3rd December 1942, German pilot Hman Klaus Richter moved his Faka Wolf 190 fighter into position behind a group of American P47 Thunderbolt planes. The big American fighters looked slow and clumsy in the frozen sky. He pressed his radio button and laughed. Look at these fat American milk trucks.

Their engine was designed by some nobody the army didn’t even want. Let’s send them home crying. Before we dive in, make sure you’re subscribed. And every week we uh uncover the stories the world forgot. What RTOR didn’t know was that the nobody who designed that engine had already changed everything about War in the Sky. His name was Sam Herren.

He was born in Ireland and spent years working on aircraft engines in Britain before coming to America in 1921. He had big ideas about a new kind of engine, but the US Army Airore said no. Three different times between 1925 and 1932, they rejected him. They told him his designs were too complex and unproven for military service.

The army liked smooth, streamlined engines that looked elegant and European. Heron’s engine design looked ugly by comparison. It had 18 cylinders arranged in two rows sticking out like fat metal fingers in a circle. It looked more like a machine you’d find on a farm than in a fighter plane.

The fancy military men laughed at it. But in 1939, a company called Prattton Whitney decided to take a chance on Sam Herren. What came out of their factory would change the war. They called it the R2800 Double Wasp. This engine was a monster. It had 2,84 cubic in of displacement and produced 2,000 horsepower just during normal takeoff. When pilots pushed the emergency war power, it jumped past 2400 horsepower.

The whole engine weighed 2360 lb. It spun at 2,700 revolutions per minute. It drank the highest grade fuel available, 100 octane gasoline, and it drank it fast. Each of the 18 cylinders fired with incredible force. The engine needed 425 cubic feet of air blasted past its cooling fins every single second just to keep from melting itself.

This wasn’t a polite gentleman’s engine. This was raw American power turned into metal. But all that power meant nothing if American pilots kept dying while learning to fly it. Between January and March of 1943, 11 pilots were killed in training accidents with the early P47 Thunderbolts. The problem was simple. The Thunderbolt was heavy, really heavy, fully loaded with fuel and ammunition.

It weighed 14,000 lb. Young pilots who had trained on lighter, more nimble fighters tried to fight the same way in the Thunderbolt. They tried to turn and twist with enemy planes, but when you do that, you lose speed. You lose energy. And when a plane that heavy loses energy, that big Pratt and Whitney engine couldn’t always pull them out of the spin. Pilots died.

Then a colonel named Hub Zama figured it out. He completely changed how Americans would fight in the Thunderbolt. His orders were simple and brutal. Don’t turn. Don’t chase. Dive from 25,000 ft. Hit them at 450 mph. climb back to altitude on that beautiful engine and do it again. He called it energy fighting. Use the weight, use the speed, use that incredible engine that could pull you back up to high altitude while enemy fighters were still trying to catch their breath down low.

Zama drilled this into every pilot’s head with one perfect sentence that became legend. The jug doesn’t dance, it punches. The jug, that’s what pilots called the P47, short for juggernaut. a rolling, unstoppable force. And at the heart of that force was Sam Herren’s rejected engine. The one the army said would never work. April 17th, 1943.

Lieutenant Bob Johnson was flying his P47 on a mission over Bremen, Germany. He dove down through a formation of German Faka Wolf fighters. His eight machine guns tore through two German planes before a third German pilot got behind him. The German fired. 16 20 mm cannon shells smashed into Johnson’s Thunderbolt.

Big shells, explosive shells, the kind that blow liquid cooled engines apart in seconds. Metal peeled away from Johnson’s wings. Red hydraulic fluid sprayed across his cockpit window. His control stick went loose and sloppy in his hands. But the R2800 engine just kept running. Those 18 cylinders kept firing, kept turning, kept pulling.

A liquid cooled engine like the British Merlin or the American Allison would have been dead in 30 seconds from those hits. Coolant would have poured out. The engine would have seized up into a block of useless metal. But Heron’s radial engine didn’t need liquid coolant running through fragile tubes. It was air cooled, tough, simple, brutal.

Johnson nursed that crippled plane 200 m back to England. He had almost no control. He was flying on pure instinct and that hammering faithful engine. When he reached England, he couldn’t get his landing gear down. The hydraulics were shot, so he landed in a farmer’s field, belly down, metal screaming across the grass.

When Johnson climbed out, he was shaking, but alive. When mechanics came to examine the wreck, they counted the damage. 21 holes large enough to fit a man’s fist through. The double Wasp engine had taken three direct cannon hits. It had never stopped running. Not for one second. Word spread fast among American pilots. The jug could take it.

The jug would bring you home. And that changed everything about how men fought in the sky. When you know your plane can absorb punishment that would kill any other fighter, you fight differently. You get aggressive. You get confident. Fear starts to shift from your cockpit to theirs.

