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Recently the thought of autogyro flight as "powered autorotation" came to mind. The rotor acts like a fixed wing, providing lift, while a separate source of thrust provides forward motion.

A helicopter tilts its rotor forward a bit using for both lift and thrust.

But once it moves forward, it would seem the change in relative wind through the rotor may improve its lifting efficiency. But, as with fixed wing aircraft, forward motion increases form drag.

What does a helicopter pilot do with the controls when the helicopter accelerates to cruise? How does the rate of fuel consumption change?

Robert DiGiovanni
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    The power required diminishes from hover till a speed known as $V_y$ and then rises again till $V_{ne}$, a bit like an airplane. – sophit Dec 26 '22 at 15:24
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    That diminishing of power till $V_y$ is because in hover, the helicopter flies it its own downwash, whereas in forward flight, this phenomenon is largely reduced. This downwash in hover causes induced drag on rotor blades, and requires more power from engine for the same amount of upward thrust. Beyond $V_y$, the parasite drag takes over ("ahead of the power curve") and so the power required increases. Also, at higher speeds, the functionality of the tail rotor is virtually replaced by the more efficient vertical stabilizer, which further improves the efficiency. – Aditya Sharma Dec 26 '22 at 23:50
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    @AdityaSharma you might want to make a proper answer out of that, probably with some diagrams & graphs, ideally with measured values from the real world :) – Apfelsaft Dec 27 '22 at 03:37
  • You cruise an R-22 at about 90-95% of max power, Max Continuous, so if you are very light and say only 80-90% is required to hover in ground effect, the fuel burn in max cruise would actually be higher if you want to cruise at max cruise speed. – John K Dec 27 '22 at 04:44
  • Does this answer your question? – Koyovis Dec 27 '22 at 09:50

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