Learning to fly Helicopters (4) ‘Auto-tribulations’
Posted on October 13, 2015
Learning to fly Helicopters
Ch. 4 “Auto-tribulations ”
(For Sam Mohring, because he said he’d like a sequel…)
It was several more months before I could get back to California.
This time I turned up with a very different attitude. Gone were the doubts. In their place was a lot more confidence. Confidence in the helicopter. Confidence in me. Oh, there were still doubts. And still, a certain amount of fear. I didn’t like autorotations. MY instructor told me I would end up loving them. Maybe. But I didn’t right then.
Looking back on it, I think my understanding of the aerodynamic principles of autorotation was not matched by my confidence in the blessed principle working. It sounds so simple. In powered flight, all normal, the engine powers the rotor system, via the transmission. Airflow is “induced” down through the rotor disc. Okay, happy-happy. Now, gremlins. What happens if the engine goes tiddley-up AWOL? As in Kaputt, seized, broke, busted, knackered? We simulate that in autorotation training. We lower the collective lever, that looks like a really old fashioned vintage hand brake, and roll the throttle off. Sadistic instructors enjoy doing this to petrified students. I’m sure they torture kittens as well.
Help! No ENGINE…??
What’s going to make the rotor blades keep going around?
Enter The Principle? The WHO? The Principle. That fancy Theory what asserts it’s all gonna be just fine and okay. You can imagine a swaggering type, all full of his self importance, puffed up in pride, because this is one helluva smart Principle, and he knows stuff you don’t. You mutthead…
“Easy”, says the Principle. “The Helicopter, faced with an engine failure, will initially drop. This is nothing to worry about.”
If you’re like I was, you might be inclined to reply:
“Nothing to worry about?? You must be… effin’ JOKING!”
The Principle, unfazed, continues: “Then, after you’ve dropped, guess what?”
“Go on, tell me.”
“Well, the upcoming airflow, now flowing UP through the rotor disc, instead of DOWN through it, will drive the rotors round. Simple. Works every time…” The Principle ends on a smug note. Every time. All full of himself. I’d like to kick him in the bolt securing devices. Wryly, I opine:
“Yeah. Simple. Huh. And what if it doesn’t? What if you don’t work, Mister fancy high-falooting Aerodynamic principle? Eh? Eh? What do I do THEN?”
I was… suspicious. To me, Rotor RPM was sacred. The Nr gauge (‘Rotor RPM Indicator’) was the key to life. With healthy Nr, you had a flying machine. A good, strong, healthy flying machine. (The Hueys in Vietnam were famous for chopping down TREES with their blades. Taking enemy fire in a small clearing, overloaded, nobody exactly wanting to get off, trees in the way… What do you do? Fly in circles, knock a few down, and… hey presto.) (Spinning Blades are tough) With collapsing Nr on the other hand, the centrifugal force was insufficient to keep the rotor blades flying out. They would “cone upwards”, desperately trying to fly, until in the end…
The vivid picture of a child, clapping its hands over its head, always came to my mind. A mental picture of the rotor blades “clapping hands”… followed by the equally disconcerting picture of the whole she-bang plummeting earthwards. Streamlined shrapnel… NOT good.
I didn’t like that idea. At all. I was still very much a high time fixed wing pilot. I was used to a nice, stable, fixed wing-PLANK hanging over my head. Or bolted on below my seat. You could SEE the wing-plank. It was always in the same place. It didn’t DO weird stuff. In the case of a biplane, there were TWO planks, with nice steel cables running between them and your fuselage. Life for a Plank Pilot seemed somehow simple. A whole lot less confusing. Now, once you start ROTATING those planks, well, all bets are off. Who on earth dreamed up that idea? Juan de la Cierva, for one. Holy Moly. Is this wise?
I had been converted to the strength and reliability of the Robinson helicopter. That long session with the super friendly mechanic described elsewhere had really helped. Provided you flew along normally, engine running, healthy Nr… all good. But this business of tricking around with the Nr/Rotor RPM… Auto-rotations? By WHY? Why not leave well enough alone? Why disturb it, just as things were going well? Hey, I can start the contraption up, take off, fly about, navigate. Come back in one piece, hover, land. Why have I got to practice autorotations? Lots and lots and lots of them? Why?
