--- title: "Mil V-12: The Largest Helicopter Ever Built" description: "There are some jobs in this world that were just made for the Soviet Union to excel at: being a high-quality arch-nemesis to the United States, chucking things into space, building a massive stockpile of nuclear weapons, cooking some absolutely bangin' borscht, and perhaps most of all, churning up ideas for new and deadly superweapons. From the T-42 super-heavy tank to the Fractional Orbital Bombardment System to the handheld laser pistol, the Soviets were masters at drawing up weapons systems that could send the West into a panic, while reassuring the Party that its best days were still ahead.\n\nSpeaking of which, it's time we talk about the Mil V-12. At a length of 37 meters, a span of 67 meters from rotor tip to rotor tip, and a maximum takeoff weight of over a hundred thousand kilograms, it still holds the record as the largest helicopter the world has ever seen. When the V-12 burst onto the international scene in 1971, it had NATO quaking in its boots — but within just three years, the project had been condemned in full to the Soviet trash heap.\n\nThis is the story of the groundbreaking design of the Mil V-12, and the accumulation of roadblocks and hurdles that kept the chopper firmly on the ground forever.\n\n## A Nuclear Logistics Problem\n\nThe origins of the V-12, like the origins of most Cold-War-era engineering advancements, were ultimately about nuclear weapons. The Soviet Union had no shortage of nuclear warheads, nor of the intercontinental ballistic missiles — ICBMs — that would fire them. What it had was a logistical problem: how to get those ICBMs to a launchpad without the Americans finding them.\n\nFor a nuclear-armed nation, it is vital to keep the location of ready-to-launch weapons either secret or extremely well-protected. The logic of deterrence is delicate. If Nation A wants to launch its nuclear weapons at Nation B, but Nation B has its own hidden weapons aimed back at Nation A, then there probably won't be a nuclear exchange — both sides risk destruction by launching. But if Nation A knows where Nation B hides its missiles, Nation A can bomb those sites first, taking out Nation B's ability to retaliate, and with it, Nation B's best hope of convincing Nation A not to attack in the first place.\n\nBecause of that fine balance, both superpowers spent the Cold War hard at work trying to identify each other's launch sites while keeping their own hidden. In hindsight, neither side was especially enthusiastic about launching a full-scale assault just because it could — but each wanted the security of knowing it could end a conflict decisively if a launch from the other side appeared imminent. For the Soviets, that meant constantly dealing with American U-2 spy planes trying to build a full inventory of where Soviet missiles were located.\n\n## Why a Helicopter, of All Things\n\nThe annoying thing about ICBMs, particularly the earlier variants, is how much of a pain they are to transport. This was a problem for the Soviets in particular, because many of the strategic launch sites that could fire ICBMs over the Arctic toward the continental US were extremely remote. With no roads or landing strips in those areas, the only way to actually get an ICBM to the necessary location was by train — but those train tracks would draw a line right to the launch sites.\n\nSoviet infrastructure did not rely heavily on rail transport in general, so any new railroad an American U-2 observed would stick out like a sore thumb and lead directly to a launch facility. A new road or airstrip large enough to move ICBMs wouldn't be much better.\n\nA helipad, on the other hand, could be concealed far more easily, since any vertical-takeoff-and-landing aircraft needs far less space to touch down. If a Soviet helicopter existed that was large enough to carry an ICBM, it could solve the transport problem and help uphold the international order of Mutually Assured Destruction.\n\nFor Party leadership, there was one place to go for this kind of technology: the Mil Design Bureau of the Moscow Helicopter Plant, headquartered in the town of Tomilino, Russia. Mil had already entrenched itself as the Soviet go-to for all things helicopters, and had just introduced the Mi-6 — both the world's largest helicopter at the time and a successful one during its years supporting the Soviet armed forces. The Mi-6 had broken a string of world records when it entered service, and the new helicopter would need to break them all over again.