Mr. Merrill is a frequent contributor to THE SUBMARINE REVIEW and is a published author of several books on the history of undersea technology. He is a retired engineer with lengthy experience at the New London Lab of the Naval Undersea Wa1fare Center. He currently lives in Waterford, CT.
Loran, a World War II navigation system fulfilling wartime all weather needs with a near global coverage and importance to the war effort, was devised, tested, and broadly implemented within a period of less than four years. The destruction of Allied ships in the North Atlantic gave rise to the crash program to create the navigation system. It is still a system of importance in the new century.
This paper addresses the question, “Why and how did Loran happen?” To this end, background, events, and highlights are examined during the twenty-four months of research and development preceding the official transfer of the system to the Navy on January 1, 1943.
Loran was a concept and proposal in late 1940; the investigative system research was virtually completed by September 1941.’ In 1942, the first Loran system operating at 1950 kHz was in use along the Northeast Atlantic Coast, providing long distance ship and aircraft navigation.
Extensive system implementation started in 1943. At the end of the war in 1945 at least 75,000 receivers and 100 transmitters were installed and 2,500,000 Loran charts distributed to all services. The charts from the Navy Hydrographic Office included fifty million square miles of the earth’s surface.2 About 70 stations had been installed, offering nighttime service over 30 percent of the surface of the earth, principally the most trafficked Atlantic waterways and nearly the entire Pacific. Up to July 1945, $71,000,000 worth of Loran equipment was delivered to the services.
After World War II
Loran was one of the three original projects’ at the MIT Radiation Laboratory sponsored in 1940 by the National Defense Research Committee (NDRC). In the years following WWII, development continued under the aegis of the United States Coast Guard (USCG), to provide air, land and sea navigation for the military, for maritime interests and for the airline industry. The Korean, Vietnam, and Cold Wars again gave opportunity for Loran use in a variety of geographical areas. Technological advances involving satellites and missiles arose in the late 1950s, requiring navigational needs that were met with Loran C operating in the VLF spectrum ( l OOkHZ). The Navstar/GPS system would later employ Loran’s method of using time difference in the arrival of radio signals to calculate position.
Lorants Relevance in 2005
More than sixty years after Loran beginnings, the navigation system is still worldwide with additional potential value in the future to meet new needs. This is substantiated in an article appearing in the European Journal of Navigation in December 2003 asking”Is Loran-C the answer to GPS vulnerability?”
Loran’s Capabilitv to Mitigate the Impact of GPS Outage on GPS Position. Navigation, and Time Applications is the title of a December 2004 evaluation of eLoran (enhanced Loran) to address GPS backup. The article represents the findings of industrial and government organizations.
The Loran system allows a vessel or aircraft to determine its position in all weathers and at great distances from shore. A radio wave is sent from a master station and received by the ship or plane and slave stations. On receipt of the pulse, the slave sends out its pulse, which is also received by the vessel or plane. The ship or plane Loran receiver-indicator measures electronically the difference in time of arrival of the radio waves from a ground station. Using Loran charts for the area served by the ground stations, a line of position is determined from the time difference. A second line of position is determined from another pair of stations. The intersection of the two lines provides a fix.
Measuring the time of arrival of radio waves aboard a ship, aircraft, or fixed shore station immediately created an additional and diverse number of new challenges regarding how radio waves propagate over the various signal paths as well as a precise measurement of time. The signal propagation aspects were particularly demanding, as details relevant to the concept were not available. Further, system engineers were confronted with the design requirements for new receiving and transmitting equipment. Receivers suited for land, sea and air placed further demands. It should be noted that the ongoing war created severe time constraints on expediting the development and later implementation of the system on a nearly global basis.
World War I was fought primarily with weapons and equipment available at its start. Within a year of the start of World War II, demands for new devices, weapons and systems presented broad challenges to the United States scientific and engineering community to meet the needs of England and France as well as the United States.
Response to the challenges, sometimes referred to as the physicists and engineers’ war, witnessed a continuing stream of new and frequently complex weapons and systems. It is important to point out that the theoretical information and the technologies available to work with were primitive compared to those at the end of the 20’h century. The technological advances made during the war years probed and pushed the boundaries of science and engineering forward.
The MIT Radiation Laboratory in Cambridge, Massachusetts, was the founding place of Loran. Overall in five years from 1940 to 1945, the broad accomplishments of the Radiation Laboratory, especially in radar (microwaves), have been said to be equal to twenty-five years of progress. Loran, a new and better aid to navigation, using 1950 kHz was unique at the successful Radiation Laboratory devoted primarily to radar.
