https://www.flightglobal.com/airbus-links-with-engine-makers-to-seek-clarity-from-authorities-on-open-rotor-airworthiness-requirements/86590.article
airbuslinksenginemakersseek
https://newatlas.com/ge-nasa-open-rotor-jet-engine-systems/11962/
GE Aviation and NASA will run a wind tunnel test program to evaluate and test counter-rotating fan-blade systems for open-rotor jet engine designs.
open rotorjet enginegenasagive