Early Cold War
In 1962, WSK-Swidnik in Poland began producing the Mi-2 Hoplite under license, although the plant did not reach full production until 1965. With two Isotov GTD-350 turboshafts mounted above the cabin, the Mi-2 produced 40 percent more power, at less than half the weight, effectively doubling the lifting capability of the Mi-1. An all-metal three-bladed rotor system, measuring 47 feet, 9 inches in diameter, provided lift for the single-pilot, eight-passenger utility helicopter. Of a modified pod and boom design, the Mi-2 attained a maximum airspeed of 110 knots and hauled 3,000 pounds of internal cargo, or a 1,750-pound slingload. External pylons provided mounting points for a combination of machine guns and AT-2 Sagger ATGMs. The Mil Company reported the maximum service ceiling at 13,000 feet.
In the late 1950s, to meet several requirements of the Soviet military, Mikhail Leontyevich Mil began designing and producing large heavy-lift helicopters. On June 5, 1957, Mil Design Bureau test pilot Rafail Kaprelian piloted the Mi-6 Hook on its maiden flight. The first of five prototypes, the Mi-6 was the world’s largest helicopter to that time, and the Soviet Union’s first production turbine-powered helicopter. The fuselage measured 134.5 feet, and the five-bladed, all-metal main rotor system 114.8 feet in diameter, dwarfing all previous helicopters. Two removable wings, with a span of 50 feet, 2 inches, provided additional lift in forward flight. The groundcrew usually removed the wings for large slingload operations, as they just increased drag.
Mil utilized plastic-impregnated wood, reinforced with steel spars, to manufacture the four-bladed tailrotor. Production models carried an alcohol-based deicing system. Equipped with two Soloviev D-25V turbine engines, producing 5,500 horsepower each, the huge machine could carry up to ninety troops and lift off at a maximum gross weight of 93,500 pounds, which translated into a payload of 26,400 pounds of internal cargo, or a 17,500-pound slingload. As an air ambulance the Hook could accommodate forty-one stretchers and two medical attendants. Two hydraulically operated rear-opening clamshell doors made possible the loading of large cargo into the fuselage, which included a winch with a capacity of 1,750 pounds. A pilot, copilot, navigator, flight engineer, and radio operator composed the crew. In 1961 the Mi-6 became not only the largest but also the fastest helicopter in the world by reaching 300 kph (162 knots), thereby winning the Igor Sikorsky International trophy. The Hook had a range of 385 statute miles and a service ceiling of 14,750 feet. For ferry flights the Mi-6 could carry four auxiliary fuel tanks, two installed internally and two mounted above the main wheels of the fixed tricycle landing gear.
The standard avionics package provided the Hook with day/night, all-weather capabilities. The helicopter usually carried a ground power unit (GPU) on a trolley for engine starting and ground operations. A single DShK 12.7-mm heavy machine gun could be installed in a flex mount in the nose for self-protection. From the time the Mi-6 entered production in late 1960, until production ended in 1981, Mil produced 860 aircraft. Aeroflot used the large helicopters in trackless Siberia, while the Soviet military utilized the heavy-lift capabilities of the machine to transport rocket launchers and other heavy weapons. The Mi-6VKP, Hook “B,” hauled a huge array of radios and functioned as an airborne command post, which eventually led to the Mi-22C “command post.” The Hook, in various modifications, provided forward refueling points for both vehicles and aircraft, fought forest fires, and recovered Soyuz space capsules. The USSR produced 860 Hooks and exported the machine to several countries, including North Vietnam, which used the Hook to carry fighter aircraft from airfields to remote locations to protect the jets from U. S. air strikes. In July 2002 an Mi-6 crashed, killing all twenty-one on board, and the Russian Ministry of Transportation halted the use of the aging Mi-6.
