MESSERSCHMITT BF 109 II

An important attribute of any successful combat aircraft is often said to be its suitability for development.

A capacity for modification or adaptation to take larger and more powerful engines, heavier armament and other operational equipment as such becomes available, without necessitating an extensive re-design of fundamental components and consequent major retooling may well be of incalculable value. Germany’s Messerschmitt Bf 109 single-seat fighter was an excellent example of such development suitability. In its fina1 production models it differed radically from its origina1 prototype of 1935, but the changes were introduced gradually, and thus the flow of new machines to the squadrons was never stemmed.

It has been claimed that the Bf 109 served as a proto-type for international fighter construction; it has been referred to as the progenitor of the high-powered, single-seat, low-wing monoplane fighter. In fact it made its début but a few weeks before Britain’s Hawker Hurricane, and a mere six months before its major wartime antagonist, the Supermarine Spitfire, but it attained service status considerably earlier than either one of its contemporaries, and it was subsequently to claim the distinction of being produced in larger numbers than any other combat aircraft of the Second World War. During its infancy it appeared to lack the hallmark of the thoroughbred, but success came with maturity for, despite severa1 widely publicised shortcomings, the Bf 109 was a highly successful combat aeroplane.

The Bf 109 was conceived in the summer of 1934, when the German Air Ministry issued a requirement far a single-seat interceptor fighter monoplane with which to replace the obsolescent Heinkel He 51 and Arado Ar 65 biplanes then serving the Luftwaffer’s fighter elements. Four manufacturers were awarded prototype development contracts: the Arado Flugzeugwerke produced the Ar 8OV1, the Bayerische Flupzeugwerke produced the Bf 109V1, the Ernst Heinkel A.G. produced the He 112V1, and the Focke-Wulf Flugzeugbau produced the Fw 159Vl. Of these, the Focke-Wulf fighter employed the new and relatively untried Junkers Jumo 210A engine which delivered 610 h.p. for take-off, and the others used the most powerful and reliable engine available at that time, the Rolls-Royce Kestrel V which provided 695 h.p. for take-off.  Trials with the four fighter prototypes, held at Travemfinde during late October 1935, left no doubt as to the superiority of the Bayerische Flugzeugwerke and Ernst Heinkel products. Both machines were low-wing, all-meta1 aircraft with retractable under-carriages, and their performances were closely comparable. 

The He 112Vl possessed the more pleasing contours, and its better streamlined form compensated for its heavier structure. Its undercarriage had a wider track than that of the Bf 109V1, and it did not possess the latter’s enclosed cockpit which was looked upon initially with considerable distrust. Some surprise was, therefore, evinced when the Bf 109 was selected as the winner of the contest, and an order for ten machines placed with the Bayerische Flugzeugwerke. 

Professor Willy Messerschmitt had joined the Bayerische Flugzeugwerke in 1927, and at the end of 1933 was joined by Dipl. Eng. W. Rethel, formerly of Arado. Headed by Messerschmitt and aided by Rethel, the design team strove to achieve optimum performance by designing the smallest possible airframe that could accommodate the most powerful aero engines at that time under development in Germany. The angular lines of the fighter gave it an air of ruthless efficiency, perhaps in keeping with its German origin, and although the wing loading of the prototype was less than 24 lb./sq. ft., the design team anticipated the higher loadings to come, for among the new fighter’s innovations were high-lift devices such as automatic leading-edge slots to give increased aileron control near the stall, large slotted flaps and slotted ailerons which depressed 10” when the flaps were fully lowered. 

The ground angle was steep in order to obtain the steepest practicable incidence and, therefore, the highest lift coefficient when landing. Powered by the 695 h.p. Rolls-Royce Kestrel V the Bf 109V1, bearing the factory number 758 and the civil registration D-IABI, was completed in the summer of 1935 and flown in September. In October, after the initial Right trials had been successfully concluded, the machine was flown to the Rechlin experimenta1 establishment by test pilot Knoetsch. Unfortunately, the undercarriage collapsed during the landing at Rechlin, and the prototype suffered superficial damage. 

Nevertheless, repairs were effected in time for the machine to be flown to Travemunde later that month to participate in the fighter trials. In the meantime work was progressing at Augsburg on further prototypes, and the Bf 109V2 (Werk  Nr.809), registered D-IUDE, was flown in January 1936, being transferred to Travemunde, via Rechlin, on the 21st of that month. This prototype was fitted with the new Junken Jumo 210A engine of 610 h.p. which drove a two-blade, fixed-pitch wooden airscrew. Provision was made for the installation of two 7.9 mm. MG 17 machine-guns in the upper decking of the nose, this armament being proposed for the Bf 109A production model. 

