Mine flail

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A mine flail is a vehicle-mounted device that makes a safe path through a mine-field by deliberately detonating mines in front of the vehicle that carries it. They were first used by the British during World War II.

The mine flail consists of a horizontal, rapidly-rotating rotor mounted in front of the vehicle on two arms. Fist-sized steel balls are attached to the rotor by chains (flails). The rotor's rotation causes the flails to spin wildly and to continuously and violently strike the ground. The force of these strikes mimics a person or vehicle passing over the mines and causes them to detonate, but in a safe manner that does little damage to the flails or the vehicle.

Contents 1 World War II Use 2 Modern use 3 Surviving Vehicles 4 See also 5 References 6 External links

[edit] World War II Use

The idea is commonly attributed to a South African soldier - Major A. S. du Toit (then a sergeant in the Artillery). A test rig was constructed in South Africa and results were so encouraging that du Toit was promoted and sent to England to develop the idea.^[1]

Before du Toit left for England, he described his idea to Captain Norman Berry, a mechanical engineer who had been sent to South Africa to evaluate the system. Captain Berry later served in the British Eighth Army during the Western Desert Campaign and on his own initiative, carried out his own experiments with mine flails in the spring of 1942. Later, a Major L. A. Girling, was given the task of developing a similar device after it had been independently re-invented by another South African officer. When Captain Berry heard of this, he handed over his previous work to Girling (Girling had had no idea he was duplicating du Toit's ongoing work in England as that was still highly secret).

Development by Girling's team in Egypt continued over the summer of 1942 and resulted in the Matilda Scorpion (the name came from a senior officer's remark on the tank's appearance). This was a Matilda tank fitted with a rotor, mounted on two arms, roughly 6 feet (1.8 m) in front of the tank. The rotor carried 24 flails and was driven at 100 rpm by a 105 horsepower (78 kW) Ford V8 engine. This second engine was fitted in an armoured box mounted on the right side of the tank, the outside box included space for a crewman who operated the device. Although the mine sweeping process was slow, the Scorpions raised such a huge dust cloud when used in the desert that they obscured themselves from German gunners. The cloud also blinded the drivers and the crews had to resort to wearing their gas masks in order to breathe.

Twenty-five Matilda Scorpions, manned 42 and 44 Royal Tank Regiment of 1st Army Tank Brigade, were available by October 1942 and took part in the Second Battle of El Alamein. German minefields around El Alamein contained around three million mines and had been named the Devil's gardens by the German commander, Erwin Rommel. Breaching these minefields was vital to the Allied battleplan.

During the battle, the Scorpions were less successful than hoped.^[2] While reasonably effective at mine clearing, the hastily developed flail system tended to be unreliable and broke down frequently. Also, there were frequent engine failures as the air filters were overwhelmed by the volume of dust. Much of the mine clearing that was critical to the Commonwealth victory still had to be carried out by hand. One unexpected effect was that the noise, dust and terrifying appearance of an approaching flail tank caused several Axis infantry units to surrender without resistance.

After the battle, a Mark II version of the Scorpion was produced by removing the main gun as that was thought to be redundant. Controls for the flail were moved into into the turret so the flail operator could be moved inside the tank, taking the place of the gunner. The air filters were improved and unreliable components strengthened. ^[3]. Mark III and Mark IV Scorpions where later developed that where based on the M3 tank. This larger tank was a more suitable mount for a flail than the Matilda and many became available for modification as, by this time, they were being replaced on the battlefield by the M4 Sherman. A small number of these Grant Scorpions were produced and were used during the remainder of the North African campaign and later during the Allied invasion of Sicily. A Mark V Scorpion was based on the Sherman.

Meanwhile in Britain, du Toit had developed in parallel the Matilda Baron. The Baron never saw combat, but it provided experience that led to the successful Sherman Crab - an M4A4 model of the M4 Sherman tank fitted with a mine flail. Many other British tanks were experimentally fitted with flails but only the Crab went into production. Du Toit himself became a strong advocate of a concept called the Parambulator Mine Flail - a self contained device with its own engine, that could be pushed ahead of any tank that was available. However, the consensus of opinion favoured special-purpose tanks with a permently mounted flail system and he returned to South Africa in 1943.^[3]

