212: Leaves Upon the Wind

Description

This episode dives deep into the often-overlooked details of the Battle of Britain, going beyond the famous aircraft to explore the technological and logistical factors that impacted the fighting. We examine the strengths and weaknesses of aircraft like the Defiant, the crucial role of high-octane fuel in providing a performance edge, and even how seemingly minor details could influence the outcome of aerial engagements. From the limitations of turret fighters to the impact of fuel quality on climb rates, this episode reveals the complex web of factors that shaped the air war over Britain, setting the stage for a future discussion of the pilots who fought it.

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Transcript

Summary

Hello everyone and welcome to History of the Second World War Episode 212 - The Battle Before Britain Pt. 4 - Leaves Upon the Wind. This week a big thank you goes out to Joshua, Lee, Alex, and Bennett for choosing to support the podcast by becoming members, you can find out more about supporting the podcast over at historyofthesecondworldwar.com/members. The first three episodes of this series have discussed technology and strategy built around that technology, and this will be the fourth episode on that theme. Of course we cannot complete a discussion of the technology and tactics that would be on display over France and Britain in 1940 without taking some time to discuss the aircraft that would be locked in combat in the skies. There were of course the three big fighters: Bf-109, Hurricane, and Spitfire but there were of course many other types of aircraft involved in the campaign, from German bombers like the He-111, Do-17, and Ju-88 to fighter concepts that would showcase the challenges of their designs like the Bf-110 and the Defiant. History treats each of these aircraft differently, from the harsh evaluations of the heavy fighter concepts to what can only be described as the legendary and mythical position of the Spitfire. Each of these aircraft would have their own stories, from their design and development to their performance in action, and so it is important to give an introduction to what will be some of the primary characters of the future episodes of the series.

Before we dive too much into technical discussion, it is worth discussing a little of front about the tactics that were used among the fighter squadrons of both the Luftwaffe and the Royal Air Force. These tactics and formations are important because they would provide the structure to at least the early fighting during the summer of 1940. Both air forces have formed their aerial tactics based on the type of war they planned to fight, and their beliefs about how air combat should be approached and structured. Starting on the German side, the Luftwaffe built its fighter formations out of pairs of aircraft. Two pairs of aircraft made up a Schwarm, and the four aircraft of the Schwarm kept roughly 275 meters between each aircraft, that was always a rough number, nobody was out there will laser distance sensors of anything. The reason for this spacing was that 275 meters was right around the turning radius of the Bf-109 when at high speed, which meant that there was theoretically very low chances for any kind of collision. There was also some altitude differences between the different aircraft, again just to provide better spacing. Three Schwarm would then make up a Staffel, for a total of 12 aircraft. All of the aircraft in the Staffel would retain their same spacing, which would result in the total formation of the Staffel covering over 2 kilometers in the sky. This was important because at this point in history fighters did not have radar, and so it was completely up to simply their eyes to find enemy aircraft. Even the British pilots who were flying based off of information received from the radar stations on the coast still had to find the German aircraft, and the German pilots had far less information about the British aircraft that they would face while over Britain. The loose German formation allowed all of the pilots to be involved in these visual inspections, while also taking the time to follow each pilots respective leader, all the way up to the leader of the Staffel. When enemy aircraft were found, the general idea for the Germans was that the lead aircraft would be the ones going for the kills, while their following aircraft, or their wingmen, were responsible for protection and defense from enemy aircraft. This is one of the reasons that some of Germany’s top aces would build up very high kill totals, because kills were funneled into them by how the Luftwaffe structured its aerial tactics. But was also hoped that it would provide better protection for the best German pilots, because the most important predictor of success in aerial combat was experience.

