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Supermarine S.4

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The Supermarine S.4 was a 1920s British single-engined monoplane built by Supermarine. Designed by a team led by the company's chief designer, R. J. Mitchell, it was built to race in the 1925 Schneider Trophy contest.

S.4

The official photograph of the S.4, which appeared in Flight in October 1925

Role

Racing floatplane

National origin

United Kingdom

Manufacturer

Supermarine

Designer

R. J. Mitchell

First flight

24 August 1925

Status

Destroyed 23 October 1925

Number built

Mitchell's design was revolutionary. Aware of the need to reduce drag forces to increase speed, he produced a floatplane that was in marked contrast to the flying boats previously designed by Supermarine. Built of wood, and with an unbraced cantilever wing, it was powered by a Napier Lion engine developed to produce 700 horsepower (520 kW) over a short racing period. The S.4 was aerodynamic and aesthetically pleasing, but the cockpit position was potentially hazardous, as it restricted the pilot's view. Less than a month after its maiden flight on 24 August 1925, it raised the world's seaplane speed record to 226.752 miles per hour (364.922 km/h).

At Bay Shore Park in Baltimore in the US, the venue of the 1925 contest, the S.4's rear end was damaged by a falling pole during a gale prior to the event. During navigation trials on 23 October, the repaired aircraft was observed to be performing well, but then—for reasons that have not been fully explained—it went out of control, and was destroyed when it dived into the sea from 100 feet (30 m), injuring the pilot, Henri Biard.

Mitchell used the practical experience gained from his work on the S.4 when designing its immediate successor, the Supermarine S.5.

Design and development

During 1925, Supermarine's chief designer, R. J. Mitchell, was working on a new aircraft to compete in that year's Schneider Trophy race.[1] The decision to begin the design process was made jointly by Napier and Supermarine on 18 March 1925.[2] Following the success of the Americans during the previous contest, Mitchell was fully aware of the need to reduce drag forces to increase speed. Supermarine's new design was for a mid-wing, cantilever floatplane. It was comparable to a French monoplane, the Bernard SIMB V.2, which had broken the flight airspeed record in December 1924.[3][4] The new design was in marked contrast to the flying boats Mitchell had designed for previous Schneider Trophy races, which had won in 1922 and come third behind the American Curtiss CR seaplanes in 1923.[5]

The name S.4 was designated by Mitchell, "S" standing for Schneider.[3] He saw the three previous Schneider Trophy entrants (the Supermarine Sea Lion series) as S.1, S.2, and S.3;[2] the S.4 was the first Schneider Trophy entrant to be supported by the British government, who agreed to buy the aircraft if Supermarine and Napier covered the initial costs of development and construction.[6] The Air Ministry provided the British teams with greater freedom than was given by the US government to their designers.[3]

The S.4 was a monoplane seaplane with an unbraced cantilever wing and semi-monocoque fuselage, powered by a specially developed version of the Napier Lion,[7] a water-cooled engine developed to produce 700 horsepower (520 kW) over a short racing period.[8] The aircraft was primarily constructed from wood: the single-piece unbraced wing had two spars with spruce flanges and plywood webs, and was covered with plywood braced by stringers.[7] The fuselage had a covering of diagonally laid spruce planking over plywood formers constructed around a pair of steel A-frames,[7] to which the engine bearers and wing spars were attached and which carried the floats.[9] The single-step floats were metal.[10] The S.4 lacked the newly designed surface radiators, at that time still unavailable, but it was aerodynamic and aesthetically pleasing.[3] The radiators, which were mounted under the wings, were the only part of the machine to extend from the fuselage.[2]

In September 1925, Flight reported:[11]

Perhaps one may describe the Supermarine-Napier S.4 as having the appearance of having been designed in an inspired moment, but having all that is considered best in British construction incorporated in its details. That the design is bold, no one will deny, and we think the greatest credit is due to Mr. R. J. Mitchell, chief designer of the Supermarine Aviation Works, for his courage in breaking away from stereotyped methods and striking out on entirely novel lines.

— "The Schneider Cup Seaplane Race", Flight (25 September 1925)

Operational history

Henri Biard and R. J. Mitchell in front of the S.4

Allocated the civil registration G-EBLP and the Air Ministry serial number N197,[12][13] the S.4 first flew on 24 August 1925, witnessed by Mitchell, who went out in a motorboat with Lord Mountbatten.[2][14] Testing took place at Calshot, because of the long take-off runs that were required.[3]

Supermarine's chief test pilot Henri Biard was reportedly unhappy with the S.4, disliking the unbraced wings and the cockpit position, which was well back behind the wings. The location of the cockpit was potentially hazardous, as it restricted the pilot's view ahead, particularly during take-off and landing. On its maiden flight, the S.4 came close to colliding with an ocean liner because of this.[15][note 1]

