Measures for Progress: A History of the National Bureau of Standards

398 WORLD WAR II RESEARCH (1941-45)
in the P—47 fighter plane in the European theater, saw service.9° They also
directed the bombs dropped on Hiroshima and Nagasaki.
The progressive reduction in size of the nonrotating radio fuze was
eagerly observed by Army Ordnance, since they wanted it for their trench
mortars. The fuzes in production, for all their miniaturization, still weren't
small enough when the request came to the Bureau in the late spring of 1944.
Besides the necessity of designing a fuze oniy one-third the size of those in the
bomb and rocket, while retaining all their functions, the fuze for the Army's
81-mm mortar shell had to be capable of withstanding a firing shock of
10,000 times the force of gravity or 10 times that of the rocket fuze.
The extreme requirements in size and ruggedness were largely met
by what was called a "radical innovation in electric construction" when the
subcontractor, Globe-Union, Inc., found a way to produce a considerable part
of the electric circuit of the fuze by painting conducting material onto ceramic
plates and Production of three models of mortar fuzes with these
new "so-called printed circuits" started a month after the surrender of Ger-
many. They were initially turned out at the rate of 100,000 a month. In
the expectation that the war in the Pacific would last until mid-1946 or early
1947, the rate had just been tripled when the war ended.9'
The pressure to complete development and hasten production of fuzes
both at the Bureau and in industry increased as preparations for the Nor-
mandy invasion began. Large quantities of bombs and rockets with the
proximity fuze were assembled for use in the preinvasion air assault to
soften up the beachhead. Teams headed by OSRD and Bureau members went
to England to indoctrinate the U.S. Air Force in the maintenance and use
of the fuzes. Then, shortly before D-day, the Air Force announced its deci-
sion not to use the fuze. In view of Allied air superiority, it was felt that
enemy recovery of one of the fuzes would make the weapon more advan-
tageous to them than to us. The proximity fuze for shells had been used
by fighter planes in the Pacific since early 1943, but their use had occurred
only over water where they were not recoverable. In Normandy, the fuze
°°Astin, ed., "Bomb, Rocket, and Torpedo Tossing," vol. 2, Summary Technical Report
of Division 4, NDRC (Washington, D.C., 1946) ; Astin, ed., "Photoelectric Fuzes and
Miscellaneous Projects," pp. 8—10.
'°' Although the metalizing art was believed well known, Globe-Union rightly considered
its printed circuit technique a trade secret, with great potentialities for the future, mak-
ing possible economic mass production, saving space and weight, and increasing the
reliability of electrical equipment. See Astin, ed., "Radio Proximity Fuzes for Fin-
stabilized Missiles," vol. 1, Summary Technical Report of Division 4, NDRC (Washington,
D.C., 1946), pp. 241—242, 248, 253—256; C. Brunetti and A. S. Khouri, "Printed electronic
circuits," Electronics, April 1946, p. 104.
Hinman, pp. 26—27; Baxter, p. 241; Rinehart MS, p. 182.