The Bf 109V3 (Werke Nr.810), registered D-IHNY, which followed in June 1936, was generally similar to its predecessor, but it had meanwhile been decided by the German Air Ministry that the armament of two MG 17 guns would be totally inadequate in the light of intelligence reports on the unprecedented armament of eight machine-guns proposed for installation in the Hurricane and Spitfire, and the Bf 109A production model was abandoned in favour of the more heavily armed Bf 109B, no A-series machines being completed. It was proposed that the Bf 109B would initially carry three MG 17 machine-guns, two in the top cowling and synchronized to fire through the airscrew, and the other firing through the airscrew boss. The latter gun would eventually be supplanted by a 20-mm. MG FF (Oerlikon) cannon which would endow the fighter with a longer-ranging armament than that of either of its British contemporaries.   

The fourth prototype, the Bf 109V4, was initially fitted with the trio of MG 17 guns but later conducted the first air firing trials with the 20-mm. MG FF cannon. However, owing to cooling difficulties, the cannon seized after firing a few shells, and it also vibrated badly, so the Bf 109V5 and V6 were completed with the armament of three machine-guns, as was also the production prototype, the Bf 109V7, which flew early in 1937. By this time preparations for quantity production of the Bf 109B fighter had reached an advanced stage at Augsburg, and deliveries of the pre-production Bf 109B-0 for service evaluation were imminent. Flight testing of the prototype had not progressed entirely smoothly. 

The steep landing attitude disconcerted service test pilots, and the fighter had a tendency to drop its port wing just before touch-down. Wing flutter and tail buffeting were experienced, the wing slots malfunctioned, the narrow-track undercarriage failed frequently owing to weak attachment points, and the aircraft tended to swing seriously during take-off and landing. Nevertheless, despite the inauspicious commencement of its career, Germany was determined to impress the world with the capabilities of the reviving German aircraft industry, and from the beginning of 1936 the press department of the German Air Ministry devoted much of its time to eulogizing Germany’s “new wonder fighter”. The fighter had first been seen in public when Oberst Franke, the pilot who was later to be decorated for “sinking” the Ark Royal in 1939, demonstrated the Bf 109Vl in 1936, during the Olympic Games held in Berlin.

 But by 1937 the foreign technical press was becoming increasingly sceptical of the impressive claims made for this fighter, which only a few privileged foreigners had seen. Sensing this, Germany decided that a practical demonstration of the fighter’s capabilities would do much to raise German aviation prestige. Accordingly, it was decided to send a demonstration team equipped with Bf 109 fighters to the International Flying Meeting held at Zurich in July 1937. The team comprised two Bf 109B-ls, a Bf 109B-2, and the Bf 109V13. Led by Major Seidemann, who was later to command the Fliegerkorps Afrika, the three Bf 109Bs won the contest for a circuit of the Alps by military aeroplanes, covering the distance of 228 miles in 57 minutes 7 seconds at an average speed of  233.5 m.p.h. Oberst Franke won the Alpenflug in the Bf 109B-2, covering a circuit of 31.4 miles four times at an average speed of 254.54 m.p.h. He also won the Alpine circuit contest for single military aeroplanes in the Bf 109V13 at an average speed of 241.3 m.p.h., and the dive-and-climb competition, in which he reached 9,840 feet and returned to 1,060 feet in 2 minutes 5.7 seconds.

 The Bf 109Vl3 was a standard B-series airframe adapted to take the 960 h.p. Daimler-Benz DB 600 engine; and to further the considerable prestige gained by the fighter at Zurich, a specially boosted DB 601 engine, delivering 1,650 h.p. for short periods, was fitted in this prototype and the aircraft used by Dr. Hermann Wurster to raise the international speed record for landplanes to 319.39 m.p.h. on November 11, 1937. Eighteen months later Germany was to adopt subterfuge in a successful attempt to gain further acclaim for what was by then Germany’s standard fighter. On Apri1 26, 1939, the world was informed that a specially modified version of the Luftwaffe’s single-seat fighter had raised the world air speed record to 469.22 m.p.h. However, the so-called “Me 09R” record-breaking machine bore no relationship to the Bf 109 fighter other than a common design team, for it was in fact the first prototype of an entirely new design, built specifically for the record attempt and fitted with a special engine giving 2,300 h.p. for short bursts. 

During the spring of 1937 the small pre-production batch of Bf l09B-0 fighters was issued to an experimental unit for service evaluation. This version was powered by the 610 h.p. Jumo 210B engine, but the  first production model, the Bf 109B-1, which followed closely on the heels of the pre-production machines, received the 635 h.p. Jumo 210D, with which it was supplied to the newly formed Richthofen Jagdgeschwader. The Bf 109B-1 attained 292 m.p.h. at 13,100 feet, and attained an altitude of 19,685 feet in 9.8 minutes. Service ceiling was 26,575 feet, and empty and loaded weights were 3,483 lb. and 4,850 lb., respectively. The limitations of the fixed-pitch wooden airscrew necessitated its early replacement by a two-blade variable-pitch metal airscrew, and a licence to manufacture the Hamilton airscrew was acquired from the U.S.A. 

