BMW Built A Radial Engine So Good It Made The Spitfire Obsolete Overnight

[00:00:00]In September 1941, a new fighter appeared over the French coast and within weeks the best pilots in the Royal Air Force were being beaten by an engine they had been taught was a mistake. It was a radial. Fat, air-cooled, blunt at the front. The exact shape every fighter designer had crossed off the list because a radial engine punched a wide hole in the air and a wide hole in the air meant drag and drag meant a slow fighter.

[00:00:34]Everyone knew this. The Spitfire had a slim, liquid-cooled 12-cylinder engine for a reason.

[00:00:42]And yet here was a German machine with a great round radial in its nose and it was faster than the Spitfire, climbed better than the Spitfire, dived away from the Spitfire, and rolled in a way no Spitfire pilot could follow.

[00:00:59]There was a second thing the British pilots could not see from the cockpit and it mattered just as much.

[00:01:06]The German flying that fighter was doing less work than they were.

[00:01:10]He pushed one lever forward and the engine worked out the rest.

[00:01:15]His opponent was still managing his mixture, his supercharger, and his boost by hand and by feel in the middle of a fight for his life.

[00:01:25]One lever against many.

[00:01:28]Remember that because the whole story turns on it.

[00:01:32]This is Machine Titans where we pull apart the machines that bent history and show you what was really inside them.

[00:01:42]If that is your kind of thing, take a second and subscribe before you go. So, how did a radial engine, the wrong engine, make the most famous fighter of the war look obsolete for a year?

[00:01:57]And why did it last only a year?

[00:02:00]To understand that, you have to start with an idea that in 1938, almost everyone thought was a waste of time.

[00:02:10]The engine in the nose of that fighter was the BMW 801, and BMW did not begin as a builder of great radials. It began as a borrower of one.

[00:02:23]In 1929, the company bought a license to build the American Pratt & Whitney Hornet, a nine-cylinder radial, under its own name.

[00:02:33]From that bought design, BMW grew its own line, the BMW 132, the engine that hauled the Junkers 52 trimotor across Europe. That was respectable work. It was not glory.

[00:02:49]BMW was building other people's ideas a little better than the originals.

[00:02:55]The leap came from a fighter program nobody expected to matter.

[00:02:59]In the autumn of 1937, the German Air Ministry asked Focke-Wulf to design a new fighter to sit alongside the Messerschmitt 109, which was already the backbone of the Luftwaffe.

[00:03:13]The man who took the job was Kurt Tank, the technical director at Focke-Wulf.

[00:03:19]And Tank made a choice that his peers thought was close to professional suicide.

[00:03:24]He chose a radial.

[00:03:27]The orthodoxy of the day was absolute.

[00:03:30]Frontline fighters used slim inline engines because a fighter lives and dies on speed, and a radial's broad face was a brick wall to the airflow.

[00:03:42]The British built the Spitfire around the inline Rolls-Royce Merlin. The Germans built the Messerschmitt 109 around the inline Daimler-Benz.

[00:03:52]Tank looked at all of that and bet that a radial could be wrapped tightly enough and cooled cleverly enough to keep its power without paying the full price in drag.

[00:04:03]He was betting against the entire room.

[00:04:06]His first engine for the job was the BMW 139, an experimental 18-cylinder radial making around 1,550 horsepower.

[00:04:17]The first prototype flew on the 1st of June, 1939.

[00:04:22]It was fast. It also cooked itself.

[00:04:25]The tightly ducted nose that made it slippery choked the airflow the cylinders needed, and the engine ran hot enough to roast the pilot's feet.

[00:04:35]The 139 was a dead end. So, BMW handed Tank the engine that would change everything, the 801, a 14-cylinder twin-row radial of 41.8 L, and Focke-Wulf solved the cooling with a brutal piece of practicality, a forced-draft fan mounted right behind the propeller that rammed air over the cylinders whether the aircraft was moving fast or not.

[00:05:02]The radial would breathe after all.

[00:05:05]But, the genius of the 801 was not in the cylinders. It was in a box of gears and oil bolted behind them, and that box is where this story really lives.

[00:05:18]The box was called the Kommandogerät, which translates roughly as the command device, and it did something no other combat engine of its generation could do.

[00:05:29]A high-performance piston engine is not one machine. It is half a dozen machines that all have to be tuned to each other second by second as the aircraft changes speed and height, propeller pitch, fuel mixture, supercharger gear, ignition timing, engine speed.

[00:05:50]On a Spitfire, the pilot carried a share of that mental load himself, watching his gauges, setting his mixture, working his boost, choosing the right supercharger gear at the right altitude, all while trying to put bullets into another aircraft that was trying very hard to kill him.

[00:06:11]Every one of those adjustments was a small tax on his attention. And attention was the one thing a fighter pilot could never spare.

[00:06:19]The Kommandogerät paid that tax for the German pilot.

