A floatplane has slender pontoons 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 ability to handle wave heights typically greater than 12 inches (0.31 m). These float pontoons 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.
The Hanriot HD.2 was a fighter aircraft produced in France during the First World War. The design was based on that of the HD.1, but the HD.2 was a purpose-built floatplane. It made use of enlarged tail surfaces and shorter wingspans with greater area. Like its predecessor, though, it was a conventional single-bay biplane with staggered wings of unequal span. The prototype had a twin pontoon undercarriage, with a small third pontoon under the tail. The third pontoon was later discarded on production machines, though.
The HD.2 was developed specifically as an interceptor to defend flying boat bases, but soon was used as an escort fighter to protect French reconnaissance flying boats. The United States Navy also bought 10 examples with wheeled undercarriages, designated HD.2C.
Both the French and United States navies used these aircraft in early experiments in launching fighters from warships. The United States Navy replicated the French trials where a HD.1 had been launched from a platform built atop one of the turrets of the battleship Paris and built a similar platform on the USS Mississippi to launch a HD.2 from. The French Navy converted some of their HD.2s to wheeled configuration and used them for trials on the new aircraft carrier Béarn.
A final experiment in launching a HD.2 from a ship was carried out in 1924 with two new-built examples designated H.29. An unorthodox launching system was developed where the aircraft were equipped with three small pulley-wheels, one on each tip of the upper wing, and one at the tip of the tail fin. These ran along metal rails that had been attached to project horizontally from the mast of the battleship Lorraine. This did not work as hoped, succeeding only in depositing the aircraft into the water below. Further trials were discontinued.
Some newer model Hanriot H.D.1s were supplied to the French Navy. Eventually a few of which were passed to the U.S. Navy. Some naval Hanriots were converted to, or built as, floatplanes. This model was fitted with enlarged tail surfaces. After the war ten Hanriot HD.1s were built (or possibly modified/converted) by the U.S. Naval Aircraft Factory. The U.S. Navy machines were mainly used as trainers, although they were also involved in experiments with takeoff platforms on warships. These Hanriots could be fitted with twin guns, and at least one machine had a hydrovane and flotation bags of the type developed for the Royal Navy
The SPAD S.XIV was a single-seat French biplane seaplane fighter aircraft built by Société Pour L'Aviation et ses Dérivés (SPAD) and flown by the French Navy during World War I. The SPAD XIV was a development of the SPAD XII. It was powered by a 149 kW (200hp) Hispano-Suiza 8 Bc engine. The S.XIV was similarly armed with the 37 mm cannon developed by SAMC for which 12 shots were carried. The cannon fired through the propellor shaft, necessitating the use of a geared Hispano-Suiza aviation engine to mount the gun. The SPAD XIV also carried a single 0.303 inch (7.7 mm) Vickers machine gun mounted on the starboard side of the nose. Fourty were constructed and flew in the French Navy during 1918.