v2.0.0 / 2 of 3 / 01 mar 02 / greg goebel / public domain
* Although the Bf-109E was an excellent aircraft, Willy Messerschmitt felt he could do more with the machine. As a result, the Messerschmitt concern developed the substantially modified and faster "Bf-109F", which would lead to the heavily produced "Bf-109G" and the final German variant of the line, the "Bf-109K". These fighters were mainstays of the defense of the Reich, struggling on against ever-worsening odds as the Allies gained the upper hand.
Given the large numbers of Bf-109s built, it was no surprise that all through its evolution there were side-branches in the form of special modifications and unusual variants that didn't reach full production. This chapter describes the second-generation Bf-109s and the unusual variants.
* Though the Emil was more or less what Willy Messerschmitt had in mind when he designed the Bf-109, he didn't intend to stop there. In early 1940, design work had begun on an evolved version of the Bf-109 to take advantage of improved streamlining and accommodate even more powerful engine types.
The result was the "Bf-109F". The most noticeable difference was a longer and more streamlined cowling ending in a large prop spinner, giving the new variant a cigar-shaped appearance that would be retained in subsequent Messerschmitt Bf-109 variants.
The propeller blades were made 10 centimeters (4 inches) shorter, and wider. The underwing radiators were streamlined, with a ducting system introduced to divert airflow through the wing around them to reduce drag. The bracing struts for the horizontal stabilizer were deleted; the wings were extended and had rounded wingtips; and there were other modifications to the wing, tail, and fuselage. The Bf-109F also featured a semi-retractable tailwheel.
The planned powerplant was the DB-601E, with 1,350 horsepower for take-off. However, since this advanced engine wasn't available in time for initial tests, the first "Bf-109-V21" used the DB-601Aa while the next three prototypes, "Bf-109-V22" through "Bf-109-V24", evaluated the DB-601E.
Manufacturing problems with the DB-601E continued, and so the ten preproduction "Bf-109F-0s" built in late 1940 used the DB-601N engine. Despite the fact that the Bf-109F-0 used the same engine as late production Bf-109s, there was still a definite improvement in performance due to the aerodynamic refinements.
Deliveries of the very similar initial production "Bf-109F-1" variant began in early 1941. The pilots nicknamed the new version the "Frederick". Some of the early F-1s suffered a mysterious loss of control and crashed, and so they were all grounded while Messerschmitt engineers investigated. It turned out that eliminating the bracing struts from the horizontal stabilizer led to resonant vibration of the horizontal tailplane at certain engine RPM levels. Reinforcing plates were added to ensure a solid connection of the horizontal tailplane to the fuselage, and the problem went away.
The Frederick was an impressively streamlined aircraft, and in maturity was fast, with a top speed of 628 KPH (390 MPH). It was to be arguably the best of the Bf-109s, and leveled the balance of air power with the RAF Spitfire Mark V, which had been challenging the Emil.
* Early Bf-109F variants were armed with two MG-17 7.9 millimeter machine guns in the cowling and an MG-FF/M 20 millimeter Motorkanone. While moving back to the engine-mounted gun must have had Messerschmitt engineers worried, they had received feedback that concentrating firepower in the nose provided more focused and effective firepower than could be obtained by placing guns in the wings.
This decision was to prove controversial, since although Luftwaffe aces could make effective use of such armament, other pilots would protest that they required heavier armament and a wider field of fire than needed by the sharp-shooting aces.
The "Bf-109F-2" replaced the MG-FF/M 20 millimeter cannon with an electrically operated MG-151/15 15 millimeter cannon, with higher muzzle velocity; faster rate of fire; and 200 RPG, using belt rather than drum feed. The Bf-109F-2 was also produced in modifications such as the "Bf-109F-2/B" Jabo aircraft, the "Bf-109F-2/Z" high-altitude fighter with GM-1 nitrous oxide boost, and the "Bf-109F-2/Trop" tropicalized fighter.
