Authored By Dan Alex (Updated: 5/18/2016):
The German Need
Origins of the Ar 234 can be traced back in an original late-1930s German Air Ministry (the RLM = Reichluftfahrtminiserium) initiative requiring a new, high-speed naval reconnaissance platform. To this point, the Germans relied upon a collection of seaplanes and flying boats for the role though performance garnered from these machines were less than stellar (apart from their inherently excellent operational ranges). These aircraft were highly susceptible to enemy interception for they lacked the needed performance and handling to evade incoming threats - particularly those embodied by nimble, maneuverable fighter types being fielded by the Allies.
The Air Ministry Requirement
In the fall of 1940, the Air Ministry agreed to a new design that would fly higher than enemy defenses could reach and fly faster than enemy aircraft could intercept. The optimal combat radius would be 1,240 miles with a maximum ferry range of at least 1,340 miles. This requirement specifically centered on a turbojet-powered design despite the technology being in its infancy at the time. Officials understood the potential power behind turbojet technology and its revolutionary effect on the world of military aviation - deciding this as the best avenue of approach. Work on such engines was already underway by brand names such as Junkers and BMW. At any rate, a turbojet-powered aircraft would allow the Air Ministry specifications to be fulfilled in whole though presenting substantial technological challenges to involved German engineers.
The E.370 Submission
The Arado concern was the only respondent for the fast reconnaissance bomber design. The firm held a proven pedigree with a stable of talented engineers to see the program through - led by Walter Blume who governed Arado through to its end in 1945. He, along with Hans Rebeski and Rudinger Kosin, were credited with the Ar 234's official concept. Arado completed and submitted their formal proposal in 1941 with the developmental aircraft assigned the designation of "E.370". After formal acceptance by the German Air Ministry, the design came to be known under the "Arado Ar 234" name. The Air Ministry then commissioned for six prototype vehicles in April of 1942 to further prove the design viable. By the end of the year, the order had increased to 20 total airframes. From the end of 1941 into 1942, two complete airframes were built, though The Junkers Jumo engines were not available until 1943 leading to a critical delay in the program for serial production was slated to begin that same year. The Ar 234 was, therefore, not made ready until February of 1943.
Arado Ar 234 Walk-Around
The Arado Ar 234 utilized a very distinct planform, one of the most recognizable of all of the wartime jet designs. The fuselage was pencil-like in its approach with a rounded nose cone and well-tapered rear. The entire nose was made up of the single-seat cockpit which provided excellent visibility of the oncoming action with only light framing being involved. Only views to the rear were blocked by the integrated fuselage spine which ran the length to form the tail section. The rounded fuselage incorporated slab sides for a deep approach required of the internal fuel stores, avionics and cockpit. Engines were held in streamlined nacelles, the base Ar 234 model fitting one engine to each wing. Wings themselves were straight appendages, high-mounted along the fuselage sides. The tail unit consisted of a single curved vertical tail fin with a pair of horizontal planes mounted higher than the main wing elements. In the definitive B-models, the undercarriage was wholly-retractable and arranged in a tricycle format with two main landing gear legs and a nose leg. All three positions held a large "donut-style" landing wheel of low pressure, intended to counter the rather narrow undercarriage track.
The Arado Ar 234 is Born Without Legs
Original Ar 234 prototypes lacked the complete tricycle undercarriage, hampered by the design's thin fuselage whose volume was already taken up by a mass of other important equipment, primarily the fuel stores required of long operational ranges. As such, the vehicle was launched from a jettisonable three-wheeled trolley mimicking what would become the finalized undercarriage (complete with steerable nose and wheel brakes). Landing would be accomplished by way of a skid attached to the belly of the aircraft and skids under the engine nacelles. The first Ar 234 turbojet-powered prototype finally achieved first flight on July 15th, 1943 from Rheine Airfield and the five other prototype aircraft soon followed the initial V1. Of the six initial vehicles completed, two were reserved as static test beds for a four-engined development still to come.
