v2.0.0 / 1 of 3 / 01 mar 02 / greg goebel / public domain
* The Bf-109 incorporated the latest aeronautical technologies when it was introduced in the mid-1930s, but due to official resistance there was still an element of luck in its adoption by the German Luftwaffe. However, even the initial variants of the Bf-109 proved impressive, and the type quickly matured to the excellent Bf-109E, which gave Hitler's Reich a great advantage in the opening rounds of World War II. This chapter describes the origins of the Bf-109 and its evolution up to the Bf-109E.
* The path that led Willy Messerschmitt to the Bf-109 was a complicated one. Born in 1898, Messerschmitt formed his own company in March 1926, named the "Messerschmitt Flugzeugbau GMBH", with financial help from the Bavarian state government.
However, the state government also had an interest in another aircraft firm named "Bayerische Flugzeugwerke (BFW or Bavarian Aircraft Company)". Unable to support both firms, the state government persuaded them to merge in September 1927, with Messerschmitt providing design and development expertise while BFW handled manufacturing. The company was established in Augsburg, Bavaria.
The first aircraft to be built by the new firm was an all-metal single-engine monoplane transport that could carry 8 passengers, named the "M-20". The aircraft appeared very impressive, and the German state airline, Deutsche Lufthansa (DLH), ordered two. However, the M-20's development suffered delays, and when the prototype crashed during trials in February 1928, killing its pilot, the director of procurement of DLH, Erhard Milch, cancelled the order.
BFW built a second prototype in a hurry and put it through successful flight tests. The order was hesitantly reinstated, with Lufthansa requesting a ten M-20s. Unfortunately, there were further crashes. The DLH cancelled the order again, demanding repayment of advance funds.
Germany was in the grips of the Depression at the time, and BFW went bankrupt in June 1931. Fortunately, BFW's board of directors were adept businessmen, and by 1933 BFW was back in operation again. However, the whole fiasco had led to bitter feuding between Messerschmitt and Milch. As Milch had given the post of Secretary of State for Aviation when Adolf Hitler came to power in 1932, prospects for contracts for BFW from the new Nazi government appeared slim.
To stay in business, Messerschmitt looked for work outside of Germany and landed two contracts from Romania, including one for the "M-36" commercial transport, and one for the "M-37" trainer. Milch publicly denounced the transactions as treasonous, and Gestapo officers paid Messerschmitt and other BFW officials visits to investigate.
Messerschmitt held his ground and insisted that he had no choice, as the German government refused to do business with BFW. Nothing more came of the investigations, possibly because Theo Croniss, a high official of BFW, was a close friend of Minister of Aviation Hermann Goering, and in fact had been placed at BFW at Goering's request. It also appears that some German government officials were sympathetic to Messerschmitt's complaints about government indifference.
After a long streak of troubles, Messerschmitt and the BFW got a break in late 1933, when the German Air Ministry ("Reichs Luftsfahrt Ministerium" or "RLM") decided that Germany should show off its capabilities in aviation by racing in the 4th "Challenge de Tourisme Internationale", to be held in 1934. BFW and other German aircraft manufacturers were asked to develop air racers for the event.
In fact, BFW had built a racer for the 1932 Challenge de Tourisme Internationale, but their "M-29" was disqualified from the race after two of the four built crashed. Unintimidated by this bad luck, Messerschmitt decided to build a new air racer, based on the M-37 trainer he was designing for the Romanians.
The result was the "Bf-108A", which was first flown in February 1934. The Bf-108A was a two-seat low-wing monoplane with dual controls, a flush-riveted fuselage, retractable "tailsitter" landing gear with a tailskid, a Hirth HM-8V inverted-vee engine with 250 horsepower, and a three-blade propeller. It could fly at 320 KPH (200 MPH) and was extremely agile. Five more prototypes followed.
Then, on 27 July, just before the race, the initial prototype crashed, killing its pilot. Messerschmitt and his staff worked frantically to ensure that the remaining five Bf-108As were qualified without mishaps.
The Bf-108A came in third in the competition. This was a bit disappointing, but the Bf-108A was clearly an excellent aircraft, and in fact as pilots got their hands on production machines, they started setting records with it. German aviatrix Elly Beinhorn flew one named "Taifun (Typhoon)" from Berlin to Constantinople in one day, and the BFW adopted the name for the aircraft.