\n\n## Designing a Giant\n\nMil's new design would have to lift some 20 to 25 tons of payload, plus its own mass, on long-haul flights across the Soviet Union. That was enough capacity to hold three kinds of ICBM — or, just as usefully, a large amount of conventional weaponry and supplies. But balancing that kind of weight in the long, tube-like shape of a missile would be impossible in a helicopter with a single top rotor. Helicopters are hard to keep stable at the best of times, and a hundred-foot-long craft really shouldn't rely on one little tail rotor. A single rotor also wouldn't generate enough lift to get the thing off the ground in the first place.\n\nThe Soviets explored a tandem-rotor system, like the one the United States used on its Chinook helicopters, but these had their own problems, and eventually the engineers gave up on the idea. The concept they settled on instead was a so-called transverse layout: two equal-size rotors mounted at the ends of support wings, which were believed to give enough stability for the helicopter to at least maintain safe flight. The modern Bell-Boeing V-22 Osprey uses this same basic concept.\n\nThe Mil design would have a massive rotor span — almost 220 feet, or 67 meters, from tip to tip. Powered by four D-25 engines of 6,500 horsepower each, the design blew Soviet expectations out of the water on carrying capacity: in addition to its own weight, this absolute unit could get some forty or more tons off the ground.\n\nThe rest of the helicopter took shape around those two transverse rotors. The freight compartment was 28 meters long, and four and a half meters tall and wide — more than large enough to hold a city bus, with a carrying capacity of 196 passengers. That meant just two of the helicopters could conceivably carry an entire Soviet battalion into battle. The chopper was crewed by six operators: a pilot, a copilot, a flight engineer, a navigator, a radio operator, and a dedicated electrician. It used a two-cockpit design, with the navigator and radio operator in the upper section and everyone else down below. The back end opened up with two massive clamshell-style doors, and it was fitted to carry payloads slung underneath as well, in case something couldn't fit inside. The V-12, as it would eventually be dubbed, could hit a top speed of 260 kilometers per hour, with a range of 500 kilometers — or double that, if it only had to make a one-way trip.\n\n## A Rocky First Flight, Then Records\n\nThe first prototype of the V-12 was finished in 1968, eight years after the design was produced. Its first test flight, just a few months prior, had not gone well at all. As the pilots found out the hard way, the helicopter had a tendency to shake so hard that everyone on board risked losing their lunch — and risked in-flight accidents, like involuntary rolls. That is precisely what happened. The first test flight ended with the V-12 smashing into the ground and popping its own tires.\n\nOn its own, that might not have been much of a problem; tires come cheap when you've got the R&D budget of a global superpower. But the government had gotten ahead of itself hyping up the new super-copter for Western audiences, and a relatively minor accident turned into a major black eye.\n\nAfter a year of repairs and modifications, the newer, better V-12 was ready to fly again, this time with a lot less fanfare. The chopper successfully flew from its pad at the Mil factory to a testing facility, and once it could be trusted to get off the ground, it started to blow even its own operators away with how much it could handle. Before long, the V-12 had broken eight world records for lifting massive amounts of cargo and getting them above certain altitudes. In fact, it still holds four of those records today.\n\nThe prototype, and a second helicopter delivered shortly afterward, were lauded around the world — including being awarded the prestigious Sikorsky Prize by the American Helicopter Society — and the design was patented internationally. The memories of that first flight were all but erased. The V-12 became such a press victory for the Soviet Union that even the US and its allies couldn't help but applaud. Western militaries flew into a panic trying to figure out what the V-12 was for, and how the Soviets had managed to build a helicopter so damn big, and the Soviet government wasn't shy about showing it off. Its crowning moment came at the Paris Air Show in 1971 — and since there was no way to get the V-12 there unless it flew itself, the Soviets took full advantage with an air tour over several major European cities.\n\n## Outpaced by the Satellite\n\nWe still don't actually know just how much the Soviet Union spent to put the V-12 in the skies. But whatever the final figure was, it wasn't going to be worth it just because the helicopter had given some American generals nightmares. The helicopter was built to fly, and fly it would.