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The invention of the gyrocompass was arguably more important than the invention of the present day Global Positioning System. At the tum of the century. the problem of magnetic compass error started to grow exponentially as Navy ships used more steel, generated more electric fields, and could shoot further. The problem was even worse for submarines. When submerged, a submarine’s only method of navigation was by dead reckoning. This made the submarine incapable of operating under the surface in restricted waters where they would be most effective. Even an extended underwater run in open water was a dangerous proposition.

The gyrocompass is key not only for navigation, but also for accurate fire control. The gyro is an integral part of a WWII submarine fire control system that includes the torpedo data computer, dead reckoning analyzer, dead reckoning racers, dummy log, pit log, sonars, and radar. This highly integrated system was years ahead of competitive systems and was one of the crowning achievements of WWII technology.

The Anschutz Company invented the first gyrocompass in 1906. After taking part in an Arctic expedition, Dr. Hermann AnschutzKaempfe (1872-1931) planned a 1902 expedition based on going to the North Pole in a submarine. He quickly learned that one of the major obstacles was navigation under the ice. He tried to build a gyrocompass in 1903 but found that there were many small forces that limited the usefulness of the device to only short periods. By 1906, Anschutz had formed a gyrocompass company. By 1908, the Anschutz Company had developed a device that worked well enough to pass sea trials on DEUTSCHLAND, the German fleet flag ship. Although the German compass worked, it was difficult to use, requiring careful calculations based on several tables that corrected for errors generated by the device. Even so, the fact that it was useable attracted the attention of navies throughout the world, including that of Elmer Sperry.

The Sperry automatic error-correcting gyrocompass was developed over the course of 12 months by the creative genius Elmer Sperry (October 21, 1860-June 16, 1939). In September of 1909 Sperry applied for his first of many gyrocompass patents (U.S. Patents No. 1,242,065, 1,279,471, and 1,255,480 – automatic error corrections).’ Although simple in concept, creating a practical gyrocompass is very difficult. Sperry had access to the erratic performance data on the Anschutz compass and focused on fixing the weak points of its design. By January of 1911, the Sperry compass was ready for sea trials. It is clear from the records that Sperry had the full support of the U.S. Navy during period, which did not want to buy gyrocompasses from Germany.

The Sperry system featured an automated limit on motion in the hird degree of freedom, and a servo feedback system based on an analog computer. This computer could automatically dampen and adjust out the errors generated by the changes in latitude and the ship’s pitching and rolling. These were major advancements over the Anschutz system, and the U.S. Navy quickly realized that they had the better navigation system. 2 For the first time in history it was possible to accurately determine a vessel’s location at all times, no matter what forces caused its motion. It worked in all weather, was less prone to local anomalies, and could be used no matter bow much steel was used to build the ship.

Elmer Sperry and his company held a monopoly on this critically important technology through its patents. Soon Anschutz developed its own servo based error correction mechanisms, and Sperry sued for patent infringement in 1914 in the international court at The Hague. 3 There is extensive correspondence between Sperry and his lawyers showing his deep personal interest in the progress of the case. 4 Unfortunately, by 1918 WWI had overtaken the infringement claims, making it impossible for Sperry to go any further with his legal claims.

At the end of WWI the U.S. Navy took the Anschutz gyrocompass technology from 9ermany as a prize of war. The Navy turned this technology over to the ARMA Corporation in an effort to create a competitor to Sperry. ARMA improved the Anschutz design with its own innovations and produced a gyro. Sperry then sued ARMA for the same infringements that the company had used to sue Anschutz. 6 The argument of Sperry being able to sue the Government for setting up ARMA in the gyrocompass business was taken from the Court of Claims all the way to the Supreme Court in Sperry vs. ARMA Number 239.

