The Bf 109 G-series was developed from the F-series airframe although there were several differences. This series used the 1,475 PS Daimler-Benz DB 605. Modifications included reinforced wing structure, an internal bullet-proof windscreen, the use of heavier, welded framing for the cockpit transparencies, and additional light-alloy armour for the fuel tank and armouring of the radiators. 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.
The G-series was designed to adapt to different operational tasks with greater versatility, using field kits known as Rüstsätze. Special high-altitude interceptors with GM 1 high-altitude boost and pressurized cockpits were also produced.
The “new” Daimler-Benz DB 605A series was a development of the DB 601E engine utilised by the preceding Bf 109F-4. This was achieved through increasing the displacement and the compression ratio, as well as other detail improvements. The DB605 suffered from reliability problems during the first year of operation, forcing Luftwaffe units to limit maximum power output to 1,310 PS (975 kW) at 2,600 rpm and 1.3ata manifold pressure, until October 1943, when the full 1475 PS rating at 2800 rpm, 1.42ata manifold pressure was cleared for service use.
The early versions of the Bf 109G closely resembled the Bf 109F-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 MG 17 was replaced with the 13 mm MG 131 heavy 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 109G-6s nickname “Die Beule” (“The Bulge”). The Gustav continued to be improved constantly: cockpit visibility, firepower in the form of the 3cm MK 108 cannon was added to the basic design in 1943, and a new, enlarged supercharger for the DB605, an enlarged vertical stabilizer (G-5 onwards), MW-50 power boost in 1944. It has been suggested the added weight of the new engines and heavier armament adversely affected the handling characteristics of the Bf 109, especially since it already had a high wing loading. While technically the statement is true, it is somewhat unfair as analysis show only a modest increase in weight as a result of development, fairly comparable to the development trend with Western Allied fighters.
From the Bf 109G-5 on an enlarged wooden tail unit (identifiable by a taller fin 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 Gustav, 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 litre (66 Imp gal) droptanks, one under each wing, the latter received pressurized cockpits for pilot comfort and GM-1 nitrous oxide “boost” for high altitudes. The latter system was capable of increasing engine output for limited periods by 300 horsepower above the rated altitude and high altitude performance above of that of any Allied fighter in service in 1942-43.
The G-1 was the first of the G-series, starting production in February 1942. This was the first production Bf 109 with a pressurized cockpit and could be identified by the small, horn-shaped air intake for the cockpit compressor just above the supercharger intake on the left upper cowling. In addition the angled armour plate for the pilot’s head was replaced by a vertical piece which sealed-off the rear of the side hinged cockpit canopy. Small, triangular armour-glass panels were fitted into the upper corners of this armour, although there were aircraft in which the plate was solid steel. Silica gel capsules were placed in each pane of the windscreen and opening canopy to absorb any moisture which may have been trapped in the double glazing. The last 80 G-1s built were lightweight G-1/R2s. In these GM-1 nitrous oxide ‘boost’ was used, and the pilot’s back armour was removed, as were all fittings for the long range drop tank. A few G-1s flown by I./JG 1 are known to have carried the underwing, MG 151/20E 20mm cannon gondolas.
The G-2, which started production in May 1942 lacked the pressurization and GM-1 installation. The canopy reverted to one layer of glazing and incorporated the angled head armour used on the F-4, although several G-2s had the vertical type of the G-1. Several Rüstsätze could be fitted, although installing these did not change the designation of the aircraft. Instead the /R suffix referred to the G-2s Rüstzustand or equipment condition of the airframe, which was assigned at the factory, rather than in the field. There were two Rüstzustand planned for G-2s:
* G-2/R1: had one 300 litre drop tank beneath each wing, plus an ETC bomb rack under the fuselage, capable of carrying a 500 kg bomb and an auxiliary undercarriage unit beneath the fuselage.
* G-2/R2: a reconnaissance aircraft with GM-1 and camera equipment.