\n\nExcept, well, fly it wouldn't. The Soviet leadership didn't tell the world, but privately they had realized the V-12 design was doomed even before they received the second prototype. The reason was simple: those pesky U-2 spy planes were no longer the only eyes in the sky the Soviets had to contend with. The era of spy satellites had begun. While individual planes could only photograph fairly small patches of land on each flight, satellites could image millions of square miles at a time and beam that data straight back to the United States. The days of scattershot intelligence flights had passed, and missile-launch sites could no longer be hidden just by putting them in the middle of nowhere. Even if the Americans had previously thought those areas too low-priority to examine, the satellites could now examine them with no problem.\n\nOf course, this advancement worked both ways — the Americans could see the Soviet launch sites, and the Soviets could see the American ones. But the V-12 quickly became one of satellite technology's confirmed kills, because there was no longer any need to haul ICBMs around by air.\n\nAnd the helicopter didn't serve much practical use anywhere else either. In a war zone, sure, carrying some 200 troops inside sounded pretty cool — but shoot down one V-12, and the enemy takes out half a Soviet battalion in one strike. The same went for cargo. And if cargo had to be airlifted for non-combat purposes, well, why not just use a plane? The situations in which a V-12's vertical-takeoff capability was truly needed — for an amount of cargo that couldn't just be split between multiple smaller helicopters — were extremely limited, and they certainly didn't justify the cost.\n\n## The Greatest Helicopter That Never Was\n\nThe Soviet Air Force outright refused to accept the helicopter design for trials. The Mil Design Bureau continued to work on the project for a little while, but the entire thing was mothballed by 1974. Of the two prototypes built, one was kept at Mil's helicopter plant, while the other was donated to an Air Force museum near Moscow to be displayed to the public. An anticipated second version of the craft, meant to carry even heavier loads, was also cancelled. Mil briefly entertained the idea of a variant for commercial use in Siberia, but again, there just wasn't a need for a helicopter of the V-12's size.\n\nIf there's any small victory the V-12 achieved, it might have been getting the Americans to waste some of their own R&D budget trying to build a competitor aircraft — but that's just about all the helicopter ultimately accomplished.\n\nToday, the V-12 lives on exclusively through the records it set and the prototypes that continue to capture the public's imagination. It's a testament both to the V-12's incredible feats of engineering and to its obsolescence that many of its records stay unbeaten today, with no known aircraft currently in development that would even come close to its lifting capacity. It will probably hold those records for a very long time. Its successor craft — most prominently the Mil Mi-26 — have given the V-12 no reason to step back out of retirement. In all likelihood, the V-12 will remain the world's greatest helicopter that never was.\n\n## Key Takeaways\n\n- The Mil V-12 remains the largest helicopter ever built, at 37 meters long with a 67-meter rotor span and a maximum takeoff weight of over 100,000 kilograms.\n- It was conceived to airlift ICBMs to remote launch sites without leaving the telltale roads, rail lines, or airstrips that American U-2 spy planes could spot.\n- Rather than a single or tandem rotor, the V-12 used a transverse layout — two equal-size rotors on support wings, the same basic concept later used by the V-22 Osprey.\n- Its first test flight ended in a crash from violent shaking and an involuntary roll, but after a year of fixes it broke eight world records and won the Sikorsky Prize.\n- Spy satellites made the missile-airlift mission obsolete before the second prototype even arrived, and the project was mothballed by 1974 with just two aircraft built.\n- The V-12 still holds four of its world records, and its successor, the Mil Mi-26, made any revival unnecessary.\n\n## Frequently Asked Questions\n\n### Why did the Soviet Union build the Mil V-12?\n\nThe V-12 was designed to solve a nuclear logistics problem: moving intercontinental ballistic missiles to remote launch sites without giving away their location. New roads, airstrips, or rail lines would be visible to American U-2 spy planes, but a concealable helipad and a helicopter big enough to carry an ICBM could keep those sites hidden.\n\n### How big was the Mil V-12?\n\nThe V-12 was 37 meters long with a rotor span of 67 meters — almost 220 feet — from tip to tip, and a maximum takeoff weight of over 100,000 kilograms. Its freight compartment was 28 meters long and about four and a half meters tall and wide, large enough to hold a city bus and rated to carry 196 passengers.\n\n### What made the V-12's design unusual?