Will Open Rotor Engines be the next great leap in Decarbonisation?

The original development of open rotor engines, also known as 'propfans' and 'unducted fans', never truly gained traction due to several key disadvantages. These ranged from issues with excessive noise to business and economic constraints at the time. In a new era of environmental limitations and pandemics, could the targets aviation has set itself for the next decade prove the perfect breeding ground for the open rotor?

There have been significant advancements in gas turbine technology over the last decade in a bid to reduce engine fuel consumption, most notably the Pratt & Whitney Geared Turbo Fan, Trent XWB and CFM LEAP engines. Aircraft fleets data from IBA's InsightIQ currently shows 1,090 active aircraft globally powered by CFM LEAP family engines, all of which are Boeing, Airbus or COMAC types. The constant requirement to reduce emissions further has driven investment into developing more disruptive technologies within this aircraft class - enter the open rotor concept.

Concepts for application of the open rotor jet engine. Image: CFM

The open rotor engine aims to reduce fuel consumption by 20% and to reduce noise when compared against conventional gas turbine engines. The project tests key aspects in the design that included aero-acoustic optimisation, pitch control systems, contra-rotating reduction gearbox, lubrication and cooling systems as well as the rotating parts within the nacelle. Notably, noise issues were one of the key barriers to the success of the original open rotor development. The finished product would also be compatible with Sustainable Aviation Fuels, as well as potential Hydrogen fuel capability.

IBA believes the open rotor has the huge potential to disrupt and change the engine market - though it should be noted that with delivery not expected until the middle of the next decade, timelines may prove problematic for some OEMs.

The open rotor GE36 on a McDonnell Douglas MD-80 demonstrator at the 1988 Farnborough Air Show. Image: Andrew Thomas

IBA is an award-winning and leading independent aviation consultancy advising a broad mix of lessors, operators, financiers and investors. Operating globally, we inform decision-making and support operations across the aviation spectrum. Supporting strategic investments, managing aircraft, advising on expansion, or driving efficiency improvements, our mix of intelligence gathering, analysis, proprietary data, technical expertise and decades of aviation experience delivers value across aviation opportunities and challenges.

If you have any questions or would like to chat with one of our engines team about our services, please contact David Archer, Senior Engine Analyst.

IBA's InsightIQ analysis platform flexibly illustrates multiple asset, fleet and market positions, actual and potential, to inform client choices and identify acquisition opportunities. Immediate access to crucial aircraft, engine, lease rate and fleet data eases appreciation of historic and future aircraft concentrations and operator profiles.

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