Messerschmitt Bf 109

Bf 109
Messerschmitt Bf 109G-10 at the National Museum of the United States Air Force in Dayton, Ohio
Role	Fighter
Manufacturer	Bayerische Flugzeugwerke Messerschmitt
Designed by	Willy Messerschmitt
First flight	29 May 1935
Introduced	1937
Retired	1945, Luftwaffe 1965, Spain
Status	Retired
Primary users	Luftwaffe Hungarian Air Force Aeronautica Nazionale Repubblicana Forţele Aeriene Regale ale României
Number built	33,984 units produced up to April 1945.[1]
Variants	Avia S-99/S-199 Hispano Aviacion Ha 1112

The Messerschmitt Bf 109 was a German World War II fighter aircraft designed by Willy Messerschmitt in the early 1930s. It was one of the first true modern fighters of the era, including such features as an all-metal monocoque construction, a closed canopy, and retractable landing gear. The Bf 109 was produced in greater quantities than any other fighter aircraft in history, with a total of 33,984 units produced up to April 1945.^[2]

The Bf 109 was the backbone of the Luftwaffe fighter force in World War II, although it began to be partially replaced by the Focke-Wulf Fw 190 from 1941. Originally conceived as an interceptor, it was later developed to fulfill multiple tasks, serving as bomber escort, fighter bomber, day-, night- all-weather fighter, bomber destroyer, ground-attack aircraft, and as reconnaissance aircraft. The Bf 109 had its faults. Like the Spitfire, it had a short range.^{[Notes 1]} Its cockpit was cramped and the track of its undercarriage very narrow indeed so that it had challenging takeoff and landing characteristics.^[3] Neverthless, it remained competitive with Allied fighter aircraft until the end of the war.

The aircraft served with several countries during the war, and with some for many years after. The Bf 109 was flown by the three top-scoring fighter aces of World War II who claimed 928 victories between them while flying with Jagdgeschwader 52, chiefly on the Eastern Front, as well as by the highest scoring German ace in the North African Campaign.^[4] "The 109 was a dream, the non plus ultra," recalled Gunther Rall the Luftwaffe ace with 275 kills. "Of course, everyone wanted to fly it as soon as possible." ^[5] It was also flown by high-scoring non-German aces, notably from Finland, Romania, Croatia and Hungary. Against Soviets, the Finnish-flown Bf 109Gs claimed a ratio of 25:1 in favour of the Finns.^[6]

Contents [hide] 1 Designation and nicknames 2 Development 2.1 Prototypes 2.2 The contest 3 Design features 3.1 Armament and gondola cannons 3.2 Records 4 Variants 4.1 Bf 109 A/B/C/D 4.2 Bf 109E "Emil" 4.2.1 E-1 4.2.2 E-2 4.2.3 E-3 4.2.4 E-4 4.2.5 E-5, E-6 4.2.6 E-7 4.3 Bf 109E in the Battle of Britain 4.4 Bf 109F "Friedrich" 4.4.1 Prototypes 4.4.2 Aerodynamic improvements 4.4.3 Armament 4.4.4 Bf 109F variants and sub-variants 4.4.4.1 F-0, F-1, F-2 4.4.4.2 F-3, F-4, F-5, F-6 4.5 Bf 109G "Gustav" 4.5.1 Introduction 4.5.2 Early Bf 109G models 4.5.2.1 G-1, G-2 4.5.2.2 G-3, G-4 4.5.2.3 G-5, G-6 4.5.3 Late Bf 109G models 4.5.3.1 Improvements to the design 4.5.3.2 Late-production G-6, G-14, G-14/AS 4.5.3.3 G-10 4.5.3.4 Miscellaneous variants: G-8, G-12 4.6 Bf 109H 4.7 Bf 109K "Kurfürst" 4.7.1 K-4 4.7.2 Other Bf 109K projects and prototypes 4.8 Bf 109T "Trägerflugzeug" (carrier aircraft) 4.9 Bf 109Z "Zwilling" 4.10 Developments after World War II 4.10.1 Czechoslovak production 4.10.2 Spanish production 5 Bf 109 production 6 Operational History 7 Operators 8 Specifications (Bf 109 G-6) 9 See also 10 References 10.1 Footnotes 10.2 Citations 10.3 Bibliography 11 External links

[edit] Designation and nicknames

Originally the aircraft was designated as Bf 109 by Reichsluftfahrtministerium (German Aviation Ministry, RLM), since the design was submitted by the Bayerische Flugzeugwerke (literally "Bavarian Aircraft Factory") company. However, the company was renamed Messerschmitt AG after July 1938^[7] when Erhard Milch finally allowed Willy Messerschmitt to acquire the company. Subsequently, all Messerschmitt aircraft that originated after that date, such as the Me 210, were to carry the "Me" designation. Despite regulations by the RLM, wartime documents from Messerschmitt AG, RLM and Luftwaffe loss and strength reports continued to use both designations, sometimes even on the same page.^[8] All extant airframes are described as "Bf 109" on identification plates, including the final K-4 models,^[9] with the noted exception of aircraft either initially built or re-fitted by Erla Flugzeugwerke, which sometimes bore the Me 109 stamping. "Me-109" is usually pronounced in German as may hundert-neun ("hundred-nine") while English-speakers usually say "emm ee one-oh-nine".

The aircraft was given several nicknames by its operators and opponents, generally derived from the name of the manufacturer (Messer, Mersu, Messzer etc.), or the external appearance of the aircraft: the G-6 variant was nicknamed by Luftwaffe personnel as Die Beule ("The bump/bulge") because of the cowling's characteristic covers for the breeches of the later Bf 109G's synchronized 13 mm (.51 in) MG 131 machine guns, while Soviet aviators nicknamed it as "the skinny one" for its sleek appearance (compared to the more robust Fw 190). The names "Anton", "Bertha", "Caesar", "Dora", "Emil", "Friedrich", "Gustav" and "Kurfürst" were derived from the variant's official letter designation (i.e. Bf 109G – 'Gustav'), based on the German phonetic alphabet of World War II;^{[Notes 2]} a practice that was also used for other German aircraft designs.

[edit] Development

During 1933, the Technisches Amt (T-Amt), the technical department of the RLM, concluded a series of research projects into the future of air combat. The result of the studies was four broad outlines for future aircraft:^[10]

• Rüstungsflugzeug I for a multi-seat medium bomber
• Rüstungsflugzeug II for a tactical bomber
• Rüstungsflugzeug III for a single-seat fighter
• Rüstungsflugzeug IV for a two-seat heavy fighter

Bf 109 in flight

Rüstungsflugzeug III was intended to be an interceptor, replacing the Arado Ar 64 and Heinkel He 51 biplanes then in service. Two months after the newly elected national socialist government were sworn to power on the 30 January 1933, the RLM published the tactical requirements for a single-seat fighter in the document L.A. 1432/33.^[11]

The fighter needed to have a top speed of 400 km/h (250 mph) at 6,000 m (19,690 ft) which it could maintain for 20 minutes, while staying in the air for a total of 90 minutes. The critical altitude of 6,000 metres was to be reached in no more than 17 minutes, and the fighter was to have an operational ceiling of 10,000 metres.^[12] Power was to be provided by the new Junkers Jumo 210 engine of about 522 kW (700 hp). It was to be armed with either a single high-performance 20 mm MG C 30 cannon firing through the engine shaft or, alternatively, either two engine cowl-mounted 7.92 mm (.312 in) MG 17 machine guns, or one lightweight, engine-mounted 20 mm MG FF cannon with two 7.92 mm MG 17s.^[13] One other specification was that the aircraft needed to keep wing loading below 100 kg/m². The performance was to be evaluated based on the fighter's level speed, rate of climb, and manoeuvrability, in that order.^[14]

In fact, the R-III specifications were not actually devised by the T-Amt: in early-1933, both Heinkel and Arado had sent in privately funded designs for a monoplane fighter, and the T-Amt simply collected the best features from both and sent them back out again, adding Focke-Wulf to the inivtation to tender.

It has been suggested that Willy Messerschmitt was originally not invited to participate in the competition due to personal animosity between Messerschmitt and RLM director Erhard Milch;^{[Notes 3]} however, recent research by Willy Radinger and Walter Shick indicates that this may not have been the case, as all three competing companies – Arado, Heinkel and the BFW – received the development contract for the L.A. 1432/33 requirements at the same time in February 1934.^[15] A fourth company, Focke Wulf received a copy of the development contract only in September 1939.^[15] The powerplant was to be the Junkers Jumo 210, but the proviso was made that it would be interchangeable with the more powerful, but less developed Daimler-Benz DB 600 powerplant.^[16] Each was asked to deliver three prototypes to be delivered for head-to-head testing in late 1934.

[edit] Prototypes

Messerschmitt Bf 109 V1

Design work on what was to become the Bf 109 began in March 1934, just three weeks after the development contract was awarded, under Messerschmitt Project number P.1034. The basic mock-up was completed by May 1935, and a more detailed design mock-up was prepared by January 1935. The design was issued with the RLM's designation of "Bf 109", with the 109 next in line from a batch of type numbers assigned to BFW.^[15]

The first prototype (Versuchsflugzeug 1 or V1), with the civilian registration D-IABI, was completed by May 1935, but the German engines were not yet ready. In order to get the 'RIII' designs into the air, the RLM acquired four Rolls-Royce Kestrel VI engines by trading Rolls-Royce a Heinkel He 70 Blitz as an engine test-bed.^{[Notes 4]} Messerschmitt received two of these engines and started adapting the engine mounts of V1 to take the V-12 engine upright. This work was completed in August, and V1 completed flight tests in September 1935. The aircraft was then sent to the Luftwaffe test centre at Rechlin to take part in the design contest. By late-summer, the Jumo engines were starting to become available, and V2 was completed with the 449 kW (600 hp) Jumo 210A in October 1935. V3 followed, being the first to actually mount guns, but another Jumo 210 was not available and it ended up delaying the flight of V3 until May 1936.

[edit] The contest

After Luftwaffe acceptance trials were completed at Rechlin, the prototypes were moved to Travemünde for the head-to-head portion of the contest. The aircraft which participated in the trials were the Arado Ar 80 V3, the Focke-Wulf Fw 159 V3, the Heinkel He 112 V4 and the Bf 109 V2. The He 112 arrived first, in early February 1936, and the rest of the prototypes had all arrived by the beginning of March.