\n\nInstead of a single top rotor or a tandem layout like the American Chinook, the V-12 used a transverse layout, with two equal-size rotors mounted on the ends of support wings for stability. It was powered by four D-25 engines of 6,500 horsepower each, and the same transverse concept later appeared on the Bell-Boeing V-22 Osprey.\n\n### Did the Mil V-12 ever crash?\n\nYes. Its first test flight went badly, with the helicopter shaking so violently that it caused an involuntary roll and ended up smashing into the ground and popping its own tires. After a year of repairs and modifications, the rebuilt V-12 flew successfully and went on to break eight world records.\n\n### Why was the V-12 cancelled?\n\nThe arrival of spy satellites made the missile-airlift mission obsolete, since launch sites could no longer be hidden simply by being remote. The helicopter also had little other practical use, the Soviet Air Force refused to accept it for trials, and the project was mothballed by 1974 with only two prototypes built.\n\n### Does the Mil V-12 still hold any records?\n\nYes. The V-12 broke eight world records for lifting heavy cargo to altitude, and it still holds four of them today. With no known aircraft in development that would come close to its lifting capacity, it is likely to keep those records for a long time.\n\n## Sources\n\n- [Original MegaProjects video: The Mil V-12: The Largest Helicopter Ever Built](https://www.youtube.com/watch?v=676dbUox9ZU)\n- [Encyclopaedia Britannica — Mil Mi-12](https://www.britannica.com/technology/Mil-Mi-12)\n- [AeroTime — The largest helicopter ever built: Mil V-12](https://www.aerotime.aero/articles/26072-the-largest-helicopter-ever-built-mil-v-12)\n- [Aviastar — Mil Mi-12 (V-12)](http://www.aviastar.org/helicopters_eng/mi-12.php)\n\n- [Hero image source](https://commons.wikimedia.org/wiki/File:Mil_V-12_Mi-12_(8912725374).jpg) by Clemens Vasters / Wikimedia Commons, CC BY 2.0.\n\n## Related Coverage\n\n- [The Lockheed U-2: Spying Before Satellites](/article/lockheed-u-2-spy-plane-spying-before-satellites)\n\n- [The Duga Radar The Secret Spying Soviet Radar Next To Chernobyl](/article/the-duga-radar-the-secret-spying-soviet-radar-next-to-chernobyl)\n\n- [The Convair B-36 Peacemaker: The Absolute Unit That Carried America Into the Cold War](/article/convair-b-36-peacemaker-cold-war-bomber)" url: https://megaprojects.pub/article/mil-v-12-largest-helicopter-ever-built.md canonical: https://megaprojects.pub/article/mil-v-12-largest-helicopter-ever-built datePublished: 2026-06-09 dateModified: 2026-06-09 author: - name: Simon Whistler url: https://megaprojects.pub/author/simon-whistler publisher: MegaProjects image: https://media.megaprojects.pub/articles/676dbUox9ZU/hero.jpg type: Article contentHash: a8eb4b66afe5c7642a0fd255686e852e1d212bb5a5136bb6067cd7d3c40fa52d tokens: 4189 summaryUrl: https://megaprojects.pub/article/mil-v-12-largest-helicopter-ever-built.md.summary.md --- There are some jobs in this world that were just made for the Soviet Union to excel at: being a high-quality arch-nemesis to the United States, chucking things into space, building a massive stockpile of nuclear weapons, cooking some absolutely bangin' borscht, and perhaps most of all, churning up ideas for new and deadly superweapons. From the T-42 super-heavy tank to the Fractional Orbital Bombardment System to the handheld laser pistol, the Soviets were masters at drawing up weapons systems that could send the West into a panic, while reassuring the Party that its best days were still ahead. Speaking of which, it's time we talk about the Mil V-12. At a length of 37 meters, a span of 67 meters from rotor tip to rotor tip, and a maximum takeoff weight of over a hundred thousand kilograms, it still holds the record as the largest helicopter the world has ever seen. When the V-12 burst onto the international scene in 1971, it had NATO quaking in its boots — but within just three years, the project had been condemned in full to the Soviet trash heap. This is the story of the groundbreaking design of the Mil V-12, and the accumulation of roadblocks and hurdles that kept the chopper firmly on the ground forever. ## A Nuclear Logistics Problem The origins of the V-12, like the origins of most Cold-War-era engineering advancements, were ultimately about nuclear weapons. The Soviet Union had no shortage of nuclear warheads, nor of the intercontinental ballistic missiles — ICBMs — that would fire them. What it had was a logistical problem: how to get those ICBMs to a launchpad without the Americans finding them. For a nuclear-armed nation, it is vital to keep the location of ready-to-launch weapons either secret or extremely well-protected. The logic of deterrence is delicate. If Nation A wants to launch its nuclear weapons at Nation B, but Nation B has its own hidden weapons aimed back at Nation A, then there probably won't be a nuclear exchange — both sides risk destruction by launching. But if Nation