Page 23 of the 1946 Argus report is more perplexing than any other. It shows front and back views of two ground components of a “VHF Omni-Directional Range” (VOR) navigation system. Sub-components are shown on several other pages of the report. VOR systems came into common use only in the 1950’s, and at that time were civilian systems, not military ones. So why was Argus working on a VOR system sometime before 1946?

Research [1] indicates that at least three prototype VOR systems were constructed during WWII. One was a civilian system whose components did not match those pictured in the Argus report. Two were military systems (both SCR-629) that were developed late in the war but never deployed after initial testing. Descriptions of both of these systems match the physical appearance of the components in the Argus report, but documentation at the National Archives says that they were prototyped by companies other than Argus.

1] The CAA Prototype: In 1938 the CAA (the Civil Aeronautical Administration, forerunner of the FAA) commissioned the creation of a prototype VOR system by a Washington, D. C. aviation radio consultancy called the Washington Institute of Technology. This prototype was delivered in 1944, but was not likely manufactured by the Washington Institute, which had very limited (if any) production capability. Examination of photographs of this system in the National Archives indicate that it was not at all like the system shown in the 1946 Argus report.

2] Army Air Force SCR-629 Prototype #1 [rotating antenna]: The Army Air Force’s Graphic Survey of Radio and Radar Equipment (dated May 1, 1945) describes a VOR system using a rotating antenna that corresponds quite well to the system shown in the 1946 Argus report. This system was mobile, designed to be contained in two large boxes installed in the back of a 4X4 truck. Records in the National Archives indicate that it was supplied by Federal Telephone and Radio Laboratories, a New Jersey company and a subsidiary of IT&T (which would have been unlikely to have employed Argus as a sub-contractor).

3] Army Air Force SCR-629 Prototype #2 [12-sector transmitter]: The Army Air Force evaluated a second VOR prototype at the same time. It was described as “a high frequency omni-directional radio range which transmits a radiation circle divided into 12 sectors, each sector being characterized by (the broadcast of) a distinctive code symbol.” Two examples were made, one by Federal Telephone (see above) and one by Air Associates Inc. of Teterboro, New Jersey.

Air Associates had about 50 employees, and characterized itself as “manufacturers and distributors of aviation materials and equipment.” The Air Associates VOR prototype was not evaluated by the AAF “because of its similarity in operation to the Federal model,” but it was delivered to the AAF at Wright Field in Ohio. Given the modest size of Air Associates, it is possible that Argus was contracted to construct the transmitter of the Air Associates VOR system.

So the identity of the Argus VHF Omni-directional Range system cannot be determined. It is likely to remain that way until an old HAM puts his storeroom of dusty WWII equipment up for sale on eBay.

[1] Our thanks to Jerry Woodhall of the Bendix Radio Foundation for his consultation on VOR navigation systems for this section, to Tom Culbert of Aviation Research Corporation for materials from the National Archives in College Park, Maryland, and to Kevin Conklin of the Phillipsburg, Pennsylvania Historical Foundation for tracking down old VOR systems in the Pennsylvania countryside in the hope of finding one from 1945.