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This is the M1A2 Abrams, the US Army's Main Battle Tank and one of the most advanced armored vehicles in the world. It's armed with a cannon over 5 meters long that can punch through nearly a meter of steel from two kilometers away. Depleted uranium plates protect its turret and hull. The latest upgrades added an additional anti-mine underplate, reactive armor tiles over the flanks and a TROPHY active protection system on top, but these raise the Abrams' fully loaded combat weight to 78 tons. That's as much as a Boeing 737-800 on takeoff, or twenty Ford F-450s stacked on top of each other.
Yet here it is racing down dirt roads at highway speeds. Jumping and firing mid-air. Wading through meter-deep mud, and drifting it like it's aToyota AE86. And it's possible thanks to this. Its powertrain is a jet engine attached to a gearbox taken from a helicopter, capable of generating 1500 horsepower out of any fuel from gasoline to vegetable oil, with enough torque to accelerate an Abrams to half its top speed in 6 seconds. No other tank today, bar one, uses something like this. But the amount of fuel it consumes is the Abrams' biggest handicap, turning into a logistical nightmare when fighting in Ukraine.
It can't travel as far or sortie as often as other tanks because of a turbine it wasn't even supposed to have and that the US Army is going to ditch this year. Out of 31 A1 Abram tanks delivered to Ukraine, 27 have been lost. How did the Abrams end up like this, and why did it fail? To explain this we have to follow the incredible evolution of tank engines going back a hundred years. Designing a tank engine is an exercise in managing contradictions. Tanks want to install as much armor and firepower as possible, which comes with the cost of a lot of weight. To move all that, the engine needs a lot of torque,
specifically low end torque. Torque that's available at low engine RPMS, when the tank is just beginning to move and has the most inertia to overcome. The easiest way to do that is to increase engine displacement. Larger piston cylinders hold bigger explosions, raising the twisting force at the crankshaft. But an engine like this takes up more space within a tank hull, which means a bigger hull with more area to cover with heavy armor, which then needs a bigger engine to move around. We're back at square one.
There were no specialized tank engines to solve that problem in world war 1, when tanks first saw combat. These were secretive emergency projects designed with what was available. The British Mark I and the French Saint-Chamond trapped eight men in a closed box with a carbon monoxide-fuming tractor engine that barely managed 100 horsepower while rattling their ears off or burning them with exposed red-hot exhaust pipes. They only managed to crawl over trenches at a mere walking pace. Tank evolution really began to accelerate in World War II. Early engagements between Allied and Axis forces quickly revealed that the US Army's 18 ton M2 Medium tank
was beyond obsolete. It didn't have the armor to stand up to German 75mm guns nor the weapons to defeat Panzers from any range. So, engineers rushed to create a tank with heavier armor and its own 75mm gun. The result was the slapdash M3 Lee, with its main gun jammed into its side, later perfected into the war-winning M4 Sherman. The Sherman was around 30 tons to 33 tons depending on the variant. Why not more, like the British designed Churchills? The US Army had been trialling heavy tanks of their own but they could never fit into the Allied logistics chain. American forces needed to cross oceans before they
could fight on the battlefields of Europe, Africa or Asia. That meant any tanks they brought with them had to be easily shipped and deployed by the equipment at hand. The Liberty Ship, backbone of Allied logistics, used cargo hoists that usually couldn't handle more than 30 tons. The landing craft which brought tanks ashore, like the LCM-3 during D-Day, could only carry a single 30 ton load. Prefabricated Bailey Bridges for crossing rivers in enemy territory also imposed their own size and weight restrictions. It made no sense to build a super tank that would never reach the battlefield.
