Silverplate was the code reference for the United States Army Air Forces participation in the Manhattan Project during World War II. 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.
Read more about Silverplate: Initial Phase, Testing of Bomb Shapes, Wartime Production Versions, Silverplate Operational Units, Follow-up Program