Continuing to focus on heavy-lift helicopters, the Mil Bureau introduced the Mi-10 Harke. In July 1961 the “flying crane” modification of the Mi-6 appeared at the Soviet Tushino Air Show; it flew at the Paris Air Show in 1965. The Mi-10 shared engines, transmissions, rotor system, hydraulics, and many other parts with the Mi-6, reducing maintenance costs for both aircraft. The Mi-10, however, featured a much modified fuselage designed for transporting large external loads weighing up to 36,300 pounds. Mil designed the machine with an extended, wide, four-legged dual-wheeled landing gear to straddle large, cumbersome loads. For whatever reason, the bureau fitted the aircraft with right-side struts a foot shorter than those on the left, causing the machine to cant slightly to the right when parked.
Several other modifications differentiated the Harke from the Hook. Hydraulic arms fitted to the fuselage underside held specially designed wheeled pallets in place during flight. It was intended primarily as a cargo helicopter, and there were no provisions to install removable wings; the shortened, 107-foot, 10-inch fuselage, however, could accommodate up to twenty-eight passengers in addition to the three-man crew. The first models included a pod, or “dustbin,” under the nose by which the crew could observe external loads, but the pod was removed from later models and the crew monitored their loads via closed-circuit television. Slower than the Hook, the Mi-10 reached a top speed of 120 knots and a service ceiling of 9,850 feet.
The Mi-10K variant appeared in 1966. Differing slightly from previous models, the “K” offered greater lift capacity, shorter landing gear struts, and a gondola under the forward fuselage. The gondola, reflecting that on the Sikorsky CH-54, housed a full set of flight controls, allowing a copilot to position unwieldy payloads accurately. Certain specialized variants included the Mi-10P electronic countermeasures (ECM) helicopter. The Soviet Union produced only fifty-five Mi-10s, and none are known to have been exported.
In 1965 the Mil bureau began work on the largest helicopter ever built, the Mi-12 Homer. Designated the V-12 by the Soviets, the aircraft, comparable in size to a Boeing 727, first took flight in 1968. The next year a prototype lifted a 72,000-pound payload to 7,900 feet, setting a new weight-to-altitude record. Capable of carrying 120 passengers, the Homer made its first public appearance at the 1971 Paris Air Show.
Designed by Mil, who died in 1972 and was replaced by Marat Tischenko, the Mi-12 encountered numerous developmental problems. Of a side-by-side rotor design, the Homer incorporated the engines and transmissions of the Mi-6. At the end of two reverse-tapered wings (wider at the tip than at the root), two Soloviev 5,500-horsepower turboshafts drove a five-bladed rotor system. The Mi-12 sat on a dual-wheeled tricycle landing gear, and large clamshell doors at the rear of the fuselage allowed loading of oversize cargo. Requiring a crew of six, the Homer never fully met its design specifications, and the program was canceled. One prototype remains on static display in Russia.
In May 1960, Mil conceived a machine to replace the piston-engined Mi-4 Hound. On June 9, 1961, the first Mi-8 Hip prototype, with a single AI-24V turboshaft and four-bladed main rotor system, lifted off for its maiden flight. On September 17, 1962, the Hip B, modified with two TV2-117 1,482-horsepower turboshafts mounted atop the fuselage, and a five-bladed main rotor system measuring 70 feet in diameter, took flight. The Mi-8 went into full production in 1965, and by 2000 fifty-four countries operated the more than 10,000 Mi-8s manufactured by the Rostov and Kazan production facilities in Russia and by foreign licensees. Designed as a medium-lift transport helicopter, the Hip, in its many variants, fulfilled a miscellany of mission requirements, including troop and cargo transportation, air ambulance, attack helicopter, airborne command post, fire fighter, and civilian carrier.
Constructed of light alloys, the Hip featured a “bus-shaped” fuselage with a rounded nose and glassed-in cockpit that accommodated a pilot, copilot, and flight engineer. The cabin housed twenty-four passengers, 8,800 pounds of cargo, or twelve stretchers. A large sliding door on the forward port side and rear-opening clamshell doors simplified loading large cargo. Removable interior seats and an internal winch capable of lifting 350 pounds that doubled as a rescue hoist facilitated cargo handling. Additionally, Mil equipped the aircraft with a cargo hook capable of carrying slingloads up to 6,500 pounds. A long tailboom extended from the upper portion of the fuselage and swept up to a tapered vertical fin that housed the gearbox and tailrotor, attached to the left side (right on the export versions).
