Anschütz-Kaempfe Invents the First Practical Gyrocompass

Date 1906

Hermann Anschütz-Kaempfe designed and manufactured the first practical gyroscopic compass, a device capable of detecting changes in the orientation of a moving vehicle, which greatly enhanced navigation at sea.

Locale Kiel, Germany

Key Figures

• Hermann Anschütz-Kaempfe (1872-1931), German inventor and manufacturer
• Léon Foucault (1819-1868), French experimental physicist
• Elmer Ambrose Sperry (1860-1930), American engineer and inventor

Summary of Event

The invention of the gyroscopic compass, or gyrocompass, a major step in the development of modern navigational instrumentation, followed naturally from the revolutionary progress in transportation technology that took place during the nineteenth century. Although complex in mathematical detail, the principle of gyroscopic motion is intuitively easy to grasp and to demonstrate. A spinning body such as a wheel tends to retain its orientation with respect to the two axes perpendicular to the plane of rotation, the force required to change its orientation being proportional to the angular momentum of the spinning body. Furthermore, when a disturbing torque is applied, the spinning body reacts by slowly rotating (precessing) in a direction at right angles to the direction of the torque.

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 Frisbees 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. One can get a qualitative impression of the characteristics and strength of gyroscopic force by causing a detached bicycle wheel to rotate rapidly in the vertical plane, then, while holding it, attempting to tip it sideways and to turn in place. Both motions are surprisingly difficult, although there is no impediment to walking in a direction parallel to the spinning wheel.

In 1852, the French inventor Léon Foucault built the first gyroscope, a measuring device consisting of a rapidly spinning wheel 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, as the spinning wheel, which was not fixed, retained its orientation in space while the earth turned 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 precess 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. It differs from a magnetic compass in two important ways: It operates independent of the earth’s magnetic field and any magnetic disturbances in the immediate surroundings, and it designates true north (the earth’s axis) rather than magnetic north. Foucault also developed a mathematical analysis of gyroscopic forces. The gyroscope attracted immediate attention as the demonstration of an interesting physical principle and as a popular children’s toy.

Gyroscopic forces act to some extent in any moving object with spinning parts; with the development of motorized transportation systems, the magnitude of these forces increased dramatically and became important in vehicle engineering. In bicycles and paddle-wheel steamers, the wheels are oriented so as to act as stabilizers. In early automobiles, the flywheel had to be reoriented when it was discovered that the original orientation inhibited steering. (Unlike a train or steamship, an automobile is constantly changing direction, and gyroscopic forces that tend to keep the vehicle moving in a straight line are undesirable.) It became evident that the gyroscopic properties of spinning wheels could be used to advantage in designing vehicles that would resist tilting. In 1906, Otto Schlick patented a design for a gyroscopic stabilizer for steamships in which the stabilizing properties of a rapidly spinning horizontal wheel were used to reduce the pitch and roll of a ship. From 1908 to 1910, Louis Brennan attracted attention with a prototype monorail balanced by an internal gyroscopic stabilizer.

The ability of a gyroscope to resist deflection is also useful in sensors that detect when a moving object changes course. This property formed the basis for a simple German device (patented in 1898) for keeping a torpedo on course. When the torpedo was set in motion, a rotor was activated simultaneously; if the course of the torpedo changed sufficiently, the rotor exerted pressure on the valve controlling the compressed-air propellant on that side, creating an asymmetrical propulsion force sufficient to turn the torpedo back toward its original course. More sophisticated gyroscopic deflection sensors were installed in the World War II era in V-l and V-2 rockets and in early guided missiles. These sensors communicated with ground bases by radio, enabling navigators on the ground to plot and correct missile courses.

From 1904 to 1905, Hermann Anschütz-Kaempfe, a German manufacturer working in the Kiel shipyards, became interested in 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 instrumentation designed for surface vessels. A submarine 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 was logical for Anschütz-Kaempfe to turn to the gyroscopic effect to produce an instrument that would both designate true north and sense changes in the submarine’s orientation. Although simple in principle, production of a gyroscopic compass that would function accurately on a moving ship posed significant engineering problems; namely, the device 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 being strong enough to withstand the inevitable pitching and rolling of a ship at sea), and it needed a continuous power supply to keep the gyro rotating at high speed.

The original Anschütz-Kaempfe gyrocompass consisted of a pair of spinning wheels connected by an electric motor. This apparatus was suspended via a shaft from a float consisting of a hollow ring immersed in mercury, which allowed free rotation around the axis of the shaft and also served as one electrical contact for the motor. Reorientation around this shaft enabled the axis of the spinning gyroscope to orient itself along the earth’s axis. The shaft was connected to a compass card visible to the ship’s navigator. Motor, gyroscope, and suspension system were enclosed in a set of gimbals that permitted the apparatus to retain its vertical orientation with respect to the earth despite the pitch and roll of the ship. Later versions introduced an electromagnet to correct for the latitude and direction of motion of the ship. In 1912, Anschütz-Kaempfe and Max Schuler introduced a model with three rotors mounted in an equilateral triangle; this model was less subject to error on a rolling ship and was the principal type used on German submarines during World War I.

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.

