The Bf 109

Germany’s “knife” in the air

A Bf 109G-6 in flight
(Photo: Bundesarchiv)

The German Bf 109, also known as “the Messerschmitt,” stands shoulder-to-shoulder with the P-51 Mustang and the Supermarine Spitfire (Read our earlier article) as some of the most iconic fighter planes of World War II. The most advanced warplane when it entered service, the Bf 109 became the second most highly produced warplane ever, as well as the plane with the most kills in World War II. It stayed in production throughout the war and was eventually brought low not by its deficiencies but by the total collapse of the German war economy.

First of all, a few words about the plane’s designation are in order. Every aircraft design in the Third Reich (military or civilian) was assigned a two-letter identifier based on its manufacturer, and a (theoretically) unique three-digit number. The manufacture ID was always an abbreviation of the company’s name: “He,” for example, stood for Heinkel, or “Fw” for Focke-Wulf. “Bf” was assigned to the Bayerische Flugzeugwerke, the “Bavarian Aircraft Works,” which designed and began production of the Bf 109 in the mid-30s. The company’s chief designer, Willy Messerschmitt, became the chairman and managing director in 1938, and the corporation was renamed to Messerschmitt AG. Further designs from the company were designated as “Me,” but the Bf 109 was already in service so the old letter combination stuck for official purposes – at least in theory. Even German Air Ministry documents often used “Bf 109” and “Me 109” interchangeably, and both the Allies and some German pilots called the plane “the Messerschmitt.” Willy Messerschmitt’s family name literally meant “knifemaker,” and “Messer,” “knife,” became a common nickname for the company’s most iconic plane. This practice even carried over into at least one other language: a post-version of the plane, used by the Israeli Air Force as its backbone fighter in its early years, was officially named “sakeen,” meaning “knife” in Hebrew.

Messerschmitt (right) with Minister of Armaments and War Production Albert Speer (left) and State Secretary of the German Air Ministry Erhard Milch
(Photo: Bundesarchiv)

But back to the history of the Bf 109. The Versailles Treaty at the end of World War I forbade Germany to maintain an air force and develop new military aircraft. Hitler violated this stipulation by having pilots trained in secret, with the existence of the new German air force, the Luftwaffe, made public in early 1935. In 1933, in preparation of the grand reveal, the Air Ministry created broad outlines for four types of aircraft: a single-seat fighter, a two-seat heavy fighter, a tactical bomber and a multi-seat medium bomber. The first of these was supposed to serve as a short-range interceptor, replacing the obsolete biplanes Germany had in that role at the time.

The third prototype of the Bf 109
(Photo: Ad Meskens / Wikipedia)

Four designs were submitted, one by the Bayerische Flugzeugwerke, with the prototypes arriving for testing in February 1936. Messerschmitt’s design incorporated a “lightweight construction” philosophy that he already demonstrated on the Bf 108, a sport and touring plane. His submission had an all-metal monocoque skin (meaning that loads are supported by the external skin rather than an internal frame), a closed canopy, retractable landing gears, cantilevered wings (without external struts of supports) and a high wing load (meaning relatively small wings for the plane’s mass). Another feature typical of Messerschmitt’s designs was minimizing the number of separate construction parts. For example, a single pair of complex-shaped brackets functioned as both the lower engine mounts and the landing gear pivot points. Another design consideration was that the plane was going to be stationed at forward airbases that would not have extensive maintenance and repair facilities. Many parts of the plane were covered by large panels that gave easy access to the internal components, while pipe connections were color coded and mounted in the same spot wherever possible. As a result of this maintenance-oriented design, the powerplant could be replaced much more quickly. This solution also inspired the later German Kraftei (“power-egg”) design, in standardized attachment ports allowed the engine and its ancillary equipment to be rapidly replaced with little disassembly.

A Bf 109 getting its engine replaced
(Photo: ww2aircraft.net)

The test pilots, who were used to flying biplanes, were initially skeptical of the design, but it quickly proved the clear winner thanks to its power, speed, and having fewer problems than its competitors. This is not to say it didn’t have problems. One issue that was noticed early was that the plane’s nose was pointing upward at a relatively steep angle while on the ground, so the taxiing pilot couldn’t see the ground in front of him. Additionally, the front wheel struts were attached to the fuselage rather than the wings, which was the common design at the time. On the upside, this meant that the wing didn’t need to bear the plane’s weight on the ground, and that it could be removed for servicing while leaving the landing gear in place. The tradeoff was that the two wheels were very close to each other: if one ran into a ditch, the plane was very likely to tip over to the side. A partial solution was provided by splaying the wheel struts slightly outward to increase the distance between them, but this, in turn, meant that the loads during takeoff and landing were transferred up the struts at an angle.

