AGrumman G-111 Albatross amphibious flying boat landingOS2U Kingfisher in 1944. Seaplanes were commonly used in World War II for reconnaissance and search and rescue. They were launched from ships or seaplane tenders, or could take off from water in the right conditions.
Aseaplane is a poweredfixed-wing aircraft capable oftaking off andlanding (alighting) on water.[1] Seaplanes are usually divided into two categories based on their technological characteristics:floatplanes andflying boats; the latter are generally far larger and can carry far more. Seaplanes that can also take off and land on airfields are in a subclass calledamphibious aircraft, or amphibians. Seaplanes were sometimes calledhydroplanes,[2] but currently this term applies instead tomotor-powered watercraft that use the technique ofhydrodynamic lift to skim the surface of water when running at speed.[1]
The use of seaplanes gradually tapered off after World War II, partially because of the investments in airports during the war but mainly because landplanes were less constrained by weather conditions that could result in sea states being too high to operate seaplanes while landplanes could continue to operate. In the 21st century, seaplanes maintain a few niche uses, such as foraerial firefighting, air transport around archipelagos, and access to undeveloped or roadless areas, some of which have numerous lakes. In British English, seaplane is sometimes used specifically to refer to a floatplane, rather than a flying boat.
The word "seaplane" is used to describe two types of air/water vehicles: the floatplane and theflying boat.
The term "seaplane" is used by some to mean "floatplane". This is the standard British usage.[1][3] This article treats both flying boats[4] and floatplanes[5] as types of seaplane,[6] in the US fashion.
Anamphibious aircraft can take off and land both on conventionalrunways and water. A true seaplane can only take off and land on water. There are amphibious flying boats and amphibious floatplanes, as well as some hybrid designs,e.g., floatplanes with retractable floats.
Modern (2019) production seaplanes range in size from flying-boat typelight-sport aircraft amphibians, such as theIcon A5 andAirMax SeaMax, to the 100,000 lbShinMaywa US-2 andBeriev Be-200 multi-role amphibians. Examples in between include theDornier Seastar flying-boat type, 12-seat, utility amphibian and theCanadair CL-415 amphibious water-bomber. The Viking Air DHC-6 Twin Otter andCessna Caravan utility aircraft have landing gear options which include amphibious floats.
Afloatplane has slender floats, mounted under thefuselage.[7] Two floats are common, but other configurations are possible. Only the floats of a floatplane normally come into contact with water. The fuselage remains above water. Some small land aircraft can be modified to become float planes, and in general, floatplanes are small aircraft. Floatplanes are limited by their inability to handle wave heights typically greater than 12 inches (0.31 m). The floats add to the empty weight of the airplane and to thedrag coefficient, resulting in reduced payload capacity, slower rate of climb, and slower cruise speed. British usage is to call floatplanes "seaplanes" rather than use the term "seaplane" to refer to both floatplanes and flying boats.[8]
Floatplanes have often been derived from land-based aircraft, with fixed floats mounted under the fuselage instead of anundercarriage (featuring wheels).Floatplanes offer several advantages since thefuselage is not in contact with water, which simplifies production by not having to incorporate the compromises necessary for water tightness, general impact strength and the hydroplaning characteristics needed for the aircraft to leave the water. Attaching floats to a landplane also allows for much larger production volumes to pay for the development and production of the small number of aircraft operated from the water. Additionally, on all but the largest seaplanes, floatplane wings usually offer more clearance over obstacles, such as docks, reducing the difficulty in loading while on the water. A typical single engine flying boat is unable to bring the hull alongside a dock for loading while most floatplanes are able to do so.
Floats inevitably impose extradrag and weight, rendering floatplanes slower and less manoeuvrable during flight, with a slower rate of climb, than aircraft equipped with wheeled landing gear. Nevertheless,air races devoted to floatplanes attracted much attention during the 1920s and 1930s, most notably in the form of theSchneider Trophy, not least because water takeoffs permitted longer takeoff runs which allowed greater optimization for high speed compared to contemporary airfields.
There are two basic configurations for the floats on floatplanes:
"single float" designs, in which a single large float is mounted directly underneath the fuselage, with smaller stabilizing floats underneath the wingtips, on planes like theNakajima A6M2-N
"twin float" designs, with two main floats mounted side by side outboard of the fuselage. Some early twin float designs had additional wingtip stabilizing floats.
The main advantage of the single float design is its capability forlandings in rough water: a long central float is directly attached to the fuselage, this being the strongest part of the aircraft structure, while the smaller floats under the outer wings provide the aircraft with lateral stability. By comparison, dual floats restrict handling, often towaves as little as one foot (0.3 metres) in height.[9] However, twin float designs facilitatemooring andboarding, and – in the case oftorpedo bombers – leave the belly free to carry atorpedo.
