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.
Progress D-27
The Progress D-27 engine on the Ilyushin Il-76LL flying testbed at the 1997 MAKS air show.
A front view of two Progress D-27 on the starboard wing of an Antonov An-70 aircraft at the 2013 Paris Air Show.
A back view of two Progress D-27 propfans. The aft propellers have only six blades each, while the front propellers each have eight blades.
A propfan, also called an open rotor engine, open fan engine or unducted fan, is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop. A propfan is typically designed with a large number of short, highly twisted blades, similar to the (ducted) fan in a turbofan engine. For this reason, the propfan has been variously described as an "unducted fan" (UDF) or an "ultra-high-bypass (UHB) turbofan".
A mockup of the GE36 at the Musée aéronautique et spatial Safran
The GE36 on a McDonnell Douglas MD-80 demonstrator at the 1988 Farnborough Air Show. The gearless unducted fan engine had an overall diameter of 11.67 ft (3.56 m), with either eight or ten blades in front (depending on the particular configuration) and eight blades in back.
The Progress D-236 propfan engine on the Yak-42E-LL testbed aircraft at the Paris Air Show in 1991
Progress D27 Propfans fitted to an Antonov An-70
