From Wikipedia, the free encyclopedia
Alfa Romeo built/designed a range of aircraft engines based on the
Bristol Jupiter and
Bristol Pegasus designs, designated Alfa 125 , Alfa 126 , Alfa 127 , Alfa 128 , Alfa 129 and Alfa 131 . All these essentially similar engines were mainly fitted to Italian bombers in World War II, Alfa Romeo building around 11,000 units between 1934 and 1944
[1]
Design and development
Alfa Romeo adapted the Jupiter / Pegasus (which are very closely related) to metric measurements, local materials and indigenous equipment.
Variants
Alfa Romeo 131, 9-cyl radial engine.
(The Italian engine designation system includes a suffix indicating major components or attributes. The most common were R for Riduttore - reduction gear and C for Compressore - compressor/supercharger, followed by a number indicating the rated altitude in hundreds of metres, two speed superchargers were indicated by a double figure such as 10/34).
Alfa Romeo Jupiter
The standard 313 kW (420 hp) Jupiter engine built under licence from the
Bristol Aeroplane Company .
Alfa 125 R.C.10
rated at 1,000 m (3,300 ft)
Alfa 125 R.C.35
1934 — 485 kW (650 hp) rated at 3,500 m (11,500 ft)
Alfa 126 R.C.10
1935 — Civilian version of 126 R.C.34 559–597 kW (750–801 hp) rated at 1,000 m (3,300 ft)
Alfa 126 R.C.32
rated at 3,200 m (10,500 ft)
Alfa 126 R.C.34
1935 — 507–582 kW (680–780 hp) rated at 3,400 m (11,200 ft)
Alfa 127 R.C.50
rated at 5,000 m (16,000 ft)
Alfa 127 R.C.55
1937 — 560 kW (750 hp) rated at 5,500 m (18,000 ft)
Alfa 128 R.C.18
641–717 kW (860–962 hp) rated at 1,800 m (5,900 ft)
Alfa 128 R.C.21
1938 — 708 kW (949 hp) rated at 2,100 m (6,900 ft)
Alfa 129 R.C.32
rated at 3,200 m (10,500 ft)
Alfa 131 R.C.14/50
1943 — Two speed supercharger, rated at 1,400 m (4,600 ft) in low gear and 5,000 m (16,000 ft) in high gear.
Applications
Specifications (Alfa 128 R.C.21)
Data from Aircraft Engines of the World 1945
[6]
Archivio Storico Alfa Romeo - Volume II
[7]
General characteristics
Type: 9-cylinder air-cooled radial engine
Bore : 146 mm (5.75 in)
Stroke : 190 mm (7.48 in)
Displacement : 28.6 L (1,745.28 cu in)
Length: 1,329 mm (52.3 in)
Diameter: 1,400 mm (55.1 in)
Dry weight : 516 kg (1,138 lb)
Frontal Area: 1.54 m2 (16.6 sq ft)
Components
Valvetrain : 2 x inlet valves and 2 x exhaust valves per cylinder operated by pushrods and rockers
Supercharger : Gear-driven 1-speed, 8.8:1 ratio, supercharger
Fuel system: 1 x Mona-Hobson AVT85MC updraught carburettor with automatic boost control
Fuel type:
87 octane
Oil system: 551.6 kPa (80 psi),
dry sump .
Cooling system: Air-cooled
Reduction gear : Epicyclic bevel reduction gear, 0.65:1 ratio.
Starter: Garelli compressed air starter
Ignition: 2 x Marelli MF9 magnetos, 2 x spark plugs per cylinder, fed by a shielded harness.
Performance
Power output: Take-off: 708 kW (950 hp) at 2,300 rpm with 1,000 mm (39.37 in) Hg boostMilitary: 641 kW (860 hp) at 2,300 rpm at 2,100 m (6,900 ft)Cruising: 492 kW (660 hp) at 1,800 rpm at 2,500 m (8,200 ft)
Specific power : 24.57 kW/L (0.54 hp/cu in)
Compression ratio : 7:1
Specific fuel consumption : 0.31 kg/kW/hr (0.51 lb/hp/hr) (take-off)
Oil consumption: 0.0078 kg/kW/hr (0.013 lb/hp/hr)
Power-to-weight ratio : 0.782 kW/kg (0.775 hp/lb)
See also
Comparable engines
Related lists
References
Notes
Bibliography
Wilkinson, Paul H. (1945). Aircraft engines of the World 1945 (2nd ed.). New York: Paul H. Wilkinson. pp. 288–289.
Archivio Storico Alfa Romeo - Volume II. Torino, November 1998