The choice of engine for the M4 Sherman was similarly practical. It started with the 340 horsepower Wright-Continental R975, a lightweight 9-cylinder radial engine that was robust, reliable and most importantly already in mass production. Later versions bundled together whatever engines that were available just to keep up with demand from the front line. But other variants experimented with engine arrangements looking for the perfect formula, like M4A4, which came with FIVE Chrysler inline v6 engines all driving their power to a single driveshaft. Combining to create a 370 horsepower, 20.5 litre displacement,
30 cylinder multibank contraption called the A57. Chrysler even claimed in a 1944 issue of Popular Science that the tank could keep moving with 2 of its 5 engines knocked out. The Germans didn't have such strict logistical restrictions on their tanks. Their tanks could ride trains with multi-axle flatcars, and then just drive the rest of the way to the front under their own power. The result was a number of designs with superior guns and armor two to three times thicker than any Allied vehicle. The infamous Tiger I was a 54 ton box with 10 centimeters of steel over the front,
impervious to the Sherman. When the Allies brought in bigger guns to deal with the Tiger I, the Germans developed its successor, the 68 ton Tiger II with 15 cm of slopped armor, which made the effective armor thickness 23 centimeters. In the last year of the war, the 72 ton Jagdtiger appeared, with 25 centimeters of armor and a massive 128mm gun that could knock out Shermans from over 3 kilometers away. To deal with the ever increasing weight, the Germans simply used the same Maybach V12 liquid cooled engine, and scaled up its displacement.
The first Tigers to roll off the manufacturing line came with an inadequate 21 litre engine (HL210). To upgrade it they simply increased its cylinder bore by 5 mm to create a 23 litre displacement engine (HL230). At 700 horsepower it was still not enough. One of the best engines in the war, stretched to its limit by ever increasing weight. It gave the Tiger a power to weight ratio of around 12-13 horsepower per tonne, then they threw it into the 72 tonne Jagdtiger. The Germans had completely lost the run of themselves at this point. This engine was completely overstressed, and their tanks were more frequently abandoned and destroyed by their crews when something broke than destroyed by enemy fire.
Throughout the war, the Soviets took the brunt of Axis aggression and they learned hard lessons on how important it was to balance offense, defence and mobility, and used them to design the T-44. Their genius idea was to take the engine of the T-34 tank, the most prolific military V12 diesel in history, and simply turn it 90 degrees and package it with its transmission in a compact bay in the rear. This lowered the height of the hull by around 30 centimetres, not just making it a smaller target, but allowed for critical weight to be shifted to front armor where it was needed most, while creating room for a wide turret that could hold a
high-caliber gun, granting the T-44 the firepower and protection of a tank twice its weight. While it didn't get a notable service record and was soon replaced, we can trace the compact design and hull layout of all Russian tanks today back to the T-44. What followed was a period of relative stagnation. The Cold War meant that tank development continued, but without technological breakthroughs the improvements were just incremental. In the mid-1960s however, tank design philosophy shifted radically. Finding targets and devising a firing solution had been considerably sped up by the introduction of advanced optics, rangefinders and stabilized barrels. High Explosive Anti-Tank ammunition and Armor Piercing Fin Stabilized Discarding Sabot rounds had been
developed into high velocity projectiles that could penetrate up to half a meter of steel, so no tank could carry enough armor to protect itself reliably. Combined, these features meant that tank combat devolved into a brawl where the first one to find and shoot their opponent almost always got the kill, and the only way to survive was to rapidly duck behind cover. The implication for tank design was that most armor could be discarded in favour of maximum maneuverability, which raised the importance of engine design even higher. West Germany met this design challenge with the Leopard 1, with a 10 cylinder supercharged 37 litre engine in 1965. It carried minimal armor and a stabilized 105mm
gun. The Leopard 1 weighed in at 40 tons despite its hull being over 8 meters long. Soviet tank design took another direction with their T-64A. They raised the stakes with a massive 125mm caliber cannon and developed an autoloader system to handle ammunition that exceeded 20 kg a piece. New composite armor called Combination K placed glass-reinforced plastic in between traditional steel plates, offering better protection than the same full thickness of steel at much loewe weight. They packaged it with an innovative powerplant design. A two stroke opposed 5 cylinder engine. With two pistons in each cylinder,
pushing towards each other. Eliminating heavy cylinder heads and valves. This resulted in an engine with twice the power density of the American's M60's Continental engine. The 38 ton T-64A entered service in 1967 as the most advanced Main Battle Tank in the world. But that came with a cost. The engine had to be driven perfectly to avoid damage. The gear train keeping everything running smoothly had its work cut out for it in a tank battling it out on rugged terrain. Heat is also concentrated in the centre of the two pistons, with no cylinder head, and without adequate cooling, the pistons could actually absorb enough heat to expand and seize within the cylinder. So, the T-64A was reserved for elite fighting units.