The popularity of the Bf-108A led Messerschmitt to improve the design into a four-seat touring aircraft designated the "Bf-108B" that could also be used for military liason and air ambulance roles. The Bf-108B featured an Argus As-8C inverted-vee piston engine with 240 horsepower in place of the Hirth engine, a tailwheel instead of a tailskid, and a two-blade fixed propeller.
The Bf-108B Taifun proved even more popular than the Bf-108A, and hundreds
were built.
MESSERSCHMITT BF-108B TAIFUN:
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spec metric english
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wingspan 10.51 meters 34 feet 6 inches
length 8.30 meters 27 feet 3 inches
height 2.3 meters 7 feet 7 inches
empty weight 880 kilograms 1,940 pounds
loaded weight 1,355 kilograms 2,990 pounds
max speed at altitude 300 KPH 186 MPH / 162 KT
service ceiling 6,000 meters 19,700 feet
range 1,000 kilometers 620 MI / 540 NMI
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Nord also built stock Bf-108Bs during the war, and after the war the French firm continued the production of the type, with the Bf-108B built as the Nord N.1000 "Pingouin (Penguin)" and the Me-208 as the "Nordalpha" and "Ramier (Woodpigeon)", with Renault 6Q or Potez 6 engines.
Interestingly, two Bf-108Bs used by the German embassy in Britain before the war were abandoned by the embassy staff on the outbreak of the conflict, and were impressed into British service as "hacks". They were called "Aldons" by their crews. The Bf-108B also served with the Luftwaffe as a liason aircraft.
* Messerschmitt and his colleagues were encouraged by the Bf-108, and decided they could compete in a competition for a new fighter for the Luftwaffe (German Air Force).
The RLM specification had been issued in early 1934, and dictated a fast monoplane, armed with at least two MG-17 7.9-millimeter machine guns, and capable of being fitted with the new liquid-cooled inverted vee-12 engines being developed by Junkers and Daimler-Benz.
The request had been sent to other German aircraft manufacturers, including Focke-Wulf, Arado, and Heinkel, but Milch had blocked it from being sent to BFW. Lobbying by Theo Croniss with his friend Hermann Goering; enthusiasm by a clique of Luftwaffe officers for the Bf-108A; and heavy demands on German aircraft production overcame Milch's dislike of Willy Messerschmitt, and in 1935 BFW was given a contract to participate in the fighter competition.
Milch let it be known that as far as he was concerned there would be no follow-on production contract granted to BFW under any circumstances. Messerschmitt had to decide between going ahead with the fighter or taking a professorship at Danzig Technical University. Messerschmitt, having faith in his design and knowing that Milch expected him to fail, decided to push on with the fighter.
The new aircraft, the "Bf-109A", had been in design in parallel with the development of the Bf-108, and it was ready to fly by August 1935. It was, like the Bf-108, a low wing, all metal, flush riveted monoplane with leading-edge slats and retractable "tailsitter" landing gear. It had a single-seat cockpit, with a fully enclosed canopy that swung open to the right. These innovations were not new in themselves, but the Bf-108 and Bf-109A were among the first aircraft to put them all together.
As the advanced German engines were not yet available, the first prototype used a British liquid-cooled Rolls-Royce Kestrel VI twelve-cylinder upright-vee engine with 695 horsepower for take-off. This engine was used in other competing fighter prototypes for the same reason.
The first prototype ("Versuchs 1" or "V1") was run through preliminary flight tests in September 1935, and then passed on to the Luftwaffe Test Center at Rechlin.
The test pilots were suspicious of the Messerschmitt design. It looked frail compared to the heavier aircraft they were used to; they were uncomfortable with the fully enclosed cockpit, which was cramped in any case; were unhappy with the aircraft's high wing loading; and didn't like the steep ground angle, which restricted their forward view on take-off. The head of the RLM procurement office, World War I ace General Ernst Udet, was openly contemptuous, saying: "That will never make a fighter!"
The concerns were completely justified in one respect. The main landing gear of the Bf-109A had a narrow track, hinged in the fuselage to retract into the wings. The narrow gear not only made the aircraft a "roller skate" on the runway but also tended to collapse. In fact, the prototype suffered a landing gear failure when it was handed over to the Luftwaffe for test. This problem would dog the Bf-109 all the rest of its days.
Whatever problems the Bf-109A had on the ground, it was agile and fast in the air, and fighter became one of the front-runners in the competition. Udet overcame his original suspicions and became an enthusiastic advocate of the type.
