Sunderland armament protected a heavy patrol load

The Sunderland's nose, dorsal, tail, waist, and later upgraded gun positions gave the relatively slow aircraft unusually extensive self-defence. A maximum speed of about 210 miles per hour made that protection important when patrols brought it within reach of enemy fighters. Its range and endurance were shorter than the Catalina's, but a gross takeoff weight near 26.5 tonnes allowed roughly ten tonnes of stores and payload. The comparison shows that maritime patrol design was not a single contest for maximum radius: survivability and useful load could justify a different balance.