SIAI S.51

The SIAI S.51, Savoia Marchetti S.51 or Savoia S.51 was an Italian racing flying boat built by SIAI for the 1922 Schneider Trophy race.

Design and development
The S.51 was a single-seat sesquiplane flying boat. It was powered by a single 300 hp Hispano-Suiza 8F V8 engine, mounted on two N struts above the hull and below the upper wing, which drove a two-bladed propeller in a pusher configuration. The inclined interplane struts were mounted in a V configuration. The lower wings had small stabilizing floats mounted on inclined struts so that they hung below and outboard of the outer tips of the lower wing.

SIAI later based the design of the hull of its S.58 flying boat fighter of 1924 on that of the S.51's hull.



Operational history
Italy entered the S.51 in the 1922 Schneider Trophy race along with two Macchi M.17 flying boats in competition with a British Supermarine Sea Lion II flying boat. The race was held at Naples on 12 August.

The S.51 capsized in an accident during the seaworthiness trials before the race. Righted by its crew, it completed the race, piloted by Alessandro Passaleva but could only take second place, with the Sea Lion a comfortable 2 min 22 s ahead. The course required 13 laps, a total distance of 370 km, over which the S.51 averaged 229.57 km/h.

On 28 December 1922 the S.51, flown again by Passaleva, set a world speed record for seaplanes of 280.155 km/h.

Operators

 * Kingdom of Italy