One of the most famous aircraft of all time, the Messerschmitt Bf 109 was to be built in larger numbers than any other fighter aircraft, with a production run in excess of 30,000, its advanced design and high performance providing the benchmark by which other types were measured for much of its existence. A low-wing cantilever monoplane with a flush-riveted skin, the Bf 109 showed considerable ingenuity in design as Willy Messerschmitt had gone to great lengths to keep its size and weight to the absolute minimum. The first Bf 109 (D-IABI) was flown on 28 May 1935 by Flugkapitän Hans Knoetzsch and was powered by a Rolls-Royce Kestrel V of 695 hp. Subsequent machines were fitted with a 610 hp Junkers Jumo 210 12-cylinder, inverted-vee, liquid-cooled engine, but in 1937 the first test flights were carried out with the new Daimler Benz DB 600A engine of 960 hp, which endowed exceptional performance with a top speed of 323 mph. In late 1937 a specially boosted DB 601 engine of 1650 hp propelled Bf 109 V13 to a new world speed record for landplanes of 379 mph.
After the early Jumo-powered Bf 109B/C, the first main variant was the Bf 109E or Emil, which was fitted with a 1100 hp DB 601A. Although based on the earlier DB 600, it featured direct fuel injection instead of a carburettor, and improved supercharging. The first Emils were delivered to JG 132 at Dusseldorf in December 1938 and by September 1939 the Luftwaffe had taken delivery of over 1000 Bf 109s, including the early variants used in the Spanish Civil War. Experience during the latter conflict and in the initial stages of the Second World War had shown the Bf 109 to be a supreme fighter, but its true test would come when it encountered the Hurricanes and Spitfires of the RAF. Clashes began in earnest after the German invasion of the Low Countries on 10 May 1940, with French-based Hurricanes hopelessly outnumbered by large numbers of Bf 109Es and Bf 110 twin-engined long-range fighters. RAF Fighter Command’s Spitfires, which had been kept well away from the defensive actions over France, were finally drawn into the air battles that were soon raging in the skies over Dunkirk, but the main confrontation was yet to come.
RAF Fighter Command already knew much about their principal adversary as a result of the Bf 109E-3 captured intact by the French in late 1939. Following the comparative assessment with the Hurricane made by pilots of No. 1 Squadron (see Chapter 1), the aircraft was flown to the UK for evaluation and a series of handling trials were carried out at Farnborough in May/June 1940. The aircraft was flown by three RAE pilots, who all commented on the cramped, narrow cockpit and lack of headroom. The location of the rudder pedals also meant that the pilot sat in a slightly reclined attitude, which was not particularly comfortable. The positioning of the controls was good, in particular the elevator trim and flap controls on the pilot’s left and the throttle control, which was not gated and was described as being ‘marvellously simple’ in operation.
Several aspects of the cockpit design were unusual to British pilots; toe instead of stick-operated brakes and the lack of a blind flying panel being two of the more notable omissions. The absence of an Artificial Horizon was particularly felt when flying in cloud. There was also no klaxon to warn the pilot should he forget to lower the undercarriage prior to landing. The hood was hinged on the starboard side and could not be opened in flight, although sliding windows were fitted on each side. However, these were difficult to open at high speed and cockpit noise (already high) increased appreciably. In an emergency, a jettison lever released the whole hood for the pilot to bale out.
When on the ground the forward view was extremely poor due to the aircraft’s steep tail-down attitude, but in the air it was no worse than in a Hurricane or Spitfire. The cramped seating position in the Bf 109 did, however, make it difficult to clear the area downwards and to the rear. A direct vision panel was provided, which proved to be of great value when flying in bad visibility. It was draught-free at all speeds, which meant that a Bf 109 could fly faster in such conditions than a Spitfire, whose pilot had to resort to opening the hood and peering out around the windscreen, a task that could only be done at relatively slow speed due to the slipstream. The direct vision panel was also of use when landing, due to the aircraft’s high nose position on touchdown.
