09 July 2009
The invention: The first practical navigational device that enabled ships and submarines to stay on course without relying on the earth’s unreliable magnetic poles. The people behind the invention: Hermann Anschütz-Kaempfe (1872-1931), a German inventor and manufacturer Jean-Bernard-Léon Foucault (1819-1868), a French experimental physicist and inventor Elmer Ambrose Sperry (1860-1930), an American engineer and inventor From Toys to Tools A gyroscope consists of a rapidly spinning wheel mounted in a frame that enables the wheel to tilt freely in any direction. The amount of momentum allows the wheel to maintain its “attitude” even when the whole device is turned or rotated. These devices have been used to solve problems arising in such areas as sailing and navigation. For example, a gyroscope aboard a ship maintains its orientation even while the ship is rolling. Among other things, this allows the extent of the roll to be measured accurately. Moreover, the spin axis of a free gyroscope can be adjusted to point toward true north. It will (with some exceptions) stay that way despite changes in the direction of a vehicle in which it is mounted. Gyroscopic effects were employed in the design of various objects long before the theory behind them was formally known. A classic example is a child’s top, which balances, seemingly in defiance of gravity, as long as it continues to spin. Boomerangs and flying disks derive stability and accuracy from the spin imparted by the thrower. Likewise, the accuracy of rifles improved when barrels were manufactured with internal spiral grooves that caused the emerging bullet to spin. In 1852, the French inventor Jean-Bernard-Léon Foucault built the first gyroscope, a measuring device consisting of a rapidly spinning wheel mounted within concentric rings that allowed the wheel to move freely about two axes. This device, like the Foucault pendulum, was used to demonstrate the rotation of the earth around its axis, since the spinning wheel, which is not fixed, retains its orientation in space while the earth turns under it. The gyroscope had a related interesting property: As it continued to spin, the force of the earth’s rotation caused its axis to rotate gradually until it was oriented parallel to the earth’s axis, that is, in a north-south direction. It is this property that enables the gyroscope to be used as a compass. When Magnets Fail In 1904, Hermann Anschütz-Kaempfe, a German manufacturer working in the Kiel shipyards, became interested in the navigation problems of submarines used in exploration under the polar ice cap. By 1905, efficient working submarines were a reality, and it was evident to all major naval powers that submarines would play an increasingly important role in naval strategy. Submarine navigation posed problems, however, that could not be solved by instruments designed for surface vessels. Asubmarine needs to orient itself under water in three dimensions; it has no automatic horizon with respect to which it can level itself. Navigation by means of stars or landmarks is impossible when the submarine is submerged. Furthermore, in an enclosed metal hull containing machinery run by electricity, a magnetic compass is worthless. To a lesser extent, increasing use of metal, massive moving parts, and electrical equipment had also rendered the magnetic compass unreliable in conventional surface battleships. It made sense for Anschütz-Kaempfe to use the gyroscopic effect to design an instrument that would enable a ship to maintain its course while under water. Yet producing such a device would not be easy. First, it needed to be suspended in such a way that it was free to turn in any direction with as little mechanical resistance as possible. At the same time, it had to be able to resist the inevitable pitching and rolling of a vessel at sea. Finally, a continuous power supply was required to keep the gyroscopic wheels spinning at high speed. The original Anschütz-Kaempfe gyrocompass consisted of a pair of spinning wheels driven by an electric motor. The device was connected to a compass card visible to the ship’s navigator. Motor, gyroscope, and suspension system were mounted in a frame that allowed the apparatus to remain stable despite the pitch and roll of the ship. In 1906, the German navy installed a prototype of the Anschütz- Kaempfe gyrocompass on the battleship Undine and subjected it to exhaustive tests under simulated battle conditions, sailing the ship under forced draft and suddenly reversing the engines, changing the position of heavy turrets and other mechanisms, and firing heavy guns. In conditions under which a magnetic compass would have been worthless, the gyrocompass proved a satisfactory navigational tool, and the results were impressive enough to convince the German navy to undertake installation of gyrocompasses in submarines and heavy battleships, including the battleship Deutschland. Elmer Ambrose Sperry, a New York inventor intimately associated with pioneer electrical development, was independently working on a design for a gyroscopic compass at about the same time. In 1907, he patented a gyrocompass consisting of a single rotor mounted within two concentric shells, suspended by fine piano wire from a frame mounted on gimbals. The rotor of the Sperry compass operated in a vacuum, which enabled it to rotate more rapidly. The Sperry gyrocompass was in use on larger American battleships and submarines on the eve ofWorldWar I (1914-1918). Impact The ability to navigate submerged submarines was of critical strategic importance in World War I. Initially, the German navy had an advantage both in the number of submarines at its disposal and in their design and maneuverability. The German U-boat fleet declared all-out war on Allied shipping, and, although their efforts to blockade England and France were ultimately unsuccessful, the tremendous toll they inflicted helped maintain the German position and prolong the war. To a submarine fleet operating throughout the Atlantic and in the Caribbean, as well as in near-shore European waters, effective long-distance navigation was critical. Gyrocompasses were standard equipment on submarines and battleships and, increasingly, on larger commercial vessels during World War I, World War II (1939-1945), and the period between the wars. The devices also found their way into aircraft, rockets, and guided missiles. Although the compasses were made more accurate and easier to use, the fundamental design differed little from that invented by Anschütz-Kaempfe.