Ar.231 is a reconnaissance seaplane intended for operation from a submarine. Designed from the outset for use on "cruiser" submarines such as Type XI B, Ar 231. The aircraft was powered by a 119 kW (160 hp) Hirth HM 501 engine, weighed about 1000 kg and had a wingspan of 10 The design made it possible to create a simple and compact aircraft that could be installed in a transport cylinder with a diameter of only 2 m. For easy storage, the Ar 231 wing had removable sections that two operators could dismantle in less than six minutes. One of the unusual features of the wing design was its offset, in which the right wing root was attached to its inclined central part (raised above the fuselage) and was lower than the left wing root, thereby, the wing had the ability to quickly fold without additional operations.
The plane showed itself to be quite stable and stable, but the power of the power plant was clearly not enough. To get a speed boost, the plane was lightened to the limit. The best option was found when the fuel tank was filled to three quarters, which gave a gain of 50 kilograms with a still quite significant range.
A total of 6 aircraft were manufactured. It is known that two aircraft were equipped with the auxiliary cruiser "Stir", but their unsuitability for practical use was found out. On September 27, 1942, while the cruiser was in Bahia (Brazil), he came across the "Sephen Hopskins", an American Liberty-ship (armed with anti-aircraft guns). The battle began, as a result of which "Stir" received direct hits and burned down along with its planes.