On take-off with 20 degrees of flap set, the throttle could be opened quickly without fear of the engine choking, thanks to the fuel-injected DB 601’s smooth response. Initially, the control column was held forward, but the tail came up quickly and it could then be eased back. Pilots soon became accustomed to holding the aircraft down on take-off, until they were sure that flying speed had been attained, as the left wing was liable to drop if pulled off too soon. The take-off run was extremely short and the initial rate of climb was significantly better than the early Spitfires equipped with two-pitch propellers (this advantage was largely nullified with the introduction of constant-speed propellers on later Spitfires). The best approach speed was 90 mph IAS with the flaps and undercarriage down and as the glide was quite steep, the view ahead was reasonably good. Landing required a greater degree of skill than either the Hurricane or Spitfire, as the aircraft had to be rotated through a large angle to adopt the correct three-point attitude. If a wheeled landing was attempted, there was a tendency for the left wing to drop. As CG was well behind the main wheels, full braking could be used immediately after touchdown without risk of the tail lifting.
The stall speed with the flaps and undercarriage up was 75 mph IAS. When gliding at 1.2 × stall speed, a forward or backward movement of the control column produced a very slowly damped pitching oscillation of long period when the stick was released, before the aircraft eventually settled to its trimmed speed. About 1 in of backward stick movement, requiring hardly any force, was required to bring about a stall. The slots opened at about 110 mph IAS and as they did so the ailerons snatched slightly and there was slight aileron vibration. If both the ailerons and rudder were held fixed, the left wing dropped suddenly through about 10 degrees at 83 mph IAS and the aircraft went into a gentle left-hand spiral. Aileron could be used to lift the wing. If this was attempted, with the rudder fixed, the aircraft became laterally unsteady and there was some aileron buffet which increased as speed was reduced. Below 77 mph IAS the aircraft could not be controlled by aileron alone.
If the rudder was used to raise the wing (ailerons fixed) the lateral oscillations could not be checked at speeds below 81 mph IAS. Control could be retained down to the stall speed of 75 mph IAS by vigorous use of aileron and rudder. By the time stall speed was reached, the aileron buffet was very marked and the aircraft was very unsteady laterally. If the stick was pulled further back at the stall, the ailerons and rudder were still slightly effective, but the aileron buffeting and lateral unsteadiness was of such violent proportions that a sustained stalled glide was impossible. At no time did the aircraft show any tendency to spin.
With the flaps and undercarriage down the stall speed was 61 mph IAS. Any fore or aft movement of the stick at 1.2 × stall speed led to a quickly damped pitching oscillation when the stick was released, and the aircraft was far more stable than in the clean configuration. No aileron snatching occurred when the slots opened at about 90 mph IAS and there was very little stall warning. If both the ailerons and rudder were held fixed, the aircraft maintained a straight path down to the stall when the left wing dropped suddenly through about 10 degrees followed by the nose, with a left-hand spiral once again the result. There was complete control until the stall was reached, but neither the rudder nor ailerons were effective at the stall, and the dropped wing could not be raised until speed had increased. As in the previous case, there was no risk of a spin developing.
Aileron control when flying at approach speed was very good; there was a positive feel and the response was quick. This was in marked contrast with the Spitfire, in which aileron control lightened with loss of speed to the point where feel was lost. As speed was gained, the ailerons of the Bf 109E tended to become heavier, but the response remained excellent up to 200 mph IAS. Above this speed the ailerons became unpleasantly heavy and were nearly immovable above 400 mph IAS. A pilot applying all his strength at this speed could only generate about one-fifth aileron movement, or about the same as a Spitfire in similar circumstances. Unlike Allied fighters, the Bf 109 did not have a rudder trimmer and during high-speed dives the pilot had to exert considerable pressure on the left rudder to keep the aircraft straight. This characteristic, together with heavy aileron control, tended to limit evasive manoeuvres in dives to right turns only.
