coloradosubvets.org/bruce-rules- ... on-theory/

These include the helicorder traces from the LaPalma hydrophones. Note Section 3 is printed upside down, why, I don't know. You can easily invert it.

A followup on the battery issue from a nuclear qualified officer who served on the Skipjack class SSNs.
http://www.iusscaa.org/articles/bruceru ... fficer.htm


Finally, here's a link to an article I wrote a few years ago, based on Bruce's research:
http://www.bonefishbase.org/wp-content/ ... orpion.pdf

[ArmchairAdmiral]

Very helpful, thanks much.

[Woodstock74]

Skipjack screw diameters: I see a reference from 1958/1959 of 15'. I'm assuming that's for the conventional 5-blade screw. Any ideas how accurate this number is? The follow-on 7-blade skewback...any ideas of its diameter?

[Vepr157]

Yes, the five-bladed propellers had a diameter of 15'0". There were several seven-bladed propellers, some with 15'0" and some 12'4". If you want more information, look up the following numbers up on https://fsg-20-ship-marine.parttarget.com/

SSN588-203-2113387
SSN588-203-2113387PC1
SSN588-203-2500463
SSN588-203-2540029
SSN588-203-2478480
SSN588-203-4352714PC1
SSN588-203-4252643PC1

Note that these are for the Scamp "class" (i.e. every submarine in the Skipjack class except the Skipjack herself), which had different propulsion machinery. However, I doubt the Skipjack's propeller was any different.