How much the Concorde secondary nozzle contribute to thrust? Does anybody knows how much did secondary nozzles bucket type on the Concorde's engines contributed to the increase of thrust during take of and sub-sonic flight? This is picture of the nozzles  and here is air flow during take of  all images from this link https://www.heritageconcorde.com/variable-exhaust-nozzles  source states that secondary nozzles reduces noise, as well as improved engine performance. I suppose performance means thrust?
This source suggests at subsonic speeds, the secondary reduces drag but doesn't contribute significantly to thrust. 


  At all times below Mach 0.55 – on the ground, take-off and initial
  climb – the buckets are set to 21 deg., forming a ‘jet-pump’ gap at
  the nacelle trailing-edge. The high speed jet exiting from the primary
  nozzle draws-in atmosphere air from above and below the nacelle to
  eradicate a source of base drag that would otherwise exit between the
  nozzles.