Background of the Messerschmitt Me 109F
Development of a new airframe began in 1939 and from February 1940, an improved engine called the Daimler-Benz DB 601E was also developed to be coupled with this airframe. Messerschmitt engineers used both the engine and airframe on Bf 109 E-1 cells, the first two prototypes being named V21 (W.Nr 5602) and V22 (W.Nr 1800). They kept the trapeziform wing shape but with a reduced span (61 cm or 2 ft shorter). They in essence "clipped" the tips, which were no longer rounded and the most preeminent feature of the F-type. Also these wings incorporated a modified cooling system. V22 was thoroughly tested and became the testbed for the pre-production DB 601E serie. At first, the clipped wings had negative effect on the handling. So a third prototype, the V23 (W.Nr 5603), used reworked semi-elliptical wingtips. This soon became the new standard for all future Bf 109 airframes. The fourth prototype V24 (W.Nr 5604) still had the clipped wings but with a new "elbow"-like supercharger air-intake. This too, went into production. There was also a deeper oil cooler bath beneath the cowling while aerodynamic studies led the fuselage to be cleaned up and the engine cowling modified.
About the nickname: "Friedrich" was not widely used, to say the least not recognized officially in any documentation. It seemed to have been used "by default". Only "Dora" saw wide use for the "langnase" version of the FW-190, the D-9. The Bf 109D never stick enough to gain it. it was a very different story with the Emil and Gustav, perhaps due to their wide use. The former was also much more popular than the latter, considered too heavy and lacking many amenities of the former ones. Albert Speer came in between and "total war" imposed drastic change in production with simplifications of design and widespread omissions.
Bf 109 F modifications, in detail
The Bf 109 F had many aerodynamic improvements, like the engine cowling smoother and more rounded, enlarged propeller spinner (borrowed from the Me-210) well-blended in the cowling. Underneath the nose was a more streamlined oil cooler radiator, and surrounding fairing, plus a new ejector exhaust arrangement. Late production models would have a metal shield placed over the left hand banks helping chase the fumes away from the supercharger air-intake. The latter was well-rounded, "elbow"-shaped. It helped it protruding in fact more out to gush more cold air for the more powerful engine. The three-blade VDM propeller made in light alloy had an overall reduced diameter (3 m or 9 ft 8.5 in) and the pitch was now electrically set, regulated by a constant-speed unit, but with a manual override backup. In addition the standard 300 liter drop tank made its apparition. For all these changes, the Bf 109 F overall range was now set to 1,700 km (1,060 mi) (previously 660 km (410 miles) and 1,325 km (820 mi) with the drop tank).
The canopy had its forward lower triangular panel replaced by a metal panel, fitted with a port to fire signal flares, well needed in case of a crash. Nevertheless this was a gradual introduction and the F-1s and F-2s essentially never had this modification. Also, the pilot head was better protected b the addition of a two-piece armour plate (same as E-4). It was placed on the hinged portion of the canopy, and on top of that, a bullet-resistant windscreen was optional. More so, from 1942 onwards, pilots had retrofitted on these models a layered light-alloy plate aft of the pilot and fuel tank. To further enhance the pilot's safety, the fuel tank was self-sealing. These were cosmetic changes hardly seen from the exterior.
The tail section was redesigned, the rudder slightly reduced and the fin section took an airfoil shape, creating a sideways lift force swinging the tail slightly to the left, helping its effectiveness, and making the right rudder use on takeoff less useful to counteract torque effects from the engine. The old bracing struts were relocated below and forward, but not removed. The tail-wheel was now retractable and the main undercarriage legs were raked forward by six degrees, which helped greatly ground handling, for the pilot's great relief. It seems at the beginning the wing and tail section broke easily, so much so that JG 2 "Richthofen", Wilhelm Balthasar, was killed when trying the new fighter when his wings broke away. Improvements following during production, with thicker wing skins, reinforced spars and for the tails failure it was shown they occurred because of high-frequency oscillations added to by vibrations from the engine, they resonated incrementally enough to cause a structural failure on the attachment point. Stiffening plates were added both sides, but the entire structure was soon reinforced, and later the entire wing was redesigned. Quasi-elliptical wingtips were adopted with a slight aerodynamic area reduction, but also new leading edge slats, shorter with an increased chord. Removable wingtips also slightly increased the span. They recovered also the plain ailerons of the previous models, for a 2R1 profile with a 14.2% ratio down to 11.35% and a dihedral 6.53°.