Aflying boat is a type of seaplane with ahull, allowing it to land on water.[10] It differs from afloatplane in having afuselage that is purpose-designed for flotation, while floatplanes rely on fuselage-mounted floats forbuoyancy.[citation needed] Though a flying boat’s fuselage provides buoyancy, it may also utilize under-wingfloats or wing-like hull projections (calledsponsons) for additional stability.[citation needed]
Ascending into common use during theFirst World War, flying boats rapidly grew in both scale and capability throughout theinterwar period, during which time numerous operators found commercial success with the type. Flying boats were some of the largest aircraft of the first half of the 20th century, exceeded in size only bybombers developed during theSecond World War. Their advantage lay in using water instead of expensive land-based runways, making them the basis for internationalairlines in the interwar period. They were also commonly used asmaritime patrol aircraft andair-sea rescue, particularly during times of conflict. Flying boats, such as thePBY Catalina andShort Sunderland, played key roles in both theAtlantic andPacific Theater of the Second World War.[citation needed][11]
The popularity of flying boats gradually tailed off during theCold War era, partially because of the difficulty in maintaining operations in inclement weather, when sea conditions may easily prevent takeoffs and landings while land-based aircraft are unaffected, in addition to investments in airports during the conflict that eased the introduction of land-based airliners that were larger and more efficient. Despite being broadly overshadowed, limited use of flying boats continued with some operators, such as in the cases of theShin Meiwa US-1A andMartin JRM Mars. In the 21st century, flying boats maintain a few niche uses, such asdropping water on forest fires, air transport aroundarchipelagos, and access to undeveloped areas. Many modern seaplane variants, whether float or flying boat types, are convertible amphibious aircraft, where either landing gear or flotation modes may be used to land and take off.[citation needed]
Dornier X, a flying boat airliner of the interwar period
Taking off on water was attempted by some early flight attempts, but water take off and landing began in earnest in the 1910s and seaplanes pioneered transatlantic routes, and were used in World War I. They continued to develop before World War II, and had widespread use. After World War II, the creation of so many land airstrips meant water landings began to drift into special applications. They continued in niches such as access in remote areas, forest fire fighting, and maritime patrol.
The quest for an aircraft that could take off or land from water began with float planes, which are not flying boats.[citation needed]
In 1876, FrenchmanAlphonse Pénaud filed the first patent for a flying machine with a boat hull and retractable landing gear, but failed to build one. AustrianWilhelm Kress is credited by some with attempting to build the first successful seaplaneDrachenflieger, afloatplane, in 1898, although its two 30 hpDaimler engines were inadequate for take-off, and it later sank when one of its two floats collapsed.[12]
On 6 June 1905,Gabriel Voisin took off and landed on the RiverSeine with a towed kite glider on floats. The first of his unpowered flights was 140 metres (150 yd).[12] He later built a powered floatplane in partnership withLouis Blériot, but the machine was unsuccessful.[citation needed]
Other pioneers also attempted to attach floats to aircraft in Britain, Australia, France, and the US.[citation needed]
The FrenchmanAlphonse Pénaud filed the first patent for a flying machine with a boat hull and retractable landing gear in 1876, but AustrianWilhelm Kress is credited with building the first seaplane,Drachenflieger, in 1898, although its two 30 hp (22 kW) Daimler engines were inadequate for take-off, and it later sank when one of its two floats collapsed.[13]
On 6 June 1905,Gabriel Voisin took off and landed on the RiverSeine with a towed kite glider on floats. The first of his unpowered flights was 150 yards (140 m).[13] He later built a powered floatplane in partnership withLouis Blériot, but the machine was unsuccessful.
Other pioneers also attempted to attach floats to aircraft in Britain, Australia, France and the United States.
On 28 March 1910, FrenchmanHenri Fabre flew the first successful powered seaplane, theGnome Omega-poweredhydravion, a trimaranfloatplane.[14] Fabre's first successful take off and landing by a powered seaplane inspired other aviators, and he designed floats for several other flyers. The first hydro-aeroplane competition was held inMonaco in March 1912, featuring aircraft using floats from Fabre, Curtiss, Tellier and Farman. This led to the first scheduled seaplane passenger services, atAix-les-Bains, using a five-seat Sanchez-Besa from 1 August 1912.[13] TheFrench Navy ordered its first floatplane in 1912. On May 10, 1912Glenn L. Martin flew a homemade seaplane inCalifornia, settingrecords for distance and time.[15]
Curtiss A-1 seaplane in 1911
In 1911−12,François Denhaut constructed the first seaplane with a fuselage forming a hull, using various designs to givehydrodynamic lift at take-off. Its first successful flight was on 13 April 1912.[13]Throughout 1910 and 1911, American pioneering aviatorGlenn Curtiss developed his floatplane into the successfulCurtiss Model D land-plane, which used a larger central float and sponsons. Combining floats with wheels, he made the first amphibian flights in February 1911 and was awarded the firstCollier Trophy for US flight achievement. From 1912, his experiments with a hulled seaplane resulted in the 1913Model E and Model F, which he called "flying-boats".[13] In February 1911, theUnited States Navy took delivery of theCurtiss Model E and soon tested landings on and take-offs from ships, using the Curtiss Model D.