Before the war the RAF took a different path for how to organize its fighters while they were in the air, primarily due to the fact that they believed they had a different mission than the Germans. The belief among the leaders of Fighter Command was that their primary purpose would be to attack formations of enemy bombers, which was completely different than facing enemy fighters, it brought with it different requirements and constraints which meant that the way to approach the combat was different. When attacking enemy bombers, British fighters could be assured that they would have the speed, maneuverability, and firepower advantage, and it gave the fighters freedom for how to approach any specific engagement. This resulted in an emphasis on set piece attacks on bomber formations known as the Fighting Area Attacks. These scripted attacking formations and behaviors would be designed to give the British attacking squadrons a known plan for as many scenarios as possible. For example if RAF fighters came upon a single enemy bomber, they were to arrange themselves in a line and each attack in succession from behind the bomber until it was shot down. Or if they were able to approach a formation of bombers from behind, they should all try and stay behind the formation, shooting until they exhausted their ammunition, hopefully destroying several bombers in the process. These types of variations continue on in many different ways to try and provide a toolbox for how to deal with any situation, I don’t think audio is a great way to describe them so we will not go too much deeper here. The important part though, is that this is how Fighter Command believed most of its fighters would be fighting the war, pursuing and attacking enemy bombers that were not being escorted by fighters. The Hurricane squadrons in particular were focused on these types of attacks and would spend the majority of their training time on mastering the various formations and actions described in the Fighting Area Attack guidelines. They also planned to use what was referred at as the vic formation. This formation involved three aircraft being in very close proximity, with the section leader being in front and then the other two aircraft following behind to the left and right, with one above and one below. If you have ever been to an airshow, or seen a picture of three aircraft together, they were probably flying in a vic formation, as it is perfect for getting really good photographs. It would prove to be far less good at being a combat formation. The challenge with the vic formation is that the three aircraft were very close together, and this greatly increased the chances of an aerial collision. The following aircraft therefore spent most of their time just trying to keep in position with the lead aircraft, instead of observing the skies around them. Along with some of the challenges involved with just trying to find the enemy due to having only 1 in 3 of the pilots actually focused on looking for enemy planes, the 3 fighter section also created numerical problems for the British fighters. In each 3 plane section only the section leader was supposed to attack enemy aircraft, with the other two aircraft in the section designated to defend and protect the section leader. This meant that only 1/3 of the British fighters would be actively engaging the enemy, compared to 1/2 of the German fighters in their 2 plane sections. The challenges in this setup would become apparent when fighter squadrons met, with smaller German squadrons having an equal number of designated shooter aircraft. In both the formation attacks and the vic formation combat experience would prove that there were challenges involved in actually putting them into place, but the reasons for why they were constructed do at least make some sense. During the late 1930s the RAF was expanding very rapidly, and there was a major concern that pilots would not have the training and experience to be able to have freedom in the skies. The concern is that the inexperienced pilots would not know what to do, or they would make critical mistakes that would cost aircraft and the lives of the pilots. Stricter formations and scripted actions were seen as a counter against this. The goal was to limit the mistakes that inexperienced pilots could make by reducing the number of choices they had to make while flying. In theory this was not a bad idea, but they perhaps dialed things in a bit too much. This is perhaps best exemplified by what the Germans called the British vic formations ‘Idiotenreihen’ or ‘rows of idiots’. There was some recognition among RAF leadership, including Hugh Dowding the head of RAF Fighter Command, that the tactics that were being taught were lagging behind the times. However, due to the rising fear of war, and the growing number of pilots that were entering into the RAF Dowding and other felt that it was too late to rewrite the tactics used, and that doing so would simply cause more confusion. In this evaluation they were probably underestimating how flexible the pilots were and how quickly they would adapt to new systems and new challenges. For example, due to experience over France some of the sections began to introduce small changes, like increasing the spacing between aircraft to make it easier to maneuver. Later alterations would also come into play, with one example of this adaptation being the introduction of a formation in which three sections flying in vic formation were followed by another that would fly behind them and weave back and forth to make it more difficult for German aircraft to attack from behind. There were also changes to how the British Fighter squadrons attacked German bomber formations, with a greater emphasis on head on attacks against bomber groups, with the higher closing speed making it more difficult for the bombers to react. The additional two benefits in this kind of attack was that it resulted in more danger for the bomber formation leader, who was often in charge of navigation and dropping the bombs, and it often resulted in the bombers breaking formation because well, they had an airplane flying at them at hundreds of miles per hour. Attacks from the rear of German bomber groups was still the most common, if only because it was safer due to the fact that the German bombers had fewer guns pointing that direction. There were limits to how quickly the RAF pilots could evolve their tactics though, especially during the height of the fighting in the late summer of 1940. This was due to the simple fact that they were spending all of their energy and time flying, with multiple sorties per day being the norm for many of the squadrons stationed in southeast England. They also had to contend with the fact that replacement pilots, often fresh from their abbreviated flight training, only had a limited amount of experience and ability, and so tactics could not stray too far from what they had been taught.