This new airscrew was fitted to the Bf 109B-2, the first production machines of this type having the Jumo 210E engine with two-stage super-charger, but the majority having the Jumo 2l0G of 670 h.p. By now the civil war was raging in Spain, and the Polikarpov-designed I-15 (TsKB-3) and I-16 (TsKB-12) fighters supplied by Russia to the Republican forces outperformed and outgunned the elderly Heinkel He 51 biplanes used by the Condor Legion which was supporting General Franco and the Nationalists. In July 1937 the first and second Staffeln of the Jagd Gruppe J/88 fighting in Spain were re-equipped with some twenty-four Bf 109B fighters, the civil war presenting Germany with an admirable opportunity to test her new fighter under operational conditions. It was here that the ill-founded legend of structural weakness, a legend that was later fostered by Germany’s enemies and was to cling to the fighter throughout its operational career, was first started; an isolated incident of a damaged Bf 109B losing its tail in a high-speed dive being exaggerated to such an extent that it was popularly believed that this fighter would fall apart under high-stress manoeuvres. 

 Although the Bf 109B was still prone to wing flutter and tail buffeting, it proved highly successful. While largely used for bomber escort duties and for occasional fighter sweeps over Republican airfields, Oberstleutnant Harder built up a considerable score of  “kills” in his Bf 109B, and the machine proved to be an effective weapon against the Russian fighters. However, one major shortcoming was revealed: inadequate armament. The three 7.9.-mm. MG 17 machine-guns provided insufficient rage and weight of tie, and several B-mode1 airframes were fitted with a 20-mm. MG FF cannon in place of the centrally-mounted MG 17. But this cannon was unreliable and still prone to seizing after only a few shots had been fired. This and severe vibration while firing prevented its widespread use. At Augsburg extensive armament tests were undertaken. 

The Bf 109V8 was fitted with two wing-mounted MG 17 machineguns, in addition to the two mounted in the engine cowling, although these aggravated the flutter problem unti1 the ailerons were balanced and the wing leading edge stiffened. The next prototype, the Bf 109V9, had two 20-mm. MG FF cannon installed in the wings. These machines served as prototypes for the production C-series, which were essentially similar to the B-mode1 apart from their armament. The pre-production Bf 109C-0 and the initial production Bf 109C-1 both carried four MG 17 machineguns, and the Bf 109C-2 subtype had a further MG 17 firing through the airscrew hub. 

The experimental Bf 109C-4 had four MG 17 guns and a single 20-mm. MG FF cannon, but this version was not placed in service. In August 1938 twelve Bf 109C-1 fighters arrived in Spain to re-equip the third Staffel of J/88 which was subsequently commanded by Werner Molders, who became the top-scoring German fighter pilot in Spain. While work was progressing on the improvement of the fighter’s armament, parallel experiments were being conducted with a view to improving performance. An early 960 h.p. Daimler-Benz DB 600 engine was installed in a standard B-series airframe to form the Bf 109VlO. Two further prototypes, the V11 and V12, were fitted with the production type DB 600A, resulting in a substantial, improvement in performance, a maximum speed of 323 m.p.h. being attained, and service ceiling being boosted to 31,170 feet. With this engine a new sub-type, the Bf 109D, entered production late in 1937, the pre-production Bf 109D-0 fighters employing converted B-model airframes and carrying an MG 17 machinegun in each wing as first introduced on the Bf 109C. 

In addition, a single engine-mounted MG FF cannon was carried. A small production batch of Bf 109D-1 fighters followed to equip one Gruppe, but the availability of the redesigned DB 601 engine, incorporating direct fuel injection and improved supercharging capacity, had led to the abandonment of further production of the DB 600 and, in consequence, the Bf 109D in favour of the Bf 109E with the later engine, and ten of the Bf 109Ds were sold to Switzerland and three to Hungary. The Bf 109E was the first true mass-production model of the basic design, and by the end of 1939 it had replaced all previous models in first line service with the Luftwaffe, and thirteen Gruppen, each of forty aircraft, were operating with this type when the Second World War commenced. This fighter was referred to throughout the war years as the “Me 109”, but the contraction “Bf” far Bayerische Flugzeugwerke was the prefix used for all versions of the 109 by officia1 German handbooks and documents, including those produced after the company was reconstituted as the Messerchmitt A.G. 

