ALFA CLASS

Design development

Alongside the development of the Victor class attack submarines, another project team at the Malakhit bureau was tasked with developing a radical submarine concept which had been approved by the Council of Ministers on 27 May, 1961 – the Alfa class (Project 705). The design concept, hull and propulsion elements are dealt with in detail in the commentary to Plate D. The boats were equipped with a specially designed escape pod which could hold the whole crew and bring them to the surface in an emergency, and they were also able to fire torpedoes down to a much greater depth than previous classes. The boats had six torpedo tubes with twelve reloads and could also fire the V’yuga anti-submarine missile system from these tubes. They were highly manoeuvrable vessels but their high noise at speed meant that their own sonars could not operate efficiently, effectively making these vessels almost ‘blind’ when travelling fast.

	Project 705/705K
Length/beam/draft (m)	81.4/10.0/7.6
Displacement (tonnes) surfaced/underwater	2,300/3,100
Maximum depth (m)	400
Maximum speed (knots) surface/underwater	14/38.5
Endurance (days)	30
Complement	32
Armament	6 533mm torpedo tubes, 20 torpedoes
Sonar	Okean
Radar	Chibis
Radio/electronic systems	Akkord Sozh Molinya TV-1
Propulsion	Project 705: 1xOK-550 reactor Project 705K: 1xVM-40A reactor
Design bureau	Malakhit
Chief designer	M. G. Rusanov

D

ALFA CLASS CUTAWAY

This cutaway illustration shows an Alfa class submarine. The design incorporated three highly innovative elements. The first was the use of a liquid-metal reactor, similar to that which had been used in the single Project 645 submarine. This provided greater propulsion efficiency. Second, the submarine’s hull was constructed out of titanium alloy. This provided greater strength compared to steel and in practice meant 30 per cent lower mass (resulting in lower displacement and greater speed), a reduction in the boat’s magnetic field (and therefore its vulnerability to mines), and additional corrosive resistance, meaning that maintenance costs would be reduced. Titanium alloy had so far only been used to build the single Project 661 cruise-missile submarine, but this time the alloy would be used in a production submarine class with multiple vessels. Finally, and perhaps most radically of all, the whole design philosophy of the class was to maximise automation and minimise crew numbers, taking jet aircraft design concepts as inspiration. Through the automation of weapons loading, propulsion and navigation, combined with the development of a single combat and navigation system which centralised decision-making and activation into a single control room, the boat’s complement was reduced to only 32.

Despite being double-hulled, the Alfa class (Project 705) were small submarines, needing much less space for crew accommodation. They had one reactor driving a single screw, the Leningrad-built vessels with the OK-550 liquid-metal reactor and the Severodvinsk-built vessels with the VM-40A liquid-metal reactor. The former had three steam lines transferring heat to the generators, the latter two. As has been described with the Project 645 boat, the liquid metal had to be permanently kept at a high temperature (125 degrees Celsius) to avoid it solidifying and destroying the reactor. Initially this meant creating a sophisticated shore-based system of reactor heating for when the boats were alongside, but later it proved easier just to keep the reactors running permanently, which meant greater wear on the propulsion systems. This propulsion system, combined with the boats’ small size, meant that they could reach a maximum speed of an incredible 41 knots (albeit extremely noisily!).

KEY

1. Main command post

2. Veslo-P direction finder

3. Topol’ radio antenna

4. Chibis radar system

5. Periscope

6. Communications antenna

7. Torpedo reloads and rapid loading system

8. 533 mm torpedo tubes

9. Enisey sonar array (part of Okean sonar system)

10. SET-65 anti-submarine torpedo

11. 53-65K anti-ship torpedo

12. PMR-2 anti-submarine mine

13. Accumulator batteries

14. Compressor system

15. Galley and crew spaces

16. Sick bay and crew spaces

17. Reactor compartment

Two derivations of the Project 705 design were developed but not brought into production: the Project 705A design would have had launchers for six Ametist cruise missiles placed between the conning tower and the reactor compartment. The project was cancelled and cruise missile submarine production focused on the Project 670 boats instead. The second Project 705 derivative was the Project 705D: with a standard water rather than liquid-metal reactor. This too was cancelled.

A surfaced Alfa class submarine; considerable efforts were made to streamline the sail of the Alfa class to lessen underwater cavitation. (US Navy)

Construction programme

Five boats were ordered to be constructed at the Admiralty Yard in Leningrad with another three at Severodvinsk. Unfortunately, a major accident to the first vessel of the class whilst undertaking trials in 1972 halted the whole construction programme. As K64 was being made ready to go to sea, the lead-bismuth liquid metal in the reactor was accidentally allowed to cool and solidify, which in effect irreversibly stopped that boat’s reactor. The vessel was taken out of service and cut in half, with the forward section being used for training and the reactor section being stored at Severodvinsk. The Minister for the Shipbuilding Industry, B. Yu. Butoma, formerly a strong supporter of the programme, was so angered by this development that he called for the project’s cancellation. In the event, all but one of the vessels that were already under construction were eventually completed, but re-design work to rectify the problems that had caused the accident, meant that their completions were delayed for between two to eight years. No further vessels were ordered, and the eighth boat in the class was cancelled. Finally, in 1974, the chief designer, M. G. Rusanov, was relieved from this post.