Because most of the fighter pilots of the Luftwaffe were used to biplanes with open cockpits, low wing loading, light g-forces and easy handling, they were very critical of the Bf 109 at first. However, it soon became one of the front-runners in the contest, as the Arado and Focke-Wulf entries, which were intended as "back-up" programmes to safeguard against failure of the two favourites, proved to be completely outclassed. The Arado Ar 80, with its gull wing (replaced with a straight, tapered wing on the V3) and fixed, spatted undercarriage was overweight and underpowered and the design was abandoned after three prototypes had been built. The parasol winged Fw 159 was always considered by the Erprobungsstelle (E-Stelle) staff at Travemünde to be a compromise between the biplane and the aerodynamically more efficient low-wing monoplane. Although it had some advanced features, it used a novel undercarriage design which was never truly reliable.^[17]

JG 53 Bf 109E-1, c. 1939/1940

Initially, the Bf 109 was regarded with suspicion by the E-Stelle test pilots because of its steep ground angle, resulting in poor forward view on the ground; the sideways-hinged cockpit canopy, which could not be opened in flight; and the automatic wing leading edge slots which, it was thought, would inadvertently open during aerobatics, possibly leading to crashes. They were also concerned about the high wing loading.^[18]

The Heinkel He 112, based on a scaled-down Blitz was the favourite of the Luftwaffe leaders. Compared with the Bf 109, it was also cheaper.^[19] Positive aspects of the He 112 included the wide track and robustness of the undercarriage, considerably better visibility from the cockpit, and a lower wing loading that led to easier landings. However, the He 112 was also structurally complicated, being some 18% heavier than the Bf 109, and it soon became clear that the thick wing, which spanned 12.6 m (41 ft 4 in) with an area of 23.2 m² (249.7 ft²) on the first prototype (V1), was a disadvantage for a light fighter, decreasing the aircraft's rate of roll and manoeuvrability. Because of its smaller, lighter airframe, the Bf 109 was 30 km/h (20 mph) faster than the He 112 in level flight, and superior in climbing and diving. As a result, the He 112 V4 which was used for the trials had new wings, spanning 11.5 m (37 ft 8.75 in) with an area of 21.6 m² (232.5 ft²). In addition, the V4 had a single-piece, clear-view, sliding cockpit canopy and a more powerful Jumo 210Da engine with a modified exhaust system. However, the improvements had not been fully tested and the He 112 V4 could not be demonstrated in accordance with the rules laid down by the Acceptance Commission, giving a distinct advantage to the Bf 109. The Commission ruled in favour of the Bf 109 because of the Messerschmitt test pilot's demonstration of the 109's capabilities during a series of spins, dives, flick rolls and tight turns, throughout which the pilot was in complete control of the aircraft.^[20]

In March, the RLM received news that the British Spitfire had been ordered into production; with this information, a quick result to the contest was needed in order to get the winning design into production. On 12 March, they released a document that outlined the results of the contest, Bf 109 Priority Procurement, as a result of which the RLM instructed Heinkel to radically re-design the He 112, while ordering the Bf 109 into production.^[21]

[edit] Design features

As with the earlier Bf 108, the new design was based on Messerschmitt's "lightweight construction", which essentially aimed at reducing the total number of parts in the aircraft as much as possible. Examples of this could be found in the use of two large, complicated brackets which were fitted to the main engine firewall; these brackets incorporated the lower engine mounts and landing gear pivot points. Another large forging attached to the firewall carried the main-spar pick up points, and carried most of the wing loads. Contemporary design practice was usually to have these main load-bearing structures mounted on different parts of the airframe, with the loads being distributed through the main structure via a series of strong-points. By centralising the loads on the main bulkhead, the main structure of the 109 was able to be made relatively light and uncomplicated.^[22]

Another advantage of this design was that because the outboard-retracting main landing gear, retracting through roughly an 85º angle, was attached to the fuselage, it was possible to completely remove the wings of the aircraft for major servicing without the need for additional equipment to support the fuselage. It also meant that the wing structure was able to be simplified through not having to carry the weight of the aircraft and not having to bear the loads imposed during takeoff or landing. However, this had one major drawback — this landing gear arrangement ensured a narrow wheel track making the aircraft laterally unstable while on the ground. To increase stability the legs had to be splayed out, creating another problem in that loads imposed during takeoff and landings were transferred at an angle up the legs. The small rudder of the 109 was relatively ineffective at controlling the strong swing created by the powerful slipstream of the propeller, and this sideways drift created disproportionate loads on the wheel opposite the swing. If the forces imposed were large enough, the pivot points often broke and the landing gear leg would be forced sideways into its bay.^[23] Because of the large ground angle caused by the long legs, visibility for the pilot, especially straight ahead, was very poor, a problem exacerbated by the sideways-opening canopy. This meant that the pilots often had to "snake" the aircraft during taxiing manoeuvres, which again imposed stresses on the splayed undercarriage legs. Ground accidents were, however, more of a problem with rookie pilots, especially during the later stages of the war.^[24] Even experienced pilots, especially those who were tired, were caught out. Most Finnish pilots reported that the swing was easy to control, but some of the less-experienced pilots lost fighters on startup.^[24] At least 10% of all Bf 109s went lost in takeoff and landing accidents, 1,500 of which occurred between 1939 and 1941. ^[25]

The provision of a fixed "tall" tailwheel on some of the late G-10s and 14s and the K-series helped alleviate the problem to a large extent.^[26]

Automatic leading edge slats on a Bf 109E. By using high-lift devices, the handling qualities of the Bf 109 were considerably enhanced.

Right from the inception of the design priority was given to total and easy access to the powerplant, fuselage weapons and other systems while the aircraft was operational from forward airfields. To this end, the entire engine cowling was made up of large, easily removable panels which were secured by large toggle-latches. A large panel under the wing centre-section could be removed to gain access to the L-shaped main fuel tank, which was sited partly under the cockpit floor and partly behind the rear cockpit bulkhead. Other, smaller panels gave easy access to the cooling systems and electrical equipment. The engine was held in two large, forged, magnesium alloy Y-shaped legs which were cantilevered from the main firewall/bulkhead. Each of the legs was secured by two quick-release screw fittings on the main firewall. All of the main pipe connections were colour-coded and grouped in one place, where possible, and the electrical equipment plugged into junction boxes mounted on the firewall. The entire powerplant could be removed or replaced as a unit in a matter of minutes.^[27]

An aspect of this construction technique was the use of a single, I-section main spar in the wing, mounted close to the leading edge, thus forming a stiff D-shaped torsion box. Most aircraft of the era used two spars, near the front and rear edges of the wings, but the D-box was much stiffer torsionally, and eliminated the need for the rear spar. The wing profile was somewhere between NACA 2314 and 2315, with a thickness to chord ratio of 14.5%. Another major difference was the higher wing loading than the competing designs. While the R-IV contract called for a wing loading of less than 100 kg/m², Messerschmitt felt this was unreasonable; with the engines available to them, the fighter would end up slower than the bombers it was tasked with catching. Since the fighter was being designed primarily for high-speed flight, a smaller wing area would be optimal for achieving high level speeds, but the downside of such a trade-off was that low-speed flight would suffer, as the smaller wing would require more airflow to generate enough lift to stay flying. To compensate for this, the Bf 109 included advanced high-lift devices on the wings, including automatically opening leading edge slats, and fairly large camber-changing flaps on the trailing edge. Messerschmitt also included ailerons (and later radiator flaps) that "drooped" when the flaps were lowered thereby increasing the effective flap area. When deployed, these devices effectively increased the coefficient of lift, making it better at low speeds and high angles of attack.^[28]

[edit] Armament and gondola cannons

A cannon-armed Bf 109E, showing the 20 mm MG FF installations in the wing to good effect

Reflecting Messerschmitt's belief in low-weight, low-drag, simple monoplanes, the armament was placed in the fuselage: two synchronized machine guns, just as in a typical biplane fighter like the Albatros D.Va, were mounted in the cowling, firing over the top of the engine and through the propeller arc. As an alternative, a single high-performance cannon (or 'shell-gun', as sometimes referred in the 1930s) firing through the cylinder banks through a blast tube, with the engine buffering the recoil was considered from the start.^[29] This was also the choice of armament layout on some contemporary French monoplane fighters, such as the Dewoitine D.520.^{[Notes 5]} Conforming to Prof. Messerschmitt's ethos, this kept his gun-free wings very thin and lightweight.

When it was discovered in 1937 that the RAF was planning eight-gun batteries for its new monoplane fighters - the Hawker Hurricane and Supermarine Spitfire) - it became clear the Bf 109 would need to carry more weaponry; a new wing was designed to carry machine guns, and later, 20 mm MG FF cannon configurations. The problem was that when it came to fitting additional armament, the only place in which it could be located was in the wings. However, the positions of the undercarriage bays, main spar and wing slats meant that room was limited to two bays between the undercarriage and slats. There was room for only one weapon per wing, either a 7.92 mm MG 17 machine gun, or a 20 mm MG FF or MG FF/M cannon. The first version of the 109 to have wing guns was the C-1, which had one MG 17 per wing fitted in the inner bays. To avoid redesigning the wing to accommodate large ammunition boxes and access hatches, an unusual ammunition feed was devised whereby a continuous belt holding 500 rounds was fed along chutes out to the wing tips. The belt was fed around a roller and back along the wing, forward and beneath the gun breech, to the wing root where it was fed around another roller and back to the weapon. The gun barrels were buried in long, large diameter tubes between the spar and the leading edge. These tubes channelled cooling air around the barrels and breeches and out of a slot at the rear of the wing diaphragm and top of the flap. Room was still so restricted that parts of the MG 17's breech mechanism poked into an accommodating hole in the flap structure.^[31] The much longer and heavier MG FF had to be mounted in the outer bay. A large hole was cut through the spar webbing to allow the cannon to be fitted with an ammunition feed forward of the spar, with the rear breech block projecting through the spar. The 60-round ammunition drum was placed in the machine-gun compartment; a small hatch incorporating a blister was needed in the wing lower surface to allow access to change the drum. The entire weapon could be removed for servicing by removing a leading edge panel.^[31]

The 'black men' manhandle a Bf 109 G-6 'Kanonenvogel' equipped with the Rüstsätz VI underwing gondola cannon kit to position. Note the slats being on the port wing. France, JG 2, autumn of 1943.

From the 109F-series onwards, guns were no longer carried inside the wings – a noteworthy exception was Adolf Galland's field-modified Bf 109 F-2, which had a 20 mm MG FF/M installed internally in each wing.^{[Notes 6]} Only some of the late 109K-series models, such as the K-6, were planned to carry 30 mm (1.18 in) MK 108 cannons in the wings.^[32]

In place of internal wing armament, additional firepower was provided through a pair of 20 mm MG 151/20 cannons in conformal gun pods, installed under the wings. Although the additional armament increased the fighter's potency as a bomber destroyer, it had an adverse affect on the handling qualities, reducing its competence in fighter-versus-fighter combat and accentuating the tendency of the fighter to swing pendulum-fashion in flight.^[33] The conformal gun pods, without ammunition, weighed 135 kg (298 lb);^[34] and 135 to 145 rounds were provided per gun.^[35] The total weight, including ammunition, was 215 kg.<^[34] Installation of the underwing gun pods was a simple task that could be quickly performed by the unit's armourers, and imposed a reduction of speed of only 8 km/h (5 mph).^[36] By comparison, the installed weight of a similar armament of two 20 mm MG 151/20 cannon inside the wings of the FW 190A-4/U8 was 130 kg (287 lb), without ammunition.^[37]

[edit] Records

On 11 November 1937, Messerschmitt regained some favour with Erhard Milch when the Bf 109 V13 increased the world air speed record for Landplanes with piston engines^{[Notes 7][38]} to 610.55 km/h (379.38 mph). The "V13" had been fitted with a special racing DB 601R engine that could deliver 1,650 hp (1,230 kW) for short periods.^[39]

Heinkel, having had the He 112 rejected began work on the He 100. On 6 June 1938, the He 100 V3, flown by Ernst Udet, established a new record of 634.7 km/h (394.4 mph), and later, on 30 March 1939, test pilot Hans Dieterle surpassed that record, reaching 746.61 km/h (463.92 mph) with the He 100 V8. Messerschmitt soon regained the lead in this race. On 26 April 1939, Flugkapitän Fritz Wendel, flying the Me 209 V1, raised the figure to 755.14 km/h (469.22 mph). This was a racing aircraft having little in common with the Bf 109, powered by the DB 601ARJ, producing 1,156 kW (1,550 hp) but capable of reaching 1,715 kW (2,300 hp). For propaganda purposes, the machine was called the Bf 109R, suggesting it was just another version of the standard fighter. This world record for a propeller-driven aircraft was to stand until 1969.^[40]

[edit] Variants

[edit] Bf 109 A/B/C/D

Bf 109Cs of 1/JG 137, August/September 1939

109B

109C

The Bf 109A was the first version of the Bf 109. Armament was initially planned to be only two cowl-mounted 7.92 mm (.312 in) MG 17 machine guns. However, possibly due to the introduction of the Hurricane and Spitfire, each with eight 7.7 mm (.303 in) machine guns, experiments were carried out with a third machine gun firing through the propeller shaft.^[41] V4 and some A-0 were powered by a 640 PS (631 hp, 471 kW) Jumo 210B engine driving a two-blade fixed-pitch propeller, but production was changed to the 670 PS (661 hp, 493 kW) Jumo 210D as soon as it became available. The A-0 were not of a uniform type but saw several changes in their appearance. Visible changes included engine, cockpit and machine gun ventilation holes/slats, and the location of the oil cooler was changed several times to prevent overheating. Many of these Bf 109 A-0 served with the Legion Condor and were often misidentified as B-series aircraft, and probably served in Spain with the tactical markings 6-1 to 6-16. One A-0, marked as 6-15, ran out of fuel and was forced to land behind enemy lines. It was captured by Republican troops on 11 November 1937 and later transferred to the Soviet Union for a closer inspection.^[42] 6-15 incorporated several improvements from the Bf 109B production program and had been prepared to use a variable-pitch propeller although it had not been installed.