A knows where Nation B hides its missiles, Nation A can bomb those sites first, taking out Nation B's ability to retaliate, and with it, Nation B's best hope of convincing Nation A not to attack in the first place. Because of that fine balance, both superpowers spent the Cold War hard at work trying to identify each other's launch sites while keeping their own hidden. In hindsight, neither side was especially enthusiastic about launching a full-scale assault just because it could — but each wanted the security of knowing it could end a conflict decisively if a launch from the other side appeared imminent. For the Soviets, that meant constantly dealing with American U-2 spy planes trying to build a full inventory of where Soviet missiles were located. ## Why a Helicopter, of All Things The annoying thing about ICBMs, particularly the earlier variants, is how much of a pain they are to transport. This was a problem for the Soviets in particular, because many of the strategic launch sites that could fire ICBMs over the Arctic toward the continental US were extremely remote. With no roads or landing strips in those areas, the only way to actually get an ICBM to the necessary location was by train — but those train tracks would draw a line right to the launch sites. Soviet infrastructure did not rely heavily on rail transport in general, so any new railroad an American U-2 observed would stick out like a sore thumb and lead directly to a launch facility. A new road or airstrip large enough to move ICBMs wouldn't be much better. A helipad, on the other hand, could be concealed far more easily, since any vertical-takeoff-and-landing aircraft needs far less space to touch down. If a Soviet helicopter existed that was large enough to carry an ICBM, it could solve the transport problem and help uphold the international order of Mutually Assured Destruction. For Party leadership, there was one place to go for this kind of technology: the Mil Design Bureau of the Moscow Helicopter Plant, headquartered in the town of Tomilino, Russia. Mil had already entrenched itself as the Soviet go-to for all things helicopters, and had just introduced the Mi-6 — both the world's largest helicopter at the time and a successful one during its years supporting the Soviet armed forces. The Mi-6 had broken a string of world records when it entered service, and the new helicopter would need to break them all over again. ## Designing a Giant Mil's new design would have to lift some 20 to 25 tons of payload, plus its own mass, on long-haul flights across the Soviet Union. That was enough capacity to hold three kinds of ICBM — or, just as usefully, a large amount of conventional weaponry and supplies. But balancing that kind of weight in the long, tube-like shape of a missile would be impossible in a helicopter with a single top rotor. Helicopters are hard to keep stable at the best of times, and a hundred-foot-long craft really shouldn't rely on one little tail rotor. A single rotor also wouldn't generate enough lift to get the thing off the ground in the first place. The Soviets explored a tandem-rotor system, like the one the United States used on its Chinook helicopters, but these had their own problems, and eventually the engineers gave up on the idea. The concept they settled on instead was a so-called transverse layout: two equal-size rotors mounted at the ends of support wings, which were believed to give enough stability for the helicopter to at least maintain safe flight. The modern Bell-Boeing V-22 Osprey uses this same basic concept. The Mil design would have a massive rotor span — almost 220 feet, or 67 meters, from tip to tip. Powered by four D-25 engines of 6,500 horsepower each, the design blew Soviet expectations out of the water on carrying capacity: in addition to its own weight, this absolute unit could get some forty or more tons off the ground. The rest of the helicopter took shape around those two transverse rotors. The freight compartment was 28 meters long, and four and a half meters tall and wide — more than large enough to hold a city bus, with a carrying capacity of 196 passengers. That meant just two of the helicopters could conceivably carry an entire Soviet battalion into battle. The chopper was crewed by six operators: a pilot, a copilot, a flight engineer, a navigator, a radio operator, and a dedicated electrician. It used a two-cockpit design, with the navigator and radio operator in the upper section and everyone else down below. The back end opened up with two massive clamshell-style doors, and it was fitted to carry payloads slung underneath as well, in case something couldn't fit inside. The V-12, as it would eventually be dubbed, could hit a top speed of 260 kilometers per hour, with a range of 500 kilometers — or double that, if it only had to make a one-way trip. ## A Rocky First Flight, Then