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Chuck Baker is a veteran US Navy submariner who served 011 fast attack submarines in the 1980’s and later served as a surface warfare officer in the early 1990s. Chuck’s background is in applied engineering and he holds a Master’s Degree in Mechanical and Aerospace Engineering. He currently works at NASA’s Jet Propulsion Laboratory’ as a senior systems engineer and is a team member on NASAs Mars Science Laboratory project.

Bruce Rule, for 42 years, has been the lead acoustic analyst at the Officer of Naval Intelligence. In 2003, wrote the Navy position-paper 011 the acoustic, dynamic and temporal characteristics of submarine pressure-hull a11d bulkhead collapse events. In 2009 he provided the Navy with the first reanalysis of acoustic detections of the loss of the USS SCORPION i11 40-year which confirmed that disaster was the result of a battery explosion.

The MIKE Class Soviet SSN K-278, lost on 7 April 1989

Fire at Sea. The Tragedy of the Soviet Submarine Komsomolets (Nato: MIKE) is a remarkable book about a remarkable submarine. Written by D. A. Romanov, the deputy chief designer of the MIKE, and copyrighted in 2006, the book (hereafter ROMANOV) provides detailed technical information on the design characteristics of the MIKE that could not have been published during the Soviet era.

It is not the purpose of this article to review ROMANOV but to discuss several important conclusions that are based on information in the book but which were not specifically addressed by the author.

As discussed in ROMANOV, MIKE was lost when a fire in the aft-most compartment (seven) melted non-metallic connections in the high pressure air and hydraulic lines allowing their release into that compartment which resulted in a (quote) blast furnace (end quote) with estimated pressures 20 times normal and combustion temperatures at least as high as 1600F (ROMANOV, pp. 103). Those conditions caused the titanium pressure-hull to recrystallize and burn through (breach) to permit flooding. Sea water near the stern was observed boiling.

The resulting flooding had progressed from compartment seven as far forward as compartment three when the MIKE sank down by the stern at 1708 local on 7 April 1989 in the far northeastern Norwegian Sea (73-43-l 7N, 13-15-51 E).

When the MIKE sank, five men were still onboard. Four entered the escape sphere in the sail which could not be released, probably because of the stern-down attitude which would have prevented the sphere from rising from its vertically-mounted containment area. According to the single survivor, that stern-down attitude increased sharply before lessening as the MIKE sank toward the bottom at a depth of 5530 feet.

The survivor from the sphere stated (ROMANOV, pp 171) that “suddenly there was a shock beneath us, like a bomb exploding, followed by a second vibration.” Although, as discussed in ROMANOV, there are alternate explanations for these two events, the most likely (not discussed in ROMANOV) is bottom impact, first by the stem and then by the rest of the submarine pivoting on the grounded stern. This sequence of events, which leveled the submarine -as confirmed by subsequent imagery and observations from Soviet MIR submersibles-released the escape sphere.

If the MIKE impacted the bottom I 0-degrees down by the stem and sank at about 13-knots, a value determined for USS STERLET (SS-392) during an instrumented sinking on 31 January 1969, then the two MIKE bottom impact events should have been separated by two to three seconds.

The released sphere-designed to hold the entire crew of 64-rose to the surface in “one to two minutes” where the pressure-seated topside hatch blew open permitting the survivor to escape. (A weight displacement analysis suggests about three minutes.) Another man, who also was ejected, died from his injuries while the other two in the sphere were either moribund or dead. They had failed to connect their emergency breathing systems and were overcome by toxic fumes and atmospheric over-pressure within the sphere which increased the toxicity of the fumes. The sphere, which then flooded and sank, was subsequently located about 300-feet from the MIKE wreck after rising and then sinking 5500-feet.

If the MIKE sank at 1 708 local and had the same measured 13-knot sink-rate as STERLET, bottom impact would have occurred at about 1712, a value consistent with then Soviet press reports of the surfacing of the sphere at about 1715.

The normal maximum operating depth for the titanium-hulled MIKE (test depth) was 1022m (3350-feet) with a never exceed depth of 1250m (4100-feet) and an estimated pressure-hull collapse depth of 1500m (4900-feet).