The most innovative high power density engine isn't always the best choice. Watching these developments, the US Army found itself at a crossroads. It could continue with incremental improvements of the M60, based on a hull with WWII heritage, or take a great leap forward to address present and future Soviet threats. It chose the latter path by investing in a joint venture with West Germany, in what would become the disastrous MBT-70 program. On paper, the idea was great. Two NATO allies, the US and West Germany, would combine their expertise
and share the costs of developing a revolutionary tank that would glide over the battlefield at 70 km/h on hydropneumatic suspension, out-ranging anything the Soviets had with a 152mm autoloaded gun that fired missiles, all while staying under 45 tons. In practice, it was a disaster, with neither side agreeing on anything from the choice of major components like the gun or engine, or even whether to use metric or imperial units. The US Army's attempt to salvage it later also failed, so after 7 years of effort and 11 billion dollars in today's money spent, no new tank was ready.
US restarted its search with a stricter budget and looser requirements. Chrysler and General Motors both made proposals that used a conventional 105mm gun and incorporated the latest NATO composite armor schemes. Their main distinction was in the choice of engine. The Chrysler proposal was what was to become the A1 Abrams, fitted with the AGT-1500 turbine on traditional torsion bar suspension. Chrysler knew this was a risky move. Jet engines had an uncertain reliability record, and an extreme thirst for fuel, even when idling. But they did offer notable advantages: they could burn a wider selection of fuels,
and take up less space than a diesel engine. Most importantly they could reach maximum torque output nearly instantly. If we look at the torque vs RPM curves of a turbine engine compared to a diesel engine, we see a massive gap all the way up to 2100 RPM, or 70% of the maximum output shaft speed. In the time it takes a diesel-powered tank to spin up, a turbine-powered one would already be moving behind cover. In the end, the Chrysler design won the contract. Tactical mobility in the Cold War era was deemed a sufficiently good argument and the higher fuel consumption wouldn't matter in the lightning quick battles NATO expected to have with the Soviet Union. While others claim Chrysler was chosen to save it from Bankruptcy.
And so development of the Abrams began in 1976, the first new MBT in America's arsenal in two decades. The Abrams had the best survivability and cross-country performance of any tank of its time, something it actually demonstrated in trials against the Leopard 2. Where it fell short in fire control, it made up for it with better crew experience. More comfortable and easier to operate. But that lead did not last for long. The Soviets entered their own turbine-powered tank into service in 1976 too. The T-80 used a purpose-built GTD-1000 turboshaft producing 1000 horsepower,
and used that excess power to move around a heavier 42 ton tank with enough armor to withstand Western 105mm guns. The Soviets valued the turbine's ability to start up in arctic temperatures of -40°C and keep running for longer between maintenance. The T-64s' complicated opposed piston engine struggled with both these issues. Soon after, the T-80B upgrade rolled out to face the M1 Abrams in 1980. It had 1100 horsepower, even thicker armor and the ability to fire missiles from its barrel on the move, with a 4 kilometre range. Two years later, reactive armor started being added to Soviet tanks to deal with shaped charge missiles.
Shaped charges consist of an explosive shaped with a hollow indentation, lined with a ductile metal. When the charge is detonated a pressure wave forms behind this metal liner, deforming it and accelerating the metal into a lance stream of particles. The shaped charge effectively creates a hypersonic projectile at point black range. [REF][7] It's highly effective at cutting through armor. Reactive armor works b y placing an explosive charge between two metal plates. When a jet from a shaped charge strikes the upper plate it detonates the inner explosive.
You may think this could damage the tank, but tank's lower armor is more than capable of dealing with the relatively blunt pressure formed by the reactive armor detonation. The outer plate then flies outwards to disrupt the incoming jet while the shockwave formed by the detonation also breaks up the stream of metal approaching the tank. The US Army responded with a comprehensive upgrade package. It got additional armor, including depleted uranium plates so dense they can break up sabot round darts, better fire control electronics
and the Rheinmetall 120mm gun the Germans wanted to give it since the failed joint venture back in the 70s. It became the M1A1, and would go on to dominate in wars in the Middle East. After the Soviet Union collapsed, the Russians kept designing better tanks. The lesson they learned from the T-80's service record was that turbines are much less reliable than expected, and consume unsustainable amounts of fuel. The turbine engine was also ten times as expensive as an equivalent diesel engine, a critical factor in their decision to never make a jet tank again.
