Amphibious aircraft

An amphibious aircraft or amphibian is an aircraft that can take off and land on both land and water. Fixed-wing amphibious aircraft are seaplanes (flying boats and floatplanes) that are equipped with retractable wheels, at the expense of extra weight and complexity, plus diminished range and fuel economy compared to planes designed for land or water only. Some amphibians are fitted with reinforced keels which act as skis, allowing them to land on snow or ice with their wheels up.

CL-215T 43-21 (29733827710)
A Canadair CL-215T amphibian with retractable wheels

Design

Floatplanes often have floats that are interchangeable with wheeled landing gear (thereby producing a conventional land-based aircraft) however in cases where this is not practical amphibious floatplanes, such as the amphibious version of the DHC Otter, incorporate retractable wheels within their floats.

Many amphibian aircraft are of the flying boat type. These aircraft, and those designed as floatplanes with a single main float under the fuselage centerline (such as the Loening OL and Grumman J2F), require outrigger floats to provide lateral stability so as to avoid dipping a wingtip, which can destroy an aircraft if it happens at speed, or can cause the wingtip to fill with water and sink if stationary. While these impose weight and drag, amphibious aircraft also face the possibility of these getting hit when operating from a runway. A common solution is to make them retractable as those found on the Consolidated Catalina however these are even heavier than fixed floats. Some aircraft may have the tip floats removed for extended use from land. Other amphibians, such as the Dornier Seastar use stub wings called sponsons, mounted with their own lower surfaces nearly even with the ventral "boat-hull" shaped fuselage surface to provide the needed stability, while floatplane amphibians usually avoid the problem by dividing their buoyancy requirements between two floats, much like a catamaran.

Some non-amphibious seaplanes may be mistaken for amphibians (such as the Shin Meiwa PS-1) which carry their own beaching gear - usually this is a wheeled dolly or temporary set of wheels used to move a flying boat or floatplane from the water and allow it to be moved around on land but can also appear as a conventional undercarriage. These are not built to take the impact of the aircraft landing on them. An amphibian can leave the water without anyone getting in the water to attach beaching wheels (or even having to have any handy), yet a fully functional undercarriage is heavy and impacts the aircraft's performance, and isn't required in all cases, so an aircraft may be designed to carry its own.

Hazards

An occasional problem with amphibians is with ensuring the wheels are in the correct position for landing. In normal operation, the pilot uses a checklist, verifying each item. Since amphibians can land with them up or down though, the pilot must take extra care to ensure they are correct for the chosen landing place. Landing wheels up on land may damage the keel (unless done on wet grass, a technique occasionally used by pilots of pure flying boats), while landing wheels down on water will almost always flip the aircraft upside down, causing substantial damage.

Vickers Viking amphi
Vickers Viking - an early amphibian.

Usage

Amphibious aircraft are heavier and slower, more complex and more expensive to purchase and operate than comparable landplanes but are also more versatile. Even if they cannot hover or land vertically, for some jobs they compete favorably with helicopters and do so at a significantly lower cost. Amphibious aircraft can be much faster and have longer range than comparable helicopters, and can achieve nearly the range of land based aircraft,[1] as an airplane's wing is more efficient than a helicopter's lifting rotor. This makes an amphibious aircraft, such as the Grumman Albatross and the Shin Meiwa US-2, useful for long-range air-sea rescue tasks. In addition, amphibious aircraft are particularly useful as "Bushplanes" engaging in light transport in remote areas, where they are required to operate not only from airstrips, but also from lakes and rivers.

History

In the United Kingdom, traditionally a maritime nation, a large number of amphibians were built between the wars, starting from 1918 with the Vickers Viking and the early 1920s Supermarine Seagull and were used for exploration and military duties including search and rescue, artillery spotting and anti-submarine patrol. The most notable being the Short Sunderland which carried out many anti-submarine patrols over the North Atlantic on sorties of 8 – 12 hours duration. These evolved throughout the interwar period to ultimately culminate in the post World War 2 Supermarine Seagull, which was to have replaced the wartime Walrus and the Sea Otter but was overtaken by advances in helicopters.

Sikorsky S-38B 2
replica of Osa's Ark - a Sikorsky S-38 used to explore Africa in the 1930s.

Starting in the mid-1920s and running into the late 1930s in the United States, Sikorsky produced an extensive family of amphibians (the S-34, S-36, S-38, S-39, S-41, S-43) that were widely used for exploration and as airliners around the globe, helping pioneer many overseas air routes where the larger flying boats could not go, and helping to popularize amphibians in the US. The Grumman Corporation, late-comers to the game, introduced a pair of light utility amphibious aircraft - the Goose and the Widgeon during the late 1930s for the civilian market. However, their military potential could not be ignored, and many were ordered by the US Armed forces and their allies during World War II. Not coincidentally, the Consolidated Catalina (named for Santa Catalina Island off the coast of southern California whose resort was partially popularized by the use of amphibians in the 1930s, including Sikorskys, and Douglas Dolphins) was redeveloped from being a pure flying boat into an amphibian during the war. After the war, the United States military ordered hundreds of the Grumman Albatross and its variants for a variety of roles, though, like the pure flying boat was made obsolete by helicopters which could operate in sea conditions far beyond what the best seaplane could manage.

