Soaring in the Alps

Printer-friendly versionPrinter-friendly version

Here is another report from Thomas van de Velde about his yearly excursion to St. Auban - the French Soaring Center in the French Alps.

Pushing Harder


This year was my fifth visit to St Auban, France’s national soaring center, and world-renowned destination for Alpine soaring. I left last year’s visit with a great sense of accomplishment. I completed my first solo 400+ point flight in the Alps, got checked out on a JS-1 high performance glider, and finally was able to find my way around the southern Alps. I felt pretty good about myself. All of that changed with this year’s “optimization” course. After completing the “basic” level during my first couple of years, this year’s graduation from “advanced” mountain soaring to the “optimization” level opened my eyes to a new set of challenges and - as of yet - a new set of goals to achieve. Continuing a tradition of sharing what I’ve learned at the CNVV, in this article I present some of the different optimization techniques I applied during my flying, discuss the mental adjustments to make when transitioning to the next level of performance, and share my “homework assignments” to prepare for next year’s visit. 


Let me start by introducing Manu, my instructor for this year’s course. Manu is a fighter pilot in the French Air Force. When not flying jets, he spends his time in the backseat of gliders teaching French Air Force cadets. Manu - who sharpened his soaring skills as a young competition pilot with the likes of Eric Napoleon, current French national soaring team coach - is an incredible instructor. He took me beyond leisurely cross-country flying and instead showed me how to work hard to optimize my flying.


Monday started as a typical first day at St Auban. I flew for a couple of hours with Manu in a brand new Arcus to make sure I could find my way around the area without putting myself in danger. Having passed that bar, I was given the green light to fly one of the center’s ASG-29s - a glider similar to the JS-1 with minor differences in wing stiffness  (A stiffer wing is preferred by some as it provides better sensory input). Personally I preferred the ASG-29 with its comfortable cockpit. Weather conditions on our first day were challenging at best. A low pressure system was gradually building over southern France blanketing the sky with thickening Cirrus. We managed to stay afloat in a mix of weak ridge, wave, and convergence - long enough to eventually escape for a quick stop at the Pic de Bure, north of St Auban. This was my first lesson: You have to be patient and work hard as it may pay off. The second day proved much better. We flew again in duo to cover the area of Castilanno and further north up towards Grenable. On the second day I got back in the groove of flying with flaps. Manu started to focus my attention on a first set of optimization techniques. 


You may have heard about the “count to 3” tip for turning into a thermal. I don’t  use this technique as it only works under ideal conditions and even then it may place you outside the strongest part of the thermal. I typically wait until I feel the strongest part of the rising air to start my turn. This is a good technique when you are pretty sure you’re heading towards a strong thermal (e.g. nice dark flat base). In strong/narrow mountain thermals you need to be more aggressive. When you feel a sudden push under your wing, you need to turn *immediately* to at least a 45 degree bank angle. It requires sharp focus to distinguish between a mere bump and a strong thermal’s push - something I am still struggling to get right. Manu: “Why didn’t you take that thermal?” Me: “What thermal?” Throughout the week I had to make these decisions dozens of times and react quickly when I got it wrong.


If your turn is not confirmed by a positive vario, you need to quickly push the nose down to regain speed, level off and head back on course towards the next thermal. Here I would again level off first and to then regain speed - possibly losing altitude in sinking air. This brings me to the second point: Prioritize setting your bank attitude over adjusting for ideal thermalling speed. I had a tendency to slow down too much before and during the initial thermal entry turn. While you want to slow down eventually, you should first and foremost throw yourself in the thermal. If you slow down too much before setting your bank attitude, you reduce your roll rate, stretch your turn radius, and end up risking missing the core. The reduced speed also reduces your glider’s responsiveness. It’s important to retain quick control input during the first couple of turns so you can make rapid adjustments to place yourself in the core. I’ll add two more tips related to this point: 1) On a flapped glider, don’t worry about lowering your flaps during initial roll in the core. Get the attitude set first and then adjust flaps and speed. 2) When releasing from tow, wait until you’ve entered the core before raising your landing gear. This assumes you’re getting off tow in a thermal - something you always want to aim for.


