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 used to power the main reconnaissance aircraft in the Regia Aeronautica, and a number of other aircraft developed in Italy, during the Second Italo-Ethiopian War, Spanish Civil War and Second World War.

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.37
Developed from Gnome-Rhône 9K
Developed into Piaggio P.X


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", all based on the same radial design.[2]


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


Specifications (R.C.40)

Data from S.A. Piaggio e.C. (1939). Instruzione per l’uso del motore P IX R C 40. Rome: Ministero dell’Aeronautica.

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)



  • 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


  1. Angle, Glenn Dale (1939). Aerosphere. New York: Aircraft Publications. p. 584.
  2. Gunston, Bill (1986). World Encyclopedia of Aero Engines. London: Guild Publishing. p. 125.
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