The rack and internal fuel lines for carrying a 300 litre drop-tank were widely used on G-2s, as were the underwing MG 151/20 cannon gondolas. Several G-2s were fitted with the ETC 500 bomb rack, capable of carrying one 250 kg bomb. The final G-2 production batches built by Erla and Messerschmitt Regensburg were equipped as tropical aircraft (often referred to as G-2 trop), equipped with a sand-filter on the front of the supercharger intake and two small, teardrop shaped metal brackets on the left side of the fuselage, below the cockpit sill. These were used as mounts for specially designed sun umbrellas (called Sonderwerkzeug or Special tool), which were used to shade the cockpit.
167 G-1s were built between February and June 1942, and 1586 G-2s between May 1942 and February 1943; one further G-2 was built in Győr, Hungary, in 1943. Maximum speed of the G-2 was 537 km/h at sea level and 660 km/h at 7,000 m rated altitude with the initial – reduced – 1.3ata rating. Performance of the G-1 was similar, but above rated altitude the GM-1 system could be used for additional performance: 680 km/h could be achieved at 12,000 meters.
In September 1942 the G-4 appeared. It was identical to the G-2 in all respects, including performance, except that the much improved FuG 16 V.H.F. radio set was fitted. Up to July 1943, 1,242 G-4s were produced, and an additional 4 were produced in Győr and WNF factories in the second half of 1943. A pressurized version, G-3 was also produced, being identical to the G-1 in all except its V.H.F. radio set FuG 16. Only 50 were produced between January-February 1943.
In February 1943 the G-6 was introduced with the 13 mm MG 131s, replacing the smaller 7.92 mm MG 17 – externally this resulted in two sizeable blisters over the guns. These bulges reduced speed by nine km/h.
Over 12,000 examples were built well into 1944; the exact number being impossible to ascertain due to numerous variants and rebuilds. The G-5 was identical to the G-6 with pressurized cockpit, and of which 475 examples were built between May 1943 and August 1944. The G-5/AS was the first to be equipped with a DB 605AS engine for high altitude missions. GM-1-boosted G-5 and G-6 variants received the additional designation of /U2.
The G-6/U4 variant was armed with a 30 mm MK 108 cannon mounted as a Motorkanone shooting through the propeller hub instead of the 20 mm MG 151/20. The G-6 was very often seen during 1943 fitted with assembly sets, used to carry bombs or a drop tank, for use as night-fighter, or to increase fire power by adding rockets or extra gondola guns. During 1943, a number of improvements were gradually introduced for the type’s benefit: armoured glass head-rest (“Galland Panzer”) (early 1943), and the introduction of the clear-view “Erla Haube” canopy (autumn 1943) improved visibility, especially to the rear, and a taller tail unit improved stability at high speeds. The introduction of the WGr. 21 cm under-wing mortar/rockets and the 30 mm MK 108 cannon increased firepower. Certain production batches of the Gustav were fitted with aileron Flettner tabs to decrease stick forces at high speeds. Advanced radio/navigational equipment was also introduced. Subsequent Bf 109G versions were basically modified versions of the G-6. 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 Bf 109 G-6. Maximum speed of the G-5/G-6 was 500-510 km/h at sea level, 625-630 km/h at 6,600 m-rated altitude using the restricted 1.3ata boost, and when using the full 1.42ata boost 530 and 640 km/h respectively. Figures are without MW-50 or GM-1 boost.
The G-8 was a dedicated recon version based on the G-6. The G-8 had often only the Motorkanone engine cannon or the cowling machine guns installed and there were several subversions for short or long range recon missions with a wide variety of recon cameras and radios available for use.
The G-14, appearing in mid-1944 was basically a late-war Bf 109 G-6 with the aforementioned improvements standardized, and with MW 50 methanol/water injection increasing output to 1800 hp being a standard fitting. High-altitude models of the G-14 received the DB 605ASM engine and were named G-14/AS. There was increasing tendency to use wood on some less vital parts (e.g. on a taller tailfin/rudder unit, pilot seat or instrument panel) – not because of the shortage of strategic materials like aluminum as often suggested, but as it allowed freeing up metalworking capacity by involving of the woodworking industry of more parts.
