Hundreds of thousands of square kilometers of forest land are burned out on our planet every year. Forest fires cause enormous damage. In addition to harm to the environment, industrial wood, animals, and often people die in the fire. In order to timely detect fires and prevent the spread of fire over vast territories, special aviation fire-fighting services have been created in many countries. Since woodlands often occupy a large area, firefighting aircraft have been used for operational fire detection and localization for many decades. It is responsible for the widest range of tasks - from detecting a fire source and transmitting information about it to ground services to the complete elimination of a forest fire.
The first attempts to combat the fire element from the air were recorded in the United States and Canada at the end of the 20s of the last century. However, due to the small carrying capacity, fragile biplanes of those years could take on the strength of several hundred liters of water, and their effectiveness in this field turned out to be low. The idea itself was recognized as promising, but there was no aircraft suitable for its implementation at that time. Much more benefit was then from the transfer of fire brigades, water motor pumps, fuel and equipment to forest airfields.
Much has changed since the end of World War II, when there was a huge surplus of decommissioned military aircraft, which are still in very good condition, and demobilized qualified pilots. However, it took the American authorities some time to realize the possibility of transferring converted combat aircraft to private hands and firefighting services. Therefore, training biplanes Stearman RT-17 were initially used for fire-fighting purposes. In the 1930s and 1940s, the RT-17 was the "training desk" for the US Air Force pilots.
Stearman RT-17
Originally transferred to civilian owners, the RT-17 biplanes were used to spray pesticides in the fight against agricultural pests. In place of the co-pilot's cockpit, a container with a volume of 605 liters was installed. And although the amount of water discharged at a time was small, the experience of "combat use" showed that in combination with a developed aerial reconnaissance network and total radio frequency of firefighting aircraft, with timely detection of a fire while its source is still small, even light aircraft can be very effective.
The first in the United States to create a serious fleet of firefighting aircraft began the authorities of the state of California, which suffers from fires every year in the summer. In 1954, the first deck torpedo bomber TBM Avenger, bought at a bargain price from the Navy, was refitted. Converting it into a fire engine turned out to be easy. All unnecessary military equipment and weapons suspension assemblies were dismantled from the plane. Tanks for water or extinguishing agent with a volume of about 1300 liters, together with a drain system, were placed in the vacated bomb bay. There were several tanks, this made it possible to minimize the harmful effect of water swing in flight, improve alignment and provide alternate or salvo water discharge, depending on the nature and length of the forest fire. The planes were painted in bright colors typical for fire brigades.
The Avengers were often called “water bombers”. In the 1950s, an entire air army of such "water bombers" was formed in North America, sufficient in number to man the air wings for a pair of aircraft carriers. The Avengers have had a very long life in firefighting. The US Forest Service and a number of companies such as Cisco Aircraft, TBM Inc, Sis-Q Flying Services and Hemet Valley Flying Services operated several dozen former “palubniks” until the early 90s, and in Canada they extinguished fires back in the 2000s.
The successful use of the Avenger as an air firefighter opened the way for other obsolete piston bombers in this field, which in the 50s in the United States formed a large surplus. The Air Force and the Navy abandoned them, private owners did not need multi-ton, gluttonous cars, and airlines preferred more economical specialized airliners to transport passengers and cargo. Even for nothing, within the framework of gratuitous military aid, there was no queue for piston bombers. The US allies preferred more flexible and cheaper to maintain single-engine vehicles such as the P-51 or A-1. Under these conditions, in the 50-60s, re-equipment into "flying water tankers" saved dozens of North American B-25, Douglas A-26, Consolidated B-24, Boeing B-17 bombers from being cut into metal. Compared to the Avenger, the two and four motor vehicles had a higher carrying capacity and reliability.
Dumping the extinguishing agent from the B-17
As the resource of the bombers from the Second World War was exhausted, the question arose of replacing them. After serving in the forest protection service, many planes took pride of place in museum exhibitions and starred in feature films. However, some of the rare cars continue to serve. So, until recently, the huge flying boat Martin JRM "Mars" was involved in extinguishing fires. In total, seven cars were built until 1947. Two "Mars" in October-November 2007 took part in extinguishing forest fires in California. In 2012, one car was decommissioned, while it was announced that it would go to the National Museum of Naval Aviation.
Martin JRM "Mars"
Despite their advanced age, the "Mars" proved to be very effective in extinguishing fires. Due to the large reserves of fuel, the duration of operation at one refueling in the intensive fire extinguishing mode is 6 hours, while the aircraft is able to perform 37 complete cycles of water intake and discharge.
The Davis-Montan aircraft storage base in Arizona has become an inexhaustible source of replenishment of the firefighting aircraft fleet. A significant part of the S-2 Tgaskeg and P-2 Neptune anti-submarines stored here were later converted into fire engines.
Dumping the extinguishing agent from the P-2 Neptune
Good takeoff and landing characteristics, unpretentiousness, relatively inexpensive spare parts and maintenance, large internal volumes - all this made them very attractive for firefighting services. Some S-2s and P-2s still fly in the United States.
