(Mu, Zeng Fengyun, Sun)
Use aircraft to carry personnel and equipment, and cooperate with other related technologies to extinguish or control forest fires. The contents include parachuting in forest areas, aerial spraying and aerial fire fighting.
19 19 The United States first tried to extinguish the fire by aerial spraying with military aircraft eliminated in World War I; Parachute fire fighting starts from 1939, from 1940 to 12 to 380 of 1979; 1946 helicopters are used for forest fire prevention. Up to 1976, there are more than 300 small and medium-sized helicopters. 1954, the United States successfully used a modified military torpedo plane to spray fire. After 1960, the United States and Canada concentrated on a lot of research on aerial spraying technology. 1967, Canada developed CL-2 15 amphibious forest fire fighting special aircraft. The load capacity of spraying aircraft has been from several hundred kilograms to several tons; Models range from fixed-wing aircraft to heavy-duty helicopters; There are one or more tanks in the machine. 1934 ~ 1935, the Soviet union successfully carried out parachute fire fighting experiments in forest areas, 1936 formally established parachute fire fighting teams, and by 1975, there were 2,400 parachute firefighters. 1956 used helicopters; In 1960s, An -2 aircraft was converted into An -2 п sprayer, and the spraying device of Ka -26 helicopter was tried. Our country began to organize parachute jumping fire-fighting test in forest areas in 196 1 year. In spring of 1963, parachute jumping was carried out for the first time at Daheishan fire site in Inner Mongolia. In 1965, Zhi -5 helicopter was used for forest fire prevention, and "aviation chemical fire-fighting technology" passed the national appraisal in 1976. The modified Yun -5 aircraft is used to carry "704" and "75" fire extinguishing agents for aerial spraying to put out forest fires. 1978, Heilongjiang province set up the first professional aerial fire fighting team in Daxinganling, and by the spring of 1982, the national aerial fire fighting team had grown to more than 1000. In addition, France, Spain, Italy, Australia, Japan, Mongolia and other countries have carried out aviation fire fighting to varying degrees.
Parachute fire fighting in forest area
Specially trained fire fighters are parachuted into remote forest areas with inconvenient transportation and sparsely populated areas by plane to complete the work of extinguishing forest fires or other tasks related to forest protection and fire prevention. Skydiving needs to know the fire and choose the landing place. The landing zone should not be less than150x150m. Use open spaces in forests, fields, grasslands, dry swamps, low shrubs and young coniferous forests. It is forbidden to use logging sites, burning sites, fallen trees, dead trees and places with high-voltage lines nearby as landing sites. When carefully observing the landing site, the plane descended to the height of 100 meters. After that, the plane rose to a height of more than 400 meters and parachuted the firefighters to the selected landing site. There are three ways of skydiving: ① Visual observation: If the landing site is large (1× 1 km) and the wind speed is low, this way can be adopted. When opening an umbrella, it enters against the wind, and the airspeed is 130km/h② Calculation method of wind force in flight: measure the drift angle with a sight, then obtain the wind speed and direction with an anemometer, a pilot's slide rule or a graphic method, and then calculate the opening time with the following formula:
Where t is the parachute release time (seconds); H is the flying height when the wind speed is determined (m); V is the descending speed of the parachutist (5m/s); W is the ground speed (km/h); U is the wind speed (km/h); V is the airspeed (km/h). (3) According to the parachute landing test method, that is, before the paratroopers parachuted, try to land a scaled-down parachute, and determine the entry course and parachute landing time of the aircraft when the parachute landed in the air according to the landing location and the distance from the center (landing point).
After the paratroopers landed safely, they dropped other articles and tools. Skydiving firefighters can use backpack sprayers, rope explosives, igniters and other small fire-fighting tools (see fire-fighting equipment) to put out the fire directly, or they can set up isolation belts and wear fire on them (see extinguishing forest fires). In addition to random patrols, parachutists can also do the following tasks: parachuting to residential areas or fire sites, organizing and guiding the masses to put out fires; Assist the fire commander to formulate the fire fighting plan; Open a helicopter landing site; Fire cleaning after aviation chemical fire extinguishing; Parachute rescue in emergency, etc. Skydiving firefighters should not stay in the fire for a long time, but should hand over the fire to ground support personnel. Notify observers by radio or signal when leaving the fire. If working in a distant fire, the observers will inform the nearby residential areas, units or fire departments after airdropping, and assist the paratroopers to return to the nearby residential areas or take them back by helicopter. The limitations of skydiving fire fighting are that personnel need special training, the technical level is high, there are many objective conditions (such as choosing landing sites and certain meteorological conditions), and the equipment is complex. The advantage is that you can patrol randomly and find that small fires can be put out immediately.