Following the initial handling trials, a number of mock combats were carried out with a Spitfire I at around 6000 ft. The Bf 109 had a considerably heavier wing loading (32.2 lb/sq.ft compared with 24.8 lb/sq.ft) and so it was no great surprise to discover that the Spitfire could easily stay with its German rival during sustained turns up to 220 mph IAS. The Bf 109 would stall if the turn was tightened to generate more than 4 g, the leading edge slats tending to open shortly before this figure was reached, causing some aileron snatch and loss of sighting view. If the control column was pulled back further, a shuddering would be felt. The aircraft would then either come out of the turn or drop its wing even more, oscillating in pitch and roll and rapidly losing height. The stall itself was fairly benign and the aircraft made no attempt to flick into a spin.
Paradoxically, there were a number of occasions when the Bf 109 was able to stay with a Spitfire in a turn, despite its supposed inferiority in this respect. This was due to concerns on the part of the Spitfire pilot as regards his aircraft’s handling as it approached its limit. With its extremely light elevator control, a high-speed stall was a distinct possibility, in which case it was likely to flick and enter a spin. Many pilots were wary of this and as a result did not utilise the Spitfire’s turn performance fully.
During dives, it was found that the Spitfire could match the Bf 109 (more so if it had a constant-speed propeller), but the latter could initiate a diving manoeuvre much quicker due to its fuel-injected engine. Pilots of the Bf 109 found they could push over straight into a dive without their motors cutting, as was the case with both the Hurricane and Spitfire and their carburettor-equipped Merlins. The best climb speed of the Bf 109 was lower than the Spitfire, but its climbing angle was much steeper, which gave it an advantage in offensive and defensive manoeuvring in the vertical plane.
A good evasive manoeuvre for a Spitfire pilot was a half roll and dive, thus taking advantage of his aircraft’s light elevators to bring about a rapid recovery. A Bf 109 pilot trying to follow this was faced with his aircraft building up speed quickly in the dive, followed by a decrease in elevator effectiveness as the control forces rapidly built up. Considerable height could be lost in this manoeuvre and if carried out at too low a level, could result in the aircraft flying into the ground.
Aerobatics were also flown but the Bf 109 did not find favour. As looping manoeuvres had to be started at around 280 mph IAS, the heavy elevator control at this speed was not ideal and as the speed diminished at the top of the loop, the slats could sometimes pop out, the resulting aileron snatch affecting directional control. During rolls below 250 mph IAS, there was a tendency for the nose to drop in the final stages, involving considerable backward movement of the control column. Upward rolls also suffered, due to the heaviness of the elevator control and resultant difficulty in setting up the required vertical axis.
The maximum speed of the Bf 109E was recorded as 355 mph TAS at 16,400 ft with the radiators closed and 330 mph TAS with the radiators open. A height of 23,000 ft was reached in just over ten minutes and the absolute ceiling was 32,000 ft. The trials were carried out at a take-off weight of 5580 lb, which included full internal fuel tanks and a full war load.
Trials were also carried out by A&AEE, the findings being broadly in agreement with RAE Farnborough as the following extracts from their report indicate.
All controls in level flight are light, quick in response and effective up to a speed of 250 mph IAS after which they become extremely heavy. This is particularly the case with the elevator which is out of harmony with the other controls to start with, becoming noticeably heavier, and in the dive almost immovable. It is to be particularly stressed that the controls are pleasantly light at all speeds up to 250 mph IAS and they appear to tighten up very suddenly so that at high speed they are practically immovable. Experienced pilots state that in the event of an attack from behind by a 109, the attack can easily be broken off by the attacked by pulling up quickly from a dive. The 109 cannot follow due to the heaviness of its controls.
Loops – It is impossible to execute a loop in the normal manner due to the heaviness and ineffectiveness of the elevator. If a normal loop is attempted, the aeroplane flicks on the top of the loop. The only way in which a loop can be done is by winding the tail trim back. Even then great care must be taken to ensure that the aeroplane does not flick out of the loop at the top.
