Bf 109 G-2 W.No. 14246. The machine has the smaller landing gear wheels (650x150), with retractable smaller tail wheel  (290x110) and no bulges above the undercarriage wheel well on the upper surface of the wing. [SDASM]

Bf 109 G-2 and G-4

Text: Vladimír Šulc

After the successful operational use of the Bf 109 F-2 and F-4, powered by the updated DB 601N and DB 601E engines in 1941 and 1942, further development of the Bf 109 was based around the new DB 605A engine, a fuel injected inverted V-12 developed from the DB 601E. The designers most significantly increased its displacement from 33.9 l to 35.7 l by raising the cylinder bore by 4 mm. The compression ratio of the DB 605A was 7.3:1 for the left cylinder bank and 7.5:1 for the right, compared to 7:1/7.2:1 on the DB 601E. The highest boost pressure for both engines was the same, 1.42 atm for takeoff and emergency modes, but thanks to the modernization of the compressor, the speed of which was now automatically controlled by a hydro-mechanical clutch governed by barometric pressure at different altitudes, it was possible to maintain a constant boost pressure at different heights. This meant that the boost pressure did not drop with increasing altitude. All this, along with a change in the valve timing and other modifications, helped increase the maximum rpm from 2,700 to 2,800 at takeoff. Maximum power at takeoff rose to 1,454 hp compared to 1,331 hp for the DB 601E. Combat power at 18,700ft was 1,232hp, with emergency boost at the same altitude rated at 1,336hp, compared to 1,183hp in combat and 1,300hp emergency at 15,750ft for the DB 601E.

These changes led not only to an increase in performance, but also to a slight increase in weight from 700 to 756kg. The engine used 87 octane B4 aviation fuel and drove a Type 9-12087 propeller with wider blades. Due to the need for more efficient cooling of the more powerful engine, a larger Type 9-6150 (Fö 870) oil cooler, the same as that installed in the Bf 109 F-4/Z, was used. Interestingly, neither the Bf 109 G-2 nor the G-4 are documented as using the GM-1 and MW-50 booster systems, which were used on both the Bf 109F and the later Bf 109 G-6.

The first production version of the Bf 109 G-2, manufactured from May, 1942 initially at WNF and then also at Messerschmitt in Regensburg and at ERLA in Leipzig from June, was visually very similar to the Bf 109 F-4, but in fact introduced a number of changes. First of all, the fuselage structure was strengthened, especially in the area of the engine bulkhead and in the rear part of the aircraft between the 8th and 9th fuselage bulkheads, where the need for strengthening was evident already in the Bf 109 F-4. There were changes in the cockpit, the bulkhead between the cockpit and the space for the MG 17 machine guns was redesigned and strengthened. While the Bf 109F had a zippered canvas separator between the instrument panel and the fuselage machine gun compartment, the Bf 109 G-2 and subsequent versions of the 109G had this partition made from an aluminum casting, which better sealed the cockpit from exhaust gases from the engine compartment and fumes from when the guns were fired, which was one of the persistent problems throughout the development of the Bf 109. On the sides of this partition were air-tight openings that could open and closed giving access to the MG 17 machine gun breeches and, if necessary, manually cock them. In the middle of the bulkhead were two sealed passages for the shaft of the propeller adjustment mechanism and for the mechanical tachometer. The main fuselage tank was modified to hold 400 liters of fuel and had armor plating composed of several layers of aluminum sheet and was covered with a three-layer rubber coating, which could seal punctures from rounds of up to 12.7mm caliber. The tank filler neck moved from under the left side of the canopy to between the second and third fuselage bulkhead. Optically and structurally, the canopy underwent significant changes, which resulted in the characteristic robust framing with an integrated armored glass panel at the front. The front plate of the windscreen was equipped with fuel spray. Spraying was started by a cock on the instrument panel which could only be opened in flight. The wing structure including the landing gear was strengthened, the tail wheel remained retractable with a tire size of 290 x 110mm. The main landing gear of the G-2 retained the wheels with tire dimensions of 650 x 150mm, the same as those of the Bf 109 F-4.