Not unlike other scientific and engineering developments of the 20•h Century, Loran evolved and attained global coverage by the effort and skills of many. Likewise, success of the MIT Radiation Laboratory rests on the talents at the Cambridge site, while industry’s role is equally notable.
The story of Loran development and implementation quickly brings to mind Vannevar Bush, James B. Conant, Alfred Loomis, John Alvin Pierce, Richard Woodward, Admiral Julius A. Furer USN, Captain Lawrence M. Harding USCG, Melville Eastham, and others whose contributions to the new systems were substantial.
It should be stressed that beyond the laboratory and industrial production, thousands of civilian and military personnel (heavily USCG) made system implementation possible under the most arduous wartime conditions in impossible geographical locations topped by severe logistic demands. The classification of Loran as Secret was a further challenge to be met during the war years. After the war, the classification was removed.
The aforementioned scientists and engineers provide the milestones for the narrative. Considering the events surrounding Loran in the 21’1 Century loses the anxiety, urgency and importance of the moment in late 1940 when the roots of Loran were fonned.
On 15 June 1940, the time of the fall of France, President Franklin D. Roosevelt approved the establishment of the National Defense Research Committee (NDRC) under the leadership of Vannevar Bush. Earlier in May, Bush proposed to President Roosevelt the concept of NDRC to coordinate, supervise, and conduct scientific research for war purposes except for flight. The presidential letter appointed the twelve members of the Committee and selected Bush as chainman. The NDRC was established on 27 June 1940 under the National Defense Act of 1916.
Bush, dean of engineering at MIT from 1932-38 and in 1940 President of the Carnegie Institution of Washington, spearheaded all the significant World War II scientific efforts and accomplishments of the war years. His goal was scientific research towards the creation of new military tools and techniques. The NDRC worked in close liaison with the military but independent of its control.
Bush’s World War I antisubmarine warfare research experiences in 1917-18 demonstrated to him the need for independence in pursuing scientific and engineering work with the military. This was not lost as he organized the national scientific and engineering resources in 1940 to meet the new Gennan threat. Cooperation between military, scientific and industrial communities does not always prevail.
Alfred L. Loomis
Attention to Alfred L. Loomis, mentioned above, is essential to the Loran narrative. Loomis has sometimes been referred to as the last great amateur of science. His scientific and engineering experience in the period up to World War II included much of the leading technology of the mid-201h Century. Precise time measurement, microwaves, cyclotron investigation and development, and medical advances were only a part of his experience. In addition, during the 1930s, his personal laboratory that he funded and staffed at Tuxedo Park near New York City included national and international visitors from across the science and engineering spectrum. Microwave studies, later critical to radar, comprised one aspect of the ongoing work at his laboratory.
Loomis was equally at home in the world of academic science at the University of California in Berkeley, California; at MIT at Cambridge, Massachusetts; and on the Washington scene. His achievements on Wall Street in the 1920s provided him with the means to pursue and independently support his scientific interests. In early June 1940, Bush appointed Loomis to be the head of the NDRC Microwave Committee. In the following months, Loomis had full involvement with the Tizard Mission.
The Tizard Mission
Henry Tizard, an English scientist and administrator started in January 1935 with a small committee to address using advances in science and technology to strengthen defense against hostile aircraft. The timely and quick response of his committee brought a December 1935 British government sanction to build the first five radar stations, initially known as Radio Detection Finding (RDF), to detect hostile aircraft. By September 1939, all the radar stations were manned and ready for action.
It became abundantly clear to England, after ten months of war, a newly-surrendered France, and the successful U-boats, that the need for technical superiority plus productive power was essential. England turned toward the United States.
Churchill, becoming Prime Minister in May 1940, supported the concept of a technical exchange with the United States. Most of England’s secret war-related technical developments were to be included in the exchange. In August 1940, with the support of Churchill and Roosevelt under Tizard’s leadership, the mission (formally called The British Scientific and Engineering Mission to the United States) arrived in Washington to encourage cooperation and share technical knowledge. It was anticipated that even with United States neutrality its industry would develop and produce the British technical secret.
Detailed sharing of scientific and technical knowledge of wartime developments of weapons and equipments between the two countries had not occurred. The mission’s success turned out to be a major event in part because the personnel in Tizard’s British mission included a mixed team of scientists and serving officers from Army, Navy and Air Force with battle experience to interface with the United States armed services and others in Washington. The goal of the mission was to provide a basis to develop and build new weapon systems enhanced by the technical exchange. Previously, the neutrality of the United States was a factor that inhibited England’s interest in a scientific exchange. British documentation on all the classified wartime developments included books, manuals, circuit diagrams, blueprints, films and notes. The 9.5 cm cavity resonant magnetron, developed early in 1940, provided a powerful source of microwaves and became the cornerstone of a number of United States-designed radars in the following five years. This mission and the technical information exchange in the late summer and early fall of 1940 provided the United States with what turned out to be a sixteen-month window of preparation before December 7, 1941.
