X-66A. To be built in partnership with Boeing, the X-66A will serve as NASA's Sustainable Flight Demonstrator. The goal is to showcase a new aircraft configuration that will help the aviation community achieve net zero greenhouse gas emissions by 2050.

Yes, NASA is actively involved in "making" several experimental aircraft, though they do not manufacture commercial planes for public sale. The most prominent current project is the X-59 QueSST (Quiet SuperSonic Technology), which NASA is developing in collaboration with Lockheed Martin. The goal of the X-59 is to fly faster than the speed of sound without creating a loud, window-shaking sonic boom, potentially paving the way for the return of commercial supersonic flight over land. NASA is also working on the X-66, an experimental "Sustainable Flight Demonstrator" built with Boeing, which features a "Transonic Truss-Braced Wing" design. This aircraft is intended to be much more fuel-efficient than current narrow-body jets, helping the aviation industry reach net-zero carbon emissions by 2050. These "X-planes" are strictly research vehicles used to test new technologies that NASA then shares with private companies like Boeing and Airbus to improve the future of global air travel.