Developed in the ‘60s at the height of the Cold War, it remains the fastest of its kind till this very day. Its propulsion system was so powerful that it required an overhaul after a single high-speed mission. It could operate at unrivaled elevations, was ridiculously expensive to operate and its very existence sent the US into a frenzy trying to counter it.

This may perfectly describe the famously brutish MiG-25 Foxbat, but it also describes another Soviet technological marvel of the time period, the more obscure but arguably more impressive Alfa Class interceptor super-submarine.

From the day of its inception, the top secret Project 705, also know as the Lyra Class in Russia, was designed to be extremely fast and maneuverable. As a result, it drastically pioneered many technological frontiers to get there.



The idea behind Project 705 was that a very fast hunter-killer sub could chase down any surface combatant while also being able to evade almost all anti-submarine weapons fielded by NATO at the time. Although immense speed was the project’s primary design goal, the sub also had to be hard to detect while running at lower speeds, especially via active sonar and magnetic anomaly detectors.

Because the project’s main design goal, to reach speeds of over 40 knots submerged, was so ambitious, a tighter, smaller hull form was required to achieve it. This small size, displacing only 3,200 tons submerged (as opposed to more than double that for the Victor Class of similar vintage), meant that the crew size had to be dramatically decreased, thus very innovative automation would have to be developed to allow a crew of 31 to do the job that a crew of double, triple, or even quadruple the size would normally be tasked with. Because of these crew size restraints, the Alfas were to be manned by an all officer and warrant officer complement, plucked from the cream of the Russian Navy.

As a result of the small crew and their limited access to sensitive components, no maintenance was to be performed while at sea beyond emergency repairs and the whole boat was ran from a single control room with just eight officers on watch. During tests, the Soviet Navy found that having such a small watch crew all huddled together largely in one room, greatly decreased the reaction time during combat maneuvers. This snappier decision making resulted in enhanced combat effectiveness was a well-matched feature for the Alfa Class’s blistering performance.

The Alfa Class had a double hull design, with the inner hull handling the enormous pressures that would be faced by the sub’s extreme operating depths (stated at over 2200 feet, with some sources putting its crush-depth at over 3600 feet!), and a lighter outer hull that is optimized for speed, maneuverability and acoustic stealth. For its high strength and low weight, the Alfa’s hulls were made out of massive amounts of titanium.


Because titanium was still an exotic metal at the time (the A-12 and SR-71 were groundbreaking in the west for their wide use of the metal, which was bought through a fake shell company from Russia), it is said the US was in doubt that it would be used for this new class. Nearly a decade passed between the class’s first test runs and confirmation of the hull metallurgy by western intelligence agencies. It is rumored that titanium shavings from the floor at a St. Petersburg shipyard, where the Alfa Class subs were built, were smuggled out of the country via espionage, thus proving that titanium was indeed the metal that was being used largely in this high-speed class’s construction.

None-the-less, shaping and welding huge pieces of titanium for the sub’s hull was said to have been a major challenge, and some reports say that the entire construction shed where the Alfa boats were built was filled with inert argon gas and the builders had to put on moon suits while welding her light-weight but super-strong hull together.

The submarine’s inner pressure hull was separated into six main compartments, of which only one was habitable for the crew’s for daily use, the rest being packed with weapons, sensors, nuclear propulsion and other machinery. Although this greatly hampered livability aboard the relatively small, 267 foot nuclear submarine, it allowed the command and living section to be a pressure vessel unto itself, which would have greatly increased the crew’s survivability if they were struck by an enemy torpedo or depth charge during combat. The Alfas were also unique in that they had a crew escape module that could take all the crew safely to the surface should the ship be catastrophically damaged. This was said to have been a result of the horrific events surrounding the K-19 incident.


The most outrageous aspect of the Alfa Class design was its exotic nuclear reactor, which was a compact and incredibly powerful unit that was cooled by molten metal (lead-bismuth). The advantages to such a reactor setup are numerous include greater efficiency and being less prone to leakage, but the disadvantages were also quite severe, which you can read about here.

One of the most prominent disadvantages of the Alfa Class’s lead-bismuth nuclear reactor setup was that it could not be shut down unless a source of super-heated off-board steam was available to keep the molten lead-bismuth coolant in a non-solid state. If it were allowed to solidify, which happened at 257' F, the reactor would be unable to be restarted as its fuel rods would be frozen in the solidified metal coolant. Similar to a fire that constantly needs to be fed or you literally have to build a new one from scratch, the Alfa Class’s nuclear reactors were innovative but extremely demanding.

Seeing as the USSR’s port-side infrastructure was more of an afterthought compared to the high-tech submarines and ships that relied on it, often times an external steady steam supply was less than reliable. Thus the subs would have to run their reactors continuously while in port to maintain their coolant in a liquefied state. Such a situation meant that the ability to do deep maintenance on the reactors was a challenge and they were never really built to be ran continuously for extreme periods of time in the first place. Thus their lifespan was greatly reduced, and it is said that four of the seven Alfa Class submarines met their retirement early due to entombed, or ‘frozen’ reactors cores that could not maintain their coolant’s high temperature needs.

