The powerful and deadly Messerschmitt Bf-109 was the mainstay of the Luftwaffe’s fighter arm throughout World War II, scoring more aerial victories than any other type. Thirteen Bf 109 pilots claimed more than 200 victories apiece, while two of these ‘Experten’, ‘Bubi’ Hartmann and ‘Gerd’ Barkhorn, each shot down more than 300 enemy aircraft. In the early years of the war, the speed, handling characteristics and firepower of the Bf 109E 'Emils' gave many Allied Hurricane and Spitfire pilots a nasty shock.
With a top speed of 690 km/h (429 mph) at 7,400 m (24,280 ft), a powerful 2,000 horsepower Daimler-Benz 605D engine and a pressurized cabin, the K-4 ‘Kurfürst’ was the best and final version of the Bf-109 to see service. Armed with one 30-mm Mk 108 cannon and two 13-mm Mk 131 machine guns, the K-4’s agility made it more than a match for most Allied fighters, while its blistering firepower made it the scourge of high-flying enemy bombers.
The ‘Kurfürst’ was also no slouch in the ground-attack role, carrying either a 500 kg or a 250 kg bomb.
Jump into your K-4, get airborne and tangle with Mustangs, Spitfires and Thunderbolts, or scythe your way down through massed Flying Fortress bomber formations.
Bf 109 is one of the most well-known fighters of WWII had humble beginnings. When first imagined in 1933, just as a new political party rose to power in Germany, few people could have imagined that this early interceptor research project would result in over 30,000 production examples serving throughout Europe in roles ranging from ground attack to reconnaissance, and providing a mount to most of the world's leading fighter aces.
Originally the aircraft was designated as Bf 109 by the RLM, since the design was submitted by the Bayerische Flugzeugwerke ("Bavarian Aircraft Works") during 1935. BFG was renamed Messerschmitt AG after 11 July 1938 when Erhard Milch finally allowed Willy Messerschmitt to acquire the company. All Messerschmitt aircraft that originated after that date, such as the Me 210, were to carry the "Me" designation.
The names "Anton", "Berta", "Caesar", "Dora", "Emil", "Friedrich", "Gustav" and "Kurfurst" were derived from the variant's official letter designation (e.g. Bf 109G – "Gustav"), based on the German spelling alphabet of World War II, a practice that was also used for other German aircraft designs.
When the Bf 109 was designed in 1934 by a team led by Willy Messerschmitt and Robert Lusser, its primary role was that of a high-speed, short range interceptor. It utilized the most advanced aerodynamics of the time and embodied advanced structural design which was ahead of its contemporaries. In the years of the Blitzkrieg, the Bf 109 was the only single-engine fighter operated by the Luftwaffe, until the appearance of the Fw 190.
The 109 remained in production from 1937 through 1945 in many different variants and sub-variants. The primary engines used were the Daimler-Benz DB 601 and DB 605, though the Junkers Jumo 210 powered most of the pre-war variants. The most-produced Bf 109 model was the 109 G series (more than a third of all 109s built were the G-6 series, some 12,000 units being manufactured from March 1943 until the end of the war).
The Bf 109 K 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. 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.
Externally the K series could be identified by changes in the locations of the radio equipment hatch, 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. 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 with two small clamshell doors covering the recess when the tail-wheel was retracted.
The wings featured the large rectangular fairings for the large 660x190 mm main wheels. Flettner tabs for the ailerons were also to be fitted to serial production aircraft to reduce control forces, but were extremely rare, with the majority of the K-4s using the same aileron system as the G series.
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.
Power was provided in production K-4s by a Daimler-Benz DB 605DB or DC engine (very early K-4s used the earlier DM). A wide-chord, three bladed VDM 9-12159A propeller of 3 m diameter was used, as on the G-6/AS, G-14/AS and G-10.
Using MW 50 and maximum boost the Bf 109 K-4 was the fastest 109 of World War II, reaching a maximum speed of 710 km/h (440 mph) at 7,500 m (24,610 ft.) altitude. Without MW 50 and using 1.80 ATA the K-4 reached 670 km/h (416 mph) at 9,000 m (26,528 ft). The Initial Rate of climb was 2,775 ft. (850 m)/min, without MW 50, and 3,563 ft. (1,090 m)/min, using MW 50.
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.