PiaggioP136L1Takeoff
Italian Air Force Piaggio P.136 during takeoff retracting the wheels that make it an amphibian.

Development of amphibians was not limited to the United Kingdom and the United States but few designs saw more than limited service - there being a widespread preference for pure flying boats and floatplanes due to the weight penalty the undercarriage imposed, yet Russia also developed a number of important flying boats, including the widely used pre-war Shavrov Sh-2 utility flying boat, and postwar the Beriev Be-12 anti-submarine and maritime patrol amphibian. Development of amphibians continues in Russia with the jet engined Beriev Be-200. Italy, bordering the Mediterranean and Adriatic has had a long history of waterborne aircraft going back to the first Italian aircraft to fly. While most were not amphibians, quite a few were, including the Savoia-Marchetti S.56A and the Piaggio P.136.

Amphibious aircraft were particularly useful in the unforgiving terrain of Alaska and northern Canada, where many remain in civilian service, providing remote communities with vital links to the outside world. The Canadian Vickers Vedette was developed for forestry patrol in remote areas, previously a job that was done by canoe and took weeks could be accomplished in hours, revolutionizing forestry conservation. Although successful, flying boat amphibians like it ultimately proved less versatile than floatplane amphibians and are no longer as common as they once were. Amphibious floats that could be attached to any aircraft were developed, turning any aircraft into an amphibian, and these continue to be essential for getting into the more remote locations during the summer months when the only open areas are the waterways.

US-2 9903-2
ShinMaywa US-2, developed in the 2000s in Japan from the older Shin Meiwa US-1A

Despite the gains of amphibious floats, small flying boat amphibians continued to be developed into the 1960s, with the Republic Seabee and Lake LA-4 series proving popular, though neither was a commercial success due to factors beyond their makers control. Many today are homebuilts, by necessity as the demand is too small to justify the costs of development, with the Volmer Sportsman being a popular choice amongst the many offerings.

With the increased availability of airstrips in remote communities, fewer amphibious aircraft are manufactured today than in the past, although a handful of amphibious aircraft are still produced, such as the Bombardier 415, ICON A5, and the amphibious-float equipped version of the Cessna Caravan.

Development of amphibians has continued into the new millennium. The ShinMaywa US-2 was developed in the 2000s in Japan for the Japan Maritime Self-Defense Force.

See also

References

  1. ^ "Grumman Mallard". Archived from the original on 2007-09-28. Retrieved 2018-10-16.
Arado Ar 233

The Arado Ar 233 was a 1940s German design for a civil twin-engined amphibian flying boat, developed by Dewoitine in France under the control of Arado Flugzeugwerke.

Avro 501

The Avro Type H, Type 501, and Type 503 were a family of early British military seaplanes. They were a development of the Avro 500 design and were originally conceived of as amphibious, the prototype being fitted with a single large main float (equipped with wheels) under the fuselage, and two outrigger floats under the wings. Tests were conducted on Windermere in January 1913. It was later converted to a twin-float configuration and bought by the British Admiralty. It now, however, proved too heavy and was converted again – this time to a landplane.

An improved version, designated the 503 was demonstrated to the Inspector of Naval Aircraft, who placed an order for three machines. The prototype itself was demonstrated for the Imperial German Navy in its seaplane trials in June 1913 and was purchased by the government of the German Empire for evaluation purposes. This machine subsequently became the first aircraft to fly across the North Sea, from Wilhelmshaven to Heligoland, in September 1913. Gotha purchased a licence from Avro and produced the type as the WD.1 (Wasser Doppeldecker – "Water Biplane"). Unlicensed copies were also built by Albatros, AGO, Friedrichshafen. Some WD.1s were provided to the Ottoman Empire following their withdrawal from German navy service.

Columbia XJL

The Columbia XJL is a large single-engined amphibious aircraft designed by Grumman Aircraft but built by the Columbia Aircraft Corp. It was intended to replace the Grumman J2F Duck but the type did not reach production status.

Curtiss-Wright CA-1

The Curtiss CA-1 (sometimes known as the Commuter or the Courtney Amphibian) was an American five-seat biplane amphibian designed by Frank Courtney and built by Curtiss-Wright at St Louis, Missouri.

Curtiss-Wright CW-3 Duckling

The Curtiss-Wright CW-3 Duckling (sometimes called the Teal) was an American two-seat amphibian flying-boat developed by Curtiss-Wright from the CW-1 Junior.