In the meantime, acting as if he already won the competition, Messerschmitt pressed on with the second and third prototypes. The "Bf-109-V2" was completed in October 1935. It was similar similar to the V1, but used a 610-horsepower Junkers "Jumo 210A" engine instead of the Kestrel, and had other minor differences, such as a small intake in the cowling to provide cooling for the two machine guns, which were to be mounted there to fire through the propeller arc.
The Bf-109-V2 was not actually fitted with guns. The third prototype, the "Bf-109-V3", was the first armed aircraft in the series, fitted with the required pair of MG-17 7.9 millimeter machine guns, with 500 rounds per gun (RPG). It was otherwise identical to the Bf-109-V2. Problems in obtaining the Jumo 210A engine delayed the first flight of the Bf-109-V3 until May 1936.
By this time, the Bf-109A was clearly becoming the front-runner in the competition. The Arado and Focke-Wulf entries had fallen to the side early on, due to poor performance and mechanical failures, and the Bf-109A was demonstrating itself superior to the Heinkel machine, the "He-112". German intelligence stacked the deck even more clearly in favor of the Bf-109A when they reported that the British were working on a conceptually similar advanced fighter, the Supermarine "Spitfire".
The RLM was sufficiently impressed by the Bf-109A to order ten preproduction aircraft, though they ordered ten He-112s as well. Willy Messerschmitt had won his gamble, and Milch could only fume that he had given Messerschmitt as many chances as he had.
* The initial Bf-109 preproduction aircraft, the "Bf-109-V4", was first flown in November 1936. It was much like the Bf-109-V3, being powered by a Jumo 210A engine, but incorporated a third MG-17 machine gun, situated between the engine cylinders and firing through the propeller hub. The engine-mounted weapon fitted in many Bf-109 variants is often referred to as a "Motorkanone", though it is unclear if this also applied to small-caliber guns as well as automatic cannon.
The improved armament was the consequence of reports that new British fighters had four guns instead of two. The question of armament would be another long-running issue for the Bf-109.
Two additional preproduction Bf-109s, designated "Bf-109-V5" and "Bf-109-V6" were flown in the next two months, featuring an improved "Jumo 210B" engine, as well as a number of other minor enhancements, such as a stronger forward windscreen and replacement of the gun cooling intake by three flush cooling slots.
In 1936, Nazi Germany had decided to assist Generalissimo Franco's Nationalist forces in the Spanish Civil War, and participation in a shooting war gave the Luftwaffe an opportunity to evaluate the Bf-109 in combat. The three preproduction aircraft available at the time were sent to Seville in December 1936 and January 1937, to be flown by the German "volunteer" group in Spain, the "Condor Legion".
The preproduction aircraft suffered from a number of teething problems in combat service, as would be expected for prototypes. Taking that into consideration, they otherwise gave the Luftwaffe good reason to be excited about the new fighter. The three prototypes were returned to Augsburg, but would be replaced in Spain by improved successors.
In the meantime, the RLM had placed orders for a first batch of 30 production aircraft, with the designation "Bf-109B". The first rolled off the production line in February 1937. They featured a "Jumo 210Da" engine, rated at 680 horsepower for take-off, driving a Schwarz two-blade fixed-pitch wooden propeller. The third machine gun that fired through the prop spinner was not fitted, as trials had shown it caused engine overheating problems.
The Bf-109Bs were transferred to the Condor Legion in Spain as soon as their pilots had been trained on the new aircraft, which was given the nickname "Bertha". In Spain, the German pilots fought with Soviet Polikarpov I-15s and I-16s. At low altitudes, the maneuverable Polikarpovs could outfight the Bf-109B, and so the Luftwaffe pilots quickly learned to take the fight to high altitudes where they had the advantage.
A Bertha was forced down behind Republican lines later in the civil war when it ran out of fuel, and the French discreetly asked to inspect the aircraft. The Republicans agreed to the request. A French team went to Spain and wrote up a detailed report that praised the aircraft, but the report was made secret to avoid a diplomatic squabble, and few ever read it.
* Following the first batch of 30 Bf-109Bs, in July 1937 the propeller was changed from the fixed two-blade wooden propeller to a variable-pitch two-blade metal propeller. The new propeller was an American Hamilton Standard design, built under license by the German firm VDM.