At the time of the Tizard Mission visit to the United States, it was understood that aircraft bombing of fixed land targets and aircraft hunting enemy submarines needed precise information about their own location. Britain’s long range bombing in Europe was constrained because of lack of an aircraft navigation system with a reach into central Europe. It should be noted that in 1937, a British navigation line of sight system providing latitude and longitude was proposed. Location of a ship or aircraft was determined by the time difference of arrival of radio signals (20 to 85 MHz) received from two or more fixed transmitters. Development of the secret system called Gee (short for Grid) began in 1940.
Relevant to this, Tizard put forward his opinion that North America was the ideal place to work on the development of a long-range navigational system because of the ongoing hostilities in Britain precluded testing. At that time, the desired system independent of weather conditions should have a range of 1000 miles or greater with an accuracy of the order of 5 miles.
MIT Radiation Laboratory: A Sixteen-Month Head Start
The environment for the exchange was enhanced by the newly formed NDRC under Vannevar Bush with his knowledge and workings of the American scientific academic and industrial community. On October 16, 1940, shortly after the meetings with the Tizard Mission, the NDRC contracted with MIT• to be the site for the Radiation Laboratory (Rad Lab) to pursue radar in various forms and to implement the recently-developed British magnetron capable of creating powerful microwaves. The first Rad Lab staff meeting was held November 11, and the first assignment on that date was to design and improve night-fighter radar. ‘0 Officially, the Radiation Lab operated from October 1940 until December 31, 1945.
By March 1941 there were 90 scientists and engineers at work. Late in 1942, the Rad Lab budget reached more than one million dollars; the staff was close to two thousand and in 1945 near four thousand with one-quarter academics and about five hundred of them physicists.11 R&D in Radar was the primary focus of the Rad Lab.
All the work at the Rad Lab was at the secret level during the pre-war and war years. This requirement placed another level of difficulty on the efforts.
OCTOBER 1940-JUNE 1942
At its meeting on October I, 1940, the Anny Signal Corps Technical Committee established requirements for a “Precision Navigational Equipment for Guiding Airplanes.”
In view of the above and the recent the consideration of Gee by members of the Tizard group, in October 1940 chairman Loomis of the Microwave Committee proposed a pulsed hyperbolic ultra high-radio frequency system (30-40 MHz) to meet the Signal Corps requirements. The eventual system at a much lower frequency provided an accuracy of one percent at range of one thousand miles. Research on the systems started immediately by members of the Microwave Committee. In addition to being a strong influence on the Loran group, Loomis provided his personal financing to the early project awaiting government support. In 1959, Loomis was awarded the patent for Loran Long Range Navigation System.
By early spring 1941, the task to investigate this approach was transferred to the MIT Radiation Laboratory with government support. As it was the third Laboratory assigned task, it was referred to as Project III. Initially, the research was identified as LRN for Long Range Navigation (and on occasion Loomis Radio Navigation). The full time navigation group evolved at the Radiation Laboratory under the direction of Melville Eastham, President of the General Radio Company, on leave from Harvard. The starting team of four or five grew to about 30 by 1943.
Initial Loran Efforts
A committee that included members of large electronic companies and the Radiation Laboratory personnel met on December 20, 1940 13 and arranged for the procurement, installation, and field-testing of one pair of transmitting stations and navigation equipment proposed by Loomis.14 Ranges of300 to 500 miles for high-flying aircraft were anticipated. At the time of this early procurement, the design and planning included a system operating in the UHF spectrum at frequencies of the order of 30MHz.
|Bell Laboratories||2 crystal controlled timers|
|General Electric||I 1.5-mcgawatt transmitter|
|RCA||6 high frequency pulse triode transmitting tubes|
|Sperry||2 receiver-indicators (independent design)|
|Westinghouse||I 2.5 megawatt transmitter|
Sites for the system’s transmitter testing were made available March 24, 1941 when the Radiation Laboratory received permits from the Treasury Department to use two inactive USCG lifeboat stations. One lifeboat station was located at Montauk on Long Island, New York and the other at Fenwick Island, Delaware. These stations provided a 209-mile baseline and were within a reasonable distance of the Bell Telephone Laboratories, the project coordinator. By June 1942, both experimental transmitter sites were operating. These early negotiations eventually in 1942 brought the Coast Guard into the Loran development effort. The Coast Guard’s Loran role became important, broad and intensive during the World War II years and beyond.
