FORECAST ?

Last week we believed official forecasts, and offered a gloomy outlook that was disproven by the facts. The whole weekend yielded gorgeous thermal soaring, only enriched by a bonafide thunderstorm late one afternoon. This time the forecast is equally bleak, plus a bushel of westerly wind to keep it moving. So what else is there to say? Expect what Crystal almost always delivers, soaring that’s better than you’d expect, including possible wave on Sunday if it’s southerly enough…

OWLS ?

Last week we discussed (yaw) string theory in general terms, peeking into arcane questions like whether a string has more ends than one, and if so, which end is where we get the business. Elemental stuff for sure, but there’s more to keeping a string straight than knowing how it works.

Some pilots, even a few old salts, think yaw strings are unnecessary. That may be okay for them, but I say it ranks with keeping last week’s bugs on your canopy for the next flight — permissible, yet functionally dubious. Especially when anyone else wants to fly the plane. If those folk ever do clean their canopy, they’re apt to find the old tape peeling up at one corner because it’s been ignored so long, throwing in a ten degree error that makes their string useless anyway.

Crooked yaw strings can result from several kinds of aerodynamic flaw, such as an aileron (or two) out of rig, wings being of unequal weight, or not entirely symmetrical. Any glider with one wing replaced from a sister ship, for example, is a candidate for control harmony issues. And let’s not even mention angle of incidence! Problems like these may not make you call your shrink, but your mechanic might…

Yaw strings reveal other factors too, aside from the aerodynamic, that require us to become our own shrinks. How do I know? Ninety-nine point eight percent of my logged flight time over the current millennium has been in aft cockpits, studying from three feet behind how countless individuals fly. So yes I may be nuts, but I’ve seen enough to bid for a Dissociate Degree in Aerial Psychotomy, and can vouch that factors of the ‘human’ variety are usually what make yaw strings misbehave.

One very common error I’ve never heard anyone but myself discuss is flying supposedly straight, but not exactly level, and correcting for that with a toe’s weight of opposite rudder to stay on course. Its evil twin holds a smidge of rudder (routinely nosing into a crosswind) and one degree of involuntary bank as a fix. Same difference? Maybe, though maybe for different reasons… Either way it’s a slip. Imagine how much energy that wastes on a long flight! For the following discussion, let’s refer to any kind of inadvertent slipping in ‘straight and level’ flight as One Wing Low Syndrome, or OWLS. Got it?

Because all but the very youngest pilots drive cars, every one of us transitions from ground to sky with a heavy right foot, and/or a lazy left. Mental clubfoot from the getgo. To that, single-engine pilots add the same malady, brought from their habitual countering of P factor, which in gliders doesn’t exist. Given these and perhaps other reasons (could right- or left handedness also play a role?) it’s more often the port wing held low by most OWLS sufferers.

Launching in a crosswind also can skrew a pilot’s sense of level, well up into the tow or even throughout a flight. Seen it many times! After those initial seconds of holding windward wing low during takeoff, they seem determined to keep it there for the whole day. Even when called out on this, it’s amazing how soon many resume the error, completely unawares. Unchecked, it becomes a bad habit.

Others will hold one wing low for a while (or a whole flight), and then inexplicably switch sides for a comparable period, offsetting the whole time with that same reflexive toe of rudder to get where they’re going. They too will dutifully straighten up when reprimanded, but also relapse the moment something else crosses their mind. Almost funny to watch, but no.

This next example is not one infection site for OWLS, it’s an inbred family of them. No listing these in clerical order; each one’s effect is another’s cause, all overlapped and symbiotic. Let’s start with the subtlest and probe its roots, down to where some of the kin are much less benign.

Picture a broad panorama, nearly flat, with the horizon a few degrees higher on one side. That difference can lure an unthinking pilot into squaring with the mean horizon instead of true level, even miles from any hill. Reintroduce a pesky crosswind, less visually impressive at altitude but probably much stronger, and you have two deceptive inducements that can each lead to OWLS. Depending on wind direction, they might compound each other or partially cancel out, raising even more uncertainty.

Symptoms intensify exponentially as we come closer to high ground. Running ridge exposes a visceral urge to shy away from hills and/or lean into the wind, again necessitating opposite rudder to stabilize. Add a load of plain old fear, and soaring near high ground can seem overwhelming for a beginner. Problematic though all this be, ridge lift is nevertheless an ideal laboratory for identifying those bastards from the OWLS family and sorting them out, and there’s no better place to begin than the standard confusion between crabbing and slipping!

I catch myself committing these sins too, naturally, and the remedy is to always dedicate a certain portion of awareness and control, every moment of every glide, to enforcing wings really level and string really straight. An under-appreciated key here is the cultivation of quiet hands and itchy feet (truth I must no longer formally endorse, but can still whisper in an empty theater). While this veritable garbage bag of ‘human’ factors may reflect poorly on our intelligence as a species, the solutions are primarily up to us, and in this struggle the yaw string remains a formidable ally. Borrow a line from the ballers: string don’t lie!

