Cold War

17,000: Mi-8 is the Most Produced Helicopter in History

When you think of Soviet aircraft, you probably think of MiGs, the Tu-95, and the Mi-8. The Mi-8 is the most produced helicopter ever – if there is a job that needs doing, a Mi-8 has probably been built to do it.

This machine, known to NATO as the “Hip”, is an iconic piece of Soviet design, having been first drawn up in the 1950s. After dozens of variants and derivatives, the Mi-8 continues in service today in huge numbers, and is still being built.

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Designing a Legend

In the early 1950s helicopters were still a relatively new concept, but had already proven to be extremely valuable. At this time the Soviet Union’s primary helicopter was the Mil Mi-4, which while capable of respectable loads, was still powered by a piston engine and was already outdated against newer designs.

In particular, the Mil Mi-6; a huge, twin-turbojet powered beast that could carry over 60 troops or even armored vehicles. This helicopter was a significant leap forward compared to the Mi-4.

The Mi-6 inspired Mikhail Mil, aerospace engineer and founder of Mil Moscow Helicopter Plant, to design new helicopters for the light and medium range along similar lines to the Mi-6.

A Soviet Mi-6 helicopter.
The Mi-6. It first flew in 1957, and was a staggering 137 ft (42 meters) in length, and weighed 97,000 lbs (44,000 kg) fully loaded. Image by Rob Schleiffert CC BY-SA 2.0.

He suggested this to Soviet leadership in the second half of the 1950s, but due to budget constraints and a lack of perceived importance, they had little interest. Besides, the Mi-4 was doing a good job.

With little chance of ever getting the funding for a brand new airframe, Mil opted to redesign the Mi-4 with two engines, as this had a higher chance of being approved for production. Mil was passionate about having two-engines, as it provided redundancy if an engine failed.

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Eventually the Soviet Ministry of Civil Aviation showed interest, and in 1958 greenlit a project for a new medium-lift helicopter, designated the V-8. The V-8 was based on the Mi-4 but had a heavily modified front end.

Mi-4 gate guard in Russia.
The Mi-4 (NATO codename: Hound). It bore a strong resemblance to the American H-19. Image by Alan Wilson CC BY-SA 2.0.

The engine had been moved to above the cargo bay (on the Mi-4, the engine was located in front of the cockpit), and was now a 1,900 shp turbine, rather than a piston engine.

However many other aspects, such as the rotors, transmission, tail boom etc. were unmodified from the Mi-4. It also still lacked twin engines.

The Soviet military soon became interested, as did Soviet Premier Nikita Khrushchev! After a trip on the US’ presidential helicopter, he wanted something to impress with when hosting the US president. There were plans to make cargo, attack, passenger and VIP variants of the helicopter.

V-8 prototype.
V-8 single engine prototype.

With all this interest, Mil was able to convince leadership that the V-8 should have two engines. Soon, a 1,250 hp turbine engine and a transmission were built specifically for the V-8.

This marked the first time that an engine had been designed specifically for a helicopter – previous designs, like the Mi-4 and Mi-6 used repurposed aircraft engines.

With this, the V-8/Mi-8 would be safer and able to lift more weight.

Nikita Khrushchev in front of the Mi-8 prototype.
Nikita Khrushchev in front of the V-8A twin-engine prototype. It was well-liked instantly.

The construction of a twin-engine prototype (designated V-8A) was approved in 1960. A huge list of other changes were then implemented into the design, such as electronic de-icing systems, tricycle landing gear and artificial-feel through the control sticks – transforming it into a truly modern helicopter.

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The first flight would occur in 1961, although this was of the single-engine V-8. Despite being less-capable, this helicopter impressed both the civil aviation industry and the military; it was reliable, fast, practical and could carry large loads.

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The twin-engine V-8A would fly the following year in 1962, and soon made the V-8 redundant. The V-8A proceeded into testing by the military and civil aviation, and gradually received even more features (autopilot, new tail rotor, to mention a few).

By this point the V-8 was essentially an entirely new airframe, compared to the Mi-4.

The helicopter was tested in various configurations, such as a VIP transport, a cargo hauler, and a passenger carrier. These allowed improvements to be made that better suited the airframe for these roles (cargo tie downs, access points, sound deadening, etc.).

Mi-8 cargo prototype.
The prototype for the transport variant of the Mi-8, known as the V-8AT.

