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Bombing Navigation Computer Indicator ID-165/APA-44, of APQ-34 System


Bombing Navigation Computer Indicator ID-165/APA-44, of APQ-34 System


This is a rare example of the post WWII ID-165 indicator for the APA-44 electronic analog computer used in the APQ-24 bombing-navigation system used in the US Air Force B-29 Superfortress.

According to the USAF's Development of Airborne Armament 1910 - 1961, Volume I Bombing Systems: 

The development of the Western Electric Company APA-44 electronic analogue computer, however, was the key factor in Air Force attempts to equip modern bombers with a truly integrated bombing-navigation system. The APA-44 was under development in 1945 and ultimately became a prime component of three bombing-navigation systems. An early model was delivered to Dayton late in 1945 and then subjected to an extensive flight test program primarily at Boca Raton, Florida.

Three APA-44's had been built and delivered to the Air Force by the end of August 1946. The first model had already undergone eight months of flight testing before being returned to Bell Telephone Laboratories to be completely rebuilt. Together with a modified APQ-7 radar (designated the APS-24), it was installed in a B-29 aircraft in November to form the AN/APQ-16 radar bombing system. The third APA-44 model was installed in a B-17 and employed with a new Western Electric search radar, the APS-22, to form the AN/APQ-34 bombing-navigation system. The second model of the computer remained at the contractor's facility for design flight tests,20 completed in February 1947. At this juncture, the APQ-34 at Boca Raton was just beginning flight testing in a B-17, but engine trouble had thus far prevented B-29 flights with the APQ-16. February 1947 also marked the appearance of the development model of a new Western Electric search radar that was to make the other systems obsolete before they ever became operational.

This was the APS-23, a high resolution, high altitude radar using the best features of the APS-22 and incorporating the common 360-degree scan, provisions for "sector scan" (in which the antenna oscillated through any desired portion of a circle), and a "displaced center" scan with vertex of the sweep starting at or even below the bottom of the cathode ray tube. The company had been working on the APS-23 since mid-1945 and also intended to use this radar in a combined optical and electronic bombing system to be operated by one man.

The APS-23, when combined with the APA-44 computer, formed the APQ-24 bombing-navigation system, a fully synchronous radar system without provision for an optical bombsight tie-in. The AN/APQ-24 mock-up inspection took place at Boca Eaton in May 1947, and after the contractor complied with recommended modifications, system installation in a B-29 began early in June.

This indicator either appeared on the panel of the pilot, navigator, or bombardier, or perhaps 2 or all of these positions. We speculate that the Time to Go indicator is the time to the bombing target, or IP, and the Degrees Steering indicates the direction toward the target from the current course of the aircraft. 

The indicator is in very good condition given its age. Measures 3.5 inches diameter by ~ 2 inches deep.

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