The Alfa’s cutting-edge and sometimes less than reliable automated systems, small crews, and their needy reactors, kept them in port much more than their traditionally configured, nuclear hunter-killer submarine cousins. Thus, like their MiG-25 analogues, the Alfa Class boats were used as alert interceptors instead of on long escort screening missions or patrol duties. They would wait in port until a target was detected, at which time they would scramble out of their harbor and sprint to that target’s last known location. There they would begin their cat and mouse game, and this was a game they were incredibly good at.


These ‘interceptor subs’ had a single five bladed main screw tied to a 40,000hp steam turbine that could blast the boat through the depths at unprecedented speeds. The Alfa Class was also equipped with two additional smaller and super-quiet, 100kw, electrically powered propulsors, that were used for stealth maneuvering. Different sources state different speeds that the Alfa Class boats were capable of hitting, but largely their top speed was said to be in excess of 43kts. Some have even said these boats were clocked doing over 50kts while running from an armada of American anti-submarine assets. Keep in mind that the American Los Angeles Class SSNs, many of which are still in service with the USN today, are said to have a top speed of around 35kts and a dive capability stated as 950 feet. Really, this number is said to be closer to 1250 feet, with a crush-depth of 1500, which is not even close to the Alfa’s low-ball estimated maximum operating depth of just over 2200 feet.

The Alfa boats were not just ridiculously fast and deep diving, but they were also super maneuverable, and said to be able to accelerate at a blistering rate (some reports say they could go from a dead stop to full speed in under two minutes, while others put it at just under 90 seconds). There small size and light weight meant that they could also come to a dead stop on a dime while changing depth and course rapidly via her gobs of excess power. All these qualities, along with her stealthy shape and skin coatings, put the Alfas outside the engagement envelope of the majority of anti-sub weaponry fielded at the time of her lead ship’s commissioning.


According to a Navy anti-submarine officer that served during the days when the Alfa Class was not yet fully understood and highly-feared on — or below — the seas, these boats were “loud as hell” when speeding toward their targets or muscling around during tight maneuvers, but once when they were operating on their propulsors, they were as quiet as any Russian hunter-killer sub deployed at the time. Additionally, the Alfa’s ability to rapidly dive so deep, well below the thermocline, gave them an ability to disappear and reappear over fairly large distances in a relatively short period of time.

The Alfa Class was not a particularly heavily armed attack submarine, being able to carry 18 torpedoes. But this arsenal could include the 250mph, supercavitating, rocket assisted VA-111 Shkval, which could put a western attack sub on the defensive in seconds. All things considered, the Alfa Class’s limited magazine was fine considering that these boats ended up being interceptors as opposed to true long-range hunter-killer subs. As for the Alfa Class’s ability to detect enemy submarines and ships, the sonar systems installed were state-of-the-art, and highly capable, but their high degree of automation and smaller size meant resulted in them being temperamental. This, combined with these boats’ small crew meant that sensor system failures, even relatively rudimentary ones, could result in mission kill.


In the end a total of just seven Alfa Class subs were built, many less than the USSR led on to be in the works, and the first in the class, The Leningrad, was more of a prototype than an operational boat, as it suffered from major defects with its titanium hull and higher maintenance reactor design than follow-on production units. Still, these boats, and their highly secretive development cycle, set off a scramble in the west that resulted in new torpedo designs, mainly the US Mk48 ADCAP program and the UK’s Spearfish torpedo program, improved detection systems, all of which were needed to detect and mitigate the Alfa’s raw performance edge. Additionally, the fear that the Soviets would build up their fleet with many dozens of these small, high-speed subs spurred further investment in US and its allies’ naval anti-submarine capabilities.

As the late 1970s turned into the early 1980s, like its high and fast flying MiG-25 counterpart, the threat posed by a small force of Alfa Class subs was realized to be more terrifying on paper than it was in real life. Yet some naval historians state that the Alfa Class, even with its noisy emissions during its high-speed runs, could have been paired with super-quiet and slower attack subs to devastating effects and that the Class’s biggest missed opportunity was how it was implemented, regardless of how reliable and expensive they were to operate.

On the Russian side of the Alfa Class’s legacy equation, evolved versions of many of the boat’s innovative automated systems and structural design elements were carried over onto the highly successful Akula Class hunter-killer sub series, which still serves with the Russian and Indian Navies today.


By 1995 all of the charismatic but very expensive to operate (they didn’t get the nickname “Golden Fish” for nothing) and temperamental Alfa Class boats were either decommissioned or previously written off. Since their heyday, submarine design has concentrated much less of brute speed and deep operating depths and more on stealth, persistence and affordability, both in terms of life-cycle costs and acquisition costs. Still, just as with its equally operationally unbalanced, high and super-fast flying MiG-25 cousin, the Alfas will be remembered as the shadowy hot rod subs of the Cold War. Thoroughbred boats that may have had their clear deficiencies, but that pushed the technological barrier to the edge of collapse and back again during their relatively short operational lives.

Pictures via public domain. Sources, Military-Today


Tyler Rogoway is a defense journalist and photographer that maintains the website Foxtrot Alpha for You can reach Tyler with story ideas or direct comments regarding this or any other defense topic via the email address