Zero G and Prerotator

[rtfm]

Hi there,
Another (possibly) silly question: speaking as an amateur, non-technical person, it seems that one of the major drawbacks of any Gyro is the fact that they cannot sustain zero G while in flight. If this is the case, why would it not be possible to engage the pre-rotator should this happen? Or taking it a step further, why not have the pre-rotator permanently engaged?

Just a question...

Duncan

[birdy]

Speaking as a simple cow grower,I'd thought of that too.[befor I started flying.]Now that I done a few hours ,I'v never been in a 0g situation long enough to need to.[I'v tightened the shoulder straps only 3 times in 2000 hours,and they were only quick jerks on the straps,not sustained -gs]
If they were real -gs,I wouldn't be typing this post.

If you experianced any sustained -g force,the prerotator wouldn't help because you would be dead before you could enguage it.If you did actualy get time to engauge,the only thing that would happen is the machine would start to rotate opposite to the rotors,and the effect on the rotor rpm wouldn't be sufficiant to hault a PPO.

I maybe a simple cow grower but I'm not going to go and pull -gs and test me theroies.

[Harry_S.]

Birdy is right. If RRPM decays sufficiently, say due to unloading from any cause, it will start to flap and dramatically increase to destruction; if your airborne, you've had it. Never--Never intentionally approach 0 g. If airborne and your caught in a tenuous, light in the seat situation, remove power and bring the stick back to recover positive g., when RRPM stabilizes, add power.

All gyro models have different RRPM ranges. RAF has a safe min. RRPM of 270, which means maintain RRPM above 270 for safe flight.

[KevinKing]

Dick Degraw's GyRhino and DeBird gyros both have power going to the rotors full time. I don't think this has anything to do with preventing rotor decay in 0 G situations, but it allows the rotors to fly at a lower AOA, so there is less drag.

[Harry_S.]

That's absolutely true but, we had reference to un-powered rotors.