;A.R.9 Mk I :203 horsepower (151 kW). ;A.R.9 Mk II :205 horsepower (153 kW). Higher permissible rpm version of Mk I. ;A.R.9 Aries Mk III :225 horsepower (168 kW), low boost
supercharger fitted. ;Scorpio I :250 horsepower (186 kW), (230 bhp at 2,250 rpm), increased
bore (111mm x 120 mm) to give a displacement of 9,477 cc, increased
compression ratio. Reduction gearing. ;Scorpio II and III :250 horsepower (186 kW), designed to run on 87
octane fuel with 6.5:1 ratio. ;Leo :280 horsepower (209 kW), few details, not flown or produced. ;Libra :390 hp at 6,000 ft. 725 lbs (329 kg). Tested but not flown or produced. ==Applications==