Unlike the Scorpion, the Crab's flail was powered by the main engine. In Britain, the time and resources were available to carry out the major modifications to the Shermans' transmission that were needed to add a power take off. This removed a major problem of the Scorpion - the outside auxiliary engine with its vulnerable operator. The Crab's rotor carried 43 flails and was driven at 142 rpm by a driveshaft running down the right hand side of the tank. An innovation was the addition of cutters to the rotor that cut barbed wire and stopped the flail from becoming tangled. This feature made the Crab very effective at tearing up barbed wire obstacles. The flail arms could be raised and lowered hydraulically and the Mark II version of the Crab included a system that made the flail rotor automatically track the contours in the ground - this ensured mines buried under a dip in the ground would not be missed. A blast shield between the flail and the tank gave added protection from detonating mines. The hull machine gun was removed as the blast shield and flail occupied its field of fire.

Great attention was paid to marking the cleared path through the mine field. Crabs carried a pair of bins filled with powdered chalk that slowly trickled out to mark the edges of the safe route. They were also equipped with a hopper that periodically dropped smoke grenade markers and a system that automatically fired illuminated poles into the ground at intervals. A pair of lit masts were mounted at the back for station-keeping when several Crabs were flailing together. Dust clouds reduced visibility to a minimum and careful control was essential to make sure the tanks' paths didn't drift apart, leaving an uncleared strip of ground between them.

The Crab had disadvantages. Flailing did not remove all mines. The Crab could only move at 1.25 mph (2 km/h) when flailing and the gun had to point to the rear so the tank could not fire. As with the Scorpion, flailing raised a huge cloud of dust. Despite all this, it was an effective and valuable vehicle during and after D-Day, especially as the Germans made extensive use of minefields to slow the Allied advance through France and the Low Countries. By the final months of the war, Germain minefields had ceased to be a major problem and it was proposed that the surviving Crabs should have their flail equipment removed and be converted back to regular Shermans^[3] - an idea that was bitterly resented by Crab crews, who considered themselves to be a highly-trained elite. In the event this never occurred and the Crabs spent the last part of the war clearing old minefields behind Allied lines.

The Sherman Crab saw limited use by the American army, the Crab Mark 1 was designated the Mine Exploder T2 Flail and the Crab Mark II the Mine Exploder T4. The Mine Exploder T3, T3E1 and T3E2 were all experimental American Sherman mine flails that were cancelled. The flail idea was also copied by the Japanese, who produced a vehicle called the Mine Clearing Tank G that was based on a Type 97 Chi-Ha tank. In the 1950s, the British Army used Churchill tanks fitted with flails - this was the Churchill Flail FV3902 or Toad.

[edit] Modern use

Mine flails continue to be used although their role has changed. During World War II, they were used in combat to clear paths through a defender's mine-field during a large-scale assault. The modern equivalents are used both by armies and by non-military organisations engaged in humanitarian demining. Unlike their WWII predecessors, modern mine flails are intended for use in secure areas. They are not armed combat vehicles and only carry the armour necessary to protect the operator from mine explosions. Many modern mine-flail vehicles are intended to destroy only anti-personnel mines and receive significant damage if they encounter a larger anti-tank mine. Mine flail vehicles that can cope with anti-tank mines tend to be larger, heavier, more cumbersome and more expensive to operate.^[4]

Several designs, such as the Danish Hydrema 910, are based on a truck chassis with an armoured cab and a flail mounted behind on what would otherwise be the cargo space. They are able to drive to the mined site like any other road vehicle. During flailing operations, they slowly drive in reverse over the mine field - in this way, the cab is kept as far as possible from any detonations. Some mine-flail vehicles are operated under remote-control for safety. The Dok-ing MV4 is a small, remote-controlled vehicle which is more easily moved to remote or inaccessible locations and may be used in more confined areas.

Tanks are still occasionally used to carry flails. However, they have the disadvantage of having the driver at the front, close to the flail and any explosions. Also, the minimum speed of tanks tends to be too fast for effective mine-clearing and the weight of tanks makes them difficult to transport (by contrast, the 18-ton Hydrema 910 is light enough to be moved by air in a C-130 Hercules.) The tanks used have generally been obsolete models that have been highly modified - some work under remote control, others have had the driver's station moved to the rear. In modern times, there has been little military interest in an updated equivalent of the Sherman Crab or Matilda Scorpion - a substantially unmodified tank still capable of combat. In battle, the modern preference is to detonate mines with explosive devices such as the Antipersonnel Obstacle Breaching System or the Giant Viper. During the Gulf War, the U.S. 2nd Marine Division made an attempt to breach an Iraqi mine field with a mine flail mounted on an Armored bulldozer. But the flail was destroyed and the bulldozer crippled by an Iraqi anti-tank mine.^[5]

