THE DEVIL YOU KNOW

Everybody’s familiar with generic dust devils, especially here in the desert, though it seems few really know much about them. To most they’re just a fleeting visual oddity or at worst an enlightening nuisance, until you’re three seconds from touchdown in a glider. After landing through more jacks-in-the-box than I remember at this point, my commonplace familiarity has weathered to a crusty alloy of eager fascination and wary dread.

Our atmosphere is populated with spinning phenomena of all kinds and sizes, from those that toss houses around to the minuscule jets erupting from a stick of firewood. All share the same helical structure, despite extreme contrast in their origins, media, and cargo.

First, let’s exclude hurricanes and tornadoes as classes by themselves, in terms of size, power, and physical genesis. Even we don’t need that much energy for a good time! And may as well dismiss the entire range of ordinary rotor phenomena too, if for no other reason than their axis is principally horizontal, not vertical, and our aim is to climb away from that axis rather than along it.

Scaling down from there, whirlwinds of one kind or an other occur naturally in nearly every physical environment, many benign, some horrifying. Wing vortices, smoke rings, the wakes of falling maple seeds… Anyone who’s ever hitchhiked knows about those gritty swirls that kick up on roadsides after a freight truck roars by. They’re all about wind too (albeit highly localized), even on a calm day! And then we have a gazillion unique moments that can only speak for themselves, like the magical one linked here:

https://www.youtube.com/watch?v=JVCdBMlC5og

What’s called fire tornadoes are hellish gyres that erupt from within already raging flame. Enough to make you wish for the seeming opposite, a waterspout! Other variants consist of driven snow, sometimes called spindrift. The video linked here illustrates a wobbly mix of icy wind, thermal convection, and even rotor:

https://www.youtube.com/watch?v=V_xD8JZqtkc

Now about our impetuous friends, the devils: objects of any kind flying in a circle (except helicopters and drones) betray certain rising air. Visible dust and litter usually falls away by a couple thousand feet up, but I’ve circled with a chunk of sod at 3000 AGL and flown through pepper storms of sand lofting into cloud base more than two miles above a lakebed!

Devils normally spin counterclockwise in the northern hemisphere due to the weak yet ever present Coriolis effect, but topography and localized wind can exert greater influence in either direction. Notice how eddies at the shore of a river tend to swirl away from the main current toward land? That’s due to drag of course, and the same thing happens in air. High ground pulls it into whorls that spiral off from stronger flow, like behind a freight truck only different. (The reason we care is, turning against any rotation allows smaller circles in stronger lift with flatter bank, and therefore slower airspeed for a faster climb.) Then as rotation slows and widens with height, its direction gradually ceases to matter. Final authority: if there are birds nearby, always presume unerring instinct and follow their lead.

In desert country where devils are most common, they typically match the color of ground below and may be nearly invisible from high overhead. But bright sun can help you spot the shadows of dust columns, faint gray ovals moving downwind. Those are more discernible when the sun is high (the very time that devils are most numerous), as light is then falling further through the column, concentrating and darkening its subtle shadow. Also, diffused light coming the other way will make minute terrain features appear blurry. Watch closely any small area that seems less sharply visible, to find if that blurriness migrates across the surface. Blurry spots creeping along beside faint shadows are the blue sky equivalent of a sure thing!

Dust devils can provide crucial detail about surrounding surface conditions as well. Two devils less than a mile apart imply a line of lift between them, and three in a row nearly confirm it. That line might drift sideways at approximately a walking pace, while devils tend to slide along it in a geometric sum of two separate air masses’ movements. Or a line may hold relatively static as the devils follow it, straight downwind. Maybe both, depending where you look. Over open country under a cloudless sky, such information might be all you have – and all you need – to inform your next decision…

Finally, a couple more links to devilish video. The first is a classic biggie in the Valley of the Sun (Phoenix), and excellent as the photographer’s effort was, it’s good we were on different roads while she was filming:

https://www.youtube.com/watch?v=-RoylldGwpc&t=22s

This last link is to Burning Man in the Black Rock Desert of Nevada, one moving picture worth several thousand words!

https://www.youtube.com/watch?v=nSJkydvQTJY&t=155s

 

I’M PROBABLY WRONG ABOUT THIS…

I’ve always believed thermaling slower than minimum sink can be worth a small penalty if it helps you stay in better lift more of the time. Same for banking 60+ in strong narrow cores. Not that either is always the best idea, but sometimes they feel too good to resist, and in fact I have outclimbed a lot of pals that way.

