Lockheed Martin and Spike Aerospace are among the companies that submitted proposals to NASA in September to build a full-scale demonstrator of a supersonic passenger jet, Popular Mechanics reported Monday.
The bids come as NASA works to complete wind-tunnel tests on a 15-percent-scale model of the Quiet Supersonic Technology X-plane at Langley Research Center in Virginia.
Lockheed and NASA also conducted wind tunnel tests in February on a preliminary design model of the QueSST X-plane at the agency's Glenn Research Center in Ohio.
NASA expects to pick a contractor in 2018 and have an actual Low-Boom Flight Demonstration aircraft ready for initial flight by 2021.
The space agency's current X-plane model has a long nose with a flattened tip designed to reduce sonic boom noise.
NASA also plans to integrate other features into LBFD X-plane to ensure safety and reduce program costs such as the development of an external vision system with a camera in the cockpit, integration of a GE F414 turbofan engine and use of a T-38 aircraft's rear cockpit, the report added.