Piaggio Stella P.IX

The Piaggio P.IX, or Piaggio Stella P.IX, was an Italian nine-cylinder radial aircraft engine produced by Rinaldo Piaggio S.p.A.. Based on the Gnome-Rhône 9K, the engine was rated at 600 hp (447 kW). Production was used to power a number of other aircraft developed in Italy. The main users were the Savoia-Marchetti SM.81 transport and the IMAM Ro.37bis, the main reconnaissance aircraft in the Regia Aeronautica during the Second Italo-Ethiopian War, Spanish Civil War and Second World War, but the engine was also used by other designs, including the prototype Savoia-Marchetti SM.79.

Piaggio P.IX
P.IX mounted on the IMAM Ro.37 at the Italian Air Force Museum, Vigna di Valle
Type Air cooled radial
National origin Italy
Manufacturer Piaggio
Designed by Renzo Spolti
First run 1933
Major applications IMAM Ro.37bis
Savoia-Marchetti SM.81
Developed from Gnome-Rhône 9K
Developed into Piaggio P.X

Design and development

Piaggio acquired a license from Gnome et Rhône in 1925 for their engines derived from the Bristol Jupiter and, in 1933, brought out a developed version, created under the direction of engineer Renzo Spolti.[1] The engine had nine cylinders and was therefore named P.IX. It was one of a range of Piaggio radial engines named Stella, or Star, all based on the same radial design.[2]

The engine had cylinders that had steel barrels and aluminium heads. Aluminium alloy pistons were connected to a split crankshaft via articulated connecting rods. The valves were enclosed.[3] Each cylinder retained the same bore and stroke as the Gnome-Rhône 9K, 146 millimetres (5.7 in) and 165 mm (6.5 in) respectively.[1] However, it was more powerful and was rated at 600 horsepower (447 kW) when fitted with a supercharger.[4]

The engine was used to power aircraft that served during the Second Italo-Ethiopian War, Spanish Civil War and Second World War, including one hundred and forty Savoia-Marchetti SM.81s, a Regia Aeronautica transport, and the majority of the production of the IMAM Ro.37bis reconnaissance aircraft. Most had retired by 1943.[5][6]

Variants
P.IX R.
Normally aspirated and geared.[2]
P.IX R.C.
Supercharged and geared.[2]
P.IX R.C.10
Supercharged and geared, rated at 1,000 m (3,300 ft).[7]
P.IX R.C.40
Supercharged and geared, rated at 4,000 m (13,000 ft).[3]

Applications

Specifications (R.C.40)

Data from Piaggio, 1939[4]

General characteristics

  • Type: 9-cylinder, single row, air cooled radial engine
  • Bore: 146 mm (5.7 in)
  • Stroke: 165 mm (6.5 in)
  • Displacement: 24.9 l (1,519 in3)
  • Length: 1,050 mm (41 in)
  • Diameter: 1,408 mm (55.4 in)
  • Dry weight: 430 kg (950 lb)

Components

Performance

  • Power output:
    • Take-off: 610 hp (455 kW) at 2100 rpm
    • Cruise: 600 hp (447 kW) at 2100 rpm at 4,000 m (13,123 ft)
  • Compression ratio: 6.0:1

See also

Related development

Comparable engines

Related lists

References

Citations
  1. Angle 1939, p. 584.
  2. Gunston 1986, p. 125.
  3. Angle 1941, p. 143.
  4. S.A. Piaggio e.C. 1939.
  5. Passingham 1977, p. 182.
  6. Thompson 1963, p. 199.
  7. Abate & Alegi 1992, p. 245.
  8. Thompson 1963, p. 55.
  9. Thompson 1963, p. 62.
  10. Abate & Alegi 1992, p. 244.
  11. "AP.1". Airwar. Retrieved 3 March 2020.
  12. Green & Swanborough 1994, p. 108.
  13. Fitzsimmons 1971, p. 2217.
  14. Thompson 1963, p. 222.
  15. Thompson 1963, p. 220.
  16. Thompson 1963, p. 258.
  17. Thompson 1963, p. 260.

Bibliography
  • Abate, Rosario; Alegi, Gregory; Apostollo, Giorgio (1992). Aeroplani Caproni: Gianni Caproni and his aircraft, 1910-1983. Trento: Associazione Museo dell'Aeronautica G. Caproni. OCLC 237798156.
  • Fitzsimmons, Barnard (1971). The Illustrated Encyclopedia of 20th Century Weapons and Warfare. 20. New York: Columbia House. OCLC 8842839.
  • Angle, Glenn Dale (1939). Aerosphere. New York: Aircraft Publications.CS1 maint: ref=harv (link)
  • Angle, Glenn Dale (1941). Modern Aircraft Engines. New York City: Aircraft Publications. OCLC 658901703.
  • Gunston, Bill (1986). World Encyclopedia of Aero Engines. London: Guild Publishing. ISBN 978-1-85260-509-4.CS1 maint: ref=harv (link)
  • Passingham, Malcolm (May 1977). "Savoia-Marchetti SM81". Aircraft Illustrated. 10 (5): 182–187.CS1 maint: ref=harv (link)
  • S.A. Piaggio e.C. (1939). Instruzione per l’uso del motore P IX R C 40. Rome: Ministero dell’Aeronautica.CS1 maint: ref=harv (link)
  • Green, William; Swanborough, Gordon (1994). The Complete Book of Fighters: An Illustrated Encyclopedia of Every Fighter Aircraft Built and Flown. New York: SMITHMARK Publishers. ISBN 0-8317-3939-8.CS1 maint: ref=harv (link)
  • Thompson, Jonathon W. (1963). Italian Civil and Military Aircraft 1930–1945. USA: Aero Publishers Inc. ISBN 0-8168-6500-0.CS1 maint: ref=harv (link)
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