Text: Vladimír Šulc
No other aircraft is more closely associated with the rise and fall of the Luftwaffe during the Second World War than the Messerschmitt Bf 109 fighter. Its early versions became the symbol of German dominance of the skies over Europe in the first half of the war, and its development ensured its competitiveness with newer Allied types. The distinguishing line between the older versions and the later developments was defined by the Bf 109F, nicknamed the ‘Friedrich’, which brought about a slew of changes from the preceding ‘Emil’, first and foremost in the powerplant.
The history of the Bf 109 began to be written at the end of March, 1933, initiated by the Reich Air Ministry’s specification L.A.1432/33, calling for the development of a single-engine fighter monoplane. The competition for contracts included Arado, Heinkel, Focke-Wulf and Bayerische Flugzeugwerke. The latter had, as its technical director, Willy Messerschmitt, whose reputation was greatly enhanced by the success of the recently completed Bf 108 courier aircraft. Messerschmitt’s goal was to design an aircraft with the best possible ratio of performance to weight and size. This would involve the cleanest aerodynamic lines possible. Over the course of the next several months, a number of prototypes were produced, which were mostly used for testing and further development. The end result was a relatively small aircraft with aerodynamically gentle lines and progressive design innovations, such as the use of the low-wing concept, a retractable landing gear, a very thin wing profile, leading edge slats, landing flaps and a weapon firing through the propeller hub. Even the enclosed cockpit or the stressed skin fuselage wasn’t common four years before the start of the Second World War. Messerschmitt's Bf 109 was therefore a very promising project from the very beginning of its development, and it somewhat surprisingly won the competition over designs submitted by its more renowned competitors. The problems with the Jumo 210 powerplant, which was a component of the first phase of development, were only solved by replacing it with the more advanced DB 601. This, together with the later DB 605, is inextricably linked to the entire development and service of the Messerschmitt Bf 109. The inverted inline V-12 engine powered several tens of thousands of Bf 109s in more than 25 versions.
The first combat deployment of three test Bf 109s took place during the civil war in Spain, where these aircraft were sent in December 1936. Preproduction aircraft were primarily intended to demonstrate the capabilities of the plane in modern aerial warfare. Subsequently, series machines of the Bf 109B-1 variant began to see combat deployment with 2.J/88 Legion Condor. Germany also used sports competitions to demonstrate its air prowess. The success of the Bf 109E prototypes at the air show in Zurich in the summer of 1937 was additionally complemented a few months later by the establishment of a world speed record of 610.95 km/h. The Bf 109E was a breakthrough version, replacing the Jumo 210 engine with a more powerful and reliable Daimler-Benz DB 601 unit driving a VDM 9 three-blade variable pitch propeller. Production of the E-1 versions armed with four 7.9 mm machine guns and the E-3 armed with two 7.9 mm machine guns plus two 20 mm MG-FF cannon ran in parallel from the beginning of 1939. Thus, the Luftwaffe entered World War II armed with the most modern and powerful single-engine fighters of its time, forming the backbone of its units until the spring 1941. From the invasion of Poland through the Sitzkrieg on the Western Front, the invasion of Norway, the Battle of France and the Battle of Britain, the Bf 109E ensured the technical and tactical superiority of the Luftwaffe over its opponents. After the Battle of Britain in the autumn of 1940 and in the winter months of the following year, however, it became increasingly clear that the time was ripe to replace the Emils with a more potent successor.
This would become the Bf 109F, the development of which had in fact already begun during the preparation for series production of the Bf 109E in the autumn of 1938. The new project was designed around the new DB 601E engine with an estimated maximum power of 1350 hp, compared to 1055 hp for the DB 601A engine. In addition to the use of a more powerful engine, the intention of the design team led by chief designer Robert Lusser was the overall aerodynamic refinement of the airframe, combined with the introduction of a number of technical improvements. It saw the light of day by way of a complicated development, leading through prototypes and the pre-production Bf 109F-0, built mostly around the Bf 109E airframe and still carrying significant elements of the original design. In summary, all design changes were reflected in the first series version, the Bf 109F-1, radically different in shape from both the Bf 109E and the prototypes and the pre-production Bf 109F-0. Since the DB 601E engine was not yet available during the long development of the various concepts incorporated into the new design, the prototypes and pre-production Bf 109F-0 were powered by DB 601A engines, as was most of the Bf 109E production. Production Bf 109F-1 and F-2 aircraft were powered by DB 601N engines, and only the Bf 109 F-4 version received the planned DB 601E. Before we deal with the development of individual versions of the Bf 109F, it will be appropriate to first familiarize ourselves with the development of the power egg, the DB 601 engine, and also the evolution of the engine cooling system.
