Developed by General Electric, the exhaust nozzle is designed to reduce the HSCT's noise during takeoff and landing without adversely affecting its performance. It incorporates the latest aerodynamic features that Boeing brings to the table and is representative of current HSCT designs. A pair of microphones mounted on traversing struts beside the platform and four microphones suspended from the wind tunnel's ceiling enable engineers to measure jet noise at different speeds, flap configurations and angles of attack. The nozzle has large air intakes which act like giant vacuum cleaners to suck in air. During the wind tunnel tests, cool air flows over the model and through the nozzle's air intakes, where it mixes with hot air from the jet simulator.
Low drag means less thrust, and less thrust means less noise.