* When Nazi Germany invaded the Soviet Union on 22 June 1941, the Frederick was in the lead, although many Emils participated as well, and would continue to serve in the Jabo role. On the first day of the attack, a thousand Soviet aircraft were destroyed on the ground, while over 300 were shot down.
Samples of the Bf-109E had been provided to the Soviet Union during the period of Nazi-Soviet "friendship", but the Soviets, possibly blinded by chauvinism and dulled by totalitarian bureaucracy, were dangerously unimpressed by the aircraft. Pitted against obsolete Soviet types like the I-16, Luftwaffe aces flying the Bf-109 began to rack up incredible lists of kills.
On 16 July, Werner Moelders became the first ace to score 101 kills. He was quickly recalled to Germany to train new pilots, only to be killed in a crash while on his way to attend Ernst Udet's funeral.
Other Luftwaffe pilots were to exceed the hundred-kill mark, with a good portion of those kills provided by the Frederick in the Russian campaign. By the end of the war, the top Luftwaffe aces would be Erich Hartmann, with 352 kills, Gerhard Barkhorn, with 301 kills, and Guenther Rall, with 275 kills. Hartmann would be sent to Russian POW camps for ten years after the war, but returned to serve in the post-war Luftwaffe, along with Barkhorn and Rall. Rall would be the first Luftwaffe pilot to solo in the Lockheed F-104 Starfighter.
* The large number of kills claimed by Luftwaffe aces remains somewhat controversial, as they far exceed the kills claimed by aces of all other combat forces. While it is certainly true that all air arms tend to exaggerate their kills, the Luftwaffe was apparently strict in their accounting standards. There were also other reasons, most of them essentially disadvantages to Germany, why some Luftwaffe fighter pilots could score so many kills.
Germany engaged in combat over several fronts for a long period of time. Luftwaffe aces had a relatively soft time of it in Russia at first, engaging large numbers of obsolete Soviet aircraft that were comparatively easy kills. Even later in the war when the Red Air Force had better tactics and fighters like the Yak-3 and La-5, the Soviets tended to trade quantity for quality both in terms of aircraft and pilots, and could still win playing that game.
The numeric imbalance that favored the Red Air Force was increasingly reflected in the West as well, meaning that those Luftwaffe pilots that survived had many opportunities to engage Allied aircraft, while Allied fighter pilots found German aircraft relatively scarce.
The Luftwaffe's limited resources also meant that while Allies could afford to pull their aces out of combat to train the next generation of fighter pilots, the Luftwaffe simply couldn't do it, no matter how much it paid off over the long run.
* In early 1942, the Bf-109F-2 was replaced on the assembly line by the "Bf-109F-3", which was very similar but finally incorporated the DB-601E engine. The definitive "Bf-109F-4" was produced in parallel with the Bf-109F-3 but in far greater numbers. It also featured the DB-610E engine, but replaced the MG-151/15 cannon with an MG-151/20 20 millimeter cannon with 150 RPG, and added improved self-sealing fuel tanks and better cockpit armor protection.
Later Bf-109F-4 production dispensed with the tailplane reinforcements, as
the internal structure of the tailplane had been redesigned to eliminate the
vibration problem. The Bf-109F-4 was also produced in "Bf-109F-4/B" Jabo,
"Bf-109F-4/Z" high-altitude fighter, and "Bf-109F-4/Trop" tropicalized
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spec metric english
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wingspan 9.92 meters 32 feet 6 inches
length 9.05 meters 29 feet
height 2.6 meters 8 feet 6 inches
empty weight 2,590 kilograms 5,270 pounds
loaded weight 3,120 kilograms 6,880 pounds
max speed at altitude 625 KPH 390 MPH / 340 KT
service ceiling 12,000 meters 39,400 feet
range with drop tank 710 kilometers 440 MI / 385 NMI
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Having scored five kills in the Battle of Britain, he rapidly accumulated victories over the desert due to his excellent marksmanship. Marseille died at age 22 on 30 September 1942 when his Bf-109G caught fire and he struck the tailplane while trying to bail out. He would be remembered as the "Star of Africa".
