Short Mayo Composite
Encyclopedia
The Short Mayo Composite was a piggy-back long-range seaplane
/flying boat
combination produced by Short Brothers
to provide a reliable long-range air transport service to the United States
and the far reaches of the British Empire and the Commonwealth
.
s which were capable of operating long range routes across the British Empire
but could only attempt the trans-Atlantic route by replacing passenger and mail-carrying space with extra fuel.
It was known that aircraft could maintain flight with a greater load than is possible to take off with; Major Robert H. Mayo, Technical General Manager at Imperial Airways
(and later a designer at Shorts) proposed mounting a small, long-range seaplane on top of a larger carrier aircraft, using the combined power of both to bring the smaller aircraft to operational height, at which time the two aircraft would separate, the carrier aircraft returning to base while the other flew on to its destination. The British Air Ministry
issued Specification "13/33" to cover this project.
flying-boat, and the Short S.20 Mercury seaplane, the latter attached to a trestle-like pylon mounted on top of the fuselage of the former.
Although similar to the "C-Class" Empire boat, Maia differed in some considerable areas from that design: the sides were "tumblehome
" rather than straight up to give a greater beam for better stability on the water; larger control surfaces; an increase in total wing area from 1500 sq ft (139.4 m²) to 1750 sq ft (162.6 m²) ; the engines were mounted further from the wing root to provide clearance for Mercurys floats and the fuselage was swept up towards the tail to raise the tailplane relative to the wing. Like the Empire boats, Maia could be furnished to carry 18 passengers. Maia first flew (without Mercury) on 27 July 1937, piloted by Shorts' Chief Test Pilot
, John Lankester Parker
.
The upper component, Mercury, was a twin-float, four-engine seaplane crewed by a single pilot and a navigator, who sat in tandem in a fully enclosed cockpit. There was capacity for 1,000 lb (456 kg) of mail. Mercury's flight controls, except for elevator and rudder trim tabs, were locked in neutral until separation. Mercury's first flight, also piloted by Parker, was on 5 September 1937.
The mechanism that held the two aircraft together allowed for a small degree of movement. Lights indicated when the upper component was in fore-aft balance so trim could be adjusted prior to release. The pilots could then release their respective locks. At this point the two aircraft remained held together by a third lock which released automatically at 3,000 lb. The design was such that at separation Maia would tend to drop while Mercury would climb.
, on the west coast of Ireland, to Boucherville, Montreal, Canada, a flight of 2,930 miles (4,714.4 km). Maia, flown by Captain A.S. Wilcockson, took off from Southampton carrying Mercury piloted by Captain Don Bennett
. As well as Mercury, the launch aircraft Maia was also carrying 10 passengers and luggage. Mercury separated from her carrier at 8 pm to continue what was to become the first commercialThe British flying boats Caledonia and Cambria had made several non-stop survey flights of the Atlantic route already non-stop East-to-West transatlantic flight by a heavier-than-air machine. This initial journey took 20 hrs 21 min at an average ground speed of 144 mph (232 km/h).
The Maia-Mercury composite continued in use with Imperial Airways
, including Mercury flying to Alexandria, Egypt, in December 1938. After modifications to extend Mercurys range, it subsequently established a record flight for a seaplane of 6,045 miles (9,726.4 km) from Dundee
in Scotland to Alexander Bay
(in South Africa) between 6 and 8 October 1938.
Only one example of the Short-Mayo composite was built, the S.21 Maia with the registration G-ADHK and the S.20 Mercury (G-ADHJ). The development of a more powerful and longer-range Empire boat (the Short S.26
), the further development of in-flight refuelling and the outbreak of the Second World War combined to render the approach obsolete. Maia was destroyed in Poole Harbour
by German bombing on 11 May 1941. Mercury was flown to Felixstowe
for use by 320 (Netherlands) Squadron RAF
a Dutch seaplane reconnaissance unit serving with the Royal Air Force
at RAF Pembroke Dock. When this squadron was re-equipped with Lockheed Hudson
s, Mercury was returned to Shorts at Rochester on 9 August 1941 and broken up so that its aluminium
content could be recycled for use in the war effort.
Seaplane
A seaplane is a fixed-wing aircraft capable of taking off and landing on water. Seaplanes that can also take off and land on airfields are a subclass called amphibian aircraft...
/flying boat
Flying boat
A flying boat is a fixed-winged seaplane with a hull, allowing it to land on water. It differs from a float plane as it uses a purpose-designed fuselage which can float, granting the aircraft buoyancy. Flying boats may be stabilized by under-wing floats or by wing-like projections from the fuselage...
combination produced by Short Brothers
Short Brothers
Short Brothers plc is a British aerospace company, usually referred to simply as Shorts, that is now based in Belfast, Northern Ireland. Founded in 1908, Shorts was the first company in the world to make production aircraft and was a manufacturer of flying boats during the 1920s, 1930s, and 1940s...
to provide a reliable long-range air transport service to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and the far reaches of the British Empire and the Commonwealth
Commonwealth of Nations
The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...
