Henry Knapp’s curious float torpedo (1875) used a bow propeller, only surpassed in eccentricity by Hugh Nealy’s float-supported clockwork-powered torpedo moved by means of its screw-shaped body (1887). Three float torpedoes made use of electricity: Henry Julius Smith (1872) employed it to steer, but ingeniously proposed using it to heat the compressed air for propulsion; Nordenfelt (1883), who tested a dirigible powered by batteries; as did Sims (1889) with the Sims-Edison. Alfred P S Miller (1887) proposed a torpedo shaped like a later Zeppelin gondola, and Patrick (1888) proposed a 24in float torpedo no less than 42ft (12.8m) long.
Gabet’s ‘torpille radio-automatique’ of 1909 was the swansong of the float torpedo. On 24 December 1909 French inventor Gustave Gabet tested his radio-controlled torpedo in the Seine near Paris. A journalist described it as a dirigible (or steerable) torpedo, with a length of some 30ft (9m). It was of the float torpedo type, the lower cylinder containing the electric batteries and 200hp motor being suspended from a smaller upper cylinder which carried two lamps set on pillars of different heights. The proposed warhead was to comprise no less than 1980lbs (900kg) of dynamite. The powerful electric motor was hoped to give the torpedo a top speed of 20 knots. Gabet claimed to be able to control his torpedo out to a maximum radio range of 14,000yds (13,000m), but it was certain that the batteries would not suffice to drive the torpedo at 20 knots for this distance. He stated his torpedo would cost around £3000, which was a substantial sum in 1909.
The trial run seems to have succeeded. The torpille radio-automatique appeared to be a workable vehicle, but of course it suffered from the lack of a stealthy approach common to all float torpedoes. Added to this major tactical drawback, its large size meant it was extremely expensive, and therefore it is no surprise Gabet’s invention was never followed up. It has to be said that 20 knots, while a respectable speed for a torpedo of the 1870s, was nowhere near fast enough to catch any worthwhile prey forty years later.
Another journalist, writing in the Reading Eagle of Tuesday, 4 January 1910, appeared to be confused over the torpedo’s motive power, claiming that the batteries were only fitted to work a system of signal lamps — described as ‘acetylene’ lamps by the previous correspondent — and that the torpedo was to be driven by a 200hp petrol engine! Since he also reported that the propeller was readily reversible, and one cannot envisage a gearbox operated by remote control at that date, the reference to a petrol engine has to be an error.
Apparently, the lights served as signals to the controller, since as Monsieur Gabet related, ‘It does not suffice to direct a torpedo boat, one must also know what is happening inside. For that reason the lights undergo eclipses [sic], which reveal to the operator placed on shore the nature of the command received by the torpedo boat. He is thus informed a couple of seconds ahead when such and such a manoeuvre is going to be made, and thanks to this optical control he can intervene to correct an error or to annul a disturbing wave.’
Wisely, before building his torpedo Gabet had filed a US Patent, № 907488A, describing himself as a ‘professor’ (schoolteacher) living in Rochefort-sur-Mer. The patent specified an apparatus ‘whereby it is possible to operate from a distance by luminous and electrical waves an engine, rudder, a dirigible torpedo, a signal or any other mechanism.’
THE SURFACE-RUNNER
The third category was the surface- or awash-runner, which had the same advantages and disadvantages as the float torpedo. These were designs from Ericsson (1870), Lay (1872), George H Reynolds (1881) and Berdan (1883) and, although each one ultimately failed, they did exhibit certain notable features.
The most significant of the hopefuls predates Brennan. It was that prolific inventor Ericsson, designer of the USS Monitor, who tested his steerable pneumatic torpedo in around 1872. A large, clumsy device which ran on the surface, controlled by varying the pressure in the air hose it trailed out behind it, the Ericsson torpedo was remarkable for one major innovation, the contra-rotating two-bladed propellers, the first to be used in a practical application, although the torpedo they drove was a signal failure.
The Ericsson pneumatic torpedo consisted of a rectangular box constructed of iron plates riveted together, 8ft 6in in length by 20in wide and 30in deep (2.6m × 0.5m × 0.76m). It weighed in at 2000lbs (907kg), of which 400lbs (181kg) was the nitroglycerine warhead. Its clumsy shape meant that it could not be launched from a torpedo tube, but had to be lowered into the water by ship’s davits. The use of the highly volatile nitroglycerine would not have endeared it to potential users.
One thing the Ericsson had was a certain turn of speed, for its two-cylinder oscillating engine, powered from a distance by a trailing air hose, drove it along at 10 knots, or slightly more than the contemporary Whitehead, and to a maximum range of around 880yds (804m). However, the need to drag behind it the unrolling air hose rendered it virtually uncontrollable when approaching its maximum range. As Edwyn Gray so succinctly noted, the Ericsson was a typical Victorian monstrosity, especially when compared with the sleek Whitehead which, in much modified form, is still with us today.
John Louis Lay came to fame through his invention of the spar torpedo used by Lieutenant Cushing to sink the Albemarle. Unfortunately, when he turned his hand to dirigible torpedoes, his designs showed a high degree of complexity, but a disappointing lack of effectiveness. An awash-runner, his torpedo had a warhead of 500lbs (227kg), almost five times the size of that in the contemporary Whitehead, necessary because his weapon would strike an enemy ironclad at its least vulnerable spot, on the waterline armour belt.
Various dimensions have been quoted for Lay torpedoes, but at between 3ft and 3ft 6in in diameter (914mm to 1067mm) and between 23 and 25ft long (7m to 7.62m), they were certainly impressive. Powered by carbolic gas which was prevented from freezing by running the feed pipes external to the torpedo body, it was demonstrated as capable of a speed of 9 knots over a distance of 3000yds (2745m) and more. A dirigible torpedo, it was steered from the shore or a launch vessel by electric cables from a highly complicated control box.
Lay’s giant torpedo made a good impression — except on its Peruvian customers as noted in Part IV — but the British Admiralty summed up its main drawback: a price tag of £2200, or more than seven times the price of the rival Whitehead.
Reynolds’ patent (1881) described an awash torpedo controllable in depth as well as direction from the shore by insulated cable, and was notable for using the heating properties of the surrounding seawater.
In complete contrast, Hiram Berdan (1882), well-known for his Sharpshooters regiment in the US civil war and later work in cartridge and rifle development, seemed to have gone adrift with his proposal for a surface-runner torpedo, propelled by powder charges, steered by tiller ropes, and towing behind it a second torpedo carrying the warhead.