In the 70s and 80s, the practice of replenishing the firefighting aviation fleet with obsolete Air Force and Navy aircraft continued. Naturally, jet bombers were no longer suitable for dropping water from low altitudes. The basic patrol P-3A Orion, military transport C-54 Skymaster and C-130 Hercules of the first modifications went into action. Civil aircraft DC-4, DC-6, DC-7 and even wide-body DC-10 were also added to their ranks, which airlines began to abandon as they were replaced by modern aircraft. As a result, a very diverse fleet of fire-fighting aircraft was formed in the United States, which is explained by the bargain prices of used aircraft. For firefighting aviation, the criteria for high fuel efficiency and comfort are not of paramount importance, it is much more important how much extinguishing liquid an aircraft can take, and how reliable and easy it is to maintain.
However, recently, due to a number of accidents caused by fatigue failure of the airframe structure, there has been a tendency to replace old aircraft that were not originally intended for extinguishing fires, which are more than 50 years old, with specialized machines. In the United States, firefighting services, unlike Canada, mainly use aircraft based on land airfields. This is due to the fact that large forests of industrial importance are located in the western United States, where water bodies suitable for landing seaplanes are quite rare. At the same time, instead of water, fire retardants are used as a fire extinguishing agent - solutions and suspensions, which are more effective and have a slower evaporation coefficient compared to pure water. Since ordinary water is far from an ideal extinguishing agent: in hot weather it quickly evaporates, and combustion is restored and continues with the same force.
In the United States, the main "striking force" of aviation firefighting detachments is currently heavy vehicles created on the basis of wide-body airliners of civilian airliners and military transport aircraft. The high carrying capacity makes it possible to partially compensate for the low productivity of airfield-based vehicles in comparison with amphibians.
For example, the Evergreens company operates a Boeing 747ST Supertanker, converted from a cargo B-747-200F, capable of dropping up to 90,000 liters of water in one pass. BAe-146 aircraft and converted KS-10 tanker aircraft are also widely used.
Since the 60s, helicopters with external spillways have been actively used for firefighting. The advantage of helicopters, in spite of high operating costs and limited carrying capacity, is the ability to fill water tanks in almost any reservoir in hover mode, as well as greater efficiency due to increased drop accuracy. It usually takes only a few seconds to fill the container. The first experiments in this area were carried out in 1957 on a light helicopter Bell 47. It delivered water in rubberized bags with a capacity of 250 liters, fixed under the fuselage.
Bell 47
An alternative, but rather rarely used method is to draw water into the internal tanks located inside the helicopter using a pump in hover mode. This method, for example, uses the fire-fighting version of the S-64 Skycrane helicopter.
S-64 Skycrane
Until 1961, helicopters were almost never used to protect forests from fires in the United States, since there were few of them in commercial airlines, and the military allocated helicopters only in critical situations when forest fires became uncontrollable. After the “helicopter boom” began in the world at the end of the 60s, and affordable and reliable models appeared on the civilian market, the use of helicopters in forestry became commonplace.
A variety of light-engine aircraft are actively used for air patrolling and timely detection of fires. In the United States, they are called birddogs - "bloodhound birds." If earlier the search for fires was carried out visually, now the equipment of the scouts necessarily includes an infrared system for front view FUR, capable of automatically detecting open fire and "seeing" through the smoke, both during the day and at night. In addition to standard communication equipment, satellite navigation systems and real-time data transmission equipment are installed on air reconnaissance aircraft. This allows, even in flight, to drop the coordinates of fires on ground command posts and quickly begin to fight the fire. Until now, light patrol aircraft are a more reliable and operational means of controlling forest fires in comparison with a satellite monitoring system. However, more and more often unmanned aerial vehicles are used for these purposes.
Google earth snapshot: OV-10 Bronco and P-2 Neptune fire planes at Chico airfield in California.
The former OV-10 Bronco anti-guerrilla aircraft, converted into patrol aircraft, are very popular among fire pilots in the United States. While fighting fires, the Bronco, with excellent maneuverability and good visibility from the cockpit, are used as air command posts, coordinating the actions of ground forces and firefighting aircraft.
Air Tractor AT-802 Fire Boss
The Air Tractor AT-802 Fire Boss aircraft, equipped with special Wipaire floats, deserves a special mention. This relatively small aircraft has several tanks for extinguishing composition with a total volume of 3066 liters. The presence of floats and excellent take-off and landing characteristics make it possible to take water from small reservoirs that are inaccessible to other, larger seaplanes. The AT-802 Fire Boss - "Lord of Fire" - thanks to its high reliability and efficiency at low operating costs, has become a real bestseller of Air Tractor, also known for its agricultural aircraft and light attack aircraft.
During large forest fires, when a state of emergency is declared in the territory of certain states, as in other countries, in the United States, at the request of the National Inter-Agency Fire Center (NIFC), aircraft of the Air Force, Navy and National Guard are involved in the fight against fire. Most often, military transport C-130 is used to discharge water. The MAFFS II onboard system for extinguishing large ground fires was created especially for aircraft of the C-130H / J Hercules modifications. System modules and capacities can be installed on military transport aircraft within 4 hours.
