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Home | Update | LATEST ISSUE | Gallery | FR Profile | Datafiles | FR 7/98 MIL MI-26: THE RUSSIAN GIANT by Karl Schwarz Especially when size was concerned the Soviet aircraft designers were always eager to lead the way. For that reason, the Moscow based Mil design bureau was at the top of helicopter design for several decades. The Mi-6 dating from the fifties was followed by the Mi-10 external lift helicopter and the monstrous Mi-12 with side-by-side rotors. Finally the Mi-26 first flew in 1977, and will probably hold the title of being the worlds most powerful helicopter for a long time to come. But gigantism was not an end in itself. The design of the Mi-26 resulted from logical requirements. When Marat Tischtschenko took over from Michail L. Mil, who died in 1970, the Soviet government demanded a heavy transport helicopter to exploit the resources in the vast aeras of Siberia which were very difficult to access. The new design was to be able to carry large equipments from railway stations and airports over distances of several hundred kilometers into the Tundra. This also had to be safely possible at higher altitudes and most importantly in severe weather conditions. Of course, in the times of the cold war, nothing happend without a view on possible military missions. Therefore the cargo compartment is also designed to hold light amoured vehicles and troop carriers together with their crews. Tischtschenko and his engineers studied various configurations to fulfill these specifications, including tandem rotors and side-by-side rotors like they are fitted to the Mi-12. In the end the designers chose a conventional layout with main and tail rotor, making the Mi-26 appear rather normal with the exeption that everything is 50 per cent or so larger than every other series-produced helicopter (apart from the Mi-6). The cargo compartment for example has a length of twelve meters, a width of 3,25 meters and a height of three meters which places it in the same class as the Lockheed C-130 Hercules or the Transall C160. The helicopter is loaded from the rear, the same way as most transport planes. Vehicles can drive directly into the cargo hold via an hydraulic ramp. Two hoists with a capacity of 2,5 tons each handle bulky loads just as it is usual practise with Russian designs. According to its manufacturer the Mi-26 is able to carry a payload of 20 tons either in the cargo compartment or as an external load hooked on a suspension just below the gearbox. A lot of power is necessary to move such an extensive mass. The two Progress (former Lotarev) D-136 free-turbine turboshafts, mounted side by side above the cabin, are rated at 11400 shp each, establishing a good reserve in case of high outside temperatures, since the gearbox is designed for a maximum of 19725 shp. In case one engine fails, the other is automatically powered up to full throttle. One of the brilliant achievements of the Mi-26 is the VR-26 main transmission designed by the Mil bureau itself. Despite the enormous performance the transmission weighs 3,5 tons, which still is acceptable though it corresponds to around ten percent of the total empty weight. While Mil did not use titanium in the construction of the transmission the dsign team incorporated it in the large rotor head which is equipped with the usual flapping and drag hinges as well as hydraulic drag dampers. For the first time ever, eight rotor blades were used on a helicopter, enablling a comparatively small rotor diameter and reducing noise and vibrations. Each blade has a one-piece tubular steel spar and GFRP aerofoil shaped full-chord pockets which are honeycomb filled. An electric de-icing system allows missions to be flown even in severe weather. The five-bladed tail rotor has a diameter of over seven meters and would fit as a main rotor for smaller helicopters. The fuselage is built rather conventionally and in a robust way just like the non-retractable and unfaired landing gear. Furthermore the helicopter is equipped with an auxiliary power unit below the cockpit to render possible autonomous operations far away from the home base. All of the Mi-26's systems are easily accessible. During engine and rotor maintainance the opened fairings also act as working platforms. The heavy-lift helicopter is flown by a crew of five, consisting of pilot and copilot sitting at the front of the spacious cockpit, the navigator and flight engineer at the instrumentation consoles directly behind, and finally the loadmaster. The television monitor on the instrument panel is very unusual since it is connected to cameras located on the tail, in the cabin and below the fuselage (showing the external load). The autopilot, doppler navigation and radar altimeter further facilitate flight operations. The first prototype of the Mi-26 was finished in 1977 and first flew on December 14th for a short hover. The first test flight of longer duration happend in February 1978 and included the first transition into horizontal flight. First deliveries to the Soviet armed forces began in 1982/83 after extensive tests. Since then between 200 and 300 helicopters were built by the Rostov on the river Don plant. Not all of these were put into service in the USSR. A small number of Mi-26's were exported to India. Surprisingly there seem to have been rather few technical modifications over the years, although several specialised variants are available. The civil version, called Mi-26T, for example is able to carry either a 15000 litres water tank in the cargo compartment or a water bucket as external load and therefore can be used as a fire-fighting helicopter. For passenger duty a variant containing 70 seats, two toilets and additional windows is also offered. Rostvertol further shows in its brochures possible usages like the towing of boats equipped with geological sensors or special frames with tail units for stabilising external loads, thus making faster flying speeds possible. As a flying crane the Mi-26 can be fitted with additional cabins either at the tail, next to the fuselage or below the fuselage. An additional pilot has a much better view from there to precisely position the external loads. The price of the Mi-26 is supposed to be around ten to twelve million US dollars (17,5 to 21,3 million German marks), but no sales were annonced in recent years whereas the leasing business is booming. Like the Antonov An-124 freighter the Mi-26 is often offered for difficult missions in Asia, South America and Europe. With his incredible performance the Mi-26 will remain without competitors for a long time to come. From page 44 of FLUG REVUE 7/98 Home | Update | LATEST ISSUE | Gallery | FR Profile | Datafiles | FR 7/98 Copyright 1998 by Motor-Presse Stuttgart. All rights reserved. Last updated June 9, 1998 FLUG REVUE, Ubierstr. 83, 53173 Bonn, Germany