In 1938 Consolidated ventured to build an efficient large flying boat with a high aspect ratio Davis wing and two big R-3350 Cyclone engines. The Model 31 prototype, NX21731, first flew on 5 May 1939, but no commercial orders were forthcoming. NX21731 was then modified as the XP4Y-1 patrol bomber and the P4Y was ordered into production by the US Navy, but this was cancelled as all R-3350 engines were needed for the B-29. NX21731 allocated BuNo 27852. Photo from: Consolidated / Detroit Public Library