Bf 109G-2

Bf 109G-4

A significant change was the standardization of fasteners for the mounting of weapons and equipment on the airframe, which facilitated the later modernization of the aircraft to higher versions with the help of modernization kits (Rüstsatzen). This design strategy was retained for all G-version sub types from the G-2 to the G-10, and allowed the airframes of older machines to be suitable candidates for conversion to higher standard versions. It also made it easier to train and maintain staff on later variants. All versions of the Bf 109G were also produced with tropical modifications, although interestingly, the G-2/G-4 versions were still listed in documentation as two versions, the standard G-2/G-4 and the tropicalized G-2/ Trop and G-4/Trop. It should be stated, however, that this universality was put into practice only in part of the production of the Bf 109 G-6. Later G-6 models, and the following G-14 and later versions of the G-10 to include the G-6/AS and G-14/AS, dispensed with the tropical modifications, because developments at the fronts and related changes in the deployment of fighter aircraft brought the air force to the conclusion that they were no longer necessary.

Production of the subsequent Bf 109 G-4 began at Messerschmitt in September, 1942, at WNF in December of the same year, and at ERLA the following January. The G-4 version did not differ in appearance from the G-2 at the start of production, and it is not entirely clear why the new type number was applied. At first, the only significant change was in the radio equipment, where the G-4’s older FuG VIIa shortwave radios gave way to the new FuG 16 Z or FuG 16 ZY VHF units. In addition to the radios, the FuG 16 ZY equipment also had a built-in transponder for the Pegasus Y goniometric gunsight with a Moranmast rod antenna. Some machines were equipped with a ZVG 16 direction finding device with a PR 16 loop antenna on the back of the fuselage. This device was supplied as a Rüstsatz R7 Peilrufanlage set. In any case, despite this equipment being documented as standard for the Bf 109 G-4, in reality, very few actually were so equipped.

Bf 109 G-2 from III./JG 54 “Grünherz” on the Eastern Front in this picture taken in August 1942. This unit took delivery of the first G-2s in July 1942 and had them in service until January the following year. The G-4 version was delivered to III./JG 54 in February 1943. [Bundesarchiv]

During the production of the Bf 109 G-4, probably in December 1942, there was a change in the size of the wheels of the main landing gear. The installation of larger tires was a response not only to the increasing weight of the aircraft, but also to persistent problems with tire life and stability of the aircraft during take-off and landing. With the introduction of the Bf 109 G-2 into service, these problems were exacerbated. The Bf 109 G-2 had the same tires as the Bf 109F, 650 x150mm, tires that deflated quickly. This was thought to be due to the greater weight of the aircraft, but tests with the larger 660 x 160mm tires at Rechlin showed no improvement. On the contrary, the situation worsened when in some cases the tires were destroyed after only two take-offs and landings. During further tests, it turned out that the problem was caused by heat generated by the brakes, transferring onto the tires, the higher temperature of which caused the rapid degradation of the rubber. The solution was the introduction of larger steel brake discs, which did not heat up as much. However, due to the angle of the wheel's transverse axis to the axis of the landing gear strut (9°33"), the wheel with a larger brake drum and a larger tire could no longer fit in the wheel well. This was solved by adding a bulge into the upper wing over the wheel well. The tail wheel was enlarged to 350 x135mm, compared to 290 x110mm for the Bf 109 G-2. It continued to be fixed, on later series machines with a leather sleeve on the strut proper. Unfortunately, these characteristics are not definitive in differentiating between the G-2 and G-4 versions, as a segment of early production G-4s still had the original smaller wheels with a smooth wing without the fairing above the wheel well and a retractable tail wheel of smaller diameter. Additionally, older G-2s were retrofitted, usually during general repairs, to G-4 standard by installing larger wheels with the appropriate equipment.