External racks attached along the center of the 61-foot fuselage were designed to hold auxiliary fuel pods or weapons systems. Variants of the Hip carried a combination of 57-mm or 80-mm rockets, AT-2 Swatter or AT-3 Sagger ATGMs, 12.7- or 23-mm gun pods, or either 4 500-pound or 2 1,000-pound bombs. In 1967, Mil introduced the Hip E and F ground support helicopters, each mounting a flexible 12.7-mm heavy machine gun under the nose and carrying 192 57-mm rockets. Combat troops could also fire their individual weapons from the windows of the helicopter. In later models Mil installed the upgraded Isotov TV2-117A engines, which produced 1,700 horsepower each. Generally a Hip cruised at 122 knots, had a service ceiling of 14,700 feet, and hovered Out of Ground Effect (OGE) at 2,600 feet. All Mi-8s rested on a fixed tricycle landing gear, with dual wheels at the nose. Total production estimates ran as high as 15,000 units of the Mi-8 and its export version, the Mi-17.
In September 1969 the Mil Design Bureau modified the Hip into the Mi-14 Haze for naval applications, mainly for shore-based ASW operations. The Mi-14 received a boat-hulled lower fuselage with pontoons on either side and a retractable landing gear. A radar dome under the nose and an internal weapons bay differentiated the Mi- 14 from the Mi-8. Both the Mi-8 and Mi-14 carried infrared jammers and flare/chaff dispensers.
Another modification allowed the TV2-117TG engines to operate on both liquefied petroleum gas (LPG) and standard jet fuel (a type of kerosene). Large external tanks held the LPG under low pressure, and the pilots switched the engines to regular fuel for takeoffs and landings. The LPG tanks reduced the helicopter’s payload by 220 to 330 pounds but extended its useful range by several miles.
In July 1961 the Kamov Ka-20 Harp appeared for the first time during the Soviet Aviation Day celebration. The Ka-20 followed the traditional N. I. Kamov coaxial rotor design, with two three-bladed, counter-rotating main rotors. A large bulge under the forward fuselage and a fairing under the tailboom indicated that the Ka-20 was an ASW helicopter of some type. It was much larger than the Ka-18, with dual turbine engines mounted over the cabin body. Two fixed machine guns protruded from the nose, and two air to surface missiles (ASM), probably dummies, hung from external racks on each side of the helicopter. The new craft proved to be an advanced prototype of the Ka-25 Hormone, which became operational with the Soviet Navy in 1965.
Only slightly different from its predecessor, the Kamov Bureau (OKB) produced the Ka-25 Hormone in three major variants, all powered by two Glushenko GTD-3 900-horsepower turboshafts, as well as featuring a coaxial rotor system and the compact body most effective in shipboard operations. OKB designers included folding main rotor blades, reducing the Ka-25’s stowed length to only 36 feet. The Hormone A, designed specifically to destroy nuclear-powered submarines, carried two pilots and three sensor technicians to operate ASW equipment, which included a search radar installed in a large, chin-mounted radome, a towed magnetic anomaly detector (MAD), and a dipping sonar housed in a compartment at the rear of the cabin. Some models featured ventral weapons bays by which the Ka-25 could be armed with torpedoes, depth charges (including nuclear), or air to surface missiles. Later improvements to the Hormone included an automatic pilot, state-of-the-art avionics, and a vastly improved over-the-water navigation system for precise targeting of submarines and surface vessels. By 1968 the Hormone A operated from cruisers of the Kresta and Kara classes, Moskva and Leningrad carrier/cruisers, and Kiev and Minsk ASW carriers. The smaller cruisers carried only two Ka-25s, while as many as eighteen Hormones operated off the larger ASW carriers.
