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Project 1240 Urugan class [NATO Sarancha]
Guided Missile Corvette

Marine vehicles are categorized as either displacement craft or dynamic-lift craft. Displacement craft derive their lift from buoyancy (displacement). Dynamic-lift craft derive their lift dynamically, such as by hydrofoils or planing surfaces. When the speed of the boat increases, the wings can provide buoyant force to lift the boat out of the water, forming the so-called hydrofoil flight or navigation, thus largely reducing drag in the water and increasing the navigation speed. The drag of displacement craft is primarily frictional and wavemaking. The drag of dynamic-lift craft is primarily frictional and induced (drag induced by lift). In high-speed craft of either type, frictional drag is normally more than half the total drag.

Hydrofoil craft have been used where operation above 45 knots is desired. However, such devices are complicated, prone to failure, require constant adjustment, require a highly knowledgeable operator, are costly, and add weight.

The idea of reducing hydrodynamic drag by lifting the hull of a ship from the water has long attracted the designers of warships. In the late 1940s and early 1950s, various wing devices were tested, but positive results were not achieved. But the idea did not die, and at the end of the 50s they returned to it again, but already at a qualitatively new theoretical and design level. The result of the work carried out was the construction and testing of a small torpedo boat with a lightly loaded bow wing and side stabilizers, as well as an experimental boat with a similar wing and a controllable transom plate. The use of the latter improved the behavior of the boat while driving at high speed in rough seas.

However, the lightly loaded wings turned out to be non-seaworthy. Scientists and designers saw the solution to the problem in equipping sea-going vessels with deep-submerged hydrofoils with automatic lift control. This direction received its theoretical justification and practical implementation already in the 70s. Another important event that made it possible to successfully carry out the design and construction of large ships on hydrofoils was the creation and widespread introduction into the practice of shipbuilding of light and economical gas turbine power plants with high specific indicators. Such an installation with two 18,000 hp engines made for a small rocket-firing ship.

The results of deep theoretical and experimental research formed the basis for the development of projects for ships for various combat purposes. Particular attention was paid to improving the systems of automatic control of the lifting force of the wing devices to improve the seaworthiness of ships. In order to check the correctness of the design decisions taken, two experimental ships were built: a small missile (project "1240 Uragan") and a small anti-submarine (Project 1141).

The design of a small rocket-firing ship was preceded by the construction of a full-scale model on a 1:2 scale, the trial operation of which showed good results. Later repeated in the passenger version, it was named Typhoon. A wing device with automatic lift control, providing stabilization in height above the water surface, roll and trim, in combination with a powerful gas turbine unit, allowed the ship to reach speeds of more than 50 knots and use weapons in sea waves up to 5 points inclusive.

Construction, testing and commissioning of the experimental MRK pr. 1240 "Uragan" was planned at the Nevsky Marine Plant SME, which by 1970 became part of the Leningrad Primorsky Plant. To carry out the construction of the ship at this plant, reconstruction was completed in terms of the construction of a new boathouse, as well as a number of works on technological equipment, including the construction of a launching device. In this vessel, the novelty of many technical solutions was striking. At the time of construction, it was the largest hydrofoil ship in the world. The main power plant consisted of two gas turbine engines with a capacity of 18,000 hp each. Each one. Through gearboxes located in the corner columns, she rotated propellers of the tandem type. At low speed, the nose wing (made of titanium), both columns with propellers rose out of the water. Movement in this mode was carried out by water cannons powered by two diesel engines.

To control the ship's maneuvers when mooring to the pier, sailing in narrowness in the displacement position with raised KU on MRK pr. 1240, trolling engines (DMX) are installed, consisting of two diesel-geared units "DRA-211" and two water-jet propellers GD-1240 with a two-stage axial pump and a reversible steering device. To control the ship's maneuvers when mooring to the pier, sailing in narrowness in the displacement position with raised KU on MRK pr. 1240, trolling engines (DMX) are installed, consisting of two diesel-geared units "DRA-211" and two water-jet propellers GD-1240 with a two-stage axial pump and a reversible steering device.

The construction of the Uragan MRK began in 1972, by the fall of 1975, a trolling complex was mounted on it and tests were carried out in displacement modes. In 1976, titanium hydrofoils manufactured at the Northern Machine-Building Enterprise were mounted and sent to Liepaja for testing. In 1978, the ship was transferred to the Black Sea and in 1981 transferred to the pilot operation of the Black Sea Fleet. In the winter of 1981, near Sevastopol, comparative sea trials of the Uragan MRK and the Sokol MPK, similar in displacement and speed, also had hydrofoils, but with a more simplified stabilization system and did not have a wing lift device, which significantly complicated operation.

The ship had powerful strike and anti-aircraft missile armament, as well as a rapid-fire automatic artillery mount AK-630. During its life, the MRK-5 conducted two rocket firing with the main missile system "Malachite", showing excellent seaworthiness during the tests. Also, the RTO had a high speed. "Hurricane" showed higher seaworthiness, its wing scheme was more perfect.

This experienced RTO turned out to be very difficult to operate. The hydrodynamic characteristics of lift producing hydrofoil structures are very similar to the subsonic aerodynamic characteristics of aircraft wings. Thus, it has been possible to adapt many airfoil theories and computational techniques to hydrofoil section designs. However, there exists a major distinction between hydrofoil structures and aircraft wings. Operated below the free surface, a hydrofoil will develop vortex cavitation and surface cavitation on the foil or blade above a certain critical speed. Cavitation inception occurs when the local pressure falls to or below the vapor pressure of the surrounding fluid. The major obstacle to achieving high sustained speeds in water is the occurrence of cavitation with its many detrimental effects. Consequently, the design philosophy for hydrofoil sections has been governed by the requirement to provide the required lift/thrust at a specified design point while ensuring adequate structural strength (especially at thin leading and trailing edges) for all operating conditions; and to avoid or minimize cavitation or the detrimental effects of cavitation.

To maintain a reasonable efficiency, the lower limit for application of supercavitating hydrofoils is approximately 50 knots. Below these speeds, only a partial cavity develops resulting in cavity collapse forward of the trailing edge causing buffeting and erosion. Additional obstacles associated with use of supercavitating hydrofoils include: the high angle of attack needed to generate a reliable, steady cavity compared to subcavitating hydrofoils, results in large drag and low efficiency, especially at off design speeds; due to increased form drag at low speeds the lift-to-drag ratio is small compared to subcavitating hydrofoils, consequently, supercavitating hydrofoils have difficulty generating sufficient lift for take-off.

Unfortunately, the Hurricane was ahead of its time, the industry was not ready for the mass production of such ships, and the navy was not ready for their operation. Therefore, the serial construction of MRK project 1240 "Uragan" was not carried out. In 1990, he was expelled from the Navy in connection with the delivery to the OFI for disarmament, dismantling and sale. In 1992 it would have been cut into metal in Sevastopol. In the creation of this ship, along with the designers who solved a complex scientific, technical and engineering problem, the merit of the plant workers, and first of all, the general directors G.G. Polukhin and V.K. Kosenkov, the chief engineer A.A. Ponomarev, the builders of M I.Ukrainsky, I.I.Kostinsky, M.I. Tuzov, V.I.Sibirtsev, V.I.Mertsalov.



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Page last modified: 15-06-2021 19:32:48 ZULU