Rotorhead

My friend Randy was showing me his remote control helicopters a couple months ago.  Actually he was flying a small one annoyingly close to my head in the confines of his basement recreation room, clearly looking to have a conversation about helicopters.  A larger scale model sat nearby, so I began looking it over, and soon Randy was by my side, showing me batteries and controllers, and in a rare moment of humility (PhD Chemistry, grew up in Paterson NJ, builds $10,000 guitars that are worth it) bemoaning his inability to even get the craft to hover reliably.
I innocently asked the first question that popped into my head.
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“How do helicopters fly sideways?”
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“The blades tilt.”
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It seemed that he must have been implying that the whole apparatus of the propeller tilted, which I had always imagined was the case, but at my urging he elaborated.
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“The blade changes its angle of attack on one side of the helicopter, really on both sides, every revolution.”
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I imagined a spinning helicopter rotor and tried to grasp how quickly this change of “tilt” of the blade had to happen (and unhappen). Thousands of times per minute, certainly. I made it clear to Randy that I didn’t think we were communicating properly, and he just said:
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“Yeah, that’s how it works.”
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Ah, Google, it is true.
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A device called a swashplate links the pilot’s controls to the rotorhead, the swashplate essentially being a disc affixed to a rod slightly out of perpendicular, so that rotation of the rod causes the edge of the disc to describe an oscillating path.
On a vertically mounted rod, the swashplate can act directly on connectors above it, pushing them up or pulling them down on one side of the disc as the rod is (slowly) rotated. These connecters, on a helicopter, push and pull at the hub end of each rotor blade, causing the blade to tilt (more or less), where more tilting provides more lift.
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To this point we have madly spinning blades, each manipulated so that it can provide MORE lift on one side of a single rotation and LESS lift on the other.
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My question, “How do helicopters fly sideways?” still felt quite unanswered, so I waded further in, finding that the rotor blade had other critical attachment points: The hinges: The “flapping” or”flying hinge” and the “lead-lag” or “hunting hinge”.
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The flying hinge is the most essential to understanding helicopter flight, as it allows the blade to “fly” or rise above the plane of a rotor spinning perpendicular to the rotor axis. I have just discovered that it is also known as the “coning” hinge, and this seems the most descriptive moniker of all. The degree the blade is allowed to fly is obviously limited, and hydraulic dampers are used soften the mechanics of the flailing blur.
The blades are thus flying higher on one side of the rotational disc and lower on the other, effectively “tilting” it and pushing the aircraft from side to side or fore and aft. This is called Cyclic control, and is managed with a joystick between the pilot’s legs.
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More “lift” (blade tilt) applied symetrically  over the rotating disc causes the craft to rise. This is managed through “collective control”, a separate lever usually found to the side of the pilot’s seat.
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The “hunting hinge”?
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The hunting hinge allows the blades to move toward and away from each other, as aerodynamic mayhem dictates, in the plane of the disc (think “hands of a clock”). Also limited and mercifully damped.
A separate, smaller rotor mounted on the helicopter’s tail, spinning in a vertical plane, pushes against the torque of the main rotor and keeps the body of the aircraft from spinning in the opposite direction of the main rotor. The speed of the tail rotor is controlled with yet another lever (or pedal) in the cockpit, and the craft is is directionally pointed by varying its rpm’s.
Finally, should you ponder riding in a “chopper” for reasons other than grievous injury or illness, consider the name of the hardware that sits at the very top of the main rotor’s stack of twirling, flapping, clattering mechanisms:
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The “Jesus Nut”

helicopter-a-1

2 responses to this post.

  1. A heroic attempt to explain a technical sequence which – unlike the writing of prose – doesn’t have the good grace to incorporate various artefacts and changing conditions in a straightforward linear way. A world of parallel events, in fact. I’ve been there and done that, notably in my last editorship of a logistics magazine. Logistics is all about response, reaction and a notable influence which plays hell with linearity – feedback. Meanwhile, you feel like saying, meanwhile…

    Considering you didn’t have recourse to diagrams you’ve done very well indeed. Me, I’d have taken the coward’s way out and asked the art department for assistance. I read and re-read the piece, noting the emphasis on clarity, the careful choice of words and – wherever possible – the insertion of words and/or phrases intended to lighten the load. Such as “as aerodynamic mayhem dictates”. Many people writing technical stuff are unaware that this is an option. I could also point to a rhythmic confidence which we’ve already discussed over at Tone Deaf; not achieved through varying sentence length (something that fiction allows) but through attention to sentence structure which would take too long for me to explain. Assuming I could. But I promise you it’s there

    And there is a lesson to be learned. You were in your pomp here, in control all the way and enjoying yourself. Why then were those qualities missing in your short story? And the answer isn’t rooted in different aims. The commonality is words and the way you handle them. There is no reason why you shouldn’t go back to that story and apply the same high level of competence you showed here. Better still, as an interim measure, write another short story based on helicopter componentry and how (I must be careful; I don’t want to be seen nudging your elbow) it mirrors some aspect of the pilot’s life. Too banal? You tell me.

    Reply

    • Thanks Rob, I appreciate this. I did pore over Google Image for diagrams, but couldn’t find one (or even an animation) that clearly demonstrated what I was describing. I believe I am understanding what you are telling me about the writing. It seems that a bit of dialog, a bit of humor, and some attention to opening up the text by way of spacing gives the reader a chance to breath and consider portions of the text more distinctly. Elementary stuff I know, but first things first. The “elliptical” aspect of stories, which you mentioned in comments, is something that I suspect will occur naturally at some point, perhaps by way of writing enough so that at some point a story leaps back or folds back on itself, becoming a bit of a circle. Your stories are valuable lessons as well as evocative reads, and along with the comments you exchange with your more entrenched readers they nudge my elbow on their own. Looking forward to more

      Reply

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