The G-10 was an attempt to match the proven Bf 109 G-6/G-14 airframe with the new and more powerful DB 605D engine with minimal disruption of the production lines. Despite what the designation would suggest, it appeared in service after the G-14 and somewhat the K-4 in November 1944. Early production G-10s used fuselages taken from the G-14 production lines, this was probably a source of confusion as many authors still believe many G-10 were based on recycled G-series fuselages. The most recognizable change was the standardized use of the “Erla-Haube” canopy, sometimes referred to (incorrectly) as the “Galland” hood.  This canopy improved the pilot’s view by reducing the number of support struts, which was often criticized before. The G-10 was produced in very substantial numbers, with some 2,600 G-10s produced until the war’s end. 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 bulges covering the breeches of the cowl mounted MG 131, these taking on a more elongated and streamlined form, barely discernible on the upper sides of the cowl panels, as the large engine supercharger required a redesign of the cowling.
A similar varying product was the Bf 109 G-12. This was a two-seat trainer version of the Bf 109 and was rarely armed with anything more than the two cowling machine guns. The space needed for the second cockpit was gained by reducing the internal fuel capacity to only 240 l thus they nearly always used the 300 l drop tank as standard equipment. The G-12 was built using a wide variety of G-series fuselages, many were G-2 based but several were built of rebuilt/repaired G-1, G-4 and G-6.
Bf 109G subtypes and variants
The base subtypes could be equipped with a Rüstsatz add-on standard field kits, in practice this meant hanging on some sort of additional equipment like droptanks, bombs or cannons to standard attachment points, present on all production aircraft. Aircraft could be modified in the factory with Umrüst-bausatz (Umbau) conversion kits or by adding extra equipment, designated as Rüstzustand, to convert standard airframes for special roles – a reconnaissance fighter or bad-weather fighter, for example. Unlike the Rüstsatz field-kits these modifications were permanent.
The Rüstsatz-kits were designated by the letter R and a Roman number. Rüstsatz-kits did not alter the aircraft’s designation, so a Bf 109G-6 with Rüstsatz II (50 kg bombs) remained designated as Bf 109G-6, and not ‘G-6/R2’ – the G-6/R2 was a reconnaissance fighter with MW 50 – as suggested by most of the publications. The Umrüst-bausatz, Umbau. or Rüstzustand were identified with either an /R or /U suffix and an Arab number, i.e. Bf 109 G-10/U4.
Common Rüstsatz kits, Bf 109G
* R I belly bomb rack for 250 kg bomb
* R II belly bomb rack for 4 x 50 kg bombs
* R III belly drop tank (300 l/79 US gallons)
* R IV two 30 mm MK 108 underwing gunpods (not in operational use)
* R VI two 20 mm MG151/20 underwing gunpods
Common Umrüst-Bausatz [Umbau] numbers
* U1 Messerschmitt P6 reversible pitch propeller to be used as air brake, only prototypes
* U2 GM-1 boost, during 1944 several hundred converted to MW-50 boost
* U3 Reconnaissance conversion, in autumn 1943 G-6/U3 adopted as G-8 production variant
* U4 30 mm MK 108 Motorkanone engine-mounted cannon
* G-0 (Pre-production aircraft, powered by a DB 601E engine)
* G-1 (Pressurized fighter, w. GM 1)
o G-1/R2 (Reconnaissance fighter)
o G-1/U2 (High altitude fighter with GM-1)
* G-2 (Light fighter)
o G-2/R1 (Long-range Fighter-bomber or JaboRei- 2x 300 liter underwing drop tanks, one 500 kg bomb under fuselage, extended second tail wheel for large bombs)
o G-2/R2 (Reconnaissance fighter)
o G-2/trop (Tropicalized fighter)
* G-3 (Pressurized fighter, as G-1 with FuG 16 V.H.F. radio; only 50 built)
* G-4 (Fighter)
o G-4/R2 (Reconnaissance fighter)
o G-4/R3 (Long-range Reconnaissance fighter, with 2 x 300 liter underwing droptanks)
o G-4/trop (Tropicalized fighter)
o G-4/U3 (Reconnaissance fighter)
o G-4y (Command fighter)
* G-5 (Pressurized fighter)
o G-5/U2 (High altitude fighter with GM1 boost)
o G-5/U2/R2 (High altitude Reconnaissance fighter with GM1 boost)
o G-5/AS (High altitude fighter with DB605AS)