The first true prototype for the E-series was the Bf 109V14, which was powered by the 1,100 h.p. DB 601A engine and was flown during the early summer of 1938. This carried an armament of two wing-mounted MG FF cannon and two MG 17 machineguns in the engine cowling. The Bf 109V15 differed in having an engine-mounted MG FF cannon and no wing guns. The pre-production Bf 109E-0 fighters appeared late in 1938, and both these and the initial Bf 109E-1 fighters carried an armament of four MG 17 machine-guns as the MG FF cannon was still considered to be inadequately developed for operational use. The Bf 109E-1 and E-l/B fighter-bomber, the later carrying four 50 kg. bombs or one 250 kg. bomb, were standard equipment with the Luftwaffe by the time Germany went to war, and by the end of 1939 production had been transferred from the Augsburg factory to the new Regensburg plants (Regensburg-Priifening and Regensburg-Obertraubling).

 The Erla plant at Leipzig-Mockau, the Ago factory at Oschersleben, the Fieseler plant at Kassel, the Arado factory at Warnemunde, and the W.N.F. factories at Delitzsch and Wiener-Neustadt were being integrated in the mass-production programme for this fighter, and a total of 1,540 machines had been produced. By standards appertaining at that time, the Bf 109E was a very good fighter. It handled well and possessed excellent low-speed control response and “feel”, although above 300 m.p.h. the controls became extremely heavy, and the ailerons in particular became almost immovable at around 400 m.p.h., making  rolling virtually impossible. It lacked the manoeuvrability of the Spitfire, nor did it possess the British fighter’s turning circle, but its angle of climb was extremely good, being developed at low airspeeds. 

The Spitfire enjoyed a slight margin in speed, but both the climb rate and ceiling of the Bf 109E were superior, and the German fighter was definitely the better above 20,000 feet. In a vertical dive the Spitfire could not stay with the Bf 109E; but light though the rudder was at low and medium speeds, the absence of a cockpit operated rudder trim was a serious fault because the rudder became very heavy in a dive, and then reversed trim, resulting in considerable pilot fatigue. The direct injection pumps of the DB 601 engine had an advantage over the carburettors of the Merlin, and the engine did not cut out or splutter under negative “g”. The stall was gentle with no tendency to spin, ample warning of its approach being given through aileron vibration and tail buffeting. With the slotted flaps lowered to 20°, the take-off run was remarkably short and, the main wheels being positioned well forward of the centre of gravity, fierce braking was permitted immediately on touch-down, resulting in a short landing run and fast taxiing. 

However, the tendency to swing on take-off and landing, which had first manifested itself during tests with the early prototypes, continued to plague the Bf 109E and contributed substantially to the Luftwaffe’s high accident rate, some 1,500 Bf 109 fighters being lost between the beginning of the war and the autumn of 1941 in accidents caused by unintentional swings. Only after the tailwheel had been fitted with a locking device, which operated when the throttle was fully opened, did the tendency to swing lessen.  The Bf 109E1 carried two 7.9-mm. MG 17 machine-guns in the engine cowling and one MG 17 or 20-mm. MG FF cannon in each wing. With the latter guns installed the weight of fire was 290 lb./min. Empty and loaded weights were 4,360 lb. and 5,400 lb., respectively and, with a wing area of 174 sq. ft., the wing loading was 32.1 lb/sq. ft. 

Overall dimensions included a span of 32 ft. 4 1/2 in., a length of 28 ft. 4 in., and a height of 7 ft. 5 1/2 in. with tail down. Maximum speed was 354 m.p.h. at 12,300 feet, and at economica1 cruising speed (62.5 per cent rated power) and allowing for climbing at full throttle to operating altitude after taking-off, the range was 412 miles at 16,400 feet. Initial climb rate was 3,100 ft./min., service ceiling was 36,000 feet, and the absolute ceiling was 37,500 feet. The Bf 109E-l/B fighter-bomber utilized the “Revi” gun-sight as a bomb-sight, and the angle of dive for bombing was graphically shown by a red line painted on either side of the cockpit canopy at 45° to the horizon to enable the pilot to put the machine into the correct diving angle. For high-altitude bombing the diving speed was 403 m.p.h., and for bombing from a low altitude the recommended diving speed was 373 m.p.h. 

The maximum permissible diving speed was 446 m.p.h. The main sub-type of the E-series, the Bf 109E-3, entered production late in 1939. This model differed from its production predecessor in having provision for one 20-mm. MG FF cannon firing through the airscrew boss, in addition to the paired guns above the engine and in the wings. However, the engine-mounted cannon was still unreliable and was seldom used operationally. More Bf 109E-3 fighters were built than any other model of the E-series, and by the beginning of 1940 the production rate had attained some 150 machines per month, a total of 1,868 being completed during 1940. Of these, 304 machines were exported to foreign air force, including Bulgaria (19), Japan (2), Hungary (40), Rumania (69), Slovakia (16), Switzerland (80), Russia (5), and Yugoslavia (73). By the turn of the year the Bf 109E-4 had supplanted the E-3. This model reverted to the twin engine-mounted MG 17 guns and pair of MG FF cannon, but the latter were of an improved type.

