Acoustic Analysis of the Death of USS Scorpion

Hello All. My first post, so be gentle. I found this posted on one of the Submarine Bulletin Boards that I often surf. I have heard all of the stories and theories about Scorpion's death, but this is the first official acoustic analysis that I have found. As I read it, I foound it alittle cold when describing the collapse of her pressure hull. All I could think about was her crew, I hope that most were so engaged in fighting the casualty that they were un aware of what was happening. But there were those that stood at their stations, and watched for the entire casualty the depth gage as the boat went deeper into the abyss. Knowing that they were approaching their crush depth and were going to die. It brought a tear to my eye. "Sailors, rest your oar."




Summary Analysis of SCORPION Acoustic Data-Bruce Rule
Date: Thu Jan 7, 2010 9:39 pm ((PST))

Having completed the analysis of all available SCORPION acoustic data, the following summary is provided. Post as useful.

When the US nuclear submarine SCORPION was lost in the East Central Atlantic on May 22, 1968, the event produced a series of acoustic signals that were detected by seafloor sensors on both sides of the Atlantic.

The US Air Force Technical Applications Center (AFTAC) determined the point of origin of these SCORPION signals by comparing the detection times at three sensor sites. The derived position was where the SCORPION wreckage was subsequently discovered at a depth of 3,380m (11,100 ft). The Chief of Naval Operations message date-time-group 311840Z May 1968 acknowledged the AFTAC contribution.

The first reanalysis of the SCORPION acoustic data in 40-years identified the following new information in 2008:

- The initiating events responsible for the loss of SCORPION were two small explosions that occurred one-half second apart at 18:20:44Z on 22 May 1968 and were contained within the submarine’s pressure-hull. The source of these explosions, which are estimated to have been equal to the explosion of not more than 10 kg (22 lbs) of TNT each, cannot be determined from analysis of the acoustic data.

- These explosive events prevented the crew from maintaining depth control. SCORPION slowly sank to 1530-feet at which depth the pressure-hull and all internal bulkheads collapsed at 18:42:34Z on May 22, 1968 in one-tenth of a second with a force equal to the explosion of 6,000 kg (13,200 lbs) of TNT.

- This energy was produced by the essentially instantaneous conversion of potential energy in the form of 680 psi pressure on the entire SCORPION hull to kinetic energy, the motion of the intruding water-ram which entered the pressure-hull at supersonic velocity.

- During the 111.6-second period when it was conjectured in 1968 that SCORPION had reversed course to deactivate a torpedo that had become active in its launch tube, the horizontal position of the submarine changed less than 100-feet. This time-of-detection based analysis refutes the course reversal/active torpedo theory.

- During the 200-second period following pressure-hull collapse, 17 additional acoustic events were detected. These events were produced by more pressure-resistant structures that survived within the wreckage to collapse at greater depth. Six of these events were produced by the collapse of the SCORPION torpedo-tubes near the following depths:
3370-, 3750-, 3810-, 3950-, 4510- and 4570-feet.

There were no explosions from a torpedo or any other source external to the SCORPION pressure-hull. SCORPION was lost because of an onboard problem (the two internal explosions) the crew could not overcome.

There was no involvement by Soviet forces as conjectured in some popular accounts of the loss of SCORPION. There were no acoustic detections of a torpedo as would have occurred had a Soviet weapon operated at 40-knots as postulated by one popular account.

The technical documents upon which the above conclusions are based, which total nearly 50-pages, were provided to the Chief of Naval Operations (OPNAV N87), the Commander Submarine Force, the Office of Naval Intelligence and the Naval Historical Center (NHC). Freedom of Information Act requests for this unclassified information should be sent to the NHC, specifically the originator's letters of 14 Mar, 3 Apr and 28 Oct 2009.

Kudos on a great first thread, nicely presented.

Is there any more information available on this, what was the "established" cause for this event?

Thank you!

The long established "cause" was a torpedo malfunction, causing it to become active in its tube. THis is called a "hot run." To combat a casualty such as this, is for the boat to make a 180 turn which would cause the weapon's on board safety sustem to kick in and shut itself down. THe theory was that the crew either acted to late, or the safety malfunctioned as well, causing the weapon to explode in its tube. The other theory was that she was destroyed by a soviet torpedo.

