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Tuesday, April 7, 2015

Under the Big Top

By Frank Lombardi


I recently got together with a college buddy of mine to catch up on things. As he vented about his job, it was clear that there were many aspects of it that have caused him frustration over the years. “I swear, one day, I am going to run off and join the circus!” he said to me in desperation. I chuckled and reflected on my own employment, which definitely has its trying moments. I was about to agree with his idea of joining the circus, but then I paused. I realized I already perform in one.

Not to be cynical, but seriously, let’s talk about what we pilots wear. Have you ever glanced at yourself in the mirror while in full pilot garb? Total clown show. Well, that’s not where I was originally going with this; it just happens to be a related observation. Helicopter flying is difficult for many reasons. Unlike our airplane counterparts, almost none of our flying is kept in balance by the basic machine itself. While it can seem effortless to the unversed, in reality it takes quite a bit of work to tame the instability of the machine, especially in a hover.

The helicopter’s weak static stability (initial desire to return to trim), cross-coupling between axes, and creation of its own gusty air lend to its difficulty. It is also dynamically unstable in a hover. If we decided to stop the constant job of making tiny cyclic corrections while in a hover and freeze the stick, the first wind gust would begin the helicopter drifting. The increase in airspeed as it drifts would cause the rotor to flap back. The machine would pitch to follow the rotor, slow to a stop, reverse direction, then head back toward its initial trim with a gain in energy (i.e. speed). A pendulum action would begin, increasing in severity with every cycle. The good news is that the divergence happens slow enough that with practice we learn to cancel the oscillations out and hold our position with a great deal of precision… a feat worthy of any skilled circus performer.

Imagine if before every flight, someone announced, “Watch now, ladies and gentlemen, as our pilot goes up against a host of natural and mechanized forces that will try to topple him, including the most relentless: gravity. Prepare to witness him bring order to chaos, as he balances on a beach ball… that has been placed inside a bowl… while using fire to spin a couple of plates on the end of two sticks.”

Depending on the size and rotor characteristics of your particular aircraft, your beach ball may be very large, making it easier to balance. When things do get out of balance, the walls of the bowl work to return you to trim. If your bowl has steep walls, it will provide a stronger return towards the center-point but might make it easier to over-control; while a shallow bowl with less curvature will provide a weaker more gradual restoring force and may cause you to wander around on your ball. Whether you agree with my analogy or not, one thing is certain. You do not want your plates to stop spinning… at least not until the show is over.

I think part of the cynicism that many helicopter pilots develop is due to the lack of awareness that others have as to what it takes to do what we do. If only upon landing we were met with the applause and cheers from the crowd, as is the case when the circus gymnast takes a bow with outstretched arms. But alas, rarely does this happen. And really, we shouldn’t expect it to. Most of us do our job because we embrace its challenges, take pride in its necessity, and strive to perfect it to such a degree, that it just seems plain easy. It is for this reason, that instead of becoming frustrated with the uninitiated while we work to accomplish all this safely, we should be smiling and taking quiet pride in the difficult privilege of being a helicopter pilot. 

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