Aerial firefighting is today a normal part of the fire protection system in every developed country. Its roots can be traced back to the years after World War II, when the first attempts to extinguish fires using aircraft occurred. Since then, modified ex-military aircraft have been replaced on the market by special firefighting models. Today, one can find aerial firefighting aircraft in the majority of European countries, in the USA, Russia and other states.
The initial use of an aircraft for firefighting purposes remains unclear with several nations claiming to have been the first. One of the oldest historical mentions can be traced to the State of California, where ex-military aircraft were used for fire monitoring in the very early 1920s. The pre-WWII era was very much focused on exploring the possible use of aerial support. Even then some interesting and progressive efforts appeared, such as bombing ground fires with wax-paper bags filled with water. Nevertheless, it was only after WWII that aerial firefighting found significant interest on the part of fire brigade headquarters all around the developed world. With thousands of surplus aircraft especially in the US, fire brigades started to use ex-military aircraft for firefighting.
In this new role, it was mainly bombers that demonstrated their multipurpose character, as their bomb bay provided sufficient space for a water tank and did not require heavy structural modification. In parallel, lighter types modified for crop spraying and dusting were found suitable also for dropping water. With the first regular helicopters in the army being phased out for newer types, the rotary wing also helped to define the paths for future firefighting. Helicopters were used as command posts, or for hose laying and later even for direct water dropping. Nevertheless, it was only in the mid-1950s that aerial fire-fighting became an integral part of the rescue system. The lead position in the development of new methods was occupied by Canada trying to protect its large forested areas, with USA following the trend. Until the mid-1970s ex-WWII and Korean War models were heavily used with some relics still in operation as late as the early 1990s.
The B-25 Mitchell bombers were among the most interesting, of which several dozens were equipped with 4-000 litre water tanks. In the mid-1950s there appeared to be a true breakthrough in aerial firefighting. Some of the water-carrying bombers were equipped for the first time with fire retardants based on sodium calcium borate. When mixed with water this substance increased extinguishing efficiency several times over. Nevertheless, practical use showed it caused chemical burns on those affected and on animals on the ground and sterilised the soil. Therefore, after further research, new retardants based on ammonium polyphosphate were introduced; these helped to extinguish blazes without any negative side effects. Chemical agents can reduce the volume of water needed by up to 50%. In the 1980s the western world started to focus on higher reliability and safety of fire department aircraft and single-engine platforms started to be phased out in favour of multi-engine types.
LOW FLYING JUMBO
Since the 1960s the majority of the US Fire Department aircraft inventory came from US Navy, Air Force and Army surpluses. This for example is how the Grumman S-2 Tracker and Lockheed P-3 Orion planes came into their new role. Among surely the most interesting planes, the Martin Mars amphibian planes are worthy of mention. Of six prototypes ordered by the Navy during WWII, four were later converted to a firefighting role with 27,000 litre internal tanks. Two planes are still in use and represent the largest firefighting amphibian planes ever built.
They can scoop up water in less than 30 seconds and can drop all of it in less than 10 seconds. It is no wonder that it is nicknamed “the airborne tsunami”. There are many special firefighting companies in the USA, which operate a varying mix of planes. Of the most interesting, one might mention the Evergreen SuperTanker built on the basis of the Boeing B747 Jumbo Jet. This plane with incredible 90,000 litre tanks is equipped with a pressurized water disposal system allowing it to deliver over 50 litres of water per square meter if the drop is made during ultra-low level flight at an altitude of 500 metres. And it is definitely not an easy task to fly a plane of the size of the B747 quite so low.
Just for comparison of the SuperTanker leaders, the second largest tank used is in a modified Douglas DC-10 with “only” 45,000 litres of water and no pressurized drop capability. To boost the fire department system, the US Army and National Guard operate a MAFS (Modular Airborne Firefighting System) allowing them to install a 10,000 litre tank into any C-130 Hercules. This system allows it to drop all its water in just 5 seconds! With Canada playing a leading role in firefighting technology development since the beginning, it is no surprise special firefighting planes were built there. Unlike other models the Canadair CL-215 and CL-415 planes are designed for the role from beginning. Both allow scooping at the water surface and are widespread at home and abroad, with more than 200 planes in use.
