Mil Mi-26 - Design and Development

Design and Development

Following the incomplete development of the heavier Mil V-12 (also known as Mi-12) in the early 1970s, work began on a new heavy-lift helicopter, designated "Project 90" and later allocated designation Mi-26. The new design was required to have an empty weight less than half its maximum takeoff weight. The helicopter was designed by Marat Tishchenko, protégé of Mikhail Mil, founder of the experimental OKB Mil design bureau.

The Mi-26 was designed as a heavy-lift helicopter for military and civil use, and was to replace earlier Mi-6 and Mi-12 heavy lift helicopters, with twice the cabin space and payload of the Mi-6, then the world's largest and fastest production helicopter. The primary purpose was to move military equipment like 13 metric ton (29,000 lb) amphibious armored personnel carriers, and mobile ballistic missiles, to remote locations after delivery by military transport planes such as the Antonov An-22 or Ilyushin Il-76.

The first Mi-26 flew on 14 December 1977. The first production aircraft was rolled out on 4 October 1980. One production aircraft was destroyed during pre-delivery single-engine emergency landing procedure testing, but there were no casualties. Development was completed in 1983, and the Mi-26 was in Soviet military and commercial service by 1985.

The Mi-26 was the first factory-equipped helicopter with an eight-blade rotor. It is capable of flight in the event of power loss by one engine (depending on aircraft mission weight) thanks to an engine load sharing system. While it is only slightly heavier than the Mi-6, the Mi-26 can lift up to 20 metric tons (44,000 lb). It is the second largest and heaviest helicopter ever constructed, after the experimental V-12. The tail rotor has about the same size and thrust of the MD 500 main rotor.

The Mi-26's unique main gearbox is relatively light but can absorb 19,725 shp, which was accomplished using a non-planetary, split-torque design. Because Mil's normal gearbox supplier said that such a gearbox couldn't be designed, the Mil Design Bureau designed the VR-26 transmission itself.

In July 2010 proposed Russian-Chinese development of a 33-ton heavy-lift helicopter was announced.

Russian helicopter manufacturer, Rostvertol is in the process of refurbishing and upgrading the entire fleet of Mi-26s serving in the Russian Air Force. The fleet is estimated to number around 20 helicopters. Refurbished and upgraded aircraft will be comparable to an up-to-date variant: Mi-26T. Contract completion is planned for 2015. The same contract covers the manufacture of 22 brand new Mi-26T helicopters. As of January 2012, eight new-production helicopters have been delivered to operational units.