Arado Ar 232

The Ar 232 Tausendfüssler ("millipede" in German) was the first truly modern transport aircraft, designed and built in small numbers by Arado during World War II. The design introduced almost all of the features now considered to be "standard" to transports, including a low-slung box-like fuselage, rear loading ramp, a high tail for easy access to the hold, and various features for operating from rough fields. Although the Luftwaffe was interested in replacing (or supplanting) their fleet of outdated Ju 52/3m's, they were overloaded with types at the time and did not purchase large numbers of the aircraft.

The Ar 232 design led from a tender offered by the RLM in autumn 1939 for a replacement for their outdated Ju 52's. Both Arado and Henschel were asked for rear-loading designs powered by two 1,600 hpBMW 801A/B engines, which was just entering prototype production and not currently used on any "front line" designs. The Arado design beat out the Henschel design after an examination of the plans, and an order for three prototypes was placed in 1940.

At Arado design of the 232 under the direction of Wilhelm van Nes. The design started with the cargo area, with a bay directly behind the cockpit that extended 6.6m to the rear, 2.3m wide and 2.0m high. Typical designs of the era would use a side-mounted door for access, but the 232 used hydralically powered clamshell-doors on the rear of the bay with a ramp to allow cargo to be rolled into the hold. The tail control surfaces were mounted on the end of a long boom to keep the area behind the doors clear so trucks could drive right up to the ramp. This allowed the 232 to be loaded and unloaded much more quickly than other designs.

For short-field performance, the 232 incorporated Arado's own "travelling flap" design for the entire rear surface of the wing. Even fully loaded to 16,000kg the plane could take-off in 200m. This distance could be further improved upon with the used of RATO for take-off, and either parachutes or RATO for landing.

The most noticeable feature of the 232 was the landing gear. Normal operations from prepared runways used tricycle gear, but they could "break" after landing to lower the fuselage closer to the ground and thereby reduce the ramp angle. An additional set of 11 smaller wheels (per side) supported the aircraft once "broken", or could be used for additional support when landing on soft airfields. The appearance of the row of small wheels led to the nickname "millipede". In flight the main legs fully retracted into the engine nacelles, while the support wheels remained extended and the nose wheel only semi-retracted.

Normally operated by a crew of four, the pilot was the only member without two jobs. The navigator operated a MG 81Z in the nose, the radio operator another in a rotating turret on the roof, and the loadmaster another firing rearward from the extreme rear of the cargo bay above the cargo doors.

Even before the prototytes were complete in 1941, the Focke-Wulf Fw 190 project had moved to the BMW 801 engine, and was proving to be a capable design. Production of the 801 wasn't enough to supply even this need, and the 232 was forced to choose another engine. Eventually the Bramo 323 from the Ju 252 was selected instead, as it was already in production and could meet their needs if the 232 really did replace the 52 in service. The prototypes were far enough along that switching engines would have seriously delayed the program, so the first two were to be completed as the Ar 232A, and the third and a newly ordered fourth as the Ar 232B.

The first two prototypes, GH+GN and VD+YA, started trials in early 1941. The first flight resulted in the collapse of the nose gear, but the milipede wheels saved the plane from damage. A further ten pre-production machines were built, and were used operationally as the Ar 232A-0 while awaiting production versions. In general the 232 completely outperformed the Ju 52. It carried roughly double the load over longer distances, operated from much shorter runways and considerably worse fields if need be, and cruised about 70km/h faster.

The Ar 232B program ran at the same time. With four 1,000hp Bramo 323's, the plane increased in power from 3,200hp to 4,000hp, solving the A model's problem of having little excess power in the case of engine failure. This change also required the wing to be extended slightly, the span rising just over 3m in total. The extra weight of the engines also moved the center of gravity forward, which was offset by extending the cargo area rearward another meter.

Two prototypes were ordered, V3 and V4, and V3 first flew in May 1942. A further 10 were then ordered as the Ar 232B-0, and were used widely in an operational role. However this was the only order for the design, as the Luftwaffe gave transport aircraft production a very low priority. Many of those produced were used by Arado to transport aircraft parts among their factories, and did not see front-line service. Guns on the B series were the typical "mix-n-match" found on many German wartime designs, typically with a 13 mm MG 131 in the nose and one or two in the tail, with a 20 mm MG 151/20 in the roof turret.

Plans were also made to replace the outer wing sections and control surfaces with wooden versions to conserve now-limited supplies of aluminum. Originally to be known as the Ar 232C, the design dragged on and was later re-named as the Ar 423. Plans were finally put into place to start production in October 1945, but the war ended without even a prototype being produced. An even larger version, the Ar 523 (and sometimes 623) almost doubled the wingspan to 60m and added another two engines.

Two of the B-0s were later captured by the British at the end of the war. After test flights by Eric Brown, who gave the design excellent marks, they were used by the Royal Air Force on flights between England and Germany after the war.

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