* A total of about 2,200 Fredericks were built. While some sources indicate that there were "Bf-109F-5" through "Bf-109F-8" subvariants, the details are unclear except for the fact that if any were produced, it wasn't in any quantity. There were, however, a number of new subvariant modifications of the Bf-109F-4 built in limited numbers, which became another confusing issue that is addressed in the next section.
There were also a number of experimental conversions of the "Frederick", including fits of the Junkers Jumo 213; pressurized cockpit; wing fences; tricycle landing gear; a "vee" or "butterfly" tail; and even a BMW-801 radial engine.
* The "Bf-109G" was direct follow-on to the Bf-109F. The"Gustav", as it came to be known, was fitted with the still more powerful DB-605-series engine, with was effectively a DB-601 with bored-out cylinders, higher compression, and 1,450 horsepower for takeoff. The new engine was heavier and generated higher torque, requiring airframe reinforcement and changes. Some Gustav variants also featured a pressurized cockpit. Initial deliveries of the Gustav began in early 1942.
By this time, the Bf-109 was clearly past its prime, and the Focke-Wulf 190 would equip Germany's leading fighter squadrons. However, the Reich had lagged in introducing new fighters. There were never enough FW-190s to go around, while development of advanced jet fighters was delayed for technical and bureaucratic reasons until they were, fortunately for the Allies, too few and too late to make a difference.
Uprating the Bf-109 helped plug the gap for a while, but at a price. While the Bf-109 was maneuverable, it had never been light on the controls, and as it became faster it also became more difficult to fly. Its handling on the ground, never good, only kept getting worse. The Gustav was a handful for experienced pilots, and downright dangerous to inexperienced ones.
Ironically, while the Spitfire was upgraded in a similar fashion through the war, the basic Supermarine design proved more adaptable to increased horsepower, armor, firepower, and weight, and later model Spitfires like the Mark IX were more than a match for contemporary Bf-109s.
A Luftwaffe pilot would land his Bf-109G at RAF Manston by mistake later in the war and allow comparison of the Messerschmitt against current Allied types, showing it to have few advantages and many disadvantages relative to the Spitfire Mark IX and XIV, as well as the P-51C Mustang. This Gustav was lost in an accident before it could be tested against a Tempest Mark V.
Despite the limitations of the type, as conditions became increasingly desperate, the Bf-109G would roll off the production line in tremendous numbers, with as many as 24,000 produced by Germany and her allies. Over 14,000 of these were built in 1944 alone.
* Work on 12 preproduction "Bf-109G-0s" began in the summer of 1941, with the last of this batch delivered in October. Due to problems with obtaining the new engines, the preproduction Gustavs were fitted with DB-601E engines. They had the same armament fit as the Bf-109F-4, with twin MG-17 7.9 millimeter guns in the cowling plus an MG 151/20 20 millimeter Motorkanone, and had a pressurized cockpit.
The initial production "Bf-109G-1" began to arrive at Luftwaffe units in March 1942. It was identical to the Bf-109G-0, except that it was fitted with the proper DB-605A-1 or DB-605B-1 engine, with two new small cooling intakes in tandem on each side of the nose, just behind the propeller. The four intakes were added because the DB-605 engine tended to overheat or even catch fire while the aircraft was idling on the runway on hot days. GM-1 nitrous oxide boost was standard.
The Bf-109G-1 was built in a number of modifications, one of the most significant being the "Bf-109G-1/Trop" tropicalized fighter. This modification replaced the MG-17 7.9 millimeter guns in the cowling with MG-131 13 millimeter guns with 300 RPG for additional punch, in case the nose-mounted MG-151/20 jammed.
To accommodate the MG-131s, a pair of bulged fairings were fitted to the cowling just ahead of the cockpit, giving the Bf-109G-1/Trop and similar variants the nickname "Beule (bump)". The fairings did nothing to improve the Bf-109's already poor field of vision while on the ground.
