This is a Plug Nozzle, a unique rocket engine made in 1960 by the General Electric Company. This engine is the first flight weight model produced by G.E. and developed 50,000 lbs of thrust. In conventional liquid fuel rocket engines, the combustion and expansion of gases take place in an inverted cone-like thrust chamber. In the plug nozzle, the propellants are ignited in a ring of small segmented chambers around the outside base of a large conical "plug."
As the gases exit at supersonic speeds, they are self-adjusting. This results in greatly increased efficiency of the engine in its low altitude ascent. However, NASA did not choose to adopt this radical approach to propulsion. The nozzle was donated to the Smithsonian in 1976 by the Wright-Malta Corp.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.