On 13 September 1925, on a 1.864-mile (3.0 km) straight course over Southampton Water,[14] the S.4 raised the world's seaplane speed record (and the British speed record) to 226.752 miles per hour (364.922 km/h),[15][12] which created a sensation in the press when it was announced a month later.[3][15]

Schneider Trophy competition of 1925

The Supermarine S.4 (left of centre) prior to the start of the 1925 Schneider Trophy competition

With high hopes of a British victory in the forthcoming Schneider Trophy competition at Bay Shore Park, Baltimore, the S.4, together with two Gloster III biplanes, was shipped to the US aboard the SS Minnewaska, free of charge.[16][17] During the voyage, Supermarine's pilot Biard slipped playing tennis, and injured his wrist.[17]

Bad weather meant that those Schneider Trophy competitors that had already arrived for the competition had little opportunity to practise the course.[18] The aircraft were forced to remain in their crates while canvas hangars were being erected on the beach to accommodate them.[17] Biard caught influenza, but recovered sufficiently to participate in the competition. The windy conditions had, however, blown down the hangar where the S.4 was being kept, and the rear end of the aircraft had been damaged by a falling pole. The S.4 was repaired in time to take part in navigation trials on 23 October 1925.[18]

During the trials, the S.4 initially performed well but, upon its return to shore, the control column began to oscillate violently and Biard lost control of the machine at high speed.[18] The S.4 was seen to stall, before falling flat into the sea from 100 feet (30 m). Biard, who initially had lost consciousness when he was still strapped into the aeroplane, was able to resurface from the sea bed, and cling to some floating wreckage.[19][20] The first launch sent out to him broke down with engine trouble, and he had to be rescued by a second launch. Mitchell, who was on board the boat that rescued Biard, jokingly asked the injured man: "Is the water warm?"[21] Biard was later found to have broken two ribs.[19]

Parts of the wrecked aircraft were salvaged.[20][22] Most sources have suggested the accident was due to flutter,[23] but although an enquiry was later held,[20] the reasons for the crash were never clearly established.[24]

Aftermath of the crash

The race was won two days later by Lieutenant James Doolittle, flying a Curtiss R3C at an average speed of 232.573 mph (374.443 km/h), which was faster than the S.4's world record of a month before.[23] It was evident to the other national teams that the American approach towards the contest—which involved training for the pilots and development testing of the aircraft—was required. Mitchell was to say as much when he gave a lecture to the Royal Aeronautical Society in 1927. From 1925 onwards, the Air Ministry developed a policy of using wind tunnel tests to analyse the performance of the high-speed aircraft they produced.[19]

Legacy

Screencapture from the British film The First of the Few (1942), which included footage of the Supermarine S.4 taking off

The Supermarine S.4 was a revolutionary aircraft that was years ahead of its time, and which "set the pattern in specific aircraft design that persisted through the [1930s and 1940s]".[25] It was designed with new technology, with floats that were the most advanced of their time, and a wing, with its lack of external bracing wires, that had never before been incorporated into a Supermarine aircraft. The aviation historian John D. Anderson notes that the aircraft "represented Mitchell's willingness to incorporate new technology within the framework of a tried and tested intellectual methodology for conceptual design", and was "a revolution in airplane design" that "influenced all subsequent Schneider racers".[26] The winning aircraft of the 1926 Schneider contest, the Italian Macchi M.39, was distinctly similar to the S.4.[27] Mitchell used the practical experience gained when he designed its successor, the Supermarine S.5.[28] The S.4 has been described as "his first outstanding success".[29]

Drawings and archival footage of the plane's construction, and five minutes of film that show the aircraft's first takeoff and flight, are preserved in Leslie Howard's biographical film about Mitchell, The First of the Few (1942).[30]

The S.5's design included features intended to reduce the wing flutter considered at the time to have contributed to the loss of the S.4; the monoplane wings were braced with wires.[31] The S.5 was given a smaller fuselage cross section and more streamlined floats, modifications designed to produce increases in speed over its predecessor. The greatest speed increase—considered to be approximately 24 miles per hour (39 km/h)—was produced by the introduction of surface radiators to cool the engine, as they significantly reduced the drag forces acting on the aircraft.[27] Tests made on a model of the S.4 at the National Physics Laboratory which were done after the crash revealed that the Lamblin radiators accounted for a third of the aircraft's drag and that without them the S.4 would have been the "cleanest" monoplane in the world.[32]

Specifications

Data from Supermarine Aircraft since 1914[33]

General characteristics

Crew: 1

Length: 26 ft 7+3⁄4 in (8.122 m)

Wingspan: 30 ft 7.5 in (9.335 m)

Height: 11 ft 8.75 in (3.5751 m)

Wing area: 139 sq ft (12.9 m2)

Empty weight: 2,600 lb (1,179 kg)

Gross weight: 3,191 lb (1,447 kg)

Powerplant: 1 × Napier Lion VII W-12 liquid-cooled piston engine, 680 hp (510 kW) at 2,000 rpm

Propellers: 2-bladed fixed-pitch propeller

Performance

Maximum speed: 239 mph (385 km/h, 208 kn) [12]

Wing loading: 23 lb/sq ft (110 kg/m2)

Power/mass: 0.21 hp/lb (0.35 kW/kg)

Notes

The liner involved was White Star Line's Majestic, which was at the time at the entrance to Southampton Water.[14]

References

Eves & Coombs 2001, p. 96.

