In 1931, the Japanese Navy placed an order with the Heinkel aircraft company for a two-seat dive bomber capable of carrying 250 kg (550 lb) of bombs, stressed for catapult launches, and capable of using either wheeled or float undercarriages.
A prototype , the Heinkel He 50aW , was completed in the summer of 1931. It was a biplane of mixed construction. The aircraft had twin-floats for an undercarriage and was powered by a Junkers L5 inline engine. The engine was found to be underpowered. A second prototype, the He 50aL, was built, which was powered by a Siemens Jupiter VI radial engine and had a wheeled undercarriage. A second He 50aL was built and re-designated He 50b. Based on the He 50b, a third prototype designated Heinkel He 66 was completed for the Japanese Navy, and used as the basis of the Aichi D1A.
The He 50 was an equal- span biplane based on a rectangular-section fuselage with a primary structure of welded steel tube construction, faired out to an oval shape by wooden formers and stringers and covered with fabric except in the extreme nose, which was skinned in light alloy. The wings were fabric-covered wooden construction with a marginal stagger and very slight sweep , carrying ailerons on all four panels.
The He 50aL was re-designated He 50 V1 and demonstrated to the German Defence Ministry in 1932.
In spring 1943, following the success of the Soviet VVS's Night Witches units against the Wehrmacht Heer 's frontline encampments while flying their Polikarpov Po-2 biplanes on nocturnal harassment raids, surviving He 50s were rounded up from training schools and delivered to night ground attack units operating on the Eastern Front. The He 50 was used to conduct night harassment sorties on the Eastern Front until September 1944, when the units were disbanded.
Crew: 2 (pilot, observer/gunner)
Length: 9.6 m (31 ft 6 in)
Wingspan: 11 m (37 ft 8¼ in)
Height: 4.5 m (14 ft. 9¾ in)
Wing area: 34.8 m² (374.59 ft²)
Empty weight: 1,600 kg (3,528 lb)
Loaded weight: 2,620 kg (5,778 lb)
Powerplant: 1 × Bramo 322 B (SAM 22B) radial engine , 485 kW (650 hp)
Maximum speed: 235 km/h (127 kn, 146 mph)
Cruise speed: 190 km/h (103 kn, 118 mph)
Range: 1,000 km (621 mi)
Service ceiling: 6,400 m (20,998 ft)
Rate of climb: 250 m/min (820 ft/min)
Armament: 1 × 7.92 mm (0.312 in) MG 15 machine gun for rear seat.
Up to 250 kg (551 lb) bomb load.