By September, four prototypes were flying. The second prototype, Arado Ar 234 V2, crashed 2 October 1943 at Rheine near Münster after suffering a fire in its port wing, failure of both engines and various instrumentation failures, the aircraft diving into the ground from 4,000 feet (1,200 m), killing pilot Flugkapitän Selle. The eight prototype aircraft were fitted with the original arrangement of trolley-and-skid landing gear, intended for the planned operational, but never-produced Ar 234A version.
The sixth and eighth of the series were powered with four BMW 003 jet engines instead of two Jumo 004s, the sixth having four engines housed in individual nacelles, and the eighth flown with two pairs of BMW 003s installed within "twinned" nacelles underneath either wing. These were the first four-engine jet aircraft to fly. The Ar 234 V7 prototype made history on 2 August 1944 as the first jet aircraft ever to fly a reconnaissance mission.
The RLM had already seen the promise of the design and in July had asked Arado to supply two prototypes of a Schnellbomber ("fast bomber") version as the Ar 234B. Since the aircraft was very slender and entirely filled with fuel tanks, there was no room for an internal bomb bay and the bombload had to be carried on external racks. The added weight and drag of a full bombload reduced the speed, so two 20 mm fixed-mount, rearwards aimed MG 151 cannons were added in a remotely controlled tail position to give some measure of defence.
Since the cockpit was directly in front of the fuselage, the pilot had no direct view to the rear, so the guns were aimed through a periscope, derived from the type used on German World War II tanks, mounted on the cockpit roof. The system was generally considered useless, and many pilots had the guns removed to save weight. The external bombload, and the presence of inactive aircraft littering the landing field after their missions were completed (as with the similarly dolly/skid-geared Messerschmitt Me 163) made the skid-landing system impractical, so the B version was modified to have tricycle landing gear. The ninth prototype, marked with the Stammkennzeichen (radio code letters) PH+SQ, was the first Ar 234B, and flew on 10 March 1944.
The B models were slightly wider at the mid-fuselage to house the main landing gear, with a fuel tank present in the mid-fuselage location on the eight earlier trolley/skid equipped prototype aircraft having to be deleted for the retracted main gear's accommodation, and with full bombload, the aircraft could only reach 668 km/h (415 mph) at altitude. This was still better than any bomber the Luftwaffe had at the time, and made it the only bomber with any hope of surviving the massive Allied air forces. The normal bombload consisted of two 500 kg (1,100 lb) bombs suspended from the engines or one large 1,000 kg (2,200 lb) bomb semi-recessed in the underside of the fuselage with maximum bombload being 1,500 kg (3,310 lb). If the war had continued it is possible that the aircraft would have been converted to use the Fritz X guided bombs or Henschel Hs 293 air-to-surface missiles.
Production lines were already being set up, and 20 B-0 pre-production aircraft were delivered by the end of June. Later production was slow, however, as the Arado plants were given the task of producing planes from other bombed-out factories hit during the Big Week, and the ongoing license-building and nascent phasing-out of Heinkel's heavy He 177 bomber. Meanwhile, several of the prototypes were sent forward in the reconnaissance role. In most cases, it appears they were never even detected, cruising at about 740 km/h (460 mph) at over 9,100 m (29,900 ft), with the seventh prototype achieving the first-ever wartime reconnaissance mission over the United Kingdom by a Luftwaffe-used jet aircraft.
The few 234Bs entered service in the fall and impressed their pilots. They were fairly fast and completely aerobatic. The long takeoff runs led to several accidents; a search for a solution led to improved training as well as the use of rocket-assisted takeoff. The engines were always the real problem; they suffered constant flameouts and required overhaul or replacement after about 10 hours of operation.
The most notable use of the Ar 234 in the bomber role was the attempt to destroy the Ludendorff Bridge at Remagen. Between 7 March, when it was captured by the Allies, and 17 March, when it finally collapsed, the bridge was continually attacked by Ar 234s of III/KG 76 carrying 1,000 kg (2,200 lb) bombs. The aircraft continued to fight in a scattered fashion until Germany surrendered on 8 May 1945. Some were shot down in air combat, destroyed by flak, or "bounced" by Allied fighters during takeoff or on the landing approach, as was already happening to Messerschmitt Me 262 jet fighters. Most simply sat on the airfields awaiting fuel that never arrived.
Overall from the summer of 1944 until the end of the war a total of 210 aircraft were built. In February 1945, production was switched to the C variant. It was hoped that by November 1945 production would reach 500 per month.
Ar 234B-0 : 20 pre-production aircraft.
Ar 234B-1 : Reconnaissance version, equipped with two Rb 50/30 or Rb 75/30 cameras.
