One of the main challenges for future aviation is reduce fuel consumption and CO2 emission by aircraft.  Manufacturers focus, amongst others on new propulsion technology.  The Contra Rotating Open Rotor (CROR) is one example. The open rotor combines the best characteristics of a conventional turbofan and a turboprop. Thanks to the crescent shaped rotor blades, cruising speeds can be attained equal to those of a passenger jet. The diameter of the rotor is no longer restricted by the dimensions of the engine nacelle, and the introduction of a second rotor can reduce swirl, which is the loss of power inherent to propeller-based propulsion. Fuel consumption and thus CO2 emission are markedly lower than those of an aircraft propelled by conventional turbofans.

New computer models can map out and forecast the characteristics of CROR, such as rotor vibration, noise emission and forces on specific components. This knowledge may be essential in identifying adjustments to the CROR concept, so that it complies with current and prospective noise limits. Innovative solutions in this area were investigated in the past year.

The accrual of knowledge on CROR enables the air transport industry to make reliable decisions on the application of new propulsion technologies in a new generation of medium-haul aircraft, of which airlines currently have thousands in service.