In case the engine quits? Or something else goes tiddley-upski??
It’s not going to quit. It’s a Lycoming O-320. Same engine as in my old Cessna 172. Goes forever. Never quits. Can’t I just do a private Pilot’s license on helicopters WITHOUT practicing autorotations?
Aw, shucks. I thought not. Oh, well then… And then we did a bunch. A whole gaggle of bunches. Millions of the little baskets. Straight in autos. Ninety degree turn autos. One-eighty autos. Three sixty autos. Short range. Long range. Fast. Slow. Inverted/upside down…!
Seriously! (No, I’m just kidding…)
It was always the same. Autorotation. We would enter the Twilight Zone. Auto-perturbation. My eyes would fly to the Nr gauge. It would do things. Oscillate. Depending on what you were doing. You had to control it. Keep it in a certain range. I felt like a high class hooker. In drag. A make-believe-this-is-actually-fun drag session. Trying to please Master. With a lever-whip that controlled DRAG. A drag lever. UP more drag, DOWN less drag. It’s all about DRAG.
Watch the Rotor RPM… watch it!…
If it went too high… not good… Need some MORE drag…lever UP… blades have a higher angle of attack, hence more resistance from airflow…. bring Nr back down. Ah… yes… It actually works…relief.
If it went too low… drooping… limp dick… bad-bad-bad… Need LESS drag. Lever DOWN. Now blades have a lower angle of attack… hence less resistance from airflow… Nr coming back up. Ah…yes… it actually works…
Too fast…? Needs more resistance. Dammit. Drag up. More drag!
Too slow…? Needs less resistance. Give us a hand here. Please! Drag down. Less drag!
The collective lever controlled the… the… Friction. It was all almost pleasurable, if you got it right. You just had to know how to juggle the lever.
Just like Katy down at the Bar X Saloon.
Enter Auto. Eyes fly to the Nr gauge. Mouth dry. Start breathing again when that settles down. Eyes fly outside. Where to land? Airspeed. Eyes out. Scan. Nr, airspeed, gauges… eyes OUT.
And I’m doing this voluntarily? For FUN??
Slowly, I got better. And better. But it was to be several hundred helicopter hours before I could truly, casually -almost- drop into autoperturbation, feeling relaxed -almost.
The breakthrough came eventually. Later on. Ironically, because I added a Helicopter Instructor’s ticket to my Fixed Wing Instructor ticket. Now I was free to TEACH it all. My way…
But in California I had not reached that happy stage. An auto was something to approach very warily indeed… Even after I had been officially declared quite proficient, they still would not come naturally. Some of my later students breezed through it all like it was a walk in the park. Others, worriers like me probably, had to be reassured, and could only be slowly exposed to Katy. Down at the Bar X. Imagination is a double edged sword. Always remember that child clapping her hands above her head.
There came a day for me, that I realized I still somehow dreaded Katy. And I was being prepped for my private Pilot check ride. You’d think I could swagger into the Bar X saloon, and hold my own. But no…
We were practicing landing and taking off on a tiny helipad perched way up on top of a steep mountain. The helipad was actually built on the ridge line. Quite fascinating. It got my attention, every time. Especially the way the ground would fall/plummet away below you as you lifted off… one moment you were in a four foot hover. You moved forward fifteen feet, and…
…below you a drop of several thousand feet would open up. Actually, the verb “open” doesn’t do justice to the phenomenon. It would be more of a techni-color visual EXPLOSION. A stomach lurching “Holy Cow” opening up. It has to be a brave man, (or a pilot devoid of imagination), whose stomach doesn’t lurch. The famous butterfly gang-bang. You may ACT all cool for the rest of the patrons of the Bar X saloon, but deep down a lot of us think to ourselves (very deep down)…
But, in my own way, I was quite enjoying myself. Around and around we went. Pinnacle approaches, pinnacle take-offs. Damn, I’m good. Pretty cool dude, me, leaning over on the bar, back in the saloon. Eventually, my instructor told his first ever student -me- to head on home. We were now several thousand feet up, the airfield in the distance, far down below.