The bombers that would feature so heavily in the fighting during the Battle of Britain were the German triumvirate of the He-111, Do-17, and Ju-88. They would be joined by the Stuka in some scenarios, although its tour of duty over England was limited due to its range and its vulnerability to British fighters. The three German medium bombers were solid bombing platforms, and they would all be the real workhorses of the Luftwaffe during this period of the war. Each of them were equipped with machine guns for defense, two of them featured armored plating, and they all had self-sealing fuel tanks, an important innovation that reduced the probability of the aircraft bursting into flames, which was of course not desirable. They would also prove to be more difficult to destroy than the British expected. Before the war British fighter development had focused on placing as many machine guns as possible on the fighters, with 8 machine guns being landed on as the ideal number, with each of these guns being a .303 caliber. The problem with this armament is that it did not provide very much hitting power, especially against some of the more heavily armored German aircraft like the Ju-88. Most of the people listening to this podcast have probably seen pictures of Allied heavy bombers coming back from raids over Germany with tons of damage and bullet holes, and the same thing was happening to German bombers during the Battle of Britain. It was not uncommon for German bombers to arrive back at their airfields with 100 bullet holes, a testament both to their durability but also to the fact that the British were probably not arming their fighters with what they needed if they wanted to down German bombers. Fighter Command was not blind to this problem, and experiments had already happened where some of the machine guns were replaced by a 20mm cannon, which gave the British fighters a lot more firepower. However, there were challenges with keeping the cannons firing, and in fact 19 Squadron, one of the first to be given cannon armed fighters, swapped with a training unit because they got tired of their cannons jamming while in flight. While the German bombers would prove to be more durable than the British expected, they had their own challenges to deal with. One of them was simply how to hit a target, a problem that would be a major problem for all of the bombing forces during the war. Due to the proliferation of anti-aircraft guns bombers flew higher and faster over contested airspace, like the skies over Britain, and this drastically reduced their ability to actually hit anything. It was estimated that at 4,000 meters of altitude just 2 percent of the bombs dropped by an He-111 fell within 200 meters of the target, not exactly precision bombing.

The other problem for the German bombers was the fact that they could not always be escorted by German fighters all the way to their destination due to the limited range of the Bf-109. But this was a problem that the Germans had thought of before the war, and to try and fix the issue they built the Bf-110. The Bf-110 was the pinnacle of the pre-war heavy fighter concept, which was based on the idea that you could make a fighter with two engines which would allow for more speed and a much greater range. Then those two engine heavy fighters could be used to escort bomber formations deep into enemy territory where single engine fighters did not have the range. The Luftwaffe was not the only air force to request aircraft that met these heavy fighter requirements, for example the British would also have a heavy fighter with the Blenheim 1F that was based on the same concept. In theory the idea was good, bombers were safer with escorts and the only way to get the range required was with a larger aircraft. But then the actual fighting started. While range was a fundamental benefit of the twin engine fighter design, the trade off was in maneuverability. It was a larger, heavier aircraft and therefore could be out-turned by single engine fighters like the Spitfire and Hurricane. This was particularly noticeable anytime the Bf-110s needed to roll with their large Engine supporting wings creating a lot of resistance. There was basically nothing that a Bf-110 pilot could do to prevent an enemy fighter from getting behind them, which was not completely unexpected and was the reason that there was a machine gun mounted in the tail. But unfortunately for the pilots, it was found that one machine gun was not enough to deter or prevent attacks from behind. The Bf-110 would be used less and less as an escort fighter throughout the course of the fighting over Britain, although it would become a more effective fighter-bomber particularly against naval targets. This was a major reversal from the role that was imagined for the Bf-110 before the war, when the hope was that half of all fighter squadrons would be equipped with the Bf-110. The only reason that this did not happen by the the summer of 1940 was due to the fact that engines could not be created fast enough, and obviously the heavy fighters required twice the number of engines of their single engine counterparts. And so many of the squadrons that would have been equipped with the Bf-110 were instead given the Bf-109.