Page 175 of ROMANOV shows the photograph of a clock recovered from the MIKE wreck-site in 1992 and now on exhibit in the Russian Naval Museum in Saint Petersburg. That clock stopped at 17:22:30 or about 10-minutes after the probable bottom impact by the MIKE. This circumstance indicates the area within the MIKE pressure hull where the clock was located did not collapse until subjected to a pressure of 2,460 psi for those 10-minutes. Although the design pressure limit of the MIKE bulkheads (specifically those contiguous to compartments six and seven was 142 psi) (ROMANOV, pp. 102), the clock provides clear evidence that one bulkhead survived temporarily at about 17 times that pressure.

During the instrumented sinking of STERLET, the torpedo room bulkhead (the only sealed compartment) collapsed at a depth of 1200-feet, three times the test depth of the pressure-hull. The energy released by that event was equal to the explosion of 840 pounds of TNT at that depth.

Chapter 2 of COLD WAR SUBMARINES by Norman Polmar and K. J. Moore states that “the end (torpedo room) compartments of WWII US diesel submarines were rated at 1100-feet to fascilitate the use of the McCann rescue chamber” mated to the escape trunks in those compartments. See Note ( 1) The STERLET keel was laid down on 14 July 1943.

During a 1993 Russian survey of the MIKE wreck-site, a 20-foot hole was noted in the starboard-side of the first compartment, the torpedo room.

These circumstances indicate the clock was recovered either from the torpedo-room through that hole in the pressure hull or was ejected through the hole and recovered from the bottom. It is concluded the MIKE torpedo room bulkhead could withstand the same pressure as the pressure hull for the same reason as the STERLET design: to provide a refuge for those crew members unable to enter the escape sphere who might then be rescued via the MIKE forward escape trunk. The ROMANOV information indicates both the MIKE torpedo room pressure hull and the bulkhead between the torpedo-room and second compartment survived at a depth of 5530-feet for about l 0-minutes before collapsing.

It is probable the MIKE torpedo room pressure hull and bulk-head collapsed nearly simultaneously because the shock-wave from the first collapse event would have propagated through the pressure hull to the site of the second collapse at the speed of sound in titanium: 19,900 f/s (13,600 mph). Already stressed beyond design limits, the second collapse site could not have withstood the shock wave from whichever site collapsed first.

Based on an estimate that the hole in the torpedo room pres-sure hull was about 30-feet forward of the torpedo room bulkhead, the shock wave generated in the pressure hull by the first collapse would have reached the site of the second collapse-and triggered that collapse-in about 0.002-seconds, at least several multiples of the velocity of the water ram expanding at supersonic velocity through the torpedo compartment from the site of the first collapse.

The NOVEMBER Class Soviet SSN K-8, lost on 12 April 1970

As an addendum to the MIKE discussions, when the NOVEMBER Class Soviet SSN K-8 sank in the Bay of Biscay (47-25N, l9-40W)on 12(not ll)April 1970astheresultoffires, an associated collapse event was acoustically detected by a U.S. Navy Sound Surveillance System (SOSUS) array in the western Atlantic at 04:04:44Z. (This information was derived from acoustic data that has been in the public domain for more than 40-years but is reported here for the first time.) The K-8 also sank down by the stern with 52 of the crew still on board.

Analysis of the acoustic signal (bubble pulse frequency) indicates the collapse event occurred at a depth of 2020-feet (900-psi) with an energy release equal to the explosion of 1050-lbs of TNT at that depth. Based on the MIKE and STERLET data, that event was the collapse of the NOVEMBER torpedo room bulkhead and/or the torpedo room pressure hull. The published test-depth of the NOVEMBER Class was 985-feet.

Since it is probable all modern Russian submarines have torpedo room bulkheads with the same depth capability as their pressure hulls, and also have a reserve buoyancy greater than the volume of the torpedo room, the penetration of the torpedo room pressure hull by a weapon and the flooding of the torpedo room-even at significant depth-will neutralize the submarine weapon-firing capability but will not necessarily result in the loss of the submarine if the torpedo room was sealed prior to weapon impact.

Tehnical Comment

The empiric relationship that exists between the volume of a collapsing structure and the bubble pulse frequency (the compression-expansion cycle -oscillation rate -of air contained within the collapsing structure) permit determination of the depth of the event. In turn, that depth value and the bubble pulse frequency provide the size of the energy release-expressed in pounds of TNT-required to create that frequency at that depth.

Such forces are produced when potential energy in the form of sea pressure is converted almost instantaneously to kinetic energy, the motion of the water ram which enters structures that collapse at great depth at supersonic velocity. In the case of the NOVEMBER, all internal structures contiguous to yet unflooded areas were destroyed in less than 0.04-seconds as determined from the frequency of the collapse event bubble pulse.

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