According to RLM documentation 22 aircraft were ordered and delivered with V4 as the A-series prototype.^[43][44]

The first Bf 109 in serial production, the Bf 109B , was fitted with the 670 PS (661 hp, 493 kW) Jumo 210D engine driving a two-bladed fixed-pitch propeller. During the B-1 production run a variable pitch propeller was introduced and often retrofitted to older aircraft; these were then unofficially known as B-2s. Both versions saw combat with the Legion Condor during the Spanish Civil War, although it was apparent that the armament was still inadequate. Several aircraft were produced with an engine-mounted machine gun but it was very unreliable, most likely because of engine vibrations and overheating. Thus the Bf 109 V8 was constructed to test the fitting of two more machine guns in the wings; however, results showed that the wing needed strengthening.^[45] In the following V9 prototype both wing guns were replaced by 20 mm MG FF cannons.^[46]

A total of 341 Bf 109B of all versions were built by Messerschmitt, Fieseler, and Erla.^[47][48]

The short-lived Bf 109C was powered by a 700 PS (690 hp, 515 kW) Jumo 210G engine with direct fuel injection. Another important change was a strengthened wing, now carrying two more machine guns giving four 7.92 mm (.312 in) MG 17s in total. The C-0 were pre-production aircraft, the C-1 was the production version, and the C-2 was an experimental version with an engine-mounted machine gun. The C-3 was planned with 20 mm MG FF cannons replacing the two MG 17s in the wings, but it is not known how many C-3 (if any) were built or converted. The C-4 was planned to have an engine-mounted MG FF, but the variant was not produced.^[49]

A total of 58 Bf 109C of all versions were built by Messerschmitt.^[47][48]

The next model, the V10 prototype, was identical to the V8, except for its Jumo 210G engine. The V10, V11, V12 and V13 prototypes were built using Bf 109B airframes, and tested the DB600A engine with the hope of increasing the performance of the aircraft. The DB600A was dropped as the improved DB601A with direct fuel injection was soon to become available.

Bf 109D

Developed from the V10 and V13 prototypes, the Bf 109D was the standard version of the Bf 109 in service with the Luftwaffe during the period just before World War II. Despite this, the type saw only limited service during the war, as all of the 235 Bf 109D still in service at the beginning of the Poland Campaign were rapidly taken out of service and replaced by the Bf 109E, except in some night fighter units where some examples were used into early-1940. Variants included D-0 and D-1 models, both having a Junkers Jumo 210D engine and armed with two wing-mounted and two nose-mounted 7.92 mm (.312 in) MG 17s.^[40] The D-2 was an experimental version with an engine-mounted machine gun, but as previously tried, this installation failed. The D-3 was similar to the C-3 but with two 20 mm MG FFs in the wings.

A total of 647 Bf 109D of all versions were built by Focke-Wulf, Erla, Fieseler, Arado and AGO.^[48][50] Messerschmitt is listed as having produced only four Bf 109D, probably the D-0 preproduction series with the serial production transferred to licensed manufacturers. Several Bf 109D were sold to Hungary and Switzerland.

[edit] Bf 109E "Emil"

In late 1938, the "Emil" entered production. To improve on the performance afforded by the rather small 447-522 kW (600-700 hp) Jumo, the larger Daimler-Benz DB 601A engine was used, yielding an extra 223 kW (300 hp) at the cost of an additional 181 kg (400 lb). To test the new 1,100 PS (1,085 hp, 809 kW) DB601A engine, two more prototypes (V14 and V15) were built, each differing in their armament. While the V14 was armed with two 7.92 mm (.312 in) MG 17s above the engine and one 20 mm MG FF in each wing, the V15 was fitted with the two MG 17s mounted above the engine only.^[51] After test fights the V14 was considered more promising and a pre-production batch of 10 E-0 was ordered. Batches of both E-1 and E-3 variants were shipped to Spain for evaluation, and received their baptism of fire in the final phases of the Spanish Civil War.

Bf 109E-3

[edit] E-1

The production version E-1 kept two 7.92 mm (.312 in) MG 17s above the engine and two more in the wings. Later, many were modified to the E-3 armament standard. The E-1B was a small batch of E-1s becoming the first operational Bf 109 fighter bomber, or Jagdbomber (usually abbreviated to Jabo). These were fitted with either an ETC 250 bomb rack, carrying one 250 kg (550 lb) bomb, or two ETC 50 bomb racks, each carrying a 50 kg (110 lb) bomb under both wings. The E-1 was also fitted with the Reflexvisier "Revi" gunsight. Communications equipment was the FuG 7 Funkgerät 7 (radio set) short-range radio apparatus, effective to ranges of 48–56 km (30–35 mi). A total of 1,183 E-1 were built, 110 of them were E-1/B.^[48][50]

[edit] E-2

Only very limited numbers of the E-2 variant were built, for which the V20 prototype served as basis. It was armed with two wing mounted, and one engine mounted MG FF cannon, which gave considerable trouble in service, as well as two MG 17s cowl machineguns. In August 1940, II./JG 27 was operating this type.^[52][53]

[edit] E-3

To improve the performance of the Bf 109E, the last two real prototypes, V16 and V17 were constructed. These received some structural improvements and more powerful armament. Both were the basis of the Bf 109 E-3 version. The E-3 was armed with the two MG 17s above the engine and one MG FF cannon in each wing.^[24][54] A total of 1,276 E-3 were built, including 83 E-3a export versions.^[50][55]

Bf 109E-4

[edit] E-4

The E-3 was replaced by the E-4 (with many airframes being upgraded to E-4 standards starting at the beginning of the Battle of Britain) which was different in some small details, most notably by using the modified 20 mm MG-FF/M wing cannon and having improved head armor for the pilot. With the MG FF/M it was possible to fire a new and improved type of explosive shell, called Minengeschoß (or 'mine-shell') which was made using drawn steel (the same way brass cartridges are made) instead of being cast as was the usual practice. This resulted in a shell with a thin but strong wall, which had a larger cavity in which to pack a much larger explosive charge than was otherwise possible. The new shell required modifications to the MG FF's mechanism due to the different recoil characteristics, hence the MG FF/M designation.

The cockpit canopy was also revised to an easier-to-produce, "squared-off" design, which also helped improve the pilot's field of view. This canopy, which was also retrofitted to many E-1s and E-3s, was largely unchanged until the introduction of a welded, heavy-framed canopy on the G series in the autumn of 1942. The E-4 would be the basis for all further Bf 109E developments. Some E-4 and later models received a further improved 1,175 PS (1,159 hp, 864 kW) DB601N high-altitude engine; known as the E-4/N this first appeared in July 1940. The E-4 was also available as a fighter-bomber with equipment very similar to the previous E-1/B. It was known as E-4/B (DB 601Aa engine) and E-4/BN (DB 601N engine). A total of 561 of all E-4 versions were built,^[50] including 250 E-4, 20 E-4/N, 211 E-4/B and 15 E-4/BN.^[55]

[edit] E-5, E-6

The E-5 and E-6 were both reconnaissance variants with a camera installation behind the cockpit. The E-5 was a reconnaissance variant of the E-3, the E-6 was a reconnaissance variant of the E-4/N. Twenty-nine E-5s were built and nine E-6 were ordered.^[55]

[edit] E-7

The E-7 was the next major production variant, entering service and seeing combat at the end of August 1940.^[56] One of the limitations of the earlier Bf 109E was their short range of 660 km (410 mi) and limited endurance, as the design was originally conceived as a short-range interceptor. The E-7 rectified this problem as it was the first subtype to be able to carry a drop tank, usually a 300 L (80 US gal) capacity unit mounted on a rack under the fuselage, which increased their range to 1,325 km (820 mi). Alternatively, a bomb could be fitted and the E-7 could be used as a Jabo fighter-bomber. Previous Emil subtypes were progressively retrofitted with the necessary fittings for carrying a drop tank from October 1940.^[57] Early E-7s were fitted with the 1,100 PS DB 601A or 1,175 PS DB 601Aa engine, while late-production ones received 1,175 PS DB 601N engines with improved altitude performance – the latter was designated as E-7/N.^[58] A total of 438 E-7s of all variants were built.^[59]

[edit] Bf 109E in the Battle of Britain

The E-1 and E-4 variants experienced the most action during the Battle of Britain. On 31 August 1940, fighter units (excluding JG 77) reported 375 E-1s, 125 E-3s, 339 E-4s and 32 E-7s on strength, indicating that most of the E-3s had been already converted to E-4 standard.^[56] By July, one Gruppe (Wing) of JG 26 was equipped with the Bf 109 E-4/N model of improved performance, powered by the new DB 601N engine using 100 octane aviation fuel.^[58]

The fuel-injected DB 601 proved most useful against the British Supermarine Spitfire and Hawker Hurricane, as the British fighters used gravity-fed carburetted engines, which would cut-out under negative g-forces whereas the DB601 did not. The Bf 109s thus had the initial advantage in dives, either during attack or to escape. The Spitfire proved a formidable opponent however, being approximately as fast and able to out-turn the 109 at medium to high speeds. On the question of comparative turning circles in combat, Spitfires and Hurricanes benefited from their lower wing loading compared with the Bf 109: the Royal Aircraft Establishment estimated the Spitfire's turning circle – without height loss – as 212 m (700 ft) in radius (the Hurricane's would be slightly tighter) while the 109E's was estimated as 270 m (890 ft) radius at 3,657 m (12,000 ft).^[60] Reports by Messerschmitt A.G. on the other hand give the smallest turning circle as 170 m,^[61] and fighter pilots on both sides claim they would out-turn their opponents in combat. Radinger and Schick, quoting the 1939 Luftwaffe specifications for the Bf 109E, state the tightest turn radius at ground level as 125 m (410 ft), and as 230 m (754 ft) at 6,000 m (19,690 ft).^[61][62] The most experienced fighter aces like Werner Mölders were the first ones to fly the first Bf 109 F-1s in combat in October 1940.^[63]

In the Battle of Britain, the Bf 109 was at a disadvantage due to its short range: like most of the 1930s monoplane interceptors, it was designed to engage enemy bombers over friendly territory, and the range and endurance necessary for escorting long-ranged bombers over enemy territory was not required. During the Battle, after escorting bombers from their bases in northern France, The Netherlands and Germany, the Messerschmitt had only around 15 minutes of fuel for combat over southern England before having to turn back. The Spitfire and Hurricane, designed with similar operational requirements in mind, but operating virtually over their home airfields, had a tactical advantage in being able to remain longer in the combat area and having the option to pursue any targets if needed. The approach to firepower was radically different: the RAF had not yet developed cannon-armed fighters and instead used massed batteries of rifle-caliber guns, with the Spitfire and Hurricane having eight 7.7 mm (.303 in) machine guns, while the Bf 109s (E-3, E-4, E-7) carried two 7.92 mm (.312 in) MG 17s and two 20 mm MG FF cannon. The latter fired explosive shells which were highly destructive, and had different ballistic properties to the cowl-mounted MG 17s, but were carried in limited numbers due to their being stowed in a replaceable (on the ground) 60-round capacity drum magazine attached to each cannon. The E-1s on the other hand carried only four 7.92 mm (.312 in) MG 17s, but provided with a total of 4,000 rounds.

