. Helicopter Performance
Dr. Alexander Klemin (1925)
The aerodynamic tools described in the previous chapters can now be used to analyze the basic performance of the helicopter. By the term helicopter performance we mean the estimation of the installed engine power required for a given flight condition, determination of maximum level flight speed, evaluation of the ceiling (in and out of ground effect), or the estimation of the endurance or range of the helicopter. Both the momentum and blade element methods will allow for good estimates of total rotor thrust, power, and figure of merit in hover and can be used with confidence to predict overall rotor performance in forward flight. In addition, the performance of the helicopter during maneuvers, in descending autorotational flight, in flight in or near the vortex ring state, and during flight operations when operating near the ground will be considered in this chapter.