A BF 109R with its wings removed at the RAF Museum. You can see how the wheel struts connect to the fuselage rather than the wing, how they’re very close to each other, and how the pilot wouldn’t be able to see the ground in front of him.
(Photo: Alan Wilson / Wikipedia)

Pilots had to taxi in a sinuous fashion so they could see the ground, but the turns placed even more stress on the wheel struts. Additionally, the rudder was too small to counteract the swinging motion created by the propeller’s wing during takeoff. All of these shortcomings added up to a surprising amount of accidents: five (some sources claim ten) percent of all Bf 109s was lost during takeoff or landing accidents.

The Bf 109 also had outstandingly positive features compared to its contemporaries. Liquid-cooled engines were vulnerable to hits to the cooling system. The Bf 109 had two cooling radiators, and models from F onwards had a cut-off system between them. If one radiator was hit, the pilot could still fly with the other functioning, or he could shut down both and still have five minutes of airtime for an emergency landing.

Since the wings were thin, they could not easily accommodate guns. The original plan called for either two machine guns mounted in the engine cowling, equipped synchronizing gears so they only fired when the propeller blades were not directly in front of them; or a single heavier caliber (20 or 30 mm) autocannon which was placed behind the engine and fired between its cylinder banks, with the bullet coming out of a hole in the middle of the propeller. This design, called the Motorkanone (“motor cannon”) not only allowed the placement of a gun deep inside the plane where it couldn’t go otherwise, but also reduced the weapon’s recoil thanks to the engine’s mass.

A first lieutenant checking the accurate alignment of the gun firing through the engine and the propeller
(Photo: Bundesarchiv)

The armament didn’t stay for long. In 1937, it was designed that the Royal Air Force’s Hawker Hurricane and the new Supermarine Spitfire had eight guns, forcing a redesign of the Bf 109 to keep up with its intended adversaries. As mentioned before, the wings were not designed to hold weapons inside them, and there was barely enough space for a single machine gun or 20 mm autocannon per wing – and even these had to be fed by a complicated belt system. The wing-mounted guns were removed from the F model onward and replaced by a pair of 20 mm autocannons in external gondolas (pods) slung under the wings. These, along with the Motorkanone, gave the plane pretty heavy firepower against Allied bombers, but the external pods were heavy (474 lbs / 215 kg per gondola with ammunition), making the plane a worse dogfighter.

A Bf 109 G-6 with one underwing cannon gondola visible
(Photo: Bundesarchiv)

The Bf 109 became the Luftwaffe’s primary fighter plane, with over 34,000 built – the only warplane ever built in larger numbers was the Soviet Il-2 Shturmovik. While originally designed as an interceptor, its many models and variants eventually covered a wide range of profiles: bomber destroyer, bomber escort (not very successfully), reconnaissance plane, night fighter, long-range fighter (with external fuel tank), ground attack craft and fighter-bomber.

The Bf 109 could be built in such numbers partially thanks to slave labor. Several aircraft parts were built at the Flossenbürg concentration camps, and later at other camps as well, under the oversight of Messerschmitt engineers. This became even more prevalent after August 1943, when the Allies bombed Messerschmitt’s Regensburg factory. By mid-1944, one-third of Regensburg’s production was actually built in concentration camps and only the final assembly was performed at the factory.

Bf 109G-6s under assembly at a factory
(Photo: Bundesarchiv)

The Bf 109 made its public debut at the 1936 Berlin Olympics (Read our earlier article), but its first true successes came the following year, at a 1937 air show in Switzerland. The plane won in three events: the 125-mile (202 km) speed race, the Alpine round flight, and the patrol flight.

Models A to D saw service before World War II, and first fought in the Condor Legion, a German unit sent to aid General Franco’s Nationalist forces in the Spanish Civil War, where it made easy work of the obsolete Soviet planes flown by the Republican side.

A Bf 109A serving with the Condor Legion during the Spanish Civil War
(Photo: unknown photographer)

The E or “Emil” model went into production in 1938 and was the version the Luftwaffe began World War II with. The model was superior to anything it flew against over Poland, Denmark, Norway, the Netherlands and France. It first encountered serious opposition over Britain in the air campaign designed to break the Royal Air Force before Operation Seelöwe, the planned German invasion of the United Kingdom. The Bf 109E was generally well-matched against the contemporary marks of the Spitfire – the British plane was slightly faster and had a tighter turning radius which it could exploit in a dogfight, but the Bf 109 operated better at high altitudes.

A Bf 109E
(Photo: Royal Air Force, Netherlands)

The T model (“Träger”, meaning “carrier”) was designed with carrier-based operations in mind. Germany only completed a single carrier, the Graf Zeppelin, and that never saw combat, so the idea proved rather useless. A small number of these planes was stationed in Norway at airfields with short runways and strong crosswinds.