[00:06:24]It was a mechanical and hydraulic brain that read the throttle position and the altitude and then set the mixture, the propeller pitch, the supercharger, the timing, and the engine speed automatically. All of them. All at once.

[00:06:40]All correct.

[00:06:42]The pilot pushed the throttle. The brain did the thinking.

[00:06:47]One lever. Walk that out into a dog fight and you see what it bought.

[00:06:53]When a Spitfire pilot firewalled his engine in a sudden climb, part of his mind had to go to managing the engine through the change.

[00:07:01]When a Focke-Wulf pilot did the same thing, all of his mind stayed on the fight. He could throw the throttle around violently, slam from full power to idle and back, dive and climb and roll, and never once worry that he was about to over-rev the engine or lean the mixture out at the worst possible moment.

[00:07:22]The machine protected itself.

[00:07:25]That freed the pilot to fly closer to the edge than his enemy dared because his enemy was flying with one hand on the controls and one eye on the dials.

[00:07:35]This was the moat, and it was a strange kind of moat because it was invisible.

[00:07:41]You could not see it in a photograph of the aircraft.

[00:07:45]The Rolls-Royce Merlin was in most respects a magnificent engine, more refined, better at altitude, the heart of the Spitfire, and later of the American Mustang.

[00:07:56]The rivalry between Merlin and BMW was not really about horsepower. It was about who had to think.

[00:08:04]The Merlin asked the pilot to be a second engineer in the cockpit.

[00:08:09]The 801 asked him to be a pilot and nothing else. Some German pilots actually grumbled that the Kommandogerät was more trouble than it was worth, that they would rather control the engine themselves.

[00:08:22]They were wrong, and the men they were shooting down were the proof.

[00:08:26]On paper, this was a clever idea.

[00:08:30]Over the English Channel in the autumn of 1941, it became a slaughter.

[00:08:36]The Germans named the new fighter the Würger, the shrike, a small bird that impales its prey on thorns. British pilots learned the name the hard way.

[00:08:48]The Focke-Wulf went operational with Jagdgeschwader 26, the unit the Royal Air Force nicknamed the Abbeville Boys, in exactly the stretch of sky where Fighter Command was running its daylight sweeps over occupied France.

[00:09:05]Those sweeps had been designed to bleed the Luftwaffe through attrition.

[00:09:09]Instead, they became a proving ground for the new German fighter, and the proving went badly for Britain.

[00:09:17]The numbers were not close.

[00:09:19]When the Royal Air Force finally got a captured example onto its own test field, the report was blunt, and it gave little comfort.

[00:09:28]The Focke-Wulf 190 was faster than the current Spitfire, the Mark V, by 25 to 35 mph at every height that mattered.

[00:09:40]It out-climbed the Spitfire. It out-dived the Spitfire so easily that a British pilot who tried to chase one downhill simply watched it shrink into the distance.

[00:09:51]And its rate of roll was in a different class. So, a Focke-Wulf pilot could flick into a rolling turn and reverse his direction before the Spitfire had even started to follow.

[00:10:03]The one thing the Spitfire could still do better was turn tightly in a sustained circle. And a single advantage is a thin thing to stake your life on when the other aircraft is better at everything else.

[00:10:16]What made it worse was that the Spitfire Mark V had itself been a rushed answer. It was an emergency fix. An existing airframe given a more powerful Merlin to claw back the lead the F model Messerschmitt 109 had taken.

[00:10:34]Now, the emergency fix was the front-line fighter, and it was outclassed again, this time by something that beat it on almost every axis at once.

[00:10:44]It was a strange reversal.

[00:10:47]In the summer of 1940, over this same stretch of water, the Royal Air Force had held the better hand. Now, the Germans did, and for the first time in a long while their pilots climbed into a fight trusting that the machine, not just the man, would carry them home.

[00:11:06]The Focke-Wulf was everywhere that year, and it was good at everything.

[00:11:11]In February of 1942, during the Channel Dash, when the German battlecruisers Scharnhorst and Gneisenau ran straight up the English Channel in daylight under the noses of the British, it was Focke-Wulfs holding the air over them.

[00:11:27]Through the spring, they screamed in low over with southern English coast in fast tip-and-run raids that the defenders could barely intercept. And in August of 1942, over the disastrous Allied landing at Dieppe, more than 100 Focke-Wulfs from Jagdgeschwader 2 and Jagdgeschwader 26 tore into the air battle and claimed 61 Allied aircraft shot down for the loss of 25 of their own. The 801 became the most produced radial engine Germany ever built, more than 60,000 of them by most accounts. And for about a year, it owned the sky over the Channel.

[00:12:09]But the engine had one altitude it quietly hated, and the British were about to find out exactly why.

[00:12:17]The flaw was in the thin air.

[00:12:19]German supercharger technology lagged behind British, and a supercharger is the thing that lets an engine keep making power as the air gets thin with height.

[00:12:30]Low down and in the middle altitudes, where most of the Channel fighting happened, the 801 was a monster.

[00:12:38]Take it up high, and its breath grew short.

