Boeing XB-15

The Boeing XB-15, company Model 294, was an American bomber designed in 1934 as a test for the United States Army Air Corps to find out whether a heavy bomber with a range of 5,000 miles could be built. For a year from mid 1935 it was designated the XBLR-1. When it first flew in 1937 it was the largest and most voluminous airplane ever built in the United States, and it set load-to-altitude records for land-based aircraft. Its wings were big enough for flight engineers to enter through a crawlway and make repairs in flight. The only example was retired in December 1944 and ordered scrapped in Panama in June 1945.