Bf 109 G-4 and personnel of the Slovak 13th/JG 52 at Anapa airfield in Crimea in the summer of 1943. [Bundesarchiv]

A total of 1,586 Bf 109 G-2s were produced from May to December 1942 and 1,242 Bf 109 G-4s from September 1942 to June 1943, plus one license built Bf 109Ga-2 and 24 Bf 109Ga-4s were produced in Györ, Hungary. In addition to them, 167 Bf 109 G-1s and 50 Bf 109 G-3s with pressurized cockpits were produced. All versions could be equipped with an additional fuel tank with 300 liters of fuel or cannon pods with 20mm MG 151/20 cannons, or a belly bomb rack. But the aircraft usually carried either an additional tank or cannon pods. The simultaneous use of the tank and cannon pods was rare. You can find photos of such combinations, but this may have been a ferry configuration. Cannon pods were never combined with the fuselage bomb racks.

Bf 109 G-4 MT 213 still has the original smaller main landing gear wheels, but now has a larger fixed tail wheel (350x135). This machine is part of the color profiles in this kit, in a new camouflage applied after the overhaul. [SA Kuwa]

Combat Use of the Bf 109 G-2 and G-4

Both types gradually replaced the Bf 109 F-2 and F-4 in Luftwaffe fighter units over the second half of 1942. The Bf 109 G-2 ensured the performance superiority of German fighters over Allied opponents both on the Eastern Front during the successful German summer offensive and the advance of the German armies to the Caucasus and to Stalingrad, as well as in North Africa during the advance of the German Afrikacorps and its Italian ally along the North African coast towards Egypt. After the defeat of the German armies at El Alamein in North Africa in November, 1942 and the encirclement of the German 6th Army at Stalingrad in the same month, the tide had begun to turn. Luftwaffe fighters were unable to maintain their air supremacy over the battlefield at Stalingrad and keep the air supply lines open to the encircled German forces, nor in North Africa, where a strengthening Allied air force was successfully disrupting supplies to the remaining Axis armies in Tunisia. After the capitulation of the Germans and Italians in Africa, the Luftwaffe faced the Allied landings in Sicily and Italy, on the Eastern Front it waged intense air battles with a strengthening Soviet Air Force, supplemented in the spring of 1943 by new types of Soviet aircraft. Deliveries of British and American equipment were significant, especially the P-39 Airacobra and the P-40 Warhawk, supplied under the Lend Lease Act. In all these battles, the Bf 109 G-2 and G-4 were the most important equipment of the Luftwaffe fighter units. Both the Bf 109 G-2 and G-4's ability to carry MG 151/20 cannon pods under the wings was greatly appreciated in combat against the increasingly dangerous, heavily armored Soviet Il-2.

A photo reconnaissance Bf 109 G-2/R4 “Black 14” WNr. 10605 of the 2.(H)/Aufkl.Gr.14, shot down in Allied territory in Tunisia on February 20, 1943 with Oblt. Gerhard Wernicke at the controls. He managed to evade capture and after three days and a journey of 120 km got back to his own unit. [SDASM]

The importance of the Bf 109 G-4 with underwing gun pods, called Kannonenboot, increased in North Africa and the Mediterranean, where the number and intensity of Allied heavy four-engine bomber operations increased. In this area of operations in the spring and summer of 1943, the Luftwaffe’s Bf 109 G-4 was the main fighter type, whose lighter armament of one 20 mm cannon and two machine guns was less effective against heavy bombers. The reinforcement with two additional cannons was therefore most welcome. The number of the better-armed Fw 190A, whose armament of four 20 mm cannon and two 13 mm machine guns was much more effective against heavy bombers, was relatively low in the Mediterranean. In addition, they mostly served with combat units and were not deployed in battles against bombers. A significant part of the operational activity of the Bf 109G in the Mediterranean was in the employment of tactics against the Allied bomber formations, the organization of air traffic and the guidance of fighter elements to their targets. The Luftwaffe had well-developed operational tactics against smaller units of twin-engined bombers and their fighter escorts from fighting in Africa and on other fronts. The deployment of large groups of heavy four-engined bombers accompanied by strong fighter escorts, however, moved the air war to a higher level, and the command of German fighters in the Mediterranean, Jagdfliegerführer Sizilien, under the command of Lieutenant General Adolf Galland from June 1943, had great problems coping with the new situation in the air. However, the other side also had problems with the tactics and coordination of its forces, for which the deployment of large formations also presented a completely new challenge. The fierce battles over the Mediterranean and Italy in the summer of 1943 were thus accompanied by mistakes on both sides, from which both gradually learned, and they later benefited from the bloody experience when organizing air operations in all areas, especially on the Western Front.