The Bf-109 was the most famous and most produced German fighter of the Second World War, and in 1940 it can be claimed that it was the best fighter in the air. Just like other fighters during the Battle of Britain it was a mid-1930s design that had been improved in the intervening years, especially after it received its first combat experience in Spain. After the invasion of Poland the Bf-109 had ruled the skies over Europe, with massive kill counts that were mostly due to it being simply better than other aircraft. And in some ways that technical advantage would be maintained over Britain. During the summer of 1940 there were three key design differences between the Bf-109 and the British fighters that fuel injection, a variable pitch propeller, and heavier armament. The fuel injection situation was interesting, and would be one of the more interesting design differences between the British and German fighters. The Bf-109s engine, the DB 601, was fuel injected and that meant that fuel was forcefully injected into the engine cylinders while the engine was running. The Spitfire and Hurricane instead used a float carburettor system which was a simpler technology but had one very important downside. In a situation in which the aircraft was experience negative vertical g-forces, like at the beginning of the dive, the engine would cut out. This was not a fatal flaw for the British fighters, and the engine would restart as soon as the g-forces changed, but in the moments where their engine did not work the Bf-109 could often escape or move into a better position. The Bf-109, with its fuel injection, had none of these problems. The second major advantage that the Bf-109 had was the fact that they used an electric controlled variable pitch propeller. This provided major performance benefits, particularly as the altitude at which fighting was occurring continued to climb during the early war years. A variable pitch propeller simple means that the angle on the propellers can change when required, so there would be one setting for take off when maximum thrust was required, and then another for leisurely flight, another for high altitude high performance, etc. This provided a more consistent performance profile at all altitudes, and it would be something that the British would quickly move to integrate into their own fighters. Both of these advantages, the fuel injection and the propeller, allowed the Bf-109 to get into position, at which point the heavier armament of the aircraft came into play. The British fighters famously had 8 machine guns, four in each wing, while the 109 had one machine gun in each wing and then also a 20mm cannon in each wing. While the cannons were heavier, the machine guns could be provided with about three times more rounds than the British machine guns had access to, which gave them a much longer total firing time with one combat load. With a much smaller number of machine guns, and the fact that the German guns fired slower, the theoretical maximum damage per second was much smaller, but that only mattered if you hit something, and the German pilot would have more opportunities to hit something. Also, the real damage potential of the 109 came from the cannons, which had only 60 rounds each, which gave the pilot only 7 seconds of firing time for the cannons, however, even a single hit with one of the cannon rounds could destroy a British aircraft, it was a real trade of volume for hitting power, which would serve the Germans well at this stage of the war. While the 109 was a really good fighter, it was also piloted by some of Germany’s best. Some of the German fighter pilots had years of combat experience under their belt by the summer of 1940, and incredibly successful experience at that, and that experience would be critical to getting the most out of the 109. There were many quirks of the aircraft that experienced pilots could take advantage of in combat, for example the 109 had a relatively high stall speed, but it has good stall stability so that the pilot did not lose control. This meant that it was possible to do a purposeful stall which would cause a rapid loss in altitude, which could be a good thing. It could also be a disastrous mistake, because it involved losing a lot of speed very quickly. A good pilot could gain an advantage, another would just get himself killed.