Bf 109 F-0 WNr. 5604 VK+AB. The aircraft with the DB 601 A engine already had the compressor intake with a circular cross-section. It was used to test the newly designed glycol cooler flaps combined with landing flaps. The wing still had the straight ends of the Bf 109E. Photo: SDASM
USED IN DEVELOPMENTAL VERSIONS
OF THE Bf 109F
The DB 601 engine was a development of the DB 600 carburetor equipped engine, development of which began in July 1933. It was a liquid-cooled inline turbocharged inverted twelve-cylinder unit of 33.9 L displacement, with a single-stage supercharger and carburetor. In the A version, it offered 986 hp, with gradual development it worked its way up to 1036 hp in the DB 600 Ga version. The first Bf 110 V1 prototype with DB 600 engines reached a speed of 505 km/h (314mph) on May 12, 1936. The DB 600 of various versions also powered the first versions of the He 111 B, G, etc. However, problems with the supply of these engines led to their replacement by more readily available units, mainly the JUMO 210 engine, which in the D version also powered the first versions of the Bf 109B, C and D.
The fundamental innovation of direct fuel injection into the cylinders of the DB 601 series made a significant contribution to the advancement of the line and in the further development of the Bf 109 and Bf 110. The DB 601Aa, production of which began in March, 1937, had the same displacement as the DB 600 at 33.9 liters ,and the compression ratio of 6.8:1 was also the same. Also unchanged were the bore and stroke of the cylinders (bore 150 mm, stroke 160 mm). The DB 601A used 87 octane B4 gasoline, introduced as the standard aviation gasoline in early 1939. Maximum power output of 1160 hp (1175 PS) at 2500 rpm was achieved by the DB 601A at an altitude of 1700m (5577ft). However, this output was only achieved for a short time when the engine's filling pressure was increased to 1.40 atm. The use of boost was limited to one minute. On the ground, the highest power with the same parameters was 1085 hp (1100 PS). At a filling pressure of 1.30 atm and 2400 rpm, the highest (combat) power on the ground was 986 hp (990 PS) and at an altitude of 2100m (6890ft), this was 1055 hp (1070 PS).
In the following version, the DB 601N, higher performance was achieved by increasing the compression ratio to 8.1:1 and introducing 100 octane C3 aviation fuel. The bore and stroke of the cylinders remained the same as in the DB 601A and DB 600. Using an emergency boost pressure of 1.42 atm at 2,600 RPM, 1,321 hp (1340 PS) could be produced at an altitude of 2,100 m and 1,233 hp (1250 PS) on the ground. The use of boost was possible for three minutes. Combat performance at 1.30 atm boost pressure and 2400 RPM provided 1,168 hp (1,185 PS) at 2,100 m and 1,085 hp (1,100 PS) at sea level.
The further improvement in the performance of the DB 601E engine was not achieved by further increasing the boost pressure or the octane rating of the engine. The DB 601E engine actually reverted to the easier to produce B4 gasoline with an octane rating of 87. The compression ratio was 7.0:1 on the left side cylinders and 7.2:1 on the right side, and was thus lower than the DB 601N. The cylinder bore and stroke were the same as in the DB 601A and DB 601N, bore being 150 mm and the stroke 160 mm. As a result, the displacement was also the same at 33.9 l. That's about all that remained the same. There were a lot of new and modified parts: a new engine block, metering pump, boost pressure regulator, injection pump drive housing and mixture regulator for the injection pump, new reinforced connecting rods, rocker arms, connecting rods, new intake manifold and rebuilt engine cylinders with larger intake manifold and modified valves.
Using an emergency engine boost pressure of 1.42 atm, at 2700 RPM, the highest output was 1,420 hp (1,440 PS) at an altitude of 2,100 m and 1,331 hp (1,350 PS) at sea level.
Combat power at 1.30 atm boost pressure, 2,500 RPM was 1,262 hp (1,280 PS) at 2,100 m and 1,183 hp (1,200 PS) at sea level.
The development of the new version of the DB 601 engine was long and rather complex, starting at the end of 1938, with series production of the zero series of 180 units (later increased to 290 units) beginning at the Werk 90 factory in Berlin-Marienfeld in the second half of 1940. Then, in January, production at the Büssing factory in Braunschweig and Henschel in Kassel was initiated. When the engines were introduced into service, they had cooling problems, which led to a limitation of the maximum permissible engine power during take-off and climb. There were also problems with the life of the piston rings and the bronze valve bushings. There were also problems with the spark plug cables, which quickly wore and burned out. For these reasons, most engines had a service life of only 50 hours, with few engines reaching 100 hours, which was a far cry from the expected 100 service hours to a midlife overhaul and 200 service hours to a general overhaul. Back in May 1942, during a joint inspection by the procurator of the Daimler-Benz company, von Berg and Colonel Galland (at that time in the capacity of the Fighter Air Force Inspector-General der Jagdflieger), a critical situation was discovered for the units on the Eastern Front, armed with the Bf 109 F-4, stemming from the unsatisfactory condition of the engines. Heavy engine wear threatened to ground a large part of the machines in operation and significantly reduce the combat capability of the fighter units. It can be seen from this that although there was a remedy by modifying the problematic components, such as the introduction of steel valve bushings and vented wiring harnesses, this remedy was time consuming and engine problems accompanied the Bf 109F-4 for practically the entire first year of their service. That is, the entire time of their front-line service, because in the summer of 1942 the first Bf 109 G-2s with DB 601A engines were already making their way to Luftwaffe fighter units.