The Arado Ar 234A and V-Prototypes
The Ar 234 series was forged through a bevy of ever-evolving prototypes beginning with V1. Prototypes V1 through V5 utilized the trolley system for take-off and the landing skid for recoveries. All were powered by the Junkers Jumo 004 turbojet. V1 recorded its first flight on June 15th, 1943. V3 was given an ejector seat and pressurized cockpit while being outfitted with rockets for assisted take-off. Prototypes V6 and V8 were four-engined developments that begat the Ar 234C model detailed below. The V6 prototype managed its 4 x BMW 003 engine installations across four individual nacelles whereas the V8 relied upon paired nacelles in two pods, one pod to a wing. The V7 was the primary developmental form for the Ar 234B production line though it retained the trolley take-off and landing skid arrangement. Prototypes V9 through V11 instituted a conventional powered tricycle undercarriage through a deeper fuselage design. These led to the Ar 234B as well. V13 and V20 were four-engined developments influencing the Ar 234C line and fitted with 4 x BMW 193-003 engines in paired nacelles. V20 was lost during an April 4th, 1944 Allied bombing raid over Wesendorf. V15 was a single engine testbed for 2 x BMW 003 turbojet installations. V16 was developed around a crescent-shaped wing though her testing facility was overrun by British land forces before the aircraft could be finalized, the project being destroyed in the subsequent battle. V19 undertook its first flight on September 30th, 1944. V21 through V30 prototypes developed the C-model line further. V26 and V30 in particular were noted for their use of a laminar flow wing assembly.
The first early, near-production forms became the Ar 234A which were essentially prototypes V1 through V8 with their trolley/skid undercarriages.
The Arado Ar 234B
With the undercarriage issue resolved beginning with V9, the Ar 234B-0 represented 20 pre-production units with the final example completed in June of 1944. The initial Ar 234B-0 mark went airborne for the first time on June 8th, 1944 though without the planned cockpit pressurization and ejection seat feature. The Ar 234B-1 were unarmed reconnaissance versions fitted with cameras. The Ar 234B-1 managed to be completed with the promised autopilot function and operated with auxiliary fuel tanks for increased range. The Ar 234B-2 were bomber versions capable of 3,300lbs of stores and made operation in late 1944, remaining active into 1945. Rauchgerate Rocket-Assisted Take-Off (RATO) could be utilized to project faster take-off times and shorter runway distances as well as a spectacular initial rate-of-climb - very useful in interception. Long landing runs could then be offset by way of brake parachutes. Some Ar 234B-2 models were outfitted with radar facilities and a ventral gunpack with a second cockpit aft for utilization in the night fighter role. The design proved aerodynamically efficient and relatively stable with little in the way of engineering corrections required. Thusly sound, the B-model was the standardized form of the Ar 234 for the near future. These versions instituted an ejection seat, Patin PDS autopilot system and, due to the thirsty nature of early turbojet engines, given optional external auxiliary fuel tanks for improved range. The cockpit was fully pressurized to coincide with the high altitudes the Ar 234 would have to operate in requiring an onboard oxygen supply and feed. Power of these models would be served through 2 x Junkers Jumo 004B series turbojet engines. The Ar 234B series models would become the definitive operational-level production-quality mounts of the entire "Blitz" line, seeing combat service into 1945.
Only there two B-model forms were used in an operational manner - the Ar 234B-1 unarmed reconnaissance platform and the Ar 234B-2 dedicated bomber. The B-2 was further broken down in subvariants as in the Ar 234B-2/1 target-marking platform ("pathfinder"), the Ar 234B-2/b dedicated reconnaissance and the Ar 234B-2/r outfitted with auxiliary fuel tanks. Ar 234B production totaled 210 units. The Ar 234B-3 was intended as a dedicated bombing platform but given up for good with the emergence of the Ar 234C detailed below.