A tropicalized Bf 109E-4 in North Africa
(Photo: Bundesarchiv)

Eventually, it wasn’t the Bf 109 itself that cost Germany the battle, but the way it was used. It was a short-range interceptor, and could only stay above Britain for about 10 minutes before having to head for home. This was sufficient in the first stage of the campaign, when the planes swept ahead of German bomber formations to take out British interceptors, while the bombers themselves were escorted by long-range two-engine Bf 110s. The 110s, however, proved inadequate to the task, so the Bf 109 was pressed into service as bomber escort. It proved abysmal at the new job, since it had to turn around and abandon its charges before those could reach their targets.

A Bf 109E-1 that crashed during the Battle of Britain
(Photo: Imperial War Museums)

The F model (“Friedrich”), developed in 1939-40, was an overall improvement over the various versions of the Emil, and racked up a staggering victory count during Operation Barbarossa, where it came up against large numbers of obsolete or sometimes just tactically inflexible Soviet planes. 105 German pilots were credited with 100 or more kills during the war, racking up a staggering 15,000 kills between them – and a large part of that was the Bf 109 running rampant over Russia. The model also flew in North Africa, but needed “tropicalization” kits to make it work in the hot, dry, sandy environment.

A Bf 109F-4 captured by Britian. It was given RAF colors and rondel, but retained the white “11” and the bomb icon of its old German unit.
(Photo: Imperial War Museums)

The G model (“Gustav”) was introduced in 1942, and became the definitive version, with roughly half of all Bf 109s produced being this model. Some specimens came with a pressurized cockpit and a nitrous oxide injection system for better high-altitude performance. The proliferation of numerous specialized versions within a single model became even more prevalent with the Gustav than earlier models, with versions ranging from G-1 to G-14, several of them with additional subtypes. To make things even more complicated, various field modification kits were also introduced. The various Rüststand kits could adapt a plane to a specific mission profile, such as long-range fighter bomber; Umrüst-Bausätze kits enabled smaller modifications that didn’t change the plane’s designation.

A Bf 109G-10 at the National Museum of the United States Air Force
(Photo: U.S. Air Force)

The K model (“Kurfurst”) was the last to see mass production. Germany’s economy was under tremendous strain in the late years of the war once the tide turned in Africa, the Eastern Front and the Western Front alike. The bewildering array of different models, series, modification kits and factory conversion in existence made the production and maintenance of the Bf 109 a logistical nightmare the country could no longer support. The K model was an attempt to do away with the chaos and standardize the plane. Designed in 1943 and going into production in mid-1944, the plane was, by all accounts, a match for Allied fighters in service at the time, but it was brought low by the lack of well-trained, let alone experienced pilots. The Luftwaffe’s pilot corps was reduced to barely trained men pressed into service prematurely, who could not use the otherwise competent plane to its full potential.

Bf 109K-4 planes
(Photo: airpages.ru)

A few more obscure versions of the Bf 109 existed on paper or as prototypes that never saw production. The X model was a planned export version using an American engine instead of the German DB 601, but the war naturally put an end to any prospect of that. The Z (“Zwillings”) model was two Bf 109s connected side by side as a tandem plane. Two fuselages and two engines would have meant much longer range and the capacity to carry much heavier armament, such as five 30 mm cannons. A single plane was built and subsequently damaged in an Allied air raid. Interestingly, the North American F-82 Twin Mustang, the last piston-engine fighter in the U.S. Air Force, did essentially the same thing with two P-51 Mustangs.

The North American Twin Mustang, a plane similar to what the Bf 109Z would have been
(Photo: U.S. Air Force)

The Bf 109TL was supposed to be a jet version of the plane, to be produced if the Me 262 project (Read our earlier article) didn’t pan out. It took the fuselage of a Bf 109H (the high-altitude model) with some new parts, the wings of another experimental high-altitude interceptor, the undercarriage from yet another prototype fighter, and the same jet engines that were used on the Me 262. On paper, the plane’s performance looked possibly even better than the Me 262’s, but the plan was abandoned due to the many modifications that would have been necessary.

An Avia S-199 (a postwar version of the Bf 109) of the Israeli Air Force
(Photo: unknown photographer)

The Bf 109 was one of the staple fighters of the war. Beside Germany, it was also flown in smaller numbers by most Axis nations, and even some of their enemies (Czechoslovakia and Greece) who managed to capture a few. It was also flown by Finland in their war against the Soviet Union, and as mentioned before, even by the nascent Israeli Air Force after World War II. A few more were captured by the United States, Britain, the Soviet Union and France and used for testing. You can see surviving examples on some of our tours, such as the Britain at War Tour or the Third Reich Tour.