Slow-rolls – It is very easy to slow-roll the aeroplane at speeds up to 250 mph IAS but at higher speeds the controls are so heavy that difficulty is experienced. A great deal of rudder has to be used in the rolls and this is unusual in the modern fighter. Very tight rolls can be executed at speeds up to 190 mph IAS. Slight snatching of the aileron is noticeable in rolls at speeds of 120–140 mph IAS.
Half roll off a loop – This manoeuvre is difficult for the same reason as given above. When rolling off to the left the aeroplane has to be checked as it tends to flick out in the opposite direction. To the right the difficulty is overcoming a tendency towards a high speed stall. Provided the control column is eased forward, however, the manoeuvre can be completed successfully.
Summary of flying qualities – General reports on the handling of the aeroplane which were received before the arrival of the aeroplane itself led one to believe that numerous faults existed, but these have been found to be untrue. The aeroplane is pleasant to fly at speeds up to 250 mph IAS, the only objection being the lack of space in the cockpit. This objection is a very real one in the case of a large pilot. At speeds in excess of 250 mph IAS the controls suddenly become very heavy and at 400 mph IAS recovery from a dive is difficult because of the heaviness of the elevator. This heaviness of the elevator makes all manoeuvres in the looping plane above 250 mph IAS difficult, including steep climbing turns. No difference was experienced between climbing turns to the right or left. In general the flying qualities of the aeroplane are inferior to both the Spitfire and Hurricane at all speeds and in all conditions of flight. It does not possess the control which allows good quality flying and this is particularly noticeable in aerobatics.
After use by A&AEE and RAE, the Bf 109E (by now carrying the serial number AE479) was flown by AFDU at Northolt and Duxford and was delivered to the USA in 1942.
In many respects the testing that was carried out at Boscombe Down and Farnborough in 1940 tended to compare the Bf 109 and Spitfire as pure flying machines and the respective reports left the reader in no doubt as to which was considered to be the better machine. Unfortunately, the Bf 109 and Spitfire were both weapons of war and delicate handling characteristics or the purity of an aerobatic manoeuvre would count for nothing in an aerial dogfight. Despite certain similarities in design and performance, the Bf 109 and Spitfire were poles apart. With its lightly loaded wing, the Spitfire was always going to come out on top in a turning fight, whereas the excellent vertical penetration of the Bf 109 meant that it was ideally suited to dive and zoom tactics, a situation that was aided by its fuel-injected Daimler Benz DB 601 engine. Despite such inconsistencies, the outcome of many air battles still depended to a large extent on which pilot saw the other first.
The Messerschmitt Bf 109 was heavily developed throughout the Second World War, the next major variant after the Emil being the Bf 109F or Friedrich. Although early variants were powered by the DB 601N of 1200 hp, the more powerful DB 601E of 1300 hp was fitted from the Bf 109F-3. The airframe was tidied up considerably with revised supercharger and radiator intakes, rounded wing tips, a cantilever tailplane and a fully retractable tailwheel. The Bf 109F showed its superiority over the Spitfire V as a high-altitude fighter in 1941/42, but was supplanted from the summer of 1942 by the Bf 109G or Gustav, which was basically an F-series airframe fitted with the new DB 605A of 1475 hp. The Gustav was virtually identical to the Bf 109F, the only distinguishing features being two small intakes behind the propeller spinner and the deletion of the two triangular-shaped windows on the fuselage sides below the windscreen.
A number of captured examples of the Bf 109G were flown by British testing establishments, including AFDS at Wittering. The aircraft tested was Bf 109G-6/U-2 Werke Nummer 412951, which also carried the serial number TP814. It was powered by a DB 605A-1, which developed 1550 hp at 22,000 ft and was armed with two MG 131 machine-guns mounted above the engine, a single MG 151/20 cannon firing through the propeller hub and two MG 151/20 cannon carried in underwing gondolas. Fittings were provided under the fuselage to enable an overload fuel tank to be carried or a 250 kg bomb. The all-up weight with a full war load was approximately 7488 lb, giving a wing loading of 43.6 lb/sq.ft.