“How do you reckon we’re gonna get down…?” The voice beside me asked.
I was puzzled. What kind of question was that?
“Why, just fly down, of course…?”
I looked at my instructor. He was wearing a look I had seen before. Many times. Officially, it’s the look of ‘quiet reproof’. Unofficially, it usually heralded in the unexpected. It was a look along the lines of “Have you learned nothing, thou inveterate fixed wing deluded plank thinker?”
An unseen hand firmly bottomed the collective, my stomach lurched, my eyes flew to the Nr gauge, and a loud -heartfelt- expletive burst from my lips.
We had entered auto-tribulation…
It certainly was a quick way to descend, and we were down within a fraction of the time it would have taken us to FLY down. It made sense. I realized that auto-perambulations had actually got PRACTICAL uses as well. Fancy that.
* * * * *
As I have said numerous times, I never understood the mindset of pilots who were careless with Nr in helicopters. Rotor RPM in a choppy is what airspeed is in a plank. It’s what keeps you alive.
But in the decades I have been flying helicopters, I have heard innumerable stories that convince me that this holy respect for Nr is -surprisingly- not universal. Afterwards, back in the UK, I heard stories about pilots who would fly along, and frighten their (knowledgeable) passengers witless. With their lackadaisical attitude.
One classic story bears repeating. This involved a character, who apparently would continue to look out the window when the ‘low rotor rpm warning horn’ would go off. This was in the days before Frank Robinson invented the throttle correlator. Which did stuff automatically the pilot had to do for himself in the old days. In doing so, he saved countless lives. Mostly of dudes who maybe just should not have been in helicopters in the first place. Back in the late eighties’, YOU had to match the throttle rpm to give you correct Rotor Speed. Just like a Bell 47. You had to pay attention. It’s not difficult, and it becomes pretty easy/routine after a while, but (like changing nappies) it HAS to be done. Well, genius character, successful business man, High I.Q., used to fly along and his ‘low rotor rpm warning horn’ would go off. It happened so often, that all he would do is -absently- lower a bit of collective lever to ‘get rid of that annoying sound’. When queried by concerned passengers, his attitude apparently was something like: “OH, THAT thing again… it’s always going off.” Needless to say, he eventually came to terminal grief. Yet another example of Brains-to-burn, brilliantly successful Business Man, taking a certain mindset with him into the cockpit. What is the root cause there? No imagination? A life time of bossing the world around, and bending those around him to his iron will? Listen up: It may work in business, it’s NOT going to work in the fluid world of helicopters…
My feelings then, and now, have not changed in this respect: The Robinson R-22 is a superb machine. Very well engineered by a man with an awesome design pedigree. But it is NOT a toy. It may look like a wind up toy. You may fantasize about sticking a four foot tall key into one side, to wind up the spring. You may on first sighting be inclined to wonder what might happen if you “add water”. Will it grow up into a real helicopter? But it IS a serious machine. Worthy of serious respect. A sensible fellow, gifted with a modicum of respect for the immutable Laws of Physics, can happily learn to fly a Robbo. His devoted wife, and their twenty kids, need never worry. Hubby will probably be a lot safer than driving his car down the motorway. Mixing it with all the crazies. He will be much safer scooting over the top of the whole lot of them. However. Don’t trick about. Treat the machine with respect. Treat the sky with respect. Listen to your instructors. Be AWARE of the pitfalls. Respect Nr. Simple. Happiness.
It was now time for me to build hours. In deference to my several thousand hours fixed wing experience, I was given a minimum of training, and turned loose. Go build yourself some hours! What, me? On your helicopter? I can go anywhere I like?
And so it came to pass that I turned up at an airfield that I had not previously been to.
Innocently, full of the best intentions, I proceeded on down to land. High time fixed wing pilot, fixed wing CFII, low time helicopter student pilot. Maybe not a good combination.
I was unaware that I was about to…
Make local Helicopter History…
Apparently, they still talk about it.
Yep, I’m a feature in Corona bar stories. (“you remember that Irishman…?”)
I describe the whole sorry saga… in the next chapter.
Last edited by Francis Meyrick on November 16, 2015, 4:52 pm