Aircraft descending to extinguish fire
Use helicopters to transport firefighters with relevant equipment to the forest area to complete fire fighting or other fire prevention tasks. In sparsely populated forest areas with extremely inconvenient traffic, airborne fire fighting should be adopted. After the fire broke out in these forest areas, the general ground fire fighting force could not be put out in time, and it was difficult for paratroopers to return from the fire because of the lack of parachute landing sites. The airborne fire terminal should be located in the forest area. In order to expand the service area of aerial fire fighting, the temporary landing point and refueling point of helicopters should be selected in forest areas and evenly distributed in places with serious fire risks. When choosing a temporary landing site, avoid high-voltage lines, buildings and residential areas. If the selected site needs to be used many times, it should also be close to the highway to facilitate helicopter maintenance and logistics supply. The aerial fire fighting team may be composed of professionals and locals temporarily. They should be stationed in temporary stations or temporary landing sites near heliports and forest areas with serious fire risks. It is best to cooperate with small patrol aircraft in the terminal building where airborne fire fighting teams are used. Helicopters and air fire-fighting teams are on standby at the airport, and patrol aircraft patrol the air. When the patrol aircraft finds a fire during patrol, it will immediately inform the terminal of the fire location, area, type, fire extinguishing scheme and other related information through radio communication. According to the above situation, the wharf determines the fuel quantity and the number of people to transport fire fighting. The helicopter flew to the fire with airborne firefighters and tools, and strived to transport all the firefighters needed to the fire-fighting area before sunset. General fire fighters are transported to the rear of the fire and can be put into fire fighting after disembarking. Secondly, it was transported to the second wing of the fire. When the wind speed is low and the fire of the fire head is not strong, it can also be directly transported to the fire head to put out the fire, or when the wind speed is low and the fire is weak, the firefighters can be airlifted to a safe area in front of the fire head to put out the fire. The closer the helicopter landing point is to the fire line, the better, but it depends on the site conditions, fire, wind direction, wind speed and aircraft safety. If you can't land after reaching the fire, you can use the method of cable landing. After landing, firefighters can cut down trees and set up temporary landing sites for helicopters if necessary. If fires and fires have been discovered many times before, and meteorological conditions continue to be conducive to the occurrence of forest fires, helicopters can directly take firefighters for patrol flights. The basic fire fighting method of the airborne fire fighting team is to open the gap from a certain point of the fire line, and then divide it into two roads, each of which advances in different directions along the fire line, and cleans it while flapping to avoid re-ignition. After meeting with the adjacent fire brigade, it will be cleaned again (see fire fighting methods and fire fighting equipment). Because the helicopter can take off and land vertically and fly in the air in a small range, people and goods can be loaded and unloaded through rope ladders, cable drops, toothed discs or buckets, so the helicopter has greater flexibility and maneuverability. But it also has some limitations, mainly: the flight cost is expensive; The carrying capacity is greatly influenced by altitude and temperature; The structure and operation are complicated.
Air spray fire extinguishing
For aircraft with spraying device, water or chemical fire extinguishing liquid is poured on the fire line to directly extinguish the fire or set up isolation belt. The spraying device of the sprayer is composed of water tank (water storage tank), dosing equipment, spraying system (sprinkler and gate), water level indicator and ventilation pipeline, among which the performance of water tank and gate system is the main factor to determine the spraying effect. In the United States, many water tanks and sluice systems are developed and controlled by electronic computers. For example, the newly developed MFFS aerial spraying system (easy to disassemble without changing the aircraft structure) has been applied to many kinds of aircraft. In Yun -5 spray plane modified by China, the water tank is conical, the capacity is 1 ton, the diameter of spray nozzle under the fuselage is 22 cm, and the dump door weighs 17 kg. Good air tightness, quick door opening, emptying 1 ton of liquid medicine in 3 ~ 4 seconds. The spraying device of helicopter mostly adopts external bucket, which can be folded and fixed. When choosing a spraying plane, we should consider: ① the technical characteristics of the plane (model, speed, quantity and total capacity of fire fighting water tanks); 2 expenses; (3) the distance from the fire site to the fire extinguishing liquid storage base; (4) fire area; ⑤ Forest topography, water source and forest vegetation.
After the spraying plane flies to the fire area, the pilot should consider: ① choosing favorable terrain; (2) seize the favorable opportunity of meteorological conditions (small wind and stable airflow); (3) Give priority to small area spraying or rapid spraying. In the early stage of small fire, direct fire extinguishing is adopted, and indirect fire extinguishing (setting isolation zone) is sprayed in front of moving fire heads or surrounded by other fire lines. The relationship between the length and width of the ground medicine belt and the dosage per unit area is determined by the type, quantity and fire intensity of local combustible materials. When the speed of Yun -5 modified in China is 160km/h, the altitude is not more than 30 meters, and the wind speed is not more than 6-8 meters/second, the liquid medicine can be sprayed into a width of 1 0-12 meters, and the length is about 200 meters, and the liquid volume per unit area can be received. The external bucket used in helicopter can not only be used to douse the fire line, but also transport water, various articles and fire fighting equipment to the fire site. Only by closely cooperating with the fire fighting power on the ground can aerial spraying achieve good results.
The future development trend of aviation fire fighting is: ① adhere to the principle of comprehensive utilization, spray fire fighting is mainly used to control the fire head and spread, skydiving and airborne fire fighting are mainly used to put out small fires and clean up fire sites; (2) Develop small and multipurpose fire fighting equipment, suitable living equipment and safety clothing; (3) Multi-engine large and medium-sized aircraft will be more and more used for aerial spraying fire fighting, spraying devices will develop in the direction of standardization, and airport ground filling equipment will be improved and matched; (4) Quantitatively study the factors affecting the ground coverage model of spraying agent, and get the best spraying operation method and the most suitable flame retardant coverage; ⑤ Focus on air fire fighting, increase the number of helicopters, reduce the cost of flying hours, add helicopter gas stations and increase the radius of helicopter activities; ⑥ Develop professional aviation fire fighting teams and station in aviation forest protection stations and key temporary stations according to the fire.