Wernicke's “Black 14” became a favourite hack of the 86th Fighter Squadron (79th Fighter Group). Unit´s personnel took great care in improving its camouflage and markings. The name Irmgard belonged to the girlfriend of Wernicke's mechanic, who was Uffz. Bopp. [J. Ethell Collection]

On the Western Front, the ratio of the two main Luftwaffe single-engine fighters was reversed, units flying  the heavier Fw 190A being more prevalent. However, it was here that the Luftwaffe faced the greatest disaster. In the autumn of 1942, the first units of the newly formed 8th Air Force of the USAAF arrived in Great Britain, and increasingly took part in the bombing offensive against targets in occupied Western Europe. The first daylight raid on Germany was carried out by the 8th Air Army on February 27th, 1943, and from the spring of 1943 it increased its attacks in direct proportion to its increasing strength. Escalating British and American air raids on Germany were causing painful losses with an increasing impact on the German war effort. Not only was the increasing intensity of bombing attacks lethal for Luftwaffe fighter units, but the growing strength of the Allied fighter elements had to be contended with as well. The arrival of new types of American fighter aircraft and the associated change in Allied fighter tactics was deadly to German fighters.

In August 1943, the Messeschmitt plants in Regensburg and  WNF in Vienna's New Town were hit, and although in 1943 the Luftwaffe was still able to counter the American daytime raids relatively successfully, and even halting them for a time at the end of that year, the situation gradually became critical and by the following year the Luftwaffe had lost the air battle over Germany.

Lt. Hermann Weber of 3./JG 4 in his Bf 109 G-2 "Yellow 5", Mizil, Romania, summer 1943. Note the open acces door for the aircraft centroplane area. [JG 4 Archive / Museum of Air Battle over the Ore Mountains]

The Bf 109 G-2 and G-4 were direct participants in these historical events. The Bf 109 G-2 and G-4 were also used by the Finnish, Romanian, Italian, Croatian, Slovak and Hungarian air forces. In Hungary, the Bf 109 G-2 and G-4 were license-produced as the Bf 109Ga-2 and Ga-4. Romanian sources state that additional Bf 109 G-4s were built in Romania, but they were probably assembled from aircraft delivered by Germany.

In February 1943, production began of the Bf 109 G-6, which was produced in many blocks until the end of 1944. The exact number of G-6s produced is unknown, but it is believed to have reached 13,000 aircraft. However, the production of the Bf 109 G-4 ran parallel to the production of the Bf 109 G-6 until June 1943, and also in Luftwaffe fighter units, both types served concurrently from the spring and into the summer of that year. As late as July, during the Battle of Kursk, which marked the definitive turning point in the course of World War II, Bf 109 G-4s still equipped half of the Luftwaffe fighter units flying G version aircraft.

The tail surfaces of Bf 109 G-2 W.Nr. 14638, flown by the commander of 2./JG 4 Oblt. Hans Wilhelm Schopper during winter of 1942/43. Most of the on rudder depicted 34 victories were won before he joined JG 4, during combat in the ranks of II./Tr. 186 and III./JG 77. In addition to this aircraft, Schopper also flew the Bf 109 G-2 "Black 1" in the background. [JG 4 Archive / Museum of Air Battle over the Ore Mountains]

