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The Isotta Fraschini Asso 750 was an Italian W 18 water-cooled aircraft engine of the 1930s. Produced by Isotta Fraschini the engine displaced just under 48 l (2,900 cu in) and produced up to 940 hp (700 kW). Together with the Asso 200 and the Asso 500 the Asso 750 was part of a family of modular engines, that used common and interchangeable components to lower production costs.

Asso 750
Preserved Asso 750
Type	W 18 piston engine
National origin	Italy
Manufacturer	Isotta Fraschini
First run	1934

Technical description

The W-18 Asso 750 had three six-cylinder in-line banks made of chrome-manganese steel, each joined by a single cast aluminum head for each bank of cylinders.

Operational history

A version with an effective power of 940 hp (700 kW) was optimized for the Savoia-Marchetti S.55X used for the trans-Atlantic flight of Italo Balbo.

Variants

Asso 750

Direct-drive, unsupercharged.

Asso 750 R.

Development with modified crankcase and crankshaft, fitted with a 0.658:1 reduction gear. Maximum power output 940 hp (700 kW).

Asso 750 R.C.

Asso 750 R.C.35

The 750 R. fitted with a supercharger, rated altitude of 3,500 m (11,500 ft).

Asso 750 M

A 57.25 l (3,494 cu in) racing development with 150 mm (5.9 in) bore and 180 mm (7.1 in) stroke, for the Macchi M.67, re-designated Asso 1000 Ri.

Applications

• CANT Z.501 (early versions)
• Caproni Ca.111
• Macchi M.C.77
• Savoia-Marchetti S.55
• Savoia-Marchetti S.62
• Savoia-Marchetti S.78

Engines on display

At the Italian Air Force Museum two Isotta Fraschini Asso 750 are exhibited: A direct-drive Asso 750 and an Asso 750 R.C.35 with reduction gear and supercharger.

Specifications (Asso 750)

Data from Il motore Isotta Fraschini Asso 750 [1][2]

General characteristics

• Type: W-18 liquid/water-cooled
• Bore: 140 mm (5.5 in)
• Stroke: 170 mm (6.7 in)
• Displacement: 47.6 l (2,900 cu in)
• Length: 2,196 mm (86.5 in)
• Width: 1,060 mm (42 in)
• Height: 1,060 mm (42 in)
• Dry weight: 630 kg (1,390 lb)

Components

• Valvetrain: Overhead valves 2x inlet and 2x exhaust per cylinder
• Supercharger: No supercharger fitted to this variant: supercharger available in other variants - (R.C.35 rated to 3,500 m (11,500 ft)).
• Fuel type: Gasoline 87 Octane
• Oil system: pressure
• Cooling system: Liquid/water
• Reduction gear: Not fitted to this variant: reduction geared variants available (0.658:1 R. and R.C.35).

Performance

• Power output: Normal 800 hp (600 kW) at 1700 rpm; Take-off 850 hp (630 kW) at 1750 rpm; Max 900 hp (670 kW) at 1900 rpm
• Compression ratio: 5.6:1
• Specific fuel consumption: 0.295 kg/kWh (0.485 lb/(hp⋅h))
• Oil consumption: 0.00114 kg/kWh (0.00187 lb/(hp⋅h))
• Power-to-weight ratio: Normal 0.95 kW/kg (0.58 hp/lb) max 1.129 kW/kg (0.687 hp/lb)

See also

Related lists

• List of aircraft engines

References

Further reading

• Cei, Leoniero; Fiore, Amedeo (1934). Il motorista d'aviazione (in Italian). Milan: Ulrico Hoepli.
• "Jotti da Badia Polesine". Annuario dell'Aeronautica Italiana. Milan.: Libreria Aeronautica: 222. 1934.
• "Foreign Aero Engines at Olympia". Flight. XXI No. 30 (1074): 761–778. 25 July 1929. Retrieved 8 November 2018.

На других языках

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- [en] Isotta Fraschini Asso 750

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[fr] Isotta Fraschini Asso 750

Le moteur Isotta Fraschini Asso 750 est un moteur étudié et mis au point selon un cahier des charges de l'Aeronautica Militare émis en 1924 pour équiper des avions militaires[1]. Il fait partie de la famille de moteurs modulaires créée par le constructeur italien qui comprend l'Asso 200, l'Asso 500 et l'Asso 1000

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[it] Isotta Fraschini Asso 750

L'Isotta Fraschini Asso 750 era un motore aeronautico 18 cilindri a W raffreddato ad acqua, prodotto dalla italiana Isotta Fraschini. Assieme all'Asso 200 e all'Asso 500 faceva parte di una famiglia di motori modulari, ovvero con componenti comuni ed intercambiabili che, grazie a questo, garantivano costi di produzione più contenuti.

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