* The topic of Gustav modifications is extremely complicated. Messerschmitt had moved to a process of modification through factory conversion kits, or "Umrust-Bausatz", designated by "U" modification codes, and field upgrade kits, or "Rustsaetze", designated by "R" modification codes. These kits were implemented in late Frederick production, but reached full development with the Bf-109G.
There were many of these kits; sources tend to give the same codes for different kits; and it appears that the same modification code might have different meanings when applied to different subvariants. To complicate matters, a single Gustav might have several kits, or be adapted to different kits over time, but its designation might only reflect one of them. Finally, towards the end of Gustav production many of these modification kits were built in as standard. The issue is very confusing, is unlikely to ever be sorted out with any certainty, and is little more than a headache for anyone who doesn't consider it their life's work.
In general outline, kits included Jabo conversions (codes variously given as "R1" and "R2"); long-range fighters with a centerline rack for a drop tank ("R3"); reconnaissance fighters ("R2", again, and "R4"); and "bomber destroyers". The bomber destroyer fits were particularly interesting and significant, as they were used in numbers to help defend the Reich against Allied bombers.
The first bomber destroyer modification ("R6") involved fit of an MG-151/20 cannon in a gondola under each wing, giving the Bf-109G a total of five guns. This fit adversely affected the aircraft's handling, increasing its weight, reducing its roll rate, and causing roll instability. Such modifications were at a disadvantage in tangling with Allied fighters. The bomber destroyer modification was referred by pilots as the "Kanonboote (Gunboat)".
This armament fit led to kits that provided an MK-108 30 millimeter cannon under each wing instead of the MG-151/20 cannon ("R5"), or fit of 21 centimeter (8.27 inch) WGr-210 "Dodel" rocket launch tubes in place of the underwing cannon ("R21"), for use as a "Polk Zerstoerer (formation breaker)". The big rockets were not very accurate and rarely hit anything, but they were useful for disrupting formations.
There was also a modification kit that exchanged the MG-151/20 Motorkanone for an MK-108 30 millimeter cannon ("U4"), and a similar kit that swapped the MG-151/20 for an MK-103 30 millimeter cannon.
The MK-108 was a short barreled, low-velocity weapon that could fire mine shells. It didn't have much range, but it could be devastating if it scored a hit. Crews called it the "Jackhammer" because of its appearance and the sound of its firing.
The MK-103 was a long barreled weapon and more potent than the MK-108, as it used a full-length round. It could fire tungsten-core armor-piercing rounds for use as an anti-tank weapon or incendiary rounds for air combat. Lack of availability of these heavy cannon meant they were a somewhat unusual weapons fit.
There were specialized kits, such as a radiocompass ("R7"); GM-1 nitrous oxide boost ("U2"); and "MW-50" water-methanol engine boost system ("U3"). This scheme permitted higher combat power by spraying the water-methanol mixture into the cylinders as a cooling measure. The water actually did the cooling, the methanol was added as anti-freeze for winter and high-altitude operation.
Another set of modification kits were implemented to provide a tail assembly with a wooden frame ("U2" again) in order to avoid use of increasingly scarce metals, and then a similar wooden tail assembly with a taller rudder ("U4" again).
* The "Bf-109G-2" was produced in parallel with the Bf-109G-1, and differed in lacking the pressure cabin and GM-1 nitrous oxide boost. The Bf-109G-2 was built in substantially larger numbers than the Bf-109G-1, and was produced in a wide range of modifications.
* Although a "Bf-109G-3" variant was produced, the next version of the Gustav to be introduced was actually the "Bf-109G-4", with initial deliveries in October 1942. It was very similar to the Bf-109G-2, the major difference initially being that the FuG-7A radio was replaced with an FuG-16ZY radio with longer range.
After initial production, the Bf-109G-4 was also fitted with larger mainwheel tires, to handle the greater weight of the Gustav, and to accommodate the bigger tires a bump was built into each wing. This particular bump may have also led to the Gustav being known as the "Beule".