Conclusion

The Bf 109 G-2 and G-4 were transitional types in terms of production and development of the Messerschmitt Bf 109. Their importance lay in the successful adaptation of the airframe, initially modernized for the Bf 109F, to accept the new, more powerful DB 605A engine. The Bf 109 G-4 essentially represented the production pattern and, really, the mass production pattern, of the Bf 109 G-6 and other variants, such as the Bf 109 G- 14 and later, the Bf 109 G-10. The quality of the airframe construction is evidenced by the fact that the basic airframe remained a platform for mounting more powerful engines and weapons, while it changed only in peripheral areas. The engine fairing changed depending on the increase in the size of the compressor, the rudder was enlarged to improve control of the airplane, the wheel wells were widened as governed by subsequent enlargement of the tires, which was a response to the increasing weight of the aircraft due to the installation of heavier weapons and various auxiliary systems, such as the MW 50 and GM-1 booster systems. There was a change to the canopy and cockpit armor, where the aim was to improve ergonomics, the view from the cockpit and better protection for the pilot, and in the last months of the war there were attempts to replace some structural units, typically the tail surfaces, with wooden structures, which was a response to the overall deteriorating supply chain situation and lack of raw materials offered by the shrinking territory controlled by the Third Reich. But the basis of the airframe would remain the same, even in the case of the last development version, the Bf 109 K, where the most extensive design modifications took place in the aforementioned areas. But it was still, in modern terms, just a face lift. The basis of the airframe remained the same as it was fine tuned on the Bf 109 G-4.

The internal design changes and the overall fine-tuning of the airframe are probably the reasons why the designation was changed from Bf 109 G-2 to G-4. Other changes in the equipment of the aircraft were not the reason for changing the designation in the later period for the Bf 109 G-6. For the Bf 109 G-6, the differences in equipment and armament between individual production blocks were greater than that between the G-2 and G-4, and yet, the Bf 109 G-6 still retained its designation, even after the installation of the DB 605AS engine. The change occurred only after the installation of the DB 605D engine, when the designation changed to Bf 109 G-10.

However, it is uncertain whether this is actually the case. In fact, the reason why the designation was changed from G-2 to G-4 is still somewhat shrouded in mystery.

FUG16Z/ZY

The FuG-16Z/ZY working in the very short wave band (UKW/VHF) widths was a very modern and compact unit, almost timeless. The entire device, designated Geräteblock LA6NCA, consisted of three modules: the Emfänger E 16 Z/ZY receiver, the Sender S 16 Z/ZY transmitter, and the Bedlengerät BG 16 Z/ZY modulator. The assembly was located in the fuselage behind the cockpit. Tuning was remote from a control panel in the cockpit, located at the edge of the lower left corner of the instrument panel. The control panel had a rotary switch with four positions, below which were preset frequencies, indicated by pictograms. Under Pictogram I was the guidance frequency Y-Führungfrequenz, and under the Roman numeral II was the frequency for communication with the flight commander with his unit or fighter formation Gruppenbefehlfrequenz. Under the triangle was the airfield traffic control frequency Nahflugsicherungfrequenz and under the square was the frequency for all fighter planes Reichsjägerfrequenz. To tune to one of these, it was enough just to switch the selector to the correct position. Alternatively, the switch could have frequencies marked with standard numerals of 1 to 4, and an older version of the control panel had two rocker switches.

Bf 109G-12

Not even later did the Bf 109 G-2 and G-4 completely lose their significance, as they served until the end of the war in training units. Some of them were converted into two-seat Bf 109 G-12s by Blohm und Voss in Hamburg. These were also later converted from the Bf 109 G-6 and Bf 109 G-10. A total of 280 Bf 109 G-12s were likely built, but how many were converted from G-2s and G-4s is unknown. Some of the surviving airframes of the Bf 109 G-2 and G-4 were also used to convert to the higher derivatives of the Bf 109G, and after being withdrawn from service with front-line Luftwaffe units, Bf 109 G-4s continued to be supplied to Germany’s allies in 1944.

Bf 109G-12 (conversion from Bf 109G-2)

During their service with Luftwaffe training units, the majority of Bf 109 G-12s, which had been converted from Bf 109 G-4, received upgraded, higher-quality wheels standardized for Bf 109 G-6.