"What the hell is that?
Oh, it's a Hind".
-my response to a photograph of an Mi-24A.
The Hind is a combat helicopter and troop carrier produced by Mil for the Soviet Union in the 1970s. For a long time it held the helicopter world speed record. Until a Westland Lynx broke it in 1986 nothing could touch the Mi-24 for straight line performance, and still nothing but a Lynx can. Of course there's more to air combat than that, but moving swiftly on...
The Hind was Russia's tank killer, roughly equivalent to the US's AH-64 Apache. It was intended to replace the Mi-8 Hip troop carrier which, without much success, had been pressed into service as an attack helicopter. The Mi-24 has since been superseded by the Ka-50 Hokum but unsurprisingly remains in service with the Russian Army.
A prototype was produced in 1969, the design becoming operational in 1970. The first Hinds, the Mi-24As, look quite different to the 'D' variant most commonly seen these days. Imagine an old railway boxcar chopped in half with a greenhouse on the front, a wind turbine on the back and a tricycle underneath. That's basically the shape of the Hind-A.
The fuselage is 17.5 metres long and about 2 metres wide. It is very bulky as it has a cabin to the rear of the cockpit that can accommodate eight armed troops. Both have an air overpressure system to provide some protection in NBC environments. To the rear of the cabin doors on either side of the fuselage are short wings about 3 metres long. These provide up to 28% of the Mi-24's lift when it is in forward flight and each have three hardpoints, for armaments such as rockets or air-to-air missiles.
The main rotor has five blades and a span of 17.3 metres (almost three metres wider than the rotor span of an Apache). The tail rotor is 3.9 metres in diameter and has three blades, mounted on a swept-back tail fin. Uneven numbers of rotor blades are quite a trend in Russian helo design, one of my sources noting that more numerous and longer rotor blades make a helicopter more suited to operation from high-altitude airfields where the air is thinner. They also make a helicopter quieter because they do not have to turn as fast.
The cockpit is the odd thing about the Mi-24A. It just looks.. weird. I mean apart from the fat, ugly fuselage and its squatting stance on its tricycle undercarriage. The cockpit is actually not unlike that of the Apache - a tandem design, with the gunner at the front, the pilot behind and the navigator behind him - only without the kinks along the top of the window frame. However the Hind-A's nose ends where the cockpit window ends, so really its cockpit is its nose. Immediately behind the cockpit (above the passenger cabin) are two round air intakes for the twin Isotov TV3-117 engines, which output 2,200 horsepower each.
All of the areas surrounding the engines, cockpit and passenger areas are protected by armour and the rotor head is titanium, able to withstand 20mm cannon rounds. Unfortunately the gaping engine exhaust outlets, beneath and on either side of the rotor mast, were completely open, rendering the Mi-24 highly vulnerable to heat-seeking missiles. But we'll come back to this.
In 1975 a stripped-down Hind-A was used to set a helicopter world speed record of 230mph (368kmh), as well as rate of climb and altitude records. The Hind is still the second fastest helicopter in the world.
This variant of the Hind is the most ubiquitous, owing to the fact that almost all older variants were eventually converted to this one. It was introduced in 1975 or 1976 and was a significant redesign; the section forward of the engines was completely replaced, with redesigned air intakes for the engines and twin 'bubble' cockpits mounted in tandem, the pilot's cockpit above and behind the gunner's. The navigator position was removed altogether. The other major modification was slung underneath the gunner cockpit - a moveable four-barrel, 12.7mm rotary machine gun with a 4000 round-per-minute fire rate and a 1.5km range.
The Hind-E was more an evolution of the Hind-D than a major redesign. It is easily confused with the Hind-D, but there are in fact more 'E's operating than 'D's. It was rolled out in 1976, the main differences between it and the 'D' being a new missile control pod (previously, the gunner had to manually fly ground attack missiles to their target; now he just had to keep a crosshair centred on it), a new heads up display for the gunner and also a backup set of flight controls for the gunner. The only way of telling a Hind-E from a Hind-D is the missile control pod, which is behind and to the left of the chin-mounted gun pod.
The Hind-F improved things further, with modified avionics and a 30mm cannon in place of the 23mm machine gun. Unfortunately the recoil from the weapon was so strong (the airframe had to be modified to withstand it) it was impossible to mount it in a moveable turret like the machine gun, meaning that pilots now had to point the whole helicopter at a target they wanted to hit. The cannon was fitted after combat experience showed there were many targets too tough for the Hind-Ds machine gun but not worth wasting rockets on. A later compromise replaced this static cannon with a moveable 23mm one.
