F-106B 57-2516, NASA ID No. N616NA of the NASA Lewis Research Center, Cleveland OH 1968 (it was NASA ID No. N816NA while at the Langley Research Center, Hampton VA) going through Underwing Supersonic Cruise Exhaust Nozzle tests during Transonic Speeds Research. The left wing engine nacelle was for Research while the right wing was for Reference. The left wing had a research Inlet and research exhaust nozzle, and the right wing reference nacelle had an open inlet and cylindrical nozzle. The 2 under wing engines were controlled from the aircraft's back seat, which the main F-106 engine was controlled front the front seat.