Progress D-27

The Progress D-27 is a three-shaft propfan engine developed by Ivchenko Progress, and manufactured by Motor Sich in Ukraine. The gas generator was designed using experience from the Lotarev D-36 turbofan. The D-27 engine was designed to power more-efficient passenger aircraft such as the abandoned Yakovlev Yak-46 project, and it was chosen for the Antonov An-70 military transport aircraft. As of 2019, the D-27 is the only contra-rotating propfan engine to enter service.

Design and development
The engine was launched in 1985 by the Ivchenko-Progress Design Bureau for commercial and military transport aircraft. It was designed to meet the expected growth in demand for new aero engines for civil and military applications. It has a take-off rating of 13240 hp for the Antonov An-70. Gunston lists ratings between 13880 and 16250 hp for the engine.

In 1990, the D-27 engine was proposed for the 150-162 seat Yakovlev Yak-46 airliner. This twin-engined derivative of the three-engine Yakovlev Yak-42 would mount the two D-27 engines on the rear fuselage. At the time, the D-27 had a 3.8 m fan, produced 9700 kW at takeoff resulting in a thrust of 11200 kgf, and had a thrust specific fuel consumption (SFC) of 0.47 tsfc at a cruise speed of 850 km/h.



A single prototype of the D-27 engine was used for flight testing on an Ilyushin Il-76 modified as a testbed aircraft since at least 1992, in preparation for use on the Antonov An-70T military transport aircraft. The version of the D-27 for the An-70T produced 10290 kW and now had 4.5 m propellers. In 1993, the Il-76LL testbed with D-27 engine was put on static display at Moscow's MAKS Air Show, and the next year it flew at the ILA Berlin Air Show and the Farnborough Air Show. The testbed configuration made a final appearance at the MAKS Air Show in 1997.

On December 16, 1994, four D-27 engines powered the first An-70 prototype on its maiden flight. This was the first aircraft flight ever to be completely powered by propfan engines. However, the prototype suffered a crash during its fourth flight in February 1995, destroying the aircraft and leaving no survivors. Antonov constructed a second prototype, which made its maiden flight on April 24, 1997 with four new D-27 engines. During its test program, the prototype also flew to the 1997 MAKS Air Show and the 1998 ILA Berlin Air Show.

The D-27's three-shaft gas turbine engine has an axial low-pressure compressor, a mixed-flow high-pressure compressor, an annular combustion chamber, a single-stage high-pressure turbine, and a single-stage low-pressure turbine. The SV-27 contra-rotating propfan, provided by SPE Aerosila, is driven by a four-stage turbine via a shaft connected to a planetary reduction gear which incorporates a thrust meter. The eight-bladed front propeller receives most of the engine power output and provides most of the thrust, while the back propeller has only six blades. The propellers rotate at 1,000 revolutions per minute (rpm) at takeoff and 850 rpm at cruise. The engine has an overall thermal efficiency of 37 percent.

On December 23, 2005, Antonov announced that the An-70-100 was awarded a noise certificate stating that the D-27-powered aircraft met Stage 3 noise regulations, which permitted international airlines to fly the aircraft unrestricted. In response to the US Stage 4 civil noise regulations adopted in 2006, the engine was modified in 2007 to reduce noise by increasing the separation between the front and back propellers. A further noise-related change in propeller spacing was made in 2010–2012, resulting in a 50-percent increase in separation from 600 to 900 mm.

The Ukrainian armed forces accepted the An-70 with D-27 engines into army service on January 19, 2015.

On September 3, 2019, the Russian navy decided to order Beriev A-42 amphibious aircraft, the development of which had been suspended in 1993. The expectation was that the aircraft would probably use two D-27 propfans as the powerplant. The initial order was for three aircraft, but no timeline was announced. Regardless, the Motor Sich engine manufacturing plant in Zaporizhzhia was destroyed by Russian forces in late May 2022 following the 2022 Russian invasion of Ukraine.

Variants


Ivchenko-Progress worked on derivatives based on the D-27 engine core, mostly within the 1988-1995 time frame. Proposals included the following designs:


 * D-27A: designation of the 14000 hp engines for the Beriev A-42PE jet-powered search and rescue (SAR) amphibious aircraft, which was proposed in 1994.


 * D-27M: a 16000 hp variant.


 * D-127: a turboshaft engine with a rated power of 14500 hp; intended to power the Mil Mi-26M heavy transport helicopter, with production targeted for 1998.


 * AI-127: a helicopter engine with an output rating of 14500 hp, derived from the D-27. The engine has a power SFC of 0.181 kg/hph at takeoff and 0.210 kg/hph at cruise.


 * D-227: an unducted propfan that could be gearless (direct-drive) or geared, with an output rating of 16000 to 17000 hp. This engine was intended for the Antonov An-170, a derivative of the An-70, and it was proposed for the Tupolev Tu-334.




 * D-527: an engine with an ultra-high bypass ratio of 18 that was considered for the Tupolev Tu-334. Nicknamed "super contrafan," the D-527 was ducted and had direct-drive contra-rotating fans mounted at the rear of the engine, like Rolls-Royce's proposed RB529 "Contrafan".


 * D-627: a super-high bypass ratio turbofan engine with a takeoff thrust of up to 11000 kgf. An alternative engine for the Yakovlev Yak-46, the D-627 was designed to have a specific fuel consumption not exceeding 0.5 tsfc at a cruise altitude of 11000 m and a cruise speed of Mach 0.8 (0.8 Mach). The D-627 had coaxial contra-rotating fans with a differential gearbox.


 * D-727: a variant for the commercial version of the An-70, called the An-70T. A high-bypass turbofan engine, the D-727 has a bypass ratio of 12.85. The D-727 was also the powerplant for the Yak-46-1, the high-bypass turbofan version of the Yakovlev Yak-46.


 * AI-727: a range of ultra-high bypass ratio (of nearly 13), geared turbofan engines with a low-noise, wide-chord fan; and thrust between 10000 and 11500 kgf. This engine had a takeoff thrust SFC (TSFC) of 0.257 tsfc and a cruise TSFC of 0.540 tsfc. The engine was offered to power the Antonov An-148T and the Irkut MS-21.

Applications

 * Antonov An-70
 * Antonov An-180 (abandoned)
 * Beriev A-42
 * Ilyushin Il-76 (testbed)
 * Tupolev Tu-334 (rejected)
 * Tupolev Tu-95MS (proposed re-engine)
 * Yakovlev Yak-44 (abandoned)
 * Yakovlev Yak-46 (abandoned)