The first product of Bücker Flugzeugbau GmbH, established at Johannisthal, Germany during October 1933, was a two-seat light trainer known as the Bücker Bü 131 Jungmann (Young Man). Designed by Anders J. Andersson, the company's Swedish chief engineer, it was a conventional single bay biplane with fabric-covered wooden wings, a welded steel-tube fuselage that, with the exception of light alloy around the engine and cockpit, was also fabric-covered, and a wire-braced tail unit of similar construction to the fuselage. The tailwheel type landing gear had rather stalky main units, and power for the prototype (D-3150), was first flown on 27 April 1934, and was provided by an 80 hp (60 kW) Hirth HM 60R inline 4-cylinder engine.

A Swiss operated Bücker Bü 131B (HB-UUA) Jungmann "Young Man"

The Bü 131A, as the initial production version was designated, proved to be very successful, being manufactured not only for civil flying schools in Germany but also for the Luftwaffe, although production figures do not appear to have survived. They consisted not only of the initial production Bü 131A, but also an improved production Bü 131B which had a more powerful Hirth HM 504A-2 engine. An experimental BU 131C was built, powered by a 90 hp (67 kW) Cirrus Minor engine, but following testing this version was not put into production. Bücker exported production aircraft for service in some eight European countries with the largest numbers going to Hungary (100) and Romania (150), and in addition 75 were licence-built in Switzerland. The most extensive licence-construction was in Japan, where 1,037 were built for the Japanese army as the Type 4 Primary Trainer (Ki-86A) by Kokusai. This followed the initiation of production on behalf of the Japanese navy for which it was licence-built by Watanabe (later Kyushu) as the Navy Type 2 Primary Trainer Model 11 (K9Wl). Production figures for the Japanese navy version differs according to source, varying from 217 to 339, but it seems reasonably certain that more than 200 were used as the navy's standard primary trainer.

Used throughout World War II by the Luftwaffe, the Bü 131 was later displaced by the improved Bucker Bü 181 Bestmann, and many saw service with auxiliary ground attack squadrons. Carrying 2.2 lbs (1 kg) and 4.4 lbs (2 kg) bombs, they were used by night to maintain nonstop harassment over Soviet lines. Like other classic trainers, many Bü 131s survived the war, and they were even built by Aero in Czechoslovakia during the 1950s under the designation C.4.

Development History & Variants

Bücker Bü 131 Prototype (D-3150) - The prototype was first flown on 27 April 1934 powered by an 80 hp (60 kW) Hirth HM 60R inline 4-cylinder engine.

Bücker Bü 131A - The intial production version produced both for civil flying schools (Luftsportverband) and the Luftwaffe. Powered by an 80 hp (60 kW) Hirth HM 60R inline 4-cylinder engine. Heavily exported with Switzerland and Japan both acquiring licences for production.

Bücker Bü 131B - An improved version with a 105 hp (78 kW) Hirth HM 504A-2 inline 4-cylinder air-cooled piston engine which added about 8 mph (12.9 km/h) to the top speed and gave a much improved rate of climb.

Bücker Bü 131C - A single experimental version powered by a 90 hp (67 kW) Cirrus Minor inline 4-cylinder engine. Flight testing showed no real performance gain so further work was abandoned.

Tatra T-131 - This aircraft was produced in Czechoslovakia during the war under licence based on the Bücker Bü 131B design.

Type 4 Primary Trainer (Ki-86A) - Produced in Japan by Kokusai under licence for the Japanese Army based on the Bücker Bü 131A design (1,037 aircraft).

Navy Type 2 Primary Trainer Model 11 (K9Wl) - Produced in Japan by Watanabe (later Kyushu) under licence for the Japanese Navy based on the Bücker Bü 131A design (217 to 339 aircraft - exact figures are unknown).

Aero C.4 - Built by Aero in Czechoslovakia during the 1950s.

Specifications (Bücker Bü 131B Jungmann "Young Man")

Type: Two Seat Primary Trainer & Auxiliary Ground Attack

Accommodation/Crew: Pilot/Instructor and Student sitting in open cockpits in tandem with dual controls.

Design: Swedish Designer Anders J. Andersson as Chief Engineer of Bücker Flugzeugbau GmbH. (Formerly from Svenska Aero AB in Stockholm).

Manufacturer: Bücker Flugzeugbau GmbH formed in October 1933 at Johannisthal with Carl Clemens Bücker as Managing Director and owner of the Company. In 1935 the company was moved to a new factory at Rangsdorf, near Berlin. Carl Clemens Bücker was the former Managing Director of Svenska Aero AB in Stockholm. Also licence built by CASA at Cadiz, Spain and by Dornier at Altenrhein, Switzerland. Watanabe (later Kyushu) and Kokusai also built the type under licence in Japan.

Powerplant: One 105 hp (78 kW) Hirth HM 504A-2 inline 4-cylinder air-cooled piston engine.

Performance: Maximum speed 114 mph (183 km/h) at sea level; cruising speed 106 mph (170 km/h); service ceiling 9,840 ft (3000 m); landing speed 51 mph (82 km/h); climb to 6,560 ft (2000 m) in 12 minutes.

Fuel Capacity: A single welded Aluminium fuel tank in the fuselage with a capacity of 11 Imperial gallons (50 litres).

Range: 404 miles (650 km) with internal fuel.

Weights & Loadings: Empty 836 lbs (380 kg) with a maximum take-off weight of 1,474 lbs (670 kg) and a disposable load of 638 lbs (290 kg). Wing loading 9.49 lbs/sq ft (46.3 kg/sq m); power loading 13.75 lbs/hp (6.25 kg/hp).

Dimensions: Span 24 ft 3 1/4 in (7.40 m); length 21 ft 8 in (6.60 m); height 7 ft 4 1/2 in (2.25 m); wing area 145.32 sq ft (13.50 sq m).

Armament: None.

Variants: Bü 131A, Bü 131B, Bü 131C, Tatra T-131 (Czech built), Ki-86A, (Japanese Army), K9W1 (Japanese Navy). C.4 (Postwar Czech version built by Aero)

Equipment/Avionics: Standard communications equipment only.

Wings/Fuselage/Tail Unit: The wings are of the single bay biplane type with interchangeable upper and lower wings. Incidence (lower) 0°, (upper) 1°. Dihedral (lower) 4.5°, (upper) 2.5°. Sweepback 11°. No lift or anti-lift wires attached to lower rear spars. "I" section wooden spars, wooden ribs and conventional drag bracing, all with fabric covering. Steel struts with ailerons on all four wings. The fuselage was of welded chrome-molybdenum steel tube construction with fabric covering, with the exception of metal sheeting used around the engine and cockpit. The tail unit was also of welded chrome-molybdenum steel tube construction with fabric covering with wire bracing. Divided elevator with trimming flaps in trailing-edges and an unbalanced rudder. The aircraft was stressed to an immensely strong +/- 12 g's and was a superb aerobatic aircraft with excellent handling qualities.

Landing Gear: The landing gear was of the divided type. Shock Absorbers with steel springs and oil-damping were hinged to the sides of the fuselage with the axles hinged to a pyramidal structure beneath the structure. Balloon type tires equipped with brakes. Sprung tailwheel.

History: First flight (D-3150 prototype) 27 April 1934; first delivery (Luftsportverband) late 1934; first delivery (Luftwaffe) 1935.