6 weeks after Bob Johnson barely survived that mission over Bremen, he was back in the sky over the Roar Valley in Germany. This time he wasn’t running. This time he was hunting. Johnson spotted a German FWolf 190 making a slow, lazy climbing turn at 12,000 ft. It was the kind of arrogant move German pilots made when they thought they owned the sky.

When they thought no American plane could touch them up there. Johnson smiled inside his oxygen mask. He rolled his thunderbolt inverted, pulled the nose down toward the earth, and let gravity do its work. 7 tons of American fighter started falling. But it wasn’t just falling. That R2800 engine was pushing out 2400 horsepower, adding power to gravity’s pull.

The airspeed indicator wound up like a clock gone mad. 400 mph, 420, 450. 475 Johnson’s 850 caliber machine guns were loaded and ready. Each gun could fire 850 rounds per minute. Together, they could put out 6,800 bullets every 60 seconds. At 300 yd, Johnson squeezed the trigger. The convergence point, the place where all eight streams of armor-piercing incendiary bullets met in one tight cone of destruction, hit the Faulk Wolf exactly where Johnson aimed.

The German plane’s left wing just exploded. Not broke, not damaged, exploded, ripped completely off the fuselage. The Faka Wolf tumbled out of the sky like a broken toy. Johnson later said, “It just exploded. I’d never seen anything like it.” On his radio, he heard a German voice sharp and angry and scared. Unmug.

Impossible. That pig is too heavy to do that. Then nothing but static. The Germans were learning a hard lesson. The P-47 wasn’t a dog fighter. It was a killer. And at the heart of that killer was an engine that just would not quit. By the summer of 1943, stories like Johnson’s were spreading through both sides of the war.

American pilots were gaining confidence with every mission. German pilots were starting to feel something they hadn’t felt before in the war. Doubt. But Pratt and Whitney and Republic Aviation weren’t done improving the engine and the plane. In August 1943, they introduced a major upgrade. They installed a new turbocharger called the CH5.

A turbocharger takes exhaust gases from the engine and uses them to compress the incoming air, which means the engine can breathe better at high altitude where the air is thin. This new turbocharger was a masterpiece. It could maintain full engine power all the way up to 30,000 ft. Most engines wheezed and struggled at that altitude.

The upgraded R2800 just kept punching. They also added something called water injection. Pilots could push a button and inject a mixture of water and methanol directly into the engine for short bursts. This cooled the combustion chambers and let the engine run even harder without destroying itself. With water injection engaged, the R2800 could produce 2535 horsepower.

For reference, that’s more power than three modern family cars combined coming from one 1940s aircraft engine. The propeller tips were spinning so fast they actually broke the sound barrier, going supersonic at the very edges. This created a distinctive cracking booming sound that ground crews started calling the thunderclap. When a P47 pilot pushed that water injection button and opened the throttle, the plane didn’t just accelerate, it detonated forward.

Pilot said it felt like getting kicked in the back by a mule. You got shoved back into your seat so hard it hurt. Then came one of the most important innovations of the air war, drop tanks. These were large external fuel tanks that could be attached under the wings. Each tank held 150 g of gasoline. With two drop tanks installed, the P47 could carry enough fuel to escort bomber formations all the way to Berlin and back.

That was 930 mi each way, 1,60 mi total. Before drop tanks, the Thunderbolt could only go about 475 mi before it had to turn back. Enemy fighters learned this. They would wait just beyond the P-47’s range, then attack the unescorted bombers. But with drop tanks, that safety zone disappeared. Suddenly, American fighters could go anywhere the bombers went.

The P-47’s role completely changed. It went from being a short-range defensive interceptor to a long range offensive weapon. Thunderbolt started flying deep into Germany, shooting down enemy fighters over their own airfields, strafing trains and trucks, attacking ground targets. The enemy had nowhere to hide.

The impact on German morale was devastating. Luftwafa pilot Hans Phillip, who had shot down over 200 Allied planes on the Eastern Front, wrote in his diary after encountering P-47s in late 1943, “We are confronted with an enemy who is superior in numbers and material. The Americans replace their losses overnight. We cannot. Their pilots are becoming skilled.

Their machines are nearly indestructible. I have put more than 100 rounds into a Thunderbolt and watched it fly home. This is not the same war we fought in 1940. Another German pilot interrogated after being shot down in early 1944 was asked what he feared most in the sky. His answer was simple.

The jug, you cannot kill it. You cannot outrun it. You cannot hide from it. It is always there, always above you, waiting to dive. The Japanese had their own reckoning with Sam Herren’s engine, though not in the P-47. The R2800 also powered the F6F Hellcat fighter and the F4U Corsair, two Navy planes that dominated the Pacific.