Ground crew maintaining the weapons of Bf 109 F of JG 54 “Grünherz” on the Eastern Front in 1942. Photo: Bundesarchiv
Bf 109 F-4/Z during an oil refill. The aircraft has circular wheel wells, a larger compressor intake and a VDM 9-12087A propeller with wider propeller blades. Photo: Bundesarchiv
AVIATION FUELS IN THE LUFTWAFFE
Two synthetic aviation fuels were used in the DB 601 series of engines. Both were produced from brown coal by Fischer-Tropsch. The final mixtures, depending on the required type of fuel, were produced in the so-called WiFo depots (Wirtschaftsforschungsamt) according to the requirements of the individual branches of the armed forces.
B4 Flugmotorbenzin was a synthetic gasoline with an octane rating of 87. It contained tetraethyl lead and 25% aromatic additives. It was colored dark blue, and it was graphically symbolized by a yellow triangle outlined in white with the number 87 or B4 in it. It was the synthetic equivalent of B2 gasoline, produced from petroleum.
C3 Flugmotorbenzin was a synthetic gasoline with an octane rating of 100. It contained tetraethyl lead and 45% aromatic additives. It was colored dark green, and it was graphically symbolized by a yellow triangle outlined in white with the number 100 or C3 in it. This was the synthetic equivalent of C2 gasoline, produced from petroleum.
For a more detailed explanation of the meaning behind the octane rating, please see.
Sudetendeutschen Treibstoffwerke AG Brüx, located between Most and Litvínov in northern Bohemia, was the third largest producer of synthetic gasoline in Germany and the occupied territories. Construction of the plant began in May 1939, and the first train of synthetic gasoline was dispatched from STW Brüx on December 15, 1942. Albert Speer, Reich Minister of Armaments, attended the opening ceremony. The plant was producing up to 50,000 tonnes of synthetic fuel per month at full operation. In the last year of the war, after the Allied bombing offensive against the German fuel industry began, it became a frequent target of Allied air raids, mainly led by the 8th USAAF from Britain and the 15th Air Army from Italy. The first raid on this chemical plant on 8. USAAF carried out on May 12, 1944, and 12 more major American raids followed by the end of 1944. A heavy night raid was carried out by 231 Lancasters of RAF Bomber Command on January 16, 1945, virtually putting the factory out of action for the rest of the war. Photo: Edward D. Beneš archives, Aviation archives of Northen Bohemia
The nitrous oxide (N2O) injection system of the GM-1 engine cylinders allowed for a short-term increase in engine power at high altitudes (above 9,000m or 29,500ft). The principle of increasing performance is that when the mixture burns in the cylinder, nitrous oxide is decomposed into oxygen and nitrogen. Nitrogen cools the mixture and oxygen causes the mixture to become lean (the mixture contains more oxygen than fuel). Thanks to this, it is possible to add more fuel to the mixture, without the need to supplement the boost pressure with the compressor, because the necessary additional amount of oxygen to burn the fuel in the cylinder is obtained by the decomposition of nitrogen oxide. For this reason, the GM-1 system was used at high altitudes. To increase performance at altitudes of up to 8,000 m (26,250ft), the water injection system MW 50 or MW 30 was later used, which reduced the temperature of the mixture by evaporating the water in the cylinder, but did not generate the necessary oxygen. This had to be supplemented by increasing the filling pressure with a compressor, but could no longer produce the necessary filling pressure at higher altitudes.
The GM-1 system increased the DB 601N and E engine power at 9,000 m and 2600 RPM by up to 246 hp (250 PS), and the aircraft's speed by as much as 90 km/h. Maximum N2O injection time was 3 minutes (Baumgartl – sources vary on the exact numbers.
Due to the anticipated use of the more powerful DB 601E engine, new radiators were developed for the Bf 109F and the engine cooling system was updated. The coolant radiators had a completely new design compared to those of the Bf 109E series of aircraft, which not only ensured a higher efficiency of the cooling system, but was also simpler to manufacture. The manufacturing complexity of the new radiators was said to be 50% that of the older Bf 109 radiators. Aluminum alloys were used extensively in the construction of the new radiators. Although the new radiators were larger, with a frontal area of 0.334 m2 compared to the Bf 109E's 0.292 m2, they were logically more efficient due to the cross fall, and they were also aerodynamically more advantageous due to the fact that they were embedded deeper into the wing. The air flow was regulated by two hydraulically opening flaps on the trailing edge of the wing, the opening and relative position of which were automatically controlled by a thermostat. At the same time, when the flaps were extended, the flap on the front of the radiator opened. If necessary, the pilot could bypass the automatic the automatic feature and set the coolers manually with a lever in the cabin. The cooling system was filled with 75 liters of a mixture of glycol and water, two separate overflow tanks of the cooling system, each with a volume of 5 liters, were located on the sides of the engine block (on the sides of the crankcase). In the Bf 109E, the U-shaped coolant overflow tank was located on the front of the engine block.