RAF pilots who tested captured Bf 109s liked the engine and throttle response, the docile and responsive handling and stall characteristics at low speeds, but criticised the high-speed handling characteristics, poorer turning circle, and great control forces required at speed.^[60][64] In August 1940, comparative trials were held at the E'Stelle Rechlin, with the famous ace Werner Mölders being one of the participants. The tests concluded that the Bf 109 had superior level and climb speed to the Spitfire at all altitudes, but also noted the significantly smaller turning circle of the British fighter. It was advised not to engage in turning dogfights unless the performance advantage of the Bf 109 could be used to full effect. The roll rate of the Bf 109 was deemed superior as was its stability on target approach. Mölders himself called the Spitfire "miserable as a fighting aircraft", due to its two-pitch propeller and the inability of its carburettor to handle negative g-forces. It should be noted, however, that in the political climate of the times there was often a considerable amount of propaganda written into such reports by both sides.^[65]

Bf 109E variants and sub-variants

• E-0 (Pre-production aircraft with 4 × 7.92 mm/.312 in MG 17 machine guns)
• E-1 (Similar to E-0)
  • E-1/B (Fighter-bomber version of E-1, usually with DB 601Aa)
• E-2 (Limited production, additonal engine mounted MG FF cannon, otherwise as E-3)
• E-3 (Similar to E-1 but 2 × 20 mm MG FFs in the wings instead of the MG 17)
• E-4 (Armor and structural improvements, change of MG FF cannons to MG FF/M. "Square" canopy)
  • E-4/B (Fighter-bomber version of E-4, 1 × 250 kg/550 lb bomb, usually with DB 601Aa)
  • E-4 trop (Version of E-4 modified to serve in tropical regions)
  • E-4/N (E-4 with DB601N engine)
  • E-4/BN (Fighter-bomber version of E-4/N, 1 × 250 kg/550 lb bomb)
• E-5 (Recon version of E-3, camera equipment, 2 × 7.92 mm/.312 in MG 17)
• E-6 (Recon version of E-4/N, camera equipment, 2 × 7.92 mm/.312 in MG 17)
• E-7 (Similar to E-4 but with optional 300 L drop tank)
  • E-7/N (Similar to E-4/N but with optional 300 L tank)
  • E-7/NZ (also known as E-7/Z, an E-7/N with additional GM-1 nitrous oxide injection system)
  • E-7/U2 (Ground attack variant of E-7 with additional armor)
• E-8 (Long-range version of E-1 using drop tank installation of E-7, 4 × 7.92 mm/.312 in MG 17)
• E-9 (Recon version of E-7/N, drop tank, camera equipment, 2 × 7.92 mm/.312 in MG 17)

[edit] Bf 109F "Friedrich"

Messerschmitt Bf 109 F-2

[edit] Prototypes

Development of the new Bf 109F airframe had begun in 1939. After February 1940 an improved engine, the Daimler-Benz DB 601E, was developed for use with the Bf 109. The engineers at the Messerschmitt facilities took two Bf 109 E-1 airframes and installed this new powerplant. The first two prototypes, V21 (Werksnummer (Works number) or W.Nr 5602) and V22 (W.Nr 1800) kept the trapeziform wing shape from the E-1, but the span was reduced by 61 cm (2 ft) by "clipping" the tips. Otherwise the wings incorporated the cooling system modifications described below. V22 also became the testbed for the pre-production DB 601E. The smaller wings had a detrimental effect on the handling so V23, Stammkennzeichen (factory Code^{[Notes 8]}) CE+BP, W.Nr 5603, was fitted with new, semi-elliptical wingtips. The fourth prototype, V24 VK+AB, W.Nr 5604, flew with the clipped wings but featured a modified, "elbow"-shaped supercharger air-intake which was eventually adopted for production, and a deeper oil cooler bath beneath the cowling.^[66] On all of these prototypes the fuselage was cleaned up and the engine cowling modified to improve aerodynamics.

[edit] Aerodynamic improvements

Compared to the earlier Bf 109E, the Bf 109F was much improved aerodynamically. The engine cowling was redesigned to be smoother and more rounded. The enlarged propeller spinner, adapted from that of the new Messerschmitt Me 210, now blended smoothly into the new engine cowling.^[67] Underneath the cowling was a revised, more streamlined oil cooler radiator and fairing. A new ejector exhaust arrangement was incorporated, and on later aircraft a metal shield was fitted over the left hand banks to deflect exhaust fumes away from the supercharger air-intake. The supercharger air-intake was, from the F-1 -series onwards, a rounded, "elbow"-shaped design that protruded further out into the airstream. A new three-blade, light-alloy VDM propeller unit with a reduced diameter of 3 m (9 ft 8.5 in) was used. Propeller pitch was changed electrically, and was regulated by a constant-speed unit, though a manual override was still provided. Thanks to the improved aerodynamics, more fuel-efficient engines and the introduction of light-alloy drop tanks, the Bf 109F offered a much increased maximum range of 1,700 km (1,060 mi)^{[68][verification needed]} compared to the Bf 109E's maximum range of 660 km (410 mi).

The canopy stayed essentially the same as that of the E-4 although the handbook for the 'F' stipulated that the forward, lower triangular panel to starboard was to be replaced by a metal panel with a port for firing signal flares. Many F-1s and F-2s kept this section glazed. A two-piece, all-metal armour plate head shield was added, as on the E-4, to the hinged portion of the canopy, although some lacked the curved top section. A bullet-resistant windscreen could be fitted as an option.^[69] The fuel tank was self-sealing, and around 1942 Bf 109Fs were retrofitted with additional armour made from layered light-alloy plate just aft of the pilot and fuel tank. The fuselage aft of the canopy remained essentially unchanged in its externals.

The tail section of the aircraft was redesigned as well. The rudder was slightly reduced in area and the symmetrical fin section changed to an airfoil shape, producing a sideways lift force that swung the tail slightly to the left. This helped increase the effectiveness of the rudder, and reduced the need for application of right rudder on takeoff to counteract torque effects from the engine and propeller. The conspicuous bracing struts were removed from the horizontal tailplanes which were relocated to slightly below and forward of their original positions. A semi-retractable tailwheel was fitted and the main undercarriage legs were raked forward by six degrees to improve the ground handling. An unexpected structural flaw of the wing and tail section was revealed as the first Bf 109Fs were rushed into service; some aircraft crashed or nearly crashed, with either the wing surface wrinkling or fracturing, or by the tail structure failing. In one such accident, the commander of JG 2 "Richthofen", Wilhelm Balthasar lost his life when he was attacked by a Spitfire during a test flight. While making an evasive manoeuvre, the wings broke away and Balthasar was killed when his aircraft hit the ground. Slightly thicker wing skins and reinforced spars dealt with the wing problems. Tests were also carried out to find out why the tails had failed, and it was found that at certain engine settings a high-frequency oscillation in the tailplane spar was overlapped by harmonic vibrations from the engine; the combined effect being enough to cause structural failure at the rear fuselage/fin attachment point. Initially two external stiffening plates were screwed onto the outer fuselage on each side, and later the entire structure was reinforced.^[66]

The entire wing was redesigned, the most obvious change being the new quasi-elliptical wingtips, and the slight reduction of the aerodynamic area to 16.05 m² (172.76 ft²). Other features of the redesigned wings included new leading edge slats, which were slightly shorter but had a slightly increased chord; and new rounded, removable wingtips which changed the planview of the wings and increased the span slightly over that of the E-series. Frise-type ailerons replaced the plain ailerons of the previous models. The 2R₁ profile was used with a thickness-to-chord ratio of 14.2% at the root reducing to 11.35% at the last rib. As before, dihedral was 6° 32'.^[67]

The wing radiators were shallower and set farther back on the wing. A new cooling system was introduced which was automatically regulated by a thermostat with interconnected variable position inlet and outlet flaps that would balance the lowest drag possible with the most efficient cooling. A new radiator, shallower but wider than that fitted to the E was developed. A boundary layer duct allowed continual airflow to pass through the airfoil above the radiator ducting and exit from the trailing edge of the upper split flap. The lower split flap was mechanically linked to the central "main" flap, while the upper split flap and forward bath lip position were regulated via a thermostatic valve which automatically positioned the flaps for maximum cooling effectiveness.^[70] In 1941 "cutoff" valves were introduced which allowed the pilot to shut down either wing radiator in the event of one being damaged; this allowed the remaining coolant to be preserved and the damaged aircraft returned to base. However, these valves were delivered to frontline units as kits, the number of which, for unknown reasons, was limited.^[71] These cutoff valves were later factory standard fitting for Bf 109G-^[72] and K-series.^[73][74]

[edit] Armament

The armament of the Bf 109F was revised and now consisted of the two synchronized 7.92 mm (.312 in) MG 17s with 500 rpg above the engine plus a Motorkanone cannon firing through the propeller hub. The pilot's opinion on the new armament was mixed: Oberst Adolf Galland criticised the light armament as inadequate for the average pilot, while Major Walter Oesau preferred to fly a Bf 109E, and Oberst Werner Mölders saw the single centreline gun as an improvement.

With the early tail unit problems out of the way, pilots generally agreed that the F series was the best-handling of all the Bf 109 series.^[75] Mölders flew one of the first operational Bf 109F-1s over England from early October 1940; he may well have been credited with shooting down eight Hurricanes and four Spitfires while flying W.No 5628, Stammkennzeichen SG+GW between 11 October and 29 October 1940.^[63][76]

[edit] Bf 109F variants and sub-variants

[edit] F-0, F-1, F-2

As the DB601E was not yet available in numbers, the pre-production F-0 (the only F variant to have a rectangular supercharger intake) and the first production series F-1/F-2 received the 1,175 PS (1,159 hp, 864 kW) DB 601N engine driving a VDM 9-11207 propeller.^[67] The F-0/F-1 and F-2 only differed in their armament; the F-1 being fitted with one 20 mm MG FF/M Motorkanone firing through the engine hub, with 60 rounds. The F-1 first saw action in the Battle of Britain in October 1940 with JG 51.^[77] A total of 208 F-1s were built between August 1940 and February 1941 by Messerschmitt Regensburg and the Wiener Neustädter Flugzeugwerke.^[78]

The F-2 introduced the 15 mm Mauser MG 151 cannon with 200 rounds.^[79] The Motorkanone was supplemented by two synchronized 7.92 mm (.312 in) MG 17 machine guns mounted under the engine cowl, with 500 rpg. As the harder-hitting 20 mm version of the same gun become available, a number of F-2s were retrofitted with it in the field. About 1,380 F-2s were built between October 1940 and August 1941 by AGO, Arado, Erla, Messerschmitt Regensburg and WNF.^[78] No tropicalized version was built, although individual F-2s were retrofitted with sand filters in the field.^[80] The maximum speed of the F-1 and F-2 was 615 km/h (382 mph) at rated altitude.

