TheArado Ar 231 was a lightweightfloatplane, developed duringWorld War II inNazi Germany as ascout plane forsubmarines byArado. The need to be stored inside the submarine necessitated compromises in design that made this single-seat seaplane of little practical use.
Arado Ar 231 model, front view, showing the special wing configuration
Designed from the outset for use onU-boat "cruisers", like theType XI B, the Ar 231 was a lightparasol-wing aircraft. The aircraft was powered by a 119 kW (160 hp)Hirth HM 501inline engine, weighed around 1,000 kg (2,200 lb), and had a 10 m (33 ft)wingspan. The design led to a simple and compact aircraft that could be fitted into a storage cylinder only 2 m (6 ft 7 in) in diameter. For ease of storage, the Ar 231's wings featured detachable sections that two operators could remove in less than six minutes. One unusual feature was an offset wing design, with the rightwing root attaching to the wing's tilted center section (elevated above thefuselage, as on all parasol-wing designs) and lower than the left wing root, to allow the wings to overlap whenfolded, so as to occupy less space.
Testing soon revealed the Ar 231s to be fragile, underpowered, and difficult to fly even during calm weather. Moreover, U-boat commanders were reluctant to linger on the surface for launch and retrieval[1] and, as a result, development ended in favour of theFocke Achgelis Fa 330gyroglider. Some of the testing was done on theauxiliary cruiserStier, two of the sixprototypes being taken on one voyage.
