An amphibious aircraft or amphibian is an aircraft that can take off and land on both land and water. Amphibious aircraft are heavier and slower, more complex and more expensive to purchase and operate than comparable landplanes but are also more versatile. The U.S. military designed AAV in order to deploy troops rapidly from an amphibious assault ship onto land.
Amphibious aircraft can be much faster and have longer range than comparable helicopters, and can achieve nearly the range of land based aircraft, 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.
China successfully tested its first domestically built amphibious aircraft ( AG 600, codenamed Kunlong ) with a series of water taxing and low-flight trials. Designed and built in China by the Aviation Industry Corporation of China (AVIC), the AG600 is reportedly set to be the largest amphibious aircraft in the world, roughly the size of a Boeing 737. When full operational , the AG600 would shift the balance of power in the disputed region with its ability to quickly transport troops and supplies, as well as provide other support, such as shifting garrisons in the south china sea. The aircraft can also be used to support foreign vessels for search and rescue missions.
In April 2020, China’s independently-developed AG600 large amphibious aircraft has conducted test flights over the sea, according to its developer Tuesday. It represents a major step forward before the amphibious airplane model conducts its first taking off from the sea surface, which is planned within the year, said the state-owned plan maker Aviation Industry Corporation of China (AVIC). Through the test flights, crew members confirmed and familiarize themselves with the airspace and marine environment for the upcoming test flight missions. AG600 conducted its maiden flight in December 2017 and completed its first takeoff and landing on the water in October 2018.
Chines companies and government departments have already placed 17 orders for the aircraft, which along with many other PLA projects, are designed to help China assert itself as an emerging maritime power. That’s especially the case in the contested South China Sea, where China has been fortifying remote outposts with military facilities including missile shelters, sensor arrays, and radar systems. Now China is expanding its presence and showing assertiveness in the islands of Indian Ocean from Sri Lankan Hambantota port to Pakistan’s Gwadar port.
Military roles including surveillance, interdiction of hostile ships, combat SAR, anti-shipping and anti-submarine warfare that are performed by larger amphibians but limited in scope with land-based aircraft plus land and ship-based helicopters having taken over most of these tasks. Some entities, most notably the Japanese Self Defense Forces, have still retained a significant capability especially in the SAR field with modern heavy platforms plus highly trained crews.
Indian military is also interested in large amphibious aircrafts for operations over island territories far from the mainland and with limited infrastructure. Smaller types can augment the capabilities of surface ships, helicopters and land or carrier-based fixed-wing aircraft. For long range SAR and Special Operations in a marine environment, the amphibian may be the only viable option in specific scenarios.
With Japan’s export policy being liberalised in recent years, allowing the country to export defence equipment, India is planning to import amphibious aircraft from Japan, said Rear Admiral Dinesh K Tripathi, Flag Officer Commanding, Eastern Fleet in Oct 2018. An amphibious aircraft can take off from both land and water and contenders like ShinMaywa US-2 of the Japanese navy can be used for rescue operations from air to sea.
Amphibians have the capability to operate both from water and land with suitable hulls and flotation devices for water operation and wheeled landing gear for land operation. However, some types have only restricted usage as far as the landing gear goes and these confine their land capabilities to being towed onto land for maintenance and parking. A true capability requires landing gear capable of supporting the aircraft for take-off and landing from runways up to maximum operating weights.
An amphibious aircraft can be fixed wing or rotary wing aircraft. Fixed-wing amphibious aircraft are seaplanes that are equipped with retractable wheels whereas, rotary wing aircraft is equipped with special bearpaws along with retractable wheels. Some amphibians are fitted with reinforced keels that act as skis, allowing them to land on snow or ice with their wheels up. These amphibious aircraft are used for commercial and military applications. They are best suited for offshore applications where the landing surface is not available and has to be made on 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. 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.
Search and Rescue. The peacetime scenarios will be conventional SAR for picking up survivors of ditched aircraft, occupants of surface vessels in distress or evacuation of injured personnel from ships as well as places where runway facilities do not exist. Combat rescue and recovery will involve retrieval of aircrew who have ejected and survivors of damaged/sunk ships, recovery of Special Forces teams and captured equipment.
Surveillance of Shipping. Conventional fixed and rotary wing aircraft carry out these roles but are again limited to operation in the air only and not on the water surface. After identification from the air, they can pass on information to base. After that they can either destroy or threaten the target but not physically occupy it without deploying personnel by parachute or, from a helicopter by lowering them onto the target area.
Interdiction. The obvious scenarios are anti-contraband, counter-terrorism, anti-infiltration and anti-piracy operations. Only surface vessels or submarines have the capability to perform these tasks and using the latter is a gross waste of scarce and at times, strategic assets. Speed of response is a constraint and unless surface forces happen to be in the vicinity, they cannot provide swift response.
Anti-Submarine Operations. Seaplanes and amphibians were very effective in this role in World War II. Although amphibians do not have the capability to hover like helicopters, an attribute that enables the latter to deploy sensors like dunking sonars, they can carry a wide variety of weapons and sensors. Their multi-role capabilities, faster sprint speeds and larger radii of action make them more versatile.
Logistics Support and Communications. Many maritime communities and bases are solely dependent on ships for supply and connectivity because terrain or space constraints inhibit construction of airfields. The Lakshadweep chain with small coral islands, has limited scope for runway construction. This applies to portions of the Nicobar Islands and terrain considerations create problems in the Andaman Islands group as well.
Amphibians are affected by weather conditions such as surface winds and visibility while landing or take-off on water in the same way as on land. In addition, an important factor is the state of the water surface. Wave heights (amplitude measured from crest to trough) and wave lengths (frequency measured from crest of one wave to the crest of the following/preceding wave) are the major factors. Both are, in turn, influenced by surface winds and sea currents and in waters closer to shore, by the sea-bed also. Waves speed up as the water becomes shallower and this reduces wave length while increasing wave heights. Open and deeper water is less influenced by the land and true open water conditions exist from 150 to 200 km from the coast. Modern amphibians can operate on high seas with wave heights of up to three metres provided wave lengths are above 80 metres. Such conditions generally exist in open waters except in adverse weather conditions. No other aerial platform has this capability.
Designing a seaplane aircraft must gather the knowledge of studying both aircraft and boat technology. The seaplane must meet the buoyancy requirements, have good water takeoff and landing characteristics, an acceptable hydrostatic stability, structural support for both water and air capability, and good aerodynamic characteristics that could affect flight performance.
The drawbacks of a traditional seaplane are:
- Higher aerodynamic cruise drag due to additional structures.
- Hydrodynamic drag while planning due to large wetted surface area.
- Stability issues resulting from limits on dimensions and weight of floating gears.
- Hindrance from water spray, requiring specially designed shapes to divert the spray away.
- Low performance in high waves and cross winds, making smooth cruising in rough weather difficult.
- Even maneuverability in water could be a deciding criterion, especially where narrow water strips pose a problem
The aircraft must possess transverse and longitudinal aerodynamic and hydrostatic stability at all speeds even in low speed operations in water. It must be designed for Short Take Off and landing operations (STOL). It should be possible to land the vehicle without excessive impact forces to airframe. Water tight hull or lower fuselage to protect passengers, freight and equipment bays.
The 37-meter-long AG600 with a wingspan of 38.8 meters, can take off and touch down on both land and water. It has a range of 2,800 miles and can be used on waves as high as six and a half feet. The amphibious plane can store and drop 12 tons of water and make some 30 rounds without refueling, which makes it ideal to battling wildfires.
The massive airplane with a maximum take-off weight of 53.5 tons, powered by four turboprop engines, the aircraft is capable of carrying 50 people and can stay airborne for 12 hours and can also be deployed in search and rescue operations over water. It is a turboprop airplane with four engines. With maximum take-off weight of 53.5 tons, it surpasses both Japan’s ShinMaywa, US-2 and Russia’s Beriev Be-200 amphibious planes.
“Its successful maiden flight makes China among the world’s few countries capable of developing a large amphibious aircraft,” the chief designer, Huang Lingcai, told Xinhua.
Russia Developing New ‘Sub-Killer’ Version of Be-200 Amphibious Aircraft
The Russian Navy has announced plans to order the purchase of an anti-submarine version of the Be-200 amphibious aircraft by 2020, to search for, detect and destroy [enemy] submarines, a high-ranking Navy official told the Russian news agency RIA Novosti.