o G-5y (Command fighter)
* G-6 (Light fighter)
o G-6/R2 (Reconnaissance fighter, with MW 50)
o G-6/R3 (Long-range Reconnaissance fighter, with 2 x 300 liter underwing droptanks)
o G-6/trop (Tropicalized fighter)
o G-6/U2 (Fitted with GM-1)
o G-6/U3 ((Reconnaissance fighter)
o G-6/U4 (MK108 Motorkanone 30 mm engine cannon)
o G-6y (Command fighter)
o G-6/AS (High altitude fighter with DB605AS)
o G-6/ASy (High altitude command fighter)
o G-6N (Night fighter, usually with R6 and FuG 350Z Naxos)
o G-6/U4 N (as G-6N but with 30 mm MK 108 Motorkanone engine cannon)
* G-8 (Reconnaissance fighter as G-6/U3, camera installation behind cockpit)
* G-10 (Light fighter with DB605D/DM/DBM engine)
o G-10/R2 (Bad-weather fighter with PKS 12 autopilot)
o G-10/R5 (Reconnaissance fighter)
o G-10/U4 (Fighter, with MK 108 Motorkanone 30 mm engine cannon)
* G-12 (Two-seat trainer, built from various older G-1 to G-6)
* G-14 (Fighter; standardized late production G-6; MW 50 boost serial standard)
o G-14/AS (High altitude fighter with DB605ASM);
o G-14/ASy (High altitude command fighter);
o G-14y (command fighter);
o G-14/U4 (Fitted with MK 108 30 mm Motorkanone engine cannon)
* G-1/trop (fictional tropicalised variant with 13mm MG 131)
* G-16 (fictional Ground Attack variant, claimed to be based on the G-14 with additional armor)
Erich Hartmann’s Gustavs
We do not have any documentary evidence that Hartmann ever flew a Bf 109K. There are numerous color sideviews of his supposed last aircraft depicted as a K with the dopplewinkle, a wreath on the rudder with “300”, supposedly marking his 300th victory, and then 52 more kill bars.
This sideview has been repeated ad infinitum based on a drawing in one of Karl Ries’ Luftwaffe Camouflage and Markings books. Based on current knowledge this sideview is fiction. While there may be a possibility of him flying a K-4, there is no documentary evidence that he did. Indeed, I./JG 52 flew mostly G-14 and G-10 aircraft in the last months of the war. The list of losses by the gruppe is, at best, rather incomplete. There are some half dozen K-4 losses listed in Fast’s history of the Geschwader, some confirmed by the Quartermaster lists.
The nearest thing to a “last” aircraft flown by Hartmann we have is a photo of him next to a G-10. This aircraft is shown from the supercharger back to about frame 3. We can see that it is the “square panel” type G-10 built by Erla. It could be in the 150xxx or the 490xxx ranges. We can see the famous heart emblem with his wife’s name under the cockpit. Also, we can see the front part of the doppelwinkle. It appears to be either in gray or light green, outlined in white. You can see this photo in B. Barbas’ Aircraft of the Luftwaffe Aces. Other than this, we do not know what any other markings looked like. The time period of the aircraft appears to be in the spring of 1945.
There is always the possibility that someone may show up with a photo of Hartmann’s last aircraft. According to his biography, his log books and photo albums disappeared when the unit surrendered to the Americans in May 1945.
Retrofitted Erla Haube Canopy
Messerschmitt Bf 109 F, G, & K Series: An Illustrated Study by Jochen Prien and Peter Rodeike has some good photographs of erla haube canopies retrofitted to Bf 109G-6’s; these show good detail of the hardware needed for this conversion.
Some G-6, G-8, and virtually all G-14 and G-10 aircraft were fitted with the so-called “Erlahaube” (made by Erla). There was no separate R or U designation for this canopy. Some G-6 and G-5 were retrofitted and the attachment details are slightly different.
Basically, the Erla Haube was built in two versions: The REPLACEMENT TYPE used the existing three-piece hood’s mounting hardware. The PRODUCTION TYPE did away with the old mounting hardware. There are visual cues which easily differentiate which type of Erla Haube you are seeing, but they are too complicated to discuss here. Further, each type of Erla Haube had one or two possible antenna mast attachments.
The Erla Haube was retrofitted to Bf 109G-6’s. It was standard equipment on late-build Bf 109-6’s, and later versions of Bf-109’s (G’s and K’s).