HI ALL

Congratulations this week go to Logan Beck, who solo’d this past Sunday!

As a reminder, we’re currently open Friday, Saturday and Sunday. We are so happy to have seen so many of you over the past few weeks. We are very grateful to be back at work!

If you’d like to schedule an upcoming lesson or book a glider rental and you have a Schedule Pointe account, until further notice, please check availability on Schedule Pointe first (for Fri/Sat/Sun) and then e-mail us your reservation request. If you don’t have a Schedule Pointe account, please e-mail us date options for your reservation. Please include your cell number. Do not schedule reservations yourself, until further notice.
When we confirm with you, you’ll receive our new mitigation procedures. Be prepared to bring a mask, and your own water and sanitizer. We look forward to seeing you at the field!
Stay safe and healthy and wishing you good spirits,
The Soaring Academy Crew

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

 

HI ALL

We are back open on Friday’s as of 5/29!
If you’d like to schedule an upcoming lesson or book a glider rental and you have a Schedule Pointe account, for the present time and until further notice, you must check for availability on Schedule Pointe (for Fri/Sat/Sun only) and then e-mail us to schedule your reservation. Please include your cell number.Please do not schedule reservations yourself, until further notice.
When we confirm with you, you’ll receive our new mitigation procedures. Be prepared to bring a mask, and your own water and sanitizer. We look forward to seeing you at the field!
Congratulations this week go to Mitch Thomson, who earned his private pilot certification last Friday. Welcome to the addiction Mitch!
Stay safe and healthy and wishing you good spirits,
The Soaring Academy Crew

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!