Some sources claim the preproduction aircraft were "Bf-109B-0s"; the 30 machines with the Schwarz propellers were "Bf-109B-1s"; and the remainder of Bertha production were "Bf-109B-2s". Other sources claim no such distinction was made at the time, with the subvariant designations later applied retroactively.
BFW couldn't make the Bf-109 fast enough to make the Luftwaffe happy. New manufacturing facilities were in construction at Augsburg, but to fill the need a license manufacturing agreement was signed with Fiesler, who began to roll out the Bf-109 from its Kassel facility in December 1937.
* By this time the improved "Jumo 210G" and "Jumo 210Ga" engines were becoming available. They featured fuel injection, a two-stage supercharger, and were rated at 700 horsepower for take-off. A Jumo 210G had been evaluated in the "Bf-109-V7", which first flew in March 1937, and late Bf-109B-2 production featured this engine fit.
The "Bf-109-V8" prototype was fitted with the Jumo 210Ga, as well as an extra pair of MG-17 7.9 millimeter guns, one in each wing with 420 RPG, for a total of four guns. A similar "Bf-109-V9" was built as well, but replaced the wing machine guns with MG-FF 20 millimeter cannon with 60 RPG.
The MG-FF cannon was suffering from teething problems at the time, and so the production "Bf-109C-1" was much like the Bf-109-V8, with four MG-17 machine guns and the Jumo 210Ga, but also added an "FuG-7" radio that permitted, for the first time in the Bf-109 series, communications with ground troops. Incidentally, the Jumo 210Ga engine was also fitted to very late production Bf-109Bs.
The first "Claras", as the C variant was called by Luftwaffe pilots, were
rolled off the production line at Augsburg in March 1938, and were rushed off
to fight in Spain.
MESSERSCHMITT BF-109C-1:
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spec metric english
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wingspan 9.87 meters 32 feet 4 inches
length 8.55 meters 28 feet 1 inches
height 2.45 meters 8 feet
empty weight 1,597 kilograms 3,522 pounds
loaded weight 2,296 kilograms 5,062 pounds
max speed at altitude 470 KPH 290 MPH / 255 KT
service ceiling 8,400 meters 27,600 feet
range 650 kilometers 405 MI / 350 NMI
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The "Bf-109C-3" was also an experimental type, like the Bf-109C-1 but featuring wing-mounted MG-FF 20 millimeter cannon instead of the wing-mounted MG-17 machine guns, and the "Bf-109C-4" was similarly like the Bf-109C-1 but had an MG-FF Motorkanone.
* While the improved Junkers Jumo engines were welcome, they still were unable to push the Bf-109 past 480 KPH (300 MPH). What Messerschmitt really wanted for the Bf-109 was the Daimler Benz 600 (DB-600) engine.
The "Bf-109-V10" prototype was originally built in a configuration much like that of the Bf-109-V8, with a Jumo 210Ga engine, but it was then refitted with a "DB-600a" engine, rated at 900 horsepower for take-off. Ernst Udet flew the reengined Bf-109-V10 at a flying meet in July 1937, in an attempt to make a new speed record, but ended up crash-landing the aircraft.
The Bf-109-V10 was replaced for powerplant testing by the "Bf-109-V11", fitted with the modestly improved "DB-600A" engine. The following "Bf-109-V12" and "Bf-109-V13" were similar, but the Bf-109-V13 was presently upgraded to the "DB-601", with 1,175 horsepower for take-off and greater reliability. The improved Bf-109-V13 set a world speed record of 610.5 KPH (379.38 MPH) in November 1937.
The DB-601 was expected to be the proper powerplant for the Bf-109. Not only was it very powerful, but it was fuel-injected and could operate effectively in negative-gee maneuvers that would cause a carbureted engine to stall. However, there were problems: working out the bugs in the new engine was proving troublesome, the automatic supercharging system proving a great nuisance; Daimler-Benz couldn't build it in the needed quantities; and priority for engine deliveries had been given to the Heinkel He-111 bomber.
* These difficulties led to the production of an interim aircraft, the "Bf-109D", using Jumo 210D and 210G powerplants that were available.
Roughly 200 Bf-109Ds, referred to as "Dora" by Luftwaffe pilots, were built, with subvariants designated "Bf-109D-1" through "Bf-109D-3" and differing in armament fit.