The Bf-109G-3 followed the Bf-109G-4 into production, and was basically a Bf-109G-1 with an FuG-16ZY radio. Some later production featured the wooden tailplane assembly.
* Again, although a "Bf-109G-5" was built, the "Bf-109G-6" was introduced into service first, and in fact was the major Gustav production variant.
The Bf-109G-6 was the first subvariant to feature the twin MG-131 13 millimeter cannon as standard fit, along with the MG-151/20 Motorkanone. It did not have cockpit pressurization. Late Bf-109G-6 production featured items such as a taller rudder and longer tailwheel leg to improve ground handling; radio compass as standard fit; and the new "Galland hood", a bulged canopy to improve visibility.
The Bf-109G-6 was the most heavily produced of the Gustavs, with different
subvariants using different versions of the DB-605. It was sometimes fitted
as a Jabo but particularly used as a bomber destroyer, with the "gunboat"
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spec metric english
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wingspan 9.92 meters 32 feet 6 inches
length 9.03 meters 29 feet 7 inches
height 2.5 meters 8 feet 2 inches
empty weight 2,673 kilograms 5,890 pounds
max loaded weight 3,400 kilograms 7,500 pounds
maximum speed 621 KPH 385 MPH / 335 KT
range with drop tank 1,000 kilometers 620 MI / 540 NMI
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The Bf-109G-5 was identical to the Bf-109G-6 except that it had cockpit pressurization. There was no production "Bf-109G-7". The "Bf-109G-8", introduced in late 1943, was a reconnaissance fighter modification of the Bf-109G-6, with a camera in the rear fuselage, a gun camera in the left wing, and the twin cowling guns deleted.
* Gustavs gunboats were one of the mainstays of the Luftwaffe's defense of the Reich against Allied bombers, and many techniques were used to knock down the attackers. Gustavs were even used to drop fragmentation bombs with time-delay fuzes to break up the formations, but this approach met with little success.
As a night fighter, the Gustav was used in what were referred to as "Wilde Sau (Wild Boar)" tactics, in which day fighters fitted with little or no night-fighting equipment were sent to fly at high altitude over the target area. The target area, far from being blacked-out, would then be illuminated by searchlights and fires to reveal the black silhouettes of RAF bombers below the Wilde Sau fighters.
The Wilde Sau program was the idea of a bomber pilot, Major Hajo Hermann, and many of its warriors were bomber pilots as well. Initial experiments in the tactic were conducted starting in the spring of 1943, but Wilde Sau became the "only game in town" when the RAF starting dropping "window", or strips of aluminum foil designed to jam radar, in July 1943, blinding German air-defense radars and night fighters.
Wilde Sau proved effective in killing RAF bombers, but night flying in aircraft poorly equipped for the task proved dangerous, particularly in bad winter weather. Trying to find someplace to put down could be a problem, and in many cases Wilde Sau pilots simply bailed out of perfectly good aircraft when their options ran out.
Only a few of the Bf-109G-6/N night fighters were built, since by the time they began delivery the Wilde Sau groups were being disbanded, both because of combat attrition and the fact that the Germans had been able to overcome RAF electronics countermeasures to an extent. Had the Bf-109G-6/Ns been available earlier, they might have made a difference since they also had beacon-homing electronics, allowing them to find their way back to base at night.
* The "Bf-109G-10" was basically an attempt to standardize Gustav production, incorporating gear provided in various modification kits for earlier subvariants as standard, and fitted with a DB-605D engine with MW-50 water-methanol injection that gave it a top speed of 690 KPH (429 MPH) at altitude. Armament consisted of an MG-151/20 20 millimeter Motorkanone and twin MG-131 13.7 millimeter guns in the cowling, and the subvariant was fitted with the FuG-16ZY radio. Later production featured the taller tail, longer tailwheel leg, and Galland hood introduced with late-production Bf-109G-6s.
