Arado Ar 234 Blitz
The Arado Ar 234 Blitz is a jet-powered bomber designed and produced by the German aircraft manufacturer Arado. It was the world's first operational turbojet-powered bomber, seeing service during the final months of the Second World War.
Development of the Ar 234 can be traced back to the latter half of 1940 and the request to tender from the Ministry of Aviation to produce a jet-powered high-speed reconnaissance aircraft. Arado was the only respondent with their E.370 design. While its range was beneath that of the Ministry's specification, an initial order for two prototypes was promptly issued to the company, designated Ar 234. While both of the prototypes had been mostly completed prior to the end of 1941, the Junkers Jumo 004 turbojet engines were not available prior to February 1943. Due to engine unreliability, the maiden flight of the Ar 234 V1 was delayed until 30 July 1943. In addition to the original reconnaissance-orientated Ar 234A, the fast bomber Ar 234B model was developed in response to a request by the Ministry of Aviation. Due to a lack of internal space in the relatively slender fuselage, bombloads of up to had to be carried on external racks rather than in internal bomb bays.
The Ar 234 was produced only in small numbers, despite plans for production of 500 per month by late 1945. This was partly due to a lack of available jet engines and other critical materials, for which the aircraft had to compete with other types, such as the Messerschmitt Me 262. Several models were proposed, with alternative engines, cockpit improvements, and adaptations for other roles, including as a night fighter. In late 1944, aerial reconnaissance missions over enemy territory commenced. The Ar 234 was almost entirely used to perform such reconnaissance missions, and it was in this capacity that it became the last Luftwaffe aircraft to overfly the United Kingdom during the war, in April 1945. In its capacity as a bomber, the most prominent use of the Ar 234 was the repeated attempts to destroy the Ludendorff Bridge at Remagen between 7 and 17 March 1945. Many airframes were destroyed or captured on the ground due to a lack of serviceable engines or fuel.
Design and development
Background
During the closing months of 1940, the Nazi German Ministry of Aviation offered a tender for a jet-powered high-speed reconnaissance aircraft with a range of. Arado was the only company to respond, offering their E.370 project, led by Professor Walter Blume. The design was of a high-wing mostly conventional-looking aircraft powered by a pair of Junkers Jumo 004 turbojet engines, one beneath each wing.Arado estimated that the E.370 would possess a maximum speed of at, an operating altitude of and a range of. While the range was less than the Ministry's specification, it was decided to order a pair of prototypes, designated the Ar 234. These were largely complete before the end of 1941, but the Jumo 004 engines were not ready until February 1943. When they did arrive, Junkers considered the engines too unreliable for in-flight use and they were only cleared for ground tests. Months later, flight-ready engines were finally delivered and on 30 July 1943, the Ar 234 V1 made its first flight from Rheine airfield.
The second prototype, V2, crashed on 2 October 1943 at Rheine near Münster after suffering a fire in its port wing, the failure of both engines, and instrumentation failures. The aircraft dived into the ground from, killing the pilot. Later that year the third prototype, V3, was demonstrated to Adolf Hitler at Insterberg; he was enthusiastic about the aircraft and authorised Arado to obtain factory personnel, raw materials, and the funds necessary to build two hundred by the end of 1944. The eight prototype aircraft were fitted with the trolley-and-skid landing gear intended for the never produced Ar 234A version.
The sixth and eighth in the series were powered by four BMW 003 jet engines instead of two Jumo 004s; the sixth had the four engines in individual nacelles, while the eighth had the engines in "twinned" nacelles underneath each wing. A 1942 engineering drawing of the E 370 showed a forward tank, a mid-fuselage tank, and an rear tank with a capacity. These were the first four-engined jet aircraft to fly. The twin-Jumo 004 powered Ar 234 V7 prototype was the first jet aircraft used for a reconnaissance mission, on 2 August 1944.