There were experiments by aviators to adapt theWright Model B to a water landing. The first motion picture recorded from an airplane was from a Wright Model B floatplane, byFrank Coffyn in 1911. The Wright Brothers, widely celebrated for their breakthrough aircraft designs, were slower to develop a seaplane; Wilbur died in 1912, and the company was bogged down in lawsuits. However, by 1913, the Wright Brother company developed the Wright Model CH Flyer.[16] In 1913, the Wright company also came out withe Wright Model G Aerboat, which was a seaplane with an enclosed cabin (a first for the company);the chief engineer of this version wasGrover Loening.[17]
In Britain, Captain Edward Wakefield andOscar Gnosspelius began to explore the feasibility of flight from water in 1908. They decided to make use ofWindermere in theLake District, England's largestlake. In 1909, the duo attended the Blackpool Aviation Week, where Wakefield “put forward the theory of flying from water, but was ridiculed by the experts.”[18] The rejection spurred the two men into collaborating on their own individual hydro aeroplane designs. To test their floatplanes, they decided to make use ofWindermere in theLake District—England's largestlake. Gnosspelius’ first attempts to fly attracted large crowds, although the aircraft, named Gnosspelius No.1, failed to take off due to its underpowered engines.[19] The unsuccessful demonstration prompted Gnosspelius to re-design the floats that had been crafted for him by boat builders Borwick & Sons, and had incorporated features of Borwick's successful speed-boat hulls. Meanwhile, Wakefield ordered a floatplane similar to the design of the 1910 Fabre Hydravion. Meanwhile, Wakefield ordered a floatplane similar to the design of the 1910 Fabre Hydravion. By November 1911, both Gnosspelius and Wakefield had aircraft capable of flight from water and awaited suitable weather conditions. Gnosspelius's flight was short-lived, as the aircraft crashed into the lake. Wakefield's pilot, however, taking advantage of a light northerly wind, successfully took off and flew at a height of 50 feet (15 m) to Ferry Nab, where he made a wide turn and returned for a perfect landing on the lake's surface. By November 1911, both Gnosspelius and Wakefield had aircraft capable of flight from water, and awaited suitable weather conditions. Gnosspelius's flight was short-lived, as the aircraft crashed into the lake. Conversely, Wakefield's pilot took advantage of a light northerly wind, and successfully took off and flew at a height of 50 feet to Ferry Nab, where he made a wide turn and returned for a perfect landing on the lake's surface.[citation needed]
In Switzerland,Émile Taddéoli equipped theDufaux 4 biplane with swimmers and successfully took off in 1912. A seaplane was used during theBalkan Wars in 1913, when a Greek "Astra Hydravion" did a reconnaissance of the Turkish fleet and dropped four bombs.[20][21]
American businessmanRodman Wanamaker became determined that the prize should go to an American aircraft and commissioned theCurtiss Aeroplane and Motor Company to design and build an aircraft capable of making the flight. Curtiss's development of theFlying Fish flying boat in 1913 brought him into contact withJohn Cyril Porte, a retiredRoyal Navy Lieutenant, aircraft designer and test pilot who was to become an influential British aviation pioneer. Recognising that many of the early accidents were attributable to a poor understanding of handling while in contact with the water, the pair's efforts went into developing practical hull designs to make the transatlantic crossing possible.[22]
The two years before World War I's breakout also saw the privately produced pair ofBenoist XIV biplane flying boats, designed byThomas W. Benoist, initiate the start of the first heavier-than-air airline service anywhere in the world, and the first airline service of any kind at all in the United States.[23][24]
At the same time, the British boat-building firmJ. Samuel White ofCowes on theIsle of Wight set up a new aircraft division and produced a flying boat in the United Kingdom. This was displayed at the London Air Show at Olympia in 1913.[25] In that same year, a collaboration between the S. E. Saunders boatyard ofEast Cowes and theSopwith Aviation Company produced the "Bat Boat", an aircraft with aconsuta laminated hull that could operate from land or on water, which today is called anamphibious aircraft.[25] The "Bat Boat" completed several landings on sea and on land and was duly awarded theMortimer Singer Prize.[25] It was the first all-British aeroplane capable of making six return flights over five miles within five hours.
In the US, Wanamaker's commission built on Glen Curtiss's previous development and experience with theCurtiss Model F[26] for the U.S. Navy, which rapidly resulted in theAmerica, designed under Porte's supervision following his study and rearrangement of the flight plan; the aircraft was a conventionalbiplane design with two-bay, unstaggered wings of unequal span with two pusherinline engines mounted side-by-side above thefuselage in the interplane gap. Wingtip pontoons were attached directly below the lower wings near their tips. The design (later developed into theModel H) resembled Curtiss's earlier flying boats but was built considerably larger so it could carry enough fuel to cover 1,100 mi (1,800 km). The three crew members were accommodated in a fully enclosed cabin.
Trials of theAmerica began 23 June 1914 with Porte also as Chief Test Pilot; testing soon revealed serious shortcomings in the design; it was under-powered, so the engines were replaced with more powerful tractor engines. There was also a tendency for the nose of the aircraft to try to submerge as engine power increased while taxiing on water. This phenomenon had not been encountered before, since Curtiss's earlier designs had not used such powerful engines nor large fuel/cargo loads and so were relatively more buoyant. In order to counteract this effect, Curtiss fittedfins to the sides of the bow to add hydrodynamic lift, but soon replaced these withsponsons, a type of underwater pontoon mounted in pairs on either side of a hull. These sponsons (or their engineering equivalents) and the flared, notched hull would remain a prominent feature of flying-boat hull design in the decades to follow. With the problem resolved, preparations for the crossing resumed. While the craft was found to handle "heavily" on takeoff, and required rather longer take-off distances than expected, thefull moon on 5 August 1914 was selected for the trans-Atlantic flight; Porte was to pilot theAmerica withGeorge Hallett as co-pilot and mechanic.