The "Bf-109G-12" was a tandem two-seat trainer, field-modified from the Bf-109G-1 to help the inexperienced pilots the Reich was throwing into battle obtain survival skills from their elders. A trainer subvariant derived from the Emil, to be designated "Bf-109S", had been considered in 1940, but it wasn't until 1942 that the idea was finally implemented using the Gustav. The Bf-109G-12s were all field conversions from other Gustav variants.
The "Bf-109G-14" was the last operational Gustav, with a DB-605AS or DB-605AM engine, three-gun armament, and Galland hood. The new Daimler-Benz engines had improved supercharging, which had been judged to be more effective than either nitrous oxide or water-methanol boost.
The "Bf-109G-16" was similar, but had the earlier DB-605D engine, standard five-gun armament, and a centerline rack. It was apparently intended for the ground attack role. It was not produced in any numbers, if at all.
The Gustav was the main player in "Operation Bodenplatte", in which the Luftwaffe launched a major attack against Allied airfields in France and the Low Countries in hopes of smashing enemy fighter-bombers on the ground. The attack destroyed about 450 Allied aircraft, but resulted in serious losses for the Luftwaffe. The Allies could make good their losses easily, while the Luftwaffe couldn't replace them at all, and most of the pilots who were shot down and survived fell into Allied hands.
* The extraordinary number of modifications of the Gustav proved counterproductive, and led to a desire to come up with a smaller set. The lack of standardization of the aircraft made maintenance and supplying spares a difficult problem. Attempts to solve the problem with later Gustav subvariants such as the Bf-109G-10 didn't prove successful, and so the RLM, in effect, ordered Messerschmitt to try harder.
The result was the "Bf-109K" or "Konrad" series, which was based on the Bf-109G-10. The preproduction "Bf-109K-0" was very much like the final Gustav production subvariants, but featured a raised cowling, a longer prop spinner, a Galland hood, raised vertical tailplane, and fully retractable tailwheel with an extended leg to improve visibility on take-off.
They were fitted with a DB-605B engine with GM-1 nitrous oxide boost as standard. By default they were armed with twin MG-131 guns in the cowling and an MG-151/20 Motorkanone, but they were also evaluated with an MK-108 or MK-103 30 millimeter cannon and twin MG-151/15 15 millimeter cowling guns.
The initial production models were the "Bf-109K-2" and the "Bf-109K-4", with deliveries beginning in October 1944. The Bf-109K-2 was fitted with the DB-605ASC or DB-605DC engine, with GM-1 nitrous oxide boost as standard, and three-gun armament, featuring an MK-108 or MK-103 Motorkanone and twin MG-151/15 cowling guns. The Bf-109K-4 was identical, but featured cockpit pressurization.
The "Bf-109K-6" was a bomber-destroyer derivative of the Bf-109K-4. It differed in that MG-131s were used for the cowling guns instead of MG-151/15s, and two MK-108 guns were fitted in the wings, not in gondolas, for a total armament of three 30 millimeter and two 13.7 millimeter guns. It also had a gun camera. Few were produced as the Reich was falling apart at this time.
There were a few other Konrad variants, but they were produced in very small numbers, if any were actually built at all. The "Bf-109K-8" was a reconnaissance fighter version of the Bf-109K-6, with a camera in the rear fuselage and no cowling guns, the troughs for the barrels being faired over. The "Bf-109K-10" was very similar to the Bf-109K-4, but had MG-131 cowling guns instead of MG-151/15s and a DB-601D engine. The "Bf-109K-14" featured a DB-601L engine with a two-stage supercharger and MW-50 water-methanol injection, plus three-gun armament. It could attain a speed of 725 KPH (450 MPH).
* Something like 34,000 Bf-109s were built to the end of the war, and the type had fought all through the conflict. In the beginning they swept all before them. In the end, there were about 400 Bf-109Gs and 400 Bf-109Ks left to oppose the Allied air fleets, when the Luftwaffe could find gas to fly or pilots to fly them. In the air, they lived the lives of the hunted, fighting on in desperation as Allied fighters roamed the skies in swarms.