- Hind G-1 - a battlefield nuclear reconnaissance machine, with air sampling sensors in place of the gun turret and small arms fitted to the wings for scooping up soil samples. Hind-G1s were often seen loitering around the Chernobyl nuclear power plant after it blew up. About 150 of these were built.
- Hind G-2 - A pure reconnaissance variant, with a large camera fitted in the passenger compartment and a moveable camera in place of the targeting gear of the Hind-E. It keeps the machine gun of its predecessors but does not carry missiles. 163 of these were built.
- Mi-25/Mi-35/Mi-35P - these are export versions of the Hind-D, Hind-E and Hind-F respectively. They are the same as their production templates but carry slightly downgraded avionics.
- Mi-24M/Mi-35M - a 1999 variant by the now-commercial MiL organisation (Rostvertol). All the features on this helicopter are available as upgrades for older variants. These include fibreglass main rotor blades, a four-bladed tail rotor (much like that of the Apache), improved avionics and night vision capabilities, fixed landing gear and a sensor suite comparable to that of the Apache. Further, the stub wings have been cut down to improve the helicopter's hovering abilities. Supplied versions are also likely to be fitted with new Klimov VK-2500 turboshaft engines with 200bhp more than the old Isotov engines.
The Hind in Afghanistan
The Mi-24 is most commonly associated with Russia's invasion of Afghanistan in 1978. Hinds were commonly used to support troops and armour, as well as occasionally ferrying troops into otherwise-hard-to-reach areas of enemy territory.
It was here that another serious design faux pas of the Hind came to light. As mentioned earlier, the engine tailpipes were completely unprotected leading to a great many losses from US-supplied Stinger missiles, which could easily home in on the Hind's heat signature. Further, rebel soldiers quickly learned how easy it is to down a helicopter with a well-placed rock. Those tail rotors are delicate things.
Many bad experiences in Afghanistan (333 helicopters were lost in the ten years of Soviet occupation) prompted an upgrade pack for the Hind-D with various countermeasure modifications, including a radar-warning receiver (RWR), a chaff/flare dispenser and an infrared jammer (all this was fitted as standard to the Hind-E). Also, those hot exhausts were covered up with boxy filtration systems and the intakes with dust filters, making a Hind more difficult to hit with a heat-seeking missile like the Stinger. Unfortunately this also had negative effects on both speed and manoeuvrability.
The Hind is reportedly difficult and unforgiving to fly. Its poor manoeuvrability does not combine well with its high top speed, particularly in low-level flying scenarios. Then there's the whole main rotor/tail boom thing, meaning even attempting strong manoeuvres is a bad idea. Flying with troops makes matters worse. Aside from the significant weight increase, flight crews reportedly found carrying passengers a significant distraction, particularly when under fire. Some Hinds had the armour removed from the passenger section completely to reduce weight. However the one boon of carrying soldiers was the ability of a Hind to watch its own back; the small windows in both crew doors can all be opened and are just the right size for an assault rifle. Although the Hinds rarely carried troops, an armed technician was often carried in the back to provide some defence against enemy soldiers.
This still left the Hind's rear vulnerable, so experiments were made with fitting a machine gun underneath the tail boom, which would be reached through a crawl space at the back of the crew compartment. This was found impossible to work with, hot and full of exhaust gas as it was, and an overweight Soviet general getting stuck in it during a demonstration probably sealed the fate of that bright idea. In its place a rear-view mirror allowed the pilot to at least see what was behind.
Despite the overall failure of the Soviet campaign in Afghanistan and the Hind's high rate of attrition, the design seems to have fared reasonably: Mujahadin rebels were apparently terrified of the helicopter, calling it "Shaitan-Arba", or "Satan's Chariot". One source notes that pilots were often able to scare Mujahadin soldiers off by simply manoeuvring aggressively at them (useful if they were out of ammunition. Pilots became highly proficient, performing manoeuvres and attacks that even the designers considered impossible. The poor suitability of the Mi-24 for night operations was not a deterrent to the pilots, who were trained to fly at night unassisted, using flares to illuminate suspicious targets.
Some of the Hinds were passed on to pro-Soviet Afghani forces prior to the Soviet withdrawal from the area and these continued in service for some time during the civil war that followed. Some defectors flew their Hinds to nearby Pakistan. Some of these were reportedly bought by the US Army to use as aggressors in training exercises, though the means by which this occurred are still an official secret. At least one came from France—which captured three during the rebel uprising they supported against the Chad government—as well as the US and Libya. One of the three Hinds was handed over to Britain, though there is no information on what, if anything, it was used for.
