What would you say, in percentage, was the power the tail rotor steals from the main unit when used to full right pedal?
I'll make a leap of faith and take it that you really mean "when the tail rotor is producing maximum thrust to counteract main rotor torque" since the answer would otherwise depend on whether you're talking about a Eurocopter, which spins the main rotor in a direction that God never intended, or say, a Bell or Sikorsky that turn the main rotor in the
proper manner.
But with that nit picked, I offer this quote: "
Tail rotors typically consume up to 5-10% of the total power" ... click here for source document
This is from a helicopter aerodynamics course taught by Prof. J. Gordon Leishman at the University of Maryland.
The complete document is an interesting although fairly brief discussion of "conventional", tandem, and co-axial rotor configurations.
