F-106B 57-2516, NASA ID No. N616NA of the NASA Lewis Research Center, Cleveland OH 1971 (NASA N816NA while at Langley Research Center, Hampton VA). Un-cooled plug nozzle with fixed outer shroud tested at military power only. A cooled version was also flown and tested with max afterburner on the test engine. An operational one would have a translating outer shroud for both modes. Transonic Speeds Research. [NASA via Earle Boyer collection]