Hydraulic power was used for various purposes throughout the Stirling. The nose and dorsal turrets were powered by a duplex pump driven by the inner port engine, while the dorsal turret was powered by a single pump driven by the inner starboard engine. Pulsations in the hydraulic lines were smoothed out by a series of recuperators; German fighter pilots soon learned that by shooting at the area around roundels painted on the fuselage, two of the three turrets could be disabled and the recuperators were moved in later models of the Stirling to reduce their vulnerability.