• F-0 (Pre-production aircraft built from E series airframes, Adolf Galland was one of the few to fly one operationally)
• F-1 (Armed with 1 × 20 mm MG FF/M Motorkanone cannon and 2 × 7.92 mm/.312 in MG 17 machine guns)
• F-2 (Armed with 1 × 15 mm (.59 in) MG 151 cannon and 2 × 7.92 mm/.312 in MG 17)
  • F-2 trop (tropicalized version, only as field conversion)

[edit] F-3, F-4, F-5, F-6

Messerschmitt Bf 109F-4 in the Canada Aviation Museum

The 1,350 PS (1,332 hp, 993 kW) DB 601E was used in the F-3 and F-4 model together with a VDM 9-12010 propeller with broader blades for improved altitude performance.^[66][81] The DB 601 E was initially restricted to 1,200 PS (1,184 hp, 883 kW) at 2,500 rpm;^[81] however, the full rating of 1,350 PS at 2,500 rpm was cleared for service use by February 1942. The DB 601 E was able to use 87 octane "B-4" aviation fuel, despite its increased performance; while the earlier DB 601N ran on 100 octane designated as "C-3" by the Luftwaffe.^[82]

Only 15 examples of the F-3 are believed to have been produced by Messerschmitt Regesnburg between October 1940 and January 1941. Like the F-1, the F-3 was armed with the 20 mm MG-FF/M and two 7.92 mm (.312 in) MG 17s.^[83]

From the F-4 onward, the new 20 mm Mauser MG 151/20 with 200 rounds was used as the motorkanone.^[79] The first F-4s reached frontline units in June 1941. Production lasted exactly a year between May 1941 and May 1942, with 1,841 of all F-4 variants produced.^[84] Some of the later models were capable of mounting two 20 mm MG 151/20 cannons under the wing in faired gondolas with 135 rpg. These were designated F-4/R1 and 240 of them were produced by W.N.F. in the first quarter of 1942.^[85] This optional additional armament was standardized as field kit for later G and K series. A special high-altitude variant, the F-4/Z featuring GM-1 boost, was also built with a production run of 544 in the first quarter of 1942 and saw extensive use.^[82][86] Finally, the Erla factory produced 576 tropicalized F-4 trop in the first half of 1942.^[82]

With its initial engine rating of 1,200 PS, the maximum speed of the F-4 (and F-3) was 635 km/h^[87] (394 mph) at rated altitude; and with the clearance of the full rating of 1,350 PS, maximum speed increased to 670 km/h (420 mph).^[88][89]

• F-3 (As F-1 but with 1350 PS DB 601E engine, produced in limited numbers)
• F-4 (As F-2 but with DB 601E engine, 20 mm MG 151/20 "Motorkanone" cannon replacing the 15 mm MG 151)
  • F-4/R1 (As F-4, but capable of mounting two 20 mm MG 151/20 cannons in underwing gondolas)
  • F-4/Z (As F-4, high-altitude fighter with GM-1 boost)
• F-5 (Recon version of F-4, only two 7.92 mm/.312 in MG 17)
• F-6 (Recon version of F-4, improved camera equipment)

[edit] Bf 109G "Gustav"

Bf 109G-2/Trop "Black 6", Now on static display RAF Hendon London

[edit] Introduction

The Bf 109 G-series was developed from the largely identical F-series airframe, although there were detail differences. Modifications included reinforced wing structure, an internal bullet-proof windscreen, the use of heavier, welded framing for the cockpit transparencies, and additional light-alloy armour for the fuel tank. It was originally intended that the wheel wells would incorporate small doors to cover the outer portion of the wheels when retracted. To incorporate these the outer wheel bays were squared off. Two small inlet scoops for additional cooling of the spark plugs were added on both sides of the forward engine cowlings. A less obvious difference was the omission of the boundary layer bypass outlets, which had been a feature of the F-series, on the upper radiator flaps.^[90][91]

Like most German aircraft produced in World War II, the Bf 109 G-series was designed to adapt to different operational tasks with greater versatility; larger modifications to fulfil a specific mission task like long-range recon or long-range fighter-bomber were with "Rüststand" and given a "/R" suffix, smaller modifications on the production line or during overhaul like equipment changes were made with kits of pre-packaged parts known as Umrüst-Bausätze, usually contracted to Umbau and given a "/U" suffix. Field kits known as Rüstsätze were also available but those did not change the aircraft designation. Special high-altitude interceptors with GM-1 nitrous oxide injection high-altitude boost and pressurized cockpits were also produced.

The newly fitted Daimler-Benz DB 605A engine was a development of the DB 601E engine utilised by the preceding Bf 109F-4; displacement and compression ratio were increased as well as other detail improvements. Takeoff and emergency power of 1,475 PS (1,455 hp, 1,085 kW) was achieved with 1.42 atm of boost at 2,800 rpm. The DB605 suffered from reliability problems during the first year of operation, and this output was initially banned by VT-Anw.Nr.2206, forcing Luftwaffe units to limit maximum power output to 1,310 PS (1,292 hp, 964 kW) at 2,600 rpm and 1.3 atm manifold pressure. The full output was not reinstated until 8 June 1943 when Daimler-Benz issued a technical directive.^[92] Up to 1944, the G-series was powered by the 1,475 PS Daimler-Benz DB 605 driving a three-blade VDM 9-12087A variable-pitch propeller with a diameter of 3 m (9.8 ft) with even broader blades than used on the F-series. Pitch control, as on the 109F, was either "electro-mechanical"" (automatic) or "manual-electric" using a thumb-switch on the throttle lever.^[92] From 1944 a new high-altitude propeller with broader blades was introduced, designated VDM 9-12159, and was fitted to high-altitude variants with the DB 605AS or D-series engines.

The early versions of the Bf 109G closely resembled the Bf 109 F-4 and carried the same basic armament; however, as the basic airframe was modified to keep pace with different operational requirements, the basically clean design began to change. From the spring of 1943, the G-series saw the appearance of bulges in the cowling when the 7.92 mm (.312 in) MG 17 were replaced with 13 mm (.51 in) MG 131 machine guns (G-5 onwards) due to the latter's much larger breechblock, and on the wings (due to larger tyres), leading to the Bf 109 G-6's nickname "Die Beule" ("The Bulge"). The Bf 109G continued to be improved: new clear-view cockpits, greater firepower in the form of the 30 mm (1.18 in) MK 108 cannon were introduced in late 1943; and a new, enlarged supercharger for the DB605, a larger vertical stabilizer (G-5 onwards), and MW 50 power boost in 1944.

Erich Hartmann, the World's top scoring fighter ace, claiming 352 victories, flew only the Bf 109G, of which he said:

It was very manoeuverable, and it was easy to handle. It speeded up very fast, if you dived a little. And in the acrobatics manoeuver, you could spin with the 109, and go very easy out of the spin. The only problems occurred during takeoff. It had a strong engine, and a small, narrow-tread undercarriage. If you took off too fast it would turn [roll] ninety degrees away. We lost a lot of pilots in takeoffs.^[93]

From the Bf 109 G-5 on an enlarged wooden tail unit (identifiable by a taller vertical stabilizer and rudder with a morticed balance tab, rather than the angled shape) was often fitted. This tail unit was standardised on G-10s and K-4s. Although the enlarged tail unit improved handling, especially on the ground, it weighed more than the standard metal tail unit and required that a counterweight was fitted in the nose, increasing the variant's overall weight.^[94]

With the Bf 109G, a number of special versions were introduced to cope with special mission profiles. Here, long-range fighter-reconnaissance and high-altitude interceptors can be mentioned. The former were capable of carrying two 300 L (80 US gal) drop tanks, one under each wing; and the latter received pressurized cockpits for pilot comfort and GM-1 nitrous oxide "boost" for high altitudes. The latter system, when engaged, was capable of increasing engine output by 223 kW (300 hp) above the rated altitude to increase high-altitude performance.

[edit] Early Bf 109G models

Gustav Rödel Bf 109 G-2 remake in the Luftwaffenmuseum in Berlin

[edit] G-1, G-2

The G-1, produced from February 1942, was the first of the G-series. This was the first production Bf 109 with a pressurized cockpit and could be identified by the small, horn-shaped air intake for the cockpit compressor just above the supercharger intake, on the left upper cowling. In addition, the angled armour plate for the pilot's head was replaced by a vertical piece which sealed-off the rear of the side-hinged cockpit canopy. Small, triangular armour-glass panels were fitted into the upper corners of this armour, although there were aircraft in which the plate was solid steel. Silica gel capsules were placed in each pane of the windscreen and opening canopy to absorb any moisture which may have been trapped in the double glazing. The last 80 G-1s built were lightweight G-1/R2. In these GM-1 nitrous oxide 'boost' was used, and the pilot's back armour was removed, as were all fittings for the long-range drop tank. A few G-1 flown by I./JG 1 are known to have carried the underwing 20 mm MG 151/20 cannon gondolas.^[95]

The G-2, which started production in May 1942, lacked the cabin pressurization and GM-1 installation.^[96] Performance-wise it was identical to the G-1. The canopy reverted to one layer of glazing and incorporated the angled head armour used on the F-4, although several G-2 had the vertical type as fitted to the G-1. Several Rüstsätze could be fitted, although installing these did not change the designation of the aircraft. Instead the "/R" suffix referred to the G-2's Rüstzustand or equipment condition of the airframe, which was assigned at the factory rather than in the field. There were two Rüstzustand planned for G-2s:

• G-2/R1: had one 300 L (80 US gal) drop tank beneath each wing, plus an ETC bomb rack under the fuselage, capable of carrying a 500 kg (1,100 lb) bomb and an auxiliary undercarriage unit beneath the fuselage. Also could carry a large jettisonable tail wheel, just aft of the cockpit.^[96]
• G-2/R2: a reconnaissance aircraft with GM-1 and camera equipment.

