by James Jinks
A number of different designs were produced. The first was Design A1, a submarine 62 metres in length and 7.3 metres in diameter, with a submerged displacement of 1960 tons. Design B1 was a slightly larger submarine, 67 metres in length and 7.6 metres in diameter, with a submerged displacement of 2250 tons. Design D1 was even bigger, 75 metres, with a hull diameter of 7.6 metres and an overall displacement of 2650 tons. It quickly became clear that available design resources, both for the submarine and for its weapons systems only permitted further detailed study of one of the options. Design A1 was quickly discarded, and discussion centred on B1 and D1. While B1 was the preferred design of the Naval Staff, Vickers preferred D1 and its greater range and weapons load capacity because it had ambitions to market the new SSK design overseas and believed potential customers would be interested in larger ocean-going SSKs. However, D1 was definitely too big for the Navy’s operational requirements, and it would have proved too expensive to maintain the cost-effectiveness argument against the SSN.61
As a compromise solution between the Navy’s operational requirements and the demands of the export market, the Director General Ships proposed a B1-based design, with a slightly rearranged internal layout and an increased submerged displacement of 2400 tonnes. This would allow the submarine to carry sufficient fuel for a patrol range of 24,000 miles and twenty-eight days on station. The design could also be stretched to include more fuel if some customers considered this necessary, and an even greater weapon load.62 This was considered acceptable by Defence Sales, British Shipbuilders and the Royal Navy, which accepted a small number of minor penalties, such as reduced maximum dived speed and reduced submerged endurance. The final design, known as the Vickers Type 2400, represented a significant increase in capability over the designs of the 1950s ‘Porpoise’ and ‘Oberon’ classes. The hull design, machinery mounting and hull coatings all benefited from three generations of SSN design. The result was an SSK that promised a more up-to-date weapon fit, greater endurance and quietness, and a complement of 47 compared with the 69 in the ‘Oberon’ class. It was also anticipated that maintenance and refit times would be reduced by 20 per cent.63
With a submerged displacement of 2465 tonnes and a surface displacement in diving trim of 2205 tonnes, the pressure hull of the submarine was constructed using high-tensile steel, with high-tensile steel frames, and extensive use was made of glass-reinforced plastic in the casing and bridge fin. The class had a deep-diving depth of 250 metres. Its single propeller, of an advanced noise-reduced design, allowed it to travel at speeds of 20 knots dived and 12 knots surfaced, with a range of some 8000 miles. Course and depth were controlled using an advanced new autopilot. It was also equipped with the French bow passive, intercept and active sonar ‘Triton’ which was branded Sonar 2040 in the Royal Navy. The first of class, HMS Upholder, was fitted with a Sonar 2026 towed-array system, while later submarines featured the more advanced and cheaper 2046.64 Because it would not have an anti-ship role, the new SSK would only carry wire-guided torpedoes, such as the Mark 24 Tigerfish, usually only fired singly or in pairs, allowing a reduced weapon load.65
To ensure that the required minimum of submarine hulls was maintained as the ‘Oberon’ class reached the end of their service lives, it was decided that the first of the ‘Upholder’ class should be in service by 1986. A Project Order contract was placed with Vickers in 1980 and a significant percentage of the Vickers design and drawing office staff were engaged on the project, for which a one-fifth scale model and part mock-up were produced. HMS Upholder was laid down in 1983 and launched in 1986, while three more of the class, HMS Unseen, HMS Ursula and HMS Unicorn, were laid down at Cammell Laird (which had by then been purchased by Vickers Shipbuilding and Engineering Ltd) in 1986. HMS Upholder was meant to commission into the Royal Navy in 1988, but there were delays and increased costs, and the submarine was only delivered in June 1990.66 HMS Unseen followed in June 1991, HMS Ursula in May 1992 and HMS Unicorn in June 1993.