The second variant carried search radar and other electro-optic target acquisition equipment for over-the-horizon guidance of surface-to-surface missiles and naval rifles. A larger, and more spherical, chin radome, a cylindrical radome mounted at the aft end of the fuselage, and no ventral bays differentiated the Ka-25 B from other models. The Hormone reached an airspeed of 105 knots, a range of 350 nautical miles, and a service ceiling of 11,000 feet.
In a later variant, the Hormone C, OKB engineers removed the ASW and targeting instrumentation and equipped the helicopter for SAR missions. Without the electronic gear the large cabin also offered a secondary capability of transporting twelve naval infantry troops. Two other versions appeared in limited numbers, the Ka-25 BT mine countermeasures helicopter and the Ka-25 K civilian helicopter, which had a small cockpit under the forward fuselage for slingload operations. In the event of ditching, most models of the Hormone were fitted with inflatable pontoons on each of the four landing gear struts. Between 1965 and 1975 the USSR produced more than 460 Ka-25s, with export models sent to Syria, India, Bulgaria, North Vietnam, and Yugoslavia.
In January 1964 the Soviet government issued a directive for both an agricultural and a passenger transport helicopter. On August 18 of the next year, the Kamov Bureau responded with the prototype Ka-26 Hoodlum, a small, multipurpose helicopter. Kamov deputy chief designer M. A. Kupfer and project leading engineer Y. I. Petrukhin, of course, specified the installation of OKB’s typical coaxial rotor system atop the boxlike fuselage of the Ka-26. The craft incorporated a conventional Kamov tail assembly of twin vertical fins with rudders and an interconnecting horizontal stabilizer, which included the elevator. The helicopter sat on a four-wheeled fixed landing gear. Initial manufacture began in 1967 at the Kumertau Aircraft Plant. Placed in full production in 1970, the multirole helicopter was powered by two 325-horsepower Vedeneyev M-14V- 26 nine-cylinder radial engines. Flown by either one or two pilots, the Hoodlum hauled loads of 2,000 pounds up to altitudes of 9,850 feet, at speeds of 95 knots. OKB’s modular design and interchangeable cargo containers permitted rapid conversion of the Hoodlum from a passenger carrier to an air ambulance, crop duster, or “flying crane.” Kamov OKB first used composite materials for the engine cowlings, rotor blades, and chemical hoppers, which increased the useful life of Ka-26 subassemblies. The composite rotor blades, for example, demonstrated a service life of 5,000 hours, compared with the 600 to 800 hours of conventional metal blades of the era. With OKB production methods patented in five Western nations, the Hoodlum became the only Soviet helicopter certificated under U. S. federal aviation regulations (FAR). The Soviet Union produced at least 850 Ka-26s and exported the machine worldwide.
In 1970, Kamov created his first designs for the next generation of Soviet naval helicopters. He envisioned a machine similar in size to the Ka-25 but with an updated avionics and weapons package. On December 24, 1973, OKB’s chief pilot, Y. I. Laryushin, lifted the prototype Ka-252 off for its first flight. Unfortunately, the aircraft’s designer did not see his project completed; Kamov died on November 24. Sergei Viktorovich Mikheyev then assumed the directorship of OKB, which in 1974 was renamed in honor of Nikolai Il’yich Kamov.
Developed from the Ka-252 prototype, the Ka-27 Helix produced more power from the two Isotov TV3-117 2,225-horsepower turboshafts mounted under the three-bladed coaxial rotor system. Only slightly longer than the Ka-25, the Helix had a redesigned tail assembly. With a maximum gross weight of 24,250 pounds, the Ka-27 rotor diameter measured 52 feet, 2 inches and the aircraft 37 feet, 1 inch in length. Capable of 140 knots, the Helix had a maximum range of 432 nautical miles and a service ceiling of 19,700 feet. Designed specifically for the Soviet Navy as an ASW hunter/killer, the Helix did not become operational until 1978.