The rack and internal fuel lines for carrying a 300 L (80 US gal) drop-tank were widely used on G-2s, as were the underwing 20 mm MG 151/20 cannon gondolas. Several G-2s were fitted with the ETC 500 bomb rack, capable of carrying one 250 kg (550 lb) bomb. The final G-2 production batches built by Erla and Messerschmitt Regensburg were equipped as tropical aircraft (often referred to as G-2 trop), equipped with a sand-filter on the front of the supercharger intake and two small, teardrop-shaped metal brackets on the left side of the fuselage, below the cockpit sill. These were used as mounts for specially designed sun umbrellas (called Sonderwerkzeug or Special tool), which were used to shade the cockpit.^[97]

A total of 167 G-1s were built between February and June 1942,^[98] 1,586 G-2s between May 1942 and February 1943, and one further G-2 was built in Győr, Hungary, in 1943.^[99] Maximum speed of the G-2 was 537 km/h (334 mph) at sea level and 660 km/h (410 mph) at 7,000 m (22,970 ft) rated altitude with the initial reduced 1.3 atm rating. Performance of the G-1 was similar, but above rated altitude the GM-1 system it was equipped with could be used to provide an additional 350 horsepower.^[100] With his G-1/R2, pilot R. Klein achieved 660 km/h (420 mph) at 12,000 m (39,370 ft), and a ceiling of 13,800 m (45,275 ft).^[100]

The following variants of the G-1 and G-2 were produced:

• G-0 (Pre-production aircraft, powered by a DB 601E engine)
• G-1 (Pressurized fighter, powered by a Db 605A engine)
  • G-1/R2 (Reconnaissance fighter)
  • G-1/U2 (High-altitude fighter with GM-1)
• G-2 (Light fighter)
  • G-2/R1 (Long-range Fighter-bomber or JaboRei, with 2 × 300 L/80 US gal underwing drop tanks, one 500 kg/1,100 lb bomb under fuselage, extended second tail wheel for large bombs, only prototype)
  • G-2/R2 (Reconnaissance fighter)
  • G-2 trop (Tropicalized fighter)

[edit] G-3, G-4

In September 1942, the G-4 appeared; this version was identical to the G-2 in all respects, including performance, except for being fitted with the FuG 16 VHF radio set, which provided much clearer radio transmissions and had three-times the range of the earlier HF sets. Externally this could be recognised by the position of the fuselage antenna lead-in which was moved further aft to between frames seven and eight on the fuselage spine.^[101] Due to the steady weight increases of the 109, from the spring of 1943 larger 660 x 160 mm (26 x 6.3 in) mainwheels were introduced, replacing the previously used 650 x 150 mm (25.6 x 6 in) type. The undercarriage legs were altered so that the wheel's vertical axis was nearly upright rather than being parallel with the oleo leg. These changes resulted in the fitting of teardrop-shaped fairings to the upper wing surface above the wheel-wells to accommodate the upper part of the mainwheels. The larger wheels and fairings were often retrofitted to G-2s.^{[Notes 9]} In addition, a larger 350 x 135 mm (14 x 5 in) tailwheel replaced the original 290 x 110 mm (11 x 4 in) one; the larger tailwheel no longer fitted the recess, so the retraction mechanism was disconnected and the tailwheel fixed down.^[102] Up to July 1943, 1,242 G-4s were produced, with an additional four in Győr and WNF factories in the second half of 1943.^[103] Between January and February 1943, 50 examples of a pressurized version, the G-3 were also produced; similar to the G-1 although it was equipped with the same FuG 16 VHF radio set as the G-4.^[104]

The following variants of the G-3 and G-4 were produced:

• G-3 (Pressurized fighter, as G-1 with FuG 16 VHF radio; 50 built)
• G-4 (Fighter)
  • G-4/R2 (Reconnaissance fighter)
  • G-4/R3 (Long-range reconnaissance fighter, with 2 × 300 L/80 US gal underwing droptanks)
  • G-4 trop (Tropicalized fighter)
  • G-4/U3 (Reconnaissance fighter)
  • G-4y (Command fighter)

[edit] G-5, G-6

In February 1943, the G-6 was introduced with the 13 mm (.51 in) MG 131s, replacing the smaller 7.92 mm (.312 in) MG 17 – externally this resulted in two sizeable blisters over the guns, reducing speed by 9 km/h (6 mph). Over 12,000 examples were built well into 1944 although contradictory factory and RLM records do not allow an exact tally.^[105] The G-5 with a pressurized cockpit was identical to the G-6. A total of 475 examples were built between May 1943 and August 1944.^[106] The G-5/AS was equipped with a DB 605AS engine for high-altitude missions. GM-1-boosted G-5 and G-6 variants received the additional designation of "/U2".^[107] and were clearly identifyable as they use a modified, aerodynamically cleaner, engine cowl without the usual blisters.

Bf 109G-6 on display in the Polish Aviation Museum in Kraków

The G-6/U4 variant was armed with a 30 mm (1.18 in) MK 108 cannon mounted as a Motorkanone firing through the propeller hub instead of the 20 mm MG 151/20.^[108] The G-6 was very often seen during 1943 fitted with assembly sets, used to carry bombs or a drop tank, for use as a night fighter, or to increase firepower by adding rockets or extra gondola guns.

The following variants of the G-5 and G-6 were produced:

• G-5 (Pressurized fighter)
  • G-5/U2 (High-altitude fighter with GM-1 boost)
  • G-5/U2/R2 (High-altitude reconnaissance fighter with GM-1 boost)
  • G-5/AS (High-altitude fighter with DB 605AS engine)
  • G-5y (Command fighter)
• G-6 (Light fighter)
  • G-6/R2 (Reconnaissance fighter, with MW 50)
  • G-6/R3 (Long-range reconnaissance fighter, with 2 × 300 L/80 US gal underwing droptanks)
  • G-6 trop (Tropicalized fighter)
  • G-6/U2 (Fitted with GM-1)
  • G-6/U3 ((Reconnaissance fighter)
  • G-6/U4 (As G-6 but with 30 mm/1.18 in MK 108 Motorkanone engine cannon)
  • G-6y (Command fighter)
  • G-6/AS (High-altitude fighter with DB 605AS engine)
  • G-6/ASy (High-altitude command fighter)
  • G-6N (Night fighter, usually with Rüstsatz VI (two underwing MG 151/20 cannons) and sometimes with FuG 350Z Naxos)
  • G-6/U4 N (as G-6N but with 30 mm/1.18 in MK 108 Motorkanone engine cannon)

One offensive weapons upgrade for the Bf 109G that was once thought to have been associated with the /R2 designation, in postwar books on the Luftwaffe, was one that mounted the Werfer-Granate 21 rocket weapon system with one launching tube under each wing panel. Intended as a "stand-off" weapon to be employed against Allied bomber formations, the Wfr. Gr. 21 rocket fitment never received an official Rüstsatz designation but was inofficially known as the BR21.^{[citation needed]}

[edit] Late Bf 109G models

[edit] Improvements to the design

During the course of 1943, a number of improvements were gradually introduced. In an attempt to increase the pilot's field of view an armoured glass head-rest, the so-called Galland Panzer was developed, and subsequently began replacing the bulky armour plate in the spring of 1943. Towards the end of the year the clear-view Erla Haube canopy appeared, named after one of the sub-contractors involved in building the Bf 109. Often mis-named the "Galland Hood" in postwar Western aviation books and periodicals, it eventually replaced the older heavily framed two-piece canopy on the Bf 109G. The canopy structure was completely redesigned to incorporate a greater area of clear perspex; the welded framing was reduced to a minimum and there was no longer a fixed rear portion, with the entire structure aft of the windscreen being hinged to swing to starboard when opened.^[109]

The Bf 109 G-10, AS-engined G-5s, G-6s and G-14s as well as the K-4 saw a refinement of the engine cowlings. The blisters which had formally covered the spent shell-casing chutes of the MG 131s became more streamlined and were lengthened and enlarged to cover both the weapons and the engine bearers. Initial prototype versions were symmetrical, but as larger superchargers were fitted, the engines required modified upper engine bearers to clear the supercharger housing, and as a result the final shape of the new cowling was asymmetrical, being enlarged on the port size where the supercharger was mounted on the DB engine. There were also special streamlined panels fitted to the forward fuselage. These so-called agglomerations could be seen in several different patterns. Because of their aerodynamically more efficient form in a side-view of DB 605AS and D -powered Bf 109 Gs and Ks, the agglomerations were barely discernible compared with the conspicuous fairings they replaced.^[110]

[edit] Late-production G-6, G-14, G-14/AS

Some versions of the G-6 and later Gs had a taller tail unit and redesigned rudder which improved stability at high speeds. The introduction of the WGr. 21 cm (8 in) under-wing mortar/rockets and the 30 mm (1.18 in) MK 108 cannon increased firepower. Certain production batches of the Bf 109G were fitted with aileron Flettner tabs to decrease stick forces at high speeds. A radio-navigational method, the Y-Verführung (Y-Guidance) was introduced with the FuG 16ZY.^[111]

Subsequent Bf 109G versions were essentially modified versions of the basic G-6 airframe. Early in 1944, new engines with larger superchargers for improved high-altitude performance (DB 605AS), or with MW-50 water injection for improved low/medium-altitude performance (DB 605AM), or these two features combined (DB 605ASM) were introduced into the Bf 109 G-6. Maximum speed of the G-5/G-6 was 530 km/h (320 mph) at sea level, 640 km/h (391 mph) at 6,600 m (21,650 ft)-rated altitude at 1.42 atm boost.

The G-14 arrived in July 1944 at the invasion front over France.^[112] It represented an attempt to create a standard type, incorporating many changes which had been introduced during production of the G-6, and which led to a plethora of variants, plaguing decentralized mass production.^[112] The standardization attempt proved to be a failure,^[112] but overall the type offered improved combat performance, as MW 50 power boosting water injection (increasing output to 1,800 PS (1,775 hp, 1,324 kW), the clear-view Erla Haube was now standard installation.^[113] Top speed was 568 km/h (353 mph) at sea level, and 665 km/h (413 mph) at 5 km (16,400 ft) altitude. A high-altitude fighter, designated G-14/AS was also produced with the DB 605ASM high-altitude engine. The ASM engine was built with a larger capacity supercharger, and had a higher rated altitude, and correspondingly the top speed of the G-14/AS was 560 km/h (348 mph) at sea level, and 680 km/h (422 mph) at 5 km (26,600 ft) altitude.

There was increasing tendency to use plywood on some less vital parts e.g. on a taller tailfin/rudder unit, pilot seat or instrument panel. A caution estimate based on the available records suggest that about 5,500 G-14s and G-14/AS were built.^[114]

The following variants of the G-14 were produced:

• G-14 (Fighter; standardized late-production G-6; DB 605AM engine, MW 50 boost)
  • G-14/AS (High-altitude fighter with DB 605ASM engine, MW 50 boost)
  • G-14/ASy (High-altitude command fighter)
  • G-14y (command fighter)
  • G-14/U4 (As G-14, but with 30 mm/1.18 in MK 108 Motorkanone engine cannon)

[edit] G-10

Bf 109G-10, with Erla Haube canopy and taller, wooden vertical fin/rudder

Referred to as the "bastard aircraft of the Erla factory" in the Luftwaffe's Aircraft Variants Book of December 1944,^[115] the G-10 was a Bf 109 G airframe combined with the new DB 605 D-2 engine,^{[Notes 10]} created to maintain production levels with minimal disruption of the assembly lines until production of K-series airframes would reach sufficient levels. Despite what the designation would suggest, it appeared in service after the G-14 in November 1944, largely replacing previous G-series aircraft on the production lines of Erla, WNF and Messerschmitt Regensburg factories. Evidence suggests that G-10s were rebuilt from older airframes, supplementing production of the new K-4s with aircraft of almost equal value in the cheapest possible manner. One apparent indication was two aircraft identification plates on the port forward fuselage, below the windscreen rather than one.^[117]

The most recognizable external change was the use of the "Erla-Haube" clear-view canopy. Internal changes included inheriting the new 2,000 W generator and the DB 605 D-2 engine of the 109K. Apart from the standardised streamlined engine cowlings, G-10s with the DB605 D-2 were equipped as standard with the MW-50 booster system (DB 605DM) and had a larger Fo 987 oil cooler housed in a deeper fairing. Also, because of the engine's enlarged crankcase and the oil return lines which ran in front of it, these G-10s had small blister fairings incorporated into the lower engine cowlings, forward of and below the exhaust stacks.^[118]

The following variants of the G-10 were produced:

• G-10 (Light fighter with DB605DM or DB/DC engine)
  • G-10/R2 (Bad-weather fighter with PKS 12 autopilot)
  • G-10/R5 (Reconnaissance fighter)
  • G-10/R6 (Bad-weather fighter)
  • G-10/U4 (As G-10 but with 30 mm/1.18 in MK 108 Motorkanone engine cannon)

Approximately 2,600 G-10s were produced from October 1944 until the war's end.

