Short analysis of the TchinTchin flight on 15 December

[dgtfer]

A flight with unexpected consequences

The weather looked bombastic, with strong, wide thermals, ceilings above 2000m AGL and normal activity, combined with a 30km/h northerly wind. In C2 it was a flight averaging over 200km/h! And some of the pilots did turn at 170km/h, but flew very high over the mountains to the south of the track, whereas most of the pilots had the unpleasant surprise of out landing in the first 50km.
Here's the setting:

C2.JPG (40.48 KiB) Viewed 455 times

C3.JPG (44.46 KiB) Viewed 455 times

At the start we had a tiny bit of dynamic lift, which disappeared after about 20km. Those who continued on the slope fell irreparably and were ruined. On the other hand, a few pilots were lucky enough and had the presence of mind to hang on to the first service pump, and then realised that it was climbing hard and wide! To understand what this meant, I restarted the flight with the thermal aid activated:

Not the slightest thermal below 2000m, neither on the north faces, which is normal, nor on the south faces (downwind) which is much less so. The only thermals a little lower down (1500m all the same) are on the West faces. These thermals start very high but climb at more than 4 m/s. The wind below 1500m disappears, which again is normal, because of the relief of the Oberland massif which dominates us at more than 3000m and the slopes give almost nothing. What's more, the valley becomes narrower and narrower as you head east, which further increases the masking effect. On the south-facing slopes, there's a little positive airflow, but it's not enough to keep you aloft. This weather is rather paradoxical, as the fact that there's little or no wind in the lower layers shouldn't prevent the formation of thermals on the exposed faces. Let's hope this phenomenon will be corrected in a future version of Condor. In the meantime, it's imperative that Tasksetters check the actual thermal activity before launching a flight downwind of a mountain range. And of course, we'll always have to stay above the ridges...

[Paul_UK]

I noticed the same in a task I just posted up for a Christmas challenge task with VSC. I converted an old C2 task that was a low level high speed blast the whole way, through gated windows. It was originally created by someone else and many flew it over the years. In C3 it doesn't work though due to mountains upwind blocking killing the dynamic lift off on the ridges across the valley. I just changed a few windowed TPs to normal quadrant style TPs and now the pilots must find the optimum height to fly through these to achieve the fastest time. It is however most certainly a case of get up on top of the ridge lines or you're going to be in a field in the bottom of the valley.

My real life flying experience in mountains is pretty limited (7 days of flying) so I do not know how far off things are, if they are at all. We just have to adapt the way we fly for now, in C3, to ensure we complete the task. Whilst in C2 pushing really hard worked the majority of time in C3 the weather is certainly favouring those who fly a little more conservatively / fly to complete a task over those who just push push push. This works for me mostly fortunately, but is probably why I was never the fastest when flying in C2.