Brennan and his gyroscope railroad, New York, no date given. Louis Brennan (January 28, 1852 - January17, 1932) was an Irish-Australian mechanical engineer and inventor. Brennan invented the idea of a steerable torpedo in 1874, from observing that if a thread is pulled on a reel at an angle with suitable leverage, the reel will move away from the thread side. Brennan went to England in 1880 and brought his invention before the War Office. In 1887 Brennan was appointed superintendent of the Brennan torpedo factory, and was consulting engineer 1896-1907. He did much work on a monorail locomotive which was kept upright by a gyrostat. In 1903 he patented a gyroscopically-balanced monorail system that he designed for military use. From 1916 to 1919 Brennan served in the munitions inventions department. From 1919 to 1926 he was engaged by the air ministry in aircraft research work at the Royal Aircraft Establishment and gave much time to the invention of a helicopter. The government spent a large sum of money on it, but in 1926 the air ministry gave up working on it. In January 1932 he was knocked down by a car in Switzerland, and died several days later at the age of 79.