Curtiss NC Flying Boat "NC-3" skims across the water before takeoff, 1919
In 1913, theDaily Mail newspaperput up a £10,000 prize for thefirst non-stop aerial crossing of the Atlantic which was soon "enhanced by a further sum" from the Women's Aerial League of Great Britain. American businessmanRodman Wanamaker became determined that the prize should go to an American aircraft and commissioned theCurtiss Aeroplane and Motor Company to design and build an aircraft capable of making the flight. Curtiss' development of theFlying Fish flying boat in 1913 brought him into contact withJohn Cyril Porte, a retiredRoyal Navy lieutenant, aircraft designer and test pilot who was to become an influential British aviation pioneer. Recognising that many of the early accidents were attributable to a poor understanding of handling while in contact with the water, the pair's efforts went into developing practical hull designs to make the transatlantic crossing possible.[27]
At the same time the British boat building firmJ. Samuel White ofCowes on theIsle of Wight set up a new aircraft division and produced a flying boat in the United Kingdom. This was displayed at the London Air Show at Olympia in 1913.[25][page needed] In that same year, a collaboration between the S. E. Saunders boatyard ofEast Cowes and theSopwith Aviation Company produced the "Bat Boat", an aircraft with aconsuta laminated hull that could operate from land or on water, which today we call anamphibious aircraft.[25] The "Bat Boat" completed several landings on sea and on land and was duly awarded theMortimer Singer Prize.[25] It was the first all-British aeroplane capable of making six return flights over five miles within five hours.[citation needed]
In the U.S. Wanamaker's commission built on Glen Curtiss' previous development and experience with the Model F[28] for the U.S. Navy which rapidly resulted in theAmerica, designed under Porte's supervision following his study and rearrangement of the flight plan; the aircraft was a conventionalbiplane design with two-bay, unstaggered wings of unequal span with two pusherinline engines mounted side-by-side above thefuselage in the interplane gap. Wingtip pontoons were attached directly below the lower wings near their tips. The design (later developed into theModel H), resembled Curtiss' earlier flying boats, but was built considerably larger so it could carry enough fuel to cover 1,100 mi (1,800 km). The three crew members were accommodated in a fully enclosed cabin.[citation needed]
Trials of theAmerica began on 23 June 1914 with Porte also as Chief Test Pilot; testing soon revealed serious shortcomings in the design; it was under-powered, so the engines were replaced with more powerful engines mounted in a tractor configuration. There was also a tendency for the nose of the aircraft to try to submerge as engine power increased while taxiing on water. This phenomenon had not been encountered before, since Curtiss' earlier designs had not used such powerful engines nor large fuel/cargo loads and so were relatively more buoyant. In order to counteract this effect, Curtiss fittedfins to the sides of the bow to add hydrodynamic lift, but soon replaced these withsponsons, a type of underwater pontoon mounted in pairs on either side of a hull. These sponsons (or their engineering equivalents) and the flared, notched hull would remain a prominent feature of flying boat hull design in the decades to follow. With the problem resolved, preparations for the crossing resumed. While the craft was found to handle "heavily" on takeoff, and required rather longer take-off distances than expected, thefull moon on 5 August 1914 was selected for the trans-Atlantic flight; Porte was to pilot theAmerica withGeorge E. A. Hallett as co-pilot and mechanic.[citation needed]
Curtiss and Porte's plans were interrupted by the outbreak of World War I. Porte sailed for England on 4 August 1914 and rejoined the Navy as a member of theRoyal Naval Air Service. Appointed Squadron Commander ofRoyal Navy Air Station Hendon, he soon convinced the Admiralty of the potential of flying boats and was put in charge of thenaval air station atFelixstowe in 1915. Porte persuaded theAdmiralty to commandeer (and later, purchase) theAmerica and a sister craft from Curtiss. This was followed by an order for 12 more similar aircraft, one Model H-2 and the remaining asModel H-4s. Four examples of the latter were assembled in the UK bySaunders. All of these were similar to the design of theAmerica and, indeed, were all referred to asAmericas in Royal Navy service. The engines, however, were changed from the under-powered 160 hp Curtiss engines to 250 hpRolls-Royce Falcon engines. The initial batch was followed by an order for 50 more (totalling 64Americas overall during the war).[22] Porte also acquired permission to modify and experiment with the Curtiss aircraft.
The Curtiss H-4s were soon found to have a number of problems; they were underpowered, their hulls were too weak for sustained operations, and they had poor handling characteristics when afloat or taking off.[29][30] One flying boat pilot, Major Theodore Douglas Hallam, wrote that they were "comic machines, weighing well under two tons; with two comic engines giving, when they functioned, 180 horsepower; and comic control, being nose heavy with engines on and tail heavy in a glide."[31]
At Felixstowe, Porte made advances in flying-boat design and developed a practical hull design with the distinctive "Felixstowe notch".[32]Porte's first design to be implemented in Felixstowe was theFelixstowe Porte Baby, a large, three-enginedbiplane flying boat, powered by one central pusher and two outboard tractorRolls-Royce Eagle engines.
Porte modified an H-4 with a new hull whose improved hydrodynamic qualities made taxiing, take-off and landing much more practical and called it theFelixstowe F.1.
Porte's innovation of the "Felixstowe notch" enabled the craft to overcome suction from the water more quickly and break free for flight much more easily. This made operating the craft far safer and more reliable. The "notch" breakthrough would soon after evolve into a "step", with the rear section of the lower hull sharply recessed above the forward lower hull section, and that characteristic became a feature of both flying-boat hulls and seaplane floats. The resulting aircraft would be large enough to carry sufficient fuel to fly long distances and could berth alongside ships to take on more fuel.
Porte then designed a similar hull for the largerCurtiss H-12 flying boat which, while larger and more capable than the H-4s, shared failings of a weak hull and poor water handling. The combination of the new Porte-designed hull, this time fitted with two steps, with the wings of the H-12 and a new tail, and powered by twoRolls-Royce Eagle engines, was named the Felixstowe F.2 and first flew in July 1916,[33] proving greatly superior to the Curtiss on which it was based. It was used as the basis for all future designs.[34] It entered production as the Felixstowe F.2A, being used as a patrol aircraft, with about 100 being completed by the end of World War I. Another seventy were built, and these were followed by two F.2c, which were built at Felixstowe.
In February 1917, the first prototype of theFelixstowe F.3 was flown. It was larger and heavier than the F.2, giving it greater range and heavier bomb load, but poorer agility. Approximately 100 Felixstowe F.3s were produced before the end of the war.
TheFelixstowe F.5 was intended to combine the good qualities of the F.2 and F.3, with the prototype first flying in May 1918. The prototype showed superior qualities to its predecessors but, to ease production, the production version was modified to make extensive use of components from the F.3, which resulted in lower performance than the F.2A or F.5.
F.2, F.3, and F.5 flying boats were extensively employed by the Royal Navy for coastal patrols and to search for GermanU-boats.In 1918, they were towed on lighters towards the northern German ports to extend their range; on 4 June 1918, this resulted in three F.2As engaging in a dogfight with ten German seaplanes, shooting down two confirmed and four probables at no loss.[22] As a result of this action, British flying boats weredazzle-painted to aid identification in combat.