The Anschutz compass had several advantages over the Sperry design, most importantly the refinement of putting the gyro wheels at an oblique angle to each other. This approach was inherently more stable than the orthogonal Sperry arrangement. It allowed creating smaller, more accurate gyros. The trade off was that in order to read the course it was necessary to adjust the frequency of the wheels rotation based on the latitude. This adjustment was simple to implement and with uniquely ARMA improvements, a very fine gyrocompass was created.

The exact terms reached between the U.S. Navy, ARMA, and Sperry are not known except that all of the Navy gyrocompass business was divided between the two companies. ARMA remained in the gyrocompass business and Sperry remained the primary gyrocompass supplier. However, because of its critical importance to modem warfare, the Navy insisted on two suppliers. The same was true of the critical fire control equipment and stable elements.

The ARMA equipment was supplied to all submarines for several reasons. First it was inherently smaller, more stable and required less maintenance. Second, it was easier to adjust during operation. Third, it had lower power consumption. Lastly, it was easier to start and stop, an important advantage in a submarine that was trying to evade enemy acoustic detection. Surface ships used either type of equipment, but more Sperry equipment was installed. It is interesting that the very largest ships-aircraft carriers, battleships, and cruisers-received mostly ARMA gyrocompasses.

As the ARMA Corporation slowly decayed until it ceased to operate in 1976, support for the equipment underwent a consolidation among the third party vendors. Gyro Systems, Inc., a leader in the repair of this technology, slowly acquired the market of customers and inventories of parts and equipment until it remained as the last remaining center for ARMA gyros. The last of these gyros was removed from active service in the late 1980s.

The Current Status

Because ARMA was the Navy’s secondary supplier, fewer ARMA gyrocompasses were made and few of these have been saved.

USS PAMPANITO (SS 383), a Balao class (1943 built) submarine memorial and museum in San Francisco, is in a unique position to restore and preserve its original ARMA Corporation Mark VII gyrocompass. PAMPANITO was refit with the latest submarine fire control and navigation technology just before the end of the war and has received no post WWII upgrades or modifications. The National Maritime Museum Association’s preservation program’s goal is to make PAMPANITO as complete and as accurate as possible, striving for a summer 1945 configuration. Her torpedo data computer (the second most important part of the fire control system) is in the original WWII configuration and is the only one in the world that has been restored to operation, including its inputs from the gyro. (Editor’s Note: See Restoration of the me Mk Ill Aboard PAMPANITO on page 65 of the April 1995 issue of THE SUBMARINE REVIEW.) All necessary power systems have been restored. We have assembled all the other major components necessary to complete both the gyrocompass and the other components of the original WWII fire control system. We understand this system’s great historical significance and the need for its preservation. This project is of importance not just for PAMPANITO, but for the entire national historic naval ship fleet. Once documented, other ships will have the information needed to preserve their own gyros. Although perhaps 15 ARMA Mark VII gyrocompasses survive on historic naval ships, we know of no other museum currently capable of restoring and thereby preserving this technology.

On PAMPANITO, we believe that the operation of most types of equipment is a necessary component of a long term preservation plan for many reasons. First, idle equipment frequently deteriorates faster than operating equipment. The operation distributes lubrication, dries components, discovers incremental problems in their nascent stages, and avoids material creep. Second, although PAMPANITO has had no post WWII additions, modifications and removals did occur during the 1960s and 1970s when she was used as a reserve trainer and then opened for stripping by other Navy units. Consequently, wiring was modified and parts were removed from many systems on the boat. No system can be assured complete and accurately assembled until it has been operated at least once. Third, our experience has shown that many safety problems are found and corrected during the restoration of equipment to operational status. Fourth, in restoring equipment to operation, the skills of repair and operation are themselves preserved in a way not possible with static displays. Finally, operating equipment inspires respect and care not offered inoperable equipment. This is true not only of its caretakers, but also those that might be inspired by it. There is magic to teaching with a complete and operable system that is not possible with equipment of unknown condition. Of course, when long term operation is not sustainable, equipment is brought to operable state and then properly laid up.

