Arado Ar 232 The Arado Ar 232 " Tausendfüßler " ( German : " Millipede " ) , sometimes also called " Tatzelwurm " , was one of the first truly modern cargo aircraft , designed and built in small numbers by the German firm Arado Flugzeugwerke during World War II . The design introduced , or brought together , almost all of the features now considered to be " standard " in modern cargo transport aircraft designs , including a box - like fuselage slung beneath a high wing ; a rear loading ramp ( that had first appeared on the October 1941 - flown Junkers Ju 252 trimotored transport via its " Trapoklappe " ) ; 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 Although the " Luftwaffe " was interested in replacing or supplementing its fleet of outdated Junkers Ju 52 / 3m transports , it had an abundance of types in production at the time and did not purchase large numbers of the Ar 232 . Design . The Ar 232 design resulted from a tender offer ed by the " Reichsluftfahrtministerium " ( German Air Ministry , RLM ) in late 1939 for a replacement for the Ju 52 / 3m transport . Both Arado and Henschel were asked for rear - loading designs powered by two 1 , 193 kW ( 1 , 600 hp ) BMW 801A / B radial engines , which was just entering prototype production and not currently used on any front - line designs . The Arado design beat out Henschel ' s after an examination of the plans , and an order for three prototypes was placed in 1940 . Wilhelm van Nes led the design of the Ar 232 . He began at the cargo area , with a bay directly behind the " stepless cockpit " that was 6 . 6 m ( 21 ft 7¾ in ) long , 2 . 3 m ( 7 ft 6½ in ) wide and 2 . 0 m ( 6 ft 6¾ in ) high . Typical designs of the era would use a side - mounted door for access , but the Ar 232 used hydraulically 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 Ar 232 to be loaded and unloaded faster than other designs . For short - field performance , the Ar 232 incorporated Arado ' s own " travelling flap " design for the entire rear surface of the wing . Even loaded to 16 , 000 kg ( 35 , 270 lb ) , it could take - off in 200 m ( 656 ft ) . This distance could be further reduced by using rocket assist ( RATO ) for take - off , and either parachute s or reverse RATO for landing . The most noticeable feature of the Ar 232 was the landing gear . Normal operations from prepared runways used a tricycle gear , but the struts could " break " , or kneel , after landing to place the fuselage closer to the ground and thereby reduce the ramp angle . An additional set of ten or eleven smaller , non - retractable twinned wheels per side supported the aircraft once the main landing gear ' s lever - action lower oleo - strut suspended arm - carrying the main gear ' s wheel / tire unit - was " broken " , or could be used for additional support when landing on soft or rough airfields . The aircraft was intended to be capable of taxiing at low speeds on its row of small wheels , thus being able to negotiate small obstacles such as ditches up to 1 . 5 m ( 5 ft ) in width . 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 fixed support wheels remained exposed and the nose wheel only semi - retracted . Normally operated by a crew of four , the pilot was the only member without two roles . The navigator operated a 13 mm ( . 51 in ) MG 131 machine gun in the nose , the radio operator a 20 mm MG 151 cannon in a rotating turret on the roof , and the loadmaster a 13 mm ( . 51 in ) MG 131 machine gun firing rearward from the extreme rear of the cargo bay above the cargo doors . Development . Even before the prototypes were complete in 1941 , the Focke - Wulf Fw 190 project had been earmarked to use the BMW 801A / B , and was proving to be a capable design . Production of the BMW 801 was insufficient to supply this new demand , and the Ar 232 was forced to use another engine . Eventually , the BMW Bramo 323 from the Junkers Ju 352 was selected instead , as it was already in production and could meet requirements if the Ar 232 really did replace the Ju 52 / 3m 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 third and fourth prototypes ( and all production aircraft ) used four engines ( in place of the two specified in the RLM specification ) in order to provide the desired performance . The first two prototypes , bearing the " Stammkennzeichen " alphabetic codes GH + GN and VD + YA respectively , started trials in early 1941 . The first flight resulted in the collapse of the nose gear , but the millipede wheels saved the aircraft 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 Ar 232 completely outperformed the Ju 52 / 3m . It carried roughly double the load over longer distances , operated from shorter runways and rougher fields if need be , and cruised about 70 km / h ( 44 mph ) faster . The Ar 232B program ran at the same time . With four 895 kW ( 1 , 200 hp ) Bramo 323s , power increased from 2 , 386 kW ( 3 , 200 hp ) to 3 , 580 kW ( 4 , 800 hp ) , solving the A model ' s problem of having little excess power in case of engine failure . This change also required the wing to be extended slightly , the span increasing just over 3 m ( 9 ft 10 in ) 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 four - engined prototypes were ordered , the 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 between its factories , and did not see front - line service . Plans were also made to replace the outer wing sections and control surfaces with wooden versions to conserve aluminium . Originally to be known as the Ar 232C , the design dragged on and was later renamed the Ar 432 . Plans were finally put into place to start production in October 1945 , but the war ended without even a prototype being produced . Two even larger planned versions , the Ar 532 and the Ar 632 , would have almost doubled the wingspan to 60 m ( 196 ft 10 in ) and added another two engines . Two of the B - 0s were captured by British forces at the end of the war . After test flights by Eric " Winkle " Brown , who gave the design excellent marks , they were used by the Royal Air Force on flights between England and Germany after the war .