The Brennan torpedo was a torpedo patented by Irish born Australian inventor Louis Brennan in 1877. It was powered by two contra-rotating propellors that were spun by rapidly pulling out wires from drums wound inside the torpedo. Differential speed on the wires connected to the shore station allowed the torpedo to be guided to its target, up to 2,000 yards (1,800 m) away, at speeds of up to 27 knots (31 mph).
The Brennan torpedo is often claimed as the world's first guided missile, but guided torpedoes invented by John Ericsson, John Louis Lay, and Victor von Scheliha all predate it; however, Brennan's torpedo was much simpler in its concept and worked over an acceptable range at a satisfactory speed so it might be more accurate to call it "the world's first practical guided missile".[1]
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The Brennan torpedo was similar in appearance to more modern ones, apart from being having a flattened oval cross-section instead of a circular one. It was designed to run at a consistent depth of 12 feet (3.7 m), and was fitted with an indicator mast that just broke the surface of the water; at night the mast had a small light fitted which was only visible from the rear.
Two steel drums were mounted one behind the other inside the torpedo, each carrying several thousands yards of high-tensile steel wire. The drums were connected via a differential gear to twin contra-rotating propellers. If one drum was rotated faster than the other, then the rudder was activated. The other ends of the wires were connected to steam-powered winding engines, which were arranged so that speeds could be varied within fine limits, giving sensitive steering control for the torpedo.
The torpedo attained a speed of 20 knots (23 mph) using a wire .04 inches (1.0 mm) in diameter but later this was changed to .07 inches (1.8 mm) to increase the speed to 27 knots (31 mph). The torpedo was fitted with elevators controlled by a depth-keeping mechanism, and the fore and aft rudders operated by the differential between the drums.
In operation, the torpedo's operator would be positioned on a 40 feet (12 m) high telescopic steel tower, which could be extended hydraulically. He was provided with a special pair of binoculars on which were mounted controls which could be used to electrically control the relative speeds of the twin winding engines. In this way he was able to follow the track of the torpedo and steer it with a great degree of accuracy. In tests carried out by the Admiralty the operator was able to hit a floating object at 2,000 yards (1,800 m) and was able to turn the torpedo through 180 degrees to hit a target from the off side.
According to Brennan's biographer, Norman Tomlinson, Brennan was inspired to create his torpedo's unique propulsion system in 1874, when he noticed that a cotton reel, if the thread is pulled toward the operator from underneath, moves forward rather than backward. He also realized that the only device which needed propulsion for a limited distance and which did not have to make a return journey, was a torpedo.
Brennan began making rough sketches of such a torpedo, and as the concept developed he sought the mathematical assistance of William Charles Kernot, a lecturer at Melbourne University.[1]
After earlier experiments with a single propeller, by 1878 Brennan had produced a working version about 15 feet (4.6 m) long, made from iron boiler plate, with twin contra-rotating propellers. Tests carried out in the Graving Dock at Williamstown, Victoria were successful, with steering proving to be reasonably controllable, although depth-keeping was not.
The British Admiralty had meanwhile instructed Rear Admiral J. Wilson, the Commodore of the Royal Navy's Australian Squadron, to investigate the weapon and report back. Alexander Kennedy Smith was also working to obtain the Victoria government's backing for the project and raised the subject in the state's legislature on 2 October 1877. A grant was eventually awarded for the development of the torpedo, and in March 1879 it was successfully tested in Hobsons Bay, Melbourne.
Brennan had by now established the Brennan Torpedo Company, and had assigned half of the rights on his patent to civil engineer John Ridley Temperley, in exchange for much-needed funds. Brennan and Temperley soon afterwards travelled to Britain, where the Admiralty examined the torpedo and found it unsuitable for shipboard use. However, the War Office proved more amenable, and in early August 1881 a special Royal Engineer committee was instructed to inspect the torpedo at Chatham and report back directly to the Secretary of State for War, Hugh Childers. The report strongly recommended that an improved model be built at government expense. At the time the Royal Engineers - part of the Army - were responsible for Britain's shore defenses, while the Royal Navy were responsible for its seaward protection.
In 1883 an agreement was reached between the Brennan Torpedo Company and the government. The newly appointed Inspector-General of Fortifications in England, Sir Andrew Clarke, appreciated the value of the torpedo and in spring 1883 an experimental station was established at Garrison Point Fort, Sheerness on the River Medway and a workshop for Brennan was set up at the Chatham Barracks, the home of the Royal Engineers. Between 1883 and 1885 the Royal Engineers held trials and in 1886 the torpedo was recommended for adoption as a harbour defence torpedo.
In 1884 Brennan received a letter from the War Office stating that they had decided to adopt his torpedo for harbour defence and he was invited to attend a meeting to decide the value of his invention. Brennan decided to accept £40,000 as a quick answer to his financial worries but his business partner J.R. Temperley assumed control of the negotiations and demanded £100,000. The War Office agreed to this, but said that it would have to be paid out over a period of three years. Brennan accepted this, but Temperley demanded a further £10,000 for the delay, and after some argument the War Office agreed, also agreeing to pay Brennan a sizable salary to act as production chief. A scandal eventually blew up over this sum, which was wildly extravagant in comparison to the £15,000 paid for manufacturing rights to the Whitehead torpedo only 15 years previous.
The Brennan torpedo became a standard harbour defence throughout the British Empire and was in use for more than fifteen years. Operational stations were established in the UK at Cliffe Fort, Fort Albert on the Isle of Wight and Plymouth. Other stations included Fort Camden in Cork, Ireland, Lei Yue Mun Fort in Hong Kong and Forts Ricasoli & Tigne in Malta
In 1905 the Committee on Armaments of Home Ports issued a report in which they recommended the removal of all Brennan torpedoes from fixed defences due to their comparatively short range and the difficulty of launching them at night. Manufacture of the Brennan torpedo finished in 1906.[2]
The only remaining original Brennan Torpedo is exhibited at the Royal Engineers Museum in Chatham, Kent. However, traces of the installation at Fort Camden in County Cork are visible to this day.