The cockpit was as narrow and cramped as ever, but the instrument panel had been tidied up with superfluous instruments and controls having been removed. The usual flying instruments were installed, but a combined Artificial Horizon and Turn and Bank Indicator was of particular note. The engine instruments were standard, with the permissible limits marked on the dials. Two wheels were positioned on the left-hand side of the pilot’s seat, the outer wheel controlling the operation of the flaps and the inner wheel the tailplane incidence. A gauge was provided for the latter, the position of the flaps being indicated by lines painted on the port wing flap. Operating switches for the undercarriage were also located on the left side of the cockpit.
Engine revs and boost were interconnected and were operated under normal conditions by the throttle control. Provision was made, however, for independent operation of engine rpm in an emergency situation, by a switch installed below the throttle quadrant. Revs could then be controlled by a two-way pivot switch attached to the top of the throttle lever, but this system had only to be used in the event of the Constant Speed Unit failing.
The view forwards and downwards out of the Bf 109G was even worse than on earlier aircraft due to the bulges on each side of the forward fuselage that covered the ammunition feed chutes for the MG 131 machine-guns. Willy Messerschmitt had paid particular attention to streamlining in the design of the Bf 109. Great difficulty was therefore experienced in accommodating the subsequent need for more guns of a heavier calibre. Not only did the various bulges and appendages restrict the pilot’s view, they also tended to increase drag and reduce overall performance.
When manoeuvring on the ground, the Bf 109G was not particularly nose heavy. The brakes were positive, but the tailwheel did not caster easily and so sharp turns were difficult. Because of the high nose and poor forward visibility, extreme care had to be taken when taxying in the vicinity of other aircraft or obstructions. One disturbing aspect noted with TP814, was its tendency to disgorge exhaust fumes into the cockpit when taxying at low revs.
Unless taking off directly into wind, the aircraft showed a strong inclination to weathercock and as a result the throttle had to be opened slowly. Once in the air, the rudder was noted as being fairly heavy, but not uncomfortably so. As with earlier aircraft, there was no rudder trimming and it was necessary to apply right rudder for take-off and left rudder at high speeds. With increase in speed, the ailerons became increasingly stiff and were especially so at speeds in excess of 350 mph IAS. At speeds below 180 mph IAS, it was noted that the ailerons were not particularly positive and as the stall was approached they were almost non-effective. The elevators also became increasingly difficult to operate as speed increased and this was accentuated above 350 mph IAS by the fact that the elevator trimmer control was practically impossible to operate.
A number of tactical comparisons were carried out, including an evaluation of TP814 and a Spitfire LF.IX with a low-altitude rated Merlin 66. The two aircraft were compared for speed and all-round manoeuvrability at heights up to 25,000 ft. With the Spitfire being flown at 18 lb/sq.in boost it held a slight advantage up to 16,000 ft, but was then overtaken by the Bf 109 from 16–20,000 ft. Above this height, the Spitfire was again the faster by about 7 mph. At 25 lb/sq.in boost the Spitfire was 25 mph faster up to 15,000 ft, becoming 7 mph faster above that height.
During sustained climbs, the Spitfire was found to be superior to the Bf 109G at all heights. It had a particular advantage below 13,000 ft using 18 lb/sq.in boost and was, naturally, even more in the ascendant when using 25 lb/sq.in boost. When both aircraft were pulled up into a climb following a dive, the performance was almost identical, but when climbing speed was reached the Spitfire began to slowly pull away. The Spitfire also had the advantage in rate of roll and turn performance, in which it was greatly superior, but the Bf 109G could leave its rival without any difficulty during dives.