.
Development
Short Brothers had built the Empire flying boatShort Empire
The Short Empire was a passenger and mail carrying flying boat, of the 1930s and 1940s, that flew between Britain and British colonies in Africa, Asia and Australia...
s which were capable of operating long range routes across the British Empire
British Empire
The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...
but could only attempt the trans-Atlantic route by replacing passenger and mail-carrying space with extra fuel.
It was known that aircraft could maintain flight with a greater load than is possible to take off with; Major Robert H. Mayo, Technical General Manager at Imperial Airways
Imperial Airways
Imperial Airways was the early British commercial long range air transport company, operating from 1924 to 1939 and serving parts of Europe but especially the Empire routes to South Africa, India and the Far East...
(and later a designer at Shorts) proposed mounting a small, long-range seaplane on top of a larger carrier aircraft, using the combined power of both to bring the smaller aircraft to operational height, at which time the two aircraft would separate, the carrier aircraft returning to base while the other flew on to its destination. The British Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...
issued Specification "13/33" to cover this project.
Design
The Short-Mayo composite project comprised the Short S.21 Maia, (G-ADHK) a design similar to the S.23 C classShort Empire
The Short Empire was a passenger and mail carrying flying boat, of the 1930s and 1940s, that flew between Britain and British colonies in Africa, Asia and Australia...
flying-boat, and the Short S.20 Mercury seaplane, the latter attached to a trestle-like pylon mounted on top of the fuselage of the former.
Although similar to the "C-Class" Empire boat, Maia differed in some considerable areas from that design: the sides were "tumblehome
Tumblehome
In ship designing, the tumblehome is the narrowing of a ship's hull with greater distance above the water-line. Expressed more technically, it is present when the beam at the uppermost deck is less than the maximum beam of the vessel....
" rather than straight up to give a greater beam for better stability on the water; larger control surfaces; an increase in total wing area from 1500 sq ft (139.4 m²) to 1750 sq ft (162.6 m²) ; the engines were mounted further from the wing root to provide clearance for Mercurys floats and the fuselage was swept up towards the tail to raise the tailplane relative to the wing. Like the Empire boats, Maia could be furnished to carry 18 passengers. Maia first flew (without Mercury) on 27 July 1937, piloted by Shorts' Chief Test Pilot
Test pilot
A test pilot is an aviator who flies new and modified aircraft in specific maneuvers, known as flight test techniques or FTTs, allowing the results to be measured and the design to be evaluated....
, John Lankester Parker
John Lankester Parker
John Lankester Parker OBE FRAeS Hon. MSLAE was Chief Test Pilot for Short Brothers from 1918 until his retirement in 1945. He joined Shorts in 1916 as a part-time test pilot and assistant to then Chief Test Pilot Ronald Kemp, having been recommended for the post by Captain, later Admiral Sir,...
.
The upper component, Mercury, was a twin-float, four-engine seaplane crewed by a single pilot and a navigator, who sat in tandem in a fully enclosed cockpit. There was capacity for 1,000 lb (456 kg) of mail. Mercury's flight controls, except for elevator and rudder trim tabs, were locked in neutral until separation. Mercury's first flight, also piloted by Parker, was on 5 September 1937.
"All eight engines were used during combined flight but the controls of Mercury were locked. The airfoil designs of the two aircraft were such that Mercury's wings were carrying the major part of the air load at the speed and height chosen for separation. Safety locks prevented separation until this speed and height were reached and both pilots had an unlocking handle, both of which had to be pulled to cause release."
The mechanism that held the two aircraft together allowed for a small degree of movement. Lights indicated when the upper component was in fore-aft balance so trim could be adjusted prior to release. The pilots could then release their respective locks. At this point the two aircraft remained held together by a third lock which released automatically at 3,000 lb. The design was such that at separation Maia would tend to drop while Mercury would climb.
Operations
The first successful in-flight separation was carried out from the Shorts works at Borstal, near Rochester, Medway, on 6 February 1938, Maia piloted by Parker and Mercury by Harold Piper. Following further successful tests, the first transatlantic flight was made on 21 July 1938 from FoynesFoynes
Foynes is a village and major port in County Limerick in the midwest of Ireland, located at the edge of hilly land on the southern bank of the Shannon Estuary. The population of the town was 606 as of the 2006 census.-Foynes's role in aviation:...