One of the last acts of the Bf-109 in combat was "Operation Wehrwulf", where the Messerschmitts were stripped down and used to ram USAAF bombers. A "Rammkommando Elbe" unit was formed under Hajo Hermann, and flew its first and last mission on 7 April 1945, destroying 8 bombers for a loss of 60 fighters.
Adolf Galland's autobiography was titled THE FIRST AND THE LAST. The same title could just as easily be applied to the story of the Bf-109.
* Given the large quantity of Bf-109s built, unsurprisingly there were many odd experiments and unusual variants.
Limited experiments were performed early in the war with a Bf-109E-8 fitted with skis for winter operations, but the skis caused a performance penalty, and regular production Messerschmitts proved to suffer no undue hardship in their use of wheels under winter conditions. The idea went no further.
Another idea that went nowhere were experiments in 1942 with underwing and overwing fuel tanks, fitted to a Bf-109E-4. They did little to interfere with the aircraft's flying characteristics, but centerline drop tanks had proven generally about as effective, so the idea of wing tanks was dropped.
It was revived again a year later in the form of overwing containers that could each carry a parachutist and his gear. This was apparently intended for saboteur drops, and could also be used for medical evacuation. In any case, although the containers, like overwing fuel tanks, proved to hardly impair the Bf-109's performance, mercifully for those who would have had to ride in the thing the idea generated little interest and was forgotten.
Some unusual armament fits were experimentally applied to Gustavs. One involved fit of a pack with twin rearward-firing MG-17 7.9 millimeter machine guns to a reconnaissance fighter as a means of self-defense. Another involved fit of three MG-151/20 cannon gondolas, one under each wing and the third under the centerline.
Fiesler also experimented with a Bf-109G-0 that was refitted with a DB-605A engine and could carry a 500 kilogram (1,100 pound) bomb and dual wing drop tanks. This experimental aircraft was redesignated the "Bf-109G-2/R1". The bomb was so large that it could not clear the ground on takeoff, and so a fixed landing-gear leg was attached to the aircraft just behind the bomb to jack the aircraft's tail up.
The spare leg was ejected by an explosive charge after takeoff and returned to earth by parachute for re-use. The idea was not adopted for operational use. Some sources say the tests went well, but others plausibly claim the aircraft was so overloaded as to be dangerous to fly.
* Another unorthodox idea was to use the Bf-109 as a glider tug. A Bf-109E was experimentally mounted on struts above a DFS-230 troop transport glider, but the idea was not adopted. In a similar scheme, however, the Bf-109 was mounted on top of an unmanned Junkers Ju-88 bomber that was packed with explosives and used as a flying bomb. The FW-190 was also used as a controller aircraft with the Ju-88 and other bombers.
The two aircraft took off together, with the fighter releasing the bomber and guiding it to target. The scheme was known as "Mistel" ("Mistletoe") or "Beethoven", and saw little operational use. It is described in more detail in a companion document, CRUISE MISSILES.
* The Bf-109E-1 was used as the basis for a German naval fighter built by Fiesler, the "Bf-109T", with the "T" standing for "Traeger (Carrier)". The "Toni" was to be used on board the German aircraft carriers GRAF ZEPPELIN, which was launched but never completed for operations, and PETER STRASSER, which was never built.
The Bf-109T featured folding wings with longer span, arrester hook in front of the tailwheel, catapult attachment gear, spoilers on top of the wings, interconnected ailerons and flaps, and full-span leading-edge slats. Ten "Bf-109T-0" preproduction aircraft and 60 "Bf-109T-1" production aircraft were ordered from Fiesler, since Messerschmitt was too heavily committed to existing production orders to do the job themselves.
