GepardThe problem isn’t just age which means an extensive and expensive reconditioning of the ship but also aircraft complement. In theory they could be useful as JSF carriers but most nations planning on fielding such a capability are building their own light carriers / landing ships. I suspect the Royal Navy would want to keep them but with all their costcutting reviews its unlikely. Remember they decommissioned state of the art Upholders to save a few pennies, likewise with Sea Harrier. Its a good question though.
GepardThankyou very much OMSSMretd, its always a pleasure to hear from a profesional on such matters. Six years working on Type 2007 / 2072. Wow! As someone who should have joined the Navy, I have always been fascinated by these underwater battleships but public literiture is somewhat contradictory. Iam surprised Clancy got it wrong but there are plenty of forumers who would say its not the first time. I always thought the array ran down either side fwd of casing air vent. Its logical especially looking at older photographs. It’s good to have professional confirmation of the fact. One last question, the damaged bow of Trafalgar and the bow of Triumph: Are the bow sonar dome casings the same in shape or is there a difference between type 2074 and type 2020. I suspect differences are under the dome. Please advise if you can.
GepardWell Sierra II has trim tabs on bow planes. The absense of large hatches near the bow planes on the 971 class suggest they retract straight in. No pictures sorry, others might have them on this forum.
GepardThat makes more sense. John Jordan’s book, Soviet Submarines, 1945 to the present suugests they were CCTV camera but ice guards is a more likely answer.
GepardI know, but there were 80s technology!
GepardTurbo electric drive is slower. The Americans experimented with it with Tubilee in the 60s and later Glenard P Lipscomb in the early 70s but the speed penalty always ruled it out. The French never had the speed requirements of the U.S, hence turbo electric drive was a technologically much easier way to achieve quietness and with SSBNs in particular speed was not much of an issue. Remember even the Ohio was not designed for speed, hence the use of a natural circulation reactor in its design. Remember this was the Cold War and U.S Submarines had become slower and slower to obtain quieting from Skipjack to Permit to Sturgeon which could make roughly only 26 knots. When Rickover killed Conform, one of the reasons he cited was the need for high operational speeds to escort carriers. Turbo electric drive was clearly incompatable with the speed requirement of Los Angeles and later developments like natural circulation, or the ability for a reactor to circulate coolant without pumps at low speeds using convection (available at low speeds on Trafalgar, Los Angeles, Akula, Sierra), meant you could have silence at low speed and high speed when you needed it which was operationally more desired than covertness at the cost of high speed capability. Natural circulation clearly held much promise to the Americans which was later vindicated in the all natural circulation reactor of the Ohio, its use in Los Angeles to allow very quiet, sprint, drift operations and of course Seawolf which boasted the previously low speed natural circulation range to over 20 knots. Additionally though turboelectric drive reduced noise of gearing, improvements in manufacturing tolerances meant gear teeth could be made finer and with it, the noise of gearing much reduced so the appeal of turbo electric (remove loud gearing) became much reduced. By way of example, the Soviets estimated that the Delta IV could not match Ohio in covertness largely because they could not making gearing to such fine tolerances as the Americans. So the path to quietness could be reached without the speed penalty by a combination of natural circulation, better gearing tolerances, rafting improvements (double rafting in Seawolf, Akula), better and quieter coolant circulation pumps when at high speed and later tiles. Remember this was era of the high speed Alfa, Sierra and Mike threats. Now, of course natural circulation is available up to 20/ 25 knots (Seawolf tactical speed) and pumps are much quieter (big improvements were made with 688 Improved class) so you can have speed without the speed loss of turbo electric drive.
GepardNo picture but Iam sure someone else will post one but here is a brief explanation. The slower a propeller rotates the less caviation (noise) it makes. This has led to large multiblade propellers like on the Ohio that move very slowly but still provide adequate propulsive force. As an anecdote amongst the improvements made to the 636 Improved Kilo to quieten it is a 50 percent reduction in rotation speed of the propeller to reduce cavitation and rotation noises. This gives you some idea how important a source of sound, propellers can be. Additionally propeller tonals are a major low frequency (long range) means of identifying and detecting submarines. The Pumpjet takes the idea of a large slow turning multiblade propeller one step further. Instead of a large slow propeller what if you could put the propller in a shroud so it could move slower and quieter still? By having a shroud you prevent water being pushed sideways by propeller so you can move propeller slower. Additionally the shroud acts as a side wall to noise emanating sideways from propeller. Sound is now in theory restricted to very specific directions of dead aft in a cone and just ahead of pumpjet but shrouded by the submarine hull itself. Now if you add multiple rotors (blades) and add stators (fixed blades like on jet engines to straighten out centrifuegal flow from rotors) you can have a very quiet propeller with many, many blades (up to 10, 15 on Trafalger class) that moves much slower than a conventional propeller and which is also quieter since shroud can mask noise of rotors turning as well. As an example of its effectiveness, the Trafalgar class can reportedly move from 5-15 knots with NO vibration.