[00:12:41]That weakness was real, but the British did not yet know how to exploit it because they had never had an intact Focke-Wulf 190 to take apart and measure.

[00:12:52]They wanted one so badly that Fighter Command had begun seriously planning a commando raid on a French airfield to steal one.

[00:13:01]Then, on the 23rd of June 1942, the war handed them a gift so absurd that no planner would have dared put it on paper.

[00:13:11]His name was Armin Faber, an Oberleutnant flying with the German second fighter wing out of Morlaix in Brittany.

[00:13:20]That day, Faber got into a hard dogfight over southern England, shot down a Spitfire, and came out of the fight rattled and turned around.

[00:13:30]He was low on fuel. He saw water beneath him and a coastline ahead, and he decided he was crossing the English Channel back toward friendly France.

[00:13:40]He was not.

[00:13:41]He was crossing the Bristol Channel and the land ahead of him was Wales.

[00:13:47]He found an airfield, an airbase called Pembury, home of the air gunnery school, waggled his wings in a little victory celebration, dropped his undercarriage, and landed his Focke-Wulf neatly on a Royal Air Force base.

[00:14:04]The duty pilot grabbed a flare gun, ran out, and jumped onto the wing before Faber understood what he had done.

[00:14:11]It was the first Focke-Wulf 190 to fall into Allied hands completely intact.

[00:14:19]The British repainted it, gave it a British serial number MP499, and flew it again and again in direct comparison against their own fighters, learning its strengths exactly and its weaknesses exactly.

[00:14:35]The aircraft that had been a mystery was now an open book, and the people reading that book already had the answer waiting on a workbench in Derby.

[00:14:45]The answer was the Spitfire Mark IX.

[00:14:48]Rolls-Royce had taken the Merlin and given it a new two-stage, two-speed supercharger, the very thing the German engine lacked, and the result was a Spitfire that finally kept its power up high where the 801 ran out of breath.

[00:15:05]The Mark IX reached squadrons from the middle of 1942, and the year of German dominance ended almost as quickly as it had begun.

[00:15:15]The performance gap closed. Parity returned, and from there the trend ran one way because the allies could improve and replace their designs faster than Germany could, and the Spitfire kept getting new and better engines all the way up to the big Rolls-Royce Griffin, staying competitive until the last day of the war.

[00:15:39]The deepest irony came for the Focke-Wulf itself.

[00:15:43]The radial that had beaten the Spitfire by being a radial could not solve its own altitude problem as a radial.

[00:15:51]To make a high-flying Focke-Wulf that could match the newest Allied fighters, Kurt Tank eventually had to do the one thing his whole gamble had been built to avoid.

[00:16:02]He took the radial out.

[00:16:04]The later Focke-Wulf 190D, the long-nosed Dora that pilots loved, carried an inline Junkers Jumo engine in its nose, the same slim shape Tank had bet against in 1938.

[00:16:19]The engine that won the year was, in the end, set aside to win the altitude.

[00:16:25]So, what was it all worth?

[00:16:27]The Spitfire it had humbled outlived it completely, soldiering on in production until 1948, long after the last 801 fell silent.

[00:16:39]The radial won the year and lost the decade.

[00:16:43]That is the honest verdict, and it would be a small and slightly sad place to end, except that the most important thing the 801 ever did was not shooting down Spitfires at all. It was that one lever.

[00:16:58]Think about what the Kommandogerät actually was.

[00:17:02]It was a machine that took a single human input and translated it instantly and automatically into the dozen precise adjustments a complicated engine needs to run at its best.

[00:17:15]The pilot stated his intention. The engine figured out how to deliver it.

[00:17:20]In the 1980s, the engineers at Porsche built an aircraft engine derived from their 911 sports car that you flew with one control, reinventing the same single lever idea apparently without realizing how thoroughly it had already been done four decades earlier.

[00:17:39]And the principle underneath it that you give the engine one command and the engine works out everything else for itself is the exact principle that governs the engine in almost every car on the road today.

[00:17:53]The throttle you press is a request.

[00:17:56]A computer reads it and sets your fuel, your timing, your boost, your mixture, all of it hundreds of times a second so you never have to think about any of it.

[00:18:08]One lever, the machine does the thinking. The Germans built the first engine brain that could take a single command and run an entire engine from it out of gears and oil and bolted it behind a radial in 1941.

[00:18:24]The same idea is still running in a far smarter form under the hood of whatever you drove today. Quite possibly under the hood of a BMW.

[00:18:35]As for Armin Faber, the man whose wrong turn over the Bristol Channel handed Britain the secret it had been planning a commando raid to steal, he spent the rest of the war in a prisoner of war camp remembered forever for the single worst piece of navigation and the single greatest accidental gift of his entire life.

[00:18:58]If you want to see engineers make the exact opposite bet, an inline engine pushed to the absolute edge of what was possible, the Kestrel is the one to watch next. And if you made it this far, you already know the drill. Like the video, subscribe, and I will see you in the next one.