The cooling system of the Bf 109E and the first Bf 109Fs was extremely sensitive to damage, most often by gunfire. Any interference with the radiator or other part of the cooling system meant a rapid loss of coolant, followed by engine seizure. This was a problem common to all fighters powered by liquid-cooled inline engines. The P-51 Mustang, for example, had a large underbody radiator which was extremely susceptible to damage and a single lucky shot meant an almost immediate engine seizure and a total loss of the aircraft. Splitting the cooling system between two radiators, one under each wing, offered a theoretical advantage. But this was not the case with the Bf 109E and Bf 109F-1 and F-2, where the cooling system was a single-circuit affair with one pump. In February and March 1941, a design modification of the system was successfully tested on the test Bf 109E, consisting of the introduction of separation valves (Kühlerabschaltventile), which, in the event of damage to one of the radiators, enabled the pilot to close it and separate it from the other part of the cooling circuit. This modification (Kühlerabschaltung) was introduced into series production on July10, 1941 by regulation Änderungsmotteilung I 181. The earlier claim (Prien/Rodeike) that these valves were supplied as retrofit kits for previously produced aircraft has no basis in any known regulation and appears that such sets were actually never produced and delivered to units. To the contrary, new aircraft on the production line were equipped with separation valves as standard, which, given the date of the regulation, would involve aircraft from the F-4 version on. The claim from the same source that the shortage of these kits and the high demand for them led to a race by groundcrew to cannibalize these items from shot down and damaged aircraft seems to be a reasonable one, where most of the Bf 109F-2s produced and part of the F- 4 (as well as all Bf 109 Es still in service) did not have these valves. Even the Bf 109F-4s produced had them as standard from the second half of July 1941 at the earliest, and possibly even later. The use of these valves cannibalized from aircraft that were no longer combat capable makes sense. A claim regarding the stopping of the installation of these valves in the Bf 109G is probably also erroneous. These valves are, for example, documented on a British captured Bf 109 G-2 carrying the W.Nr. 10639.
The oil cooler was located as in the Bf 109E, under the engine. Like the coolant radiators, it was a new design, developed for use with the DB 601E engine and was already installed in the Bf 109F-1 powered by the DB 601N. The Fö 699B oil cooler (9-6130A – Vogt) had a frontal area of 590 cm2 , the two-position control flap at the outlet of the cooler (outlet edge) was hydraulically opened and automatically controlled by a thermostat. It had only two positions, closed/open, the difference between the two positions was 4 cm. The control hydraulics were not connected to the aircraft's hydraulic system as such, but used oil from the engine's oil pan. This amounted to 35 liters of oil (and 8 liters of air) in the DB 601N engine, and 36.8 liters of oil and 6 liters of air for the DB 601E. The Bf 109F-4/Z and part of Bf 109 F-4 Trop production were fitted with the new Fö 870 radiator (9-6150 Vogt). It had a frontal area of 650 cm2 and a depth of 250 mm. Vogt also states that the first F-4/Z still had the original smaller radiator Fö 699B) with a frontal area of 590 cm2. The hydraulic system of the Bf 109F was expanded compared to the Bf 109E and, in addition to retraction of the main landing gear, also controlled the retraction of the tailwheel and the regulating flaps of the coolant radiators
PRODUCTION VERSIONS OF THE Bf 109F
As already mentioned, the design of the Bf 109F underwent radical modernization and overall aerodynamic fine-tuning. Apart from the aerodynamic refinements in the nose, the introduction of a new spinner and air intake to the circular compressor, a visible change of the Bf 109F compared to the Bf 109E was the absence of horizontal tail struts. The change in the armament arrangement was radical. Compared to the Bf 109E, this was reduced to an MG-FF fuselage cannon firing through the propeller hub and two 7.9 mm MG 17 machine guns above the engine. Due to the delay in the development of the DB 601E engine, the DB 601N engine was used to power the Bf 109F-1.
Development delays also prevented the use of the planned MG 151/20 or MG 151/15 cannon, so the MG-FF (engine-mounted) cannon with a 60-round magazine was used. The propeller was the VDM-9.12007.10. The wing received an elegant wingtip curvature with a cut-out for a position light on the leading edge and, above all, new radiators, as described above, the control flap of which also formed the inner part of the flap system. The slats remained automatic as on the Bf 109E, the control surfaces with metal internal construction were fabric covered. The tailwheel was retractable. The fuselage fuel tank, located under and behind the pilot's seat, had a volume of 400 liters, the Bf 109F-1 not being equipped to carry a drop tank. The aircraft received the FuG VIIa radio, and in 1941 some were retrofitted with the FuG 25 IFF system. The sight was the REVI C12/D reflector. An important feature was variable VDM-9.12007.10 propeller, the switch between automatic and manual modes being located under the throttle lever.
