Seaplane, Part V
An amphibious aircraft or amphibian is an aircraft that can take off and land on either land or water. All Amphibian aircraft are thus classified both as seaplanes and make up the rarest subclass of seaplanes. Like all seaplanes, Amphibious aircraft are typically flying boats and floatplanes — but while their major physical attributes are those placing them within those broad classes, amphibians are also engineered with retractable wheels making them amphibious — at the expense of extra weight and complexity, plus diminished range and fuel economy factors comparative to planes specialized for land or water only.
While floatplanes sometimes have floats that are interchangeable with wheeled landing gear (thereby producing a conventional land-based aircraft), it is rare for a floatplane to successfully incorporate retractable wheels whilst retaining its floats; the Grumman J2F Duck would be a notable example of one exception which does. Some amphibian floatplanes, such as the amphibian version of the Cessna Caravan, incorporate retractable wheels within their floats.
The majority of 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 J2F Duck), require small outrigger floats to be fitted underneath the wings: while these impose additional drag and weight on all seaplanes of this type, amphibious aircraft also face the possibility that these floats would hit the runway during wheeled landings.
A solution would be to have the aircraft fitted with wing-mounted retractable floats such as those found on the Grumman Mallard, a flying boat type of seaplane designed and built in the mid 1940s with dozens still employed today in regular small volume commercial (ferry service) air taxi roles.
The class which has retractable floats which also act as extra fuel tanks since fuel liquids weigh less than water of equal volume; these floats are removable for extended land/snow operations if and when use of extra fuel tanks is undesired but the plane type and class serves as an example of a true amphibious aircraft since they also retract up off the ground.
Amphibious aircraft are heavier and slower, more complex and more expensive to purchase and operate than comparable landplanes but are also more versatile.
They do compete favorably, however, with helicopters that compete for the same types of jobs, if not quite as versatile.
Amphibious aircraft have longer range than comparable helicopters, and can indeed achieve nearly the range of land-only airplanes, 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 ShinMaywa US-1, ideal for long-range air-sea rescue tasks. In addition, amphibious aircraft are particularly useful as “bush” aircraft engaging in light transport in remote areas, where they are required to operate not only from airstrips, but also from lakes and rivers.
Amphibious aircraft have been built in various nations since the early 1920s, but it was not until World War II that saw their widespread service.
The Grumman Corporation, a United States-based pioneer of amphibious aircraft, introduced a family of light utility amphibious aircraft – the Goose, the Widgeon and the Mallard – during the 1930s and the 1940s, originally intended for civilian market. However, the military potential of these very capable aircraft could not be ignored, and large numbers of these versatile aircraft were ordered by the Military of the United States and their allies during World War II, for service in air-sea rescue, anti-submarine patrol, and a host of other tasks. The concept of military amphibious aircraft was so successful that the PBY Catalina, which began life as a pure flying boat, introduced an amphibian variant during the war.
In the United Kingdom, Supermarine Aircraft produced the Walrus and the Sea Otter single-engined biplane amphibians which were widely used for observation and air-sea rescue duties before and during World War Two.
After the war, the United States military ordered hundreds of the HU-16 Albatross and its variants for use in open ocean rescue, for the United States Air Force, Coast Guard and Navy.
The capabilities of these amphibious aircraft were found to be particularly useful in the unforgiving terrains of Alaska and northern Canada, where some remained in civilian service long after the war, providing remote communities in these regions with vital links to the outside world.
Nonetheless, with the increased availability of airstrips and amenities in remote communities, fewer amphibious aircraft are manufactured today than in the past, although a handful of manufacturers around the world still produce amphibious aircraft (flying boats or floatplanes with retractable landing gear), such as the Bombardier 415, the Grumman Albatross and the amphibian version of the Cessna Caravan.
The largest amphibious aircraft currently in service is the Beriev A-40 of the Russian Navy, with a wingspan of 41.62 meter and a takeoff weight of 86 metric tons. The Beriev Be-200 is a smaller model for civil applications and had its first flight in 2004. It can carry 72 passengers and is also built in a version for fire fight. wild horse island flathead lake