The single-seat S 13 was built in 1924 as an equi-span biplane with cantilever wings utilising a thick Zhukovsky section. During the initial flight test programme, test pilots were nervous of the cantilever wing arrangement and, in consequence, N-type (later replaced by Vee-type) steel-tube interplane struts were added. The S 13 was fitted with a Skoda HS 8 water-cooled engine of 295 hp originally intended to have a ring-type frontal radiator, but fitted, as a result of difficulties experienced with this cooling arrangement on other fighters, with a ventral radiator. Although the S 13 demonstrated good flying characteristics, some problems were experienced with stability and development was abandoned.
Engine: 1 x 295 hp V-8 Skoda 8Fb
Max speed, 143 mph (230 km/h)
Time to 16,405 ft (5000 m): 18.15 min
Range, 342 mls (550 km)
Empty weight, 1,742 lb (790 kg)
Loaded weight, 2570 lb (1 166 kg)
Span, 26ft 2 9/10 in (8.0m)
Length, 22ft 10 3/8 in (6.97m)
Height, 9ft 4.5in (2.86m)
Wing area, 215.29 sq ft (20sq m).