CFM International RISE
| Company type | Joint venture |
|---|---|
| Industry | Aerospace engineering |
Area served | Global |
| Products | Aircraft engines (including RISE open rotor engine) |
| Owner | GE Aerospace, Safran Aircraft Engines (equal ownership) |
The CFM International RISE (Revolutionary Innovation for Sustainable Engines) represents an open rotor engine currently being developed by CFM International, a joint venture equally owned by American GE Aerospace and French Safran Aircraft Engines. Engineered to operate on both hydrogen and sustainable aviation fuels, this engine is projected to cut fuel consumption and carbon dioxide emissions by approximately 20% compared to previous prototype efforts by SAFRAN, GE Aviation (now GE Aerospace), and other collaborators.
Historical Context
The fuel shortages triggered by the 1973 oil crisis ignited renewed interest in fuel-saving technologies such as open rotor (propfan) engines. Despite this, earlier models failed to reach commercial production largely due to declining oil prices and concerns over noise levels.
Prior to the RISE initiative, both Safran and GE Aviation had conducted experimental work on open rotor engines. Safran carried out ground-based testing in 2019 under the auspices of the European Union's Clean Sky program, while GE performed wind tunnel assessments on a variant of the GE36 engine during the early 2010s with support from the Federal Aviation Administration.
Program Launch
The RISE project was unveiled by CFM International in June 2021 as the planned replacement for the CFM LEAP turbofan, aiming for operational deployment in the mid-2030s. At the 2022 Farnborough Airshow, CFM and Airbus announced intentions to initiate flight testing using an Airbus A380-based platform starting in 2026.
In June 2023, General Electric completed initial tests of rotating components by integrating a high-speed, low-pressure turbine stage with a GE F110 military test engine. By late 2023, production of test components was underway to build a demonstrator engine for flight trials, combining an open fan assembly with a GE Passport gas generator core.
Technical Design
Contrasting with earlier contra-rotating configurations like the GE36 and PW-Allison 578-DX from the 1980s or Safran’s open rotor concepts from the 2010s, RISE utilizes a single-stage open rotor paired with stationary stator vanes. Both rotor and stator incorporate variable pitch mechanisms. The engine adopts a tractor configuration, positioning the rotor at the front rather than employing the conventional pusher layout. This single-rotating architecture was validated through the Clean Sky 2 initiative’s IRON project and is referred to by GE as the Unducted Single Fan (USF) engine.
The fixed stator vanes adjust their pitch to counteract swirling airflow and can nearly close entirely to serve as an air brake, thereby removing the necessity for a thrust reverser system. Furthermore, RISE integrates a recuperator that recycles exhaust heat to preheat air entering the compressor stage before combustion, enhancing overall thermal efficiency.
By 2025, this design will replace traditional turbofans and nacelles with a larger open fan assembly, targeting a 20% improvement in fuel efficiency. The engine is engineered to run on sustainable aviation fuels (SAF) at blends reaching up to 100%.
Applications
- Boeing X-66A (under development)