TheCurtiss Aeroplane and Motor Company independently developed its designs into the small Model F, the larger Model K (several of which were sold to the Russian Naval Air Service), and the Model C for the U.S. Navy. Curtiss, among others, also built the Felixstowe F.5 as theCurtiss F5L, based on the final Porte hull designs and powered by AmericanLiberty engines.
Meanwhile, the pioneering flying-boat designs of François Denhaut had been steadily developed by theFranco-British Aviation Company into a range of practical craft. Smaller than the Felixstowes, several thousand FBAs served with almost all of the Allied forces as reconnaissance craft, patrolling the North Sea, Atlantic and Mediterranean Oceans.
In Italy, several seaplanes were developed, starting with the L series and progressing with the M series. TheMacchi M.5, in particular, was extremely manoeuvrable and agile and matched the land-based aircraft it had to fight. Two hundred forty-four were built in total.Towards the end of World War I, the aircraft were flown by Italian Navy Aviation, United States Navy and United States Marine Corps airmen. Ensign Charles Hammann won the first Medal of Honor awarded to a United States naval aviator in an M.5
Curtiss NC Flying Boat "NC-3" skims across the water before takeoff, 1919Supermarine Southamptons, 1925Consolidated flying boat produced for Japan, which evaluated the type in the 1930s
A CurtissNC-4 became the first aircraft to fly across the Atlantic Ocean in 1919, crossing via theAzores. Of the four that made the attempt, only one completed the flight.[36][37] Before the development of highly reliable aircraft, the ability to land on water was a desirable safety feature for transoceanic travel.[38]
During the 1920s, theRoyal Air Force (RAF) Far East flight performed a series of "showing the flag" long-distance formation flights using the newly developedSupermarine Southampton. Perhaps the most notable of these flights was a 43,500 km (27,000 mi) expedition conducted during 1927 and 1928; it was carried out by four Southamptons of theFar East Flight, setting out from Felixstowe via the Mediterranean and India toSingapore.[39] Both the RAF and Supermarine acquired considerable acclaim from these flights, as well as proving that flying boats had evolved to become reliable means of long-distance transport.[40]
In 1923, the first successful commercial flying boat service was introduced with flights to and from theChannel Islands. The British aviation industry was experiencing rapid growth. The Government decided that nationalization was necessary and ordered five aviation companies to merge to form the state-ownedImperial Airways of London (IAL). IAL became the internationalflag-carrying British airline, providing flying boat passenger and mail transport links between Britain andSouth Africa using aircraft such as theShort S.8 Calcutta.[41]
In 1928, fourSupermarine Southampton flying boats of theRAF Far East flight arrived inMelbourne,Australia. The flight was considered proof that flying boats had become a reliable means of long-distance transport.
In the 1930s, flying boats made it possible to have regular air transport between the U.S. and Europe, opening up new air travel routes to South America, Africa, and Asia.Foynes,Ireland andBotwood,Newfoundland and Labrador were the terminals for many early transatlantic flights. In areas where there were no airfields for land-based aircraft, flying boats could stop at small river, lake or coastal stations to refuel and resupply. ThePan AmBoeing 314 "Clipper" flying boats brought new exotic destinations like the Far East within reach and came to represent the romance of flight.
By 1931, mail from Australia was reaching Britain in just 16 days – less than half the time taken by sea. In that year, government tenders on both sides of the world invited applications to run new passenger and mail services between the ends of theBritish Empire, andQantas and IAL were successful with a joint bid. A company under combined ownership was then formed, Qantas Empire Airways. The new ten-day service betweenRose Bay, New South Wales (nearSydney), andSouthampton was such a success with letter-writers that before long the volume of mail was exceeding aircraft storage space.[citation needed]
A better solution to the problem was sought by the British government during the early 1930s, who released a specification calling for a new large aircraft capable of carrying up to 24 passengers in spacious comfort along with adequate room forairmail or freight while simultaneously being capable of acruising speed of 170 mph and a range of at least 700 miles; the capacity for an extended range of 2,000 miles to serve theNorth Atlantic route was also stipulated.[42] Originally intended for use by IAL, partner Qantas agreed to the initiative and undertook to purchase six of the newShort S23 "C" class or "Empire" flying boats as well. Being ordered from aviation manufacturerShort Brothers, the Empire was reportedly hailed as being "one of the world's boldest experiments in aviation", while early sceptics referred to the order less favourably as being a 'gamble'.[42] IAL were so impressed by the Empire that it placed a follow-on order for another 11; when combined with the original order for 28 flying boats, this was the largest single order to have ever been placed for a British civil aircraft at that time.[43]
Dornier Do X over a seaport town in the Baltic, 1930"Maia and Mercury", just before the first trans-Atlantic flight, August 1938
Delivering the mail as quickly as possible generated a lot of competition and some innovative designs. One variant of the Short Empire flying boats was the strange-looking "Maia and Mercury". It was a four-enginedfloatplane "Mercury" (the winged messenger) fixed on top of "Maia", a heavily modified Short Empire flying boat.[25] The larger Maia took off, carrying the smaller Mercury loaded to a weight greater than it could take off with. This allowed the Mercury to carry sufficient fuel for a direct trans-Atlantic flight with the mail.[44] Unfortunately this was of limited usefulness, and the Mercury had to be returned from America by ship. The Mercury did set a number of distance records beforein-flight refuelling was adopted.[45]
Sir Alan Cobham devised a method of in-flight refuelling in the 1930s. In the air, the Short Empire could be loaded with more fuel than it could take off with.[25] Short Empire flying boats serving the trans-Atlantic crossing were refueled over Foynes; with the extra fuel load, they could make a direct trans-Atlantic flight. AHandley Page H.P.54 Harrow was used as the fuel tanker.[25]
The GermanDornier Do X flying boat was noticeably different from its UK and U.S.-built counterparts.[46] It had wing-like protrusions from the fuselage, calledsponsons, to stabilize it on the water without the need for wing-mounted outboard floats. This feature was pioneered byClaudius Dornier during the First World War on his Dornier Rs. I giant flying boat, and perfected on theDornier Wal in 1924. The enormous Do X was powered by 12 engines and once carried 170 persons as a publicity stunt.[25] It flew to America in 1930–31,[25] crossing the Atlantic via an indirect route over 9 months. It was the largest flying boat of its time, but was severely underpowered and was limited by a very low operational ceiling. Only three were built, with a variety of different engines installed, in an attempt to overcome the lack of power. Two of these were sold to Italy.[citation needed]