Bf 109 F-0 PH+BE already had oval wingtips, but the intake turbocharger had a rectangular cross-section, characteristic of the Bf 109 F-1 produced by the WNF factory. Photo: SDASM
The maximum speed is stated to be 595 km/h (370mph) at 5,200m (17,050ft), and 495 km/h (310mph) at sea level in combat mode. The rate of climb was 17 m/s (56ft/s), range 700 km (435 miles), with a ceiling of 12,000m (39,400ft). It is somewhat complicated when it comes to performance data, as sources differ somewhat. The figures presented here come from the records of the Test Center in Rechlin (E-Stelle Rechlin), and they are listed in their books on the development of the Bf 109 by M.Baumgartl and H.H. Vogt. M.Baumgartl also reports a maximum speed in emergency mode of 615 km/h (383mph) at 5,200m (17,050ft) and 515 km/h (320mph) at sea level.
Series production ran at the Bayerische Flugzeugwerke (Messerschmitt – Mtt. Reg) in Regensburg from July (Prien/Rodeike) or August (Murawski) 1940, while Vogt and Valtonen quote the start of production as October 1940, but this does not seem likely. By February 1941, apparently 137 machines were produced by Mtt Regensburg (Vogt, Valtonen and Rodeike state 157 units). In November 1940, production of the Bf 109F-1 also began at the Wiener Neustädter Flugzeugwerke (WNF) facility, where up to fifty aircraft were produced by January 1941 (Vogt, Valtonen, Prien/Rodeike claim 49 machines). The aircraft produced by the WNF factory are different from those made by Mtt. The Regensburg examples differed in details, such as the intake to the compressor having a rectangular cross-section, and probably also the shape of the aerodynamic transition between the wing and the fuselage, where there was a small symmetrical bulge above the wing spar connection pin to the fuselage, similar to the Bf 109E, as opposed to the Bf 109F and G fairing, which had an irregularly shape.
The new aircraft began to trickle to frontline units during the fall of 1940, but none of the combat units were ever completely re-equipped with the F-1 version. Stab/JG 51 was the first to receive them at the beginning of October. Major Werner Mölders made the first two combat flights on October 9th, 1940 with Bf 109F-1 WNr.5628 SG+GW, and by October 11th, he had shot down a Spitfire Mk.I from No.66 Squadron, RAF over Folkestone. It was Mölders 43rd kill, and the Spitfire pilot, P/O Pickering, survived the encounter with some injuries. In early November, several Bf 109F-1s were also received by I./JG 51, which suffered its first loss when the commander of 1./JG51, Oblt. Georg Claus, was shot down over the British coast. Smaller numbers of Bf 109F-1s were given to the replenishment groups (Ergänzungsgruppen) of JG26 and JG51 during November, with other units in France receiving individual pieces in early 1941.
Bf 109 F-4 od 10. (Jabo)/JG 2 in France during the summer of 1942. The aircraft sports reinforcing stringers on the rear fuselage. The photo shows the typical position of the open landing flaps and the combined glycol cooler and landing flaps. Photo: SDASM
As was usual when introducing new equipment to combat units, a number of defects and shortcomings appeared rather quickly. In addition to problems with the brakes and tire quality, a problem was found with the seat being positioned too far forward, which caused problems when pulling the control column back. The question remains whether this was the original seat of the same type used in the Bf 109E, or the new type with a separate seat and backrest integrated into the rear wall of the cockpit. Some F-2s were fitted with the same seat as the Bf 109E, later machines and at least most F-4s had the aforementioned new seats. It is not entirely clear whether the new seats were replacements for unsatisfactory older seats, or whether the new seats were not satisfactory and were in some cases replaced by proven older seats, as indicated by some sources.
But the most serious problem was the insufficient integrity of the rear fuselage. In February 1941, three planes were lost when strong vibrations from the engine, transmitted to the structure of the aircraft, caused the failure of the tail section. The investigation of a fourth accident revealed structural problems and insufficient structural integrity of the connection of the tail unit with the last fuselage bulkhead. The problem was temporarily solved by adding four external stiffeners, two on each side of the fuselage at the last bulkhead. Most Bf 109F-2s built were later equipped with these reinforcements.
