09/30/2009. The first of a batch of 200 V-72 Vengeance II aircraft produced by Northrop, and destined for the RAF (s/n AF745 to AF944), this aircraft was retained in the USA. Converted to a test bed for the 3000 hp Pratt &Whitney XR-4360-1 Wasp Major radial engine, it was designated Vultee 85 XA-31A, allotted USAAF s/n 42-35824. Before flight testing it was redesignated Vultee 86 XA-31B. View also photo 11219.