Bellerophon-class Ballistic Missile Submarine

Roger Burton West
11 August 2010

Table of Contents

1. History

The replacement of the Vanguard class of ballistic missile submarines was politically contentious as long ago as 2009. It was decided fairly early on that the same Trident D5 missiles would be used, but that a new class of submarine would be built to carry them; who was to pay for it was another matter, to the extent that while the Vanguards had originally been slated to retire from 2025, they were still in service by 2029, when Vigilant was lost to what turned out to be excessively optimistic calculations of fatigue life.

HMS Bellerophon was commissioned in 2032, just in time for the Spasm; Benbow followed in 2033, Britannia in 2034 and Barham in 2035. While no boat was lost to robot subversion during the Final War, the latter two were designed without the semiautonomous maintenance systems that were present on the earlier vessels.

2. Description

The four boats of the Bellerophon class were laid down from 2020, but repeatedly mothballed and redesigned during construction. It was felt that, with a nuclear war generally considered quite unlikely, the vessels ought to have some other role: their torpedo tubes were already capable of firing a variety of navalised cruise missiles, but their missile tubes were also equipped to make it possible to carry diver tugs, UUVs, or bundles of smaller missiles, without major reconstruction being necessary. Experience of refuelling earlier submarines led to the use of a full-life reactor, which should not require refuelling during the service life of the submarine.

The Bellerophon is a derivative of BAE's Advanced Hull Form proposal, one of the first submarines to break away from the teardrop shape pioneered by USS Albacore. The computer-modelled shape is relatively simple to fabricate, and offers significant reduction in flow noise.

(Image from Navy Matters,

From the front of the craft, components are approximately:

Ballast tanks, batteries, and sonar emitters and receivers are spread throughough the hull.

3. Statistics

TL Vehicle ST/HP Hnd/SR HT Move LWt. Load SM Occ. DR Cost Loc. Draft
9 Bellerophon 1227 +1/6 12 20 14426 1031 +10 70AP 200 $8B s 40

3.1. Trident D5 nuclear missile

The Trident D5 (or UGM-133 Trident II) has remained essentially unchanged since it was brought into service in 1990.

Warheads in British service have selectable yield of 0.3, 5-10, or 100kt. Each missile carries up to 8 warheads, which may be independently targeted up to about 200 miles apart.

Warhead Damage
0.3 kiloton 6dx1100 cr ex
linked 4dx1100 burn ex* rad sur
7.5 kiloton 6dx5500 cr ex
linked 4dx5500 burn ex* rad sur
100 kiloton 6dx20000 cr ex
linked 4dx20000 burn ex* rad sur

3.2. Francisca

This Anglo-German cruise missile design came into service in 2023, a derivative of Storm Shadow clearly inspired by the Tomahawk. It is faster and longer-ranged; its warhead is the same, but in service this was often swapped out for a substantial sensor package and the missile operated as a UAV. (While it can land on a runway and be refueled and used again almost at once, repackaging it for a torpedo tube launch takes rather longer.)

3.3. Sea Shadow

This is a derivative of the Storm Shadow ALCM, modified with a booster and swim-out capability for naval use. It entered service in 2015.


TL Weapon Damage Acc Range Weight RoF Shots ST Bulk Rcl Cost LC
9 Trident D5 spec. 10 6600/12.32M 130,000 1 1 n/a n/a n/a $31M 0
9 Francisca 6dx22(10) cr ex 6 330/4.4M 3,200 1 1 n/a n/a n/a $5M 1
  follow-up 6dx80(10) cr ex                    
  linked 6dx34 cr ex                    
9 Sea Shadow 6dx22(10) cr ex 6 300/273,000 4,000 1 1 n/a n/a n/a $1M 1
  follow-up 6dx80(10) cr ex                    
  linked 6dx34 cr ex                    

3.4. Spearfish Mod 3

In its Mod 2 incarnation, the Spearfish gained an entirely new propulsion system derived from the German DM2A4 Seehecht; the Mod 3 brought in an entirely new seeker logic. It is guided by optical fibre cable, and can home with its wake sensor or its own inbuilt sonar. It is designed to double as an ROV; in theory it can reinsert itself into its controlling submarine's torpedo tubes once a mission is complete, but few crews are foolhardy enough to test this.


TL Weapon Damage Acc Range Weight RoF Shots ST Bulk Rcl Cost LC
9 Spearfish Mod 3 6dx23(10) cr ex 6 50/30,000* 4,000 1 1 n/a n/a n/a $2M 1
  follow-up 6dx87 cr ex                    
  linked 6dx36 cr ex