Oberstleutnant Werner Mölders, Commodore of JG 51, pictured with Oberleutnant Georg Claus (centre) in late 1940. Claus served as Mölders' Adjutant until October 18, 1940, when he was appointed commander of 1./JG 51. He was killed in aerial combat over the Thames Estuary on November 11, 1940, becoming the first airman shot down in a Bf 109 F-1. Photo: Bundesarchiv
In November 1940, large-scale production of the first major version of the Bf 109F, the dash two, began at the AGO facility in Oschersleben, and began reaching combat units in January 1941. That same month, production also began at the WNF plant in Wienerneustadt, and later in the spring, it was also undertaken at Arado in Warnemünde, Messerschmitt in Regensburg and Erla in Leipzig. The F-2 version was again powered by the DB 601N engine, but this time the main armament was the new 15 mm MG 151/15 engine mounted cannon fed by a 200 round magazine located in the left wing root. Loading the cannon was not exactly a comfortable task due to the limited access to the magazine through two relatively small holes in the upper wing surface.
The increase in range by about 500 km (310 miles) was made possible by the installation of a drop tank under the fuselage, carrying 300 l (66gal), the same that already equipped the Bf 109E-7. The system of pumping fuel from the auxiliary tank to the main fuel tank was based on the principle of pressurizing the auxiliary tank with compressed air, dispensing the need for a fuel pump. It should be noted that photographs of the Bf 109F-2 carrying the centerline drop tank are very rare.
The Bf 109F-2 could also be modified for the fighter-bomber role by installing an ETC 500/IXb bomb rack under the fuselage to carry a 250 kg (550lb) SC 250 aerial bomb, or an ETC 50/VIId combined bomb rack for four 50 kg (110lb) SC 50 bombs. The designation of the bomb capable version was Bf 109F-2/B or Bf 109F-2/Bo.
Bf 109 F-4 Trop prior to delivery to JG 5, which operated in Finland. The aircraft already had a yellow band on the fuselage painted, which was the identification marking for the Eastern Front aircraft. The tropical camouflage of sand RLM 79 Sandgelb on the upper surfaces and blue RLM 78 Hellblau on the lower surfaces was complemented by fields of grey RLM 74 or 75 on the upper surfaces. The aircraft carried an additional 300 liter fuel tank. Photo: SDASM
In terms of performance, H.H. Vogt states a maximum speed of 630 km/h (390mph), and at sea level, 528 km/h (330mph). According to Vogt, the rate of climb is the same as that of the F-1, 17 m/s (56ft/s), a range of 700 km (430 miles), and a service ceiling of 12,000m ((39,300 feet). M. Baumgartl, in a performance table derived from the British Research iInstitute R.A.E. at Farnborough, gives a top speed at 6,629 m (21,750 ft) 597 km/h (371 mph), 491 km/h (305 mph) at sea level. The Soviet institute NII VVS gives a top speed 561 km/h (350mph) at 2,900m (9,500ft) and 510 km/h (317mph) at sea level. The British data in this case are consistent with the German figures for the Bf 109F-1. All in all, this would correspond to the fact that both versions, the F-1 and F-2, were powered by the same engine with the same performance, while the differences in the design of the aircraft were essentially negligible.
The F-2 also had a number of shortcomings that manifested themselves in service. A report from early April, 1941 by the commander of Luftflotte 2, General-Field Marshal Kesselring, described twenty-four defects of varying degrees of severity. These were gradually addressed on the production line, but most were resolved with the next production version, the Bf 109F-4. A total of 1,586 Bf 109F-2s (Vogt) were built, production ran in parallel at five factories: Mtt Regensburg (228 units produced), Erla Leipzig (219 units), AGO Oschersleben (378 units), WNF (169 units) and Arado Warnemünde (358 units), where production ended in August 1941.
This version was a direct development of the F-1, and featured a combination of the DB 601E engine and the MG/FF engine mounted gun. Production was stopped after 15 aircraft had been built after the new more powerful MG 151/20 cannon became available.
Production of the final and most powerful version of the Bf 109F, the dash-4, began at the WNF factory in May 1941, and the Erla factory in June. The first Bf 109F-4s arrived at front line units in June, 1941. The main update offered by the F-4 was the finally completed and fine-tuned DB 601E installation, driving a three-blade, variable VDM 9-12004.10 propeller. Armament was also improved via the installation of the engine mounted 20mm MG 151/20 cannon with 200 rounds. The fuselage machine guns remained the same, being 7.9mm MG 17s. A redesign and strengthening of the rear fuselage was carried out, thanks to which the need for external reinforcement was eliminated. Nevertheless, in the photographs of some Bf 109F-4s, the external reinforcements are still visible. A possible explanation for this is the use of older F-2 airframes either in initial production or over the course of subsequent conversions. The FuG 25 IFF unit was replaced by the more modern FuG 25a in the spring. The wing already had position lights as standard with a cover copying the shape of the wingtip curvature, introduced on later Bf 109F-2s. The wheel wells were either circular in shape, copying the shape of the tire, or angular, the same design as on the Bf 109E. The round design of the wells was more common. Here, it is reasonable to consider the use of F-2 airframes during conversion to F-4 standard by installing a DB 601E engine, or a different design of the wells from different manufacturers and production blocks.