Ar 234B-2 : Bomber version, with a maximum bombload of 2,000 kg (4,410 lb).
In addition, a handful of B-2 airframes were adapted for the night-fighting role. These so-called Nachtigall (Nightingale) aircraft were fitted with FuG 218 "Neptun" VHF-band radar and carried a pair of forward-firing MG 151/20 autocannon within a Magirusbombe conformal gun pod on the ventral fuselage hardpoint. A second crewmember, who operated the radar systems, was accommodated in a very cramped compartment in the rear fuselage. Two of these jury-rigged night fighters served with Kommando Bonow, an experimental test unit attached to Luftflotte Reich. Operations commenced with the pair of 234s in March 1945, but Bonow's team soon found the aircraft to be unsuited for night fighting and no kills were recorded during the unit's very brief life.
The Ar 234C was equipped with four BMW 003A engines, mounted in a pair of twin-engine nacelles based on those from the eighth Ar 234 prototype. The primary reason for this switch was to free up Junkers Jumo 004s for use by the Me 262, but the change improved overall thrust, especially in takeoff and climb-to-altitude performance. An improved cockpit design, with a slightly bulged outline for the upper contour, also used a much-simplified window design for ease of production. Airspeed was found to be about 20% higher than the B series and the faster climb to altitude meant more efficient flight and increased range.
Although Hauptmann Diether Lukesch was preparing to form an operational test squadron, only 14 C-series airframes had been completed by war's end, and of that number fewer than half had been fitted with engines. Comprehensive flight testing of the new sub-type had yet to begin when Germany surrendered. Three basic variants of the C-series were planned for initial construction, with several more laid out as detailed proposals. Some of these would have had different powerplants, while others were intended to feature swept or "crescent"-type wings.
Ar 234C-1 : Four-engined version of the Ar 234B-1.
Ar 234C-2 : Four-engined version of the Ar 234B-2.
Ar 234C-3 : Multi-purpose version, armed with two 20 mm MG 151/20 cannons beneath the nose.
Ar 234C-3/N : Proposed two-seat night fighter version, armed with two forward-firing 20 mm MG 151/20 and two 30 mm (1.18 in) MK 108 cannons, fitted with a FuG 218 Neptun V radar.
Ar 234C-4 : Armed reconnaissance version, fitted with two cameras, armed with four 20 mm MG 151/20 cannons.
Ar 234C-5 : Proposed version with side-by-side seating for the crew. The 28th prototype was converted into this variant.
Ar 234C-6 : Proposed two-seat reconnaissance aircraft. The 29th prototype was converted into this variant.
Ar 234C-7 : Night fighter version, with side-by-side seating for the crew, fitted with an enhanced FuG 245 Bremen O cavity magnetron-based centimetric (30 GHz) radar.
Ar 234C-8 : Proposed single-seat bomber version, powered by two 1,080 kg (2,380 lb) Jumo 004D turbojet engines.
Ar 234D
The D model was a two-seat aircraft based on the B-series fuselage, but with a new, enlarged two-seat cockpit possessing fewer glazing panels than the C version, intended to be powered by a pair of more powerful Heinkel HeS 011 turbojet engines. The HeS 011 powerplant never reached quantity production, with only 19 examples of the new powerplants ever created for test purposes, and no 234D was produced.
Ar 234D-1 : Proposed reconnaissance version. Not built.
Ar 234D-2 : Proposed bomber version. Not built.
Ar 234E
The E model was a heavy fighter variant of the D model. It was not produced.
Ar 234P
The P model was a two-seat night fighter version with a variant of the D-series cockpit, differing in powerplant options and several options of radar. Several were in the planning stage, but none made it into production.
Ar 234P-1 : Two-seater with four BMW 003A-1 engines; one 20 mm MG 151/20 and one 30 mm (1.18 in) MK 108.
Ar 234P-2 : Also a two-seater, with redesigned cockpit protected by a 13 mm (0.51 in) armour plate.
Ar 234P-3 : HeS 011A powered P-2, but with two each of the cannon.
Ar 234P-4 : as P-3 but with Jumo 004D engines.
Ar 234P-5 : Three-seat version with HeS 011A engines, one 20 mm MG 151/20 and four 30 mm (1.18 in) MK 108s.
Although a successful design, the small number manufactured, combined with shortage of fuel and lack of experienced airmen, meant that the Ar 234 failed to make any significant impact on the course of the war. The revolutionary bomber simply came too late, and was nowhere near as successful in operational terms as the Messerschmitt Me 262. At the end of World War II some surviving Luftwaffe jets, including several Ar 234s, made their way to Norway to escape capture by the Allies. These were eventually surrendered to the British and three of the Ar 234s were subsequently taken to the United States for evaluation.
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