THE ‘TRAFALGAR’ CLASS
The Royal Navy’s twelfth SSN, HMS Splendid, the last of the ‘Swiftsure’ class, was commissioned into the Royal Navy in March 1981. Development work on the next class of Royal Navy SSN had started as far back as 1968 under the codename SSN0Y when Rolls-Royce and Associates began development work on a new SSN primary plant, with increased core life and reductions in the pumping power and noise of the main coolant pumps. Work on the design of a new, longer lasting core, known as Core Z, was completed in 1971 and a prototype was fitted at Dounreay in 1973/74. This new design significantly reduced the low-frequency radiated noise and self-noise of the plant and offered an extended operating life over that of Core B used in previous SSN/SSBN classes. The new core was installed in most of the ‘Trafalgar’ class submarines, and retrofitted to the ‘Swiftsure’ class.67
As in the ‘Swiftsure’ class, the ‘Trafalgar’ class was fitted with five forward torpedo tubes, all capable of accepting the Mark 24 torpedo, and RN Sub Harpoon. Twenty weapons stowage positions were fitted and salvo firing capability was improved. These adjustments resulted in a small increase in both the weight and space demands of the design and it was necessary to lengthen the ‘Trafalgar’ design by several frame spaces. The ‘Trafalgar’ class thus had a submerged displacement of 5210 tonnes and a deep surface displacement of 4740 tonnes, and a speed reduction of around 1 knot compared with the ‘Swiftsure’ class. The overall length was 85.4 metres and the pressure hull diameter of 9.83 metres was the same as the ‘Swiftsure’ class. Deep-diving depth also remained the same, at 381 metres, and in spite of the increase in length the maximum submerged speed of the class was nominally 29 knots with a maximum surface speed of 12 knots – again similar to the ‘Swiftsure’ class. The first of class, HMS Trafalgar, was fitted with a seven-bladed Skew propeller, but subsequent submarines were fitted with a new Pre-Swirl Pump Jet (PSPJ). The PSPJ was designed to decrease the range of detection from blade noise and to permit the replacement of individual blades.
The ‘Trafalgar’ class was also designed to meet lower noise-level targets in order to reduce detection risk and interference with on board sonar systems. The class was fitted with the latest technology including principal hull-mounted active/passive sonar known as sonar Type 2020, to replace the 1950s-era Type 2001. Based on more modern technology, most notably computer processing, Type 2020 provided improvements in range, accuracy and target handling ability and gave submarines an improved capability to identify and track several ships and submarines simultaneously. It could also obtain fire control solutions earlier, allowing the class to use its weapons to greater advantage.68 From 1983, the ‘Trafalgar’ class was also fitted with the latest towed-array system, an all UK equipment to replace the less capable US/UK sonar 2024, which had been installed on thirteen SSNs and four SSBNs. As well as exploiting advances in towed-array/processing technology, the new sonar suite Type 2026 was specifically designed to match UK submarine command and control arrangements.69 It also had a great deal of ‘stretch potential’ – its capacity to adapt to future threat changes – and the Navy anticipated that alterations to its software would maintain its in-service life until the end of the twentieth century.70 The ‘Trafalgar’ class was also fitted with Type 2007, a long-range passive flank array; Type 2019, an intercept, forecasting array, as well as other types.
The Project Order contract for the ‘Trafalgar’ class submarines was placed with Vickers in April 1972, with the first of class, HMS Trafalgar, due on 7 September 1977. A shortage of Grade ‘A’ Welders and a thirteen-week industrial dispute at Vickers meant that it was not launched until July 1981.71 Commander Martin Macpherson took HMS Trafalgar out of the Vickers building yard and was immediately impressed by its capabilities. ‘I suppose the thing I remember most, being most confident about, was how quiet she was,’ he said. ‘Unbelievably quiet, which gave you huge confidence in terms of operating against the Soviets.’72 During trials to test for underwater noise transmissions, US sound engineers on board
a US monitoring vessel reportedly asked Macpherson when he would be starting his run past the monitoring ship, to which the CO replied: ‘We have just completed it.’ As well as being exceptionally quiet, the ‘Trafalgar’ class were also fast.73 ‘You could run at maximum power about 27 or 28 knots in Trafalgar with a pencil standing on the desk and it wouldn’t fall over,’ recalls Macpherson. ‘You go maximum speed in Valiant and you really know it. It’s like driving an MG TC [a classic car produced in the 1940s] over a bumpy road. In Trafalgar it’s absolutely smooth.’74 HMS Trafalgar was followed by six other submarines of the same class: HMS Turbulent in April 1984; HMS Tireless in October 1985; HMS Torbay in February 1987; HMS Trenchant in January 1989; HMS Talent in May 1990; and HMS Triumph in October 1991.
