 By late 1939, the Mk II was capable of delivering superior performance to the Mk IC, such as higher cruising and top speeds, increased all-up weight or alternatively greater range, and a raised ceiling.The Vickers Wellington was a twin-engined long-range medium bomber, initially powered by a pair of Bristol Pegasus radial engines, which drove a pair of de Havilland two-pitch propellers.Various different engines and propeller configurations were used on different variants of the aircraft, which included several models of both the Bristol Hercules and the iconic Rolls-Royce Merlin engines.