This is a partly graphite experimental liquid propellant rocket motor thrust chamber and nozzle developed in the 1960s or 70s by Reaction Motors, Inc. The graphite was chosen to help absorb the heat of combustion of the motor. It was used for short firing periods and for tests only. The motor was donated by Reaction Motors to the Smithsonian Institution in 1977.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.