Isotta Fraschini Delta

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

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

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

Specifications (Delta R.C.35IS)

Data from

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

See also

Comparable engines

Related lists

References

  1. Gunston 1989, p.82.

Bibliography

  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
  • Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1989. ISBN 0-517-67964-7
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