Records The first prototype of the V-12 was finished in 1968, eight years after the design was produced. Its first test flight, just a few months prior, had not gone well at all. As the pilots found out the hard way, the helicopter had a tendency to shake so hard that everyone on board risked losing their lunch — and risked in-flight accidents, like involuntary rolls. That is precisely what happened. The first test flight ended with the V-12 smashing into the ground and popping its own tires. On its own, that might not have been much of a problem; tires come cheap when you've got the R&D budget of a global superpower. But the government had gotten ahead of itself hyping up the new super-copter for Western audiences, and a relatively minor accident turned into a major black eye. After a year of repairs and modifications, the newer, better V-12 was ready to fly again, this time with a lot less fanfare. The chopper successfully flew from its pad at the Mil factory to a testing facility, and once it could be trusted to get off the ground, it started to blow even its own operators away with how much it could handle. Before long, the V-12 had broken eight world records for lifting massive amounts of cargo and getting them above certain altitudes. In fact, it still holds four of those records today. The prototype, and a second helicopter delivered shortly afterward, were lauded around the world — including being awarded the prestigious Sikorsky Prize by the American Helicopter Society — and the design was patented internationally. The memories of that first flight were all but erased. The V-12 became such a press victory for the Soviet Union that even the US and its allies couldn't help but applaud. Western militaries flew into a panic trying to figure out what the V-12 was for, and how the Soviets had managed to build a helicopter so damn big, and the Soviet government wasn't shy about showing it off. Its crowning moment came at the Paris Air Show in 1971 — and since there was no way to get the V-12 there unless it flew itself, the Soviets took full advantage with an air tour over several major European cities. ## Outpaced by the Satellite We still don't actually know just how much the Soviet Union spent to put the V-12 in the skies. But whatever the final figure was, it wasn't going to be worth it just because the helicopter had given some American generals nightmares. The helicopter was built to fly, and fly it would. Except, well, fly it wouldn't. The Soviet leadership didn't tell the world, but privately they had realized the V-12 design was doomed even before they received the second prototype. The reason was simple: those pesky U-2 spy planes were no longer the only eyes in the sky the Soviets had to contend with. The era of spy satellites had begun. While individual planes could only photograph fairly small patches of land on each flight, satellites could image millions of square miles at a time and beam that data straight back to the United States. The days of scattershot intelligence flights had passed, and missile-launch sites could no longer be hidden just by putting them in the middle of nowhere. Even if the Americans had previously thought those areas too low-priority to examine, the satellites could now examine them with no problem. Of course, this advancement worked both ways — the Americans could see the Soviet launch sites, and the Soviets could see the American ones. But the V-12 quickly became one of satellite technology's confirmed kills, because there was no longer any need to haul ICBMs around by air. And the helicopter didn't serve much practical use anywhere else either. In a war zone, sure, carrying some 200 troops inside sounded pretty cool — but shoot down one V-12, and the enemy takes out half a Soviet battalion in one strike. The same went for cargo. And if cargo had to be airlifted for non-combat purposes, well, why not just use a plane? The situations in which a V-12's vertical-takeoff capability was truly needed — for an amount of cargo that couldn't just be split between multiple smaller helicopters — were extremely limited, and they certainly didn't justify the cost. ## The Greatest Helicopter That Never Was The Soviet Air Force outright refused to accept the helicopter design for trials. The Mil Design Bureau continued to work on the project for a little while, but the entire thing was mothballed by 1974. Of the two prototypes built, one was kept at Mil's helicopter plant, while the other was donated to an Air Force museum near Moscow to be displayed to the public. An anticipated second version of the craft, meant to carry even heavier loads, was also cancelled. Mil briefly entertained the idea of a variant for commercial use in Siberia, but again, there just wasn't a need for a helicopter of the V-12's size. If there's any small victory the V-12 achieved, it might have