Which is why three men could move a 650lb anti-tank cannon across a muddy field in the time it would take a conventional gun crew to unhitch from a vehicle. The problem is that magnesium burns not like wood burns or petrol burns. Magnesium burns at over 3,000° C. It burns underwater. You cannot put it out with water as adding water releases hydrogen gas and causes an explosion.
The crews of the wombat were operating a tank killing weapon built from a material that under the wrong conditions would become a white hot thermite grenade. and the wrong [music] conditions included sustained small arms fire and incendury round or the stress corrosion cracking that the Ministry of Defense was quietly documenting in safety bulletins throughout the 1970s.
So the [music] question this video is going to answer is the one the anti-tank platoon were living with every day. Was the wombat a masterpiece of Cold War engineering, light enough to be mobile, powerful enough to kill a [music] T62? or was it a calculated gamble with the lives of the men operating it dressed up as a weight-saving innovation? The answer, as always, is both, and the details are more extraordinary than either side of that argument suggests.
Welcome to Timeless Arms, the unvarnished truth of the battlefield and the steel that defined it. Hit subscribe now. We are pushing to hit our goals this month, and every person who joins keeps this independent research alive. Now, the problem the wombat was built to solve, and why conventional engineering could not solve it.
Discover more
Skip Content Feature
Uncategorized Content Access
Website Menu Builder
By the mid 1950s, the British army had a problem with no comfortable solution. The threat on the North German plane was Soviet armor, specifically the T-54 and the T62, tanks that combined thick sloped steel with mobility and numbers that NATO’s conventional anti-tank capability struggled to match. The British had the 17 [music] pounder anti-tank gun, a weapon that had killed Tiger tanks in Normandy and proved itself as one of the finest pieces of artillery of the Second World War. It weighed nearly three tons.
It required a tractor to move. Once positioned, a small crew could not reposition it quickly. Against the massed armor doctrine the Soviets were developing. A gun that could not move was a [music] gun that would be flanked. The infantry needed something they could carry, something a platoon could deploy, fire, and move before the return fire arrived.
Something that could reach out to 500 yd and guarantee a kill on a main battle tank. Those three requirements, portable, lethal, and fast, are fundamentally in conflict with each other in conventional gun design. >> [music] >> The recoilless principle was the only engineering path that could satisfy all three simultaneously.
Discover more
Home Page Design
News Website Hosting
Star Gossip Feed
To understand the wombat, you have to understand how it cheated Newton’s third law. In a conventional gun, the explosive force of the propellant pushes the shell forward and pushes the gun backward with equal and opposite force. That backward force is what requires heavy steel carriages, hydraulic recoil spades, and the massive weight of a conventional anti-tank gun.
The recoilless rifle eliminates that backward force by venting it deliberately. At the rear of the wombat’s breach is a large flared venturi nozzle. When the 120 mm propellant charge ignites, a precisely calculated percentage of the high-pressure gas is directed backward through that nozzle.
The forward acting force of the exiting gas exactly cancels the backward acting recoil of the shell [music] moving down the barrel. The gun floats in its cradle. No kick, no hydraulics, no [music] heavy carriage, a 120 mm cannon that two men can lift. The perforated casing makes this possible. Unlike a conventional solid cartridge case that seals all the gas behind the projectile, the wombat’s casing is drilled with thousands of small holes.
As the propellant burns, high-press [music] gas bleeds sideways through those holes into the chamber before being channeled rearward through the Venturi. The pressure inside the casing is controlled rather than contained. The propellant charge had to be precisely tuned to the perforation pattern. Burned too fast and the gun jumped forward too slow and it kicked rearward like a conventional weapon.
Every round was a ballistic balancing act. The barrel itself was smooth boore. Rifling [music] would create rotational torque that interfered with the recoilless balance and added friction that the system could not account for. The [music] price of smooth boore was that the shell needed another way to stay stable in flight. That solution was the spotting rifle.