 The E-4/B was a fighter-bomber variant. The year 1941 saw the introduction of numerous improvements: the Bf 109E-VN was fitted with the 1,200 h.p. DB 601N engine which was chiefly distinguished for its petrol injection system and the automatically-controlled hydraulic coupling to the supercharger drive. This version was later employed primarily in North Africa; the Bf 109E-5 was a special short-range reconnaissance model with reduced armament (two MG 17) and a camera in place of the wireless, and the E-6 was similar but employed the DB 601N engine. The Bf 109E/7 was normally a fighter equipped to carry an external jettisonable tank, but some of this sub-series were later converted for low-flying attack roles in North Africa, extra armour being bolted beneath the engine and coolant radiators, and designated Bf 109E-7/ U2, the suffix “U” indicating “modification”. The Bf 109E-7/Z was fitted with a special bi-fuel “power boosting” system known as GM-1, the E-8 was a further fighter variant in which all the progressive improvements incorporated in earlier models became standard, and the final sub-type of the E-series, the Bf 109E-9, was a reconnaissance aircraft carrying an RB 50130 camera and a 66 Imperial gallons drop-tank. In 1940, when work was progressing rapidly on Germany’s first aircraft Carrier, the Graf Zeppelin, a shipboard fighter variant of the Bf 109E-3 was produced by the Fieseler-Werke. Known as the Bf 109T (the ”T” indicating “Trager” or “Carrier”), this fighter possessed increased wing area, and spoilers fitted on the wing upper surfaces at one-third chord to steepen the gliding angle and reduce the landing run. 

The outer wing panels were folded manually, and an arrester hook was fitted. Only ten fighters of this type were completed by Fieseler, and these were subsequently reconverted to standard Bf 109E-3 configuration. More extensive aerodynamic improvements made necessary to take full advantage of the increased power available from later Daimler-Benz engines were initiated in the spring of 1940. A standard Bf 109 E airframe (Werke Nr.5604) was fitted with a 1,200 h.p. DB 601E.1 engine housed in an entirely redesigned, symmetrical cowling. The supercharger air intake was redesigned and positioned further out  from the engine cowling to increase the ram effect, the airscrew spinner was enlarged, and the diameter of the airscrew reduced by some six inches. 

Shallower under wing radiators were fitted, incorporating boundary layer bypasses, and the braced tail plane was replaced by a cantilever structure. This experimental machine was flown for the first time on July 10, 1940, at Augsburg-Haunstetten, and subsequently served as the first prototype for the F-series fighters. The Bf 109F embodied all the modifications included on the experimental machine and also an extensively re-designed wing which was tested on two further E-airframes. The new wing featured rounded tips and slightly increased span. 

The slotted ailerons were replaced by Frise-type surfaces, and plain flaps of reduced area replaced the slotted flaps that had been standard on all previous models. In addition, a retractable tail wheel was fitted. The first pre-production Bf 109F-0 fighters were delivered to Luftwaffe test centres for evaluation late in 1940. These were powered by the DB 601N engine which also powered the majority of the Bf 109F-1 production batches, and an armament of two MG 17 machine-guns and one MG FF cannon was carried. The first Bf 109F1 fighters were delivered to operational units in January 1941, but in February three early production machines were lost in temporarily inexplicable circumstances. In each case the pilot announced over the R/T that his engine was vibrating violently, and immediately thereafter his aircraft dived out of control, the pilot having no time to bail out. A few weeks later a fourth accident occurred when the tail assembly of a Bf 109F-1 broke off in midair. 

Upon examination it was discovered that all the screws on the tail assembly/fuselage joint had been torn out. This could only have been caused by the tremendous vibrations for which the engine could not be held responsible as it was found to have suffered damage only in the crash. Suspicion then fell on the tail spar since the rivets between the ribs and the elevators were all loose, missing or broken. Prolonged investigations ascertained that when the bracing struts of the Bf 109E tail assembly were omitted on the Bf 109F and stronger but less ribbing used, the proportion of the rigidity to the strength of the member was altered. The result was that the tailplane had a frequency of oscillation which, at certain r.p.m., was overlapped by the engine, and the resultant sympathetic vibrations tore out the tail spars.

Within a few months of the service debut of the Bf 109F-1, in July 1941 a well-known German fighter pilot, Peter Pingel, was forced down over Britain, his Bf 109F-1 being virtually intact. This aircraft was subsequently repaired, enabling British test pilots to ascertain its handing characteristics and performance. The Bf 109F-2 differed from the initial production model in having the engine-mounted MG FF replaced by a 15-mm. MG 151 which substantially increased firepower because of its higher velocity and better trajectory. However, there were conflicting opinions among the leading German fighter pilots concerning the armament of the Bf 109F. Adolf Galland considered the reduced number of guns to be a retrogressive step, while Werner Molders favoured this light armament. Later, the Bf 109F4/Rl was to appear with a 20-mm. MG 151 cannon mounted in a gondola under each wing; but while this improved the fighter’s effectiveness as a bomber destroyer, it adversely affected the machine’s powers of manoeuvre and reduced its potency in fighter-versus-fighter combat.