The pilot's office in the Bf 109K-4 is a conventional aircraft cockpit that is rather cramped and disorganized by late-war standards. A long series of improvements and adjustments in the Bf 109 variants meant that the original clean Bf 109B cockpit continued to receive a large number of switches and controls for new devices that were often placed haphazardly in areas convenient to the engineers with little regard for ergonomics.
The DCS: Bf 109 K-4 cockpit is a 100% six-degrees of freedom (6 DOF) cockpit that allows complete freedom of movement around the cockpit. This includes all panels, switches, dials, buttons being animated, rendered in the 3D, and with high-resolution textures. Both day and night lighting is available.
When the mouse is hovered over a cockpit control, a tool tip is displayed to indicate the controls function.
The flight dynamics of the Bf 109 K-4 are a further develops the Advanced Flight Model principles started with the Su-25 and then later improved to Professional Flight Model (A-10C, P-51D, Fw 190 D-9 etc.).
A multi-segmented wing provides natural damping; and each aerodynamic surface has a number of airspeed-sensitive points for accurate slipstream effect calculation. Slipstream location and direction depends on plane speed, angle of attack, angle of sideslip, prop thrust and wing lift. All prop side effects, such as slipstream, torque, P-factor are taken in account in overall flight model.
A true thermodynamic engine model for all engine modes from idling to maximal power is provided. Variable speed supercharger and manifold pressure regulator are truly modelled to achieve authentic power characteristics of the engine.
The second ("slow") model is used for engine start-up and stop. The true thermodynamic model is used for each stroke of each cylinder, providing individual firing in cylinders, natural plane rocking during the start, over-priming, in-flight prop stop, etc.
The Messerschmitt Bf 109K-4 fighter aircraft is a single-seat, low wing monoplane powered by a 12-cylinder liquid-cooled supercharged inverted Vee Daimler-Benz DB 605 piston engine. The engine is equipped with a two-stage centrifugal supercharger with a MW50 injection into the supercharger intake. The engine spins a three blade constant speed propeller.
The control unit assembly consists of the horizontal stabilizer and elevators, the vertical stabilizer and rudder, the ailerons, and the flaps.
The Bf 109K-4 has a conventional control scheme with surfaces that include a vertical stabilizer, rudder, horizontal stabilizer, two elevator, two aileron, and flaps.
The flight stick can be moved forwards and backwards in conventional fashion to control the elevator. The stick can be moved 15°30' forwards and 15°30' backwards.
As the entire tailplane can be trimmed in flight by using the Horizontal Stabilizer Trim Handhwheel, elevator deflection depends on tailplane position.
The flight stick can also be moved sideways to control the ailerons in conventional fashion.
Flap position is controlled via a handwheel located to the pilot's left. The flaps position scales are drawn on root part of flaps and visible from cockpit. Flaps can be deflected from 0 to 40°, with the 40° position reserved for landing, and 20° generally used for take off. One full turn of the flap handwheel is equal to roughly 5° of flap deflection; therefore four full turns are required for the Take-Off position, and eight full turns for Landing.
Tailplane position is controlled via a handwheel located to the pilot's left alongside the flap handwheel. Cockpit indicator is provided near the handwheel, with the round window on the mechanical indicator displaying the incidence level. Negative incidence is shown with a minus sign, e.g. -2.5, while positive incidence is shown with no sign, i.e. 1 means +1.
The tailplane can be moved from +1°10' to -6°.
The aircraft is generally easy to pilot when proper control forces is applied. However, the tendency of the left wing to suddenly drop on take-off and landing is the aircraft's Achilles heel. Precise rudder input is required to counter the yaw.
The Bf 109 features retractable narrow-track landing gear. Wheels are raised and lowered hydraulically. There is also an auxiliary manual system for operating the gear.
The tailwheel on the 109 went through many changes. While many earlier variants featured a fixed tailwheel, the K-4 reintroduces the retractable type that improves high-speed performance. The tailwheel also features two small clamshell doors covering the recess when the tail-wheel was retracted.
The undercarriage is controlled by simple push buttons located on the cockpit's left-hand side.
In case of hydraulics failure, the main gear can also be lowered by pulling the emergency gear extension handle. This unlocks the shock struts which can then extend with the help of gravity and sealed air jacks.
The tailwheel is retracted simultaneously with the main gear. It can be locked or unlocked via a control rod located by the pilot's left elbow.
The Bf 109K-4 has hydraulically operated brake shoes on each of the two main wheels. Each has its own hydraulic pump and brake lines. Each wheel can be braked individually.
