Originally Posted by Graviman
Gyromike,
Is there any advantage in autogyro of a 3-blade articulated or even rigid head rotor? This would get around many of the reduced-g control loss problems, and elastomeric bushes are widely available (ie cheap lead/lag hinges possible). I remember being told about an ex-Westlands guy doing some work at Bristol uni - but it may have only ever remained theory...
I'm also puzzled why a teetering gyro seems easier to fly than say an R22. Is this just due to the direct control system, or does less rotor mass help? I'm a fan of the '60s Lockheed gyro system, but am now wondering if there is some inherent advantage to being in permanent autorotation...
Mart
Sure Mart.
A multi-bladed head would provide 'head moment' to be able to maintain attitude during low G events. There have been a few one-offs built over the years, also the McCulloch J2 and Air & Space 18A gyros.
The 2-bladed teetering systems are just simpler and less costly.
But it's not the rotors that are causing the problems. It's the unstable framework underneath.
Eliminate the thrustline offset, and use generous tail surfaces, and even 0 G events are a non-issue (provided you aren't flying into tornados and such).
If you use a a full-span vertical stabilizer in addition to the horizontal to help eliminate torque roll and slipstream yaw with power changes, you can reduce the dangers caused by unloading the rotors. During a momentary unloading of the rotors, the aircraft will continue to track into the relative wind while the rotors reload. The problems occur when you are using rotor thrust to counteract rolling and pitching forces caused by the unstable airframe.
The Dominator that I linked to above actually has a slightly low thrustline which will tend to raise the nose in a low G event, helping to reload the rotors.