Now, it's bringing them back with the CFM Rise, promising 20% fuel savings. Unducted fans (UDFs), also known as propfans or open rotor engines, first popped up in the 1970s. They look a little odd ...

CFM International’s new push to develop an ... Meanwhile, GE designed a competing engine called an “Unducted Fan” – a “gear-less, counter-rotating pusher system” designed to be mounted ...

ultra-high bypass unducted fan engine to cut fuel burn by 25% in about 2025. Momentum increased in 2008 when CFM decided to "put a stake in the ground" by committing to develop a ducted Leap X ...

CFM believes the move to an open rotor will ... RISE builds on earlier unducted fan development work by GE and Safran that dates back to the 1980s, as well as more recent work with research ...

Some called it a propfan, others an unducted fan or open rotor ... engine meet current and anticipated noise regulations, says CFM. There has been concern about what would happen if a propfan ...

unducted fan blades are much noisier than ducted fan blades. The CFM RISE engine, however, takes a totally new approach to open fan design. Instead of the established concept of each open fan ...

Credit: CFM CFM International joint venture partners ... to pave the way for a new generation of fuel-efficient unducted—or open fan—engines to enter service around the mid-2030s.