That is all that was released or speculated on by MSM and those of us in the service. Being a sonarman myself, I always wondered about the acoustic data said. I was happy that it was finally released.

The two small internal explosions could have been anything, but certainly not a torpedo.

Good topic, i just done some searching around and it seems that a russian general who was the handler for john walker is unsure wether or not his information may have been used in the tracking and killing of the scorpion.

hamptonroads.com...

for a good first post! I remember the tense then sad times of the incident for the nation. This acoustic analysis provides answers for this tragic loss.

Personally, I never even wanted to go on the Disneyland submarine ride. I've enjoyed touring stationary subs, but no way would I be in one when the hatch closes! Hat off to you. The movie Das Boot has been a favorite; the scene where you could hear the creaking and popping is horrifically suspenseful.

The hot run was caused by a battery seal failure. Other hot runs for this torpedo type and battery date code were logged.

The torpedo battery was one of those that had the electrolyte sealed away from the plates. To spin up the torp, one of the steps involved breaking the seal and flooding the battery, powering the torpedo. If that happened accidentally, that is not in the normal spin-up procedure, the torpedo would skip the preliminaries like spinning up the gyros and receiving a course setting and go right to spinning the prop shaft as if it were in the water. If it "ran" long enough, it would arm.

A related problem was that the out-of-spec spin-up also meant that the torpedo gyros might not be at speed as in other "hot run" scenarios. That could prevent the 180 shutdown trick from working. Another issue was that when the battery activated this way, it got really hot. It's possible for the battery to cook off the torpedo charge even if the 180 trick was otherwise successful, although in this configuration it deflagrated instead of detonating, resulting in a fractional yield. This also goes along with what was recorded on the hydrophone logs.

The Navy caught on when several stored batteries self-activated in parts bays and burned up. Then some sub whose name I do not recall had a similar hot run with the torp on a maintenance rack, but for them the 180 maneuver worked and some quick-thinking seaman flooded the torp with water to cool it when he saw the paint burning off.

I certainly hope for that quick thinking seaman a medal of something or other should have been presented..

flooding a torpedo tube because he noticed paint burning off.. PHEW that must have been close.

b

reply to post by Bspiracy


Yeah, as I recall the problem was when they accidentally triggered, the battery was only partially flooded with electrolyte, so it had a relatively high impedance due to electrolyte starvation. The prop motor drew a really large amount of current, which caused the battery to heat, and the hotter it got, the higher the impedance went, but not enough to just stall out the motor.

In addition, the torp was undervolted due to the battery not working correctly, so you got a crap shoot as to what was working in the torpedo's systems, and whether or not it was working erratically. I'm not sure if that design carried a magnetic sensor to fire the warhead if it passed under a keel, but if it did, I'd have to bet there was some chance that would set the warhead off if the prop shaft spun long enough.

Originally posted by Submarines
- The initiating events responsible for the loss of SCORPION were two small explosions that occurred one-half second apart at 18:20:44Z on 22 May 1968 and were contained within the submarine’s pressure-hull. The source of these explosions, which are estimated to have been equal to the explosion of not more than 10 kg (22 lbs) of TNT each, cannot be determined from analysis of the acoustic data.

- These explosive events prevented the crew from maintaining depth control. SCORPION slowly sank to 1530-feet at which depth the pressure-hull and all internal bulkheads collapsed at 18:42:34Z on May 22, 1968 in one-tenth of a second with a force equal to the explosion of 6,000 kg (13,200 lbs) of TNT.

- This energy was produced by the essentially instantaneous conversion of potential energy in the form of 680 psi pressure on the entire SCORPION hull to kinetic energy, the motion of the intruding water-ram which entered the pressure-hull at supersonic velocity.

I think an explosion in the battery well caused the first two events.

I read Skipjacks were built with HY-80, the same as the LA class boat I served on. Was this class not equipped with an EMBT blow system ?

When the battery exploded, if it breached the pressure hull, seawater would hit the cells and generate chlorine gas. One of the scariest casualties you could face. The ship was unrecoverable that quickly. I think the newer subsafe boats are much safer and recoverable in the event of a major problem.

I read about someone crushed to death by one of the control surface hydraulic rams in an SSBN's shaft alley. Submarines, not the safest working environment.