This is for R.C. helis, but I would guess?? it might apply to full scale as well.
Using the Darkhorse calculator :
Dark Horse - Helicopter Power & Setup Advanced Calculator
or Motocalc or webocalc http://flbeagle.rchomepage.com/soft...c_imperial.html
or other R.C. power/thrust calculators yields similar results for static thrust, for a heli.
Is there a ballpark estimate / formula to convert excess thrust to climb rate for a heli, assuming a straight up vertical climb ?