A sea plane is a fixed-wing aircraft capable of taking off and landing (alighting) on water. Seaplanes that can also take off and land on airfields are a subclass called amphibian aircraft. Seaplanes and amphibians are usually divided into two categories based on their technological characteristics: floatplanes and flying boats; the latter are generally far larger and can carry far more. These aircraft were sometimes called hydroplanes.
The word “seaplane” is used to describe two types of air/water vehicles: the floatplane and the flying boat.
A floatplane has slender pontoons, or floats, mounted under the fuselage. 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). These floats add to the empty weight of the airplane, and to the drag coefficient, resulting in reduced payload capacity, slower rate-of-climb, and slower cruise speed.
In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship’s hull in the water. Most flying boats have small floats mounted on their wings to keep them stable. Not all small seaplanes have been floatplanes, but most large seaplanes have been flying boats, their great weight supported by their hulls.
The term “seaplane” is used by some instead of “floatplane”. This is the standard British usage, which treats both flying boats and floatplanes as types of seaplane, in the US fashion.
An amphibious aircraft can take off and land both on conventional runways 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 production seaplanes are typically light aircraft, amphibious, and of a floatplane design.
The first manned and controlled (though unpowered) seaplane flight was established by French aircraft designer, builder and pilot Gabriel Voisin in June 1905, on the river Seine (Paris); it was a towed flight, at 15 to 20 m altitude (50 to 66 ft), and 600 meters (2000 ft) long. The aircraft was a biplane configuration with an aft tail and a front elevator, supported at rest by 2 planing floats (catamaran).
The first autonomous flight by a seaplane was made by the French engineer Henri Fabre in March 1910. Its name was Le Canard (‘the duck’), and took off from the water and flew 1,650 feet on its first flight on March 28, 1910. These experiments were closely followed by the aircraft pioneers Gabriel and Charles Voisin, who purchased several of the Fabre floats and fitted them to their Canard Voisin airplane. In October 1910, the Canard Voisin became the first seaplane to fly over the river Seine, and in March 1912, the first seaplane to be used in military exercises from a seaplane carrier, La Foudre (‘the lightning’).
In the United States, early development was carried out at Hammondsport, New York by Glenn Curtiss who had beaten Alexander Graham Bell and others in the Aerial Experiment Association. The first American seaplane flight occurred on January 26, 1911 by Curtiss in his “hydroaeroplane” from the waters of San Diego Bay.
In June 1911, in co-operation with Edouard Perrot (Edouard Perrot & Cie), Emile Taddéoli started to design the seaplane “La Mouette” in Switzerland, and before, began tests with a Dufaux 4 biplane equipped with swimmers. On March 26, 1912, a first takeoff was not successful, and “La Mouette” was destroyed. In summer 1912, René Grandjean replaced the skis of his aircraft by floats designed and engineered by himself, resulting in the first takeoff of a Swiss hydroplane (seaplane) on August 4, 1912. The first British seaplane flight, by Sydney Sippe, also took place in 1912.
The first in history combat missions of a seaplane was probably those of a Greek “Astra Hydravion” between December 1912 and January 1913, during the Balkan Wars. In one of them, on January 24, 1913, the seaplane with two Greek pilots flew at 1200 meters over the Dardanelles from the European to the Asian coast, did a reconnaissance of the Turkish fleet, dropped 4 bombs and after 2 hours flight landed at sea near the island of Imbros. The plane was targeted by canons and rifles unsuccessfully.
Englishman John Cyril Porte joined with Curtiss to design a transatlantic flying boat, and developed a more practical hull for Curtiss’ airframe and engines with the distinctive ‘step’ which enabled the hull and floats to cleanly break free of the water’s surface at take-off. In the UK the Curtiss flying boat was developed into the Felixstowe series of flying boats, which were used in the First World War to patrol for German submarines. Curtiss N-9 seaplanes were used during World War I as primary trainers, and over 2,500 Navy pilots learned to fly in them. A handful of N-9s were used in the Hewitt-Sperry Automatic Airplane project to develop an “aerial torpedo” or flying bomb, an early RPV. flathead lake tours