Since then, from Sweden to China, all main battle tanks put into service have good old reliable, fuel efficient, easy to maintain turbodiesel engines. With one exception: the US kept its jet tank, with the M1A2 upgrade coming in 1995, followed by a System Enhancement Package every few years to keep it competitive. Each upgrade came with a hefty increase in weight and worsened fuel consumption. Unlike the rest of the world, the US military has an $850 billion and rising budget. It can afford to keep gas guzzling tanks full, and has a fleet of C-5 Galaxy cargo planes to haul them across continents, that would be an
entire air force in another country. The problem is that all this effort might be unnecessary. The M1 Abram was designed for a world that's long gone. Dashing between firing positions to fend off a deluge of Soviet tanks pouring into Europe for a few days before the bombs fell. Extreme mobility being the only way to survive tank combat was only true for a few years. As the latest Leopard 2A7 or the British Challenger 2 demonstrate, Modern sophisticated composite armor layer rubber, ceramic and metal, and can absorb hits that would penetrate over a meter of steel. A far cry from the 23 centimetres of the terrifying Tiger 2. recently involved crossing the deserts of Iraq and idling for
months in Afghanistan. In these conditions, a jet engine in a tank is a disadvantage. An Abrams tank consumes a liter of fuel to roll just 142 meters, a German Leopard can manage twice the distance. The Abrams could be fully fueled in the morning and running on fumes by the evening just by standing still. The Abrams is finally facing Russian tanks in Ukraine, but instead of epic battles between rolling columns of armor. Ukraine is preserving its equipment. It has used the fuel hungry Abrams in short skirmishes with hit and run tactics. And the losses are remarkable. Out of 31 tanks delivered, 27 have been lost. And except for a single case of a direct hit from a Russian T-72B3,
every other loss has been drone attacks, anti-tank missile, artillery and anti-tank mines. The Abrams simply isn't fit for the modern battlefield. Additional armor can solve some of those problems. The US Army is rushing to buy Top Attack Protection for its Abrams, sometimes referred to as cope cages, and new additions provide thickened belly armor and active protection systems. But these come at the cost of even more weight, beyond the 78 tons it already rolls around with. A major shift in the Abrams' design is needed.
The Russian's newest T-14 Armata offers a glimpse at the solution to all this. A remotely controlled gun sits in an unmanned turret, while the crew is moved entirely to an armored capsule in the hull. This drastically reduces the volume that has to be armored, cutting down overall size and weight. Powering it is a new 34.5 litre displacement 12N360 diesel engine producing 1500 horsepower from 12 cylinders arranged in an X-shape, an arrangement that allows it to be a lot more compact than the V12 diesels going back to the T-34. In an emergency, the boost pressure can be raised to deliver 2000 horsepower at the cost
of some damage to the engine. While this tank may never be produced in threatening numbers or even complete its full development, it is an important marker for where future tank design is going. Prototypes and proposals for replacing the Abrams have appeared over the years. Unmanned turrets, with enormous 140 mm guns, and space age experimental materials. What they shared was Cummins diesel engines producing just as much horsepower as the turbine engine while taking up 50% less space. The US Army seems to have finally shifted course. With hard lessons learned from the Ukraine war,
they have developed the M1E3. With the latest armor technology it aims to reduce weight to 60 tons. Powering it will be the Cummins ACE Advanced Combat Engine. An opposed-piston turbodiesel paired with an electric motor. This is a hybrid tank, the tank version of a Prius. It could cut fuel consumption in half, and give the tank the ability to sneak around in all electric stealth mode, or lie in wait with the diesel engine turned off, hidden from infrared sensors. Soon we will see if this will really be the next step in tank warfare. But we already know what the next step in poster technology is. It's displate. Now, I'm not gonna lie, I wasn't really sold on this sponsor straight away,
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