SSN0Z AND THE FOLLOW-ON SSN
The Nott Review (see here) also influenced the Navy’s plans for the successor to the ‘Trafalgar’ class. The main offensive and deterrent tasks that were anticipated for the SSNs by the end of the twentieth century had important implications for the construction of the Navy’s SSN fleet. Whereas in the past it had always been held that quality in SSNs was paramount, the projected burden devolving on future SSNs shifted the balance towards quantity. The Royal Navy had intended to follow the US Navy, which had started to develop a brand-new class of highly capable submarine known as the ‘Seawolf’ class. A revolutionary new submarine would break the evolutionary philosophy that designers had followed since Dreadnought first went to sea in the 1960s. Studies were first put in hand in 1969 to establish the kind of attack submarine the Royal Navy would require beyond the 1980s. An Outline Staff Target (OST 7052) for an entirely new design, known as SSN0Z, was endorsed in May 1978. But to meet the Naval Staff Target, the Fleet Requirements Committee required further studies into another five options with reduced costs. These studies reported at the same time as the Thatcher Government embarked on the Trident programme. All work on SSN0Z ceased in the autumn of 1980 when work on the SSBN successor absorbed the available resources.
SSN0Z aimed to achieve improvements in every operational aspect of SSN performance, an increase in speed, diving depth and firepower, propelled by the new PWR2 nuclear reactor designed for the ‘Vanguard’ class SSBNs, and equipped with an integrated sonar system, and a more capable combat system.75 This resulted in numerous designs ranging from 6500 to 7300 tonnes with an average cost increase of 38 per cent compared to that of the Trafalgar design. As Rear Admiral Marsh, Assistant Chief of the Naval Staff (Operational Requirements), pointed out, ‘in the face of insistence on maintaining the greatest capability in all areas, the design had become large and expensive’. The Navy attempted ‘to trim the design to bring down costs but it had proved generally insensitive to cost-cutting attempts.’ The design became ‘over-ambitious’ and the Navy, faced with a realistic view of the country’s economic position and its effect on resources available for SSN procurement, concluded that ‘it would have been difficult to argue such a costly weapons platform through Committees’.76 The design was shelved and further work effectively postponed.
Not everyone was happy with the demise of SSN0Z. During a meeting of the Fleet Requirements Committee, it was pointed out that:
Work on the SSN0Z design had been properly carried out on the basis of threat assessments and should not therefore be lightly dismissed. It would be more appropriate for the design to be suspended pending the outcome of the further studies rather than abandoned completely; this would allow future judgments to be made on the complete range of options available.77
Indeed, Rear Admiral Anthony Whetstone, Assistant Chief of the Naval Staff (Operations), who was on leave when the paper went to the Fleet Requirements Committee, observed that:
the aim of the SSN0Z design study was not to produce a submarine costing 38 per cent more than SSN0Y [the ‘Trafalgar’ class] but to ensure that our SSNs (which must inevitably number less than the Soviets) maintained superiority of quality. Unless the studies were dishonest or incompetent the 38 per cent cost increase was considered to meet this aim.
If we design down to SSN0Y + 10% cost what guarantee have we that the operational capability will meet the requirement? A submarine that will encounter its Soviet opponent at an inherent disadvantage must be of questionable value. Having two or three more won’t affect the issue as (1) submarine encounters are almost invariably one against one and (2) losing ten encounters is no better than losing eight.
Therefore if we are to keep an SSN force at all, its members must be designed to out-detect and out-fight the Soviets. Whether they need also out-run, out-dive and out-communicate is perhaps open to argument.
The conclusion I draw from the above is that in the SSN case we should design up to operational requirement not down to cost. If savings are needed they should be made by identifying the areas of performance which are not critical to operational capability and accepting lower standards (and use of existing equipment) in these areas. If this means a slightly smaller force then I submit this is the lesser evil.78
The implication of the postponement was a trough in the SSN building programme. While there would be eighteen SSNs by 1991, they would then fall to just fifteen by 1999. If force levels were not to fall dramatically a follow-on SSN would need to be ordered by 1992, requiring an Official Staff Target to be endorsed by 1985 at the latest. It was therefore imperative that studies be redirected as soon as possible, particularly if an SSN substitute were needed in the event of the cancellation of the SSBN successor. Was quantity the only yardstick? The cheapest, quickest solution would have been to reopen the ‘Trafalgar’ production lines. However, the Navy concluded that while the full SSN0Z design was too expensive for the follow-on SSN requirement, extending into the twenty-first-century the ‘Trafalgar’ submarine system, whose propulsion and tactical weapon systems as well as numerous other components stemmed from the 1950s, would be a false economy.
