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SIAI S.51.jpg
Role Racing flying boat
National origin Italy
Manufacturer SIAI
First flight 1922
Primary user Italy
Number built 1

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

Design and development[edit]

The S.51 was a single-seat sesquiplane flying boat. Its 224-kilowatt (300-horsepower) Hispano-Suiza 8A V8 engine, mounted on two N struts above the hull and below the upper wing, 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.[1]

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.[2]

Operational history[edit]

All sources agree that Italy entered the S.51 in the 1922 Schneider Trophy race along with two Macchi M.17 flying boats, and that the three Italian aircraft competed against a British Supermarine Sea Lion II flying boat which won the race. Other than that, sources provide deeply inconsistent and mutually contradictory accounts of the S.51's career.

Some sources[3] claim that the S.51 crashed during the race, killing its pilot.[4] states that the S.51 suffered water damage when it capsized in a pre-race accident and that this damage forced it to retire from the competition after its engine nacelle began to separate from the upper wing during the race; however, this source does not say that the aircraft crashed.[5][6][7] claim that the S.51 finished the race with an average speed of 230.93 kilometers per hour (143.41 miles per hour) and a finishing time of 1 hour 36 minutes 54 seconds, in second place behind the Sea Lion II but ahead of both M.17s.

Some sources claim that the S.51 had a career after the 1922 race. One source[8] states that on 28 December 1922 the S.51 set a speed record for seaplanes of 280.155 kilometers (174.080 mi) per hour, and another[9] claims that Italy considered entering the S.51 in the 1923 Schneider Trophy race but ultimately did not.


 Kingdom of Italy


General characteristics

  • Crew: 1
  • Length: 8 m (26 ft 3 in)
  • Wingspan: 10 m (32 ft 10 in)
  • Height: 2.5 m (8 ft 2 in)
  • Wing area: 23 m2 (250 sq ft)
  • Empty weight: 780 kg (1,720 lb)
  • Gross weight: 1,080 kg (2,381 lb)
  • Powerplant: 1 × Hispano-Suiza 8F (Type 42) V-8 water-cooled piston engine, 220 kW (300 hp)


  • Maximum speed: 280 km/h (174 mph; 151 kn)
  • Cruising speed: 230 km/h (143 mph; 124 kn)

See also[edit]

Related lists


  1. ^ "Artwork of Savoia S.51 by Hideaki Ozawa". Retrieved 2015-11-04. 
  2. ^ Green and Swanborough, p. 527.
  3. ^ Aviation History: Schneider Trophy Races and Vašiček, Aviation History, September 2002, p. 34.
  4. ^ Schneider Trophy Races Archived February 19, 2009, at the Wayback Machine.
  5. ^ "Schneider Trophy 6th Edition August 1922". Retrieved 2012-07-31. 
  6. ^ "Society of Air Racing Historians: Schneider Cup Races". Retrieved 2012-07-31. 
  7. ^ Italian Wikipedia Savoia-Marchetti S.51
  8. ^ "IPMS Racing & Record Aircraft SIG - Record List". Retrieved 2012-07-31. 
  9. ^ Italian Wikipedia Savoia-Marchetti S.51.