This attribute sets the ThrustEfficiency value to affect only acceleration calculations or to affect acceleration and mass flow calculations.
Astrogator <Satellite Object Path> SetValue <Attribute Path>.ThrustEfficiencyMode {Value}
Select from these values:
If the thrust efficiency is set to Affects Accel Only, then an efficiency of 0.98 means that only 98% of the fuel will be spent to get 98% thrust. For example, a thrust efficiency affecting acceleration only may represent some problem in the combustion chamber. An efficiency that also affects mass flow rate may represent an inefficiency in the propulsion tanks and feed lines.
Astrogator */Satellite/Satellite1 SetValue MainSequence.SegmentList.Maneuver.FiniteMnvr.ThrustEfficiencyMode Affects Accel and Mass Flow
STK Programming Interface 11.0.1