A helicopter has a main rotor speed of 260 rpm, and a main rotor radius R=5.90m. The gross take-off weight is 30kN. The blades have an average drag coefficient of CD=0.01, and the rotor solidity =0.08. The distance between the axis of the main and tail rotor is x=7.5m. The helicopter is powered by two turboshaft engines with maximum continuous power at sea level of P0=1,150kW, each.
(a) Calculate the tail rotor thrust required to trim the helicopter in hover. [10]
(b) Assume that due to a failure in the flight control system there is an impulsive
excess of tail rotor thrust. What happens to the helicopter? Discuss whether the
worst-case scenario is during hover or level flight. [8]
(c) The altitude lapse rate for the engine power is a function approximated by
P(z)=P0 (/sl)1.35. Estimate the hover ceiling of this helicopter rotor, neglecting
the effects of profile and tail rotor power.
