Brennan Torpedo

Brennan torpedo
Brennan torpedo replica at the Hong Kong Museum of Coastal Defence; cut-out shows the two drums of wire used for propulsion and guidance
Type	Torpedo
Place of origin	Australia
Service history
In service	1890-1906
Used by	British Army Royal Engineers
Production history
Designer	Louis Brennan
Designed	1874-1877
Manufacturer	Brennan Torpedo Company
Specifications
Length	15 feet (4.6 m)
Effective firing range	2,000 yards (1,800 m)
Warhead weight	200 pounds (91 kg)
Engine	Shore-based steam winch
Maximum depth	12 feet (3.7 m)
Speed	27 knots (14 m/s)
Guidance system	Wire
Launch platform	Shore-based harbor defense installations

The Brennan torpedo was a torpedo patented by Irish-born Australian inventor Louis Brennan in 1877. It was propelled 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".

The Brennan torpedo was similar in appearance to more modern ones, apart from 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.