The Bf 109F2/Z had GM-l power-boosting equipment, and the F-2/Trop was a tropicalized version for use in North Africa. Both the F-l and F-2 production models were intended to have the DB 601E engine of 1,300 h.p., but delivery delays had necessitated the installation of the DB 60lN, and it was not until the Bf 109F.3 appeared on the production lines early in  1942 that the DB 60lE war installed. With this engine the Bf 109F.3 could attain a maximum speed of 390 m.p.h. at 22,000 feet. Normal cruising range was 440 miles at 310 m.p.h. at 16,500 feet, and service ceiling was 37,000 feet. Empty and loaded weights were 4,330 lb. and 6,054 lb. respectively, and wing loading had risen to 34.8 lb./sq. ft. The Bf 109F-4 had the engine-mounted 15-mm. MG 151 cannon replaced by a 20-mm. MG 151, and the F-4/B and F-4/Trop were fighter bomber and tropicalized versions respectively.  

The Bf 109F-4/Rl could have a GM-I power boosting  system in place of the additional 20-mm. cannon under wing, and it was intended to fit four RZ 65 air-to-air or air-to-ground rocket missile on under-wing racks, but this armament was never perfected for operational use. The Bf 109F-5 was used primarily for long-range reconnaissance duties, carrying a 66 Imperial gallon drop-tank, and the F-6 was another reconnaissance variant which, generally unarmed, had an RB 5O/30, RB 20/30 or RB 75/30 camera in place of the radio. Several F-series airframes were utilized for experimental purposes. One Bf 109F-1 was fitted with boundary layer fences for comparison purposes with the leading-edge slots; one was fitted with an elongated wing for high-altitude trials, another had a vee-type or “butterfly” tail assembly, two others had single and twin nose wheels, while yet another had the DB 601N engine replaced by a BMW 801 radial for comparison with the Fw 190. The later experiment was unsuccessful as the slim fuselage married to the bulky engine resulted in extreme turbulence in the area of the tail assembly. 

Another interesting experiment was the Bf 109Z, the marriage of two standard Bf 109F-1 fuselages and port and starboard wings with a new centre wing section and tail plane which joined the two fuselages to form “Siamese twins”. This was built to test the possibilities of the proposed Me 609, but the prototype was never flown. A total of 2.628 Bf 109E and F fighters was produced in 1941, and of this total some 60 per cent was produced by the Erla plant at Leipzig-Mockau (683) and the W.N.F. factories at Delitzsch and Wiener-Neustadt (836). During the spring and summer of 1942 the assembly lines began to switch to the production of the Bf 109G, deliveries of which commenced in the late summer of 1942 and which was appearing on all war fronts by the end of that year. With the phasing out of the F-series, the basic Bf 109 design might be considered to have passed the peak of its development, for with the introduction of the G-series the constant operational demands for increased fire power and additional equipment brought with them a serious deterioration in the fighter’s flying characteristics.  

The Bf 109G could not be flown in a landing circuit with Raps and undercarriage down other than at full throttle, and experienced German operational pilots have described its landing characteristics as “malicious”. Nevertheless, some 70 per cent of all the Bf 109 fighters produced during the war years were of the G-series. The most important change denoted by the introduction of the Bf l09G was the installation of the more powerful DB 605A engine in which the cylinder block had been redesigned to obtain the maximum possible bore with the existing cylinder centres, the permissible r.p.m. increased, and numerous other changes made in comparison with the DB 601. 

These changes resulted in an output of 1,475 h.p. at 2,800 r.p.m. at sea level, and 1,355 h.p. at 18,700 feet. However, this engine was not available for installation in the twelve pre-production Bf 109G-0 fighters which retained the DB 601E engine of the preceding production model. The Bf 109G-0 was fitted with a pressurized cockpit, a feature which was becoming increasingly necessary in view of the altitudes to which air combat had by that time risen, and this was also fitted in the first production model, the Bf l09G-1, which was powered by the DB 605A-l engine with GM 1 power boost. The Bf 109G-1, which was dubbed “Gustav” by its pilots, carried a single engine-mounted 20-mm. MG 151 cannon and two MG 17 machineguns mounted over the engine. The latter 7.9-mm. guns were replaced by 13-mm. MG 131 machine-guns in the tropicalized Bf 109Gl/Trop, the installation necessitating the provision of fairings over the gun breeches.