Andrews & Morgan 1981, p. 175.

Eves & Coombs 2001, p. 115.

"The World's Speed Record". Flight. 18 December 1924. p. 796. ISSN 0015-3710.

Green, William (July 1967). "Supermarine's Schneider Seaplanes". Flying Review International. Vol. 10, no. 11. p. 744.

James 1981, pp. 197–198.

James 1981, p. 198.

Andrews & Morgan 1981, p. 177.

Andrews & Morgan 1981, pp. 175–178.

James 1981, p. 200.

"The Schneider Cup Seaplane Race". Flight. Vol. 17, no. 874. 24 September 1925. p. 613. ISSN 0015-3710.

Jackson 1973, p. 317.

Lewis 1970, p. 144.

Mitchell 2002, p. 66.

Andrews & Morgan 1981, p. 178.

"The Schneider Cup Seaplane Race: British Representatives Leave on Saturday". Flight. Vol. 17, no. 874. 24 September 1925. pp. 609–614. ISSN 0015-3710.

Eves & Coombs 2001, p. 117.

Andrews & Morgan 1981, p. 179.

Andrews & Morgan 1981, p. 180.

Mitchell 2002, p. 68.

Eves & Coombs 2001, p. 119.

"The 1925 Schneider Trophy Race: Flight Correspondent's Special Account". Flight. Vol. 17, no. 881. 12 November 1925. pp. 747–752. ISSN 0015-3710.

"The 1925 Schneider Trophy Race". Flight. Vol. 17, no. 879. 29 October 1925. p. 703. ISSN 0015-3710.

Glancey 2008, p. 27.

Andrews & Morgan 1981, pp. 6, 175.

Anderson 2018, pp. 126–128.

Andrews & Morgan 1981, p. 182.

Ritchie 2004.

"Papers of RJ Mitchell" (Catalogue description). The National Archives. Retrieved 15 September 2022.

Aldgate & Richards 1994, p. 53.

Loftin 1985, p. 75.

Eves & Coombs 2001, p. 167.

Andrews & Morgan 1981, p. 203.

Sources

Aldgate, Anthony & Richards, Jeffrey (1994). Britain Can Take it: British Cinema in the Second World War (2nd ed.). Edinburgh: Edinburgh University Press. ISBN 978-0-7486-0508-8.

Anderson, John D. (2018). "Design for Speed: R. J. Mitchell and the Spitfire". The Grand Designers: The Evolution of the Airplane in the 20th Century. Cambridge Centennial of Flight. Cambridge: Cambridge University Press. pp. 116–155. doi:10.1017/9780511977565.006. ISBN 978-11083-4-056-4.

Andrews, C. F. & Morgan, Eric B. (1981). Supermarine Aircraft since 1914. London: Putnam. ISBN 978-03701-0-018-0.

Eves, Edward & Coombs, L. F. E (2001). The Schneider Trophy Story. St. Paul, Minnesota: MBI. ISBN 978-07603-1-118-9.

Glancey, Jonathan (2008). Spitfire: The Illustrated Biography. London: Atlantic Books. ISBN 978-18435-4-799-0.

Jackson, A. J. (1973). British Civil Aircraft, 1919–1972. Vol. 3. London: Putnam. ISBN 978-0-85177-818-1.

James, Derek N. (1981). Schneider Trophy Aircraft 1913–1931. London: Putnam. ISBN 978-0-370-30328-4.

Lewis, Peter (1970). British Racing and Record-Breaking Aircraft. London: Putnam. ISBN 978-0-370-00067-1.

Loftin, Laurence K. (1985). Quest for Performance: The Evolution of Modern Aircraft. Washington, DC: Scientific and Technical Information Branch, National Aeronautics and Space Administration. ISBN 978-01600-2-221-0.

Mitchell, Gordon (2002). R.J. Mitchell: Schooldays to Spitfire. London: Tempus Publishing. ISBN 978-0-7524-3727-9.

Ritchie, Sebastian (2004). "Mitchell, Reginald Joseph". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/35046. OCLC 56568095. Retrieved 15 December 2020. (Subscription or UK public library membership required.) (subscription may be required or content may be available in libraries that are in the UK)

External links

Wikimedia Commons has media related to Supermarine S.4.

Will England Win it? and Britain's Fine Bid for Schneider Cup (film footage of the S.4 at Calshot, from British Pathé)

Schneider Trophy Races, a history from Bluebird

Last edited 3 hours ago by HeyElliott

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