AJ PRESS 18 MESSERSCHMITT Me109 Pt3 WW2 GERMAN LUFTWAFFE POLAND FRANCE NORWAY BRITAIN RUSSIA NORTH AFRICA DAK

SOFTBOUND BOOK in ENGLISH by ROBERT MICHULEC

POLISH CAMPAIGN SEPTEMBER 1939

FRENCH CAMPAIGN 1940

NORWAY INVASION)

BATTLE OF BRITAIN CAMOUFLAGE AND TACTICAL MARKINGS (GENERAL CAMOUFLAGE, NATIONAL INSIGNIA, TACTICAL IDENTIFICATION, JAGDGRUPPEN, JAGDSTAFFELN, STAB MACHINES, SCHLACHT GRUPPEN, UNIT BADGES, MISC MARKINGS, SPINNERS, VICTORY MARKINGS)

THE Bf109E EMIL IN DETAIL (FUSELAGE AND TAIL, WING STRUCTURE, SPARS & RIBS, FLYING CONTROLS. LANDING GEAR, POWER PLANT, ENGINE MOUNTS, ARMAMENT & ARMOR, MAIN FUEL TANK, OIL TANK, FUSELAGE MG17 LAYOUT, WING MG FF WING CANNON, SYSTEMS AND RADIOS, FUG VII RADIO INSTALLATIONS)

COCKPIT LAYOUT

ELECTRICAL SYSTEMS LAYOUT, FUELS SYSTEM DIAGRAM, ENGINE COOLANT SYSTEM, FLYING CONTROLS INSTALLATION

THE DAIMLER-BENZ DB601 ENGINE (GENERAL DESCRIPTION, CRANKCASE, MAIN BEARINGS, CYLINDER BLOCKS, SUPERCHARGER, SUPERCHARGER VARIABLE-SPEED HYDRAULIC DRIVE, THROTTLE AND BOOST CONTROL, INDUCTION SYSTEM, FUEL INJECTION SYSTEM, COOLANT SYSTEM, AIRSCREW GOVERNOR UNIT)

BF109E (BASIC LAYOUT, TAILWHEEL, FUSELAGE SIDES, DASHBOARD, MACHINE GUN INSTALLATION, UNDERCARRIAGE, RUDDER, WINGS, RADIO INSTALLATION, COWLINGS, CANOPY, SC 50 BOMB ATTACHMENT, SC 250 BOMB ATTACHMENT, 300-LITRE LONG RANGE TANK, GUN CAMERA, TROPICAL FILTER, SCHNEEKUFEN SKI LANDING GEAR)

THE PHONEY WAR

THE NORWEGIAN CAMPAIGN

THE BATTLE OF FRANCE 1940

BATTLE OF BRITAIN

ATTACK OF THE EAGLE ADLER TAG

THE Bf109F ENTERS COMBAT

THE CHANNEL FRONT 1941-42

OPERATION BARBAROSSA INVASION OF THE SOVIET UNION 1941 RUSSIA EASTERN FRONT

NORTH AFRICA AND THE MEDITERRANEAN 1941-42 DAK DEUTSCHE AFRIKA KORPS (HANS JOACHIM MARSEILLE – STAR OF AFRICA)

DEFENSE OF THE REICH

CAMOUFLAGE & MARKINGS

MESSERSCHMITT Bf109 VARIANTS

---------------------------------------------------------------------------------------------------------------------

Additional Information from Internet Encyclopedia

Dozens of Messerschmitt Bf 109 fighters, including the A, B, C, D, and E variants first saw active service in the Condor Legion against Soviet-supplied aircraft in mid 1937 as a testing ground for the new German fixed-wing fighter plane. The Bf 109 quickly replaced the Heinkel He 51 biplane fighter which suffered many losses during the first 12 months of the conflict. Of the Luftwaffe's Jagdgruppen, 136 Bf 109s were sent to Spain, and 47 of these, including Bf 109Bs, Ds and Es remained behind in service with the Spanish Air Force after the conclusion of the war in 1939. The Republican fighters were no match for the Bf 109, equipped mostly with Soviet built Polikarpov I-15 and Polikarpov I-16s the Republican forces suffered heavy losses to Nationalist and Condor Legion fighters. As many as 20 Bf 109s were lost in Spain to enemy action to both aerial combat and ground fire.

In late 1938, the Bf 109E entered production. To improve on the performance afforded by the 441–515 kW (600–700 PS) Jumo 210, the larger, longer Daimler-Benz DB 601A engine was used, yielding an extra 223 kW (300 PS) at the cost of an additional 181 kg (400 lb). A much bigger cooling area was needed to disperse the extra heat generated by the DB 601 and this led to the first major redesign of the basic airframe. Enlarging the existing nose mounted radiator sufficiently to cool the engine would have created extra weight and drag, negating some of the performance gains afforded by the increased power, so it was decided to move the main radiators to beneath the wings' undersurfaces immediately outboard of the juncture between the wing root and wing panel, just forward of the trailing edges' inner ends, leaving the oil cooler under the nose in a small, streamlined duct. The new radiator position also had the effect of counterbalancing the extra weight and length of the DB 601, which drove a heavier three-bladed Vereinigte Deutsche Metallwerke (VDM)-made propeller.[14] To incorporate the new radiators, the wings were almost completely redesigned and reinforced, with several inboard ribs behind the spar being cut down to make room for the radiator ducting. Because the radiators were now mounted near the trailing edge of the wing, coinciding with the increased speed of the airflow accelerating around the wing's camber, the overall cooling installation was more efficient than that of the Jumo engined 109s, albeit at the cost of extra ducting and piping, which could be vulnerable to battle damage. In addition, the lowered undercarriage could throw up mud and debris on wet airfields, potentially clogging the radiators.

