page_title: LORAN
section_title: LORAN
hierarchical_section_title: LORAN / History / LORAN
caption_attribution_description: English: AN/APN-4 LORAN in RCAF Canso aircraft. The associated electronics box is not seen in this photograph, and the position of the cabling suggests it is just out of frame off the bottom of the photo.
context_page_description: LORAN, short for long range navigation, was a hyperbolic radio navigation system developed in the United States during World War II. It was similar to the UK's Gee system but operated at lower frequencies in order to provide an improved range up to 1,500 miles with an accuracy of tens of miles. It was first used for ship convoys crossing the Atlantic Ocean, and then by long-range patrol aircraft, but found its main use on the ships and aircraft operating in the Pacific theater during World War II.
  LORAN, in its original form, was an expensive system to implement, requiring a cathode ray tube display. This limited use to the military and large commercial users. Automated receivers became available in the 1950s, but the same improved electronics also opened the possibility of new systems with higher accuracy. The U.S. Navy began development of Loran-B, which offered accuracy on the order of a few tens of feet, but ran into significant technical problems. The U.S. Air Force worked on a different concept, Cyclan, which the Navy took over as Loran-C, which offered longer range than LORAN and accuracy of hundreds of feet. The U.S.
context_section_description: The decision to switch to the long-range role meant that the high accuracy of the Gee system was not needed, which greatly reduced the need to address the timing problems. This change in purpose also demanded the use of even lower frequencies, which could reflect off the ionosphere at night and thus provide over-the-horizon operation. Two frequency bands were initially selected, 1.85 and 1.95 MHz for nighttime use (160 meters), and 7.5 MHz (40 meters). The 7.5 MHz, labeled "HF" on early receivers, was never used operationally.
  In mid-1942, Robert Dippy, the lead developer of the Gee system at the Telecommunications Research Establishment (TRE) in the UK, was sent to the US for eight months to help with LORAN development. At the time the project was being driven primarily by Captain Harding of the U.S. Navy, and they were concentrating entirely on a shipboard system. Dippy convinced them that an airborne version was definitely possible, leading to some interest by the U.S. Army Air Force. The Navy was unhappy about this turn of events. Dippy also instituted a number of simple changes that would prove extremely useful in practice. Among these, he outright demanded that the airborne LORAN receivers be built physically similar to the Gee receivers, so that they could be swapped out in service simply by replacing the receiver unit. This would prove extremely useful; RAF Transport Command aircraft could swap their receivers when moving to or from the Australian theatre. Dippy also designed the ground station timing equipment.
  It was around this time that the project was joined by both the U.S. Coast Guard and the Royal Canadian Navy. The project was still top secret at this time, and little actual information was shared, especially with the Coast Guard. The Canadian liaison was required, as ideal siting for the stations would require several stations in various locations in the Canadian Maritime Provinces. One site in Nova Scotia proved to be a battle; the site was owned by a fisherman whose domineering teetotaler wife was dead set against having anything to do with the sinful Navy men. When the site selection committee of J.A. Waldschmitt and Lt. Cdmr. Argyle were discussing the matter with the husband, a third visitor arrived and he offered the men cigarettes. They refused, and the hostess then asked if they drank. When they said they did not, the land was quickly secured.
  LORAN was soon ready for deployment, and the first chain went live in June 1942 at Montauk and Fenwick. This was joined shortly thereafter by two stations in Newfoundland, at Bonavista and Battle Harbour, and then by two stations in Nova Scotia, at Baccaro and Deming Island. Additional stations all along the U.S. and Canadian east coast were installed through October, and the system was declared operational in early 1943. By the end of that year additional stations had been installed in Greenland, Iceland, the Faroe Islands and the Hebrides, offering continuous coverage across the North Atlantic. RAF Coastal Command had another station installed in Shetland, offering coverage over Norway, a major staging ground for German U-boats and capital ships.
caption: AN/APN-4 LORAN in RCAF Canso (PBY) aircraft.
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