TheDornier Wal was "easily the greatest commercial success in the history of marine aviation".[47] Over 250 were built in Italy, Spain, Japan, The Netherlands and Germany. Numerous airlines operated the Dornier Wal on scheduled passenger and mail services.[48] Wals were used by explorers, for a number of pioneering flights, and by the military in many countries. Though having first flown in 1922, from 1934 to 1938 Wals operated the over-water sectors of theDeutsche Luft Hansa South Atlantic Airmail service.[49][50]
The Boeing 314 Clipper, was important for opening long distance airline routes and during WW2 they were used for transport
The military value of flying boats was well recognized, and every country bordering on water operated them in a military capacity at the outbreak of theSecond World War. Flying boats such as thePBM Mariner patrol bomber,PBY Catalina,Short Sunderland, andGrumman Goose were procured in large numbers. The Sunderland, which was developed in parallel to the civilian Empire flying boat, was one of the most powerful and widely used flying boats throughout the conflict,[51][52] while Catalinas were one of the most produced ASW of the war, with over 2,661 being produced in the US alone.[53][54]
On 3 April 1940, a single Sunderland operating offNorway was attacked by six GermanJunkers Ju 88C fighters; during the engagement, it shot one down and damaged another until it retreated and drove off the rest. The Germans reputedly nicknamed the Sunderland theFliegendes Stachelschwein ("Flying Porcupine") due to its defensive firepower.[59][60] Sunderlands in the Mediterranean theatre proved themselves on multiple high-profile occasions, flying many evacuation missions during theGerman seizure ofCrete, each carrying as many as 82 passengers. One Sunderland flew the reconnaissance mission to observe the Italian fleet at anchor inTaranto before the famousRoyal NavyFleet Air Arm'storpedo attack on 11 November 1940.[61]
The largest flying boat of the war was theBlohm & Voss BV 238, which was also the heaviest plane to fly during the Second World War and the largest aircraft built and flown by any of theAxis powers. Only the first prototype ever flew, commencing flight trials in April 1944.[62] Months later, it wasstrafed and partially sunk while moored onLake Schaal, to the east ofHamburg; it never returned to flight, instead being intentionally sunk in deep water after the end of the conflict.[63]
TheImperial Japanese Navy operated what has been often described as the best flying boat of the conflict, theKawanishi H8K.[64][65][66] Its design was based upon its immediate predecessor, theKawanishi H6K, but was a considerably larger and longer-ranged aircraft designed at the request of the Navy just prior to the outbreak of war.[67][68] On the night of 4 March 1942, two H8Ks conducted thesecond raid on Pearl Harbor, refuelling en route bysubmarine atFrench Frigate Shoals in order to achieve the necessary range; poor visibility caused this attack on Pearl Harbor to fail to accomplish any significant damage.[69][70] An improved H8K2 variant of the type, featuring extremely heavy defensive armament, was also introduced.[71]
The Martin Company produced the prototypeXPB2M Mars based on their PBM Mariner patrol bomber, with flight tests between 1941 and 1943. The Mars was converted by the Navy into a transport aircraft designated the XPB2M-1R. Satisfied with the performance, 20 of the modified JRM-1 Mars were ordered. The first of the five production Mars flying boats entered service ferrying cargo toHawaii and the Pacific Islands on 23 January 1944.[73] Following the end of the conflict, the Navy opted to scaled back their order, buying only the five aircraft. The five Mars were completed, and the last delivered in 1947.[74]
The U.S. used several 4-engine flying boats during World War II, including those that had been operating as civilian airliners. This included fiveBoeing B-314 Clippers, four more as the C-98s; twoMartin M-130 Clippers,a Martin XPB2M-1/XPB2M-1R prototype, and oneJRM-1 Mars; threeSikorsky VS-44s (JR2S-1). However, the main 4-engined flying boat of the U.S. forces was thePB2Y Coronado, of which nearly 220 were used in several versions:maritime patrol, bombing, medical/hospital transport, and for regular cargo; it also served with British forces in theBattle for the Atlantic.[75]
One of the features of flying boats that was useful for search and rescue, was the ability to land on the water and not only pull out people from the water but stay there. One of the famous cases of this was the sinking of theIndianapolis, which went down on 31 July 1945, leaving hundreds of sailors in the water. Once it was realized it was missing, it was searched for, and the first to arrive was an amphibiousPBY-5A Catalina patrol plane flown by Lieutenant Commander (USN)Robert Adrian Marks. Marks and his flight crew spotted the survivors and dropped life rafts; one raft was destroyed by the drop, while others were too far away from the exhausted crew. Against standing orders not to land in the open ocean, given the unique situation and lives at risk, Marks took a vote of his crew and decided to land the aircraft in twelve-foot (3.7 m) swells. He was able to maneuver his craft to pick up 56 survivors. Space in the plane was limited, so Marks had men lashed to the wing with parachute cord. The aircraft was unflyable with so many on it but could still float. This protected many of the exhausted men from being eaten by sharks or drowning while waiting for the main rescue force to arrive. After nightfall, the destroyer escortUSS Cecil J. Doyle, the first of seven rescue ships, used its searchlight as a beacon and instilled hope in those still in the water.Cecil J. Doyle and six other ships picked up the remaining survivors. After the rescue, the PBY was sunk byCecil J. Doyle to scuttle it.[76]
After the end of the Second World War, the use of flying boats rapidly declined for several reasons. The ability to land on water became less of an advantage owing to the considerable increase in the number and length of land based runways during the conflict. Furthermore the commercial competitiveness of flying boats diminished, as their design compromised aerodynamic efficiency and speed in order to accommodate waterborne takeoff and landing. New land-based airliners such as theLockheed Constellation andDouglas DC-4 were developed with comparable reliability, speed, and long-range. The new landplanes were relatively easy to fly, and did not require the extensive pilot training programs mandated for seaplane operations. One of the 314's most experienced pilots said, "We were indeed glad to change to DC-4s, and I argued daily for eliminating all flying boats. The landplanes were much safer. No one in the operations department ... had any idea of the hazards of flying boat operations. The main problem now was lack of the very high level of experience and competence required of seaplane pilots".[77]