General soaring wisdom says thermal no slower than the min sink for your angle of bank plus a knot or two for better control; and more than 45 degrees is too steep to do much good. Fair enough, but that’s General wisdom (like Einstein’s General theory compared to his Special one, only lightyears dumber). Soaring wisdom of the Special variety says do whatever works and pay the fine only if you’re caught. Longstanding rules of thumb are worth their weight in piñatas, but like distance, speed, and even altitude records, they’re ultimately meant to be broken. The world is filled with fascinating examples.

If you spend enough time watching ravens in thermals (which I obviously haven’t, ‘cause I still do it every chance I get) occasionally you’ll see one circling as usual, except with both feet hanging down. It looks kinda goofy, but if we’re honest, so does nearly everything we don’t understand.
Ravens may fly like that for no reason other than they want to, the way kids jump in puddles walking home from school. But don’t be fooled, the goofiness those two species share is a symptom of formidable intelligence seeking an outlet. When we see ravens (or kids) daily committing half of the seven deadly sins, that’s genetic programming at play. Genius in the making. Keep an eye!

Might a raven’s flying with gear intentionally down be something more than birdbrained folly? If a car’s antenna adds measurable drag to a ton of steel, those dangling legs and long claws must add more to a two-pound bird by orders of magnitude. I say there has to be some material benefit.

Any ideas?

Here’s one. Where is it written that drag is always a bad thing? That’s like not wanting brakes on your bike ‘cause they’ll only slow you down. Remember, drag pulls you back – horizontally that is – but not down down.

If you could reduce speed without raising angle of attack or interrupting uniform flow over the entire wing, it would allow tighter turns to hug stronger lift in the thermal’s core. Of course slightly slower airspeed will also produce slightly less aerodynamic lift, but what if there’s a wee numerical sweet spot between these concepts, akin to the one between min sink and best L/D? If only we had a way to cause a hair more drag without decreasing aerodynamic lift…

So here we go. I’m probably wrong about this, but it’s a puddle I’ve always longed to jump in. Why not try lowering your wheel in a thermal once, only for the climb, just to see if maybe those ravens know what they’re doing? If it turns out to be a mistake it won’t cost much, and who knows, you might even learn something. After all, birds have been doing this a million times longer than we have!

TALE OF TWO IRVS

Two of the most memorable characters I’ve met in soaring grew up in the Great Depression and by coincidence happened to bear the same first name. Though neither had much formal education, both became pioneering designers. One is ensconced in the Hall of Fame at the National Soaring Museum and the other should be.
Irv Prue was a technician at Lockheed in the fledgling aerospace industry after WW II, and by all accounts was a helluva soaring pilot. He built his first glider with a surplus drop tank as a fuselage, attaching homemade metal wings and a V tail. Working alone in his Pearblossom, CA shop, he was renowned among soaring home-builders as the prince of sheet metal fabrication. His Prue Standard was for a short time the standard in the rapid evolution of racing sailplanes, and his enormous Prue II became the highest performance two-seater of its time. It was lost to a wind storm, but a second version with slightly shorter wings and a T tail now rests in the Soaring Museum, having flown a world distance record out-and-return flight from Crystalaire in the 1970s.
Irv Culver was an intuitive genius who never went to college – except to lecture on graduate physics. While working for Kelly Johnson at Lockheed’s covert research and design office Irv answered the phone one hectic day with a sardonic, “Skunkworks,” referring to a fictional distillery in the old Li’l Abner comic strip. According to legend Johnson fired him for that indiscretion, something he’d often done before… and of course Irv was back at work the next morning.
The epithet stuck. That outfit, source of such advanced craft as the U-2 and the SR-71 has long since become a household name, and cute little Pepe Le Pew is now the widely displayed mascot of Lockheed Martin Corp.
Culver’s first glider was the all wood Screaming Weiner, its thirty-eight foot wingspan configured to fit in his garage. Auto-towed from dry lake beds with 5,000 feet of surplus wire (in those days hemp rope was too expensive), he flew the Weiner high and very far across the Mojave in an era when most glider pilots could stay aloft for only a few minutes.
Irvs Prue and Culver rose from different backgrounds but their suns set in remarkably similar fashion. Prue’s final project was a ‘primary’ glider like those of the very first generation, in which the pilot sits out front, completely exposed. All metal and held together by 150 rivets, it was designed not to soar, but to be built, deconstructed and then built again year after year in high-school shop classes. For that aircraft’s only flight, aficionados of several persuasions lined both sides of the runway to capture the moment as Prue, well into his eighties, was towed aloft behind a car. My indelible memory is his whishing by just after liftoff, his feet at my eye level in huge black shoes, newly polished. The flight was very short, but went well of course. A faint little dip of the wing in each direction, one just before release and one just after, to a cotton soft landing. And it would be his last.
That very evening, Irv Culver was convalescing in a residence at the same airport. His final project had been consulting on the superlight foot-launched Carbon Dragon, opposite end of the spectrum from those mega-powered near-space exotics he helped create generations earlier, yet still pushing the limits of innovation. As Culver glided into dementia’s twilight he’d be staring blankly at his coffee cup when some key word in ambient conversation would arouse his once-dazzling mind, causing him to brighten and grumble, “Wrote a paper about that.” When asked to elaborate, he’d lose me completely. Was he over my head, or departed from his own? No matter, his work was done.
One rainy Sunday, Prue sat telling stories of his heyday, flowing from one saga to the next as I listened spellbound. After two fascinating hours he stood, looked at his watch and said, “Well, thanks for listening.” I begged him to stay, but his therapy was complete and he ambled off. Never saw him again.
To have stood in the shadows of these giants is a priceless blessing and an everlasting privilege. It’s said that in their prime our two Irvs were rivals who thought poorly of each other – perhaps because they were so alike. But time alters everything. I had the honor of knowing them both near the end of their lives, and one of the most touching tableaux I’ve ever witnessed was these two fading patriarchs across a table from each other, heads down, whispering and scribbling on a napkin. Teamed up at last, and driven still to concoct new marvels, even as their shared hourglass ran out.
Both Irvs passed on only months apart, and to sadly little acclaim. Their lives had been long, supremely noble flights of unprecedented fancy, but their ends, like all good landings, were anticlimactic. Such is the way.