With regards to centering, the textbook technique of leveling off for a couple of seconds at the 90 degrees point ahead of the strongest part works fine as a rule of thumb to get started. At the next level of performance you have to work a little harder to get that good climb rate. As discussed before, the initial turns are more aggressive. The goal is to quickly find the core. This may require some big shifts to sample the air, build a mental model of the thermal’s shape, and locate the strongest part. Once you find the core (as indicated by a full circle of positive vario), you make small adjustments at the lowest sink speed for your bank angle. Applying slight top rudder to reduce aileron drag, you increase your bank angle in the strongest lift and reduce the bank angle in the weaker part of the lift until you have a consistent vario. Even with a consistent vario, you can try to optimize more by further increasing your bank angle until you hit the strongest part. This isn’t necessarily a comfortable flight situation. High Gs, turbulence, and constant focus can be draining. Manu clearly wasn’t satisfied with my leisurely climb performance. He asked me to push to the point where I felt uncomfortable. The hard work did pay off as we’d often outclimb others banked at 30 degrees. While you’re working hard on that climb, you also need to keep an eye out for what’s happening around you. Are others climbing faster under a different cloud? There’s no point in getting married to a perfectly centered 2 kts thermal when somebody else hits 4 kts nearby. 


At some point during the ascent, climb performance may start to degrade. As long as you’re above the climb rate average for your MacCready, you may want to continue to climb. However you don’t want to linger around just to reach cloud base. Note that softening may happen several hundred feet below cloud base. (Leaving well below cloud base has the additional benefit of better visibility of energy lines: cloud streets, conversions, etc.). When leaving the thermal you want to accelerate to cruise speed during the last turn. Ideally you exit the thermal at cruise speed, which requires acceleration at the start of the last turn. This way you avoid transitioning through the thermal’s sink area at lower speed. Between thermals you want to look for energy lines. These can be cloud streets, little puffs of condensation, differences in cloud base between two air masses, late day valley convergence, or any source of dynamic lift. You don’t want to simply look for the next big cumulus but also look for anything that improves your glide ratio during transition to that next cloud. 


The next point is going to sound obvious but you need to fly fast between thermals. I bring it up because in the mountains it may feel more comfortable to slow down and stay close to cloud base. While this is the right (safe) mindset for a beginning XC mountain pilot, when you start optimizing your performance you need to be comfortable flying faster in your “performance” band. What does that mean? Your performance band is the zone where you can focus on performance optimization vs navigation. You know where you are without a map or GPS, you’re comfortably within reach an airfield, etc. When you leave the performance band, you start to slow down and optimize for regaining altitude and staying within reach of an airfield that may not necessarily be on your desired course. Advanced pilots can stretch this performance band by leveraging “reliable” lift sources that can act as “fill up stations” along the route. In the Alps (like in the Cascades) there are several consistent lift sources that are well know by the locals. The Guillaume is known to always work above the tree line with south wind, the Parcours offers miles of ridge lift - a virtual highway in the sky, the Barcelonnette valley convergence against the Tête de Siguret, etc. Experienced pilots use these points in their decision making to push the performance band. Knowing these points allows you to fly faster and be pickier about the thermals you take. A less experienced pilot will not know about these points and may have to leave the performance band sooner to focus on staying high. This is where local knowledge really gives you a leg up! 


Beyond these techniques, I want to add a note on the mental state of the pilot when focusing on optimization. In prior years the focus was primarily on navigation and discovery (as well as safety, flying technique, etc). There was plenty of time to take in the beautiful views, amazing mountains, and discovering new areas. When the focus is on optimization, the physical effort goes up significantly. It can be quite exhausting to always be on your toes. During most of my flights, Manu combined a little bit of “discovery” and “optimization.” For example, one wonderful day I flew the Arcus through the southern Alps sector on the way to the Mont Blanc. Manu took over in the northern Alps sector - giving me a moment to rest and take pictures. On the way back, we focused again on “optimization” - pushing on all the aforementioned techniques for the entire flight back to St Auban. Back at St Auban, I was ready to drop the landing gear and call it a day. Not so fast! Manu pushed me to fly back north to see how I’d optimize my flying during the late hours of the day in weaker conditions. I admit I was pretty exhausted when we finally touched down. The cold beer waiting at the bar tasted great!


So what’s next? If everything aligns, I am a year away from my next trip to St Auban. In the meantime, I want to apply what I’ve learned by pushing a little harder during my flights. Instead of maximizing OLC points based on flight tracks that take me through the most favorable flying conditions, I may elect to set a predetermined goal and stick with it to learn how to adjust my flying style in different conditions. Per Manu’s suggestion, I also plan to load up my glider with water on weak days to challenge my thermalling skills and get an opportunity to fly faster. I was told the Discus b does pretty well with water in the wings. We’ll see...