Kauba designed also an extremely clean single-seat fighter trainer, the Sk V4, powered by a 240 hp Argus As 10C-3 eight-cylinder air-cooled inverted V-engine. Impressed by its performance the RLM ordered four prototypes of a more powerful version that was designated Sk 257.
Powered by a 485 hp Argus As 410 twelve-cylinder air-cooled inverted V-engine, the type first flew in 1943.
Span: 24 ft 11.2 in (7.6 m)
Length: 23 ft 3.5 in (7.1 m)
Wing area: 90.42 sq ft (8.4 sq.m)
Max speed: 217 mph (350 kmh)