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Old 06-24-2018, 06:57 AM   #1
Onkel Neal
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radar Russia's Alfa Class Was The Terrifying Hot Rod Sub Of The Cold War

One of the best articles I've read on the Alfa. This came out in 2014.



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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.

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.
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Old 06-24-2018, 07:05 AM   #2
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It was a big 'bulldog' at least.
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Old 06-24-2018, 08:06 AM   #3
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The Covert Shores website has a good article on the Alfa, which includes a nice cutaway diagram:
http://www.hisutton.com/Alfa_Class_Submarine.html




And an imgur album with lots of rare photographs:
https://imgur.com/a/WyJ20
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Old 06-25-2018, 02:59 PM   #4
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The 705's were ok submarines they had issues the 5 blade screw meant that the screw turned faster to produce more thrust the end result was increased noise, we know from Dr Ballard who worked with SOSUS and discovered the deep sound channel later on that an alfa coming off the north cape at 40 knots could be heard in Bermuda.

Yes their existence resulted in the development of ADCAP however their capabilities have been vastly over stated, as such some realities that have come to light in recent years regarding their design and role.

First off the hull cracking theory which is not true the boats themselves were rated down to only 450m the hype seems to have been bought on later in life by the hunt for red october which shows a fictional alfa class konavalov diving to 900m the truth is the alfa was a much more delicate submarine that we are told.

50 knot speeds again this has been debunked power to weight ratio's calculated by caltech in the late 1990's showed they needed a reactor with an output of around 65,000shp, the single OK550 / VMA40 lead bismuth reactor was unstable especially when running at high or low temperatures the latter resulting in the reactor going solid, on top of that when along side the reactor had to be kept switched on and heated to stop it from going solid this also happened while undergoing maintenance, this meant they were extremely expensive to maintain and operate and as we see now dispose of.

The alfa in practice could for short periods achieve 45 knots but could never sustain this and this is why the much larger and more powerful project 661 anchar (NATO Papa) currently holds the sustained underwater speed record of 44.7 knots again the lone 661 was built using titanium but like the alfa had a maximum operating depth of around 400-450m, this time the submarine was powered by two VM-5 PWR'S as opposed to the fancy lead bismuth design favored in the alfa.

The reason titanium was used for these submarines is because it is a lot lighter than steel it is also a lot stronger and crucially wont warp at high speed high pressure depths.

What we see later on with the development of titanium boats is the slower but more powerful (weapons wise) 945/945A Sierra class these boats are titanium hulled and they do dive very deep maximum operational depth is rated to 850m but they are not as fast as the papa or alfa mainly having a maximum speed of around 33 knots, these submarines look almost similar to the project 971 Schuchka Akula class, its worth noting that one of this class was involved in a collision with the USS Baton rouge the baton rouge suffered severe enough damage that the boat was scrapped while the sierra class Kastroma was repaired and put back in to service, sierra is likely to see a few more years service yet with 2 active and 2 awaiting or undergoing overhaul.

Probably the best titanium boat made for speed and diving capability would be Project 685 Plavnik Mike class which had an operational diving depth of 1020m you probably all know her as K278 Komsomolets speed estimates put her en par with the Sierra class 33 knots the early assumptions of her being powered by a pair of lead bismuth reactors were incorrect the soviet union did reveal that they were PWR's however a lot of the K278 aspects and data remain classified.
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Old 06-27-2018, 01:07 PM   #5
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What would we do without you Kapitan? It would be a lot less informative
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Old 06-27-2018, 01:25 PM   #6
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To be honest I wish that Alfas were made as super low noise subs vs super fast subs. But alas, noise reduction was not the prime consideration at the time.
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Old 06-27-2018, 02:28 PM   #7
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The walker scandal culminated in the termination of the Victor II (Project 671RT) at just 7 units it also highlighted to the Soviets that their submarines could be heard at distances beyond weapons range of their own submarines.

Alfa is no exception, on the edge of the rear hydroplanes you will find two outboard electric motors with twin screws these were used as creep motors, how successful they are we don't know but what we do know is nothing mechanical on alfa (like older boats and some newer ones) was rafted which meant noise emanated right through deck and hull then out into the water.

the Problems with a 5 blade screw means that the screw must turn faster to produce more forward propulsion for higher speed which has a down side it also creates low pressure on the tips of the blades which effectively boil the water and creates oxygen bubbles which burst this is what we call cavitation.

If you look at the 705's screw its much smaller than the later boats and western boats an example for size comparison the project 877 6 blade screw is roughly the same size yet the boat is much smaller in dimensions (but heavier due to steel construction)

You then see the adaption of a 7 scew blade propeller Le Redoubtable S611 by B S, on Flickr

The reason for this is simple the large diameter propeller turns slower but produces as much thrust it also cuts down on the low pressure by turning slower and at higher speed the shape negates the low pressure and dissipates the oxygen bubbles more effectively so you thereby have a submarine that can travel faster quieter with less revolutions of the propeller.

It is also worth noting that the bubbles of oxygen that explode on the propellers surface causes dimples on the blades and cuts & dents on the leading edges which means the propeller isn't as efficient as it should be and as the surface is not smooth it can create more noise.

This can be detected by a good sonar operator !

Counter rotating screws were trialed on the Project 671 RTMK Victor III with limited success notably they were not fitted to the Schuchka Project 971 Akula or later boats.

It appears a new way forward is Pump-jet propulsion basically a slow spinning turbine or screw with multiple blades like a jet front fan which sucks in water forward and ejects water out a smaller channel aft this has been favored by the USA UK and Russia in recent times we do know the Seawolf Virginia Trafalgar Astute Yasen Borei & also a project 877V kilo are fitted with these.

While Russian in terms of computer technology lags a little behind the west they are advanced in other ways SOKS is a real device and has been mounted on many vessels in fact a project 627A November class trailer an american Boomer out of Rota Spain in the 1980's using the system, Russia has also heavily invested in upgrading and replacing sonar systems in older boats.
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Old 06-28-2018, 01:43 AM   #8
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Alfa had equipment on shock absorbers. The issue was the requirements, the requirements (TTTs) were changed and resulted in Victor-II, you can really see it in the "рекомендации к проектированию подводной лодки в малошумном исполнении" (1971) and ВАХ-68->ВАХ-74 requirements for onboard equipment.


So the long term shift (and such studies as project 991 that resulted in Akulas) well predate the walker scandal.
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Last edited by ikalugin; 06-28-2018 at 02:16 AM.
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