The Navy eventually settled on a follow-on SSN programme that exploited the advances made up to the start of the SSBN construction programme, with considerable savings on the estimated cost of SSN0Z. A Steering Group chaired by the Director of Naval Operational Requirements was tasked with ensuring that the optimum balance between operational requirements and costs was maintained. Consideration was given to building small nuclear submarines in the range of 2800–3000 tonnes. These submarines, described as Nuclear Patrol Submarines, were based on the Type 2400 design but stretched as necessary to include a new low-powered nuclear-propulsion plant. Although these submarines would have had a restricted performance compared with the ‘Trafalgar’ design, such disadvantages were offset by affordability.79 However, the Navy eventually concluded that to develop a new and indigenous Nuclear Steam Raising Plant was not achievable in the timescale of the project. Ways of adapting existing plant components, with significant penalties in terms of noise signature, available space for weapons, sensors and reactor safety constraints, were also explored as was the possibility of international collaboration. But it quickly became apparent that the most cost-effective solution was to use the new PWR2 plant, at that stage in development for the ‘Vanguard’ class. The PWR2 promised considerable advantages over the PWR1, including reduced noise signature, improved reactor core life, improved shock protection and more generous reactor safety margins. It could also be scaled to provide power to a secondary machinery set producing approximately 50 per cent of that in the Trident submarine.
However, if the Navy selected the PWR2 it would have to abandon the idea of designing a much smaller submarine, as the plant implied a hull size of a minimum of approximately 5000 tonnes.80 While this would undoubtedly increase the cost of the new class of submarine, it would also give considerable scope for the incorporation of a capable weapons/sensor system. This would be significant: many of the war games run by the Royal Navy revealed that in war its SSNs would be unable to make the most of what would be a ‘target-rich environment’ because they quickly ran out of torpedoes. Increasing the weapons complement on boa
rd any future SSN was therefore seen as very important.81 In late 1982, work was tentatively begun on a submarine that was more like ‘Trafalgar’ but with a cost increase of 10 per cent, rather than 38 per cent as with SSN0Z, and a proposed maximum displacement of 5000 tonnes submerged. The aim was to complete initial studies by 1985, when the naval architects involved in the Trident programme would become available, place the order for the first of class in 1992 and aim for an in-service date of 1998.
THE WALKER SPY RING
The Royal Navy’s decision to partly abandon its quality-over-quantity submarine philosophy could not have occurred at a worse time. The Navy was well aware that its considerable success against its Soviet adversary depended ‘largely upon the performance of passive acoustic sensors keeping pace with Soviet submarine noise reduction’.82 Submarine noise reduction was a complex task, involving a high quality of detailed engineering, and requiring an iterative process of trials analysis, design and refitting. The Navy estimated ‘that if the Soviet Navy pays unremitting attention to noise reduction their newer submarines might be approaching the performance of our Swiftsure class by 1990’.83 If that occurred, to preserve the Royal Navy’s passive superiority over the Soviets, the Navy would have to rely on the continuing presence of older Soviet submarines with relatively high noise levels, and the growth of passive sonar technology.84
For now, the Royal Navy still enjoyed considerable advantage over the Soviets, particularly when it came to trailing Soviet submarines. Since the introduction of the first towed-array systems in the late 1970s, a number of Royal Navy COs had become experts at exploiting narrowband information to detect and track Soviet submarines. (The CO of HMS Courageous, Dan Conley, earned the nickname ‘Dan, Dan the Narrowband Man’ due to his extensive knowledge of narrowband and towed-array operations.)85 Whereas in the 1970s, simply trailing Soviet submarines at long ranges was considered satisfactory, by the 1980s the Royal Navy no longer believed it was enough merely to maintain contact with Soviet submarines for extended periods. With the introduction of the Mark 24 Tigerfish torpedo, many in the Submarine Service argued that they now needed to demonstrate the ability to acquire and destroy Soviet submarines in warlike scenarios. Royal Navy submarines started to close Soviet submarines at the end of a trail and transmit on active sonar to see how they reacted. They also started to ‘mark’ Soviet submarines regularly, acquiring fire control solutions and carrying out simulated firings. ‘We all knew that at the end of the day we had to get a fire control solution,’ recalls Lane-Nott. ‘It was all very well trailing something, but you weren’t effective unless you could get a fire control solution and that you knew that if the torpedo worked properly you could fire and sink that submarine.’86