Silverplate

Silverplate was the code reference for the United States Army Air Forces participation in the Manhattan Project during World War II. more...

Originally the name for the aircraft modification project for the B-29 Superfortress to enable it to drop an atomic weapon, Silverplate eventually came to identify the training and operational aspects of the program as well. The airplane modification project fell under the purview of Project Alberta after March 1945. The original directive for the project had as its subject line "Silver Plated Project" but continued usage of the term shortened it to the one word "Silverplate".

Between February 1944 and December 1947 a total of 65 B-29s were modified to Silverplate specifications in five increments. Ultimately 53 of them served with the first nuclear weapons unit, the 509th Composite Group.

Initial phase

The project was initiated in October 1943 when Dr. Norman F. Ramsey, a member of the Los Alamos National Laboratory Group E-7, identified the B-29 Superfortress as the only airplane in the U.S. inventory capable of carrying either type of the proposed weapons shapes: the uranium 235 "gun-type fission weapon" shape and the plutonium implosion weapon shape. Furthermore, because the attachment box for the main wing spars was located between the bomb bays on the B-29, the gun-type weapon could only be a maximum of two feet in diameter.

USAAF sent instructions to its Army Air Forces Materiel Command at Wright Field, Ohio, on November 30, 1943, for a highly-classified B-29 modification project. The Manhattan Project would deliver full-sized mockups of the weapons shapes to Wright Field by mid-December, where AAFMC would modify an aircraft and deliver it for use in bomb flight testing at Muroc Army Air Field, California.

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