Development of the basic design continued with the three-seat He 4 and He 5 reconnaissance seaplanes produced in 1926.
A single-engined three-seater with inline separated open cockpits. A monoplane low aerofoil braced under-wing by 4 pairs of masts in N configuration, uniting the two floats in the catamaran and the base of the fuselage. The cantilever horizontal stabilizer was placed directly on the back of the fuselage. Construction wood and fabric covered aerofoil, wood and plywood coating for the fuselage.
The He 4 was powered by the 268kW / 360-hp Rolls-Royce Eagle IX, but it is doubtful whether it was produced in large numbers.
The He 4 was licence-built in Sweden for the Navy by Svenska.

Engine Rolls-Royce Eagle IX, 360 hp
Prop two-bladed wooden fixed Pitch
Wingspan: 17,99 m / 59 ft
Length: 12,50 m / 41 ft
Height: 3,65 m
Wing area: 52,50 sq.m
Empty weight: 1761 kg
MTOW: 2500 kg / 5510 1b
Wing loading: 47,619 kg/sq.m
Power loading: 6,944 kg/hp
Max speed: 180 kmh / 112 mph
ROC: 222 m/min
Landing speed: 87 km/h
Ceiling: 3800 m
Range: 800 km.