To test the new 1,100 PS (1,085 hp, 809 kW) DB 601A 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 just fitted with the two MG 17s mounted above the engine.[16] 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 first saw combat during the final phases of the Spanish Civil War.

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 armour 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; owing to priority being given to equipping Bf 110s with this engine, one fighter gruppe was converted to this version, starting in July 1940.[21] 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, including 496 E-4s built as such: 250 E-4, 211 E-4/B, 15 E-4/N and 20 E-4/BN

Development of the new Bf 109 F 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 (Werknummer (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) CE+BP, W.Nr 5603, was fitted with new, semi-elliptical wingtips, becoming the standard wing planform for all future Bf 109 combat versions. 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. On all of these prototypes the fuselage was cleaned up and the engine cowling modified to improve aerodynamics.

Compared to the earlier Bf 109 E, the Bf 109 F 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. 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 versions of the standard Luftwaffe 300 litre drop tank, the Bf 109 F offered a much increased maximum range of 1,700 km (1,060 mi) compared to the Bf 109 E's maximum range figure of only 660 km (410 miles) on internal fuel, and with the E-7's provision for the 300 litre drop tank, a Bf 109E so equipped possessed double the range, to 1,325 km (820 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. 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 when the first F-1s 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.

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 6.53°.

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. 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.

The armament of the Bf 109 F 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 109 E, and Oberst Werner Mölders saw the single centreline Motorkanone 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. Mölders flew one of the first operational Bf 109 F-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 and 29 October 1940.

 --------------------------------------------------------------------------------------------------------------------

The Bf 109 G-series was developed from the largely identical F-series airframe, although there were detail differences. Modifications included a 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.

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 reconnaissance 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 109 F-4; displacement and compression ratio were increased as well as other detail improvements to ease large-scale mass production. Takeoff and emergency power of 1,475 PS (1,455 hp, 1,085 kW) was achieved with 1.42 atm (42.5 inches/6.17 lbs) of boost at 2,800 rpm. The DB 605 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 (38.9 inches/4.4 lbs). The full output was not reinstated until 8 June 1943 when Daimler-Benz issued a technical directive. 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. 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 in the high-altitude DB 605AS engine, 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.

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.

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.

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 the Erla Maschinenwerk sub-contractor involved in building new examples, and upgrading older examples of the Bf 109. Often misnamed 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.

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 formerly separate, added-on Beule blisters which had earlier covered the spent shell-casing chutes of the synchronized fuselage-mount MG 131s were completely integrated into the upper cowling panels, vastly improving their streamlining and allowed them to be 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 side 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.

Some versions of the G-6 and later Gs had a taller, wood-structure 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.

Referred to as the "bastard aircraft of the Erla factory" in the Luftwaffe's Aircraft Variants Book of December 1944, the G-10 was a Bf 109 G airframe combined with the new DB 605 D-2 engine, 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. Contrary to popular belief the G-10 were not rebuilt older airframes but new production. Early production G-10 may have had two data plates (usually with G-14 stamped onto it) as these airframes were originally intended to be used for G-14 assembly but were diverted to G-10 assembly.

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, later 605DB) 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.

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. 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. The standardization attempt proved to be a failure, 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. 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 7,5 km (24,600 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 cautious estimate based on the available records suggest that about 5,500 G-14s and G-14/AS were built.

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.

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. 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 × 135 mm/14 × 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 × 190 mm (26 × 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 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.[96] 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.[98] 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, although III./JG 26 were almost completely equipped with K-4s which were fitted with R IV:

...apparently all of the K-4s supplied to III./JG 26 were also equipped with 20 mm-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.

In addition there were problems with the 30 mm (1.18 in) MK 108 Motorkanone, which often jammed while the aircraft was manouevring in battle, leaving the pilot to fight on with the two heavy machine guns. The standard Revi 16C reflector sight was fitted, which was slated to be replaced later by the EZ 42 Gyro gunsight, although this never happened.

Power was provided in production K-4s by a Daimler-Benz DB 605DB/DC engine (very early K-4s used the earlier DM).The DB/DC engine had an adjusting screw allowing the engine to use either B4 + MW 50 Methanol Water injection equipment or C3 fuel (DB 605 DB) or C3 fuel, with or without MW 50 (DB 605 DC). Using B4 fuel with MW 50, the DB 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 DC ran on C3 fuel and could generate a potential 2,000 PS, but only when using C3 fuel with MW 50 and a boost of 1.98 ata, otherwise the power ratings were similar to that of the DB. 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.

Deliveries began in mid-October 1944. 534 examples had been delivered by the Messerschmitt A.G., Regensburg by the end of November 1944, and 856 by the end of the year. Regensburg delivered a total of 1593 by the end of March 1945, after which production figures are missing.[citation needed] 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 first 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.

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.[108] Without MW 50 and using 1.80 ata the K-4 reached 670 km/h (416 mph) at 9,000 m (26,528 ft).[109] The Initial Rate of climb was 850 m (2,790 ft)/min, without MW 50, and 1,080 m (3,540 ft)/min, using MW 50.[109]