After system analysis, laboratory and fieldwork, interest in the UHF (30 MHz) part of the radio spectrum waned. One of the system goals was to have navigation coverage of the North Atlantic maritime routes. UHF signal propagation coverage was inadequate. By mid-spring 1941, frequencies of the order of2000 KHz offered coverage advantages and other attributes.
John Alvin Pierce
Pierce, 16 at Harvard Cruft Laboratories from the early 1930s, was experienced in radio propagation, including ionosphere pulse sounding. This aspect of radio wave propagation was critical to the evolving navigation system. On July 1, 1941, at the time when testing of the first hyperbolic radio aid to navigation was about to begin, he took leave from Harvard and worked for nearly five years at the MIT Radiation Laboratory with the navigation system team. His broad and important participation in the Loran development included determining the range of pulsed radio waves when reflected off the lower or E-Layer of the Heaviside layer.
While attending Radiation Laboratory navigation team meetings prior to leaving Harvard, Pierce designed and had constructed a pair of S kW 2000 kHz pulse transmitters. The lower frequency transmitters were installed for testing at the Delaware and Long Island former USCG stations.
Propagation tests were made between September 3 and 22, 1941. The main receiving station was set up in the Ann Arbor, Michigan home of a University of Michigan professor. Pierce installed receiving equipment in a station wagon and made signal measurements at Springfield, Missouri and Frankfort, Kentucky. The tests indicated the possibility of stable sky-wave transmission. A range of 1000 miles with the low power transmitters and the ground wave range proved greater than expected. As a result, the work at UHF was abandoned before the delivery of much of the equipment on order.
Pierce emphasized in his report of the measurement trip the need for an improved method for reading time difference. During the next several months, efforts by the Radiation Laboratory navigation team developed a trace cathode ray tube indicator capable of a I microsecond measurement and a multiple trace for pulse matching the signal from the master and slave stations. Direct synchronization at lower frequencies was also achieved.
Hz long-range signal measurements in Bermuda. Satisfactory ground waves from the S KW transmitters were measured at a range of about 720 miles. Importantly, these tests established the practicability of nighttime sky waves from the E layer of the ionosphere. After further enhancement to transmitter performance, 1950 KHz was adopted as the frequency of interest.
Admiral Julius A. Furer
At the outbreak of World War II, Admiral Furer became the Coordinator of the Research and Development and the senior member of the NDRC. He coordinated widespread research that sped development of modem weapons systems for the Navy. These services won Furer the Legion of Merit on 30 June 1945. Based on the results of the navigation system testing, Furer felt that a navigational aid might be developed.20 His support, together with that of others, helped to bring about this practical long-range navigation system to aid in the war effort.
In late March 1942, signal test results at 2000 kHz showing significant ground wave coverage and improved cathode ray tube presentation of the signals led Melville Eastham to present the results of this ongoing laboratory and fieldwork to representatives of the Joint Chiefs of Staff. He also proposed a series of tests along the Atlantic seaboard to determine maximum range and the possible development of an aid to navigation.
The plan was to construct a chain of stations installed and operated by NORC. with results to be submitted to those most interested. The Army showed little or no interest, and Admiral Furer suggested that the Radiation Laboratory carry out the plan and keep him apprised.21 The test sites would be located along the United States and Canadian Atlantic coasts. In the middle of May 1942, Canada agreed to cooperate and with two sites in Nova Scotia complementing the two United States sites. This was a beginning.
Admiral Furer, observing the evolving long range navigation system, felt that Navy guidance and assistance should be available to the ongoing research at the Radiation Laboratory. Further, an emerging aid to navigation system in the future would come under the USCG. In keeping with this and mindful of the Coast Guard ongoing responsibility for United States Aids to Navigation, with support from Captain F. R. Furth of the office of VCNO, Captain Lawrence M. Harding USCG was assigned as Navy liaison officer in the development and implementation of the navigation system. He was assigned as naval representative for Loran to the Radiation Laboratory and to undertake any necessary field activities.
Captain Harding, formerly of the U.S. Lighthouse Service, was deeply experienced in marine radio beacon technology. The future jurisdiction and administration of Loran by the USCG stemmed from this early and increasing wartime involvement with the evolving navigation system. Intensive and broad participation characterizes the role of the USCG through the WWII years and beyond. Because of Loran’s utmost secrecy, Harding’s orders to temporary duty at Cambridge, Massachusetts were unknown to his immediate supervisors. It is interesting that Harding became responsible for the system designation acronym Loran (Long Range Navigation).
