The R was a physically imposing engine designed by a team led by Ernest Hives and including Cyril Lovesey, Arthur Rowledge and Henry Royce. The R shared the Buzzard's bore, stroke and capacity, and used the same 60-degree V-12 layout. A new single-stage, double-sided supercharger impeller was designed along with revised cylinders and strengthened connecting rods. The wet-liner cylinder blocks, crankcase and propeller reduction gear castings were produced from "R.R 50" aluminium alloy; and because of the short life expectancy of these engines, forged aluminium was used to replace bronze and steel in many parts.