Robert Whitehead continued to gain official favour, building the steam engines that powered the Ferdinand Max to victory at Lissa, and making them robust enough to stand up to the shock of ramming. And all the time his fertile mind turned over the idea of de Luppis’ device, analysing its drawbacks and working out solutions, as we shall see in Chapter 4.
THE LEGACY OF THE KÜSTENBRANDER
De Luppis may have died a disappointed man, believing that Whitehead had taken his idea and turned it into something completely different, but the idea of the Küstenbrander lived on. In particular, later inventors seized on the one aspect of de Luppis’s idea that Whitehead had ignored when building his own fish torpedo: the attempt to direct it throughout its trajectory by remote control.
The renowned inventor Nikola Tesla patented radio control in 1898, and used it to direct his remote control boat, which he called the ‘Telautomaton’, which was 6ft (1.83m) long, built of iron and powered by an electric motor driven by two batteries. Tesla demonstrated its potential on an artificial lake in Madison Square Garden just after the end of the Spanish-American War.
He claimed he could build a larger version with an explosive warhead, to attack enemy ships. Not surprisingly, there were no takers. As a surface runner, the Telautomaton would have needed high speed, first to catch an alert target ship, and second, to rapidly run the gauntlet of the intended victim’s defensive fire.
On 28 October 1917 the Royal Navy monitor HMS Erebus was attacked off the coast of Flanders by explosive German motorboat FL 12, directed by radio and spotted by an aircraft: the ‘ Fernlenkboot ’, or FL-boat, built by Siemens — Schuckertwerke blew a 50ft — long hole in the anti-torpedo bulge, but Erebus survived the attack.
Previous attacks had failed, the first when an FL-boat hit the mole at Nieuport, and then when a smaller monitor destroyed another FL-boat with gunfire. It is often reported that the FL-boats were spotted by aircraft but controlled from the shore by cables. The Siemens Archive photos show that in fact the FL-boats were directed from the spotter aircraft by radio control, as evidenced by their high radio-antenna masts fore and aft. The top of the hull was painted white to aid the observer in the controlling aircraft. With a length of 17m, they carried a 700kg explosive charge, and were propelled by a petrol engine at speeds of up to 30 knots.
Then in the Second World War, the Italians developed and used with some degree of success their ‘barchino esplosivo’ Type MT. This ‘exploding motorboat’ was operated by the famous Decima MAS, a cover name for the stealth units of the Regia Marina.
The method of operation was simple, but extremely hazardous. Carried to the scene of action by a mother craft, the MT-boat’s pilot steered directly for his target, set the charge to explode on contact, locked the controls and threw himself backward into the water, cradling in his arms his large, folded, back-rest cushion. The cushion floated, and he hauled himself up out of the water and onto his tiny raft, in order to escape the shock wave of the imminent explosion.
The immensely brave and dedicated pilots succeeded in crippling the British heavy cruiser HMS York in Suda Bay, Crete, on 25 March 1941 and sinking an oiler. The cruiser was beached with her engines out of action, and despite desperate efforts to repair her, she was wrecked by Stuka dive-bombers and scuttled.
On 26 July 1941 Decima MAS attempted a major attack on Malta’s Grand Harbour, which failed disastrously, through British early warning radar and the rapid-firing twin 6pdr guns of the coastal defences, and the unit’s leaders were killed.
‘Linse’ in German means ‘lentil’, an appropriate name for the tiny, skimming explosive motorboats with which the Kleinkampfverband, or ‘small battle units’, were supposed to stop the Allied invasion of Fortress Europe — alongside the Neger, Molch and Seehund midget submarines. Of all the special attack units, the Linse seemed, even to its operators, to be the most suicidal. No doubt inspired by their Italian allies’ success with the MT-boat, the Germans decided to copy the idea but go one stage further, combining raw courage with more advanced technology.
The Linse was a small wooden motorboat powered by the ubiquitous Ford V-8 petrol engine, with a reliable output of 95bhp. That was sufficient to propel these 1.8-ton 5.75m (18ft 10in) long × 1.75m (5ft 9in) wide boats at a top speed of 35 knots. In the stern compartment was a 300kg (660lbs) explosive charge, with a 7-second delay fuse. The charge in later boats was increased to 400kg (880lbs). They were intended to be used in groups of three, two filled with explosive and steered by one man, and a third control boat, with a crew of three in a large rear compartment: the helmsman and two radio operators each directing an explosive Linse.
The explosive-boat pilots, who were less likely to be volunteers, but rather, picked from a penal battalion, would head at full speed for their chosen target. At the last moment they would illuminate red and green lights fitted to the stern of their Linse, and bale out into the water, hoping to be picked up by the following control boat. The crew of the latter would, however, already have their hands full, using the red and green lights to direct the two Linse by radio control during the final part of their attack run. The radio system used was that taken from the Goliath remote control demolition tank, and was well-proven.
If all went well, each Linse would impact on the hull of the target vessel, when a metal framework around the bow would compress and fire a small explosive charge. This would blow off the bow section, leaving the rear section carrying the main charge to sink below the waterline of the victim. After 7 seconds the delayed action fuse would operate and blow the main charge. At that moment it was to be hoped that the crew of the control boat had faithfully followed their pilots and recovered them out of the water. Lacking the large floating cushion of the Decima MAS pilots, they would be at fearful risk of concussion from the blast.