https://www.flightglobal.com/helicopters/sikorsky-boeing-unveil-defiant-x-for-us-armys-flraa-programme/142095.article
http://psk.blog.24heures.ch/archive/2021/01/26/sikorsky-boeing-ont-presente-un-sb-1-plus-aerodynamique%C2%A0-870464.html
Sikorsky-Boeing Team Unveils Defiant X
Sur le programme FLRAA: https://lf5422.wordpress.com/?s=FLRAA