Historical Electronics Museum, Inc. - History of the Nation's Defense Electronics
Past Gallery

In 2003-2004 the National Electronics Museum featured a temporary exhibit on the AN/APQ-13 radar system. This system was flown on the B-29 Superfortress both during WWII and the Korea War and went on to be adapted for use as a ground based storm tracking radar. We owe Mr. Allen Weiner of Kennebunkport Maine a big thank you for the loan of the radar.

The story of the AN/APQ 13 radar begins with the British development of the H2S radar in 1942. RAF Bomber Command was committed to a strategy of night bombing but was having troubles successfully hitting its intended targets using conventional bombing tactics. Prewar experiments had shown that it was possible to identify ground targets by turning radar downward. Tests were conducted and it was found that the radar return of cities could be differentiated from those of open country. The British began developing 10 cm S-band radar called H2S. By the direction of the Prime Minister, Winston Churchill, the ten-centimeter radar was brought into immediate production. In January 1943, British Sterling and Halifax bombers were fitted with the H2S radars providing a ground mapping capability for navigation and primarily night bombing.

The H2X was a U.S. improvement on the H2S radar using a 3 cm X band radar. The shorter microwave length gave a sharper picture of the ground than the British equipment. B-24 bombers were converted to F-7 Pathfinder aircraft equipped with the H2X radars. Replacing the ball turret on the bottom of the aircraft these aircraft lead BTO or bomb through the overcast missions against Germany and targets in France in preparation for D-Day. These aircraft recorded 1132 sorties during WWII. Production H2X, made by Philco, were assigned the Army -Navy nomenclature AN/APS-15. Eventually this radar was placed on a several different aircraft assigned the Pathfinder role.

B-29's were equipped with improved H2X radar developed by Bell, Western Electric and M.I.T with the nomenclature AN/APQ-13, designating ground scanning radar. The USAAF adopted the British technique of night attacks making the use of radar essential. The radome was carried on the aircraft belly, between the bomb bays and was partially retractable. Unfortunately, the retracting motor gave quite a few problems and that lead to streamlining the radome shape and made it non-retractable. It operated at a frequency of 9375 45 megacycles and used a superheterodyne receiver. The radar was used for high altitude area bombing, search, and navigation. Computation from bombing could be performed by an impact predictor and Range Unit permitted a high degree of accuracy in locating beacons. AN/APQ-13 equipped B-29 aircraft were used through the beginning of the Korean conflict, 1950-1953.

In 1945 after a series of failures in an attempt to build a modern heavy bomber, the Soviet leadership decided to build a copy of the B-29, several of which had force landed in the USSR after raids on Japanese occupied China. The first copy, the TU-4 "Bull" flew in the spring of 1948. The AN/APQ-13 radar was also copied and was later named "Cobalt" by the NATO intelligence.

In late 1945 following the end of WWII, the AN/APQ-13 radar took on a new life when it was the first military radar converted to domestic peacetime application as Storm Warning radar. About thirty systems were converted and installed at military bases. It was the first of our weather radars. As interest in weather radar developed, the AN/APQ-13 radars were replaced by the AN/CPS-9 around 1949.

The history of the development, production and application of ground mapping radar continued on after the life of the AN/APQ-13 radar, but none have experienced the variation of aircraft, users, and applications experienced by the AN/APQ-13.

The National Electronics Museum is organized into thirteen related exhibit galleries:
1. Fundamentals Gallery
2. Communications Gallery
3. Early Radar Gallery
4. Cold War Radar Gallery
5. Modern Radar Gallery
6. Countermeasures Gallery
7. Under Seas Gallery
8. Electro-optical Gallery
9. Space Sensor Gallery
10. Past Gallery
11. Web Gallery
12. WWII Radar Kiosk
13. Cold War Radar Kiosk

Click here for an Adobe pdf showing the gallery layout

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