[music] Mounted on top of the wombat’s massive barrel was an M8C50 caliber spotting rifle. This was the mechanical computer that made the system work. The M8C fired a specialized tracer round that was ballistically matched to the 120 mm HESH shell matched in muzzle velocity matched in trajectory arc matched so precisely that if the tracer sparked on the surface of a target, the gunner knew his main round would hit the exact same point.He would fire the 50 caliber first, watch the tracer travel down range, observe where it struck, and if the aim was correct, immediately pull the main trigger. In an era before laser rangefinders and fire control computers, this was a low technology solution of genuine elegance. It worked in rain. It worked in mud.
It worked in the noise and chaos of a forward engagement where a sophisticated electronic system might have failed completely. The spotting rifle was the wombat’s aiming system, its rangefinder, and its confidence, all in a 50 caliber tube bolted to the top of the barrel. Its weakness was supply. The tracer rounds were expensive and [music] difficult to manufacture.
If the crew exhausted their spotting ammunition, the 120 mm wombat was effectively blind at any range beyond 300 yd. In the logistics chain of a cold war engagement, this dependency was a vulnerability that the weapons designers accepted, but never fully solved. The 120 mm Hessh round is the soul of the wombat’s [music] lethality, and it is one of the most distinctively British pieces of weapons engineering ever produced.
Hesh stands for high explosive squash head. It does not work the way most people expect an anti-tank round to work. A sabot round tries to punch through armor using speed and density. A heat round uses a shaped explosive charge to create a jet of molten metal that cuts through steel. The hesh round does neither.
When the shell strikes the front face of a tank, the thin nose collapses and approximately 30 lbs of plastic explosive squashes flat against the armor plate like a pancake. A base fuse then detonates the charge. This does not pierce the armor. It does not need to. The detonation sends a massive shock wave through the steel plate.
When that wave reaches the inside face of the tank, it causes sporing. A slab of steel, sometimes [music] weighing 20 lbs, is ripped from the interior surface and ricochets around the crew compartment at supersonic velocity. The tank’s own armor becomes the weapon. The crew is killed not by the shell, but by their own protection.
The hesh round was specifically effective against the sloped armor that Soviet tank designers relied upon for protection. Conventional penetrators are defeated by slope. The more angled the plate, the more likely a round is to deflect or lose energy. Hesh does not care about slope. The more angled [music] the surface, the larger the footprint of the explosive squash, and the more severe the spoing on the interior.
The T-54 and T-62’s characteristic sloped glasses plates designed to defeat conventional penetrators [music] were neutral or disadvantageous against the wombat’s main round. And then there was the barrel [music] and the risk that nobody in the official literature wanted to discuss in plain language. The electron alloy, magnesium and zirconium was chosen because it was roughly a third of the weight of steel and could be cast and machined to the tolerances required for a 120 mm weapon.
The weight saving it provided was the entire justification for the wombat’s existence as a portable weapon. Without the magnesium, the gun was too heavy to move. With it, three men could manhandle it across terrain that would stop a conventional gun [music] dead. The danger was intrinsic to the material. Magnesium is highly reactive.
Under sustained small arms fire, an incendiary round, or even high velocity fragments from a nearby detonation, the friction and heat could ignite the barrel. A magnesium fire burns at over 3,000° C. Water makes it worse. The reaction releases hydrogen gas, which then ignites sand, dirt, and carbon dioxide extinguishers are also ineffective.
The only way to stop a burning wombat [music] barrel is to let it burn itself out, which it will do completely, leaving nothing of structural value. Through the 1970s, the Ministry of Defense was quietly issuing safety bulletins about stress corrosion cracking in the electron barrels. If the gun was stored in damp conditions or exposed to salt air without rigorous maintenance, microscopic cracks formed in the alloy under the pressure of a 120 mm firing, those cracks could fail catastrophically. The metal fracturing
under that load generates friction and heat sufficient to ignite the magnesium. There are documented training incidents in which the wombat effectively became a thermite grenade on the range. The crews knew this not from the official briefings which were [music] careful with their language, but from the culture of the anti-tank platoon.
You maintained the wombat obsessively because the alternative was not a malfunctioning weapon. It was a burning one. The Imperial War Museum oral history collection holds accounts from veterans of the British anti-tank platoon of the 1970s and early 1980s. The men who operated the wombat through the peak of its Cold War deployment and into the Fulklands period.