On the opposite end of the spectrum when it came to being able to do cool, but dangerous things, was the Hawker Hurricane. The Hurricane would be the most numerous British fighter during the Battle of Britain, equipping about 2/3 of all Fighter Command squadrons when the fighting started. It was a workhorse, but not exactly a thoroughbred, that did not mean that it was useless though. Sure the Hurricane was slower than the 109, its armament was not as powerful, but in the right circumstances it could get the job done. And the good news for the RAF and the Hurricane pilots is that there were many German targets over Britain that were not 109s, specifically German bombers. This is why, whenever possible Hurricane squadrons attempted to engage enemy bomber formations while the German fighters were left to the Spitfires. This was not always possible though, and when it was not possible, the key for the Hurricanes were to bring the fighting down to lower altitudes. Due to different performance profiles as the altitude got higher the 109 gained a greater and greater advantage over the Hurricane, but below 20,000 feet these differences were reduced. This was mostly thanks to the fact that the Hurricane could turn much quicker than the 109, which often meant that there were opportunities for the Hurricane at those lower altitude. Now, of course, because of its slower speed, there was nothing that the Hurricane could do to prevent the German fighter from just running away, but that was not their goal, their goal was to protect the bombers and destroy British fighters, and so if the Hurricane could just stay alive and distract the 109s that was at least some small victory. Over the course of the battle the Hurricane would claim more aerial victories than the Spitfire, mostly due to the combined impact of having bombers as their primary target and the fact that there were just so many more Hurricanes. And since 1940 there have been many conversations about which British fighter was more important to the British victory, the higher performance Spitfire or the more numerous Hurricane. I think that the Hurricane was the most important of the two fighters, but it has nothing to do with performance or aerial victories. One of the benefits of the Hurricane was that it was a simple design, easy and quick to build, and this allowed it to enter service quicker than the Spitfire during the 1930s and allowed production to be ramped up at a higher rate. The British did not need perfect fighters in 1940, they needed capable fighters, and the Hurricane was that capable fighter. It was more important to victory because it was boring, almost outdated, mundane, but there were a lot of them and as much as people like to talk about the importance of technology, numbers are still important, and numbers are what the Hurricanes provided.

While the Hurricane was an important part of Fighter Command, nobody should be under any illusion that the Spitfire was not the belle of the ball. I struggle to think of another example of an event during the war that will forever be as strongly connected to a single item as the Battle of Britain and the Spitfire. The roots of the Spitfire were in a 1935 air ministry specification named F10/35, which called for a fighter that could reach a speed of at least 310 mph while carrying at least 6 machine guns. This was the same specification that had resulted in the Hurricane, but Hawker’s fighter would enter into large production much quicker thanks to its simpler design and technology. The production of the Spitfire was far slower, and the first production Spitfire would not be delivered until May 1938. This put it well behind the original production schedule, and it would not seriously catch up to those expectations until the war years. But it was not for lack of trying, Supermarine outsourced most of its production quite early on because it could not keep up with production, and then the shadow factories scheme provided greater production capacity, but still not enough. By the start of the war there were only a few hundred in active service, a number that was originally scheduled to be reached years earlier. But production was ramping up in speed, just in time for the Spitfire to participate in its most famous action. In some ways it was better than the 109, in some ways it was worse, and when these strengths and weaknesses were combined on both sides it could be difficult to predict the outcome of a dogfight.