JG 27 Bf 109 F-4 Trop in North Africa. Mechanics are cleaning the barrel of the MG 151/20 cannon. Photo: Bundesarchiv
Around 600 aircraft were equipped with GM-1 nitrous oxide injection system. These machines were designated Bf 109F-4/Z and had a larger 9-6150 (Fö 870) oil cooler, later standardized on the Bf 109G. These machines were also usually equipped with a VDM 9-12087A propeller with wider blades. A larger oil cooler was also part of the 576 tropicalized Bf 109F-4 Trop that were produced at the Erla factory in Leipzig. They also received a larger air intake to the turbo supercharger with a closable dust filter. Tropical equipment also included a vent on the top of the canopy windscreen and an emergency landing survival kit stowed in the rear fuselage containing a food pack, water and a Mauser K98 carbine. A larger air intake to the turbocharger was standard on later production Bf 109F-4s. Between December 1941 and April 1942, the WNF factory produced a total of 240 Bf 109F-4/R1s, allowing the installation of underwing nacelles housing MG 151/15 guns with 135 rounds of ammunition. However, gun nacelles were rarely used by combat units and they were widely used only later on the Bf 109G. Bf 109F-4s could also be converted to Bf 109F-4/B fighter-bombers, the bomb racks were the same as on the Bf 109F-2/B, but could not be fitted to the Bf 109F-4/Z or Bf 109F-4/R1 equipped with underwing gun nacelles. Some Bf 109F-4s were converted to photo-reconnaissance use as the Bf 109F-4/R2, R3, R4 and R8, which carried different types of photographic cameras. A total of 1,808 Bf 109F-4s of all versions were produced, including 1,034 at the WNF and 774 at the Erla factory in Leipzig. Production at the WNF factory ended in April 1942, and ERLA built the last Bf 109F-4 Trop in May of the same year. A month later, both factories, plus Messerschmitt A.G. in Regensburg, began production of the Bf 109G-2.
With respect to performance data, H.H. Vogt reports a maximum speed of 670 km/h (416mph), 540 km/h (336mph) at sea level. The rate of climb is stated by Vogt to be the same as for the F-1, 17 m/s (56ft/s), a range of 525 km (330 miles), and a service ceiling of 11,800m (38,700ft). M.Baumgartl gives in his performance tables sourcing the records of E-Stelle Rechlin a maximum speed 645 km/h (400mph) at 7,000 m (23,000ft), and 523 km/h (325mph) in combat mode. In emergency mode, he states a maximum speed of 670 km/h (416mph) at 7,000 m (23,000ft) and 540 km/h (336mph) at sea level, which corresponds to the data presented by H.H. Vogt. The increase in performance compared to the Bf 109F-2 also corresponds to the use of a more powerful engine.
A photo reconnaissance Bf 109 Fs from the 4.(F)/123 in 1943 at Cherbourg. Photo: SDASM
Bf 109F-5 and Bf 109F-6
The Bf 109 F-5 was a high-altitude fighter and photoreconnaissance aircraft, based on the Bf 109F-2, equipped with the GM-1 boost system. One aircraft was built and further development was stopped due to the RLM's lack of interest. The Bf 109F-6 was to be a heavy fighter again based on the Bf 109F-2, with an MG 151/20 engine mounted cannon and two MG 17 fuselage machine guns, plus two MG 17 wing mounted machine guns. No aircraft were built. The designation Bf 109F-6/U was used by Stab/JG 26 in France for Bf 109F-2 W.Nr.6750, which in addition to the standard armament was equipped with two wing-mounted MG FF/M cannon, similar to the Bf 109E. The aircraft was tested by Obstlt. Adolf Galland, who shot down a Spitfire over the English coast with it on November 18, 1941. At the same time, Galland tested another non-standard aircraft with the type designation Bf 109F-2/U1, armed with two 13 mm MG 131 machine guns located in the fuselage above the engine instead of the standard MG 17s
COMBAT USE OF THE Bf 109F AND ITS ADVERSARIES
The Western Front, France
In the first months of deployment of the Bf 109F on the Western Front, their opponents were Spitfire Mk.I, II and Vs of various sub variants, as well as Hurricane Mk.I and Mk.IIs. The most powerful were of course the new Spitfire Mk.Vs, introduced into service at roughly the same time as the Bf 109F-2 and F-4. The known performance parameters of the Spitfire Mk.V are as follows:
The speed of the new Spitfire Mk.V in March 1941 was 595.5 km/h (370mph) at 5,944 m (19,500 ft). But even with the Spitfire, performance data is hard to pin down exactly. In six different Spitfires tested at the A & A.E.E. between March 1942 and August 1946, the top speed achieved at 5,486 m (18,000 ft) varied between 555 km/h to 571 km/h (345mph to 355mph). The climb to 4,877 m (16,000 ft) was recorded as between 4.05 min and 6.4 min, and 6,096 m (20,000 ft) was between 5.6 min and 10.25 min. The best performances was attributed to Spitfire Mk.Vb W3228 with a Merlin 50M engine in May 1943,and the worst by Spitfire F.Mk.Vc AB488 with Merlin 46 engine.
