TsAGI investigates issues to increase the altitude of water discharge at fire airplanes
3 April 2019
The Il-76 crashed in summer 2016 during water-bombing in the Irkutsk region. It was one the best crews of EMERCOM of Russia. The water bomber worked at a low altitude in strong smoke and difficult terrain. Perhaps the pilots could have escaped this situation should they have risen above. But could they then take on the task of fire suppression?
Specialists of the Zhukovsky Central AeroHydrodynamic Institute (TsAGI, a member of the National Research Center “Zhukovsky Institute”) studied the altitude effect on the effectiveness of the irrigation line.
At the first stage of the work the scientists analyzed the available data of the natural liquid discharges from real aircraft, and the results of earlier theoretical and experimental research at the High-speed installation (TsAGI’s water aerodrome in Dubna). In addition, they studied the aerohydrodynamics of the liquid drain from different types of air tanker containers, towed with the speed, required under simulation.
In 2018 there was organized a cycle of simulated experiments to study the water dropping from the altitude of more than 100 m. To carry out these researches TsAGI’s scientists developed a new technique for the collecting of extremely small quantities of liquids. The technique was based on the usage of coordinated hygroscopic elements located at the bottom of the pool of the towing installation. “Using the 1:55 scale model with the water container of 125 m3, this system allowed to determine with high accuracy the distribution of the dropped water on the area of 20 m2,” said Chief researcher at the TsAGI’s Department of computational and industrial aerodynamics, doctor of technical sciences, academician of the Russian Academy of Natural Science, Oleg Shorygin.
As a result, it was found that the water discharge altitude can be increased from 60 to 90m without a significant loss of the effectiveness of fire extinguishing for the medium-lift aircraft (up to 14 tons of water), and from 75 to 140 m. for heavy water bombers (up to 40 tons of water).
The internal fluid hydrodynamics in a container of a heavy aircraft was changed during the tests. It ensured a more uniform water discharge and extended the irrigation strips from 500 to 1200 m.