Apparently recognising the limitations of the Mi-24 design, Russia arranged a competition to replace it, which was jointly "won" by MiL's Mi-28 Havoc and Kamov's Ka-50 Hokum. Due to the collapse of the Soviet Union and dwindling funds neither aircraft has been produced full scale so it seems likely the Mi-24 will be servicing many for some time to come. It is one of Russia's biggest export successes, having been supplied to up to 30 countries in numbers from 15 to 60. Many are still on active duty, India being one of the most enthusiastic operators.
Although the Hind is very fast its manoeuvrability is poor, probably due to its bulk and weight. The west did not see one until 1972 on the East-West German border. Both sides tested each other, much as their submarines used to play cat and mouse in the world's oceans, seeing who could creep up on whom and remain unseen the longest.
During the 1980s an encounter between the two sides' helicopters graphically showed a serious flaw in the design of the Hind. An American AH-1 Huey Cobra met one while flying along the border between East and West Germany; the Hind had been ordered to intercept the Cobra and the pilots chased one another along the border for a while, the American pilot constantly pulling up sharply to force his faster opponent to overshoot. Apparently trying to duplicate this manoeuvre, the Russian pilot eventually pulled up too hard and stalled his aircraft. When attempting to pull out of the dive that followed, the main rotor blades of the Hind hit its tail boom and the helicopter crashed, killing everyone aboard.
This particular 'quirk' - the helicopter's main rotor striking the tail boom under particular flight conditions, with disastrous consequences - has long plagued the Mi-24. Another is its retractable undercarriage, though this is more the fault of convention than anything. Most helicopters have fixed undercarriage and reportedly some of the early pilots of the Mi-24 forgot to lower the undercarriage when landing.
A further deficiency in the Hind's design is that it is capable of carrying more weapons than it is capable of hovering with. Let me just say that again: the Hind cannot maintain a hover. Much like the British Harrier aircraft, it is incapable of a vertical takeoff with a full weapons load and must therefore perform a rolling takeoff. Further, the large stub wings which carry the majority of the weapons prevent Hinds from hovering, because they block a large portion of rotor downwash (ironically a fully-loaded Hind wouldn't be able to get off the ground without those wings). The later Mi-35 fixed this somewhat by reducing the length of the wings.
It is difficult to imagine - especially given how flush the Soviet military and design bureaus must have been at the time this was conceived - the circumstances under which a flying kitchen sink like the Hind would be desirable. Military hardware is and has generally been quite specialised; there are few examples of vehicles that have combined major roles like the Hind does troop transport and ground attack.
Furthermore, the Hind's dual role has apparently rarely been exploited; it has mostly been used as an attack and surveillance platform, only occasionally as a troop carrier. Reportedly the Hind was/is often used as an armed escort for Mi-8s doing the troop carrying or as a team with Su-25 Frogfoot ground attack aircraft. In attack roles the Mi-24 is outclassed by successor the Ka-50 Hokum and the U.S' AH-64 Apache in virtually every respect. However it does have the trait common to much former Soviet hardware, that being the relatively low-tech design makes field maintenance much easier than equivalent American hardware. Although the low level of sophistication of captured Russian equipment has been generally derided there's something to be said for hardware that can withstand the EMP from a nuclear blast.
The Hind is an aircraft I imagine former pilots of being very misty eyed about; the pilot who was charged with learning how to fly the first Mi-24 the US acquired described it as being "more fun to fly than any other helicopter he's ever got his hands on"(1). Other Army pilots praised its unique performance, saying it is "very quiet and gives a very smooth ride, "like an old '62 Cadillac."(1) Not bad for a helicopter notorious for chopping its own tail boom off. And not being able to hover.
This writeup's sources are quite a mish-mash of information, using sources that never quite agree. Thus, I describe them as further reading. I particularly recommend the first source for information on far more Hind variants than the majority of noders would care to read about.
- Goebel, Greg; "The Mil Mi-24 Hind & Mi-28 Havoc";
- helis.com (Author not specified); "Mil Mi-24 Hind";
- US Centennial of Flight Commission; "Mi-24 Hind "Krokodil"";
- Pike, John; "Mi-24 HIND";
- BBC (Author not specified); "Hot air and politics don't always mix";
- Balloon Life (Author not specified); "FAI Challanges Official Report on Belarus Balloon Shoot-Down";