Radar Section of the 393rd

The following is a brief account of the 393rd Bomb Squadron (VH) Radar Section by Paul Metro, a former veteran of the Section.

     The 393rd Bomb Squadron was constituted 28 February 1944 and activated 11 March 1944 at Fairmont Army Airfield, Geneva, Nebraska as part of the 504th Bomb Group (VH).  The primary mission was to train combat crews for the B-29 Superfortress.

     On September 10, 1944 the 393rd was ordered to transfer to Wendover Army Airfield, Utah.  We arrived on September 14; in November the 504th went to Tinian short one bomb squadron.  The facilities at Wendover were not ready for B-29s, and there weren't any there yet, so Col. Tibbets gave us a ten day furlough beginning September 21.

     When we returned the ramp was fenced in and we had to wear special badges to be admitted.  More personnel were arriving daily, forming support units, to form the 509th Composite Group.  Col. Tibbets told us we were going to "hasten the war's end".  Our airplanes began arriving; we knew then that our mission was special, by the configuration of the planes (no gun turrets, etc.) and other circumstantial manifestations.

     We radar types had been subjected to loyalty investigations before we were eligible for radar training, so the signs, "What you see here, what you hear here, when you leave here, let it stay here!" wasn't anything new.  The Radar Section was comprised of 25 enlisted men and 2 officers, divided into 20 Radar (MOS 867) and 5 Radar Countermeasures (MOS 852) personnel.  We came from 18 states.

     Our primary function was to maintain the radar systems of the squadron's 15 B-29s.  This was done by performing pre-flight checks, replacing defective components and repairing any problems.  Radar is a coined word for RAdio Detection And Ranging using reflected micro-wave radio beams.  In the 1940's it was in its infancy, using vacuum tubes, soldered wire circuitry and coaxial cables.  It was very cumbersome, when compared to today's systems using printed circuits, transistors, etc.

     The major system was the AN/APQ13 used for search, bombing and navigation.  It was comprised of 19 units (total weight 433 lbs., excluding coaxial cables) located in various parts of the aircraft.  It was used on 30% of the "pumpkin" missions over Japan, but orders were, not to use radar for bomb release on the two atomic missions.  It was considered on the Nagasaki mission, but the bombardier didn't need it.

     Porter Richardson tells about the task of finding a clear range of frequencies to operate the atomic bomb controls.  Three radar receivers, covering the entire range of radar frequencies, were installed in a "Seek" aircraft.  After every "Seek" mission the RCM (Radar Countermeasures) guys would remove the receivers and check them out in the radar shack.  They figured that interest was in a narrow band of frequencies, so they removed the butterfly tuner disc from each receiver and black smoked them with a candle.  Their next check revealed that only a narrow band of one receiver was being used.  Thus, they made a discovery which they kept top secret, and reduced their workload by two-thirds.

     Other radar systems included the SCR718, radar altimeter; SCR695, IFF (Identification, Friend or Foe); SHORAN and LORAN, short and long range navigation systems and various RCM systems for detecting Japanese radar frequencies and diverting or jamming them.

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