Isotta-Fraschini Delta

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

Although the air-cooling might be considered an anachronism even during the 1930s, 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.

pecifications (Isotta Fraschini Delta R.C.35 IS)

pistonspecs

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.)
weight=510 kg (1,111 lb)
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
fuelsystem=4*Isotta Fraschini downdraft carburetors
fueltype=80/87 octane petrol (aviation gasoline)
oilsystem=dry sump, 2 scavenging, 1 pressure pump
coolingsystem=Air-cooled
power= 770hp/2600rpm take off, 750hp/2600rpm/4000meters. Reduction gear ratio 0.64:1
specpower=0.75 hp/in³ (34.1 kW/L)
compression=6.4:1
fuelcon=
specfuelcon= 270 grams/hp*hour maximum, 250 grams/hp*hour cruise (70%)
oilcon=
power/weight=1.485 hp/kg (0.67 hp/lb)

Uses

* Ambrosini SAI.107
* Ambrosini SAI.207 prototype
* Ambrosini SAI.403 prototype
* Caproni Ca.310 series
* Caproni Ca.331
* Caproni Campini N.1 prototype
* Caudron C.714 (C.760) prototype
* Henschel Hs 129 prototype
* Reggiane Re.2001 prototype