The G-2 was generally similar but had no pressure cabin. It was used primarily in the fighter-reconnaissance role, and the service test group at Guyan-court, France, experimented with a ventral gun pack in which two rear-firing MG 17 machineguns were fitted. The G-3 was similar to the G-1 but fitted with FuG 16Z radio in place of the earlier FuG7A, while the G-4 was an unpressurized version of the G-3. The Bf 109G-5 received the DB 605D engine which had a supercharger of increased diameter and a methanol/water injection system. The two agents were contained in a jettisonable tank under the fuselage and fed to the engine in times of emergency.

When injected into the cylinders with the 100-octane fuel, the methanol and water increased the amount of combustible mixture per unit volume of the cylinder, the increase in thermal efficiency temporarily boosting power to 1,800 h.p. at sea-level. The G-5/R2 was fitted with a taller fin and rudder assembly and lengthened tail wheel leg in a fresh attempt to cure the swerve which still characterized takeoff and landing. The new tail assembly was made of wood in an attempt to conserve light metals. The Bf 109G-6, which could be fitted with several alternative versions of the DB 605, carried a 30-mm. MK 108 cannon firing through the airscrew boss, two 13-mm. MG 131 machine-guns above the engine, and two 20-mm. MG 151 cannon in under wing gondola. 

The MK 108 used explosive ammunition, and its muzzle velocity was only 1,760 ft./ min., but it proved to be an effective anti-bomber weapon. In the G-6/U4 version the MG 151 cannon were replaced by two MK 108s. The Bf 109G-6/U4N was an improvised night fighter to use “Wilde Sau” tactics. This variant was fitted with “Naxos Z” warning and homing receivers with a range of thirty miles. The rotating antenna was installed aft of the cockpit, but the radar scope merely indicated direction and not distance. Two Staffeln were equipped with this improvised night-fighter and operated briefly in the Cologne area, but the majority of these machines were destroyed in landing accidents owing to the inadequate night-flying experience of their pilots. The Bf 109G-6/Rl was a fighter-bomber conversion of the basic sub-type, and the G-6/R2 carried two WG 21 rocket tubes in place of the under-wing gun gondola. 

The WG 21 missiles were of 21-cm. calibre, and fighters so equipped were mostly used by the J.G.I. and J.G.26 “Schlageter” units, but the missiles reduced maximum speed by some 25 m.p.h. and disrupted the airflow over the elevators, and only limited success was attained. The Bf 109G-7 was a proposed version in which all the successive modifications to the G-6 version became standard, but this type did not enter production. The G-8 reverted to the old tail assembly and was a fast reconnaissance model fitted with an RB 12.5/7 or RB 32/7 camera. The engine-mounted MK 108 was removed. 

The fastest sub-type of the G-series was the Bf l09G-10 which, powered by the DB 605D engine and aided by GM 1, attained 428 mph. at 24,250 feet. Climb to 20.000 feet was effected in 6 minutes, and range was 350 miles. No wing guns were carried, and the engine-mounted MK 108 was optional. The Bf 109G-10/U4 carried two additional MK 108 cannon with eighty rounds per gun in a belly tray, but this was subsequently replaced by a non-jettisonable long-range tank known as the “Immer-Behalterer”.

The G-10/R2 and R6 received the new tail assembly, the elongated tail wheel leg, FuG 25a equipment for friend-foe identification, and a modified cockpit canopy known as the “Galland hood”. Several Bf 109G-1 airframes had an additional seat installed and were redesignated Bf 109G-12 operational trainers. The pupil and instructor were seated in tandem, and the side windows of the rear cockpit were bulged in order to improve the instructor’s view.

The last of all the G-series fighters to attain operational status was the Bf 109G-14. This model was generally similar to the G-6 and could be fitted with the DB 605A, AM, AS, ASB, ASM or D engine, and armament comprised two MG 131 machine-guns and one 20 mm. MG 151 in the fuselage, and provision was made for the fitting of two MG 151 cannon under wing. One 250 kg. bomb or two WG 21 rockets could be carried, and the “Galland hood” was standard. The G-14/Trop was a tropicalized version, and the G-14/R2 received the new wooden tail unit first fitted to the G-5/R2 but retained the short tail-wheel leg. The final production G-series aircraft, the Bf 109G16, did not reach operations. It was generally similar to the G-14 but retained the old-type cockpit hood, and was heavily armoured for the close support role.

Despite the advent of the very much superior Focke-Wulf Fw 190 fighter, production of the now elderly Bf 109 was progressively increased. Total production for 1942 amounted to 2,664 machines. This total was not very much greater than that for the previous year, a fact accounted for by the phasing out of the Bf 109F in favour of the G-series and the retooling of the Ago factory at Oschersleben, the Fieseler factory at Kassel, and the Arado factory at Warnemunde for other aircraft types, but in 1943 production rose to 6,418 aircraft. In that year the Industria Aeronautica Romana (I.A.R.) factory at Brasov, in Rumania, the Hungarian Waggonwerke D.F.A.G. at Budapest, and a Messerschmitt controlled plant at Gyor in Hungary had completed retooling and commenced deliveries of the Bf 109G. 