Curtiss Teal

The Curtiss Model 57 Teal was an American monoplane amphibian designed and built by the Curtiss Aeroplane and Motor Company. Two versions were built, a three-seater and four-seater but only one of each was built.The Teal was a monoplane amphibian with the pusher engine pod-mounted above the wing center section. It was designed for the private user, but due to the economic pressures of 1930s America only one three-seater (Teal A-1 registered N969V ) and one four-seater (Teal B-1 registered N970V) were built.

Dornier Do 12

The Dornier Do 12 Libelle III ("Dragonfly III") was the third of a line of small German flying boats of the 1930s. It started with the Dornier A Libelle I and the Dornier A Libelle II, though the Do 12 was not a continuation, but an entirely new aircraft.

The aircraft was amphibious and would carry three to four passengers. It was powered by a single Argus As 10 engine initially, then a Gnome-Rhône 5Ke Titan engine, mounted above the wing. It first flew in 1932 and went on to be used by the DFS to tow gliders.

Dornier Do 212

The Dornier Do 212 was a four-seat experimental amphibian flying boat built by the Swiss subsidiary of Dornier, in Altenrhein on Lake Constance. Design was initiated in 1938 by the German and Swiss branches, the latter being responsible for the actual construction of the prototype.

The Do 212 was an all-metal cantilever monoplane with fixed wingtip floats and a 343 kW (460 hp) Hirth HM 512-B-0 12-cylinder air-cooled engine which, mounted aft of the cabin, was buried in the fuselage and drove a four-blade airscrew aft of the tail by means of a shaft which could be tilted upward 12° to provide water clearance.

Initial water taxiing trials resulted in the enlarging of the wingtip floats. On 3 August 1942, a few attempts to take off from water were made, but these failed. A Do 24 was used to tow the Do 212 and it finally flew; however, instability forced the pilot to ditch just after takeoff. Further trials ended the same way. Difficulties were also experienced with the extension shaft, and the cooling of the engine presented a problem. Consequently, no further testing was undertaken, and the prototype was scrapped in 1943.

Douglas YOA-5

The Douglas YOA-5 was an Amphibious aircraft designed for the United States Army Air Corps. Although a prototype was built, it did not enter production.

Fairchild FB-3

The Fairchild FB-3 (Flying Boat number 3) was an all-metal flying boat developed by the new Fairchild Metal Boat Division of the Fairchild Aircraft Corporation. The aircraft did not go into production.

Floatplane

A floatplane (float plane or pontoon plane) is a type of seaplane, with one or more slender pontoons (known as "floats") mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, making the vehicle an amphibious aircraft. British usage is to call "floatplanes" "seaplanes" rather than use the term "seaplane" to refer to both floatplanes and flying boats.

Grumman G-65 Tadpole

The Grumman G-65 Tadpole was an American prototype light amphibian designed and built by Grumman. Only one was built and it did not enter production. It was later developed into a family of amphibious aircraft by David Thurston.

Hopfner HA-11/33

The Hopfner HA-11/33 was an amphibious flying boat built in Austria in 1933 to a specification by the Dr. Oetker company. The result was a conventional, high-wing cantilever monoplane with a stepped flying boat hull and pontoons on struts under the wings at mid-span. The cabin was fully enclosed, and the twin engines were mounted tractor-fashion on struts above the wing.

List of seaplanes and amphibious aircraft

The following is a list of seaplanes and amphibious aircraft, which includes floatplanes and flying boats, by country of origin.

Seaplanes are any aircraft that has the capability of landing on water while amphibious aircraft are equipped with wheels to alight on land, as well as being able to land on the water. Flying boats rely on the fuselage or hull for buoyancy, while floatplanes rely on external pontoons or floats. Some experimental aircraft used specially designed skis to skim across the water but did not always have a corresponding ability to float.

This list does not include ekranoplans, 'Wing-In-Ground-effect' (WIG), water-skimmers, wingships or similar vehicles reliant on ground effect.

Sikorsky RS

The Sikorsky RS was a designation used by the United States Navy for a number of different Sikorsky twin-engined amphibious flying boats.

Sikorsky S-43

The Sikorsky S-43 Baby Clipper was a twin-engine amphibious aircraft manufactured in United States during the 1930s by the American firm Sikorsky Aircraft.

Stroukoff YC-134

The Stroukoff YC-134, designed in 1956, was based heavily on the Fairchild C-123 Provider, itself designed by Michael Stroukoff. The United States military contracted with Stroukoff Aircraft Corporation to develop an improved version of the aircraft, combining features that the company had developed for the YC-123D and YC-123E.

Vickers Viking

The Vickers Viking was a British single-engine amphibious aircraft designed for military use shortly after World War I. Later versions of the aircraft were known as the Vickers Vulture and Vickers Vanellus.

Weserflug We 271

The Weserflug We 271 was a German flying boat active during World War II.

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