The Bf 109G was also compared with a fully operational Spitfire XIV powered by a 2050-hp Griffon 65 using 18 lb/sq.ft boost. The Spitfire proved to be superior in every aspect of performance, being approximately 25 mph faster at all heights up to 16,000 ft. As this was the rated altitude of the Bf 109G, the performance gap shrank to 10 mph at this height. However, it then increased progressively with altitude, the Spitfire being 50 mph faster by the time that 30,000 ft had been reached. In terms of climb performance, there was little to choose between the two aircraft at the Messerschmitt’s best operating height of 16,000 ft, but at all other heights the Spitfire had a pronounced superiority in rate of climb. The Bf 109G’s former ascendancy over the Spitfire in dive performance was largely nullified against the Mark XIV, as although it held a slight initial advantage, this was lost as soon as speed was increased above 380 mph IAS.
The Spitfire’s famed turn performance was still apparent, although the use of the Griffon engine, which turned in the opposite direction to the Merlin, meant that the advantage was more marked when turning to the right. The rate of roll of the Mark XIV was, like its predecessors, superior at all speeds.
Before TP814 could be compared with a Tempest V, it suffered a fate similar to many other Bf 109s when it was wrecked as a result of a take-off accident. Its pilot on that fateful day was Len Thorne, but it was later ascertained that the crash had occurred as a result of undercarriage failure as he recalls:
During the Autumn of 1944 a Bf 109G was allocated to AFDU under the number TP814. Most of the flying was carried out by other unit pilots; my experience was limited to five flights during October and November, but as an aircraft, I didn’t enjoy it. I found the cockpit cramped and, with the up-and-over canopy, very claustrophobic. Great care had to be taken when taking off and landing due to the Gustav’s inclination to swing and ground-loop at the slightest provocation. When taking off at Wittering on the grass on 22 November 1944 I managed to avoid such trouble, but could do nothing when the port oleo support strut fractured as the aircraft was about to unstick. The port wing tip struck the ground and TP814 carried out a complete cartwheel. Once again I was quite lucky as I was doing about 120 mph at the time. Luckily it came to rest the right way up but was rather badly bent. As other Bf 109s were available it was decided not to undertake repairs.
A trial had, in fact, already taken place between a Tempest V and another Bf 109G of 1426 (Enemy Aircraft) Flight. This trial had shown that the Hawker fighter using 9 lb/sq.in boost had a speed advantage of 40–50 mph at heights below 20,000 ft, but this superiority rapidly diminished above this height. Generally, the climb of the Bf 109G was superior to that of the Tempest at all heights, but this advantage was not pronounced at heights below 5000 ft. When both aircraft commenced a dive at the same speed and were then put into a climbing attitude, the Tempest was slightly superior and this could be maintained if the Tempest possessed an initial speed advantage and was able to keep its speed above 250 mph IAS.
Comparative dives between the two aircraft showed that the Tempest would pull away from the Bf 109G. Although the gap did not widen markedly in the early stages of the dive, in a prolonged descent the Tempest was greatly superior. At speeds below 350 mph IAS there was practically nothing to choose between the two aircraft as regards rate of roll, but when this speed was exceeded it was found that a Tempest pilot could out-manoeuvre a Bf 109G by banking quickly and changing direction. Turn performance was evenly matched, the Tempest being marginally the better machine.
The Bf 109 remained in production until the end of the war and was the subject of further development. The fastest of all the Gustav variants was the Bf 109G-10, which achieved a top speed of 428 mph powered by a DB 605G engine with MW-50 water-methanol injection. The last production series was the Bf 109K, which entered service towards the end of 1944. The final variant to see service (albeit in very small numbers) was the Bf 109K-14, which was powered by a DB 605L of 1475 hp with MW-50 and was armed with two MG 131 machine-guns and a single MK 108 cannon. Had the war continued, it is likely that further advanced variants of the Bf 109 would have been produced, including the L-series, which would have featured a 1750 hp Junkers Jumo 213E engine in place of the DB 605. The estimated top speed of the Bf 109L was 474 mph, approximately 20–25 mph faster than the Spitfire F.21.