[edit] Miscellaneous variants: G-8, G-12

The G-8 was a dedicated reconnaissance version based on the G-6. The G-8 often had only the Motorkanone engine cannon or the cowling machine guns installed, and there were several subversions for short- or long-range reconnaissance missions with a wide variety of cameras and radios available for use.^[119]

The Bf 109 G-12 was a two-seat trainer version of the Bf 109. This was a conversion of "war-weary" or rebuilt G-4 and G-6 airframes;^[115][120] the space needed for the second cockpit was gained by reducing the internal fuel capacity to only 240 L (60 US gal) meaning that the 300 L (80 US gal) drop tank was employed as standard equipment. This version was rarely armed with anything more than one or two cowling machine guns.^[121] The rear cockpit canopy was bowed out to give the instructor, who sat behind the student pilot in an armoured seat, a clearer view. The rear cockpit was also equipped with a basic instrument panel and all flight controls.^[122]

Bf 109G subtypes and variants

The base subtypes could be equipped with Rüstsatz add-on standard field kits; in practice this meant hanging on some sort of additional equipment like droptanks, bombs or cannons to standard attachment points, present on all production aircraft. Aircraft could be modified in the factory with Umrüst-bausatz (Umbau) conversion kits or by adding extra equipment, designated as Rüstzustand, to convert standard airframes for special roles – a reconnaissance- or bad-weather fighter, for example. Unlike the Rüstsatz field-kits, these modifications were permanent.

The Rüstsatz kits were designated by the letter "R" and a Roman numeral. Rüstsatz kits did not alter the aircraft's designation, so a Bf 109 G-6 with Rüstsatz II (50 kg/110 lb bombs) remained designated as 'Bf 109 G-6', and not 'G-6/R2' – the G-6/R2 was a reconnaissance fighter with MW 50, as suggested by most publications. The Umrüst-Bausatz, Umbau, or Rüstzustand were identified with either an "/R" or "/U" suffix and an Arabic number, e.g. Bf 109 G-10/U4.

Common Rüstsatz kits: Bf 109G:^[123]

• R I (ETC 501/IX b bomb rack under the fuselage, fusing equipment for an SC 250 or SD 250 type 250 kg (550 lb) bomb)
• R II (ETC 50/VIII d bomb rack under the fuselage, fusing equipment, for four SC 50 type 50 kg (110 lb) bombs)
• R III (Schloß 503A-1 rack for one fuselage drop tank (300 L/80 US gal))
• R IV (two 30 mm (1.18 in) Rheinmetall-Borsig MK 108 underwing gunpods)
• R VI (two 20 mm Mauser MG 151/20 underwing gunpods with 135 rpg)
• R VII (Peilrufanlage)

Common Umrüst-Bausatz (Umbau) numbers:

• U1 (Messerschmitt P6 reversible-pitch propeller to be used as air brake, only prototypes)
• U2 (GM-1 boost, during 1944 several hundred converted to MW-50 boost)
• U3 (Reconnaissance conversion, in autumn 1943 G-6/U3 adopted as G-8 production variant)
• U4 (30 mm (1.18 in) MK 108 Motorkanone engine-mounted cannon)

[edit] Bf 109H

Messerschmitt Bf 109H-1

The Bf 109H was intended to be a high-altitude fighter, developed from the F-series. The wingspan was increased through the addition of new, constant-chord inner wing panels to 11.92 m (39.11 ft), and the widened stabilizer again received a supporting strut leading from the fuselage. Maximum speed was 750 km/h (470 mph) at 10,100 m (33,140 ft). A small number of Bf 109 H-1s were built, flying several sorties over Britain and France. Bf 109 H-2 and H-5 developments were also planned, but the entire H-series was scrapped because of wing flutter problems.^[124]

• H-0 (Pre-production aircraft, rebuilt from F-4/Z, powered by a DB 601E engine with GM-1 boost)
• H-1 (Production version, based on G-5 airframes, powered by a DB 605A engine with GM-1 boost)

[edit] Bf 109K "Kurfürst"

Messerschmitt Bf 109 K-4

[edit] K-4

The Bf 109K was the last of the series to see operational duty and the last in the Bf 109 evolutionary line. The K series was a response to the bewildering array of series, models, modification kits and factory conversions for the Bf 109, which made production and maintenance complicated and costly — something Germany could ill-afford late in the war. The RLM ordered Messerschmitt to rationalise production of the Bf 109, consolidating parts, types, and so on, to produce a uniform, standard model with better interchangeability of parts and equipment. At the same time, the existing flaws of the design were to be remedied. Work on the new version began in the spring of 1943, and the prototype was ready by the autumn of that year. Series production started in August 1944 with the K-4 model, due to changes in the design and delays with the new DB 605D powerplant. The K-4 was the only version to be mass produced.^[125]

Externally the K series could be identified by changes in the locations of the radio equipment hatch,^{[Notes 11]} which was moved forward and to a higher position between frames four and five, and the filler point for the fuselage fuel tank, which was moved forward to a location between frames two and three. In addition, the D/F loop was moved aft to sit between frames three and four on the top fuselage spine and a small circular plate above the footstep on the port side of the fuselage was deleted. The rudder was fitted as standard with a Flettner tab and two fixed tabs although some rare examples were not fitted with the fixed tabs. All K-4s were to be fitted with a long retractable tailwheel (350 x 135 mm/14 x 5 in) with two small clamshell doors covering the recess when the tail-wheel was retracted.

The wings featured the large rectangular fairings for the large 660 x 190 mm (26 x 7 in) main wheels. Small wheel well doors, originally planned for the G series, were fitted to the outer ends of the wheel bays, covering the outer wheels when retracted. These doors were often removed by front-line units. The ailerons were fitted with small, adjustable trim tabs. The radio equipment was the FuG 16ZY with an antenna mast fitted under the port outer wing and FuG 25a IFF as well as the FuG 125 Hermine D/F equipment. Internally, the oxygen bottles were relocated from the rear fuselage to the right wing.^[126] Flettner tabs for the ailerons were also to be fitted to serial production aircraft to reduce control forces, but are only seen on photos of later production aircraft.

Armament of the K-4 consisted of a 30 mm (1.18 in) MK 108 engine-mounted cannon (Motorkanone) with 65 rounds, and two 13 mm (.51 in) MG 131s in the nose with 300 rpg although some K-4s were fitted with the MG 151/20 as the Motorkanone.^[127] Additional Rüstsätze, or equipment kits, such as a 300 L (80 US gal) drop tank (R III), bombs up to the size of 500 kg/1,100 lb (R I), underwing 20 mm Mauser MG 151/20 cannon gondola pods (R IV) or 21 cm (8 in) Wfr.Gr. 21 rockets (as on the Gustav models) could be carried after minimal preparations; the latter two however were rarely used by Bf 109 units at this stage of the war, but there is evidence that III./JG 26 were almost completely equipped with K-4s which were fitted with R IV. In addition there were problems with the 30 mm (1.18 in) MK 108 Motorkanone:

The 30mm cannon were extremely potent weapons, but they had a tendency to jam, and apparently all of the K-4s supplied to III./JG 26 were also equipped with 20mm-guns in the hated underwing tubs. Uffz. Georg Genth's regular aircraft was a G-10, but on occasion he flew a K-4. He preferred the G-10 as a dogfighter, as the K-4's bulky armament sharply reduced its manouevrability.^[128]

Power was provided by a Daimler-Benz DB 605DM (early models) of 1,800 PS output and later the DB 605DB/DC powerplant with 1,850/2,000 PS output.^[129][130] A wide-chord, three bladed VDM 9-12159 propeller of 3 m diameter^[73] was used, as on the G-6/AS, G-14/AS and G-10.

Deliveries began in mid-October 1944. 534 examples had been delivered by the Messerschmitt A.G., Regensburg by the end of November 1944,^[131] and 856 by the end of the year.^[132] Regensburg delivered a total of 1593 by the end of March 1945, after which production figures are missing. With such a high rate of production, despite continuous heavy fighting, by the end of January 1945 314 K-4s - about every fourth 109 - were listed on hand with the 1st line Luftwaffe units. Ultimately it was intended to equip all Bf 109 units with the 109K, which marked the final stage of 109 development before the jet age.^[133]

The Bf 109 K-4 was the fastest 109 of World War II, reaching 715 km/h (445 mph) at 7,500 m (24,610 ft) altitude; improved propellers were being developed when the war ended which would boost the speed to 727 km/h (452 mph),^[134] and 741 km/h (460 mph) was expected with a swept-back propeller design.^[135] Rate of climb was outstanding 4,820 ft (1,470 m)/min at 1.98 atm^[134]. The standard Revi 16C reflector sight was fitted, which was to be replaced later by the EZ 42 Gyro gunsight.^[136] With such improvements in performance, the Bf 109 remained comparable to opposing fighters until the end of the war. However, the deteriorating ability of the thousands of novice Luftwaffe pilots by this stage of the war meant the 109's strengths were of little value against the numerous and well-trained Allied fighter pilots.

[edit] Other Bf 109K projects and prototypes

Several other versions were projected based on the 109K airframe - K-6, K-8, K-10 and K-14. In the proposed K-6 the armament would have been two 13 mm (.51 in) MG 131 above the engine, along with a 30 mm (1.18 in) MK 108 Motorkanone and an internally-mounted MK 108 in each wing, with 45 rpg. Alternatively, the wing MK 108s could be substituted by 20 mm MG 151/20s, with 100 rpg. Armour weight was increased to 200 lb (91 kg). Takeoff weight was 7,986 lb (3,622 kg). Some K-6 prototypes were built and tested at the Tarnewitz weapons-testing centre.

Project drawings of the K-10 show an K-series airframe powered by the two-stage DB 605L high altitude engine, a high-velocity 30 mm (1.18 in) MK 103M Motorkanone, and two 30 mm (1.18 in) MK 108 cannons in the wings; the cowl 13 mm (.51 in) MG 131s were dispensed with.^{[citation needed]}

Some sources point to limited use of the K-14, intended as high-altitude heavy fighter. Two airframes are listed as delivered to II./JG52 under Major Wilhelm Batz in late spring of 1945, these being armed with only one 30 mm (1.18 in) cannon, but the type's existence cannot be positively confirmed. The K-14 was to be powered by the two-stage supercharged DB 605L engine, with a rumoured use of a four bladed propeller, 460 mph (740 km/h) and an operational altitude of 38,000 ft (12,000 m) was projected. Armour and armament were otherwise similar to the K-6.^{[citation needed]}

Common Rüstsatz kits, Bf 109K^[137]

• R I ETC 501/IX b or Schloß 503belly bomb rack, fusing equipment for fitting a 250 kg (550 lb) or 500 kg (1,100 lb) bomb
• R III Schloß 503A-1 rack for one fuselage drop tank (300 L/80 US gal).
• R IV two 20 mm Mauser MG 151/20 underwing gunpods with 135 rpg.
• R VI BSK 16 gun-camera in the left wing between nose ribs 3 and 4.