Mine flails have the advantage of being able to clear most mines from an area comparatively rapidly - the manufacturer of the Aardvark Mark 4 quotes a maximum rate of 3000 square meters (0.75 acres) per hour, however 600 m² is more usual. Also, flails don't place their operators at significant risk, unlike manual demining. ^[6]

However they have come under criticism. ^[7] They represent a large cost for non government, humanitarian organisations (an Aardvark Mine flail costs around $500,000 US.) They consume a lot of fuel as a powerful engine is needed to drive the rotor if the flails are to strike the ground with enough force to be effective. Mine flails can be unreliable and require spare parts that are difficult to obtain in remote regions. This leads to high operating costs and possibly lengthy periods when the flails are out of service.^[4]

It is known flails don't reliably detonate all the mines in the area being swept, leaving it potentially hazardous. Some mines, such as the Italian MAT/6 mine are designed to be flail resistant; mines that have been buried for many years may fail to detonate when struck but may still be hazardous. Also, some mines are smashed without being detonated. This is referred to as a disruptive strike and still renders the mine harmless but the ground is contaminated with metal debris and undetonated explosive material. This makes it harder to carry out the necessary manual check of the area after the flail had finished, either with metal detectors or explosive sniffer dogs. There are also anecdotes of mine flails flinging live mines out of the mine field and into safe areas. An experiment with inert mine-analogues ^[8] demonstrated this can happen as some were thrown over 10m by the flail, in one case, 65m.

An additional problem is the vulnerability of current mine flail vehicles to anti-tank mines. This means that if the presence of anti-tank mines is suspected, the mine-field must, paradoxically, be manually checked first to make it safe for the mine flail.^[9]. These problems have led many humanitarian demining organisations to abandon the use of flails.^[4]

The clearance rate of mine flails can approach 100%, although rates as low as 50%-60% have been reported. ^[10] Effective clearance requires both suitable conditions and experienced flail operators. Current mine flails do not operate effectively on a gradient greater than 30% or on ground that is especially dry or boggy. A large number of rocks, greater than around 5cm in diameter, will also hamper flailing as they will tend to shield mines from flail blows. This is a particular problem in the Lebanon and the United Nations mine clearing operations in the south of that country have barred the use of flails.^[10]

Assessing flail effectiveness is difficult as it is hard to distinguish between a mine that has been missed by the flail and an aging mine that has been struck but has failed to detonate. To be sure which is the case, it would be necessary to disassemble the mine and examine its fuse - a lengthy and dangerous procedure that is hardly ever carried out in the field. Because of this, all apparently intact mines are reported as being 'missed' by the flail and it has been suggested this leads to an under-reporting of the mine flail's clearance reliability ^[8].

Experience in Afghanistan ^[9] suggests that, despite the disadvantages, mine flailing can, in certain circumstances, be a valuable step in a multi-stage demining process. They remove most mines but the area must still be checked manually. This is made easier by the fact that the flails strip most vegetation from the minefield and are very effective at disposing of trip-wire triggered Booby trap devices.

[edit] Surviving Vehicles

Sherman Crabs are displayed at the CFB Borden Military Museum, Ontario, Canada; the Yad La-Shiryon museum in Israel and the Overloon War Museum in the Netherlands. The Bovington Tank Museum in England has both a Sherman Crab and a Churchill Toad in its collection. A fifth Sherman Crab is exposed as a monument at Westkapelle in the Netherlands, but it is missing its mine flails and it looks like a usual Sherman tank [1].

[edit] See also

• Demining
• Mine roller
• Mine plow
• Hobart's Funnies
• 79th Armoured Division

[edit] References

[edit] External links

• Churchill Toad Restoration The world's only operating Churchill Toad is now restored and running.
• Recollections of a Sherman Crab crewman, BBC People's War Archive.
• Article from the Bovington Tank Museum on World War 2 mine flails.
• Description of the Danish Hydrema 910 Mine Clearing Vehicle.
• Danish Army website describing the Hydrema 910.
• Website of Aardvark Clear Mine Ltd. - Manufacturer of the Aardvark mine clearing vehicle.
• English Language Manufacturer's Website of the Croatian Dok-ing mini-mine flail vehicle.
• Article about the use of the Aardvark and Hydrema by the US military in Afghanistan