Convair Model 37

The Convair Model 37 was a very large six-engine piston airliner that the American manufacturer Convair planned but never built. It was the civil passenger version of the XC-99, the single prototype military cargo transport that Convair derived from the B-36 bomber, an aircraft able to carry 400 armed soldiers across the Atlantic. Pan American World Airways placed an order for 15 of the type for its Atlantic routes, and the fuselage was to have two decks with a target range of 4,200 miles (6,800 km). The project ended on paper because the Pratt and Whitney Wasp Major engines of the XC-99 burned too much fuel to run an airliner economically, no more powerful turboprop was yet ready as a replacement, and an order of 15 aircraft did not justify going ahead.