The Bf-109D-1 tried the three-gun armament again, with an MG-FF 20 millimeter Motorkanone, but the weapon tended to jam and still caused overheating problems, and so the Bf-109D-2 went back to the four MG-17 7.9 millimeter guns of the Bf-109C-1. The Motorkanone was also often pulled out of the Bf-109D-1 in the field.
The Bf-109D-3 traded up the wing-mounted MG-17s for MG-FF 20 millimeter cannon, a fit like that of the Bf-109C-4, but the Bf-109D-3 actually saw operational service, though it was only built in small numbers.
The Dora was sent to Spain to prove itself in combat, and young Condor Legion pilots like Adolf Galland and Werner Moelders clearly demonstrated its value. Moelders was not merely a good fighter pilot but also an excellent air tactician, and devised new fighter tactics, such as the "finger four" formation that the Germans called the "Schwarm", and a more flexible approach to air-to-air combat than was practiced by other air arms at the time. Moelders would leave Spain with 14 kills, making him the highest scorer of the campaign.
* While the evolution of the Bf-109 was in progress, there was also a significant change at BFW. The fighter had given Willy Messerschmitt international recognition, and so the RLM suggested that BFW could improve its international recognition by changing its name to "Messerschmitt AG".
Aircraft already in production by BFW would retain the "Bf" designation for the rest of their careers, but all new aircraft from the company would have the "Me" designation. The name "Messerschmitt" would become even more famous as his designs proved their worth against Germany's adversaries, and Nazi propaganda trumpeted their victories.
* The first really satisfactory version of the Bf-109 was the "Bf-109E". The Bf-109-V13, mentioned above, was the first "Bf-109E-0", and was followed by seven more Bf-109E-0s ("Bf-109-V14" through "Bf-109-V20"), with minor variations in equipment fit.
The "Bf-109-V21" and "Bf-109-V22" are stated in some sources as being Bf-109E-0s, but these two prototype numbers are also applied to the initial two "F" series prototypes, discussed in the next chapter. Duplication of the designations seems unlikely, and given the fact that earlier prototype versions underwent changes in definition, it is plausible that they started out as "E" prototypes and ended up being "F" prototypes instead.
The initial "Bf-109E-1" subvariant was first delivered to the Luftwaffe in early 1939 and featured the DB-601A-1 engine, as well as a three-bladed variable-pitch propeller. Although earlier Bf-109 variants had featured a "chin" engine radiator, the Bf-109E moved it to twin radiators, mounted one under each wing. The Bf-109E was not quite as agile as the Bf-109D but it was substantially faster, and in fact was one of the most potent fighters in the world at the time.
The Bf-109E-1 featured armament of four MG-17 7.9-millimeter machine guns, with two in the cowling and two in the wings. The cowling guns had 1,000 RPG, while the wing guns had 420 RPG.
Twenty Bf-109E-1s were turned out in time to be sent to Condor Legion in Spain before the civil war ended in March 1939. By this time, Nationalist resistance was faltering, and the new fighters met little opposition. In the end, a total of some 200 Luftwaffe pilots served with the Condor Legion, obtaining combat experience that would make Germany's fighter pilots an elite in the campaigns to come. They left the twenty Bf-109E-1s behind for the Spaniards.
Manufacture of the Bf-109E, presently referred to as the "Emil" by Luftwaffe pilots, continued to ramp up, although Messerschmitt production was shifted from Augsburg to Regensburg to make way for the Bf-110 twin-engine fighter. Other aircraft manufacturers were brought in to help feed the Luftwaffe's appetite for the Bf-109.
* By the time Germany invaded Poland in September 1939, the Luftwaffe was flying about 850 Bf-109Es and 235 Bf-109Ds. The invasion was a complete success, overwhelming Polish resistance in a rapid "Blitzkrieg (Lightning War)". A little over 200 Bf-109s participated in the invasion, with 67 being lost, mostly to ground fire. After the invasion, things went quiet again as the British and French went passive, resulting in the "Sitzkrieg (Sitting War)".
However, from the start of the war the British Royal Air Force (RAF) performed small-scale raids on German territory. These actions climaxed in the biggest air battle of 1939, on 18 December 1939, when the RAF attacked Wilhelmshaven in daylight with 24 unescorted Vickers Wellington bombers. The Luftwaffe had a party with them, shooting down 12 of the Wellingtons and damaging three others badly. The Luftwaffe lost of two Bf-109s. The British began to seriously reconsider their tactics.
