Army helicopter school (II): Input-out...
by John DeWalt
U.S. Army helicopter flight school was an absolute blast―except for the first week or two.
I was fairly well coordinated and very highly motivated to learn to fly helicopters. But for the first couple of weeks, I began to think I’d wash out of flight school, that I’d never master the basic skills, that even though thousands of others managed to learn, I’d be one of the dolts who couldn’t fly a chopper...
We began flying right at the beginning of school―that is, it wasn’t all orientation and classroom work. Right from the start, we’d get an hour a day in the helicopter with an instructor pilot. Day after day, the drill was to learn how to hover the aircraft. Just raise the helicopter straight up three feet off the ground and hold it steady. Piece of cake, right?
There are three controls. The collective pitch control (“the collective”) is a lever on the left which slants up from the floor behind the pilot so the grip is by the pilot’s left knee and is operated with the left hand. Moving it up and down controls the helicopter’s vertical motion. The cyclic control (“the cyclic”) is a vertical stick between the pilot’s knees, operated with the right hand, which tilts the helicopter in any direction by tilting the top of the cyclic in any direction from the vertical. The pedals control the tail rotor―the little propellor at the back of the helicopter―which makes the tail of the helicopter swing to the right or left. The pedals are operated with the feet.
A helicopter pilot can, with his two hands and feet, raise the helicopter to a three-foot hover, swing the tail of the aircraft back and forth or rotate the aircraft in a 360-degree circle, and tilt the aircraft in any direction so that it begins to move in whichever direction it’s tilted.
Does it sound simple? Well, it is and it isn’t. The instructors certainly made it seem simple. But to the novice it seems impossible.
The procedure is to begin to pull up on the collective with the left hand until the helicopter is light on the skids, gently feeling the pedals and the cyclic to insure they’re centered and not pulling the aircraft one way or another. Then, as the aircraft breaks contact with the ground, the pilot gently maneuvers the pedals and cyclic to keep the aircraft stationary while continuing to pull up on the collective until the aircraft is three feet off the ground. It’s certainly simple in theory.
Why does it seem impossible to a beginner? For one thing, the wind affects the process. If there’s a breeze from the left, say, the pilot must tilt the aircraft to the left or else the wind will blow the aircraft to the right as soon as it leaves the ground. And if it’s not a breeze but gusts, the pilot has to keep moving the cyclic back and forth to counteract the gusts.
That’s a red herring. The wind isn’t the reason. Even with no wind, the beginner can’t hover the aircraft. A helicopter is light and unstable, and as soon as it’s off the ground, it will tilt and spin and move right and left with no wind at all. The real problem is that the beginner constantly overcontrols the aircraft. He waits too long then makes too gross a correction. It’s always too much too late.
For the first couple of weeks, I was pitiful, and so were all the other students. By the time I’d get the aircraft three feet off the ground, it would be ten feet away from where it was parked. It would be spinning and flopping back and forth. It really was pitiful, and pretty funny to an observer. We’d laugh out loud watching each other when we weren’t flying.
The poor instructors! It couldn’t have been funny to them. They must have felt death knocking at the door every moment. Oh yes, you can kill yourself from three feet of altitude. If you’re so erratic you let one of the rotor blades strike the ground, the other blade might slice through the cockpit, a plexiglass bubble, decapitating all souls.
One day, after about two weeks, I suddenly began to get the feel of it, and then made rapid progress. What a relief it was. Then I knew I’d make it, that I wouldn’t wash out of the program. This happened to all the students about the same time, except for the few who really couldn’t master the skill.
What accounts for the breakthrough? It was completely intuitive, just a feel for the aircraft which seemed to come suddenly then never left. It made me feel so happy and proud and worthy and accomplished! And I’m sure it made the instructors feel the greatest sense of relief―that for whole seconds at a time death wasn’t imminent and they might even relax a little—perhapts smoke a cigarette while the student was on the controls.
To tell the truth, I didn’t understand the “feel for the aircraft” that constituted the breakthrough to learning to fly choppers. I could not articulate the sense I had acquired.
Flight school was thirty years ago. It wasn’t until twenty-five years after flight school that I understood it. Five years ago a man came to my employer’s staff after serving ten years as a U.S. Navy helicopter pilot. He was a real pilot. He had ten thousand hours of helicopter flight time. He flew twin-engine, twin-rotor helicopters. He flew on and off ships. He made long flights over the ocean. He made cross-country flights. Most significant, he was an experienced instructor pilot.
It was a great pleasure to get to know him. He explained to me what I’d felt but never understood about flying helicopters. I call it the “input-out” principle.
Simply put, you’ve got to take out your input on the controls before you feel the aircraft respond to the input. You’ve got to trust that the aircraft will respond, that there’s just a hint of a delay in response. If you’re trying to maintain a perfectly stationary hover and the aircraft begins to move, you apply a touch of input to counteract the unwanted motion, remove the input immediately, and the aircraft will remain stationary. If you continue to apply the input until the aircraft actually responds, you’ve applied too much input and will then have to apply opposite input. This is what the beginner always does, and for the klutz, which is everyone at first, it’s downright dangerous with the aircraft flopping around every which way.
Obviously, this insight came twenty-five years too late. I wish my instructor had explained it the first day of flight school. I have enough conceit to think I might have been able to grasp the principle and begin to apply it the second day of school and eliminate those two weeks of agonizing fear and peril. I have to admit that my navy friend told me he used to explain this to his students the first day of school and no one could apply it immediately; but, who knows, I might have. At any rate, I no longer lie awake at night wrestling with something that puzzled me for twenty-five years.
This is the second installment of a three-part series on Army helicopter school. Continue to Part Three).