 

Now before we spend this coin, let’s flip it. Say you’re one of the few with truly solid stick and rudder skills, and a finely tuned derriere to boot (pun intended). You know who you are — and you still have yaw string problems? Oh good. This is where you learn which of those mechanical issues we mentioned earlier apply to your bird, and look to resolve them. Yet another silent benefit from our humble little scrap of yarn!

YAW STRING FOLLIES

It’s been called the original heads-up display…

Oh you wanna talk retro? The yaw string was in fact history’s very first flight instrument. It performed so well with the Wright brothers’ glider, they installed one on their motorized version as well. A prototype designed with such brilliance, it’s still used all around the world in its original form! Well, except for maybe the tape.

Cool, so where do we plug it in? Answer: your brain. This humble little snippet of thread is absurdly efficient, but like any device, using it without your brain can be more trouble than it’s worth.

All flight instruments have a way of – pun alert – slipping between brain and mind, confusing what you see and what you think. A yaw string can do that too, if you let it. Pilots in glass cockpits don’t fix on any one of those cryptic symbols sliding around their screen, they maintain a suite of mental images, what each detail means individually, and as part of a whole. By comparison, we have it easy. Our little string is the square root of all that, one simple figure suggesting a range of reasoned responses from which to choose. Square roots are small yet potent, and bonus, your yaw string is still the only instrument that never lies!

Take but degree away, untune that string,
And Hark! what discord follows.

Shakespeare

Our problem is, humans instinctively read yaw strings backwards at first… Sounds dumb, but it’s nearly universal, and here’s a theory for why. We’re all used to reading meters of various kinds, with dials that rotate like hands of a clock. Nobody tells time by looking where the hands come together, right? From infancy, untrained eyes follow the lively part of anything that moves. Asking first timers to watch the lazy, unmoving end of a two-inch string is like telling a baby to not drool. Good luck.

So exactly how how does one use this string?

For those transitioning from power, we invoke, “step on the ball,” in our game, “step on the string.” But if that’s all we say, they’re guaranteed to step on the wrong end and get positively negative results. Next, they ask, “You mean if it’s pointing this way…” I’ve bitten holes in my tongue not screaming WHICH END? At that juncture, victims’ minds are disengaged from cerebral function, beyond the ordinary reality in which every string points two directions.

Another common bewilderment disputes which direction is forward, strange as that sounds. When first timers are settling in and want to adjust their rudder pedals, about half say “forward” to pull them closer, the other half say “back” to push them further away! This same cognitive reversal occurs with the string believe it or not. It’s why I always say, “Step where the string is taped to the canopy.” Fail to mention that tape, and invariably their mind tells them the only end is the one closest to their eyes, twitching in the wind.

My brain says look where the string’s going — and isn’t that the point? As it turns out, pedals are located ahead of the string, and the stick is aft of it. I follow the string’s far end with my (forward) feet, and follow its rear end with my (near) hand. Evidently that’s just too simple for some folks to comprehend. Millions have brains that apparently work some reciprocal way, with a vocabulary of mnemonic incantations forever beyond my grasp, but if it werx for them, that’s what counts.

Slogging through this conceptual fog one time, every verbal contortion left my student even more baffled, so I tried the last thing I could think of. I held our model with its tail pointed toward him so he could view it realistically, with the string off to one side indicating relative wind. “Realize that the string is ALWAYS straight,” I said, “Your job is to align yourself with it, one way or another.”

The student’s eyes brightened and he whispered, “Lightbulb!” Taking the model from me, he kept the string where it was, banking toward it and back, and then yawed into alignment by scooting his tail under it. Big grins all around.

Moderation is the silken string
running through the pearl chain of all virtues.

Joseph Hall, Bishop of Norwich

No doubt you’ve heard some wit advocate making the string cooperate by taping both ends — and maybe even repeated the quip yourself? Yeah me too, but here’s one that really did happen: a student was lamenting how the doggone thing just wouldn’t stay straight no matter what he did, as if there were something wrong with the string… So I said, “Maybe we taped the wrong end.” He was happy to agree, for a couple seconds. Then when his brain caught up with his mind, he blushed so loud the back of his neck lit up.

However folks visualize it, by the time they reach an understanding with their string, some are hypnotized and stop thinking about anything else. For others it’s so cheap and easy, and endures the worst neglect with such unobtrusive aplomb, they forget to even look, passively renouncing the string’s inexhaustible service. The only thing worse than being enslaved by your yaw string is ignoring it. Smart money splits the middle, like the oracular string itself. Look through it to where you’re headed and integrate the data subliminally. No need to focus on the string itself, go do your thing.  Just keep ordinary reality in mind as you do.

Also, no rule says your response must be only pedal or only stick. Generally, you’re either coordinating a turn or straightening out a glide, depending on the situation, and often the best input is a wee touch of both…

If it were any simpler I probably couldn’t fathom it either.

HI ALL,

May as well get ready for a cloudy week this time. After poring over the forecasts to fabricate an optimistic interpretation, here’s the best we could do. Friday’s overcast and probable rainy periods will mark the start of a ‘warming’ trend that may peak at 75 degrees on Monday afternoon. Winds will be moderate throughout, with possible thunderstorms (gray thermals?) on Saturday, and some improvement on Sunday. Oh well, a month from now we’ll be fondly recalling these last cool days of spring…

SEE YOU SOON!