Both the Hurricane and Spitfire were very successful aircraft during the war, but that was not true for all of the participants in the Battle of Britain. Before the war there were many competing theories of how best to participate in an air war, and these disagreements had huge impact on how air forces were built. The discussions around strategic bombing were an important large scale example of this, completely shifting air strategy and doctrine. However, there were countless other ideas that would result in certain aircraft being produced in the 1930s that would not prove to be very useful when the war started. The heavy fighter concepts that we discussed earlier for the Bf-110 was an example of this, they were aircraft that were designed for a understandable reason but which did not end up really working out due to the advances made by other aircraft types. But then there were other aircraft where the entire concept of their design and their intended purpose would prove invalid once the war started. There are a few different examples you could pull from here, but in this episode I am going to highlight the Boulton Paul Defiant. The Defiant is a case where expectations and reality could not have been more different, because before the start of the war there were conversations about the Defiant being the fighter of the future. And this was because instead of having forward firing machine guns fixed in its wings, like the Hurricane or Spitfire, it had 4 machine guns mounted in a manned electrically powered turret behind the pilot. This allowed it to fire above, behind and to the sides, but importantly the aircraft did not have any guns firing forward. The theory was that this would make it easier to attack bombers, since it would be able to track and fire on targets for a longer period of time and from many different angles. The Defiant had its supporters before the war, with Churchill in particular being convinced that the Defiant concept was simply superior to fixed gun fighters. But there were problems, serious problems, for the Defiant if it ever ran into enemy fighters. The biggest problem was the firing arcs and speed of traverse for the turret. The guns could not fire below the horizontal, and while this made them great for engaging bombers from below, there was nothing they could do to protect from an enemy attack from below. It was then often difficult to get the plane in the right position for the guns to be of any use against enemy fighters, and the positioning and maneuvering requirements were much less intuitive than for a forward firing fighter. It did not help that, because there were two people in the aircraft, they had to communicate, with the pilot and the gunner having to coordinate their actions to bring targets into the sights of the guns. This was a challenge against slower bombers, but almost impossible against fighters who would be moving around the Defiant as fast, if not faster, than the turret could traverse which meant it needed assistance from the pilot. These problems would never be solved, and the best that could often be done would be for the Defiants to line up and execute a descending spiral formation so that the guns of one could cover another if they were attacked by fighters. Eventually the Defiant would be withdrawn from daytime fighter service during the Battle of Britain and shifted to a night fighting role, a role it would maintain until the introduction of more dedicated aircraft in 1942.

Along with the aircraft models and designs, there were a whole host of other possible topics for discussion that would have a major impact on the overall course of the air war. Engine design, pilot training, machine gun and cannon development, survivability and safety, even small things like cockpit design. But one of those items that I will highlight, is high octane fuel. The quality of the fuel used at any given time during the war is not frequently discussed, and instead all conversation about fuel focuses on quantity. This is for good reason, it doesn’t matter what the quality of the fuel is if it does not exist. But when it came time to put fuel in particularly fighter aircraft the octane value of the fuel does have an important impact on performance. The octane number, which is often displayed on fuel pumps at civilian fuel stations, is a rating of how high the pressure and the temperature can be on the fuel before it prematurely detonates in the engine. The goal is to avoid that premature detonation because it impacts the efficiency of the engine, but you also want as much pressure as possible in the engine because that increases engine power output. The British would have access to 100 octane fuel, provided by American firms and shipped over to Britain, while the Germans would have to work with the 87 octane fuel that they had access to, which is very similar to the most common fuel found at fueling stations today. High octane fuel could provide more power, but only before around 18,500 feet in altitude, because any higher and the air was not thick enough to push enough into the engine to make use of the higher octane. But those first 18,500 feet were important because more power at that level gave the British fighters a faster rate of climb off of their airfields. The exact impact that this would have on climb rate was not always exactly the same, but it would save somewhere around 40 seconds for the initial climb of a Spitfire, allowing it to reach 20,000 feet in 7 minutes instead of over 7 and a half. This was not always important, but when it was it was very important. Having access to high octane fuel did not change the outcome of the Battle of Britain, but it is an interesting example of how deep the rabbit hole can go when looking at how each side prepared for the fighting and the differences that can be found that may not have swung the battle either way but which might have nudged specific events one way or another. Next episode will zoom out a bit, from the intricacies of fuel supply and instead focus on the pilots that would fly for the RAF Fighter Command during the Battle of Britain and the man who would give them their collective name The Few, in one of his famous speeches, Winston Churchill, I’m guessing you have heard of him.