been getting the Americans to waste some of their own R&D budget trying to build a competitor aircraft — but that's just about all the helicopter ultimately accomplished. Today, the V-12 lives on exclusively through the records it set and the prototypes that continue to capture the public's imagination. It's a testament both to the V-12's incredible feats of engineering and to its obsolescence that many of its records stay unbeaten today, with no known aircraft currently in development that would even come close to its lifting capacity. It will probably hold those records for a very long time. Its successor craft — most prominently the Mil Mi-26 — have given the V-12 no reason to step back out of retirement. In all likelihood, the V-12 will remain the world's greatest helicopter that never was. ## Key Takeaways - The Mil V-12 remains the largest helicopter ever built, at 37 meters long with a 67-meter rotor span and a maximum takeoff weight of over 100,000 kilograms. - It was conceived to airlift ICBMs to remote launch sites without leaving the telltale roads, rail lines, or airstrips that American U-2 spy planes could spot. - Rather than a single or tandem rotor, the V-12 used a transverse layout — two equal-size rotors on support wings, the same basic concept later used by the V-22 Osprey. - Its first test flight ended in a crash from violent shaking and an involuntary roll, but after a year of fixes it broke eight world records and won the Sikorsky Prize. - Spy satellites made the missile-airlift mission obsolete before the second prototype even arrived, and the project was mothballed by 1974 with just two aircraft built. - The V-12 still holds four of its world records, and its successor, the Mil Mi-26, made any revival unnecessary. ## Frequently Asked Questions ### Why did the Soviet Union build the Mil V-12? The V-12 was designed to solve a nuclear logistics problem: moving intercontinental ballistic missiles to remote launch sites without giving away their location. New roads, airstrips, or rail lines would be visible to American U-2 spy planes, but a concealable helipad and a helicopter big enough to carry an ICBM could keep those sites hidden. ### How big was the Mil V-12? The V-12 was 37 meters long with a rotor span of 67 meters — almost 220 feet — from tip to tip, and a maximum takeoff weight of over 100,000 kilograms. Its freight compartment was 28 meters long and about four and a half meters tall and wide, large enough to hold a city bus and rated to carry 196 passengers. ### What made the V-12's design unusual? Instead of a single top rotor or a tandem layout like the American Chinook, the V-12 used a transverse layout, with two equal-size rotors mounted on the ends of support wings for stability. It was powered by four D-25 engines of 6,500 horsepower each, and the same transverse concept later appeared on the Bell-Boeing V-22 Osprey. ### Did the Mil V-12 ever crash? Yes. Its first test flight went badly, with the helicopter shaking so violently that it caused an involuntary roll and ended up smashing into the ground and popping its own tires. After a year of repairs and modifications, the rebuilt V-12 flew successfully and went on to break eight world records. ### Why was the V-12 cancelled? The arrival of spy satellites made the missile-airlift mission obsolete, since launch sites could no longer be hidden simply by being remote. The helicopter also had little other practical use, the Soviet Air Force refused to accept it for trials, and the project was mothballed by 1974 with only two prototypes built. ### Does the Mil V-12 still hold any records? Yes. The V-12 broke eight world records for lifting heavy cargo to altitude, and it still holds four of them today. With no known aircraft in development that would come close to its lifting capacity, it is likely to keep those records for a long time. ## Sources - [Original MegaProjects video: The Mil V-12: The Largest Helicopter Ever Built](https://www.youtube.com/watch?v=676dbUox9ZU) - [Encyclopaedia Britannica — Mil Mi-12](https://www.britannica.com/technology/Mil-Mi-12) - [AeroTime — The largest helicopter ever built: Mil V-12](https://www.aerotime.aero/articles/26072-the-largest-helicopter-ever-built-mil-v-12) - [Aviastar — Mil Mi-12 (V-12)](http://www.aviastar.org/helicopters_eng/mi-12.php) - [Hero image source](https://commons.wikimedia.org/wiki/File:Mil_V-12_Mi-12_(8912725374).jpg) by Clemens Vasters / Wikimedia Commons, CC BY 2.0. ## Related Coverage - [The Lockheed U-2: Spying Before Satellites](/article/lockheed-u-2-spy-plane-spying-before-satellites) - [The Duga Radar The Secret Spying Soviet Radar Next To Chernobyl](/article/the-duga-radar-the-secret-spying-soviet-radar-next-to-chernobyl) - [The Convair B-36 Peacemaker: The Absolute Unit That Carried America Into the Cold War](/article/convair-b-36-peacemaker-cold-war-bomber)