Air skirmishes over the French border during the Sitzkrieg were intermittent. However, in November, a confused Luftwaffe pilot set an Emil down on the wrong side of the border, with the aircraft eventually ending up in England the following spring for flight tests and mock dogfights with British fighters. An Emil had similarly fallen into French hands back in September, but it had been lost in a mid-air collision before serious evaluation could be conducted with it.
The evaluation showed the Emil completely superior to the Hawker Hurricane in almost all respects, and generally superior to a Spitfire Mark I equipped with a two-bladed propeller. With a three-bladed Rotol propeller, the Spitfire Mark I had the upper hand at high altitude. This particular Messerschmitt is now in the RAF museum at Hendon.
* The Doras were gradually phased out as new Emil subvariants were introduced. The "Bf-109E-2" was supposed to have been fitted with the MG-FF 20 millimeter Motorkanone, but this subvariant was not actually built.
The "Bf-109E-3" featured a DB-601Aa engine with 1,200 horsepower for take-off. The Bf-109E-3 also had a stronger canopy design; armor plate in the seat and above the pilot's head; and replaced the MG-17 wing guns to MG-FF 20 millimeter cannons with 60 RPG. The bigger weapons required the design of a blister for the lower wing to accommodate them. The pilot had a selector switch to allow firing of one or both cannons.
The definitive Emil variant, the "Bf-109E-4", was very similar to the
Bf-109E-3 , but the MG-FF wing cannon were updated to MG-FF/M cannon. The
MG-FF/M was externally identical to the MG-FF, but had a "softened" recoil
mechanism to allow it to fire high-explosive "mine" shells that proved highly
effective. The softened recoil mechanism also resulted in a higher rate of
fire.
MESSERSCHMITT BF-109E-3:
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spec metric english
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wingspan 9.87 meters 32 feet 4 inches
length 8.64 meters 28 feet 4 inches
height 2.50 meters 8 feet 2 inches
empty weight 1,900 kilograms 4,190 pounds
loaded weight 2,665 kilograms 5,875 pounds
max speed at altitude 560 KPH 350 MPH / 300 KT
service ceiling 10,500 meters 34,500 feet
range 660 kilometers 410 MI / 355 NMI
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The campaign in France had suggested the need for fighter-bomber ("Jagdbomber" or "Jabo") aircraft, and a number of Bf-109s and Bf-110s were experimentally fitted with centerline bomb racks. They performed attacks on Channel shipping, and the combat tests proved so successful that the Luftwaffe decided to create Jabo Bf-109 squadrons.
The first Bf-109 Jabo subvariant, the "Bf-109E-1/B", was a field conversion of existing Bf-109E-1s, featuring a centerline rack for a single 250 kilogram (550 pound) bomb, though more normally they carried a single 50 kilogram (110 pound) bomb to achieve greater range. Bf-109-E4s were also fitted with the rack in production, this modification being given the designation "Bf-109-E4/B". These Jabo subvariants were not fitted with a bombsight as such, but the standard Revi gunsight could be used in dive attacks with some accuracy, and a line was painted on the windscreen to help the pilot with his attack.
The subject of the Bf-109's centerline rack is a confusing issue. Such racks would be fitted to subvariants or modifications of the aircraft through the rest of its evolution, allowing the carriage of a 250 kilogram (550 pound) bomb, four 50 kilogram (110 pound) bombs, or a 300 liter (80 US gallon) drop tank. However, it is very unclear whether the same rack could be alternatively fitted with all three of these stores configurations, or whether different racks handled different subsets of them. As the issue is both insignificant and difficult to resolve, this document makes no judgement on it.
* Despite the success of the Bf-109E in the French campaign, some worries cropped up. For one, the Bf-109's range had proven inadequate. For another, the Bf-109E had come up against the British Supermarine Spitfire fighter while the Luftwaffe had ineffectually tried to stop the mass evacuation of Allied troops at Dunkirk, and the British fighter had proven a formidable opponent.
These worries would become critical as the Luftwaffe shifted its attention across the English Channel. At first, things went well for the Luftwaffe. After the beginning of the Battle of Britain on 13 August 1940, the Bf-109s were allowed to range freely and engage British fighters at will, using the fluid tactics devised by Moelders in Spain. The British were trained in traditional inflexible formation tactics that put them at a disadvantage, but the RAF quickly adopted the Luftwaffe's tactics.
