Flying Boats

A flying boat is a fixed-winged seaplane with a hull, allowing it to land on water, that usually has no type of landing gear to allow operation on land. It differs from a floatplane 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 (called sponsons) from the fuselage. Flying boats were some of the largest aircraft of the first half of the 20th century, exceeded in size only by bombers developed during World War II. Their advantage lay in using water instead of expensive land-based runways, making them the basis for international airlines in the interwar period. They were also commonly used for maritime patrol and air-sea rescue.
Their use gradually trailed off after World War II, partially because of the investments in airports during the war. In the 21st century, flying boats maintain a few niche uses, such as dropping water on forest fires, air transport around archipelagos, 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.

In September 1919 British company Supermarine started operating the first flying boat service in the world, from Woolston to Le Havre in France, but it was short-lived.

A Curtiss NC-4 became the first aircraft to fly across the Atlantic Ocean in 1919, crossing via the Azores. Of the four that made the attempt, only one completed the flight. Before the development of highly reliable aircraft, the ability to land on water was a desirable safety feature for transoceanic travel.

In 1923, the first successful commercial flying boat service was introduced with flights to and from the Channel 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-owned Imperial Airways of London (IAL). IAL became the international flag-carrying British airline, providing flying boat passenger and mail transport links between Britain and South Africa using aircraft such as the Short S.8 Calcutta.

In 1928, four Supermarine Southampton flying boats of the RAF Far East flight arrived in Melbourne, Australia. The flight was considered proof that flying boats had evolved to become 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 and Botwood, Newfoundland and Labrador were the termini for many early transatlantic flights. In areas where there were no airfields for land-based aircraft, flying boats could stop at small island, river, lake or coastal stations to refuel and resupply. The Pan Am Boeing 314 "Clipper" planes brought exotic destinations like the Far East within reach of air travelers 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 the British Empire, and Qantas and IAL were successful with a joint bid. A company under combined ownership was then formed, Qantas Empire Airways. The new ten-day service between Rose Bay, New South Wales (near Sydney) and Southampton was such a success with letter-writers that before long the volume of mail was exceeding aircraft storage space.
A solution to the problem was found by the British government, who in 1933 had requested aviation manufacturer Short Brothers to design a big new long-range monoplane for use by IAL. Partner Qantas agreed to the initiative and undertook to purchase six of the new Short S23 "C" class or "Empire" flying boats.

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-engined floatplane "Mercury" (the winged messenger) fixed on top of "Maia", a heavily modified Short Empire flying boat. 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. 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 before in-flight refuelling was adopted.


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. 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. A Handley Page H.P.54 Harrow was used as the fuel tanker.
The German Dornier Do X flying boat was noticeably different from its UK and U.S.-built counterparts. It had wing-like protrusions from the fuselage, called sponsons, to stabilize it on the water without the need for wing-mounted outboard floats. This feature was pioneered by Claudius Dornier during World War I on his Dornier Rs. I giant flying boat, and perfected on the Dornier Wal in 1924. The enormous Do X was powered by 12 engines and once carried 170 persons as a publicity stunt. It flew to America in 1930-31, 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.
The Dornier Wal was "easily the greatest commercial success in the history of marine aviation". Over 250 were built in Italy, Spain, Japan, The Netherlands and Germany. Numerous airlines operated the Dornier Wal on scheduled passenger and mail services. 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 the Deutsche Luft Hansa South Atlantic Airmail service.

Flying boats today

The shape of the Short Empire, a British flying boat of the 1930s was a harbinger of the shape of 20th century aircraft yet to come. Today, however, true flying boats have largely been replaced by seaplanes with floats and amphibian aircraft with wheels. The Beriev Be-200 twin-jet amphibious aircraft has been one of the closest "living" descendants of the earlier flying boats, along with the larger amphibious planes used for fighting forest fires. There are also several experimental/kit amphibians such as the Volmer Sportsman, Quikkit Glass Goose, Airmax Sea Max, Aeroprakt A-24, and Seawind 300C.
 
The ShinMaywa US-2 is a large STOL amphibious aircraft designed for air-sea rescue work. The US-2 is operated by the Japan Maritime Self Defense Force. The Canadair CL-215 and successor Bombardier 415 are examples of modern flying boats and are used for forest fire suppression.
Dornier announced plans in May 2010 to build CD2 SeaStar composite flying boats in Quebec, Canada.
The Chinese state owned Aviation Industry Corporation of China is set to launch a massive new AVIC TA-600 amphibious airplane in 2016.
The ICON A5 is an amphibious aircraft in the light-sport class.