Although these developments took place against a background of increasing international tension that culminated in World War I, the Anschütz Gyrocompass Company was a private commercial venture that obtained international patents. No shroud of military secrecy obscured the development of the first gyrocompass, although subsequent refinements, both in Germany and in the United States, were subject to wartime restrictions on strategic information.

Elmer Ambrose Sperry, a New York inventor who was intimately associated with pioneering 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, and the suspension system eliminated some problems associated with drag and turbulence in the mercury trough used in the suspension system of the Anschütz-Kaempfe compass. The Sperry gyrocompass was in use on larger American battleships and submarines on the eve of World War I.

Significance

Both the German and the American naval authorities recognized that the gyrocompass was a valuable navigational tool and were quick to undertake a program of installing the compasses on major submarines and surface vessels. The ability to navigate submerged submarines was of critical strategic importance in World War I, when submarine warfare first played a major role in war at sea. 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 shipping by the Allied Powers, and, although German efforts to blockade England and France were ultimately unsuccessful, the tremendous toll inflicted by the U-boats 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.

Related gyroscopic devices sensing pitch (vertical movement of nose relative to tail), roll, and yaw (horizontal deviations of nose relative to tail) became important in aircraft instrumentation. A World War I-era aircraft pilot had less need of the compass function of a gyroscope than did a submarine captain because the pilot could depend on landmarks for orientation, but a device giving rapid feedback on changes in orientation by the aircraft was a distinct advantage in a battle.

Gyrocompasses were standard equipment on submarines and battleships, and, increasingly, on larger commercial vessels during World Wars I and II and the period between the wars. Although refinements were incorporated that made the compasses more accurate and easier to use, the fundamental design differed little from that invented by Anschütz-Kaempfe. Gyroscopic sensors detecting deviations from course were part of the equipment of the German V-1 and V-2 rockets and guided missiles.

Two additional devices employing gyroscopic principles are the laser gyroscope and the nuclear magnetic resonance gyroscope. The former employs two laser beams traveling in opposite directions within a rapidly spinning mirrored cavity; differences in the apparent velocity of light in the beam traveling in the direction of spin relative to the beam traveling in the opposite direction produce a change in wavelength, which in turn is used to measure changes in rotational angle. A nuclear magnetic resonance gyro functions because individual atomic nuclei spin; this spin produces the magnetic moment of the nucleus, and externally applied magnetic fields act on spinning nuclei in a manner analogous to the effects of gravity and mechanical deflection on a conventional gyroscope.

Conventional gyrocompasses continue to be used extensively in marine navigation, and gyroscopic deflection sensors are part of the standard instrumentation of modern aircraft, which are typically equipped with three spring-mounted gyroscopic rotors to detect the amount and speed of deflection in three dimensions. One gyroscopic rotor design suspends the spinning element electrostatically, eliminating drag from mechanical suspension elements. The technology pioneered by Anschütz-Kaempfe and Sperry has enjoyed enduring practical application.

Bibliography

Collins, A. Frederick. “The Gyroscope as a Compass.” Scientific American 96 (April 6, 1907): 294-295. Reports the development of the Anschütz-Kaempfe gyrocompass, with detailed descriptions of the design of the device, illustrations of a preliminary and improved model, and an account of field testing performed by the German navy in 1906 and 1907.

Crabtree, Harold. An Elementary Treatment of the Theory of Spinning Tops and Gyroscopic Motion. London: Longmans, Green, 1914. A general reference; gives a good perspective on the increasing importance of gyroscopic motion and devices employing it during the early years of the twentieth century. Includes a simple introduction to the theory of the gyroscope and detailed descriptions of the Anschütz-Kaempfe and Sperry gyrocompasses, the Schick gyroscopic stabilizer, the Brennan monorail, and gyroscopic forces in motor vehicles.

Demel, Richard F. Mechanics of the Gyroscope. New York: Macmillan, 1929. An engineering text that explains the theory of the gyroscope and the theory and construction of gyroscopic devices in some detail. Covers both the Anschütz-Kaempfe and Sperry gyrocompasses and the differences between them, with more attention given to the Sperry model. Extensive mathematical treatment of precession errors.

“The New Navy Gyroscopic Compass.” Scientific American 106 (June 29, 1912): 588-589. A clear account, with diagrams, of the Sperry gyroscopic compass. Includes a nonmathematical description of the operation of the device and a discussion of the difficulties of using conventional compasses in early twentieth century submarines and battleships. Useful for visualizing the contemporary impact of the discovery of a practical gyroscope.

Parson, N. A. Guided Missiles. Cambridge, Mass.: Harvard University Press, 1958. A nontechnical introduction to guided missiles; includes a section on how a gyroscope functions as a steering device in a radio-controlled flying object.

Rawlings, A. L. The Theory of the Gyroscopic Compass and Its Deviations. New York: Macmillan, 1944. A textbook designed for the engineers of firms manufacturing gyrocompasses and for shipboard personnel responsible for using and maintaining them. Contains diagrams and descriptions of the Anschütz-Kaempfe gyrocompass and its modifications.

Tall, Jeffrey. Submarines and Deep-Sea Vehicles. San Diego, Calif.: Thunder Bay Press, 2002. Highly illustrated history of submarines. The first chapter discusses the pioneers who built and sailed in undersea vehicles, including those who contributed to the technology of navigation. Includes bibliography and index.