Search This Blog

Wednesday, February 05, 2014

K-278 Komsomolets (Project 685 Плавник), Mike Class

K-278 was a unique and magnificent submarine.  Only one of this class of ship was built.  Because she was so unusual, construction took an unusually long 5 years.  Her construction began in April 1978, she was launched in May 1983, and commissioned on the last day of 1984.  The Soviet Navy rarely named their submarines, but this ship was special, and received the name of "Komsomolets" - which means "a member of the Young Communist League".

Komsomolets was to the Soviet Navy what the USS Thresher was to the US Navy.  She was a fourth-generation nuclear ship, a platform for testing a host of very advanced features. 

Komsomolets was a typical Soviet design with a tough inner hull and a thin outer hull.  However her inner hull was made from titanium alloy.   Welding titanium is notoriously difficult - even the tiniest amount of oxygen will ruin the weld.   To assemble this ship, a special airtight building was constructed, and then filled with argon gas.   Shipyard workers in forced air breathing suits would enter the building, and assemble and weld the titanium alloy plates of the inner hull together, in complete absence of oxygen.

In August 1984 Komsomolets dove to a record depth for a warship of 3350ft, a testament to the engineers who designed her, the welders who built her, and the men who put their lives on the line in this impressive prototype.  This depth is significantly deeper than any US military submarine can go, and far deeper than the US MK-48 torpedo could operate at that time.

K-278 was equipped with seven watertight compartments.  The compartments closest to the sail were toughened even further against internal flooding.  She was equipped with an escape pod at the rear of the sail that would hold crewmembers, and could be released from the ship in the event of disaster.  She was highly automated, and operated with about half the crew that similar ships would carry.

In a break with the past, Komsomolets used a single PWR of 190MW and what appear to be dual counter-rotating screws for propulsion.  It had been suspected that this ship would use dual liquid metal reactors for higher speed, but the Soviets were apparently becoming more interested in stealth than raw power and speed.

She was one of the better-looking Soviet submarines, capable of carrying a mix of torpedoes and cruise missiles with conventional or nuclear warheads

Profile of K-278.

Image of K-278 underway.

In April 1989, after four years of shake-downs to test her automatic systems, weapons systems, and pressure hull, Komsomolets went on her first actual patrol.  It ended tragically. 

K-278 was the deepest-diving military submarine ever built.  At her maximum operating depth, the surrounding seawater pressure would be about 1500 psi.   The High Pressure Air Banks would have to contain several times that pressure, because an Emergency Main Ballast Tank Blow must *rapidly* displace the water in the ballast tanks.

Greater air pressure allows the ship to get positive buoyancy faster, which under flooding conditions means greater survival odds for the ship.  Komsomolets was so deep-diving that her high pressure air banks must have contained phenomenal pressure.  An educated guess about the operating pressure of her air banks is 8000 psig, and that could very easily be on on the low side.

On April 7, 1989 a high pressure air line that led from a high pressure air bank to the main ballast tanks through the engine room ruptured on K-278.  Sheared off pipes containing gas such pressure can bend and whip like noodles due to the force of air jetting out of them.  In this case, the sheared off pipe damaged an oil system, which in turn leaked oil on a hot steam turbine.  A flash fire broke out, fanned by the still-leaking (and probably deafening) high pressure air.  The ship was running at a depth of 1100 feet.

The control room noticed an increase in the temperature of the engine room, and called back to ask about the trouble.  there was no answer.  They delayed activating the Freon fire supression system, knowing that Freon would suffocate everyone in the engine room, but eventually they activated it.   Unknown to the control room, the Freon was ineffective at smothering the fire due to the massive inflow of air from the high pressure air bank. 

Although the watertight doors were shut and ventilation isolated immediately when the casualty started, the fire spread to other compartments.  The engine room, which was engulfed in flames, was also pressurized by air blasting from the ruptured air pipe.  This pressure pushed flames into other compartments via cable penetrations.

The ship begam to die.  The reactor scrammed (tripped), so the turbine generators soon lost steam pressure and also tripped.  This caused a loss of most electrical power.  The main propulsion turbines also stopped turning as steam pressure faded.  Hydraulic pumps that were powered by the turbine generators, and which activate the rudder and planes, also lost power.  As the hydraulic pressure bled down, the ship's rudder drifted stuck, in the down direction.  The depth of the ship was now 500 feet. 

An emergency main ballast tank blow brought the ship to the surface.  For several hours, most of the crew was topside, except for those involved in fighting the casualty.  The temperature in the engine room eventually reached 2000 F, and melted through a pipe or some other system that prevented seawater from entering the ship. 

Shortly after surfacing, the ship sank in rough water, with the surviving crew abandoning ship.  The captain and four other officers who had remained on board as the submarine sank entered the escape capsule and ejected.  Apparently as the submarine sank with the hull compromised, air pressure built up inside the ship.  When the five entered the escape capsule, the air pressure was much higher than normal.  When they opened the hatch of the escape capsule after surfacing, there was an explosive decompression that killed two of them and knocked two others unconscious.  Only one of the five managed to exit the escape capsule after it reached the surface, before it also flooded and sank. 

A Soviet floating fish factory arrived on site just 81 minutes after K-278 sunk.  By this time 5 men had already died from hypothermia.  25 men were rescued and survived, but 42 others are on Eternal Patrol in K-278.

K-278 Komsomolets, a very unique and impressive ship, lies in 5500 feet of water, carrying two nuclear-tipped torpedoes.  Traces of plutonium have shown up near the wreck, and this is of great concern, because it is a rich fishing area.  In the future K-278 may be raised to remove her radioactive materials from such an important source of food.

No comments: