The development of Chinese hovercraft. Since the late 1950s, China has begun research on the application of air-cushion technology and the development of hovercrafts. Over the past 40 years, in terms of air-cushion technology, through principle research, model testing, intermediate tests and trials, the technology of fully-cushioned and side-wall air-cushion vehicles has been basically mastered, and has entered the stage of development and application of practical models. The development and application of air cushion technology has adapted to the special needs of the military and civilians, creating conditions for ships to navigate and land in specific environments (such as shallow water rapids, dangerous shoals in the upper reaches of rivers, shallow beaches, and ice and snow areas). In the late 1950s, in order to explore new air cushion technologies, more than 40 units across the country organized efforts to begin principle research and model testing, and then trial-produced manned test vehicles and test boats. Some units use aircraft engines as power and adopt air propeller propulsion or jet propulsion; some units develop hovercrafts that can also be used for landing; others develop experimental ground effectors mainly for land use, called "drifting cars", "Wheelless cars", "Hovercraft" and so on. Although the names are different, they are essentially full-cushion lifting air cushion models. At that time, these test boats were not equipped with aprons and had poor maneuverability. Many problems were found in both sea and land tests, and they were only in the stage of theoretical application research. In 1960, Zhang Aiping, deputy director of the National Defense Science and Technology Commission, chaired a national air-cushion technology conference. After on-site exhibitions and comparisons of various types of test vehicles and test boats, it was clear that ships would be the main research direction, and decided to shorten the front, relatively concentrate efforts, and gradually develop key technologies. Problem organizations collaborated to tackle key problems, which has since changed the previous situation of “flowering everywhere”. After 1961, the country was in a period of adjustment, with a shortage of scientific research funds and difficulties in material supply. Many units stopped researching air cushion technology one after another, resulting in ups and downs.
In 1962, the Shipbuilding Professional Group of the State Science and Technology Commission organized the formulation of a ten-year plan for the development of ship science and technology (1963 to 1972), and included the development of air cushion technology in the planning project. The National Defense Science and Technology Commission determined that the Seventh Academy will take the lead and continue to organize research work. From 1963 to 1967, Shenyang Songling Machinery Factory in Northeast China successively developed fully-cushioned air-cushion test boats "Songling 1", "Songling 2" and "Songling 3" using aviation piston engines. Initially, a single-layer perimeter apron was used, and then a perimeter jet ham-shaped flexible apron was used. Trial trials were conducted in the Songhua River, Lushun offshore and Liaohe River water network areas. Shanghai 708 Research Institute specially organized forces and established a research institution. In the five years after 1963, it successively trial-produced small fully-cushioned air-cushion test boats No. 711-1 and No. 711-2 with a total weight of 4 tons at the Hudong Shipyard. . At first, only hard peripheral jets were used, and then ham-shaped flexible aprons were added. Finally, the capsule finger-shaped apron was used on the No. 71l-2 boat. After completion, they were repeatedly tested in Dianshan Lake and Huangpu River in Shanghai to study the basics of hovercraft navigation. Performance concerns include issues such as lift, propulsion, nose dive, overturning, stability and side drift. The rear of the No. 711-2 boat has been improved to use a controllable-pitch air propeller with variable positive and negative pitch. The electromechanical system control and driving of the entire boat are centralized controlled by one person. In addition, the apron lifting is linked with the rudder, which significantly reduces the turning radius of the boat. Small, the maneuverability is greatly improved, and it has the ability to smoothly enter river branches, go ashore and retreat to the beach, and cross ditches. The lake trial speed once reached 98 kilometers/hour. In 1967, during the trial voyage on the Jinsha River section in Sichuan and the Lancang River in Xishuangbanna, Yunnan, it successfully washed upstream in the rapid beach current. After returning to Shanghai, the boat was improved and sailed along the Huangpu River and Yangtze River estuary to the coast of Zhoushan for seakeeping tests. During this period, in order to explore the technology of adding water-entry rigid structures on both sides of the hull to form side walls to facilitate water propeller propulsion, the 708 Research Institute designed and trial-produced the side-wall air cushion test boat No. 711-3 in 1966. After conducting navigation tests on the Huangpu River, a series of intermediate tests were conducted on the Jinsha River, Lancang River, Zhoushan and other places, successfully crossing rapids and swirling water (during this period, many tests such as transverse stability, nose and tail air seals, and the addition of hydrofoils were carried out ), achieved initial success. Through multiple tests of the above-mentioned types of intermediate test boats, China has begun to master the basic rules of applying air cushion technology to ships in practice, creating conditions for trials.
In the winter of 1965, Zhang Youxuan, deputy director of the State Science and Technology Commission, held a discussion on ship technology policy and decided to promote the development of domestic hovercraft and launch the development of trial boats with the goal of solving urgent tasks for the military and civilians. Since then, the country has fully cushioned trial boat type 2, side wall type test boat, and trial boat type 4, which have been gradually pushed from inland rivers to coastal in-depth trials.
The picture on the right is a picture of China’s “Daku”-class (722-2) air-cushion landing craft passing by the “934” landing ship during a landing exercise.
In the late 1960s, in order to meet the transportation needs between coastal islands, the General Logistics Department of the People's Liberation Army commissioned the 708 Research Institute to design a fully-cushioned air-cushion transportation trial boat Type 716. It was built by the Hudong Shipyard in 1978. The boat has a total weight of 16 tons and a designed load capacity of 2 tons. It was trialled in Dianshan Lake that year and its speed reached 100 kilometers per hour. Later, it was transferred to the Guangdong Sea Area for trial use. It was found that high-volatile gasoline used in aviation piston engines could easily cause accidents and was discontinued.
In 1975, the Navy planned to test air-cushion landing craft and commissioned the 708 Research Institute to design the 722 medium-sized fully-cushioned air-cushion landing test craft. With the strong assistance of metallurgy, machinery, aviation and other industrial departments and relevant factories in Tianjin, the boat was completed and commissioned in 1979. The boat has a total weight of 65 tons, is equipped with bow and stern doors, and can carry 1 baggage truck or 1 landing infantry reinforcement company. The load capacity is 15 tons. The hull is made of aluminum and is equipped with a decommissioned aviation gasoline piston engine 4 Taiwan, with a total power of 4×1100 kilowatts and a speed of 89.8 kilometers/hour. In 1980, the boat organized two long-range tests: the first round trip between Tanggu and Qinhuangdao, and the second time across the Bohai Bay and around the mountains to Qingdao. The two voyages totaled about 800 nautical miles. The test results show that the stability, lifting ability, maneuverability and speed of the boat are good, and the machine parts, shafting and aprons can operate normally with careful maintenance. However, the main engine has a high failure rate, loud noise and is difficult to withstand in the marine environment. The corrosion resistance is poor, especially the use of highly volatile gasoline as fuel does not meet the actual combat requirements and can only be used for intermediate testing. From 1981 to 1982, with the 708 Research Institute as the main body, the Navy and the 702 Research Institute worked closely together to organize two seakeeping and rapidity tests under Level 3 sea conditions in the waters of Qingdao and off Wusongkou in the East China Sea to conduct hull testing. Structural vibration, apron stress, strain and cabin noise tests provide first-hand sea experimental data for the development of practical models.
After the 1960s, domestic research on side-wall air cushion trial boats was very active. In the late 1960s, in order to meet the needs of rapid transportation passenger transportation on the Sichuan River and Jinsha River, the 713 side-wall hovercraft was designed by the 708 Research Institute and built by the Hudong Shipyard. It was handed over to Chongqing Steamship Company for trial use in 1971. The boat has an aluminum structure and is powered by the first batch of domestic trial-produced 12V135 supercharged high-speed diesel engines. It can carry more than 80 passengers. However, due to frequent host failures, difficulty in maintenance, and poor economic efficiency, it was not officially put into operation and remained idle after 1973. In 1977, the boat was modified and repaired, and together with other hovercrafts, it went on a long-distance trial in formation. It sailed from Chongqing to Yibin, then traced the Jinsha River to Xinshi Town, returned to Yibin, and then traced the Minjiang River to Leshan, and then returned to Chongqing. The whole journey was more than 1,500 times. Kilometers, it has withstood the test of rapids, steep walls, shoals, large whirlpools and sharp turns.
In 1967, the General Logistics Department of the People's Liberation Army commissioned the 708 Research Institute to design and Qiuxin Shipyard to build the 717 type water-jet propelled side-wall hovercraft for shallow water rapids sections. The boat was built in 1973, with a total weight of 12 tons and a load capacity of 2 tons. It uses a domestic 12V150ZC diesel engine as the main engine with a power of 220 kilowatts and a speed of only 42.8 kilometers/hour, which does not meet the design requirements. The boat was decommissioned after 1975 and was transferred back to the 708 Research Institute for improvement. After the improvement, it was named Type 717-A. It has good maneuverability, is convenient for docking and leaving the dock, has a speed of 48.5 kilometers per hour in the river, and can travel in crowded waterways. .
Since the 1970s, the Shanghai Shipping Research Institute has been committed to the development of air-cushion passenger boats that use fiberglass hull structures and are suitable for use in water network areas. In view of the characteristics of inland rivers such as shallow water, many bays, many ships, and the speed should not be too fast, a 5-ton all-glass fiber reinforced plastic side wall test boat with double fan linkage was developed, and the trial was successful in 1975.
In 1970, the 708 Research Institute designed the 719 coastal side-wall air-cushion test boat with a steel hull and a fiberglass superstructure. The main engine used three 12V180Z high-speed diesel engines, each with a power of 880 kilowatts. Due to the impact of ten years of unrest, the completion of the boat was delayed until 1978. The boat's speed was relatively low, only 64.8 kilometers per hour. It sailed 470 nautical miles from Fuzhou to Shanghai. Many tests were conducted along the way, and problems such as shafting vibration, apron tearing and mud accumulation in the tail seal were found.
In 1983, the boat was improved and named Type 719-1. The length of the boat was increased by 6.5 meters, the total weight was increased to 96 tons, the passenger capacity was increased to 180, the speed was 57 kilometers/hour, and the economy was improved. The construction of this type of boat was undertaken by Wuhu Shipyard. After completion, it was operated by Nanjing Tourism Company.
Through the large number of tests carried out on inland rivers and coastal areas by the above-mentioned various types of trial boats, we have basically mastered the lifting, propulsion, speed, stability and maneuverability of air cushion technology applied to ships. The laws of the problem were studied, and the seakeeping performance of hovercraft was studied from practice and theory, which laid the foundation for its practical application. In order to promote the early practical application of air cushion technology in the development of ships, in May 1980, the National Defense Industry Office of the State Council hosted the second national air cushion technology professional conference. The meeting believed that China's air cushion technology has stayed in the test and trial boat stage for a long time, mainly due to the lack of suitable power equipment systems and the incompatibility of the boat hull and flexible apron materials. In view of the limited funding for scientific research, it is necessary to start with the development of small hovercraft for inland rivers and gradually transition to the practical use of medium-sized boats for estuaries and coastal areas. In October 1982, the third professional conference on air cushion technology was held to examine and study the difficulties and problems that occurred in the transition to practical use, further unify thinking, strengthen leadership, and propose measures and methods to solve problems. Under the guidance of the reform and opening up policy, relevant departments introduced advanced foreign technology and equipment. After five years of efforts, the main key equipment and equipment have been basically solved, and the development of hovercraft has finally entered the practical stage.
(1) Side-wall water-jet propelled air-cushion passenger craft for inland rivers
In the early 1980s, the Shanghai Shipping Research Institute and the Anhui Water Transport Research Institute cooperated to design the WD401 inland side Wall-type water-jet propulsion hovercraft, built and produced in small batches by Chaohu Shipyard. The boat has a total weight of 16 tons, 40 passenger seats, a sailing draft of 0.45 meters, a speed of 32 kilometers per hour, and good economy.
In 1981, the 708 Research Institute modified the 717-A boat for the second time and named it the 717-C boat. It was later used as a prototype boat to design and build a passenger boat for Chongqing Steamship Company. The 54-passenger 717-2 type boat "Minjiang" designed and built a 70-passenger 717-3 type boat for Chongqing Ferry Company. The speed of the two boats is 46.9 kilometers/hour and 44 kilometers/hour respectively, and the cabin noise is about 75 decibels. After completion, they were both operated in Chongqing. They have been in service for several years since October 1984. Normally, the one-way trip from Chongqing to Luzhou costs 249,000 yuan. meters, the one-way distance to Yibin is 372 kilometers in summer and only takes 6 hours to 8 hours and 30 minutes, which greatly shortens the running time.
Type 716 fully-cushioned air-cushion traffic boat
(2) Side-wall air-cushion passenger boat for harbors and estuaries
In 1980, Tianjin commissioned the 708 study The side-wall air-cushion tourist boat "Jinxiang" for harbor use was designed and built by Dagu Shipyard. The boat is built of corrosion-resistant aluminum alloy. It uses two 12V150ZC high-speed diesel engines for propulsion and one 12V150ZC main engine for lifting, with a total power of 880 kilowatts. From 1983 to 1985, the boat was in trial operation on the Shanghai-Nantong line. The mechanical equipment was reliable, the apron life span was 600 hours, and all mechanical parts were normal. However, the seakeeping performance was poor when sailing in Level 3 sea conditions.
In 1985, the 708 Research Institute designed the 719-2 "Hongxiang" side-wall air-cushion ferry based on the 719-l prototype boat. It was trial-produced by China Shipyard and delivered in the winter of 1987. use. The ship has a total weight of 123.5 tons, uses three imported TBD234V16 high-speed diesel engines as the main engine, has a speed of 44-50 kilometers/hour, and carries 258 passengers. It is used for short-distance passenger transportation from Shanghai to Chongming, shortening the ferry time from the original two hours. to forty-five minutes. The actual ship operation shows that its performance is stable, its lift and propulsion power devices are reliable, and its apron life has adapted to the operational requirements. It is one of the practical ship types.
(3) Small fully-cushioned "air-cushion jeep"
In order to be used in swamps, tidal flats, mud and other areas that are difficult to reach by ordinary vehicles and ships, the Dagang Oilfield Headquarters commissioned 708 The institute has developed a small, fully-cushioned "air-cushion jeep" that can be carried by train. The boat is made of corrosion-resistant aluminum alloy and is equipped with two automobile gasoline engines with a power of 2×44 kilowatts. It adopts ducted propellers and capsule-type aprons. It has a total weight of 2.6 tons and can carry 8 passengers. After users use it, they can renew their subscription for 4 ships.
In order to reduce the main engine failure rate and blade flutter, the boat switched to an imported Deutz air-cooled high-speed diesel engine. This modified boat (Type 7201) is produced in small batches by Hangzhou Dongfeng Shipyard and Wuhu Shipyard. 17 boats have been built and delivered to users such as relevant military regions, the Ministry of People’s Armed Forces, the Yellow River Water Conservancy Commission, and Dagang Oilfield. In 1987, the Henan Provincial Tourism Bureau commissioned the 708 Research Institute to design and build the 7212 fully-cushioned hovercraft for Yellow River tourism. The ship was built in 1989 and named "Zhengzhou". It has a total weight of 10.3 tons and carries 33 passengers. It uses 3 Deutz BF6L913C air-cooled diesel engines (1 is used for lifting power and 2 are used for propulsion power). , in addition, it is equipped with 2 ducted air propellers, placed on the left and right sides of the tail. The ship is a practical hovercraft used to develop tourism resources in the Yellow River.
China's Type 724 air-cushion landing craft is conducting a landing exercise
(4) Coastal fully-cushioned air-cushion transportation craft and landing craft
In 1983, in response to military needs, The 708 Research Institute and the Hudong Shipyard are jointly responsible for modifying the 716 fully-cushioned air-cushion transportation boat. Its main engine was replaced with three imported Deutz high-speed air-cooled diesel engines with a total power of 950 kilowatts. The hull was appropriately lengthened, a ducted propeller was used, and the pad lift, propulsion system and apron were redesigned. From 1984 to 1985, after repeated debugging, sea trials, refurbishment and improvement of the shaft system and air propeller, all technical performances of the boat met practical requirements. In the summer of 1988, it sailed across the South China Sea Islands for training purposes.
In 1983, the 409-type gas turbine was successfully developed. Each unit has a power of 2,205 kilowatts and uses light diesel to meet practical requirements. Based on the 722 prototype boat and using the 409 machine power, the 708 Research Institute designed the coastal medium-sized full-cushion air-cushion landing craft 722-2. In order to extend the life of the apron and improve the sea-keeping performance, the boat switched to a low-resistance response apron; in order to improve the hull structure's resistance to seawater corrosion, a newly developed magnesium-aluminum alloy was used. The boat is equipped with two 409-type gas turbines, coaxial branch drive fans and ducted air propellers. When gas turbine power units are used in hovercraft, key technical issues need to be overcome, such as joint control of the engine and propellers, air intake filtration, exhaust injection, and low-working-condition navigation. To this end, after the single machine was successfully delivered in the no-load test on the test bench of the manufacturer, various onshore joint debugging and control tests were carried out to simulate the specific conditions of the hovercraft, as well as performance measurements such as variable working conditions and joint control of the machine and propellers. In 1986, various simulation tests on land of the power unit were successful, and it was shipped in 1987. In 1988, the Dagu Shipyard completed the air-cushion landing craft and began trial trials. In 1989, the sea and landing tests were successful, and it was delivered for use. This is an important sign that China's hovercraft technology has entered the practical stage.
(5) Application of air cushion technology in other aspects
New progress has been made in the application of air cushion technology in other aspects. In 1981, the 200-ton air-cushion segmented barge jointly designed by the Heilongjiang Provincial Water Transport Research Institute and the Shanghai Shipping Research Institute had a certain drag reduction effect when running at low speeds and played an energy-saving role. Another example is that the Shanghai Shipbuilding and Repairing Plant used a non-automatic air cushion platform in the early 1980s to transport the complete low-speed heavy-duty marine diesel engines manufactured by the plant to the dock barges. Another example is to transport heavy equipment required for oil exploration and extraction through tidal flats, swamps and humid areas. The 708 Research Institute designed a low-speed self-propelled air cushion platform with a total weight of 80 tons and a payload of 35 tons. It is equipped with two light 12V180 diesel engines. , each with a rated power of 660 kilowatts, was built by Hangzhou Dongfeng Shipyard in 1985 and handed over to Tianjin Dagang Oilfield for use.