Design was begun in the late summer of 1936. A notable feature of the aircraft was the streamlined fuselage, with no protruding canopy-enclosed crew accommodation existing anywhere along the exterior, but instead an extensively glazed cockpit forming the nose itself, heavily framed with many diagonally braced windows immediately behind the propeller spinner's rear edge. Two of the three man crew sat on either side of the driveshaft that was linked to a coupled "power system" pair of Daimler-Benz DB 601 engines, forming a drive unit known as the DB 606.
The DB 606 was installed in the fuselage, just behind the aft wall of the cockpit near to the center of gravity with an enclosed extension shaft passing through the centerline of the cockpit to drive a large four-blade variable-pitch airscrew in the extreme nose. A surface evaporation cooling system was used on the He 119 V1, with the remaining prototypes receiving a semi-retractable radiator directly below the engine system to augment engine cooling during take-off and climb.
Only eight prototypes were completed and the aircraft did not see production mainly because of the shortage of Daimler-Benz DB 601 engines. The first two prototypes were built as land planes with retractable landing gear. The third prototype, He 119 V3, was constructed as a seaplane with twin floats. This was tested at the Travemünde naval seaplane station and was scrapped in 1942 at Marienehe.
On 22 November 1937, the fourth prototype, He 119 V4, made a world class record flight in which it recorded an airspeed of 505 km/h (314 mph), with a payload of 1,000 kg (2,200 lb), over a distance of 1,000 km (620 mi). The four remaining prototypes were completed during the spring and early summer of 1938, the He 119 V5 and V6 being A-series production prototypes for the reconnaissance model, and the He 119 V7 and V8 being B-series production prototypes for the bomber model.
These four aircraft were three-seaters with a defensive armament of one 7.92 mm (.312 in) MG 15 machine gun in a dorsal position, the V7 and V8 having provision for a normal bombload of three 250 kg (550 lb) bombs or maximum bombload of 1,000 kg (2,200 lb). Eventually, the V7 and V8 were sold to Japan in May 1940 and the remaining prototypes served in the role of engine test-beds, flying with various versions of the DB 606, DB 610 (twinned DB 605s), and DB 613 (twinned DB 603) double engines.
Length: 14.80 m (48 ft 6½ in)
Wingspan: 15.90 m (52 ft 2 in)
Height: 5.40 m (17 ft 8½ in)
Wing area: 50.02 m² (538.2 ft²)
Empty weight: 5,201 kg (11,464 lb)
Loaded weight: 7,581 kg (16,678 lb)
Powerplant: 1 × Daimler-Benz DB 606A-2 24-cylinder liquid cooled coupled engine, 1,753 kW (2,350 hp)
Maximum speed: 591 km/h (319 knots, 367 mph) at 4,500 m (14,765 ft)
Cruise speed: 510 km/h (276 knots, 317 mph) at 4,500 m (14,765 ft) (60% power)
Range: 3,123 km (1,687 nmi, 1,940 mi) at 6,000 m (19,685 ft)
Service ceiling: 8,500 m (27,890 ft)
Climb to 2,000 m (6,560 ft): 3.1 min
Climb to 4,500 m (19,685 ft): 10.7 min
Guns: 1 × 7.9 mm (.312 in) MG 15 machine gun in dorsal position