Always on the wings, radiators became shallower and moved back on the wing and in general cooling was redesigned, regulated by a thermostat making use of inlet and outlet flaps to procure the most efficient cooling depending on the speed. The new radiator was shallower and wider and fitted with a boundary layer duct for a better airflow. A link was established between the central flap to the lower split flap while the upper one lip position was regulated by an automated thermostatic valve (these valves were delivered as kits to the front). In additions, cutoff valves permitted the the pilot to shut down the wing radiator in case of damage, preserving the remaining coolant. They would eventually became standard on the Bf 109 G and K.
On the Bf 109 F there were two synchronized 7.92 mm (.312 in) MG 17s capable of a rate of fire up to 500 rpg blended inside the engine cowling and the mandatory 20 mm Motorkanone cannon which fired through the propeller hub, probably its most deadly bite. However Adolf Galland criticized it as too light and Major Walter Oesau preferred his Bf 109 E, but on the same time, Werner Mölders saw the 20 mm centerline centerline Motorkanone as a real improvement, and the end, with its teething tail problems fixed, pilots started to lean more favorably towards the F series. For many it appeared as the best-handling so far, Mölders (plane SG+GW) flying one of the first operational Bf 109 F-1 in early October 1940 over UK possibly shoot down no less than eight Hurricanes and four Spitfires in about a week and clearly showed its potential if well-used.
Me109 F Variants
Me109 F-0/F-1/F-2 (?+208+1230=1448)
The pre-production F-0 were recognizable for their rectangular supercharger intake and had the 1,175 PS (1,159 hp, 864 kW) DB 601N engine, mated to a VDM 9-11207 propeller for a top speed of 615 km/h (382 mph). F-0, F-1, F-2 shared this early engine. The first had a centerline 20 mm MG FF/M Motorkanone with 60 rounds and flew in October 1940 (JG 51) over UK. Production of the F1 started in August 1940 and ended in February 1941. They had the same cannon and two 7.92 mm/.312 in MG 17 nose machine guns. The F-2 was armed with the 15 mm Mauser MG 151 cannon (200 rounds) and same nose MGs but some were retrofitted later with the new 20 mm cannon in the field. Production was 1,230 F-2s until August 1941. None were tropicalized although some F-2s received sand filters in the field later (F-2 trop). Another variant (canceled) was the F-2/Z high-altitude fighter fitted with a GM-1 boost, adopted for the F-4.
Me Bf-109F replica in Germany.
Me109 F-3 (15)
On the F-3 and F-4 the engine was now the planned 1,350 PS (1,332 hp, 993 kW) DB 601 E mated with a VDM 9-12010 propeller with broader blades for altitude, the engine being initially restricted but later cleared for service use from February 1942 onwards. This engine oddly used the 87 octane "B-4" aviation fuel while the previous F0/F1/F2 ran on more effective 100 octane "C-3" fuel, perhaps a signe of Germany's dwindling reserves already. The F-3 armament was the same centerline 20 mm cannon of the F-2 and usual pair of 7.92 mm (.312 in) MG 17s on the nose, but only 15 were ever produced. The sereie quickly swapped to the much more successful F-4.
Me109 F-4 (1841)
In addition to the new engine, the F-4 (Frontline June 1941) used the new Motorkanone 20 mm Mauser MG 151/20 (200 rounds), with a total production spanning just a year, between May 1941 and May 1942, and several sub-variants, some using additional 20 mm MG 151/20 wing cannons in faired gondolas. This option became available in field kits as the war progressed for the Me-190G and K in frontline service. These f-4 incorporated many of the above described wngs and tails, cooling later modifications. This was the last production version of the F-type, the rather less known of the whole serie. Indeed, the F-5, F-6 and F-8 were planned but never built as production swapped onto a much better G-type. Variants built were as follows:
Bf-109F evaluated by the South African Air Force
- F-4/R1 (240) with additional 20 mm wings gondola cannons
- F-4/R2 (5) recon version
- F-4/R3 (35) recon version
- F-4/Z (544)high altitude fighter with GM-1 boost
- F-4/Trop (576) Tropicalized version used by the Afrika Korps until 1943.
Messerschmitt Me-109F-4 at the museum Canada Aviation Museum
Messerschmitt Me-109F-2 fighting with the Spanish Division Azul on the Russian in Front 1942. This is an interesting story in itself:
Messerschmitt Me-109F-2 "Trop"
Messerschmitt Me-109F-6 showing some differences
Messerschmitt Me-109F-2 Trop, Afrika Korps main fighters until the end of the campaign in Tunisia in February 1943.
Bf109 F2 Profile Made by Björn Huber
Bf109 F4 in Russia (Bundeswehr)
Bf109 F-2 at the Great Patriotic War Museum
Bf109 F-4 1426 Flight RAF circa 1943
Bf109 F JG 54 Russia
Bf109 F-2 Captured, Duxford 1941
Me 109F in Manching