The Fiat 4700 was an Italian turbo-generator developed by Fiat Aviazione under contract to the Italian Defence Ministry and used to power the experimental Fiat 7002 helicopter. The 4700 was a turbo-driven air compressor driven by the primary engine, a turbojet engine based on the Fiat 4002. The compressor and primary engine are mechanically independent. The engine is mounted vertically to reduce the length of the compressed-air ducts to the rotor. First run in 1960, the engine was used on the Fiat 7002 helicopter which first flew on 26 January 1961 where the Fiat 4700 was used to power the cold tip-jets on the two-blade rotor.
Type: Gas generator
Length: 1,300 mm (51.18 in) (height)
Diameter: 612 mm (24.09 in)
Dry weight: 152 kg (335.10 lb)
Compressor: Single-sided centrifugal flow + gas generator single sided centrifugal flow compressor driven by the free power turbine
Combustors: Annular with 16 burners
Turbine: 1-stage axial flow (gas trubine power) + 1-stage axial flow free power turbine (Gas generator power)
Fuel type: Aviation kerosene to MIL-F-5624 (JP-4)
Oil system: Re-circulating pressure system with one pressure pump adnthree scavenge punmps, oil grade DERD 2479.
Maximum power output: 454.88 kW (610 hp) (gas hp for take-off), 376.58 kW (505 hp) (ghp max continuous)
Overall pressure ratio: 4:1
Power-to-weight ratio: 2.99 kW/kg (1.82 hp/lb