The Piaggio P.XII was an Italian 18-cylinder radial aircraft engine developed in the 1930s by the aeronautical manufacturing company Rinaldo Piaggio S.p.A. . The engine was used in many Italian aircraft from 1940 until the end of World War II. An up rated version was produced as the Piaggio P.XXII.
Variants of the Piaggio P.XII include: (R - Riduttori - reduction gearing and C - Compressore - supercharged)
P.XII R.C.35
(geared, rated altitude 3,500 m (11,500 ft))
P.XII R.C.40
(geared, rated altitude 4,000 m (13,000 ft))
P.XII R.C.l00/2v
(geared, rated altitude 10,000 m (33,000 ft))
P.XV R.C.60/2v
(geared, rated altitude 6,000 m (20,000 ft))
P.XXII R.C.35D
Higher rating with slightly higher displacement than the P.XII series engines. (geared, rated altitude 3,500 m (11,500 ft))
P.XXII R.C.35R
Same as P.XXII R.C.35D, but propeller rotates in opposite direction
P.XXII R.C.60
(geared, rated altitude 6,000 m (20,000 ft))
CANT Z.1015
CANT Z.1018
CANT Z.511
Caproni Ca.169
Piaggio P.108
Savoia-Marchetti SM.84ter
Savoia-Marchetti SM.89
Data from Aircraft Engines of the World 1945.
Type: 18-cylinder air-cooled radial engine
Bore: 146 mm (5.75 in)
Stroke: 176 mm (6.93 in)
Displacement: 53 l (3,200 cu in)
Length: 1,700 mm (66.93 in)
Diameter: 1,410 mm (55.51 in)
Dry weight: 850 kg (1,874 lb)
Frontal Area: 1.56 m2 (16.8 sq ft)
Valvetrain: 2 x overhead valves per cylinder operated by rockers and pushrods
Supercharger: Centrifugal compressor, geared to 7.81:1
Fuel system: Single Piaggio downdraught carburettor with automatic boost and mixture control
Fuel type: 87 octane
Oil system: Pressure fed at 482.6 kPa (70 psi), dry sump
Cooling system: Air
Reduction gear: Epicyclic reduction gear, gear ratio: 0.62:1
Starter: Garelli compressed air starter
Ignition: 2x Marelli AQ18 magnetos, 2 x spark plugs per cylinder fed by a shielded ignition harness.
Power output:
Take-off: 1,500 hp (1,100 kW) at 2,100rpm
Military: 1,350 hp (1,010 kW) at 2,100rpm at 3,500 m (11,500 ft)
Cruising: 1,000 hp (750 kW) at 1,700rpm at 3,500 m (11,500 ft)
Specific power: 22.29 kW/l (0.49 hp/cu in)
Compression ratio: 6.5:1
Specific fuel consumption: 0.2795 kg/kW/hr (0.46 lb/hp/hr)
Oil consumption: 0.0134 kg/k/w/hr (0.022 lb/hp/hr)
Power-to-weight ratio: 1.324 kW/kg (0.8 hp/lb)