The entire system is conventionally operated via rudder pedals.
Most of the Bf 109s were powered by various variants of the Daimler-Benz DB 601 V12 engine, or its derivative the DB 605. Same is the case for the Bf 109 K-4.
Engine supply situation has often been a weak spot for the German aircraft industry, and it was especially felt in 1944 and 1945 as the 109K was in production. A variety of DB 605 variants were installed on production K-4s. Initial plans to use the advanced DB 605L with a two-stage supercharger were foiled with a single lucky Allied bomb that took out a high-altitude test chamber, delaying 605L deliveries by nearly a year. As it is, production 109Ks shipped with DB-605B, DB 605DC, DB-605ASC, or DB-605ASC, with some very late production K-14s finally receiving the DB 605L.
The DCS Bf 109 K-4 is modeled with the DB 605 DB engine.
The DB 605 DB could use B4 fuel which, with MW 50 Methanol Water injection equipment, generated an emergency power rating of 1,600 PS at 6,000 m (1,160 PS maximum continual at 6,600 m), and take-off power of 1,850 PS at 0 m, with a maximum supercharger boost of 1.8 ATA. The DB could also be run on higher octane C3 fuel, but use of MW 50 was forbidden.
The large advantage of the Daimler-Benz engine is its direct fuel injection. While most Allied aircraft use complex and expensive turbo superchargers that require high-octane fuel, the DB 601 and its 603 and 605 derivatives could compete with them using low-grade 87-octane fuel due to the use of direct fuel injection.
The Daimler Benz DB 605 engine has a hydraulically driven single-stage supercharger, coupled with a MW-50 Water-Methanol injection.
MW-50 (MethanolWasser 50) is a 50-50 mixture of methanol and water sprayed into the Bf 109K-4's supercharger, allowing the use of increased boost pressures.
Many Bf 109 variants use some sort of boost. The G-6 was the first variant designed for a new field modification kit or Rustsatz model that allowed a large number of various standard kits to be quickly installed in the field, as well as a number of Umrutsatz, or factory kits that could be installed in the factory. The U2 kit provided for a 118-liter tank behind the cockpit used for the GM 1 nitrous oxide injection system, while the U3 kit used a tank for the MW 50 water-methanol mix.
At sea level, the engine runs at over 1800 hp with MW-50 enabled, compared to 1430 hp with the MW-50 off.
The boost provided by the MW-50 begins to decrease in power at altitudes above 6,000 meters.
The Bf 109K, as most Bf 109 variants, uses a single main 250-liter L-shaped fuel tank located partly under the cockpit floor and partly behind the rear cockpit bulkhead.
The Bf 109K-4 can also carry an external drop tank under the fuselage with the capacity of 300 liters.
The fuel system operates on a simple principle. When more than one fuel tank is used, all tanks are daisy-chained and fed into one another. A Fuel Selector lever located on the left side of the Front Dash allows the pilot to manage the system.
Two fuel pumps are provided, P1 and P2. P1 draws fuel from the rear section of the tank, while P2 draws fuel from the front of the L-shaped tank. A Fuel Cock lever located below the throttle quadrant is used to switch between the fuel pumps, with the options of ZU (both off), P1 (P1 pump), P2 (P2 pump), and P1+P2 (both).
The engine always draws fuel from the main tank.
When drop tanks are used, their fuel pump feeds the main tank. The Fuel Contents Gauge will continue to display full for as long as the drop tanks continue to feed the main tank. Once the drop tank is emptied, the fuel quantity in the main tank begins to decrease.
When drop tanks are used, the Fuel Selector Switch should be set to Hinten. The Fuel Contents Gauge will continue to display full for as long as the drop tanks continue to feed the rear and in turn the forward tanks. Once the drop tanks are emptied, the fuel quantity in the rear tank begins to decrease.
The hydraulic system in the Bf 109 is used to operate the landing gear and the wheel brakes.
The landing gear is normally raised and lowered hydraulically. There is also an auxiliary manual system for operating the gear.
The Bf 109K-4 also has hydraulically operated brake shoes on each of the two main wheels. Each has its own hydraulic pump and brake lines. Each wheel can be braked individually.
A circular oil tank is located in the nose. As no armor protection is provided for the oil system, the oil tank and the oil cooler are some of the aircraft's most vulnerable spots.
