10/31/2011. Remarks by Ray Watkins: "In 1933 the last production Wapiti Mk.I (s/n J9102) was assigned to Westland and the Bristol Aeroplane Company for use as a flying testbed for the Bristol Phoenix I air-cooled diesel engine. The success of early trials led to the aircraft appearing at the RAF Display at Hendon in June 1933.

Results with bench tests of a supercharged version, the 485 hp Phoenix II, and subsequent flight testing, led to an attempt on the world altitude record on May 11, 1934. The aircraft, piloted by Harald Penrose, reached a height of 27,453 ft (8,373 m), which remains the altitude record for a diesel-powered aircraft. The photo shows the aircraft fitted with the Phoenix II engine for the record attempt."