TheHughes H-4 Hercules, in development in the U.S. during the war, was even larger than the BV 238 but it did not fly until 1947. TheSpruce Goose, as the 180-ton H-4 was nicknamed, was the largest flying boat ever to fly. Carried out during Senate hearings into Hughes' use of government funds on its construction, the short hop of about a mile at 70 ft above the water by the "Flying Lumberyard" was claimed by Hughes as the H-4's vindication.[78][79] Cutbacks in expenditure after the war and the disappearance of its intended mission as a transatlantic transport left the H-4 with no purpose. Despite never flying again, a full-time crew of 300 workers maintained the H-4 in a flightworthy condition in a climate-controlled hangar up until Hughes' death in 1976.[80][81]
In early 1944, the BritishAir Ministry issued a contract for the production of a smalljet-powered flying boat, theSaunders-Roe SR.A/1, that was intended for use as anair defence aircraft optimised for use in the Pacific theatre.[82] By adopting jet propulsion for the flying boat, it was possible to design it with a hull, rather than making it afloatplane, and thus eliminating the performance handicaps typically imposed upon floatplanes. It was projected to be capable of attaining speeds of up to 520 mph at 40,000 ft.[82] Due to the SR.A/1's perceived value in the war against Imperial Japan, measures taken at an early stage of development towards immediate quantity production.[83] However, due to the end of the conflict, pressure for the SR.A/1 quickly dissipated.[83]
On 16 July 1947, the SR.A/1 prototype performed its maiden flight, quickly proving its soundness in terms of its performance and handling.[84] However, officials judged that such an aircraft was unnecessary, and that the aircraft carrier had demonstrated a far more effective way to project airpower over the oceans.[85] During late 1950, shortly after the outbreak of theKorean War, interest in the SR.A/1 programme was briefly resurrected amongst British and American officials, with whom data had been shared in the project.[83] However, the flying boat fighter was found to be obsolete in comparison to increasingly capable land-based fighters, leading to a second and final cancellation.[86][87]
During theBerlin Airlift (which lasted from June 1948 until August 1949) tenSunderlands and twoHythes were used to transport goods fromFinkenwerder on theElbe nearHamburg to isolated Berlin, landing on the Havelsee besideRAF Gatow until it iced over.[88] The Sunderlands were particularly used for transporting salt, as their airframes were already protected against corrosion from seawater. Transporting salt in standard aircraft risked rapid and severe structural corrosion in the event of a spillage. In addition, threeAquila Airways flying boats were used during the airlift.[25]Bucking the trend, in 1948 Aquila Airways was founded to serve destinations that were still inaccessible to land-based aircraft.[25] This company operatedShort S.25 andShort S.45 flying boats out of Southampton on routes toMadeira,Las Palmas,Lisbon,Jersey,Mallorca,Marseille,Capri,Genoa,Montreux andSanta Margherita.[25] From 1950 to 1957, Aquila also operated a service fromSouthampton toEdinburgh andGlasgow.[25] The flying boats of Aquila Airways were also chartered for one-off trips, usually to deploy troops where scheduled services did not exist or where there were political considerations. The longest charter, in 1952, was from Southampton to theFalkland Islands.[25] In 1953, the flying boats were chartered for troop deployment trips toFreetown andLagos and there was a special trip fromKingston upon Hull toHelsinki to relocate a ship's crew.[25] The airline ceased operations on 30 September 1958.[25]
Saunders-Roe PrincessG-ALUN at the Farnborough SBAC Show in September 1953
On 22 August 1952, theSaunders-Roe Princess, one of the largest and luxurious flying boats ever developed, performed its maiden flight.[89] While flight testing of the innovative and ambitious flying boat went relatively smoothly, determining that the Princess was indeed capable of achieving its envisioned performance figures, only one prototype of the type would ever fly.[90][89] Despite the granting of acertificate of airworthiness and representing the pinnacle of flying boat development of the era, no customers were willing to place firm orders for the Princess. This is despite reports that several would-be operators, includingAquila Airways andAero Spacelines, had attempted to purchase examples.[25][91][92]
In 1951, BOAC performed an in-depth reevaluation of its standing requirements, and determined that the airline had no present need for the Princess, or any new large flying boat. The airline had already chosen to terminate its existing flying boat services during the previous year.[89] Up until 1974,Ansett Australia operated a flying boat service from Rose Bay toLord Howe Island usingShort Sandringhams.[citation needed]
The US Navy continued to operate flying boats (notably theMartin P5M Marlin) until the late 1960s. During the 1950s, the US Navy had encouraged the development of a jet-powered flying boat bomber, theMartin P6M Seamaster; however, its development was protracted by unfavourable handling characteristics above Mach 0.8, including rapid changes in directional trim, severebuffeting, and wing drop, which made it unfeasible for service until these tendencies were rectified.[93] Following the US Navy's withdrawal of support, Martin tried unsuccessfully to market the SeaMaster to the civilian market, rebranding it as theSeaMistress, but the initiative picked up no takers.[94]
During the 1950s, the Japanese aircraft manufacturerShinMeiwa Industries conducted internal design studies into developing flying boats that would exhibit greater levels of seaworthiness than their predecessors.[95] Over the following decade, the company developed theShin Meiwa US-1A, a new generation flying boat, to meet Japan's requirement for a maritime patrol aircraft capable of ASW operations. The initial model, designatedPS-1, was quickly followed by a dedicatedsearch-and-rescue (SAR) variant, theUS-1, although this was technically an amphibian rather than a flying boat through its modified designs.[95] Shin Meiwa developed further flying boat concepts around this period, including theShin Meiwa MS (Medium Seaplane) a 300-passenger long-range flying boat with its own beaching gear; and the gargantuanShin Meiwa GS (Giant Seaplane) with a capacity of 1200 passengers seated on three decks.[96]
The U.S. Navy continued to operate flying boats (notably theMartin P5M Marlin) until the early 1970s. The Navy even experimented with theMartin Seamaster jet-powered seaplane bomber, as well as theConvair F2Y Sea Dart supersonic interceptor.