Known variants

• K-0 Pre-production aircraft, powered by a DB 605DM engine
• K-2 proposed version without pressurized cockpit
• K-4 only serial production version without pressurized cockpit, powered by a DB 605DM, DB or DC engine
• K-6 proposed heavy fighter version, as K-4 with reinforced wings holding two additional 30 mm MK 108 cannons and additional armour
• K-8 proposed reconnaissance version, equipment similar to G-8
• K-10 proposed version, similar to K-6, MK 103M engine cannon instead of MK 108
• K-12 proposed version, dual-seat trainer similar to G-12
• K-14 proposed version, similar to K-6, powered by a DB 605L engine

[edit] Bf 109T "Trägerflugzeug" (carrier aircraft)

Bf 109T-1

Prior to the war the German Navy had become fascinated with the idea of the aircraft carrier. Borrowing ideas from the British and Japanese (mainly Akagi), they started the construction of Graf Zeppelin as part of the rebuilding of the navy. The air group for the carrier was settled on Messerschmitt Bf 109T fighters and Ju 87C dive bombers. The suffix 'T' denotes carrier, 'Träger', in German use.^[138]

Despite references to a Bf 109 T-0 version.^[138] this version never existed. Seven earlier versions (Bf 109 B, Bf 109 C, Bf 109 E) were converted to test carrier equipment. This included, adding a tail-hook, catapult fittings and increasing the wingspan to 11.08 m (36.35 ft). The ailerons were increased in span, as were the slots, and flap travel was increased. The wings were not modified to be folding since the ship Graf Zeppelin was designed around the intended aircraft, so the lifts could accommodate the Bf 109T with its 11 m (36 ft) wingspan. The wings could, however, be detached from the fuselage for transport purposes, as in every version of the Bf 109.^{[139][140][141]}

Following flight tests, especially the catapult tests, 70 T-1 with DB601Ns were to be produced at Fieseler in Kassel, but after seven T-1s were built, the carrier project was canceled. The remaining 63 of 70 T-1s were built as T-2s without carrier equipment and some of the T-1s may have been "upgraded" to T-2 standard. It was found that the performance of the T-2 was closely comparable to the E-4/N and, because of its ability to take off and land in shorter distances, these fighters were assigned to I/JG.77, deployed in Norway on landing strips which were both short and subject to frequent, powerful cross-winds.^[142] At the end of 1941 the unit was ordered to return their aircraft to Germany and received E-3s as replacements.^[143] The armament of the Bf 109T consisted of two 7.92 mm (.312 in) MG 17s above the engine and one 20 mm MG FF/M cannon in each wing.^[138]

Interest in Graf Zeppelin revived when the value of aircraft carriers became obvious, and in 1942 the ship was back in the yards for completion. By this time the Bf 109T was hopelessly outdated and a new fighter would be needed. Messerschmitt responded with the updated Me 155A series, but work on the ship was again canceled and the Me 155 was later re-purposed as a high-altitude interceptor. Design work was transferred to Blohm & Voss and the aircraft was then known as the BV 155. The Bf 109Ts were issued to several training units in 1943. Then, in April 1943 the Jagdstaffel Helgoland was formed^[144] and operated from Düne until late 1943 when the unit transferred to Lister in south Norway. The unit was re-named as 11./JG 11 as of 30 November 1943^[145] and the Bf 109Ts remained in operations until the summer of 1944, after which some were used in training units in Germany.

[edit] Bf 109Z "Zwilling"

Bf 109Z-1

This experimental aircraft was essentially two Bf 109F airframes (together with outer wing panels) joined together by means of a new wing, and new tail section, in a manner paralleled by the F-82 Twin Mustang. In the preproduction model, the right fuselage cockpit was faired over and the pilot flew the aircraft from the left side fuselage. Four variants of this aircraft were proposed, one an interceptor armed with five 30 mm (1.18 in) cannons, and up to a 1,000 kg (2,200 lb) bomb load, the second a fighter bomber version, armed with two MK 108 cannon and up to two 2,200 lb. bombs. Both airframes were to be powered by the DB605 engine. A third and fourth were designed on paper and would be similar to the first two airframes but powered by Jumo 213 engines. Only one Bf 109Z was built, and it was never flown, having been damaged in an Allied bombing raid while in hangar and the project was permanently abandoned in 1944.^[146]

[edit] Developments after World War II

S 199

Hispano Aviacion Ha 1112 Buchon, the second and last Spanish version built by Hispano Aviacion

[edit] Czechoslovak production

After the war, some Bf 109s were produced in Czechoslovakia as the Avia S-99 and Avia S-199. These were modified Bf 109G-14s, the latter with the inferior Junkers Jumo 211F engine, which resulted in an aircraft with remarkably poor handling characteristics and a tendency to crash during landings. As noted above, Czech pilots who had previously flown Spitfires for the RAF nicknamed the aircraft Mezek ("Mule"). They were replaced in frontline service by Soviet jets in 1952, but flew on as trainers for another five years. ^[147]

Several of the S-199s were sold to Israel, forming the basis of the fledgeling Israeli Air Force.^[148]

[edit] Spanish production

In Spain, two versions of the Bf 109G-2, the Hispano Aviacion Ha 1112 "Tripala" and "Buchon",^[149] were built under license, the former with the Hispano-Suiza engine, and the latter with the same Rolls-Royce Merlin engines which had powered Spitfires. Many of these aircraft have been used for theatrical purposes, posing (rather unconvincingly, given their very distinctive undernose air intakes, mandated by the R-R Merlin engines they used) as "Emils" and "Gustavs" in Battle of Britain and Tuskegee Airmen, respectively. These modifications were carried out in the Hispano Aviacion factory in Seville. Germany had agreed to let Spain have 25 un-assembled Bf 109G-2s to help familiarize the Spanish with the Messerschmitt plane. The wings and airframes arrived but not the engines, so the Spanish installed the French Hispano-Suiza engine, and then fitted Rolls-Royce Merlins as late as 1956. A few were still in active service until the late 1960s.^[147] The Ha 1112 was produced until 1958.

[edit] Bf 109 production

Total Bf 109 production was 33,984 units;^[150] wartime production (September 1939 to May 1945) was 30,573 units. Fighter production totalled 47% of all German aircraft production, and the Bf 109 accounted for 57% of all German fighter types produced.^[146] A total of 2,193 Bf 109 A–E were built prewar, from 1936 to August 1939.

Some 865 Bf 109 derivatives were manufactured postwar under licence as Czechoslovakian-built Avia S-99 & S-199s and Spanish-built Hispano Aviación HA-1109 and HA-1112 Buchons.

New production Messerschmitt Bf 109 fighters, 1936–1945.^[151]

Assembly of Bf 109G-6s in a German aircraft factory.

Factory, location	Up to 1939	1939	1940	1941	1942	1943	1944	1945*	Totals*
Messerschmitt, Regensburg				203	486	2,164	6,329	1,241	10,423
Arado, Warnemünde				370					370
Erla, Leipzig				683	875	2,015	4,472	1,018	9,063
Fieseler, Kassel				155					155
W.N.F., Wiener Neustadt				836	1,297	2,200	3,081	541	7,892
Győri Wagon- és Gépgyár, Győr						39	270		309
Ago, Oschersleben				381					381
Totals	1,860	1,540	1,868	2,628	2,658	6,418	14,152	2,800	33,984

• Production up to end of March 1945 only.

[edit] Operational History

Main article: Messerschmitt Bf 109 operational history

The first Bf 109As saw their baptism of fire in the Spanish Civil War. By the September 1939, the Bf 109 became the mainstay fighter of the Luftwaffe by World War II, replacing the biplane fighters, and was instrumental in gaining air superiority for the Wehrmacht during the Blitzkrieg. During the Battle of Britain the type was pressed into new roles as an escort fighter, a role it was not originally designed for, and was widely employed as a fighter-bomber as well as for photo-reconnaissance. Despite mixed results over Britain, with the introduction of the improved Bf 109F into widespread operational service in the spring of 1941, the type proved again to be an effective fighter during the Invasion of Yugoslavia, the Battle of Crete and Operation Barbarossa, the invasion of the USSR and during the Siege of Malta.

In 1942, it begun to be partially replaced by the new German fighter, the FW 190 in Western Europe, but it continued to serve in a multitude of roles on the Eastern Front and in the Defense of the Reich, as well as in the Mediterranean Theatre of Operations Erwin Rommel's Afrikakorps. It was also supplied to several of the Germany's allies, inlcuding Finland, Hungary, Rumania, Bulgaria, Croatia, and Slovakia.

The Bf 109 was credited with more aerial kills than any other aircraft. One hundred and five (possibly 109) Bf 109 pilots were credited with the destruction of 100 or more enemy aircraft. Thirteen of these men scored more than 200 kills, while two scored more than 300. Altogether this group were credited with nearly 15,000 kills between them.^[152] Official ace status was granted to any pilot who scored five or more kills. Applying this to Luftwaffe fighter pilots and their records reveals that "Ace" status belonged to more than 2,500 German pilots.^[153]

Some Bf 109s remained in service for many years after the war. Hungarian 109s were destroyed in Germany by their own crews on 6 May 1945, Romania used its Bf 109s until 1955. The Finnish Air Force did not retire their Bf 109Gs until March 1954. The Spanish Hispanos, however, flew longer. Some were still in service into the late 1960s. They appeared in films (notably The Battle of Britain) playing the role of the Bf 109. Some Hispano airframes were sold to museums which rebuilt them as Bf 109s. The Swiss used their Bf 109Gs well into the 1950s.

[edit] Operators

Bulgaria

• Bulgarian Air Force operated 19 E-3s and 145 G-2/-6/-10s.

Independent State of Croatia

• Zrakoplovstvo Nezavisne Države Hrvatske operated over 50 Bf 109s, including E-4, F-2, G-2/-6/-10 and Ks.

Finland

• Finnish Air Force operated 162 aircraft (48 G-2s, 111 G-6s and three G-8s).

Germany

• Luftwaffe was main operator of the Bf 109.

Hungary

• Royal Hungarian Air Force operated three D-1s, 50 E-3/-4s, 66 F-4s and ~490 G-2/-4/-6/-8/-10/-14s.

Italy

• Regia Aeronautica operated some F-4s and G-6s.

Italian Social Republic

• Aeronautica Nazionale Repubblicana operated 300 G-6/-10/-14s and two G-12s; three K-4s were also received.

Romania

• Royal Romanian Air Force operated 69 E-7s and 135 G-2/-6/-8s.

Czechoslovakia

• Czechoslovakian Air Force - operated captured aircrafts and continued building Messerschmitt Bf 109Gs after the war under the Avia S-99 name, but soon ran out of the 109's Daimler-Benz DB 605 engine after many were destroyed during a explosion at a warehouse in Krásné Březno.

Slovak Republic

• Slovenské vzdušné zbrane operated 16 E-3s, 14 E-7s and 30 G-6s.
• Slovak Insurgent Air Force operated three G-6s.

Spanish State

• Spanish Air Force operated some D-1s, E-3s and 15 F-4s, and may have received several older B-types. Volunteers of Escuadrilla Azul on the Eastern Front operated E-4, E-7, E-7/B, F-2, F-4 (belonged in JG-27 under the command of Luftflotte 2,until April 1943) among G-4 and G-6 (detached in JG-51 under the command Luftflotte 4,until June 1944)

Switzerland

• Swiss Air Force operated ten D-1s, 89 E-3a variants,2 F-4 and 12 G-2s.

Yugoslavia

• Royal Yugoslav Air Force operated 73 E-3a variants.
• SFR Yugoslav Air Force operated several ex-NDH and Bulgarian Bf 109Gs.

Israel

• Israeli Air Force operated a variant bought from Czechoslovakia. Despite the types shortcomings the Israeli scored 8 victories. Egypt and Syria claimed four S-199 kills, and one probable.^[154]

(Wikipedia)