, on the west coast of Ireland, to Boucherville, Montreal, Canada, a flight of 2,930 miles (4,714.4 km). Maia, flown by Captain A.S. Wilcockson, took off from Southampton carrying Mercury piloted by Captain Don Bennett
Don Bennett
Air Vice Marshal Donald Clifford Tyndall Bennett CB CBE DSO RAF was an Australian aviation pioneer and bomber pilot who rose to be the youngest Air Vice-Marshal in the Royal Air Force. He led the "Pathfinder Force" from 1942 to the end of the Second World War in 1945...
. As well as Mercury, the launch aircraft Maia was also carrying 10 passengers and luggage. Mercury separated from her carrier at 8 pm to continue what was to become the first commercialThe British flying boats Caledonia and Cambria had made several non-stop survey flights of the Atlantic route already non-stop East-to-West transatlantic flight by a heavier-than-air machine. This initial journey took 20 hrs 21 min at an average ground speed of 144 mph (232 km/h).
The Maia-Mercury composite continued in use with Imperial Airways
Imperial Airways
Imperial Airways was the early British commercial long range air transport company, operating from 1924 to 1939 and serving parts of Europe but especially the Empire routes to South Africa, India and the Far East...
, including Mercury flying to Alexandria, Egypt, in December 1938. After modifications to extend Mercurys range, it subsequently established a record flight for a seaplane of 6,045 miles (9,726.4 km) from Dundee
Dundee
Dundee is the fourth-largest city in Scotland and the 39th most populous settlement in the United Kingdom. It lies within the eastern central Lowlands on the north bank of the Firth of Tay, which feeds into the North Sea...
in Scotland to Alexander Bay
Alexander Bay, Northern Cape
Alexander Bay is a town in the extreme north-west of South Africa, also known as the region of Little Namaqualand. It is located on the southern bank of the Orange River mouth. It was named for Sir James Alexander, who was the first person to map the area whilst on a Royal Geographical Society...
(in South Africa) between 6 and 8 October 1938.
Only one example of the Short-Mayo composite was built, the S.21 Maia with the registration G-ADHK and the S.20 Mercury (G-ADHJ). The development of a more powerful and longer-range Empire boat (the Short S.26
Short S.26
|-See also:-External link:* after conversion for RAF use...
), the further development of in-flight refuelling and the outbreak of the Second World War combined to render the approach obsolete. Maia was destroyed in Poole Harbour
Poole Harbour
Poole Harbour is a large natural harbour in Dorset, southern England, with the town of Poole on its shores. The harbour is a drowned valley formed at the end of the last ice age and is the estuary of several rivers, the largest being the Frome. The harbour has a long history of human settlement...
by German bombing on 11 May 1941. Mercury was flown to Felixstowe
Felixstowe
Felixstowe is a seaside town on the North Sea coast of Suffolk, England. The town gives its name to the nearby Port of Felixstowe, which is the largest container port in the United Kingdom and is owned by Hutchinson Ports UK...
for use by 320 (Netherlands) Squadron RAF
No. 320 Squadron RAF
No. 320 Squadron RAF was a unit of the Royal Air Force during World War II formed from the personnel of the Royal Netherlands Naval Air Service.-Formation:...
a Dutch seaplane reconnaissance unit serving with the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
at RAF Pembroke Dock. When this squadron was re-equipped with Lockheed Hudson
Lockheed Hudson
The Lockheed Hudson was an American-built light bomber and coastal reconnaissance aircraft built initially for the Royal Air Force shortly before the outbreak of the Second World War and primarily operated by the RAF thereafter...
s, Mercury was returned to Shorts at Rochester on 9 August 1941 and broken up so that its aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
content could be recycled for use in the war effort.
Specifications (S.20 Mercury)
Specifications (S.21 Maia)
In popular culture
- The children's novel The Sound of Propellors by Clive KingClive KingDavid Clive King is an English author best known for his children's book Stig of the Dump . He served in the Royal Navy Volunteer Reserve in the last years of World War II and then worked for the British Council in a wide range of overseas postings, from which he later drew inspiration for his...
follows the adventure of an Indian schoolboy who stows away on a fictional test flight from England to India, which is sabotaged by a German spy.
See also
External links
- 1935 article describing the proposed Short-Mayo Composite
- "Flying Boat Launches Sea Mail Plane in Air" Popular Mechanics, April 1935, article with drawing explaining concept of purposed Short Mayo Composition.
- Aero Stories
- Contemporary article in Time magazine, 14 February 1938
- Irish Inland Waterway News, Winter 2001
- Imperial Airways history
- Image of the Maia/Mercury at www.historyofaircargo.com
- Download link for "The Guild of Aircraft Pilots and Navigators of London 1929 - 2004"