Japanese pilots who had terrorized the Pacific in 1941 and 1942 with their nimble Zero fighters found themselves facing American planes that were faster, tougher, and more heavily armed. The Zero was light and maneuverable, but its light construction made it fragile. One good burst would tear it apart. Meanwhile, the R2800 powered American fighters could absorb incredible damage.

Japanese ace Saburro Sakai, one of the few who survived the war, wrote after, “We learned to fear the sound of that engine. It was deeper, heavier than our engines. When you heard that sound above you, death was coming.” The industrial side of this story is where America’s true power showed itself.

Pratt and Whitney didn’t just build a good engine. They built tens of thousands of them. By 1944, Prattton Whitney’s factories were producing 3,000 R2800 engines every single month. That’s 100 engines per day, every single day. The engines were being installed in P47 Thunderbolts, F6F Hellcats, F4U Corsair’s, A26 Invaders, B26 Marauders, and C-46 transport planes. The R2800 was everywhere.

Compare that to Germany. The Germans had excellent engines like the Dameler Benz DB 605 that powered their late war fighters. But German production was chaos. Factories were being bombed constantly. Raw materials were running short. Skilled workers were being drafted into the army. In 1944, Germany produced about 39,000 aircraft engines total, all types combined.

America produced over 250,000 engines that same year, and American factories were safe. Thousands of miles from any enemy bomber. The math was brutal and simple. If Germany lost 10 pilots and 10 planes in a day of fighting, it might take them 2 weeks to replace those losses, maybe longer.

If America lost 10 pilots and 10 planes, they were replaced in 48 hours. Fresh pilots were coming out of training schools in Texas, Arizona, and Florida by the hundreds. New planes were rolling off assembly lines in Long Island, Connecticut, and California by the dozens per day. The United States wasn’t fighting a war. It was running an industrial machine that produced victory like a factory produces cars.

This brings us to the final boss moment of Sam Herren’s engine story, facing the German jets. In late 1944, Germany introduced the Messersmid Mi262, the world’s first operational jet fighter. It was fast, over 540 mph in level flight. No Allied propeller plane could catch it in a straight line. German propaganda made bold claims.

The Mi262 will sweep the Americans from our skies. For a few weeks, it seemed possible. American bomber crews reported being attacked by fighters moving at impossible speeds, diving through their formations, gone before anyone could react. But the Mi262 had a critical weakness, and American pilots found it quickly.

Jets in 1944 were primitive and unreliable. They drank fuel at an incredible rate, and MI262 could only stay in the air for about an hour before it had to land and refuel. And when it landed, when it slowed down to approach the runway, it was vulnerable. It was just another plane slower than a P-47 in landing configuration.

American fighter pilots started camping near known ME262 bases. They would orbit at high altitude, waiting. When a German jet came back from a mission low on fuel, focused on getting down safely, the P-47s would pounce, diving from altitude with that massive R2800 engine howling. They could reach speeds competitive with the jet in a dive.

More importantly, the P47’s 850 caliber guns didn’t need to catch the jet in flight. They just needed to catch it in those vulnerable 30 seconds on final approach. Colonel Hub Zama, the same man who had figured out how to fight in the P-47 back in 1943, shot down an ME262 exactly this way in October 1944. He described it in his mission report.

Observed enemy jet aircraft on approach to Ammer airfield at approximately 200 ft altitude, low air speed, rolled inverted, dove from 15,000 ft, intercepted at 450 men, closure rate, opened fire at 400 yd. Enemy aircraft exploded on impact with ground. Pilot did not eject. Clean, professional, brutal.

Operation Bowden Plata in January 1945 showed just how completely the tide had turned. The Luftwaffa launched a massive surprise attack on Allied airfields in Belgium and the Netherlands on New Year’s Day. They threw nearly 900 aircraft into the assault, one of their largest operations of the entire war. It was supposed to be a knockout blow, a way to destroy Allied air power on the ground.

Initially, it worked. Hundreds of Allied planes were destroyed or damaged while parked on airfields, but then the American fighters got airborne. P47 Thunderbolts along with P-51 Mustangs and British Spitfires tore into the German formations. The Luftwaffa lost over 300 aircraft that day. Worst, they lost 237 pilots, including many experienced squadron and group commanders.

These were men who couldn’t be replaced. Germany no longer had the fuel to train new pilots properly. Meanwhile, the Americans counted their losses, filed the reports, and waited. Replacement aircraft arrived within 72 hours. Replacement pilots arrived within a week. The operational tempo never slowed down.

A German pilot who survived Bowden Plata and was captured 3 weeks later said during interrogation, “We knew it was over after that day. We threw everything we had at them, caught them by surprise, destroyed hundreds of their aircraft, and it didn’t matter. 3 days later, they had more planes than before. Their factories are untouchable.

Their pilots keep coming. We are fighting a country that can lose and lose and lose and just keep getting stronger. How do you win against that?