With the 100 kW transmitters installed and tested in June 1942, it was important to determine as quickly as possible whether Loran had practical and immediate value to the war effort; Harding initiated a month long sea test on the Coast Guard weather ship USS MANASQUAN to determine the service range of the system. Observations and tests were also to be conducted on board a Navy blimp by Pierce. Military aircraft flights equipped with Loran to determine performance and range were scheduled.
Blimp K-2 Test
The first demonstration of the use of Loran was made using transmissions from the Fenwick, Delaware and the Montauk, New York experimental stations, Pierce made readings during the K-2 blimp test, on June 13, 1942. Pierce’s measurements were made on an improved model of the laboratory receiver indicator as the airship transited 250 miles between Lakehurst, New Jersey and Ocean City, Maryland and passed over lighthouses, bridges, and towers with accurate map locations. Loran charts were not available and readings were recorded as the various identifiable points were passed. Calculations the following week indicated errors of less than 20 yards, and the average of all errors was zero, to the nearest microsecond.
With the airship ready to return from Maryland, Pierce decided to home along a line of position from a distance of 50 to 75 miles offshore. With the Loran receiver turned off for an hour and the airship somewhere over the Atlantic Ocean, the receiver was turned on and set for the known reading at Lakehurst. Adjustments were made to the flight course in accordance with the Loran readings to head for the hangar. Upon landing, the blimp headed for the exact middle of the hangar.
USS MANASQUAN Test
Likewise, the month-long sea test June 17 to July 17, 1942 aboard USS MANASQUAN confirmed estimated values for sky wave performance at night and determined the range of service as 1400 nautical miles at night 700 for ground waves in the daytime. It was observed that in inclement weather not suitable for celestial navigation, that Loran provided the capability to maintain a useful line of position from one pair of stations.
On July 4, 1942 a B-24 equipped with a Loran laboratory receiver indicator made a test flight from Boston to Cape Sable, Nova Scotia. System performance data was obtained with signals from the Fenwick, Delaware and Montauk, New York transmitters.
On November 1, 1942, a PBY flight to Bermuda demonstrated the use of Loran in obtaining fixes. The results from these tests provided a basis for system expansion and its recommendation to navigational agencies.
The complete receiver design was completed and an order for 250 Loran receivers for ships was place with the Fada Radio & Electric Company. Philco was the builder of Loran receivers for aircraft. Loran transmitters with 100 KW, operating at 1950 KHz, provided ground-wave range of about 600 to 700 nautical miles over sea water and sky-wave range out to 1300 to 1400 nautical miles by night. Position errors were estimated at about one percent of the distance from the Loran transmitting station.
System Expansion Begins
The above mentioned June and July systems tests, notably the blimp test, resulted in immediate high level interest in the navigation system. The Navy, Army, and NDRC took steps to apply the system to the war effort. The Navy requested NDRC to immediately procure equipment and install Loran stations in Newfoundland, Labrador, and Greenland. Receivers were to be acquired for key United States and Canadian vessels.
Responsibility was given to the Army Signal Corps to procure airborne receivers for all services. Additional Northeastern Atlantic installations as well as the in the Aleutian region were planned. The Navy Bureau of Ships and the Coast Guard were assigned full responsibility covering all aspects of the system, including the training of operators and technicians for ground and shipboard equipment.
Following arrangements with the Canadian government, a slave station constructed at Baccaro, Nova Scotia operated with the double-pulsed master at Montauk Point and at a different pulse rate with a second master station constructed at Deming, Nova Scotia. By October I, 1942, the stations went into operation under the Royal Canadian Navy. These stations were the beginning of providing the Loran navigation system coverage across the Atlantic to the European Theater of war. Navigation assistance was essential for the wartime convoys. The two Canadian stations and Fenwick and Montauk provided operations 16 hours per day with the stations manned by US Coast Guard and Canadian Navy personnel standing watches supervised by NDRC engineers.
On January 1, 1943, authority over Loran was transferred from the NDRC MIT Radiation Laboratory to the Navy. On the same day, the Coast Guard assumed operation of the Montauk and Fenwick stations. At the same time, the Navy Hydrographic Office assumed responsibility for the computation, drafting, reproduction, and distribution of the Loran charts and tables. Radiation Laboratory prepared the early charts. For the Radiation Laboratory Loran team and the US Coast Guard, the North Atlantic, Aleutian, and Pacific Loran chains were in the future.