VERLORT Radar
Photo - ???
The VERy LOng Range Tracking (VERLORT) radar was an extended-range version of the SCR-584 - often credited as "the radar that won WW II". The Verlort range was increased from 650 Km to 4000 Km and the dish diameter from 1.8 m to 3 m to give it a space-tracking capability. The Red Lake (Woomera) Mercury tracking station used the more accurate AN/FPS-16 radar installed at Woomera for previous space activities.
Photo - Alan Gilham
The Verlort radar performed reliably for the six Mercury orbital missions. It was then relocated to the new Gemini tracking station at Carnarvon as an acquisition aid and back-up for the even more accurate FPQ-6 radar to be installed there.
Although the Verlort was kept operational for the first few Carnarvon missions it was soon operationally delisted once the FPQ-6 proved its reliableility and other acquisition methods also proved sufficient.
Some technical descriptions
The SCR family of radars, developed at the MIT laboratories, was remarkable for the innovative MIT solutions to radar operations that are now met in modern radars by electronic methods.
The Verlort Plan Position Indicator (PPI) was driven by a mechanical computer once target acquisition occurred; the radar operator needed to keep a ‘hairline’ indicator manually centred on the target’s echo to maintain track.
Even more intriguing were the target acquisition techniques.
For targets where only crude position information was available, a helical scan was used to acquire the target. The dish was swung in a circle at 6 rpm along the expected path with the reflector tilted to and fro about 4° per dish revolution to create a helical spiral about 20° wide along the expected track path - see 'Helical scan mechanism' diagram on right.
Where there was more certainty about the target path, a nutating scan mode was used where the slightly offset dipole feed was rotated rapidly to produce off-axis radiation to increase the effective beam width from 2.5° to about 5.5° . The nutation was switched off when the target was acquired. See ‘conical scan beam’ diagram below left and ‘nutating antenna dipole feed’ below right.
Image – ‘Electronics’; Fig 1, Nov ’45, p.104
Image – ‘Electronics’; Fig 5, Dec ’45, p.107
For a detailed technical description of the SCR-584 radar published in the November & December 1945 issues of ‘Electronics’ magazine refer to http://www.hamhud.net/darts/scr584.html.
