The mystery aircraft in our last issue was the Boeing XB-15. Built as a bomber, it became a transport, renamed the XC-105.
This behemoth resulted from a 1934 Army Air Corps proposal for a bomber capable of flying 5,000 miles. It was briefly known as the XBLR-1 but became the XB-15 before its first flight October 15, 1937--two years after the maiden flight of the same planemaker's smaller but less trouble-prone B-17 Flying Fortress. Even when it first took to the air, experts realized the XB-15 offered no advantage over existing bombers. They saw this big ship as a research vehicle, to enhance aeronautical knowledge.
For its size, the XB-15 was somewhat underpowered with four Pratt & Whitney R-1830-11 radi al engines delivering 850 horsepower apiece. Its broad wing, with a 149-foot span, was so big a flight engineer could enter via a crawlway to make minor repairs while in flight.
Assigned to the 2nd Bombardment Group at Langley Field, Virginia, the XB-15 in the hands of Major Caleb V Haynes flew a humanitarian mission to Chile in following a 1939 earthquake there.
The XB-15 undertook tests hauling heavy cargoes in Fairfield, Ohio, and in 1940 went to Panama for classified testing of...