Due to their ability to land anywhere and not be dependent on airstrips, helicopters are heavily used by US fire departments. They normally carry water in a plastic bucket called a “bambi bucket”. The capacity of the bucket varies from 500 litres with smaller types such as the Bell 206 up to 10,000 litres with the CH-47 Chinook or the CH-53 Super Stallion. The big advantage of the helicopter is the precision of the water drop, with a higher kinetic effect from the water. While the normal (i.e. other than SuperTanker) fixed-wing water bombers can drop some 1.5 to 4 litres of water per square metre, helicopters can exceed 10 litres; in such cases the water quenches the blaze not only through its extinguishing nature, but also through the kinetic energy of the falling drops.
US fire departments in many states operate their own helicopters such as the SH-70 Fire Hawks used by the Los Angeles County Fire Dept., but in many states the army and national guard units support the firefighting system with regular helicopters. Probably the most known type is the Sikorsky S-64 SkyCrane “flying frame” model able to drop over 8,000 litres of water. Somewhat rarer are the AH-1 FireCobra ex-attack helicopters modified for fire monitoring and surveillance with FLIR cameras.
FIRST WITH HELICOPTER
The second country to evaluate building dedicated firefighting aircraft was the USSR. Its fire departments started to use Mi-4 helicopters back in the late 1950s and equipped several helicopters with a water tank and hoses for dispersal. The effectiveness of such system was obviously very low. Thus it was a big surprise in 1967 when they debuted the Mi-6PZh firefighting variant of the giant Mi-6 helicopter at the Le Bourget Paris Air Show. It was equipped with front and down firing water cannons and internal water tanks with pumps and became the world’s first dedicated firefighting rotary model. The tank held 12,000 litres of water and the type was the most advanced aerial firefighting system of its time. The Mi-6PZh was frequently displayed at international air shows and several times used for real firefighting with one even crashing during support for the French fire brigades. Later the type saw limited use in the USSR and was also equipped with underslung buckets with a total capacity of 9,000 litres of water.
In 1970s many Soviet fire departments started to use the ubiquitous Mi-8s and later Mi-8MTs for fire extinguishing with the help of an underslung bucket. Unlike the light western type, the Russian one was originally made of metal and thus greatly reduced lifting capacity. After a little use of US products as an inspiration, in the 1980s the first rubber and synthetic material buckets were introduced. After the break-up of the USSR, even Western suppliers of bambi buckets started to modify their products for Russian helicopters. These were made in various sizes up to 5,000 litres for the Mi-8 and Mi-8MT models and also 15,000 litres for the giant Mi-26 type. The latter model was also presented in the Mi-26TP variant with internal 15,000 litre tanks, but it failed in the end to achieve any sales.
When speaking about helicopters, the true star of fire extinguishing is the Kamov Ka-32 model. Its co-axial rotor scheme provides the best lifting performance of any helicopter and Kamovs are widely used for firefighting in Canada, Spain, Portugal and of course the CIS countries. With a footprint of some 70% of the Mi-8MT, the Ka-32 can lift a 5,000 litre bambi bucket (while on the Mi-8MT it can only be filled up to 4,000 litres due to the limit on the underslung weight). In the 1990s special Ka-32 variants with US-made FireAttack water cannon were introduced. The cannon may be used for fire extinguishing in high-rise buildings and this model was adopted by several CIS countries.
Several fixed-wing planes are also used for firefighting in Russia. The most widespread is the Antonov An-2 biplane where the crop sprayer model is upgraded for its firefighting role. Later the much larger An-26 was also modified into a water bomber with a few operated by Russia and Ukraine. In parallel with developments in the USA, Soviet and Russian amphibious planes were also converted for their new role. While the Beriev Be-12 amphibian plane was able to carry 6,000 litres of water, the jet-powered Be-200 can accommodate up to 12,000 litres and is the only jet able to operate from surface water. A very promising Beriev A-40P project was abandoned after the fall of the USSR. The last firefighting special in Russia is the transport Ilyushin Il-76 plane converted by the installation of a MAFS-like system and a 49,000 litre water tank. It is the second largest water bomber able to dispose of all of its water within 10 seconds.
Text: Jakub Fojtík
Photo: Author and author´s archive