With full RPM on my rotor system, can I land my helicopter using only the throttle? That is, by just reducing power rather than reducing the blades' angle of attack?
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$\begingroup$ Do you mean a piston-engined helicopter with a twist throttle control? Also related in case it's a terminology confusion: What is “settling with power” and how does it differ from vortex ring state? $\endgroup$– user14897Feb 4, 2018 at 6:56
2 Answers
Assuming you mean a manual thrust lever with out a constant speed regulator: yes that is possible but not optimal. Best is to keep the rotor blades at optimum speed and reduce AoA of the blades by lowering collective - if you do that the thrust needs to be adjusted otherwise the rotor overspeeds, but it is still better this way than reducing thrust/rotor speed first.
If rotor speed is slowed down first, the blade speed reduces and with the collective at the same setting, the blade AoA will increase. So the safety margin with stall AoA decreases, at a time when it is required most.
Possible - yes. Recommendable - no.
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$\begingroup$ It should be noted that reducing rotor RPM is part of certain stuck-pedal or damaged tail rotor emergency landings. You should always be wary of turning your governor off, it may be illegal and very dangerous to do so! $\endgroup$– IzzyApr 13, 2018 at 16:02
Collective only landing is not possible, Because there is forward velocity, and the flight will get out of trim as soon as the throttle and collective are changed.