Other designs in the series included the V6 twin-boom pusher monoplane, none of which entered production.

Even before work on the Sk 257 began, Otto Kauba had begun work on a full-fledged fighter to have a 1,750 hp Daimler Benz DB-603 engine. Though it was in direct competition with the Focke-Wulf Ta 152, the RLM were not interested and it did not enter production.

The Škoda-Kauba Flugzeugbau produced the Škoda-Kauba V4 as a single-seat low-wing cantilever monoplane powered by a 240 hp (179 kW) Argus As 10C-3 engine with a retractable tailwheel landing gear. First flying in 1943, the first prototype proved very fast for its low power. The second included a number of changes and, despite increased power, was not as fast. A third was also completed.

The SK V4 fighter trainer was the only Otto Kauba design put in to production as the SK 227. The production was somewhat limited though.

The potential for development was recognized and the German Reichsluftfahrtministerium ordered four prototypes of an enlarged aircraft with a more powerful 485 hp Argus As 410 engine and allocated the designation Sk 257. The four prototypes performed well and the type was ordered into production but the build quality of the prototypes did not pass the Luftwaffe quality control inspections and after only five production aircraft had been built the order was cancelled.

The SK257 development received a German production order and five were completed before the Russians captured the factory.

SK V4
Engine: 1 x 240hp Argus As 10C-3
Max take-off weight: 1250 kg / 2756 lb
Wingspan: 7.60 m / 24 ft 11 in
Length: 5.60 m / 18 ft 4 in
Height: 2.90 m / 9 ft 6 in
Max. speed: 420 km/h / 261 mph
Ceiling: 7500 m / 24600 ft
Range: 900 km / 559 miles
Crew: 1

SK 257
Engine: 1 × Argus As 410 362 kW (485 hp)
Wingspan: 7.6 m (24 ft 11 in)
Wing area: 8.4 m2 (90 sq ft)
Length: 7.1 m (23 ft 4 in)
Maximum speed: 350 km/h (217 mph, 189 kn)
Crew: 1

On 7 May 1943 three young engineers sat in the Bacchi Wapen restaurant in Stockholm together with Åke Forsmark, manager of Skandinaviska Aero, and chatted about aircraft. The three were Erik Bratt, Karl-Erik Hilfing and Björn Törnblom, all students at Kungliga Tekniska Högskolan, the Royal Technical University in Stockholm. Their ideas gradually evolved into this sketch, on the back of a menu. It was originally meant to be a glider towing aircraft, and by May 1944 the design work was complete, with 4,000 drawings and 2,500 load calculations, performed by Törnblom, the only one of the three who had previous experience in aircraft design. He also designed the wings, fin and rudder. Hilfig was responsible for the fuselage and Bratt worked on the engine installation, propeller and landing gear.

The BHT-1 is a wooden low-wing cantilever monoplane with a retractable tailwheel landing gear. Powered by a 60 hp (45 kW) Walter Mikron 4 piston engine it has an enclosed single-seat cockpit. The wings include slotted flaps.

The BHT-1 Beauty was built by Skandinaviska Aero of Stockholm and first flew on 4 December 1944. Only one, SE-ANX, wa built.

The BHT-2 was a proposed two-seat development. A prototype constant speed propeller was developed for the aircraft using differential between engine oil, and ram air pressure to control pitch.

Gallery

Engine: 1 × Walter Mikron 4, 45 kW (75 hp)
Length: 5.80 m (19 ft 0 in)
Wingspan: 6.82 m (22 ft 4½ in)
Height: 1.90 m (6 ft 3 in)
Wing area: 7 m2 (75.3 ft2)
Empty weight: 240 kg (538 lb)
Gross weight: 420 kg (924 lb)
Maximum speed: 250 km/h (155 mph)
Cruising speed: 210 km/h (130 mph)
Range: 1700 km (1056 miles)
Service ceiling: 7500 m (24600 ft)
Crew: 1