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Radar Indicator Lens, AN/APG-33 and-40 Radar for E-1 Fire Control System


Radar Indicator Lens, AN/APG-33 and-40 Radar for E-1 Fire Control System


While called a "Flight Indicator" on its label, this is essentially the radar scope lens for the AN/APG-33 and -40 Radar Systems of the E-1 Fire Control System developed by Hughes Aircraft for the US Air Force. These systems were put into use on the Northrup F-89 Scorpion and Lockheed F-94 Starfire Fighter/Interceptors in the 1950's.  See images of the scope on the F-94 and the F-89 (instrument panel from the F-89 flight manual). Made by Hughes Aircraft, part number 435-62-0001. This has also been observed on the Canadian Avro CF-100 Canuck (see cockpit image).

The E-1 fire control system used the APG-33 or -40 radar to continuously measure the range, azimuth and elevation of the identified target and allow the observer to take control if the “blip” was identified as unfriendly.

As found

"Produced by the Hughes Aircraft Company, the E-1 was the first in the E series of sophisticated fire-control systems that were to equip more modern planes. The Air Force ordered the system in June 1948, when it asked that the AN/APG-3 radar (being developed for the tail defense of the B-36) be adapted to the Northrop F-89. A November amendment of the June contract extended the requirement to the F-94. The modified AN/APG-3 radar was redesignated AN/ APG-33 and the entire system, including its A-1C gunsight, became the E-1 in late 1949. It was installed in early F-89s as well as F-94As and -Bs. Low-powered, the E-1 was fairly primitive alongside the E-5 of the rocket-firing F-94C. The system was nevertheless a pioneer achievement."

This twin-lens indicator was fitted to the radar scope projector, which would illuminate the image onto the first lens (furthest from view), which also contains a scale with numerals and markings printed upon the glass.  A ring rotates a second lens, which appears to be a polarizing lens to adjust the glare or brilliance of the radar image.

The artifact is in very good condition cosmetically, with the glass intact. It has a service label dated July 1958. Measures 3.25 inches diameter and ~4 inches long.

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