He recalled that Russia’s naval aviation fleet currently includes obsolete 1960’s-era Beriev Be-12 turboprop-powered amphibious aircraft, the service life of which is already expiring. The plane was taken out of production a long time ago. Designed for firefighting, search and rescue, maritime patrol, and cargo as well as passenger transportation, the Be-200 can carry 12 metric tons of water, or up to 72 passengers
Japan’s Giant US-2 Amphibious Flying Boat
The ShinMaywa US-2, which is a direct outgrowth of the half-century-old US-1 design it replaced, provides search and rescue, maritime patrol, firefighting, medical evacuation, and logistical support capabilities for the Japan Maritime Self Defense Force. It was the largest amphibious flying boat in production up until China bested it with their AG600 amphibian that first flew in 2017. But that aircraft isn’t yet operationally deployed, the US-2 is, and it recently displayed its somewhat astonishing short-takeoff and landing (STOL) capabilities to onlookers at the Red Bull Air Races in Chiba.
It features a glass cockpit, a digital flight control system, and four Rolls-Royce AE 2100J turboprop engines that pump out 4,600hp each. In its firefighting configuration, she can deploy an impressive 15 tons of water. Performance-wise, the US-2 cruises along at 300mph at 20,000 feet and has a range just shy of 3,000 miles. It can also land in some really rough seas, with waves up to around nine feet tall. Yet what’s most impressive, as the videos above showcase, is the US-2’s short-takeoff and landing (STOL) capabilities that are made possible primarily by a blown flap and flight control system arrangement. This not only allows for very short and slow takeoffs and landings, but it also gives US-2 pilots a unique level of controllability even at very slow speeds.
India plans to buy from Japan and build indigenous
India Japan signed deal of buying of Japanese US-2i .The deal is even more important as China is readying its own amphibious aircraft AG600, stated to be the world’s largest. In April 2017, China successfully conducted maiden glide test of its first amphibious aircraft, in the southern Chinese city of Zhuhai. India Japan strategic partnership got a boost When Prime Minister Narendra Modi visited Japan in November 2016, and Japan and India concluded an agreement for cooperation in the peaceful use of nuclear energy like the civil nuclear agreement. Now India plans to buy dozen Japanese US-2i amphibious aircraft six each for the Navy and Coast Guard, worth Rs 10,000 crore. Powered by four big turbo-props, the US-2i is capable of short take-offs from land as well as water.
This proposed US-2i deal is intended to send a strong signal to an increasingly belligerent China in the Asia-Pacific region which is now asking India to stay away from Sri Lanka where it has purchased Hambantota port. While coast guard would utilize them for search and rescue operations, the US-2i shall also expand Indian Navy’s reach and power projection in Indian Ocean.The mammoth 47-tonne aircraft, carrying 18 tonnes of load, can take off from, or land on, a 300-metre stretch of water or land, its four giant engines needing just 7 seconds to get airborne.
The US-2 with operational range of 4,500 km and a cruise speed of 480 km/hr , it can patrol areas 1800 kilometers away. It shall be invaluable from surveillance of vast coast line of Andaman and Nicobar region to carrying out flood relief operations North-East. Its minimum cruise speed is approximately 90 km/hr making it valuable in search and rescue tasks.They can patrol the economic zone as well as rapidly transport 30 combat-ready soldiers to “hot zones” in an emergency, even in 10-foot waves.
India is also looking for indigenous route with India’s Hindustan Aeronautics Limited (HAL) has revealed its intention to venture into building amphibian aircraft. HAL-TAD Kanpur floated an RFI (Request For Information) seeking a partnership for design and development of such an aircraft. RFI invites information, from reputed design agencies or manufacturers only, for consultancy or to partner in design and development of an HAL built Do-228 aircraft to a Seaplane version.
HAL is also working on larger Conceptual design and development of Amphibious Aircraft which could rival China’s AVIC AG600 in the region in a long run. As per HAL, they are plans to develop 3 Configuration of this Amphibious Aircraft to meet different roles and requirements.
- Basic Configuration: To Carry out Long Range Search & Rescue, Utility missions, Transport missions, patrol aircraft and Troop transport missions.
- Civilian Configuration: To be used as a Civilian transporter to connect to islands and other regional countries. Can also be used as Civilian aircraft for regional connectivity since it will also be equipped with retractable landing gears.
- Military Configuration: To be used in Anti-Submarine Warfare roles, Anti-Surface unit Warfare, Anti-Piracy/Narcotics/People smuggling, Combat Search & Rescue, Special Forces support, General Maritime Surveillance and a wide range of maritime C4ISR and combat roles and missions.
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