The U.S. Coast Guard operatedHU-16 Albatross (affectionately known as the 'goat') well into the 1980s, retiring them as the airframes clocked out their flying 11 thousand flying hours. About twenty were still in service in the 1970s, and the last operation flight was in 1983. The aircraft was very popular with the Coast Guard due to its unique capabilities compared to other types, and was noted for its versatility, range, and ability to land on water which was especially useful for water rescues.[97]
On 18 December 1990, Pilot Tom Casey completed the first round-the-world flight in a floatplane with only water landings using aCessna 206 named Liberty II.[98]
TheShinMaywa US-2 is a largeSTOL amphibious aircraft designed for air-sea rescue work, derived from the earlier US-1. The first example was delivered to theJapan Maritime Self Defense Force in 2009; the service has replaced its US-1 fleet with the US-2.[99] A civilian-orientated fire-fighting variant of the US-2 has also been designed and promoted to prospective customers.[100]
TheCanadair CL-415, an improved model of theCanadair CL-215, remains in production during the twenty-first century.[101][102] The type has been primarily used for forest fire suppression, but has also seen use in other capacities, such as a maritime patrol aircraft.[103][104] The German companyDornier Seawings, an off-shoot of the original Dornier company, has repeatedly announced plans to launch production of itsSeaStar composite flying boat.[105][106] In February 2016, Dornier launched the improved CD2 SeaStar.[107]
Many modern civilian aircraft have a floatplane variant, usually as utility transports to lakes and other remote areas. Most of these are offered as third-party modifications under asupplemental type certificate (STC), although there are several aircraft manufacturers that build floatplanes from scratch, and a few that continue to buildflying boats. Some older flying boats remain in service for firefighting duty, as well as theCanadair CL-415 which remains in production as of 2022, andChalk's Ocean Airways operated a fleet of Grumman Mallards in passenger service until service was suspended after acrash on December 19, 2005, which was linked to maintenance, not to design of the aircraft. Purely water-based seaplanes have largely been supplanted by amphibious aircraft.Seaplanes can only take off and land on water with little or nowave action and, like other aircraft, have trouble in extreme weather. The size of waves a given design can withstand depends on, among other factors, the aircraft's size, hull or float design, and its weight, all making for a much more unstable aircraft, limiting actual operational days. Flying boats can typically handle rougher water and are generally more stable than floatplanes while on the water.
Seaplanes are also used in remote areas such as theAlaskan andCanadian wilderness, especially in areas with a large number oflakes convenient for takeoff and landing. They may operate on acharter basis, provide scheduled service, or be operated by residents of the area for personal use. There are seaplane operators that offer services between islands such as in theCaribbean Sea or theMaldives. Usually these are converted from reliable commercial models, and fitted for floats.
One floatplane conversion under consideration in the 2020s is a floatplane version of theC-130 for special military applications.[112]
Floatplanes allow access to most remote aquatic locations
SinceWorld War II and the advent of helicopters, advancedaircraft carriers and land-based aircraft, military seaplanes have stopped being used. This, coupled with the increased availability of civilian airstrips, has greatly reduced the number of flying boats being built. However, many modern civilian aircraft have floatplane variants, most offered as third-party modifications under asupplemental type certificate (STC), although there are several aircraft manufacturers that build floatplanes from scratch. These floatplanes have found their niche as one type ofbush plane, for light duty transportation to lakes and other remote areas as well as to small/hilly islands without proper airstrips. They may operate on acharter basis (including pleasure flights), provide scheduled service, or be operated by residents of the area for private, personal use.
^abcGunston, "The Cambridge Aerospace Dictionary", 2009.
^de Saint-Exupery, A. (1940). "Wind, Sand and Stars" p33, Harcourt, Brace & World, Inc.
^The Oxford English Dictionary defines "seaplane" as An aeroplane designed to be able to operate from water;specifically, one with floats, in contrast to a flying boat.
^James M. Triggs (Winter 1971). "Floatplane Flying".Air Trails: 39.
^TheOxford English Dictionary defines "seaplane" as "An aeroplane designed to be able to operate from water;specifically, one with floats, in contrast to a flying boat."
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^abcdeFlying Boats & Seaplanes: A History from 1905, Stéphane Nicolaou pp. 10, 15-17, 24
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