Although the various complexes of factories controlled by the Messerschmitt A.G. were increasingly heavily bombed in 1944, production figures still increased in leaps and bounds, the unprecedented total of 14,212 machines being delivered in that year. Of these, 6,318 were produced by Messerschmitt’s Regensburg factories which reached their production peak in October 1944 with the delivery of 755 aircraft. Small numbers of Bf 109G fighters were exported in 1943-44, this type being delivered to the air force of Bulgaria (145), Finland (70), Japan (21), Rumania (70), Slovakia (15), Spain (25) and Hungary (59). Surprisingly, in the few months of 1945, before Germany’s collapse, when communications had been disrupted and few factories above the surface of the ground were intact, the German aircraft industry still succeeded in producing 2,969 Bf 109 fighters, of which 1,074 were produced at Regensburg. In 1943, development of a specialized high-altitude version of the basic Bf 109F/G series was commenced.

A small number of pre-production aircraft, designated Bf 109H-0, were converted from standard Bf 109F airframes by the insertion of additional wing sections which increased span by 6 ft. 6 in. and the attachment of a new, long-span tailplane which was reinforced by stout struts. The Bf 109H-0 was powered by the DB 601E engine, but the production Bf l09H-1 had the DB 605A with GM-1 boost and was used in the summer of 1944 by the service test group at Guyan-court. Intended for fighter-reconnaissance duties, the Bf l09H-1 was able to reach an altitude of approximately 47,000 feet, and attained a maximum speed of 466 m.p.h. Armament comprised two 7.9-mm. MG 17 machine-guns and one 30-mm. MK 108, and it was proposed to insta11 two 13-mm. MG 131 guns in the wings. However, the long-span wing fluttered severely in dives, and further development was abandoned in favour of the Focke-Wulf Ta 152H. At one time several developments of the basic type were proposed, including the Bf 109H-2 which was to have had a Jumo 213E “power egg” and pressure cabin, and the Bf 109H-5 with the DB 605L engine.

In the early autumn of 1944 the first aircraft of the K-series made their appearance with service test groups. The pre-production machines were designated Bf 109K-0 and were essentially similar to the Bf 109G but incorporated minor structural differences and standardized on the DB 605D engine with MW 50 power boost. Three sub-types were produced, the Bf 109K-4 and K-6, powered by the DB 605ASCM/DCM, and the K-14 powered by DB 605L. The Bf109K-4 carried an armament of two 15-mm. MG 151 guns over the engine and one engine-mounted MK 108 or MK 103. A pressure cabin was fitted and the “Galland hood” was adopted as standard. Maximum speed at sea-leve1 was 377 m.p.h., and at 19,685 feet was 452 m.p.h. Service ceiling was 41,000 feet, and climb to 16,400 feet took 3 minutes, and to 32,800 feet took 6.7 minutes. Range at a loaded weight of 6,834 lb. was 356 miles, and maximum take-off weight was 7,400 lb. The Bf 109K-6 differed primarily in its armament which comprised two 13-mm. MG 131 guns over the engine, an engine-mounted 30-mm, MK 108 or MK 103, and two MK 103 cannon under-slung on the wing. Maximum take-off weight was 7,920 lb., and maximum speed was 440 m.p.h. at 19,700 feet. The Bf 109K-14 carried two MG 131 and one MK 108, and attained 455 m.p.h. at 37,750 feet. The two earlier versions were entering service at the end of the war, but the Bf l09K-14 had not attained operational status.

The Bf 109L was basically a G-series airframe in which the fuselage section had been increased to merge with a Junkers Jumo 213E “power egg”. The wing span was increased to 43 ft. 9 in. and the area to 236 sq. it. Theoretical maximum speed was 476 m.p.h. at 35,000 feet, hut development was never completed. Another version under development at the end of the war was the Bf 109S. This development was being undertaken by Caudron-Renault in Paris, and a prototype, the Bf 109V24, was tested in the Chalais-Meudon wind tunnel. The Bf 109s was to have incorporated a system of air discharge over the wing to improve control at low forward speeds, and was nearing completion at the time of France’s liberation.

The Messerschmitt Bf 109 was a standard Luftwaffe single-seat fighter for nearly a decade. No exact figures are available for the tota1 number of fighters of this type produced, but it is believed that more than 33,000 were built between 1936 and the end of the Second World War, representing more than sixty per cent of al1 the single-engined fighters produced by Germany during that period. Manufacture of the Bf 109 continued in Czechoslovakia and Spain after World War II, endowing Professor Messerschmitt’s fighter with a record for production longevity. Having fought on every front upon which the Luftwaffe was engaged, and having been produced in water numbers than any other combat type, the Messerschmitt Bf 109 probably ranks second only to the Supermarine Spitfire as one of the true “immortals” of the Second World War.