Isotta Fraschini Delta

Delta
Preserved Delta RC131
Type	V-12 piston engine
Manufacturer	Isotta Fraschini
First run	1927
Number built	c.3,300

The Delta was a 12-cylinder inverted-V aircraft engine built by Isotta Fraschini prior to and during World War II.^[1]

Design and development[]

The Delta is a fairly rare example of a large air-cooled inline engine, which normally have cooling problems with the rearmost cylinders. It produced about 750 hp in common versions, although others were rated up to 900 hp. The Delta was not widely used, although it could be found on a number of production aircraft and some advanced prototypes.

The engine included a number of otherwise advanced features. For instance, the valves were powered by dual overhead cams driven by power shafts at the rear of the engine. Exhaust ports were arranged to exit toward the middle of the engine, one cylinder bank being the mirror of the other, allowing the piping to be ganged below the engine nacelle.

Variants[]

Delta R.C.20/55 ID-IS

Delta R.C.21/60

Delta R.C.35

Delta R.C.35 I

Delta R.C.35 IS

Delta R.C.40 IS

Delta R.C.40 ID-IS

Delta R.C.48

Delta III R.C.40

Delta IV R.C.17/50

Applications[]

• Ambrosini SAI.107
• Ambrosini SAI.207 prototype
• Ambrosini SAI.403 prototype
• CANT Z.515
• Caproni Ca.313
• Caproni Ca.314
• Caproni Ca.331
• Caudron C.714 (C.760) prototype
• Henschel Hs 129 prototype
• Reggiane Re.2001 prototype
• Savoia-Marchetti SM.86

Specifications (Delta R.C.35IS)[]

Data from^{[citation needed]}

General characteristics

• Type: 12-cylinder air-cooled 60 degree inverted vee
• Bore: 132 mm (5.197 in)
• Stroke: 160/165 mm (6.299/6.496 in), with main and articulated rod
• Displacement: 26.685 Litres (1,628.44 in³)
• Length: 2000 mm (78.8 in.)
• Width: 840 mm (33.07 in.)
• Height: 883 mm (34.76 in.)
• Dry weight: 510 kg (1,111 lb)

Components

• Valvetrain: 2 Poppet valves per cylinder, sodium cooled exhaust valves, double overhead camshafts.
• Supercharger: single stage single speed centrifugal type supercharger, gear ratio 9.8:1
• Fuel system: 4*Isotta Fraschini downdraft carburetors
• Fuel type: 80/87 octane petrol (aviation gasoline)
• Oil system: dry sump, 2 scavenging, 1 pressure pump
• Cooling system: Air-cooled

Performance

• Power output: 770hp/2600rpm take off, 750hp/2600rpm/4000meters. Reduction gear ratio 0.64:1
• Specific power: 21.5 kW/L (0.47 hp/in³)
• Compression ratio: 6.4:1
• Specific fuel consumption: 270 grams/hp*hour maximum, 250 grams/hp*hour cruise (70%)
• Power-to-weight ratio: 1.485 hp/kg (0.67 hp/lb)

See also[]

Comparable engines

• Argus As 410
• de Havilland Gipsy Twelve
• Ranger V-770
• Walter Sagitta

Related lists

• List of aircraft engines

References[]

Wikimedia Commons has media related to Isotta Fraschini Delta.

Bibliography[]