HARD-KILL SYSTEMS
The modern alternative to this ‘soft-kill’ approach is to react with a ‘hard-kill’ weapon, which will destroy the incoming torpedo.
The Royal Navy spent a great deal of time and money in developing the Camrose 18in anti-torpedo rocket torpedo, which merged with the Bootleg design. Test runs had produced an underwater speed of 65 knots, and the homing circuitry was proving workable. However, it was feared that frigates would not be capable of carrying sufficient Camrose/Bootleg missiles for a protracted defence in hostile waters, so the project was cancelled. One prototype is preserved in storage at Explosion, the Museum of Naval Firepower at Gosport.
The Russian Shkval has been discussed in Part I. It is mentioned here again because, in order to avoid torpedo attack from another submarine, the Shkval can be used to put in a first strike attack itself. As discussed, its ability to block an incoming torpedo is strictly limited unless the Shkval is armed with a nuclear warhead.
This is a smaller-diameter rapid-reaction anti-torpedo hard-kill weapon, marketed by the Russian Tactical Missile Corporation. Paket is 324mm in diameter, the standard 12.75in ASW torpedo size, 3.108m (10ft 21/2in) long, and weighs 400kg (882lbs) with an 80kg (176lbs) warhead. It can be fired in all weather conditions up to sea state 5, wind speed not exceeding 20m/sec and a launching vessel speed of up to 20 knots. Temperature is not a serious consideration, as Paket can operate in -40 °C to +40 °C. Minimum depth of water is 40m (130ft), so it might not be effective in inshore waters where seabed reflections could confuse its homing signals.
After launch it attains a cruising speed of 25m/sec (56mph/64.5 knots) with a maximum range of 1400m (1530yds). Its active and passive homing sensors are effective up to 400m (437yds).
An illustration from Raphael Industries’ brochure showing the Torbuster anti-torpedo torpedo interceding between its launch submarine and an incoming threat. Described as a fourth-generation hard-kill countermeasure, the Israeli-produced Torbuster homes on the incoming torpedo and then detonates to destroy it.
This modern development, aimed at protecting aircraft carriers from submarine torpedo attack, is based around the new US Navy’s hard-kill ATT (anti-torpedo torpedo) with a diameter of 6.75in (171mm), 105in (2.7m) long, weighing 200lbs (441kg). The ATT relies on a sophisticated detection and warning system, which gives the target the option of an automated defensive launch. The ATT is particularly useful against wake follower torpedoes, and the ‘surface ship torpedo defense’ will be fantail-mounted on all US aircraft carriers, following tests on the USS George H W Bush in 2013.
THE HUNTER-KILLER
All the above modern systems are basically last-ditch defences. They rely on being able first, to detect the presence of a submarine threat, then second, to detect an incoming torpedo fired from it. The speed of modern torpedoes leaves precious little time to react.
Just as with the threat of the torpedo boat, when the best gamekeeper was an ex-poacher, the best defence against a submarine threat is your own hunter-killer submarine, which can shadow a hostile boat and detect when it is preparing to launch against one’s own side. At that point, the speed of your own torpedo becomes an advantage in taking out the hostiles before they themselves can obtain a firing solution and launch. The encounter off the Falklands proved this point, even though the target was a surface vesseclass="underline" the moment General Belgrano appeared as a credible threat to the British Task Force, the nuclear hunter-killer submarine that had been shadowing the cruiser took her out with a well-aimed salvo of torpedoes.
Part IV
Notable Torpedo Actions and Incidents
CHAPTER 19
Torpedo Attack Tactics
The original plans by Fulton were for stealth attacks by very small units, each one incapable of standing up to the target in a firefight. Attacking by night, using pilots clothed in black — these were his watchwords for success. Because of the lack of a suitable means of motive power, his stealth weapons relied on wind, tide and manpower to place them in position. His submarine attack boat also fitted in with this stealth approach, but once again lacked a suitable power source to be really effective. Spar torpedo attacks also offered the prospect of most success when carried out by stealthy approach under the cover of night. The introduction of the reliable steam engine dramatically changed torpedo attack tactics, although even the revolutionary torpedo ram HMS Polyphemus ended up painted grey — in an era of colourful Victorian liveries — to aid her in carrying out stealth attacks.
The French navy of Napoleon III tried to counter British supremacy in capital ship design by building large numbers of small torpedo boats. This gave them the ability to plan for mass attacks, to overwhelm each individual target vessel with a swarm of attacking torpedo boats. As a result of extensive exercises, the French calculated that, if an ironclad was attacked by at least three torpedo boats simultaneously, the attackers stood a good chance of hitting her. But small torpedo boats meant limited range and poor sea-keeping, so they underwent rapid growth in size and power. For their part, at the turn of the nineteenth century the Imperial Japanese navy preferred to carry out night torpedo attacks, usually of a first-strike nature.
When submarines became workable, they reverted naturally to the stealth attack from submerged against an armed opponent, but when faced with a helpless merchant vessel they would revert to the surface warship role, using their deck gun to economise on torpedoes. The German U-boats of the Second World War might hunt in packs, but when they took on a located convoy it was by stealth that they attacked, either from submerged or by acting as surface torpedo boats by night.