History
Those accounts taken together describe a specific culture that does not appear in the official training manuals. The maintenance routine described in those oral histories was not the schedule from the pamphlet. It was something the platoon had developed through experience and passed laterally between crews rather than down from training establishments.
The specific attention paid to the electron barrel surface at every inspection. The way a number one would run a hand along the alloy after a firing sequence, not to check for [music] heat, which was obvious, but to check for the change in surface texture that indicated the [music] early stages of stress cracking.
A barrel that felt right was trusted. One that did not was reported immediately because the alternative to reporting it was operating a weapon whose failure mode was a thermite fire at close range. The back blast discipline described in those accounts was absolute on [music] exercise and by all accounts remained absolute in the Fulkland’s engagements where the wombat was deployed.
A 120 mm recoilless firing produces a cone of supersonic gas and debris 60 [music] yd deep and 40 yard wide. The wombat announced its position to every enemy within 5 mi the moment it fired. The Porty displacement drill, unporting the 650lb gun under fire and moving to a new position before return fire arrived is described in those accounts as the most physically demanding thing [music] the platoon trained for.
It was also in the Falklands terrain, the thing that kept the crews alive. What comes [music] through consistently in those oral histories is not fondness for the weapon. It is the specific respect a professional gives to a tool that will perform exactly as designed if you treat it correctly and will kill you if you do not.
The magnesium risk was not considered acceptable. It was considered managed managed through training, through maintenance, and through the understanding that the weight saving the electron alloy provided was the only reason the wombat existed in the role it occupied. Remove the magnesium and you remove the portability. remove the portability and the wombat is just another heavy anti-tank [music] gun that cannot keep up with the infantry it is supposed to protect.
The Port Land Rover was the wombat’s tactical master stroke and it was simultaneously a perfect illustration of what British infantry engineering looks like when it is working at its most creative. The series 2 and three Land Rovers used for porte mounting were stripped of doors, roof, and windscreen. Internal ramps allowed the wombat to be rolled into the vehicle bed and secured.
The crew could drive to a fire position, engage, and be moving again before return fire arrived, provided everything worked as planned. If the gun was fired from the vehicle, the back blast would strip the paint off the Land Rover and shatter every piece of glass within 30 yards. The solution was a long firing lanyard that allowed the crew to stand clear of the vehicle while the weapon [music] fired from its mount.
This was not elegant, it was effective. The preferred tactic was to unport entirely. The Land Rover would reverse into a concealed position, and [music] the crew would slide the 650lb gun down the ramps and manhandle it into a firing point. Three men, 650 lb, across whatever terrain the North German plane or the Falkland Islands happened to be presenting that day.
The magnesium alloy made this possible. Nothing else would have. The question that the late 1970s safety bulletins make unavoidable is this. What if the Soviet composite armor had arrived 5 years earlier? The T64 and T72 introduced ceramic and plastic composite armor, specifically designed to defeat HESH rounds by absorbing the shock wave before it could cause spoing on the interior face.
By the late 1970s, the wombat’s primary round was becoming progressively less effective against [music] the most modern Soviet tanks. The weapon that had been designed to kill a T62 [music] was facing armor that T62 technology could not anticipate. Had this armor development accelerated by 5 years, the wombat would have entered the 1970s already partially obsolete against its primary target.
The investment in Port Doctrine, the training of anti-tank platoon in a weapon system of genuine physical danger, the acceptance of the magnesium fire [music] risk as a necessary cost, all of it would have been built around a round that could not reliably complete its mission. The Milan missile that eventually replaced the wombat was already in development.
An earlier composite armor threat might have accelerated that transition and avoided the years in which crews were operating a weapon of questionable effectiveness against its intended target while being told it remained viable. The wombat’s operational window was real but narrower than its service life suggests.
It was the right weapon for its threat environment. The threat environment changed and the weapon did not change with it. That [music] is not a failure of the wombat’s design. The design was fixed and the physics of HESH are what they are. It is an illustration of the speed at which Cold War armor development moved and the institutional difficulty of retiring a weapon that is still capable of killing yesterday’s tanks when today’s tanks have become the problem.
