The
Short S.25 Sunderland was a British
flying boat patrol bomber, developed and constructed by
Short Brothers for the
Royal Air Force (RAF). The aircraft took its service name from the town (latterly, city) and port of
Sunderland in
North East England.
Developed in parallel with the civilian
S.23 Empire flying boat, the flagship of
Imperial Airways, the Sunderland was developed specifically to conform with the requirements of British
Air MinistrySpecification R.2/33 for a long-range patrol/reconnaissance flying boat to serve with the
Royal Air Force (RAF). As designed, it served as a successor to the earlier
Short Sarafand flying boat. Sharing several similarities with the S.23, it featured a more advanced aerodynamic hull and was outfitted with various offensive and defensive armaments, including
machine gun turrets,
bombs,
aerial mines, and
depth charges. The Sunderland was powered by four
Bristol Pegasus XVIII radial engines and was outfitted with various detection equipment to aid combat operations, including the
Leigh searchlight, the
ASV Mark II and
ASV Mark III radar units, and an
astrodome.