Wright's last single-row radial was the R-1300 Cyclone 7, essentially one row of a R-2600. Designed in 1942, the earliest flight I can find is in 1949 powering the XT-28A.
Production was licensed first to Kaiser-Frazer, then to Lycoming.

models

• R-1300-1: 800 hp (596 kW)
• R-1300-3: 700 hp (522 kW)

specifications

• 7 cylinder, air-cooled, radial engine
• displacement: 1,302 cubic inches (21.3 litres)
• bore x stroke: 6.125 x 6.3125 inches

used by

• North American T-28A Trojan
• Sikorsky UH-19 Chickasaw