Operationally this adds up to higher speeds whilst remaining covert and not cavitating. Additionally this means a higher tactical speed (speed at which you are covert but still able to use sonar). The only barrier to high tactical speeds once you have a pumpjet is adequate machinery quieting (double rafting like Akula / Seawolf), adequate flow noise coatings and good hydrodynamic design to reduce onset of flow noise from high speeds which result in washout (speed where flownoise blinds sonar), and to reduce large increases in broadband noise levels from flow noise.
Seawolf which was designed to fight it out in the bloodfest that would be a Barents Sea bastion battle (as part of the U.S navy’s Maritime Strategy) was designed with a Pumpjet to confer it the ability to fight, detect and escape datums at high tactical speeds which individual Soviet units would not be able to match (a platform going faster than Seawolf or equal in speed would not be covert nor be able to use its sonar to detect Seawolf which itself would be covert and be fully able to see around itself with sonar maintaining a hopefully decisive advantahge in situational awareness). The concept is to fight faster than the enemy, similar to the supercruising concept of the ATF whereby soviet fighters could not be able to fight at the speeds ATF could and be robbed of the initiative since they could not engage or disengage at the time of their choosing. Thus pumpjets are invaluable for helping to raise tactical speeds of submarines.
The disadvantage is weight from the shroud, cost of design which can be challenging and until recently with the British, erosion of the pumpjet shroud which is now composite on the new Astutes to reduce this and its associated maintenance cost.
GepardAccording to Tom Clancy’s book on Submarines in which a tour is made of Triumph, the 2072 is a new array, the dark, long semi-cylindrical bulge running alongside of the picture above. Does anyone know if this is correct or indeed what this bulge ids given that tiles are clearly affixed to rest of the hull?
GepardTrident, the triangular objects on the Akula (Typhoon) stern are CCTV (closed circuit television) cameras. They are there supposedly to assist in under-ice maneouvering and breaking through ice but most importantly are there to monitor the release and retrieval of the VLF buoys deployed from 2 hatches just ahead of the cameras. The Delta IV has a similar retractable CCTV camera for the same reason. Given that SSBNs are priority strategic platforms, communication is an absolute neccessity, thus the ability to establish if the VLF buoy is operational or not is the reason these devices exist. Interestingly they are not present on Akula, Sierras and Oscar IIs which have the VLF buoys but then again they are not strategic assets where not knowing about VLF reception failure is unacceptable.
GepardSo is this an Akula 2 and if Gepard is a development of Vepr, Akula 2 with just a longer sail and towed array does that mean they are both the same length (Gepard is officially 113m lond , beam 13.8 )http://www.cdi.org/russia/johnson/5581-5.cfm
Now standard Akula is said to be roughly 110m long beam 13.6 (these figures it vary).
So is Akula 2/ Gepard longer than standard Akula by the same length?
GepardWhen was that book published and what is its full name and how can one purchase it?
GepardWhat is that book called and who is the author, how can one purchase it? When was it published? I know its alot to ask but the book seems fascinating.
GepardThe reason these runs are reduced can be answered in one word: POLITICS.
Often especially in economic downturns, no one (ie politicians) likes to sign off on billion dollar weapon systems. Its much easier to say “surely we can scrap this monster and develop something smaller, cheaper and better with newer technolgy”. Its an appealing argument to the layman but as everyone on this forum knows cuts in cost come at capability and when said cheaper system has been approved in its reduced capability form, just watch the add ons to the design. This is how JSF (remember no radar, tamper proof technologies), F22 (affordable stealth) and almost all weapon systems are sold. Remember the cheaper Arleigh Burkes? Not really once you add the enclosed flighdeck etc. Astute also comes to mind as an example of deliberately selling a design at a cost thats probably not realistic but will get the project approved…
GepardI agree. For a socalled spherical sonar the torpedo tubes should be angled out like thes models of the Grany / severodvinsk…
GepardDeepstorm info on Sierra 3.
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