Mil Mi-26 Halo

   The Mi-26 (NATO designation Halo) is a twin-turbine heavy-lift helicopter. It is the world's largest production helicopter. The Halo's development started in the early 1970s. The designer's goal was to produce a helicopter with a load capacity twice that of any contemporary helicopter. The first Mi-26 Halo prototype flew in December 1977 and was first displayed at the Paris Air Show in 1981. In 1982, Russian squadrons received their first Halos, which were not fully operational until 1983. In 1986, India was the first country to purchase a Halo. Since then Halos have been sold to nearly twenty countries. The cost of a Halo is between $10 million and $12 million.

   The Halo has the load-carrying capability of a domestic C-130 transport plane. Its cargo area, with the rear ramp closed, is 12 m long, and 3.2 m wide, with a minimum ceiling height of 2.9 m. This cargo area can hold two combat vehicles weighting 9 988kg each. The interior can be configured to seat eighty combat-equipped troops or sixty stretchers. The Halo is flown by a crew of four: pilot, copilot, flight engineer, and navigator. The flight deck and cabin are fully air conditioned, but only the flight deck is pressurized.

   The Halo's landing gear is a noretractable tricycle-type with a steerable nose wheel. The main gear can be hydraulically adjusted to facilitate loading through the rear door. This adjustable feature is also used when landing on varied surfaces. Each of the main gears has a sensor to determine takeoff weight. This information is displayed at the flight engineer's station at liftoff. The Halo's retractable tail skid offers unrestricted accessibility to the rear cargo loading door. There is a hatch on the underside of the fuselage that opens to give access to a load sling. This sling is attached to an internal winch that's in-line with the main rotor shaft. Closed-circuit television cameras enable crew members to monitor the load beneath the aircraft.

   The Halo was the first helicopter to successfully fly with an eight-blade main rotor. This rotor is 32 m in diameter and is made of composites and aluminum alloys, with a leading edge made of titanium. The main rotor head and the tail rotor head are both made of titanium. The flight controls are hydraulically boosted with a redundant autopilot and stability-augmentation system. The enormous Halo is powered by two 10 000-shaft-horsepower ZMKB Progress D-136 turboshaft engines. Each engine bay is made of titanium for protection against fire.

   Several variants of the Mi-26 Halo have been built.

Variants

   Mi-26A upgraded version with improved navigation system;

   Mi-26T is a civil transport version that is essentially the same as the military model. It provides accommodation for 70 passengers;

   Mi-26TP a fire-fighting version that's able to carry 7 500 l of fire retardant, and a geological survey version that is used for towing seismic gear;

   Mi-26P Halo is a transport version that can accommodate sixty-three passengers in airline-type seating. Amenities for the transport include a galley and a restroom;

   Mi-26PP electronic warfare version;

   Mi-26S version for disaster relief tasks, equipped with deactivating liquid tank and underbelly spraying apparatus, used in the 1986 Chernobyl nuclear accident;

   Mi-26TZ is a fuel tanker that can carry 14 000 l of additional fuel. This fuel can be dispensed by four hoses to other aircraft, or by ten hoses to ground vehicles;

   Mi-26MS is a full medical evacuation version. It houses an operating room, pre-op section, laboratory, restroom, scrub facilities, and food storage;

   Mi-26TM is a flying crane. An under-fuselage gondola is large enough for the crane operator and one other person;

   Mi-26M is the latest and most powerful variant. All M-version Halos are equipped with two ZMKB Progress D-127 turboshaft engines. These engines each produce approximately 14 000 shaft horsepower. This additional power increases the maximum payload to 24 970 kg. The additional power provided by these engines also allows maximum payload-carrying ability at high altitude and in warm weather, conditions that are generally detrimental to any helicopter's performance;

   Mi-27 flying command post.