Hello again to the PPrune crew. This is Pete Gillies, away for a couple of days doing my day job.
As before, I extend special thanks to FH1100 Pilot for his great support in getting this simple message across to the many readers and contributors to this thread. And yes, Ray Prouty is at the top of my list of helicopter aerodynamics gurus. In fact it was at one of his lectures years ago that I picked up the first clue of what turned out to be my quest to make Cyclic Back an integral part of getting into a survivable autorotation.
I just reread my original post, the one that began this thread, and I see that I definitely made a mistake when I said that if the rotor rpm drops more than about 5% below low green or the lower red line (same thing), the flight is over. I should have said it may be over. In posts following that initial one I agreed that the absolutely critical rotor rpm may be well below that figure, but "low red" is determined after many, many flight tests that cover a particular make and model and just about every conceivable variation in D/A, airspeed, flight weight, center of gravity and things I haven't mentioned and probably have never heard of. The sales department wants the rotor rpm operating range to be from zero to infinity, but the engineering department seems to have difficulty reaching those limits.
So to those of you who have been bashing me about this "over" statement, please ease up a bit. I apologize for my initial choice of words. Let the un-powered rotor rpm drop below 5% below low red line and the flight MAY be over. Good luck to you if you want to explore that region without an engine to back you up.
It's been a long day for me here at our "left coast," but I promise to contribute again tomorrow. Guys, it's so simple: Here is is again: Power fails. Cyclic back and lever down, simultaneously or in that order. Pick a place to land. Make that spot.
Works every time but the cyclic back part is not needed from a hover.
We're already writing new software for power failures when on autopilot. And guess what? Cyclic back and lever down simultaneously! Duh. Lever down and then cyclic back? No way in hell...
This Cyclic Back thing is the Swiss Army knife of what to do when you are caught completely by surprise by a power failure while in forward flight. Can't remember anything else? Do this and you'll have a flyable helicopter all the way to the ground or water.
And for you non-mil pilots... Take a look at how many times and for how long your left hand is off of the lever during a typical flight. God gave us left legs so we could steady the lever conveniently while our left hand was, ah...well, you know...ah...hmm...have to be politically correct here...so YOU insert here (_______________) what sort of things you do with your left hand while flying SPIFR, for instance. As I said in a previous post, the lever (collective for all you Yanks) :-) is nothing more than a thrust control, a beta control. Set it and forget it for many types of missions. And it's a great place to rest your left hand, too.
Hey, I'll stop now and save something for tomorrow. My sincere thanks to all of you who support Cyclic Back in any way, shape or form. I'm buying the beer for all of you!
Pete