Flails and the Pookie

Commenters and my blogging contemporary at Defence of the Realm, Dr Richard North, mentioned some interesting information that I thought worth exploring as a follow up to the Talisman post.

A bit more background on these subjects then…

Flails

Most people have heard of flails, having seen them in relation to D Day or North Africa and wonder if they would be part of a solution for the Counter IED mission in Afghanistan.

The flail tank was invented by a South African Army Major in 1942, Captain Abraham du Toit, although there were patents before that and another South African officer also came up with a similar idea independently. After the customary official disinterest, duplication of effort and ingenious persistence the idea eventually came to fruition as a collaborative effort in the North African desert and resulted in the Matilda Scorpion.

Matilda Scorpion Flail Tank North African Desert WWII
Matilda Scorpion Flail Tank North African Desert WWII

The Scorpion flails were driven by a separate engine enclosed in the box on the right, this also included space for the operator, must have been rather warm.

Writing in a post battle report Lt William Schneck wrote

The mine flail tank idea began in 1941, with Abraham S. J. du Toit, a motor engineer in civilian life and a sergeant in the South African artillery, who developed a novel device that detonated mines by beating the ground with heavy chains or wire ropes driven by a rotating drum. A test rig was built on a truck and demonstrated in Pretoria, South Africa, where a short film was produced. After General Auchinleck saw the film, he thought it was a brilliant idea and sent Sergeant du Toit to England to pursue his invention in secrecy. The general felt that secrecy was vital in order to maintain the device’s tactical surprise and value, but keeping it secret in the Middle East or South Africa was impossible. It was intended to mount it on a tank chassis for combat use. Sergeant du Toit was soon promoted to major and was closely involved in the development in Britain of what became the Matilda Baron. Although the Baron never saw combat, it did provide the knowledge and experience that eventually led to the development and fielding of the highly successful Sherman “Crab” flail tank which General Hobart used during the Normandy landings in 1944.

Before Sergeant du Toit had left for England, he had sketched out his idea for Captain Norman Berry, the South African Chief Mechanical Engineer for the 8th Army. Captain Berry soon became tired of waiting for results from England and, on his own initiative, went ahead with some free-lance experiments while the 8th Army was still entrenched along the Gazala Line in the spring of 1942. There was no precedent for frontline troops to design and build a piece of equipment of such importance and complexity. Later, during the summer, Lieutenant-Colonel Mill Colman, a member of the South African Engineer Corps, developed what he thought was a novel idea for mine clearing. The idea had come to him when he noted a tracked vehicle driving by with a length of wire entangled in its track sprockets. With each revolution of the sprocket, the wire hit the ground with great force. Based on this, he thought that it might be possible to build a thrashing device that could detonate mines. Major L. A. Girling, Commander of the 21st South African Corps Field Park Company, was tasked with constructing the first experimental unit. They called it a “mine destroying device.” Captain Berry, hearing of the latest rebirth of the flail idea, told Major Girling of similar previous developments and described how Major du Toit had been sent to England by General Auchinleck to work on a similar idea in conditions of tight secrecy. So secret, in fact, that the Allied command in the Middle East had forgotten about the matter. Captain Berry gladly unearthed the remains of his earlier experiment and handed the contraption over to Major Girling’s team of engineers, consisting of himself, Captain G.J. Barry, Lieutenant Hofmann and

Lieutenant C.D.B. Cramb. Work on the prototype flail tank commenced within twenty-four hours and by 6 August, the first mock-up was completed. This first flail prototype was christened the Durban Mark I, after Lieutenant-Colonel Colman’s hometown in South Africa. The Durban Mark I incorporated many of Captain Berry’s ideas, including an auxiliary 105-horsepower Ford V8 engine mounted in a sponson (an armored box) on the right hand side of the Matilda Tank’s hull powered roller supports to a level box and then to the drum suspended above the ground. The horizontal flail rotor was held by two lattice girder arms about six feet in front of the tank and three feet above the ground. The rotor covered the entire width of the tank and was rotated in the same direction as the tank’s movement, at a speed of approximately 100 revolutions per minute. The rotor was equipped with 24 flails, or chain assemblies, that hit the ground with a contact length of approximately 20-cm. On later versions, fielded after the Second Battle of El Alamein, the boom that carried the rotor was modified so that it could be elevated and depressed by means of hydraulic cylinders to aid in mobility when not in use.

After the tests, Major Girling’s team continued to refine their design. On 12 September, the Durban Mark I was demonstrated for the 8th Army’s corps commanders and their chief engineers. Generals Alexander, Commander-and-Chief, Middle East, Montgomery, Commander 8th Army, and Morshead, Commander 9th Australian Division, witnessed Scorpion demonstrations and were impressed with its capabilities, considering the short amount of time invested in the project. Major Girling was congratulated for bringing the project to such a successful conclusion so quickly. Brigadier Ray remarked that, in appearance, the prototype resembled a scorpion and the name stuck. General Montgomery, a deeply religious and austere man, felt the name appropriate and quoted from the First Book of Kings (Chapter 12, Verse 14): “My Father has chastised you with whips, but I shall chastise you with scorpions.” Having observed the new, unprecedented invention, General Montgomery said that he wanted twelve for the coming attack. Brigadier Kisch had explained that the production of so large a number would have to be approved by General Headquarters and that it would mean suspending other production work. To this, General Montgomery replied, “Don’t belly-ache, order two dozen.” The next day Brigadier Kisch ordered the fabrication of an additional twenty-four of the new “Scorpion” mine destroyers, combined with the first prototype, this would provide the 8th Army a total of twenty-five Scorpions for Operation Lightfoot.

