Genesis and competition Throughout the 1930s, the air forces of many major military powers were engaged in a transition from
biplane to
monoplane designs. Most concentrated on the single-engined
fighter aircraft, but the problem of range arose. The
Ministry of Aviation (RLM, for
Reichsluftfahrtministerium), at the encouragement of
Hermann Göring, issued a request for a new multipurpose fighter called the
Kampfzerstörer (battle destroyer) with long range and an internal bomb bay. This request called for a twin-engined, three-seat, all-metal monoplane that was armed with cannon and a
bomb bay. Of the seven companies approached, only Bayerische Flugzeugwerke (which later became
Messerschmitt),
Focke-Wulf, and
Henschel responded to the request. The Focke-Wulf design, the
Focke-Wulf Fw 57, had a wingspan of 25.6 m (84 ft) and was powered by a pair of
DB 600 engines. It was armed with two
20 mm MG FF cannons in the nose, while a third was positioned in a dorsal
turret. The Fw 57 V1 flew in 1936, but its performance was poor and the machine crashed. The
Henschel Hs 124 was similar in construction layout to the Fw 57, equipped with two
Jumo 210C for the V1. The V2 used the
BMW 132Dc
radial engines generating 870 PS compared with the 640 PS Jumo. The armament consisted of a single rearward-firing 7.92 mm (.312 in)
MG 15 machine gun and a single forward-firing 20 mm MG FF cannon. Bayerische Flugzeugwerke omitted the internal bomb load requirement from the RLM directive to increase the armament element of the RLM's specification. The Bf 110 proved to be far superior to its rivals in providing the speed, range, and firepower to meet its role requirements. Accordingly, Bayerische Flugzeugwerke's submission bested Focke-Wulf, Henschel, and
Arado, and thus the firm was given the funds to build several
prototype aircraft. By the end of 1935, the Bf 110 had evolved into an all-metal,
low-wing cantilever monoplane of semi
monocoque design featuring twin
vertical stabilizers and powered by two DB 600A engines. The design was also fitted with
Handley-Page wing
slots (actually,
leading-edge slats). The initial deliveries of the Bf 110 encountered several delays with their DB 600 engines, which forced Bayerische Flugzeugwerke to install
Junkers Jumo 210B engines, leaving the Bf 110 seriously underpowered and able to reach a top speed of only 431 km/h (268 mph). The armament of the A-0 units was also limited to four nose-mounted 7.92 mm (.312 in)
MG 17 machine guns. Even without delivery of the DB 600 engines, Bayerische Flugzeugwerke began assembly of the Bf 110 in mid-1937. As the DB 600 engines continued to have problems, Bayerische Flugzeugwerke was forced to keep on using Jumo motors, the 210G, which supplied 515 kW (700 PS) each (versus the 471 kW/640 PS supplied by the 210B). Three versions of the Bf 110B were built, the B-1, which had four 7.92 mm (.312 in) MG 17 machine guns and two 20 mm MG FF cannons, the B-2
reconnaissance version, which had a camera in place of the
cannons and the B-3, which was used as a
trainer, with the cannons replaced by extra radio equipment. The major identifier of the -A and -B-series Bf 110s was the very large "mouth" bath
radiators located under each engine. In late 1938, the DB 601 B-1 engines became available in quantity, and thus were promptly adopted on the Bf 110C. In the adoption of this engine, the design teams opted to remove the radiators under the engine nacelles and replace them with water/glycol radiators for the C-series airframes, placing them under the wing just outboard of each nacelle, otherwise similar in installation, appearance and function to those on the Bf 109E. With the DB 601 engine, the Bf 110's maximum speed increased to with a range around . A compact oil cooler and air scoop remained under each engine nacelle for the remainder of the Bf 110's production run. First conceived in the latter half of 1939, the Bf 110D featured a series of modifications and improvements to increase its range. The initial D-series version, the Bf 110D-0 was designed to add a large, streamlined, 1,050-litre (277 U.S. gallon) ventral fuel tank built under the fuselage, which required a substantially sized, conformal
streamlined ventral fuselage fairing extending from halfway back under the nose to the rear of the cockpit glazing, inspiring the nickname
Dackelbauch (
dachshund's belly). The D-1 was also set up to accept a pair of
fin-equipped 900-litre (238 U.S. gallon) drop tanks, one under each wing, increasing the total fuel capacity to 4,120 litres (1,088 U.S. gallons). The substantial added drag of the early "dachshund's belly" ventral fuselage tank in test flights mandated its omission from production D-1s, although they were still prepared to mount an improved, more streamlined, version. D-1s so equipped were known as D-1/R1, whereas the D-1/R2 was equipped with two 900-litre drop tanks and a droppable 85-litre oil tank. Later D-2 and D-3 versions retained the twin underwing 900-litre drop tank capability, using multipurpose ordnance racks capable of holding either drop tanks or carrying bombs.
