Here are the reports about the single B-29 converted and used for tests with Tallboy between March and June 1945.
The recommendation was that a single Group (which would be 45 aircraft) should be equipped to carry Tallboy. But further work was required on the conversion to iron out problems and to make the same aircraft compatible with Grand Slam. Another aircraft had also been modified to take both bombs and was under test by the end of June 1945. And note that the operational combat radius with Tallboy a projected 1,500 miles, which wasnt too far short of an unmodified B-29 (1,600-1,800 miles). I wonder what effect carrying the Grand Slam would have?
Personal view, it would be difficult to get the aircraft conversion finalised, built, a Group selected, equipped, trained and deployed before Operation Coronet, the invasion of Honshu Japan, planned for March 1946.
In March 1946 the USAAF did deploy 3 B-29 test aircraft as part of Project Ruby to drop bombs on concrete bunkers at Farge and on Heligoland. To the RAF this was known as Operation Front Line and 15 squadron took part. Later US tests came under the title Ruby II or Harker Project.
Project Ruby came about towards the end of World War II due to the failure of the large bombs developed to penetrate the reinforced concrete shielded targets in Germany. Both the Army Air Force and
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The very first elements of the RAF Tiger Force, the Airfield Construction Service squadrons necessary to build the airfields for them, arrived at Eniwetok in the Marshall Is, under the designation "Shield Force", on 16 Aug 1945 where they sat for 4 days until new plans could be made for them. Then it was off to Manus and then Hong Kong where they arrived on 4 Sept and were put to use repairing facilities in the Colony.
