Sales in the United Kingdom of the American-engined Auster J/2 Arrow were limited by import restrictions on the engines, so Auster re-engined the aircraft with a British engine, the 90 hp Blackburn Cirrus Minor I. The first aircraft flew towards the end of 1946. The two-seat aircraft proved less popular than the companies three-seat Auster J/1 Autocrat and only 27 aircraft were built. A number of aircraft were exported to Australia and these were known as the Archer in that country.[1]
Two J4 airframes (G-AIPH & G-AIJT) were modified with Continental O-200 engines in the late 1960s by the Rolls-Royce employees “Merlin Flying Club”. G-AIJT remains airworthy.
Fuel capacity: Fuel:15 imp gal (18 US gal; 68 L) in fuselage fuel tank, with 13.75 imp gal (16.51 US gal; 62.5 L) under-fuselage auxiliary tank; Oil:2 imp gal (2.4 US gal; 9.1 L) aft of engine.
Powerplant: 1 × Blackburn Cirrus Minor I 4-cylinder inverted air-cooled in-line piston engine, 90 hp (67 kW) maximum at 2,600rpm