FLYING TORPEDOES
This section describes torpedoes which were intended to fly to the vicinity of their target, where they would join their natural environment and make the final part of their one-way journey underwater. The modern term would be a ‘stand-off torpedo.
The Kaiser’s navy experimented with radio and cable control during the Great War, producing the successful FL-boats described earlier. The same Siemens designers also came up with an idea for a stand-off glider torpedo to be launched and controlled from a Zeppelin.
The original idea was to resolve two problems facing Zeppelin crews: first, their commanders were unwilling to bring their huge aircraft down to torpedo-launching height because of the ground effect and the difficulty of executing rapid climbs and avoiding action; second, they wanted to keep well out of range of the anti-aircraft guns which were sprouting on the decks of British warships.
Developed from 1916 onward, the ‘Torpedogleiter’ (‘torpedo glider’) was designed to be dropped from a Zeppelin from an altitude of 1000–1500m (3300–4900ft). Control by radio was rejected because of the weight of the receiver equipment. Already, to be able to carry a torpedo, the gliders had progressed from monoplane to biplane designs, to reduce the wing loading. Controlled by electrical signals sent from the Zeppelin down a thin wire, the glider was supposed to launch its torpedo between 100 and 200m (110–220yds) from the target, allowing the latter little time to take avoiding action. Tests were carried out with a dummy wooden torpedo weighing 900kg (1984lbs), but difficulties were experienced in controlling the final underwater trajectory of the torpedo once released from the glider. Despite this, trials continued, and a maximum glide range of 7km (4.35 miles) was eventually achieved.
The trials gave encouraging results. But the entire programme was negated by the fact that in late 1918 many British warships were carrying protective fighters such as the Sopwith Camel — to be used in a similar way to the later Camship Hurricanes on the Murmansk route: the pilot would take off in extremis when his ship was threatened and would ditch alongside an escort vessel to be picked up. And in addition, early aircraft carriers such as the unsatisfactory HMS Furious and the more practical HMS Argus were coming into service. Brave would be the crew of a Zeppelin which ventured too close to such a hornets’ nest of fighters. But then of course, that left the night attack, preferably by moonlight, to observe the flight of one’s own stand-off torpedo.
In the late 1940s British designers drew up projects for a range of futuristic weapons.
Described as a ‘submersible torpedo launcher’, the Zannet would have had four retractable biplane wings semi-recessed into the body, two shrouded propellers, one for air travel and the other for underwater propulsion, and a pair of bow doors which opened to release a torpedo once it had plunged beneath the surface. In the photograph it is shown as it would be submerged, with radio mast erected, and the bow torpedo launch doors open.
A slightly less far-fetched idea was the project for a flying torpedo, this time with only one set of wings retracting into the body; in fact, the ‘Z-weapons’ were intended to comprise a complete range of winged torpedoes:
Zonal, a sea-skimmer anti-ship torpedo launched from a tube on the carrier ship. Its three-cylinder, six-piston, hollow-crankshaft engine was to produce 900hp, to propel it in the air at 500 knots at low altitude. Out of range of the target’s anti-aircraft guns, the wings would retract and it would enter the water, proceeding to its target at 60 knots, with active homing guidance. The same ducted propeller was to be used in the air and in water, with a change of gearing.
Zoster, an air-launched anti-ship version of Zonal.
Zombi, a submarine-launched homing version.
Zeta, an anti-submarine air-launched weapon.
Dewlap, a 21in diameter version for launching from MTBs.
A drawing dated 1947 shows one form of Z-weapon with an elliptical body and chisel nose, to cushion the shock of water entry. However, this form of body reduced the internal space for the retracting wings. One must wonder why the designers did not copy the solution adopted by Siemens-Schuckert, to jettison the wings prior to water entry. After all, they were only needed for flight, being initially retracted to be fired from a tube launcher, and they served no purpose once the weapon was submerged.
All these propeller-driven weapons were completely anachronistic in the age of the missile, and despite extensive tank and wind-tunnel model testing, no full-size versions were actually constructed.
It is sobering to think that this was a glorious period when engineers imagined anything would shortly become possible. The author remembers seeing a cutaway colour illustration in the Eagle, a popular boys’ comic of the early 1950s, depicting a nuclear-powered road truck.
MODERN STAND-OFF WEAPONS
A modern anti-submarine vessel needs to be able to carry out an attack on a submarine at long range, to avoid the danger of herself being attacked by torpedo. In addition, lightweight anti-submarine torpedoes have a strictly limited range compared with 21in torpedoes, typically only 4 nautical miles (7400m) for the Mark 46. Another problem is that with their slow speed, these torpedoes can take over eight minutes to reach their maximum range, after which their fuel is exhausted and they cannot carry out a search pattern. Meanwhile, during the slow approach of a Mark 46, the submarine target can profitably use the time to evade, warned by the initial shipborne sonar signal.
One way to cut down on this reaction time is to use a helicopter to carry the torpedo to the detected position of the submarine. This would require that the helicopter is crewed and armed and ready for immediate takeoff, and its relatively slow speed still allows the target time to evade, and even to counter-attack.
In order to provide ASW defence, the Royal Navy and other Western navies possessing small aircraft carriers converted a number for ASW capability, landing their fixedwing air contingents and even removing the catapult and arrester gear, and instead shipping a number of ASW helicopters. In place of a rapid-reaction defence, in a war zone they would fly continuous anti-submarine patrols in the same way as their predecessors, the Swordfish and Avengers, had done from ‘jeep’ carriers in the Second World War.
On smaller escort vessels, helicopters require significant deck space for their rotors. In addition, when not in use they need protection against the elements and rough seas, so that a hangar is required. One reason why the Royal Navy withdrew many of its escort vessels in the 1970s was the sinking of the Indian Type 14 frigate Khukri by the Pakistani submarine Hangor in December 1971. Escorts too small to operate helicopters were thought to be too vulnerable to attack by modern submarines.
The US Navy took a different route when, at the height of the Cold War, they realised that the Soviet Navy was commissioning new submarines faster than the Americans could build new escort frigates. The US Navy was therefore obliged to upgrade its large fleet of late Second World War destroyers to meet the increased ASW threat. Unable to operate even the small helicopters of the day, these conversions were equipped with a remotecontrolled DASH (drone anti-submarine helicopter). The Gyrodyne QH-50 DASH, powered by a 255shp turboshaft engine, which came into service in 1963 was capable of carrying two Mark 44 or 46 torpedoes at up to 80 knots, over a range of 71 nautical miles.