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Robert Hobart Mayo (c1891-1957) of the Royal Aircraft Factory
1957 Obituary 
THE many people in aviation who knew Major R. H. Mayo, O.B.E., M.A., A.M.I.Inst.C.E., F.R.Ae.S., M.Inst.T., whether during his memorable work on the composite aircraft or in more recent years as a prominent official in sporting flying, will be grieved to learn of his death, in London on February 26, at the age of 66.
Educated at the Perse School and at Magdalene College, Cambridge, Robert Hobart Mayo very early showed exceptional abilities in mathematics and the mechanical sciences, and with an inclination towards aeronautics. At the early age of 24 he was appointed head of the experimental department at the Royal Aircraft Factory, but soon after the outbreak of war he sought action and served as an Royal Flying Corps pilot in France. Not for long was he permitted to keep his technical brilliance subdued: soon he was brought back to serve as senior commander of the Testing Squadron at Martlesham, and later as head of the Design (Aeroplane) Section, Air Ministry.
After the war he was a partner in a firm of consulting engineers, and in 1925 was appointed consulting engineer to Imperial Airways, becoming their technical general manager in 1936. It was during these inter-war years that he gained world-wide recognition as the designer of the Short-Mayo composite aircraft. Its bold principle was the mounting of a very highly loaded aircraft on top of another machine of comparatively light loading, and the release of the former in such a manner that the two components separated cleanly and rapidly in the vertical plane. The upper component was a Short float seaplane, powered with four Napier Rapier engines and named Mercury; the lower was a considerably modified Short Empire-type flying-boat, Maia, with four Bristol Pegasus engines. Normal cruising speed of Mercury was about 180 m.p.h., and a duration of over 21 hours could be achieved. The combination allowed the smaller aircraft to carry a payload of 1,000 lb over a range of 3,500 miles.
After a successful first separation on February 6, 1938, with Capt. J. Lankester Parker flying the lower component and Mr. H. L. Piper the upper, an Atlantic crossing was made in July of that year, Mercury reaching Montreal in 20 hr 20 min in the hands of Capt. (now A.V-M.) D. C. T. Bennett after separation from Maia (flown by Capt. A. S. Wilcockson) over Foynes. Subsequently Mercury made a number of other air-launched flights, on one of which, piloted by Bennett, it established a seaplane record—which still stands—from Scotland to South Africa. On another occasion over a ton of mail was taken non-stop to Alexandria on a routine Imperial Airways flight.
Maj. Mayo was appointed technical adviser to Imperial Airways shortly before the war. After 1945 he turned his attention mainly to the organizational side of aviation; the executive posts he held at various periods included the chairmanship of the Air League of the British Empire and of various R.Ae.C. committees, and a vice-presidency of the F.A.I. He was also a director of Airtech and Superflexit and acted as consultant and adviser to a number of firms.
1957 Obituary 
WE record with regret the death, on Tuesday last week, of Major Robert Hobart Mayo, O.B.E., M.A., F.R.Ae.S., aged 66.
After taking both mathematical and mechanical sciences tripos, Mayo entered the Royal Aircraft Factory before the 1914-18 war,during which he served with the Royal Flying Corps in France and at the Air Ministry.
He subsequently became a consulting engineer, and in 1935 formed a company to exploit the composite aircraft he patented. This overcame the problem of taking off an aircraft capable of carrying an economic load over long ranges by uniting with a less heavily loaded aircraft for the initial stages of the flight. An example was built for the ambitious task of carrying 1,000 lb of mail across the North Atlantic against head winds: cruising at 182 m.p.h., an endurance of 21.5 hours was needed.
The long range aircraft took the form of a float seaplane with four Napier "Rapier" H-16 air-cooled engines, and rode above a flying boat with four Bristol "Pegasus" engines that was essentially similar to the Short "Empire" liner. The two were named "Mercury" and "Maia" respectively.
The flight of "Mercury" to Montreal in July, 1938, was the first occasion on which a commercial load had been flown across the Atlantic.
Later that year a flight from Dundee to the Orange River established a seaplane distance record of 5997 miles which still stands.