The Canadian Web Pages Of Jerry Proc has a great post on the History of LORAN.
BE reader Rod Pugh states: Loran was once top secret ! It played a valuable role defeating the Axis powers in WW2. Providing navigation for the next 50 years. Not a bad track record for 1940 technology!
LORAN SECURITY
Because the LORAN program was a secret during WWII, a security concept was applied whereby each station was designated with a letter so not to reveal the transmitter location in case any of the Loran charts/tables should fall into enemy hands.Loran stations also had Unit designators. The Unit number (i.e. Unit 10 for Nantucket) was used for issuing orders to personnel assigned to a station and all correspondence with the goal in mind of not revealing the transmitter location. It was decided early on in the program that the station and personnel were expendable and could not be protected.
There were other designators used post war. Dope 1/2/3 were code names for the stations in Greenland during the Cold War. This holds true for the stations that were established to support the Korean War (ELMO 1 – 7).
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This Loran-A chart shows the WWII era letter designations used by two US East coast stations. Station ‘C’ is Folly Beach and ‘H’ is Bodie Island. Click to enlarge. (Chart provided by Bill Dietz, Loran A History web site ) |
EARLY EQUIPMENTBecause of vacuum tube size and power requirements, LORAN only saw shipboard use initially because the equipment was too large for aircraft. By 1943 an airborne LORAN, the APN-4, was small enough to be used on large bombers and patrol aircraft. The APN-4 consisted of two units each about 1 ft. x 2 ft by 2.5 ft. One unit consisted of the power supply while the other contained the oscilloscope display tube, timing circuits and receiver. Together they weighed about 80 pounds. By 1945 the APN-9 came into use at an amazing weight reduction. It only weighed 40 pounds.
AN/APN-9 Loran ‘A’ set. Commercial fishermen also used these after WW2 until something better came on the market. (Image source unknown.) The oscilloscope screen was about four inches in diameter and would display a station master and associated slave signal from about 1500 miles over water and 600 miles over land. With practice a fix could be determined in about three minutes. As an example, the minimum error for navigating the 1400 miles to Japan from Tinian was about 28 miles. With two successive fixes ground speed, drift, and ETA could be determined. The relative simplicity of LORAN and the fact that it could be used regardless of weather made it invaluable an invaluable navigational tool until the aircraft arrived over Japan when airborne radar provided a more accurate fix. For some unknown reason the Japanese either never tried or failed to jam any of the LORAN systems.
For a comprehensive look on the placement of Loran chains during WWII, please select this link.
The complete LOARAN post is here.
(Ed. note: Thanks to BE reader Rod Pugh for the link.)
Great article about LORAN A. I used it with the USCG in 1960 and 1961 in the Western and South pacific. It was accurate enough that we established that several atolls were miles off the charted positions. (of course, some of these were charted by Captain Cook and later by the Japanese before WWII)
The following is a really great article about our very own LORAN station located in George, WA. It’s something I found through my local scanner boards (another geeky hobby of mine). While I agree that with GPS being so prevalent these days LORAN’s time may be at an end, the article does a great job of explaining the lengths the USCG has gone to in order to make sure LORAN has stayed on the air these many years, as well as some great technical desciptions of the station in George, WA.
http://www.locusinc.com/library/2004%20Nuts%20Bolts%202.pdf
Hey.
Nice post and some really interesting stuff about the Loran out here. Loved the old chart.
Put up link to this post in a post of mine about the Loran.
Thanks,
Velu