Later production variants The production of the Bf 110 was put on a low priority in 1941 in expectation of its replacement by the Me 210. During this time, two versions of the Bf 110 were developed, the E and F models. The E was designed as a fighter bomber (
Zerstörer Jabo), able to carry four 50 kg (110 lb) ETC 50 racks under the wing, along with the centreline ETC 500
bomb rack. The first E, the Bf 110 E-1 was originally powered by the DB 601B engine, but shifted to the DB 601P as they became available in quantity. In total, 856 Bf 110E models were built between August 1940 and January 1942. The E models also had upgraded
armour and some
fuselage upgrades to support the added weight. Most pilots of the Bf 110E considered the aircraft slow and unresponsive, with one former Bf 110 pilot commenting the E was "rigged and a total dog." The Bf 110F featured the new DB 601F engines, which produced 993 kW/1,350 PS (almost double the power the original Jumo engines provided), which allowed for upgraded armour, strengthening, and increased weight with no loss in performance. Three common versions of the F model existed. Pilots typically felt the Bf 110F to be the best of the Bf 110 line, being fully aerobatic and in some respects smoother to fly than the Bf 109, though not as fast. Eventually, 512 Bf 110F models were completed between December 1941 and December 1942, when production gave way to the Bf 110G.
Bf 110G production details with
Matratze UHF radar antennas for
FuG 202/212 use Although the
Me 210 entered service in mid-1941, it was plagued with problems and was withdrawn from service for further development. In the wake of the failure of the Me 210, the Bf 110G was designed. The G model was fitted with
DB 605B engines, producing 1,085 kW (1,475 PS) at their
Notleistung (war emergency) top-level setting, and 997 kW (1,355 PS) at 5.8 km (19,000 ft) altitude. The Bf 110G also had upgraded nose armament, and underwent some changes which improved the aerodynamics of the aircraft. The rear cockpit access was moved forward from the transversely hinged, "tilt-open" rearmost canopy glazing to a side/top hinged opening section of the main canopy, opening to port, with a new rearmost framed glazing section fixed in place. No Bf 110 G-1 existed, so the Bf 110 G-2 became the baseline Bf 110G. A large number of
Rüstsätze field conversion packs were available, making the G subtype the most versatile production version of the Bf 110. The initial batch of six preseries production G-0 aircraft built in June 1942 were followed by 797 G-2, 172 G-3 and 2,293 of the night fighter-dedicated, three-seater G-4 models; built between December 1942 and April 1945. Pilots reported the Bf 110G to be a "mixed bag" in the air, in part due to all changes between the G and F series. The Bf 110G was considered a superior gun platform with excellent all-around visibility, and considered, until the advent of the
Heinkel He 219, to be one of the best night fighters flown by the
Luftwaffe.
Armament The Bf 110's main strength was its ability to mount unusually powerful air-to-air weaponry. Early versions had four 7.92 mm (.312 in)
MG 17 machine guns in the upper nose and two 20 mm
MG FF/M cannons fitted in the lower part of the nose. Later versions replaced the MG FF/M with the more powerful 20 mm
MG 151/20 cannons and many G-series aircraft, especially those which served in the bomber-destroyer role, had two 30 mm (1.18 in)
MK 108 cannons fitted instead of the MG 17. The defensive armament initially consisted of a single, flexibly mounted 7.92 mm (.312 in)
MG 15 machine gun. Late F-series and prototype G-series were upgraded to a 7.92 mm (.312 in)
MG 81 machine gun with a higher rate of fire, and the G-series was equipped with the twin-barreled
MG 81Z. Many G-series night fighters were retrofitted or factory-built with the
Schräge Musik off-bore gun system, which fired upward at an oblique angle for shooting down bombers while passing underneath; it was frequently equipped with two 20 mm MG FF/M, but field installations of the 20 mm MG 151/20 or 30 mm (1.18 in) MK 108 cannons were also used. The
Schräge Musik weapons were typically mounted immediately in front of the rear
cockpit. The Bf 110 G-2/R1 was also capable of employing armament such as the
Bordkanone-series 37 mm (1.46 in)
BK 3,7 autofed cannon, mounted in a conformal ventral
gun pod under the fuselage. Becoming active around July 1942, the Bf 110F-4 was the first version to be designed specifically as a night fighter. It was something of a stop-gap measure, though armed with four 7.92mm/ 0.31 in machine guns and two 20 mm / 0.78 in cannon. ==Operational service==