Last week, Boeing subsidiary Aurora Flight Sciences started work on phase three of a DARPA project to make a full-scale X-plane, the X-65, which could change aircraft design as we know it. 

Well, the X-65 isn't the only experimental aircraft under Boeing's wing. This week, the airplane maker started modifying an MD-90 aircraft, including removing the engines and taking 3D scans. The project is part of the X-66 design collaboration with NASA. 

After extensive modification, the MD-90 will become the X-66 Sustainable Flight Demonstrator (SFD). The X-66 is NASA's first experimental plane project focused on moving the U.S. towards net-zero aviation greenhouse gas emissions.