After this extensive testing and development program, the designers had created a helicopter that could lift twice as much as the Mi-4 and fly almost 50 mph faster. It was recommended for production in 1964 as the Mi-8, with the first airframes being completed in 1965.

The Soviet Air Force would accept the Mi-8 into service in 1967.

It came in two major variants, the Mi-8T, the cargo/utility version and the Mi-8P, for passenger transport.

Mi-8 Design Brief

The Mi-8 is twin-engine, single rotor helicopter primarily used as a cargo transport. However, over the six decades it has been in production there have been a vast number of modifications, changes and whole new variants that all have slight-to-major differences.

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At the time of its development, the Mi-8’s most novel feature was its two engines. These were TV2-117 gas turbines, each producing 1,500 shp. They sent their power through a VR-8 main gearbox to a four bladed, 70 ft (21.3 meter) wide rotor blade.

TV3-117 turbine engine.
A TV3-117 turbine engine, used in later examples of the Mi-8. Image by Alf van Beem.

They were mounted side-by-side on top of the cargo hold, and offered a much greater degree of safety should an engine failure occur. The Mi-8 was capable of maintaining level flight while being powered by just one of the TV2-117 engines.

They were fitted with a system that automatically increased the power output of the remaining engine, should one go offline.

A few different variations of the engine were produced. The TV2-117F, for example, could produce 1,700 shp. The TV2-117AG was fitted with graphite seals for a longer service life, and one type, the TV2-117TG, ran on liquid methane.

The cockpit of a Ukrainian Hip.
The spacious cockpit and windscreen give the crew an excellent view. Image by Нацгвардія України CC BY-SA 2.0.

In 1970s the Mi-8 began being fitted with the more powerful TV3-117 turbine, which produce 1,950 shp.

With these engines, the Mi-8 is able to reach a top speed of 160 mph, and climb to 16,000 ft (5,000 meters). Its payload capacity is either 24 passengers, or up to 8,800 lb (4,000 kg) of cargo or weaponry.

It is operated by a crew of three; a pilot, co-pilot/navigator and a flight engineer, who are located three-abreast in the cockpit at the front of the fuselage.

Mi-8 Cargo Bay interior.
The Mi-8’s cargo bay. The seats can be folded up against the fuselage when more room is needed. Image by Nemracc CC BY-SA 4.0.

It is a spacious cockpit with a huge glanced window, giving the crew excellent views from their stations.

As mentioned, there have been many modifications to the Mi-8 over its service life. A derivative of the Mi-8, the Mi-14, was designed as an anti-submarine helicopter for the Soviet Navy.

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Some are equipped for mine clearing or laying, and others are able to conduct electronic warfare missions. There are fuel tanker, reconnaissance, passenger, search and rescue, and VIP transport versions, and many more.

Mi-14 amphibious helicopter in flight.
The Mi-14 is an amphibious derivative of the Mi-8, and has a boat-shaped lower hull for landing on water.

Over time upgrades have been made, especially regarding the Mi-8’s radars and avionics. The engines too have continued to be improved, with changes in the 1980s allowing them to operate at higher altitudes.

The Mi-8’s Service Life

The Mi-8 is a massively successful design, having been in production continuously since the 1960s (and still is today) and built in enormous numbers. Today, the Mi-8 is the most produced helicopter in history, with over 17,000 being built in total.

It has been a major export success too, after the introduction of the Mi-17 export variant in the 1980s. It has been used by over 50 countries, including Germany, Ukraine, Türkiye, Peru, Pakistan, and Bulgaria.

Mi-8 flying over Chernobyl.
Mi-8 flying near the Chernobyl nuclear reactor building in 1986.

Even the United States has a small fleet of Mi-8s, which have been used by special forces. The Soviet Union was of course the largest operator, with the type becoming its primary medium-class helicopter.

In Soviet service these helicopters have been in involved in some high-profile events, like dropping radiation-absorbing materials into the Chernobyl power plant, or engaging in battles during the USSR’s invasion of Afghanistan in the 1980s.

Bosnian Mi-8 parked in Bosnia.
An Mi-8 in Bosnian Muslim Army service during the Bosnian conflict.

There saw heavy use in Iran-Iraq War, also in the 1980s, and during the Bosnian and Kosovo wars in the 1990s.

Today, the Mi-8 is still in large-scale use all over the planet, and is currently back on the world stage as it being prominently used by both Russia during their invasion of Ukraine.

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It will remain in service for years to come, so we certainly haven’t seen the end of the Mi-8’s story.

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