While the Bf-109s ranged freely, the job of protecting the bombers fell to the twin-engine Bf-110s. It didn't work. The Bf-110s were slaughtered, and so by early September the Bf-109s were ordered to operate as bomber escorts. Forced into a defensive posture, the Bf-109 was at a disadvantage relative to Hurricanes and Spitfires.
The limited range of the Bf-109 was also proving a liability, as it could not stay over the battle area for long before having to return home. After the bombings campaign was switched from British airfields to British cities, the RAF began to gain the upper hand.
The last action of the Battle of Britain was on 31 October 1940. The British had lost 631 Hurricanes, 403 Spitfires, and 115 Blenheim fighters, for a total of 1,149. The Luftwaffe lost 610 Bf-109s, along with 235 Bf-110s and 937 bombers, for a total of 1,782. Worse, many of the British pilots who had to bail out returned to battle the next day. Luftwaffe pilots who bailed out went to prisoner of war camps.
From a tactical point of view, the battle was not all that lopsided and could be regarded as a stand-off. However, it was a moral victory for the British, who had been the first to stand up to Hitler and make him back off, and a moral defeat for the Luftwaffe, who had been used to victories.
* Nonetheless, the Bf-109 was still a dangerous adversary, and its cannon armament was devastatingly effective against RAF fighters armed with rifle-caliber machine guns, another lesson the RAF would absorb. Werner Moelders was the first of Hitler's Luftwaffe pilots to exceed 50 kills, with Adolf Galland close behind him.
The Luftwaffe was still enthusiastic for the Bf-109, and new versions of the Emil were rolled out. The uprated DB-601N powerplant, with 1,200 horsepower for take-off, was fitted to the to produce the "Bf-109E-4/N" modification.
"Fighter reconnaissance" subvariants were produced, such as the "Bf-109E-5" and "Bf-109E-6", which deleted the wing guns and featured a camera in the rear fuselage. The Bf-109E-5 was fitted with the DB-601Aa engine, while the Bf-109E-6 was fitted with the uprated DB-601N engine.
A long-range fighter / Jabo variant, the "Bf-109E-7", was produced with a rack for a 300 liter (80 US gallon) centerline drop tank or 250 kilogram (550 pound) bomb. A "Bf-109E-7/U2" modification was produced for ground attack with armor protection for critical engine systems, and a "Bf-109E-7/Z" modification was built for high-altitude operation using GM-1 nitrous oxide engine boost. The nitrous oxide provided supplemental oxidizer for the engine, with the nitrous oxide bottle placed under the pilot's seat. However, the gear was heavy, and its placement disturbed the balance of the aircraft, leading to unpleasant stall-spin characteristics.
Meanwhile, in Africa, after being introduced to the theater in April 1941, the Bf-109E was enjoying the success to which it had been accustomed, racking up large numbers of kills against RAF Hurricanes and Kittyhawks. The Emil was modified for African operations by being fitted with engine sand filters and a desert survival kit. The survival kit contained food and water, a lightweight carbine, signal equipment, and other gear. The result were the "tropicalized" subvariant modifications, designated with the suffix "Trop". "Bf-109E-4/Trop", "Bf-109E-5/Trop", and "Bf-109E-7/Trop" subvariants were introduced.
The last two major subvariants of the Emil were the "Bf-109E-8" and the "Bf-109E-9". The Bf-109E-8 was similar to the Bf-109E-1 in having an armament of four MG-17 7.9 millimeter guns, but had a DB-601E engine with 1,350 horsepower for take-off, and a centerline rack for a bomb or drop tank.
The Bf-109E-9 was a long-range reconnaissance version, with a camera in the rear fuselage, two 7.9 millimeter machine guns in the cowling, and a centerline rack. Some sources claim it had the DB-601E engine and no wing guns, while others say it had the earlier DB-601N engine and an MG-FF 20 millimeter cannon under each wing. The first configuration seems slightly more plausible, since the DB-601N would have been a throwback to earlier subvariants, and wing guns were not fitted to other reconnaissance subvariants of the Bf-109. The mission did not call for heavy armament and removal of the wing guns compensated for the weight of the camera.
In any case, the Bf-109E-8 and Bf-109E-9 were only built in small quantities. They were the last of the roughly 4,000 Emils built. Luftwaffe interest had clearly moved on to something more advanced.