Fiesler delivered the ten Bf-109T-0s. However, work on the carriers was abandoned and the 60 Bf-109Ts were completed in 1941 as land-based fighters designated the "Bf-109T-2", stripped of such carrier-specific gear as could be removed. They had twin MG-17 7.9 millimeter guns in the cowling and an MG-FF cannon under each wing, and were fitted with a centerline rack for bombs or drop tank.
They had excellent short-field performance and were assigned to short-length fields in Norway, where they provided excellent service. In 1942, they were moved to the German island of Heligoland and remained in service until 1944.
* The "Bf-109H" was a high-altitude fighter ("Hochleichtungsjaeger"), featuring extended wings, a pressurized cockpit, and high-altitude engine fits, built in response to an RLM requirement issued in early 1943.
At first, the Bf-109H was concieved as basically a Frederick with wing inserts to provide extended span for high-altitude operation. The wing inserts had the incidental effect of moving the main landing gear outward, giving the aircraft a wider ground track.
However, this concept was abandoned as it could not meet RLM requirements. Messerschmitt then suggested that their new "Me-209H" fighter, then in development and discussed in more detail later, could do the job. The Me-209H was to have a new DB-628A or DB-603A turbocharged engine for high-altitude operation, but delivery of the Me-209-II was not expected until 1944. As an interim measure, the RLM ordered Messerschmitt to go ahead with the Bf-109H and redesign it for use with the new engines.
A Gustav, designated "Bf-109-V49", had already been fitted with a mockup of the DB-628A as part of the Me-209-II program, and so it was a straightforward step to install an operational DB-628A in another Gustav for Bf-109H flight tests as the "Bf-109-V50". While this aircraft was undergoing trials, a third Gustav was fitted with both the DB-628A and the extended wings.
While Messerschmitt worked on Bf-109H prototypes with the DB-628A engine, they also built of up a batch of "Bf-109H-0" fighters for engineering tests and "Bf-109H-1" fighters for field evaluation, all modified from Fredericks and powered by the more conventional DB-601E engine with GM-1 nitrous oxide boost.
The Bf-109H-1s were evaluated by the Luftwaffe in France in early 1944. The trials went well, except for the fact that the aircraft demonstrated an unhealthy wing flutter in dives. Tests were conducted on some of these aircraft back in Augsburg, and in April 1944 one lost a wing during a dive.
This apparently stalled the program, which was then presently cancelled in favor of the Focke-Wulf Ta-152H. A number of additional H-series subvariants were considered but never reached prototype stage.
* Messerschmitt even considered development of a jet-powered version of the Bf-109, tentatively designated the "Bf-109TL", as a backup plan in case the Messerschmitt Me-262 jet fighter project ran into serious obstacles. The Bf-109TL used a modified Bf-109 fuselage with armament in the nose, and a new wing with two Junkers Jumo-004B turbojets.
The idea was that the Bf-109Tl would be able to leverage off existing production tooling, but to no great surprise as the design evolved, the details of the Bf-109TL diverged from those of standard Bf-109 production enough to ensure that the design provided no real advantages. The idea was abandoned in 1943.
* Another extreme variant was the "Bf-109Z Zwilling (Siamese Twin)", which consisted of two Bf-109F-4 airframes joined together to make a single aircraft. It was conceptually similar to the American P-82 Twin Mustang, except that only the left fuselage had a cockpit. Messerschmitt proposed the idea as a means of providing the Luftwaffe with a long-range Jabo that would leverage off existing Bf-109 production tooling.
Messerschmitt got the go-ahead from the RLM in early 1942. Two variants were planned, including the "Bf-109Z-1" bomber destroyer ("Zerstoerer") with five 30 millimeter guns, and the "Bf-109Z-2" Jabo with twin 30 millimeter cannon and a one-tonne bomb load. Advanced versions with the Junkers Jumo 213 engine were considered.
The prototype was finished in mid-1943, but damaged by Allied bombers before it could fly. Attempts were made to repair it, but then the RLM ordered that the program be abandoned, as interest had moved on to improvements to the Focke-Wulf FW-190 and new jet-powered aircraft.