The wombat was retired in the early 1980s, replaced by the Milan wireg guided missile system. The contrast between the two weapons is a study in how anti-tank philosophy changed across two decades. Milan could engage targets at over 2,000 m, four times the wombat’s effective range. It produced almost no back blast signature.
It used a guidance wire to steer the missile to the target, removing the need for the ballistic matching of a spotting round. It had no magnesium fire risk. It weighed less than the wombat and required a smaller crew. On every measurable technical parameter, Milan was the superior system. What it could not do was fire canister rounds against massed infantry.
It could not fire smoke for concealment. It could not be repurposed as the generalpurposeheavy weapon of an anti-tank platoon commander who needed more than one answer to more than one problem. The wombat was the last of the battalion guns, a weapon that gave the infantry commander something close to his own personal artillery piece.
Milan was a specialist tool. The wombat had been a general purpose one. The transition to missile systems made British anti-tank platoon more capable against armor and less flexible [music] against everything else. Wombat survivors are relatively rare in public collections given the weapon’s nature. A large recoilless rifle made of a material that corrods and cracks in poor storage conditions is not an easy artifact to preserve.
The Royal Artillery Museum at Woolitch held examples during its operational period and the collection has since been partially integrated into the firepower museum documentation. The Airborne Assault Museum at Duxford, home of three PAR’s history, holds material covering the wombat service with the paratroopers, including the Port Doctrine and the training records from the North German plane exercises.
History
The Imperial War Museum holds photographic and documentary records of the weapon in its Cold War context. Several deactivated wombat examples [music] have passed through military surplus auctions in the United Kingdom over the years. Though the condition of the electron barrels on many of these is a matter of concern for collectors who understand the stress corrosion [music] cracking problem.
A wombat barrel that has not been stored correctly and regularly inspected should be treated as a structural unknown. The physics of magnesium under stress do not become less relevant because the weapon has been deactivated. The wombat [music] was what happens when an army that cannot afford to be outgunned decides to outthink the problem instead.
The recoilless principle [music] was not new in the 1950s, but the application of that principle to a weapon of this caliber [music] mounted on a material of this risk operated by a three-man team from the back of a stripped Land Rover against the most heavily armored threat the Cold War was producing. That specific combination of physics and engineering and tactical imagination was entirely British.
[music] It was extreme. It was dangerous. It worked. The crews who operated it understood the bargain they had accepted, mobility in [music] exchange for vulnerability, lethality in exchange for the knowledge that the weapon itself [music] required as much respect as the target it was aimed at.The veteran accounts at the IWM are consistent on one point above all others. You maintained the wombat perfectly or you did not want to be near it when someone pulled the lanyard. The wombat never fired around in the war it was designed for. The masked Soviet armor crossing the [music] North German plane never came.
What the weapon left behind is a specific lesson about what cold war British engineering was willing to accept in pursuit of a capability that conventional design could not provide. It pushed the recoilless principle further than anyone had pushed it before in a material that no one else was willing to use for a tactical problem that no heavier gun could solve.
[music] That is the unvarnished truth of the wombat. Not that it was safe, that it was necessary, and that the men who operated it made that necessity work. Now it’s time for my favorite part where we get to hear from you. To the veterans who operated the wombat in anti-tank platoon, on porte Land Rovers, on the North German plane, or anywhere else the Cold War took you, tell us what the official briefings left [music] out.Tell us what it actually felt like to pull that lanyard and whether the back blast discipline was as absolute in a real engagement as it was on exercise. And tell us honestly whether you trusted the electron barrel or whether the magnesium risk was something you managed by never quite thinking about it directly.
And for the engineers and historians in the community, the wombat [music] represents a specific moment when a weight requirement overrode a material safety concern at the institutional level. Tell us whether you think that decision was justified by the tactical capability it produced or whether there was a safer engineering path that was available and not taken.
The spotting rifle as a ballistic computer is also worth your analysis. Was it the smartest low technology solution in Cold War infantry weapons or a dependency that should have been designed out from the beginning? Your knowledge and your stories are what makes Timeless Arms the home of the unvarnished truth.
If this video gave you something, share it with someone who needs to hear it. Subscribe if you haven’t already, and we will see you in the next one. Until next time, this is Timeless Arms.