Mine flail

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 in 1941 to evaluate the system.

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).

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.

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.

[citation needed] After the battle, a Mark II version of the Scorpion was produced by removing the main gun, as that was thought to be unnecessary.

[4] The Baron's problem was that, like the Scorpion, the rotor was powered by external, auxiliary engines that made it too wide to cross a Bailey bridge and which had to be removed if it was to be transported by rail.

Du Toit himself had become a strong advocate of a concept called the perambulator mine flail - a self-contained device with its own engine, that could be pushed ahead of any tank that was available.

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.

Dust clouds reduced visibility to a minimum, and careful control was essential to make sure the tanks' paths did not drift apart, leaving an uncleared strip of ground between them.

The other two would hang back on the flanks and give fire support, but were ready to move forward to replace one of the flailing tanks if it was disabled.

A Teller mine buried up to 5 inches (13 cm) deep would be set off, but the resulting explosion would destroy a single flail chain, which would have to be replaced at some point.

[9] The Crab could only move at 1.25 miles per hour (2 km/h) when flailing, and the gun had to point to the rear, so the tank could not fire even if the gunner could see his target.

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.

[10] 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.

The Swiss Digger DTR D-250 is a smaller, four ton, remote-controlled vehicle that is more easily moved to remote or inaccessible locations and may be used in more confined areas.

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 (mine-clearing line charges), such as the Antipersonnel Obstacle Breaching System or the Giant Viper.

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.

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.

[16] Experience in Afghanistan [17] suggests that, despite the disadvantages, mine flailing can, in certain circumstances, be a valuable step in a multi-stage demining process.

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.

The Sherman preserved on the seawall at Westkapelle in the Netherlands to commemorate the amphibious assault on Walcheren in November 1944 was originally a Crab, but the flails have been removed.

Another Toad was restored to full working condition in England and in May 2008 was acquired by Jacques Littlefield's Military Vehicle Technology Foundation in California.