Low-G Pushover and Rotor RPM Decay
A private pilot is cruising a gyroplane at 1,000 ft AGL and 70 mph with rotor RPM steady at 340. Crossing a ridge, the aircraft encounters a sinking air mass and loses about 300 ft. The pilot pushes the cyclic firmly forward to stop the descent and keep the nose level. Immediately the stick feels light, the nose drops further, and rotor RPM decays to about 280. Airspeed decays toward 55 mph even though the nose is low, and the vertical-speed indicator shows 1,200 ft/min down. The engine is running normally at cruise power, and the pilot is 6 miles from the nearest airport with 1,500 ft of clear field below. The pilot's instinct is to push over more and add power to recover the altitude quickly.
1. Explain what happened aerodynamically and why the stick feels light.
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Pushing the cyclic forward reduced the rotor disc's angle of attack and unloaded it. A gyroplane rotor is driven by air flowing up through the disc; when the disc is unloaded, the driving region shrinks, lift falls, and rotor RPM decays. The light stick is the warning: rotor thrust is low and the disc is no longer supporting the aircraft.
The nose-low attitude, decaying airspeed, and 1,200-ft/min descent show the aircraft is trading altitude for speed rather than recovering. This is not a fixed-wing stall-it is a low-G, low-rotor-energy condition. If RPM continues down, the rotor can become uncontrollable and the descent may not be arrested. The correct response is not more forward cyclic.
2. What is the correct recovery sequence, and what cues confirm recovery?
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Stop pushing immediately. Apply smooth aft cyclic to reload the rotor and restore positive G. Accept the altitude loss-do not chase altitude. Hold airspeed at or above the best-glide/best-rotor-RPM speed, keep the bank shallow, and add power smoothly once the rotor is loaded. Avoid abrupt pitch or power changes.
Recovery cues are increasing rotor RPM, a firmer stick, and a decreasing vertical speed. Only after RPM is stable should the pilot consider a turn. Given 1,000 ft AGL and a clear field below, the field is a better option than a 6-nm turn back to the airport. If RPM cannot be restored by about 250 ft AGL, prepare for a hard landing and protect the cabin.
3. Why is the pilot's instinct to push over more and add power dangerous?
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More forward cyclic would further unload the rotor and accelerate RPM decay, possibly past recovery. Adding full power while the nose is low increases speed and can worsen the divergence. Altitude is the only energy available; the pilot must trade it for rotor RPM, not for distance or a quick altitude recapture.
A turn back to the airport at 6 nm would require altitude and would likely put the aircraft downwind. The clear field below is the safer choice. The key lesson is that in a gyroplane, unloading the rotor is the emergency-not the sink itself. Smooth aft cyclic and patience are the recovery.