The Ar 231 was a small open cockpit single-seat reconnaissance floatplane, built in detachable sections, to be stored on a U-boat. The Ar 231 was a parasol-wing design, but for easier storage the right wing was attached lower than the left wing, and the center section was angled. When dismantled they could be stowed in a tube 6 ft 7 in (2m) in diameter for carriage by the submarine when submerged. The Ar 231 could be stored in six minutes, but only four were built and flight-tested in 1941.
Ar 231 V1 Wn° 2310001, KK + BP,
Ar 231 V2 Wn° 2310002, KK + BQ
Ar 231 V3 Wn° 2310003, KK + BR
Ar 231 V4 Wn° 2310004, KK = BS

Engine: Hirth HM 501A, 160 hp
Propeller: two-blade wooden fixed pitch
Wingspan: 10,17 m
Length: 7,82 m
Height: 3,83 m
Wing area: 15,20 sq.m
Empty weight: 868 kg
MTOW: 1050 kg
Wing loading: 69 kg/sq.m
Power loading: 6,562 kg/hp
Maxspeed: 170 Kmh
Cruise: 130 Kmh
ROC: 1000 m in 6 min
Ceiling: 3000 m
Range: 510 km
Endurance: 4 hours

Development of the Arado Ar198 began in 1936 when the RLM issued a specification to the German aircraft industry calling for a plane specially suited to the short-range reconnaissance role. This specification was initially taken up by Arado, Blohm & Voss (Hamburger Flugzeugbau Division), Focke-Wulf, and Henschel. Each of these firms was able to base their design on previous aircraft and experience with this specific aircraft type and they were able to submit designs to the RLM within a short time. The requirement was to replace the Heinkel He 46 already in service with the Luftwaffe by an aircraft designed to make use of the most modern technology. This included the use of a powerful engine, good characteristics over the speed range, optimal vision for the crew and, protective and defensive features for the crew.

After various changes to the basic design, a contract for a pre-production series AradoAr 198A-0 was granted in July 1937.

For the Ar 198 a crew of three, consisting of pilot, gunner/radio operator, and observer, was planned. Due to the required optimal vision and high speed, a fully-enclosed crew compartment was built into the design. Tactical reconnaissance put a high emphasis on ground vision and the observer’s position was positioned below the wing plane for unobstructed vision, while the pilot and rear gunner were enclosed in an extensively glazed cabin above the wing plane. In this generously laid-out crew compartment there was an accessible connection to each crew position which resulted in good communications between crew members.

The entire forward fuselage structure, inclusive of the crew compartment, was of steel tube construction with the engine bearer included in this construction. Formers, light-metal fillets and a light-metal skin allowed for an aerodynamically advantageous shape. The rear fuselage was of an all-metal monocoque construction and purely as a tail-boom with no equipment for tactical missions installed. The Ar 198 had fixed landing gear.

The Ar 198 V1 (D ODLG) making its first flight in March 1938 at the Arado factory airfield at Warnemünde. During the early flights a marked instability in the projected low-speed range about all axes was noticed. It was thought that this was due to the large extension of the lower fuselage and consequently the layout was markedly changed for the second and third prototypes. In order to correct the flight characteristics the wings of the Ar 198 V1 were fitted with automatic slats which resulted in noticeable improvement in flight characteristic which also demanded considerable experience of the pilot.

A joint Ilmavoimat / Maavoimat / VL evaluation team flew this first prototype in July 1938 and generally rated it highly. Althought it demanded considerable experience to fly, performance was excellent, as was visibility.

The assembly process for the aircraft proved complex, with an associated high cost of production. Arado also had insufficient production capacity and this led the RLM to put a halt to the mass-production of the Arado Ar 198. Continued evaluation of the Ar 198 however, was not cancelled by that decision. The second prototype was completed and turned over to the Luftwaffe Flight Test Center at Rechlin. Soon after some very sucessful test flights this aircraft crashed on the landing approach when the starboard automatic slat came off, damaging the wing and forcing the pilot to make an emergency landing on rough ground. Damage to the airframe was such that restoration of the machine was not carried out. The Arado Ar 198 V1, however, after the elimination of a few faults, was flown for a long time with increasing enthusiasm on the part of its assigned crew. The third prototype was only 80 per cent completed and then used for static tests.

Engine: BMW Bramo Fafnir 323A-1, 900 hp
Wingspan: 14,9 m
Length: 11,8 m
Height: 4,5 m
Empty weight:: 2400 kg
MTOW: 3031 kg
Max speed: 359 kph / 223 mph
Stall speed: 70 mph
Landing speed: 55mph
Service ceiling: 26,250 ft
Range: 1081 km / 672 miles
Required runway TO MAUW: 600 m
Required runway landing MAUW: 510 m
Armament: 2 MG 17 7,92 mm, 1 MG 15 7,92 mm, 4 x 50 kg bombs
Crew: 3