Landing gear design
The projected weight for the aircraft was approximately. To reduce weight and maximize internal fuel capacity, Arado did not use retractable landing gear. Instead, the aircraft was to take off from a jettisonable tricycle gear-style trolley, and land on three retractable skids, one under the central section of the fuselage and one under each engine nacelle. The main skid, beneath the fuselage, was originally intended to retract fully, and was originally shown in a 1942-dated engineering drawing, under the E 370 airframe factory development designation, as intended to be made from a three-sided channel-section component, featuring a set of nine triple-beaded wooden rollers within the channel-section main skid. However, this landing gear did not allow aircraft to move independantly after landing, which would have left aircraft scattered over an airfield, unable to taxi off the runway. Erich Sommer said that landing the skid-equipped prototypes on a wet grass airstrip "was like greased lightning" and "like soap", due to the complete lack of braking capability.Ar 234B
At the request of the Ministry of Aviation, Arado also produced a pair of prototypes configured as fast bombers, as the Ar 234B. On 12 March 1944, the first of these, Ar 234 V9, performed its first flight. It was the first to feature a fully retractable tricycle landing gear, with the main gear retracting forward into the mid-fuselage, and the nose gear retracted rearwards.The Ar 234's slender fuselage was largely filled with fuel tanks, leaving no room for an internal bomb bay, which was carried on external racks. The forward-set cockpit did not provide the pilot with any visibility to the rear, thus the rear firing guns it was fitted with were aimed through a periscope, mounted on the cockpit roof. This periscope could also be flipped forwards for dive-bombing however, its usefulness was impaired by the scope's image being flipped upside down. The defensive fixed rear gun system was found to be useless by the pilots, and was omitted in the Ar 234B. The aircraft was widened slightly at mid-fuselage and the central fuel tank was omitted to fit in the main landing gear, while enlarged forward and aft fuel tanks compensated for its removal.
During flight testing, while carrying its maximum bombload of three SC 500 bombs, the Ar 234 V9 could reach at, faster than any other Luftwaffe bomber at the time. The normal bomb load consisted of a pair of bombs suspended from the engines or one large bomb semi-recessed in the underside of the fuselage, while the maximum bombload was. It could also carry the heavier BT 1400, although the ground clearance was limited. If this munition was deployed, the aircraft's fuel capacity was noticeably reduced while rocket assistance was needed for takeoff. The pilot would engage the autopilot while using the bomb sight, which was interfaced with the autopilot to adjust the aircraft's flight path directly.
Production lines were being set up while the 20 B-0 pre-production aircraft were being delivered, by the end of June. Production was slow, as Arado was to maintain production to compensate for other factories bombed during the USAAF's "Big Week",, in addition to an ongoing license-construction of the Heinkel He 177 heavy bomber. Between mid-1944 and the end of the conflict, only 210 aircraft were built. During February 1945, production switched to the C variant. German plans were for production to reach 500 per month by November 1945.
In addition, some Ar 234 B-2 airframes were modified to serve as night fighters. Designated Ar 234B-2/N and code named Nachtigall, these were fitted with FuG 218 "Neptun" VHF-band radar, with a reduced-dipole length version of the standard Hirschgeweih eight-dipole element, VHF-band transceiving air interception radar antenna system, and carried a pair of forward-firing 20mm MG 151/20 autocannon within a Magirusbombe conformal gun pod on the rear fuselage hardpoint. The radar system was operated by a second crew member in a cramped compartment in the rear. Two of these served with Kommando Bonow, a Luftflotte Reich experimental test unit. Operations began in March 1945, but the aircraft was unsuitable for night fighting and no kills were made.
Ar 234C
The Ar 234C was equipped with four lighter BMW 003A engines mounted in a pair of twin-engine nacelles based on those from the eighth prototype. The primary reason for this switch was to free up Junkers Jumo 004s for the Me 262, but it also improved takeoff power to nearly. An improved cockpit, with a slightly bulged outline in the upper contour, and integrating a swept-back fairing for the periscope, and a simplified window design with 13 glazed panels reduced to 8. The BMW jet engines improved top speed by about 20% over the B series airframes.The C-1 was intended for reconnaissance, the C-2 for bombing, and the C-3 for bombing, ground attack or night fighting.
During October 1944, the prototype Ar 234 V19 performed its first flight. Although an operational test squadron was being prepared, only 14 C-series airframes were completed by the end of the war, with fewer than half having engines. Some were found at the end of the war sitting in the open, complete but for empty engine nacelles. Flight testing of the new sub-type hadn't started yet when Germany surrendered. Three basic variants of the C-series were planned, with several more laid out as detailed proposals. Some of these would have had a pair of the higher thrust, but heavier Heinkel HeS 011 jet engines, while others were to have swept or "crescent"-type wings.