Juhani Heinonen produced the Heinonen HK-4 in 1964 for the Finnish Aeronautical Association.
Heinonen developed the two-seater with an all-wood wing, ailerons fabric covered. The all-wood fuselage has four main longerons and plywood covering. The tail is wood cantilever with fabric covered rudder and elevator. An elevator trim is adjustable from the cockpit.
The landing gear uses cantilever spring steel main legs attached to the wing, and the tail wheel is steerable.
A baggage compartment is behind the seats.
Engine: Lycoming O-235-C1, 115 hp
Wing span: 26 ft 0.5 in
Lengt: 20 ft 2 in
Height: 7 ft 1.5 in
Empty weight: 870 lb
MTOW: 1323 lb
Top speed: 148 mph
Cruise: 127 mph
Service ceiling: 15,400 ft
All Aero 