RESULTS OF A STUDY OF FOREST FIRE EXTINGUISHING CASES USING DIFFERENT TYPES OF AIRCRAFT

For over 18 years, New Impulse Technologies has been conducting a study to determine the most effective forest fire extinguishing by means of aircraft. The practice of extinguishing forest fires by Russian and Ukrainian aircrafts U-2 (200 kg of water onboard), AN-2 (1200 kg), BE-12 (6,000 kg), BE-200 (12,000 kg), AN-32P (8,000 kg), IL-76 (42,000 kg) has been studied. The study covered all climatic zones existing on the globe. Pilots of the Russian state aviation detachment Emercom, who have experience of extinguishing forest fires in any spot on the Earth, as well as scientists of the Russian scientific and research institute for fire defense, scientific and research institute of forest, specialists and scientists of New Impulse Technologies took part in the studies. To study the effectiveness, several dozens of tests have been performed using different aircraft on special proving grounds in Russia, which were equipped with special devices to measure the parameters of water streams discharged from aircraft.

Below are the results of a theoretical and experimental study of dependence of water discharge parameters by different aircrafts on flight parameters, set forth in a popular and brief form. To study the influence of aircraft flight parameters on characteristics of ground distribution of the water discharged from aircraft and water aerosol dispersity the following varied: aircraft types, flight height, aircraft speed during the discharge, the discharge in a horizontal flight or in a flight with increasing speed, volley and consecutive discharge. The spatial and surface distribution of the liquid discharged was evaluated, and disperse composition of water drops was studied. The following two factors deserve particular attention:

1. The highest effect when extinguishing forest fires is achieved when big water drops reach the fire area. Big drops fall only within the first seconds after discharge. The water mass that extinguishes fire is mainly in big drops. Drops having a size of over 0.5 mm contain over 70% of the total water mass. In the initial moment of drops falling on the ground the main portion is comprised of big drops having a diameter of 1 to 2 mm. Then, drops of medium size (with a diameter of 0.5 to 1 mm) start to prevail, and further – drops with a diameter of 0.2 to 0.3 мм [5].

2. Infrared measurements of temperature fields of burning centers during and after the liquid discharge have shown that the influence of water aerosol leads to considerable reduction of the burning intensity of forest burning materials. Upon the completion of the influence the burning intensity restores gradually.

To solve the problems related to these two factors, the following conditions should be performed:

1. The minimal speed of the aircraft’s movement during the water discharge and minimal flight height. The discharge speed should not exceed 240 km/hour. With the increase of the aircraft’s speed and height of water discharge, water streams break, the number of big drops decreases, and the extinguishing effectiveness in some cases becomes equal to naught.

2. Refusal of single extinguishing and transfer to conveyor extinguishing using several aircrafts. The tests have shown that even the most powerful IL-76 aircraft at an instant discharge of 40 tons of water does not secure extinguishing of a forest fire. In several minutes the temperature of smoldering trees raises and the fire continues. An adequate extinguishing can be secured only by two or four aircrafts with a periodicity of several minutes discharging water at the same spot of a forest fire.

For effective conveyor extinguishing an electronic detailed map of the whole aircraft’s flight should be created indicating the water discharge spot, the aircraft’s speed, and height of water discharge.

It is impossible to perform these two important tasks by means of big jet aircrafts of IL-76 type due to the following reasons:

1. The speed of IL-76 aircraft at water discharge cannot be less than 280 or 300 km/hour. 2. The discharge height cannot be less than 100 meters. 3. The huge time of charging the aircraft with water in the conditions of a big airport with a solid

covering only, taking several hours. At present, the state Russian company Emercom only can spend huge money to maintain several IL-76 aircrafts and use conveyor extinguishing of two or four IL-76 aircrafts. BE-200 aircraft cannot use rivers for water intake, this aircraft can safely intake water in the ocean only or in big lakes and on airdromes with solid covering. The high speed of discharge, over 270 km/hour, neither allows creating a water stream of big drops. During the whole time of the study the U-2 and AN-2 aircrafts have not performed an adequate extinguishing at least once. Small aircrafts having a water quantity of less than 6,000 kg are inapplicable for extinguishing due to two reasons:

1. The amount of water discharges is too little for extinguishing. 2. Low flight speed and small flight radius. This aircraft will spend too much time for the flight

from the place of water intake to the fire.

The most optimal and effective extinguishing method can be performed only in case of extinguishing using several AN-32P aircrafts.

Positive distinctions of this aircraft are as follows:

Possibility of using natural ground airfield.

1. High flight speed from the airfield to the fire location, 530 km/hour. 2. Low flight speed during the water discharge of ~190 km/hour and low water discharge height

allow creating a cloud of big water drops. 3. Little time for water filling of several minutes. 4. 8,000 kg of water onboard. 5. Superpower engines and special propellers allow performing complex maneuvers and secure

high flight safety. AN-32P can perform a take-off, flight, and landing with a single working engine only in the conditions of tropical heat.

Electronic navigational equipment of AN-32P aircraft allows applying a semiautomatic mode of conveyor forest fire extinguishing using the data of air scout. Semiautomatic method of extinguishing allows minimizing fuel consumption rate for the flight and extinguishing. Semiautomatic method of conveyor extinguishing is possible to perform in special cases using only one AN-32P aircraft equipment with special devices. The method was developed by New Impulse Technologies company.