February 18th, 2021
Soaring with the Raptors
by Dennis Linnekin
Maybe you've heard the ominous saying, "The Vultures are circling." When I was a kid, it was well-known (to me anyway) that "vultures circle over dead animals." When I became a glider pilot, I learned what those vultures were really doing in the summer sky. It turns out that the soaring vultures I was observing were climbing. And, most notably, they were climbing without flapping their wings! Vultures and all soaring birds accomplish this by sensing updrafts and then circling to remain within the rising bubble or shaft of air. Such shafts of helpfulness are called "thermals" because they are triggered when the sun heats the earth's surface, and the ground then heats the air above it. Warm air rises, and so does the vulture, with little expenditure of energy. Watch a vulture or hawk the next time you see one circling, and you'll notice him become smaller and smaller as he climbs. Soaring birds can do this with no effort other than sensing the rising air and maintaining a circle within it. This is what glider pilots learn to do in their aircraft. We know to find and exploit the rising thermal "lift" provided by the sun's energy. Once learned and practiced, a glider pilot can link a thermal climb with a glide to the next thermal lift. So, we climb and then use the altitude gained to glide for miles until we must find another thermal and rise again. Many clues show us the location of the invisible thermals that we must locate. These include features on the ground such as hills, lakes, dust devils, forests, and features in the sky, such as the shape of clouds. But, soaring birds are the most reliable indication to which we become attuned. It's possible to climb and glide over and over in the right weather conditions, staying aloft for hours and covering hundreds of miles. It's possible, and quite challenging, for glider pilots to race against each other over these hundreds of miles. It's a popular enough sport that races are held all across the country each soaring season, worldwide.
It's the first half of the first leg of a race in Cordele, Georgia, and I find myself low and in need of a climb. It usually takes me more time to get myself in trouble, but today I've left the Start Gate, and I'm quickly low. This isn't very reassuring. I maneuver my glider over ground features that might have heated enough to generate the thermal I need. No luck. I'm gliding and descending through calm, smooth air looking for the surge I will feel in the seat of my pants that will lift me and keep me airborne. If I don't find a thermal, I'll be on the ground in about ten minutes. I have a nice, paved county airport within my gliding range for safety's sake, but I'd rather race than sit on the ground. Frustrated, I ask aloud to only myself in the cockpit: "What's a guy got to do to get a little help around here?" I glance to my right, and there's the help I requested! Three or four Turkey vultures were circling together, and they were not flapping; they were climbing! I maneuver into the thermal under them and feel the bump as I enter the rising, buoyant air. I bank my glider steeply and climb, thankful that they've "marked" an excellent thermal for me. Reaching 8,000 feet, I continue the course, finishing the race that day about three hours later.
In another race, and I'd been flying for hours. It's mid-September in the Blue Ridge Mountains near the glider port at New Castle, Virginia. My competitor-friends and I had been racing over the green, tree-blanketed ridges, all having the times of our lives! But, the sun is low, no longer providing much heat for thermal lift. It is late in the afternoon. As the chances of finding a thermal decrease each minute, I descend to the top of the ridgeline closest to the glider port. There are still thirty miles remaining in the task, and I calculate that I'll need to climb to 6,300 feet to make it safely from there. With less than 3,000' showing on my altimeter, I must find a lift or give up the race and land now. I maneuver to a cup-shaped ravine in the ridge that might catch the wind and trigger a thermal off the rocks still warm from the lowering sun. The cupped area doesn't work, and I'm about to give up and turn for the safety of New Castle when I see the hawk. He's a Red-tail, circling and climbing just a bit farther down the ridge. I turn in his direction, join his thermal, and we rise together slowly to 6,300 feet. I leave the weakening thermal and finish the task, with my warmest regards to the hawk.
To be continued next month for a special 'Soaring with the Eagles' blog by Dennis.
9/24/2021 11:48:15 am
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Dennis Linnekin is Patricia Linnekin's (an HRC team member) husband, and a devoted supporter of HRC's mission and vision, as well as a stellar pilot of all sorts.