In California, which often suffers from fires, the Bell V-22 Osprey tiltrotors belonging to the US ILC have performed very well. These devices combine the separate advantages of an airplane and a helicopter. In terms of carrying capacity, the Osprey surpasses most helicopters, at the same time it is able to draw water into the harness in hover or at low speed.
Several years ago, the US Forest Service (USFS), based on the experience of using Russian fire aircraft during extinguishing large fires in Spain and France, expressed a desire to purchase or lease several Be-200ES. Forestry specialists noted that the Be-200ES has a shorter approach time to the fire site, a longer range, and a better view from the pilot's workplaces compared to the widespread Canadair CL-415 amphibious firefighting aircraft. Due to its high thrust-to-weight ratio, the Russian firefighting aircraft is capable of taking water in mountain lakes on courses inaccessible to other seaplanes. The maneuverable characteristics of the Be-200ChS allow it to carry out missions in conditions of high turbulence. Unfortunately, due to circumstances beyond the control of the Russian side, this promising deal never materialized. Obviously, politics and lobbying interests of foreign manufacturers intervened in the matter.
Unlike most of the United States, Canada is rich in water bodies. Therefore, in Canada, especially in the French-speaking provinces, in addition to land-based firefighting aircraft, there are many amphibians, float seaplanes and flying boats. The practice of fighting forest fires has shown that a seaplane has serious advantages over airfield-based aircraft, since it can draw water on planing in any nearby large body of water. At the same time, the time of delivery of water to the fire site is significantly reduced. For land vehicles, equipped airfields with special ground infrastructure are required for the delivery of water and the manufacture of extinguishing liquids and their refueling.
In 1950, De Havilland Beaver floats began to be used in Canada, followed by DHC Beaver and DHC Otter - they had tanks placed inside floats filled with water on the ground or on planing along the surface of a reservoir.
DHC Otter
Since 1958, the amphibious PBY-6A Canso (the Canadian version of Catalina), which have been removed from service, began to enter the Canadian fire service. On these machines, suspended tanks with a capacity of 1350 liters were placed under the wings. Later, additional tanks began to be installed inside the fuselage, while the water supply increased to 2500 liters. In 1971, the Canadian Catalins underwent modernization, they were equipped with two water tanks with a total capacity of 3640 liters and a system for supplying special chemical substances to the tanks - preventing the rapid evaporation of water. This version of the amphibian was named Canso Water Bomber - "Kanso water bombers".
In 1959, FIFT purchased four Martin JRM Mars giant flying boats in the United States. They became the largest Canadian firefighting aircraft and were used until the early 2000s.
But the most optimal was the Canadair CL-215 amphibious aircraft. It first flew in October 1967 and was specially designed to extinguish forest fires from the air, taking into account the operating experience of previous models. The aircraft turned out to be very successful and was a success both in Canada and on the foreign market. Its serial production continued until 1990, with a total of 125 amphibious firefighters built. Gradually, the CL-215 replaced all the Catalins decommissioned after their service life was depleted. Initially, the aircraft was powered by Pratt & Whitney R-2800 piston air-cooled engines with a capacity of 2,100 hp. each.
Canadair CL-215
Firefighting aircraft Canadair CL-215 especially distinguished themselves in May 1972. Then the crews of several amphibians, after receiving information from a patrol aircraft, despite dry windy weather, managed to stop the spread of a strong fire moving in the direction of the city of Val d'Or. In the zone of fire spread there were a railway station, tanks with liquefied fuel gas, an oil storage and the city itself. In total, six aircraft took part in the fight against the fire, with the first two amphibians arriving within 15 minutes after receiving the alarm. Water on CL-215 gliding was taken from a nearby lake, making discharges at intervals of one minute. Two hours later, the fire was stopped a few tens of meters from the railway station.
With the accumulation of operating experience, the modernization of the aircraft was ripe, and in the late 80s a modification of the CL-215T with turboprop engines appeared, and in 1993 the CL-415, an improved version with new avionics, tanks increased to 6130 liters, improved aerodynamics and an upgraded system plum. The aircraft is equipped with a Pratt & Whitney Canada PW123AF theater with a capacity of 2,380 hp. In addition to the water tanks, the aircraft has tanks for concentrated fire fighting foam, as well as a mixing system.
Canadair CL-415
The capabilities of the amphibious CL-415 are not limited to water discharge, this aircraft can also be used to deliver rescue teams and special equipment and perform search and rescue operations in disaster areas. After conversion into a transport and passenger version, its passenger capacity is 30 people. To date, 90 Canadair CL-415 amphibians have been built.
The practice of using aircraft in fighting forest fires has shown that they have significant advantages over ground-based means. Firefighting planes and helicopters can quickly reach the source of fire in any place, including where access from the ground is simply impossible, and start extinguishing before the fire has spread over a significant area. The use of aviation requires significantly fewer people and is often cheaper than fighting fire on the ground. This minimizes the risk of death and injury to personnel involved in the fight against the fire element. Trends in the development of firefighting aviation in the United States and Canada demonstrate that specially designed aviation technology and equipment is becoming more and more in demand, and obsolete aircraft converted from decommissioned ones are gradually becoming a thing of the past.