For the Spitfire Mk.II, top speed was 570 km/h (355mph) at 5,487 m (18,000 ft), top speed at 6,096 m (20,000 ft) was 563 km/h (350mph), and climb to 6,096 m (20,000 ft) was between 7 minutes and 9.8 minutes depending on the engine type. I don't want to burden you with a flood of data, but in general, according to known performance data, the Bf 109F-4, like the F-2, surpassed its opponents. However, the Spitfire Mk.V was able to keep up with the Bf 109F-4 in climb rate, but in speed, it lagged behind at all altitudes. Compared to the less powerful Bf 109F-2, it, of course, fared better. The Hurricanes, with their top speed of 504 km/h (313mph) at 6,096 m (20,000ft) and a climb to the same height of between 7.5 min and 8.2 min, were already significantly behind the Messerschmitts and were not equal term opponents for them.
The Bf 109 F-2 (W. Nr. 12764) was the first plane of F version to fall into RAF hands. Commander I./JG 26 Hptm. Rolf Pingel made an emergency landing near Dover on July 10, 1941 after an aerial battle. Photo: SDASM
In Africa, in addition to the aforementioned adversarial Spitfires and Hurricanes, the Bf 109F-4 faced American P-40 Warhawk fighters of various versions and the P-39 Airacobra.
The P-40B/C (Tomahawk Mk.IIa) had a maximum ground speed of 445 km/h (277mph), 544 km/h (340mph) at 5,000 m (16,400ft) and climbed to this altitude in 7 minutes.
The P-40E (Kittyhawk Mk.Ia) had a maximum speed of 575 km/h (360mph) at 4,750 m 15,600ft) and climbed to 5,000 m (16,400ft) in 8.1 minutes.
The P-39D Airacobra had a maximum speed of 576 km/h (360mph) at 4,572 m (15,000 ft), climbing to 5,000 m (16,400ft) in 6.4 minutes.
The Eastern Front – The Soviet Union
On the Eastern Front, the superiority of the Bf 109F over Soviet fighters is indisputable. At the time of the German attack, a large part of the Soviet air force consisted of Polikarpov I-16, I-15, I-152 and I-153 fighters, which were already significantly outdated. Newer designs in the form of the Yak-1, LaGG-3 and at higher altitudes the higher powered MiG-3 were rare in the first months and their losses were heavy during that period of the war.
I will present the performance parameters of two fighters that were produced in large series in the later period of the war by the Soviets, the Yak-1 and LaGG-3.
JG 54 Bf 109 F-4 on the Eastern Front in the care of mechanics. The position of the deployed automatic slat can be clearly seen in the picture. That was its usual position when the aircraft was parked and still. Photo: Bundesarchiv
The Yak-1 reached a top speed of 586 km/h (364mph) at 5,000 m (16,400ft), and 490 km/h (305mph) at sea level, and climbed to the 16,400ft level in 5.7 minutes. It was more or less comparable against to the Bf 109F-2, but obviously would find its life more difficult against the F-4 This is similar to the comparisons with the Mk.V Spitfires, which, in the latter stages of the war, also served in the Soviet Air Force, along with the other British and American types mentioned above.
The LaGG-3 fared significantly worse with a speed of 549 km/h (340mph) at 5,000 m (16,400m) and 457 km/h (284mph) at sea level, and would reach that 16,400ft level in8.6 minutes. However, like the Yak-1, it was produced in large quantities over the first half of the war and, despite also suffering heavy losses, was a tenacious opponent. Both types in their successive versions were opponents of various versions of the Bf 109 until the end of the war, and in their peak versions of the La-7 and Yak-3 were at least worthy opponents. It must be added that ultimately, these opponents were victorious, as were the Mk.IX Spitfires on the Western Front and in the Mediterranean.
Messerschmitts Bf 109 F from II./JG 54 “Grünherz” with camouflage characteristic of this unit in a picture taken in summer 1941 at the beginning of the campaign in the East. Photo: SDASM
This image was taken in late 1942 at the El Daba base scrap yard. In the foreground on the right are the fuselages of Bf 109 Fs from II. and III./JG 27. Photo: SDASM
Harald Helmut Vogt: Messerschmitt Bf 109 – Einsatzmaschinen-Das Nachschlachgwerk
Harald Helmut Vogt: Messerschmitt Bf 109 – Versuchs und Erprobungsträger und der Weg zur Serienproduction
Jochen Prien/Peter Rodeike: Messerschmitt Bf 109 F, G & K Series
Michael Baumgartl: Das jagdfugzeug Messerschmitt Bf 109: Technik, Eigenschaften, Leistung, Stückzahlen, Bewährung