The existing ARMA documentation does not sufficiently capture the process of setting up the sensitive element to a level that would allow repetition after the current generation of experts are gone. Servicing any mechanical gyrocompass has always been more an art than a science. The reason is that the forces at play to make the compass work are very small and are dependent on a delicate balance of all components to be expressed accurately. This is an apprenticed skill that has never been completely captured in writing. Among those servicing these gyros, craftsmen of greater skill were known and respected among their peers. Gyro Systems Inc. has two men still working who are skilled in the servicing of these gyros and all the specialized shop equipment. When they retire, and the shop dismantled, this art will be lost.

The Future

The PAMPANITO crew is planning the restoration of PAMPANITO’s ARMA Mk VII gyrocompass to operable condition. Preservation will enable the future study of not only the gyro on its own, but also integrated into the surprisingly sophisticated WWII fire control system. During educational programs it will be used to interpret navigation technology, principles of physics, and the principles of fire control. We serve over 200,000 visitors a year, including several thousand children in overnight programs.

We need your help to implement this plan. Through a combination of donation and purchase we have acquired the missing motor generators and amplifiers. Gyro Systems, Inc. has very generously donated all the spare parts we can use. Further, they still have all the shop tools, gauges, equipment, etc. needed to setup an ARMA gyrocompass sensitive element (the delicate rotor mechanism) and have offered the use of these facilities for free before they are dismantled. We were hoping to get a retired Navy chief to perform the 200 + hour shop job of setting up the sensitive element. Unfortunately family health problems have made this impossible. When we could not get the skilled labor for free, Gyro Systems offered to supply the skilled labor at their cost. These are the most qualified people available anywhere to perform this work and quite probably the only ones not yet retired. It is almost certainly the only properly equipped ARMA gyro repair shop intact. However, we still need to raise $20,000 to complete the project.

The NNMA is prepared to document, restore and preserve a fine example of WWII ARMA Mk VII gyrocompass. Outside of the extraordinary technology of this device, the ARMA gyrocompass has a special place in history. But we must act now while the craftsmen are still available to document the sensitive element setup. If you can help, please contact the authors at:

Pier 45
San Francisco, CA 94129
Phone: (415) 775-1943
Fax: (415) 441-0365


1.Elmer Sperry, Inventor and Engineer, by Thomas Parke Hughes, 1971, Johns Hopkins Press, Chapter 5.

2.Bulletin of Information No. 1002, Sperry Gyroscope Company, 1912.

3.Letter from the Sperry Gyroscope Company to Elmer Sperry, May 28, 1914. “Your letter No. 265 of May 16111, in regard to patents and the Anschutz infringement suit has been carefully gone over with everybody here that can be of assistance in getting together the information. … I shall try to get this matter as far along as possible before you return and shall be glad of any further suggestions in regard to matters that we can take care of for you.”

4.All references on this page are reproduced with the permission of the Hagley Museum and Library, Wilmington, DE 19807.

5.Letter to Elmer Sperry from the U.S. Department of State, December 18, 1916.

6. lnter-Office Memorandum, from H.H. Thompson (Esq.) to E.A. Sperry, May 21, 1923. uThe Legal Department would like instructions concerning the proposed suit in the Court of Claims on account of the ARMA Compass. There is no doubt that such a suit could be lodged at this time.”

7.Memorandum of the Opinion of the Supreme Court in Sperry Vs ARMA. Number 239.

8. ARMA Corporation. Copyright 1943, ARMA Corporation Company History, pages 6-7. uThe Navy was so impressed with the record the Company had made with the searchlights that it took David M. Mahood and Arthur P. Davis into its confidence explaining that a delicate situation had arisen in the Gyroscopic Compass field and asked if they could develop, at their own expense. a compass with a design different from that being produced by another company already in the field.” Caption on picture of same page: “the USS PILLSBURY. the first ship to carry ARMA Compass Equipment (US Navy Official Photo).

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