It required two pilots, one to effect take-offs and landings, and the second situated inside the launch ship’s CIC to direct the drone to where it would drop its homing torpedoes. On the other hand, it economised in deck space by using two small-diameter axial rotors. Despite reliability problems, it was eventually made to work, and was also adopted by the Japanese self-defence force. However, the US Navy gradually phased out its ASW drones in favour of more flexible and capable manned helicopters, and the Japanese were obliged to follow suit.
However, recently there has been a revival of interest in unmanned aerial vehicles. The latest USN drone is the Northrop Grumman MQ-8 Fire Scout, which in its MQ-8C version can carry a payload of up to 700lbs (318kg). Interestingly, it is also capable of autonomous (i.e., not under human pilot control) landings and take-offs from parent vessels. It has not so far been cleared for ASW operations, this role being reserved to piloted helicopters.
An alternative solution is the stand-off missile. The most significant of these follow.
The French Malafon was produced by Groupe Latécoère and entered service in 1966. The torpedo body was enclosed in an unpowered glider, the complete weapon weighing 1330kg (2930lbs). Launched by solid fuel booster rockets at a fixed angle of +15 degrees, it accelerated to 830kph (516mph) when the rockets detached, leaving the Malafon to glide a maximum of 13,000m (8 miles) at a height of 100m (328ft).
Teleguided from the launch vessel, when it reached the sonar position of the submarine target the glider was directed to release the torpedo, which on entering the sea commenced a search at 30 knots. The in-flight guidance meant that the Malafon could be directed onto a new sonar bearing, but its relatively slow glide time still allowed the submarine to put in an attack of its own. Malafon was withdrawn from service in 1997.
The Australian-built Ikara, named for the Aboriginal word for a ‘throwing stick’, was a powered stand-off weapon, a winged rocket which carried its anti-submarine torpedo in its belly. Carrying a Mark 44 or Mark 46 homing torpedo, the Ikara accelerated to a cruising speed of 409mph (658kph), and had a maximum range of 10 nautical miles (19,000m) which it reached in around 100 seconds of flight time. Releasing its torpedo by radio guidance, the missile carried on to splash down some distance away from its torpedo in order to not disturb the latter’s homing sensors. Ikara was used from the early 1960s by several navies, up until the end of the 1990s.
ASROC’s initials stand for ‘anti-submarine rocket’. It entered US Navy service in 1961, and has since been fitted on over two hundred American warships, as well as on those of many other navies. It consists of a Mark 46 antisubmarine homing torpedo mounted on the nose of a solid fuel rocket with a maximum range of 12 miles (19,000m). On reaching the sonar position of the attacking submarine the torpedo separates from the missile body and parachutes to a sea entry to commence its search.
First launched from an eight-tube mounting, which could also carry other missiles such as the Tomahawk, the ASROC’s latest two-stage versions are vertically launched from a deck silo. The vertical launch version went into service in 1993, and from 2004 the torpedo carried is the Mark 54. The new ASROC maximum range has been extended out to 11.8 nautical miles (22,000m).The ASROC’s advantage over Malafon and Ikara is that it is much more compact, which allowed the use of multiple launchers and, more recently, the vertical launch cells.
Since maritime patrol aircraft conduct surveillance from high altitude, to economise on fuel on long missions and to cover a wide search area, to descend from 30,000ft to 100ft in order to drop their anti-submarine torpedo would take many minutes, allowing the submarine a chance to evade. The aircraft would then also burn more fuel in climbing back to patrol altitude. Boeing have therefore designed the ‘high altitude anti-submarine warfare weapon capability air launch accessory’.This converts the standard lightweight Mark 54 anti-submarine torpedo into a standoff weapon capable of being released at cruising altitude. After gliding for between seven and ten minutes the torpedo will enter the water when the wings will detach. This attachment allows the P-8A crew to launch from a stand-off distance well outside the cover of shore-based anti-aircraft defences.
CHAPTER 15
Coast Defence
BRENNAN LAUNCH STATIONS
Several Brennan stations were sited around the coast of the British Isles, at Cliffe in the Thames, at Garrison Fort, Sheerness, in Fort Albert on the Isle of White, at Pier Cellars in Plymouth, and at Fort Camden, Cork, Southern Ireland. A further station was planned for Milford Haven but the site was eventually used to house a Zalinski dynamite gun.
Overseas there was a Brennan station at Lye Mun defending Hong Kong, and two at Malta. The first of the Maltese sites was in Fort Tigné and covered the entrance to Marsamxett Harbour and the northern approaches to Grand Harbour, and the second was sited in Fort Ricasoli, on the southern entrance to Grand Harbour, with its torpedoes running inside Grand Harbour itself.
One major drawback to the Brennan system was the fact that the torpedoes on their launch ramp would be in plain sight of the intended target ship, at relatively close range. The launch mechanism itself hardly helped matters, as it consisted of a long overhead girder carrying the winch carriage bracketed out above the launching rails. There was no obvious way to disguise this fitting, although an armoured mantlet was planned to be installed over the launch mechanism at Tigné. However, being sited on the harbour side of the fort, the Ricasoli station was concealed from an enemy vessel entering Grand Harbour, and launched its torpedoes from an ambush position.
In operation, the two wires emerging from the tail of the torpedo were passed through the travelling pulley carriage at the rear of the girder, round the steering pulleys and dynamometer pulleys, and finally were connected to the wire drum on the right in the drawing. The winding engine was then started and the liberating bolt released. The torpedo then began to run down its launch rails, the two propellers turning. When it entered the water, the increased stress on the wires by the propellers being immersed caused the travelling pulley carriage to run out to the left to the end of the overhead girder, powered by the drive pulley at the rear of the carriage engaging with the rack on the girder. At the end of the girder the drive pulley disengaged and the pulley carriage would stop. The torpedo continued on to its target, being steered as necessary by moving apart the two steering pulleys.