According to Major Reid of the New Zealand engineers, “This idea had great possibilities, especially from the sappers’ point of view, as if we could get tanks to clear gaps through minefields we could anticipate a much longer life.” Compared to the other available alternatives such as rollers and hand clearance, the flail-type mine clearance system appeared to be far superior.

Used operationally in the 1942 second Battle of El Alamein the crew had to wear respirators due to the massive volume of dust the flails threw into the air. Nonetheless, the concept, if not the implementation, was proven. Improvements were made, concepts refined and different tank chassis tried until all the designs and operational experience culminated in the Sherman Crab.

I had a look at General Percy Hobart, a true armoured warfare visionary, and the use of armoured combat engineering in an earlier post. I think it’s one of the most interesting aspects of D-Day. The Sherman Crab was a marked improvement, the flails were driven from the main engine via a power take off, hydraulic raising/lowering and barbed wire cutters which enabled it to double up as a barbed wire breaching device. One of the most important innovations was a system that allowed the marking of a safe lane, using smoke grenade launchers, an illuminated pole launcher and chalk dispenser. The Sherman Flail performed a vital service during D Day and beyond and its importance should not be underestimated.

Sherman AVRE Flail
Sherman AVRE Flail

Flails were not the only anti mine technology, ploughs and rollers were used before the flail as early as 1918 but the flail seems to have had greater success in the war years because they were lighter and more suited to the type of terrain encountered.

Despite some smaller developments, post war, the fail and roller fell out of favour and the explosive breaching charge like the Giant Viper and Python were generally seen as the answer to minefield breaching.

The flail enjoyed resurgence in the 90’s as the need for humanitarian demining of post conflict areas such as Angola and Afghanistan became obvious. Although the military still have flails in their kit bags, Singapore have recently developed the Bionix Trailblazer for example, the majority of users are now civilian demining organisations.

The Geneva International Centre for Humanitarian Demining has some excellent publications on the subject.

Another well known example is the Hydrema MCV910 (also in service with the Singapore armed forces) and there are many others.

Hydrema 910 MCV Flail
Hydrema 910 MCV Flail

The Aardvark Joint Service Flail Unit is made in the UK by Aardvark Clear Mine, now a wholly owned subsidiary of Penman Engineering and is extremely effective, in service all around the world including Afghanistan

Why not in British service in Afghanistan one might ask.

To understand the reason why flails are unsuitable for use in counter IED operations it is important to understand the difference between a mine and an IED.

Mines are usually well packaged, discrete devices with an integral trigger device. IED’s found in Afghanistan and other places often have the mean of initiation (or trigger) some distance from the charge and this is a problem that all mechanical demining tools have when countering IED’s. Whilst the flail might do its job and initiate the trigger or pressure plate, the main charge could well be a few metres back up the road and directly under the flail vehicle chassis.

Other significant problems include the likelihood of distributing explosive materials indiscriminately and there is the obvious destruction of the ground surface. This might cause problems with a local civilian population, especially if it is repeated.

So although flails have a place in demining operations in a civilian context and minefield breaching (not clearance) in a military operation, their use is quite limited.

The Pookie

With the previous post on Talisman I covered the Husky/Chubby vehicle and detection equipment. The forerunner of the Husky/Chubby was a vehicle called the Pookie, I also had a brief look at this in an older post on blast protected vehicle design.

Pookie
Pookie

The Pookie was a specialist mine detection vehicle, first built in Rhodesia in 1976, comprising a monocoque armoured capsule sitting on an open frame chassis. The donor chassis was Volkswagon Kombi which used low downward force torsion arm suspension and this was combined with surplus Formula One tyres to create a ground pressure of less than 3lbs per square foot, less than a human. This ultra low ground pressure meant that it did not even detonate anti personnel mines and allowed the detector to be used without fear of detonation, the Pookie could drive right over a mine and not set it off.

Detection allowed the mine to be cleared or selectively detonated, standard operating procedure was to detect,mark and retire, with sappers carrying out the controlled detonation or neutralisation.

Each Pookie cost a grand total of R$11,000 each and in short order had handsomely paid for themselves.

In four years of operation not a a single mine was detonated by a Pookie but they found over 550 and had both a practical and psychological effect.

The story doesn’t end there though.

After 20 years of gathering dust the Pookie was revived to play a part in civilian demining operations.

In 1999 Minetech resurrected the vehicle and combined it with a modern Ground Penetrating Radar system from Tricon, a German company specialising in detection equipment. The basic design was improved with a new powerpack, hydraulic steering and power system.

After a series of post trials improvements the Minetech Pookie fleet was deployed to Afghanistan and may even still be there.

Again, more applicable to demining operations rather than combat Counter IED operations but an interesting system nevertheless.

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Sven Ortmann
Sven Ortmann
July 8, 2010 12:00 pm

“In four years of operation not a a single mine was detonated by a Pookie but they found over 550 and had both a practical and psychological effect.”

This does of course imply that soft vehicles could have been protected against those pressure-fused AT mines by a reduction of their peak ground pressure.