Ivchenko AI-20

Ivchenko AI-20

Company type	Aircraft engine
Industry	Aerospace
Founded	1950s, USSR
Founder	Oleksandr Heorhiiovych Ivchenko (design team leader)
Headquarters	Zaporizhzhia , USSR
Products	Turboprop engines (AI-20 series)
Parent	Ivchenko design bureau

Template:Infobox aero engine The Ivchenko AI-20 (Russian: Ивченко АИ-20) represents a Soviet-era turboprop engine engineered by the Ivchenko design bureau during the 1950s. It was produced extensively and powered aircraft such as the Antonov An-12 cargo plane and the Ilyushin Il-18 passenger airliner.

Design and development

The AI-20 marked the inaugural gas turbine project from the design team headed by Oleksandr Heorhiiovych Ivchenko at the Zaporizhzhia facility in the USSR. Prior to this, their focus had been on smaller piston radial engines like the Ivchenko AI-14 and AI-26. This engine was conceived as a potential propulsion system for large aircraft including the four-engine Ilyushin Il-18 airliner and the Antonov An-10, competing against the Kuznetsov NK-4 engines. While both engine types underwent testing on an initial batch of twenty pre-production Il-18s, full-scale production ultimately favored the Ivchenko design, possibly influenced by an NK-4 engine failure resulting in a crash, as well as strategic considerations to manufacture engines for the Ukrainian An-10 domestically.

The Il-18B variant was equipped with four AI-20A Series 1 turboprops, each delivering a maximum takeoff output of 2,985 kW (4,000 shp) and a continuous cruise power of 2,090 kW (2,800 shp). Although early Il-18A models initially utilized Kuznetsov NK-4 engines, these were soon replaced by AI-20 units. Subsequent Il-18B production incorporated AI-20A Series 2 engines, maintaining similar power specifications but featuring technical enhancements; earlier aircraft were retrofitted accordingly. These engines drove four-bladed variable-pitch reversible propellers measuring 4.5 meters (14 feet 9 inches) in diameter, equipped with noticeable spinners and hydraulically controlled pitch adjustment. Positioned above the wings, the engines included integrated fire suppression systems. Engine starts were performed using electric motors powered by external ground carts.

Structurally, the AI-20 is a single-shaft turboprop featuring a ten-stage axial compressor coupled with a three-stage power turbine, designed to maintain constant operational speed. Early production models suffered from limited reliability, with time between overhauls (TBO) ranging from 600 to 750 hours. The introduction of the AI-20K variant improved this figure significantly to a TBO of 2,000 hours—modest by current standards but considerable at that time. Noise levels remained a persistent issue due to inherent turboprop characteristics, affecting passenger comfort. Initial overhaul intervals were notably short compared to Western contemporaries; however, ongoing development extended TBO to 8,000 hours and service life reached up to 22,000 hours in the AI-20D series 5M.

Mass production commenced in 1958 at Zaporizhzhia's Motor Sich plant and the Perm Engine Plant (UEC-Perm Engines) within the USSR. The engine was also manufactured under license in China as the WJ-6. Approximately 14,000 units of the AI-20 have been produced overall.

Variants

AI-20A series 1

The earliest production model designed for the initial IL-18, delivering 2,985 kW (4,000 shp). The time between overhauls (TBO) was notably low, ranging from 200 to 400 hours.

AI-20A series 2

An enhanced production version maintaining the same power output but incorporating technical upgrades; older aircraft were retrofitted with these Series 2 engines. Despite improvements, TBO remained limited at 600 to 750 hours.

AI-20K

This variant focused on boosting reliability and longevity, resulting in a significantly increased TBO of up to 2,000 hours. It became the primary production model.

AI-20M

Representing a major advancement over previous models, the AI-20M increased takeoff power from 2,985 kW (4,000 shp) to 3,169 kW (4,250 shp), enhancing takeoff capability in "hot and high" environments and enabling greater takeoff weights. It also achieved higher continuous power ratings (2,700 shp), promoting more efficient cruising. Additionally, this version offered improved reliability, reduced weight, and notably better specific fuel consumption (SFC).

AI-20D

This iteration delivered a substantial power increase along with slight improvements in fuel efficiency. Often referred to as AI-20D series 4, it featured an uprated power output of 5,180 shp.

AI-20D series 5

Building upon the achievements of the series 4 variant, this model preserved most performance characteristics while significantly enhancing reliability and durability. The TBO was extended to 6,000 hours with a service life reaching 20,000 hours.

AI-20D series 5M or AI-20DM

The final development in this line closely resembles the AI-20D series 5 but operates at a reduced power setting of 4,750 shp for takeoff. This derating extends engine longevity and increases TBO to 8,000 hours, with an overall service life of up to 22,000 hours.

AI-20

• Antonov An-8
• Antonov An-10
• Antonov An-12
• Antonov An-32
• Beriev Be-12
• Ilyushin Il-18
• Ilyushin Il-38
• Tupolev Tu-4 (KJ-1 AEWC)

WJ-6

• Shaanxi Y-8
• Shaanxi Y-9
• Qing-6 (Chinese upgraded Be-6 airframe)
• AVIC AG600 amphibian
• Xi'an KJ-600 carrier onboard delivery

Specifications (AI-20D series 5)

|ref=Jane's All The World's Aircraft 1993–94, Motor Sich website, Aircraft engines of the World 1970 |type=Single-shaft turboprop |length=3,096 mm (121.9 in) |diameter=450 mm (18 in) (intake casing)

• Width: 842 mm (33.1 in)
• Height: 1,180 mm (46 in)

|weight=1,040 kg (2,290 lb) |compressor=10-stage axial compressor equipped with four bypass valves for starting and transient conditions |combustion=Annular chamber containing ten burner cones |turbine=Three-stage axial flow |fueltype=Aviation kerosene such as JP-4 |oilsystem=Pressure-fed fully recirculating system |power=3,170 kW (4,250 shp) takeoff power at sea level running at 12,300 rpm / (2,900 kW (3,900 shp) + 2.35 kN (529 lbf))

• Maximum cruise power: 2,600 kW (3,500 shp) at 630 km/h (390 mph; 340 kn) altitude 8,000 m (26,000 ft)

• Operating engine speed: 12,300 rpm
• Ground idle speed: 10,400 rpm

|thrust= |compression=7.6:1 during takeoff rising to 9.2:1 for cruise |bypass= |aircon=20.7 kg/s (46 lb/s) at full operating rpm |turbinetemp=TIT maximum of 1,170 K (900 °C) at sea level; JPT temperature 833 K (560 °C) |fuelcon= |specfuelcon=

• Specific fuel consumption at takeoff: 0.322 kg/kWh (0.529 lb/(hp⋅h))
• Specific fuel consumption at cruise: 0.264 kg/kWh (0.434 lb/(hp⋅h))

|power/weight=3.07 kW/kg (1.87 shp/lb) based on equivalent takeoff power |thrust/weight= }

External links

• Motorsich Archived 2014-03-25 at the Wayback Machine