De Havilland Mosquito B Mk IXThe B Mk IX was a high altitude development of the Mosquito B Mk IV. Development work on the original prototype Mosquito began in 1942, when it was fitted with Merlin 61 two stage supercharged engines and four bladed propellers. In this configuration it reached a height of 40,000 feet in June 1942, the highest then achieved by a Mosquito.