STIR CRAZY?

Seems cabin fever is now the new indemic, and everybody’s catching it all at once. Flyers under lockdown can be like caged birds, with brains way too big for the chore. It’s only natural to daydream about wonderful flights, past or future, and all the adventures we have or have not yet enjoyed. Fantasy is a fundamental human element, essential to mental health. But after all of that’s exhausted and you’re still stuck inside, how ‘bout the other extreme, flights made memorable by excruciating tedium? Got to be a story there somewhere.

Beginners might suppose it impossible to get bored aloft. I thought so myself for a few years, until entropy overtook me. I’d already logged several hundred hours of CFI before ever experiencing the faintest hint of dispassion for soaring. It happened where you’d least expect, my first checkout at a gliderport in the Southwest, eagerly expecting to have my mind blown. Prior to that, everywhere I’d been the challenge of simply staying aloft preempted any shade of indifference, but this was just too easy.

A booming thermal came as no surprise. I’d seen ten-knotters before, though never to 9000 AGL! With no clouds anywhere and the nearest hills miles away in two directions, I thought, ‘Now I’ll start to learn this new language of the desert.’ I asked the instructor where to head next, and he was audibly yawning as he said, “Ah just go straight, you’ll hit lift.”

He was right. What we tripped into seconds later felt the same as what we’d left. No strategy, no tactics, nothing but gobs of tall blue thermals standing shoulder to shoulder. So now I knew that aerial ennui was also a thing.

 

My personal benchmark for stir craziness was a typical late summer day in hazy old New England. I’d been mowing grass since morning, persuaded there wasn’t much up there to miss. All flights had been short ones, reporting not quite enough of anything anywhere, liftwise. The day was well past peak by then and business slow, so I took my usual 1800-foot tow to trusty old Elmore in search of a cure for gravity.

Turned out those discouraging debriefs were accurate, no lift of any kind — except a certain small declivity in the slope collecting a smidge more than its share of both sun and wind. In the 2-33’s smallest possible figure-eight, I was able to hang at one altitude for (abashed to admit) one of my longest flights that season. Three whole hours, actually.

Cabin fever began halfway through the first hour, anticipating a slide for home after the very next turn, or maybe the next… turn after turn after slow return. As the fever raged through its second hour, I sang versions of Eighty Hundred and Eighty Eight Bubbles of Eights on the Wall, but that got old too. Mused for a while about going full zen and flying all night (as it happened, there was a full moon scheduled). Had to grin at the notion of search-and-rescue folks tramping diligently through the woods until my shadow crept over them at two in the morning… No, that wouldn’t do, they might get mad and shoot me down.

On and on it went, delirium eventually settling to sheer drudgery, through what seemed a thousand nearly identical figure-eights, and honestly never gained or lost more than fifty feet. Grew more than a little drowsy at the helm before sunset mercifully stilled the breeze and brought an end to that voluntary ordeal, but I did stay up! And that’s the whole story. Two mile tow, three mile final glide, and a ton of zeros in between.

So yes, even soaring can become boring. But when circumstances make it so, remind yourself that a case of numb butt is more enjoyable in the air than on the ground.

And similarly, a case of numb butt on the ground is less permanent than one in it.

Happy hiding!