The oil system is used for the following:
The Bf 109 K-4 used two matching radiators partially recessed in the wings for cooling. First introduced during a radical redesign of the F for Friedrich variant, the system used a system of interconnected flaps to efficiently regulate cooling while providing the least possible drag. The flaps are controlled automatically by a thermostat that works to provide maximum cooling by moving the flaps in unison as needed.
The automatic system can be somewhat sluggish, especially on the ground. Common pilot tactic is to nudge the throttle slightly on take-off to reach the proper temperature limit, causing the automatic cooler flaps to open or close as needed.
Manual override for the system is also provided. It should be used in the case of emergency; during normal operation it is highly recommended to use the automatic system.
The electrical system is powered by a 2000-watt 24-volt generator. The system also contains one 7.5 Ampere-hour battery.
The electrical system powers the following:
The Circuit Breaker Panel on the right-hand side of the cockpit is used to power up the components.
Each circuit breaker has two buttons. The larger black button with a white dot switches the corresponding circuit on. Red button opens the circuit and switches it off.
Each circuit is designed to pop out if overloaded and can be reset by pushing the black button in.
The oxygen system consists of a cockpit-mounted flow valve with the attached flow monitor, the regulator unit with oxygen hose, and high-pressure lines with pressure gauge, and a set of spherical 2-liter bottles located in the right aircraft wing that contain the oxygen. The bottles are split into three banks of three as an additional safety measure.
Opening the flow valve starts the flow of oxygen. Oxygen flows to the regulator unit. The provided Flow Indicator and the Pressure Gauge located on the right-hand side of the Front Dash correspondingly indicate system status.
The aircraft if equipped with a FuG 16ZY radio, a specially-designed airborne VHF transceiver. The FuG 16 can be used for in-flight communication as well as for IFF identification and DF homing. The set operates in frequency range between 38.4 and 42.4 MHz.
The FuG 16ZY can also be set to Leitjager or Fighter Formation Leader mode that allows it to use a special Y-Verfarhen ground tracking and direction via the normal headphones.
The AFN2 component of the radio set allows easy navigation to ground-based homing beacons, showing both direction and range on one simple dial.
The FuG 25a operates in frequency range of 125±1.8 MHz, with the operating range of up to 100 km.
Armament of the K-4 consists 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 rounds per gun. Additional Rustsatze, 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).
An important fact that must be mentioned when discussing the armament is the quality of German ammunition. Largely ahead of its time and superior to comparable Allied examples, German cannon shells use centrifugal fusing in shells which contain several times more explosive than Allied shells due to the use of thinner walls. High-quality explosives used in the shells also provide considerably more punch than comparable Allied examples.
The Bf 109 uses electrically operated guns, as do most other German aircraft of WWII. This makes weapon selection easier than on Allied aircraft, and also enables a unique system of ammunition counters that takes all guesswork out of aerial gunnery.
Cockpit equipment for the armament includes the Revi 16B gunsight as well as the SZKK 3 ammunition counters. While provisions were made for the more advanced lead-computing EZ 42 gunsight, late-war production difficulties meant that production K-4s shipped with the simpler Revi 16B.
The SZKK 3 ammunition counter shows the ammo stores for each of the two MG 131. The left-hand vertical bank in the SZKK show the state of the left MG 131, and the right-hand indicator the right MG 131.
The ammo counters are not directly linked to the ammo stores. Instead, they are reset to full (top) position when the guns are loaded on the ground, and then each mechanical indicator bar is lowered by one notch whenever a weapon is fired.
Notches provided to the side of each indicator show the amount of rounds in the ammo store for each weapon.
White bar portion signifies ammunition in the stores; black bar portion signifies expended ammunition.
The Bf 109K-4 is also equipped with the Revi 16B reflex gunsight. It was slated to be replaced by the EZ 42 Gyro gunsight, but this never materialized due to late-war supply troubles.
The Revi 16B is a standard reflector sight used on many German aircraft. While attempts to introduce lead-computing sights began rather early in the war, the RLM continued to prefer simpler Reflex Sights (Reflexvisier or Revi for short) well into 1944. All reflex sights used by all nations use the same basic principle and project a reticule image onto a sight glass into infinity.
Reflector sights such as the Revi 16B do not compute lead and simply provide a dead aiming point relative to the aircraft gun line.
When using a reflex sight in combat, the pilot has to make manual adjustments to account for target lead, G load, distance to target, and other parameters required for accurate aerial gunnery.
