Bucker Bu-131 Jungmann
CASA 1-131
Watanabe and Kyushu Kokusai Ki-86A
Watanabe and Kyushu K9W1

Bücker Flugzeugbau first design, designed by Anders Andersson, was the Bü.131A Jungmann powered by a 4 cylinder Hirth in line engine. A light two-seat biplane trainer specially developed for school and other training purposes, the prototype "D-3150" flew first 27 April 1934 with a 60-kW (80-hp) Hirth HM 6CR inline engine. The Jungmann was ordered by the Deutsche Luftsport Verband (The German Air-Sports Association). In 1936, the Luftwaffe adopted the Jungmann as one of its primary trainers.

Power was provided by a 60kW Hirth H.M.60R engine in the Bü.131A and a 78kW Hirth H.M.504A inverted engine in the Bü.131B.

Before the outbreak of World War II the trainer was being used in 21 countries and licence-built in Holland, Czechoslovakia, Spain and Switzerland.

Spain was one of the earliest customers. Over a hundred German-built Jungmanns were delivered to the Spanish Nationalist side in the civil war. A total of 500 Jungmanns were built by the Construcciones Aeronauticas S.A. (CASA) in Spain. The first 200 had German Hirth HM504 engines but the remainder were powered by versions of the Spanish ENMA Tigre G-IV. In Spain production started 1938 and the CASA I-131 remained in production until the end of the fifties. The CASA E3B is a licence-built example.

Some 1,254+ were built in Japan by Watanabe and Kyushu as the army’s Kokusai Ki-86A (1,0371} and the navy’s K9W1 (217+).

Production figures have not survived, but some indication of scale is provided by the fact that Hungary took 100 and Romania 150, while Switzerland built 75. The Bucker Bü.131A Jungmann was also built under license in Switzerland and Czechoslovakia.

Production was boosted by the post-war C.4

Bucker Prado Sl offered kits to build the former German Jungmann two-seat aerobatic biplane using original Bucker/CASA Bu 131 jigs, plus Jungmeister single-seat aerobatic biplane.

Gallery

Engine: 1 x Hirth HM60R, 59kW
Max Take-off weight: 630 kg / 1389 lb
Empty weight: 280 kg / 617 lb
Wingspan: 7.4 m / 24 ft 3 in
Length: 6.7 m / 21 ft 12 in
Height: 2.3 m / 7 ft 7 in
Wing area: 13.5 sq.m / 145.31 sq ft
Max. speed: 170 km/h / 106 mph
Cruise speed: 150 km/h / 93 mph
Ceiling: 3500 m / 11500 ft
Range w/max.fuel: 680 km / 423 miles
Crew: 2

Bu 131B
Engine : Hirth HM 504 A-2, 104 hp, 78kW
Length : 21 ft 8in / 6.62 m
Height: 7.776 ft / 2.37 m
Wingspan : 24 ft 3.25 in / 7.4 m
Wing area : 145.314 sq.ft / 13.5 sq.m
Max take off weight : 1477.4 lb / 670.0 kg
Weight empty : 882.0 lb / 400.0 kg
Max. weight carried :  595.4 lb / 270.0 kg
Max. speed : 93 kts / 173 km/h / 114mph at sea level
Initial climb rate : 748.03 ft/min / 3.8 m/s
Service ceiling : 11483 ft / 3500 m
Wing load : 10.25 lb/sq.ft / 50.0kg/sq.m
Range : 216 nm / 400 km
Endurance : 3 h
Crew: 2