25km triangle explained

Some commentary on my 25km triangle on Saturday;

The wind is easterly, the sun have been heating the SE and S facing ridges. To the east of the ridge the land is quite flat, with some smaller hills. With the sun and wind I expect the thermals to trigger just in front and on the top of the east side of the ridge. Some small whispy CU’s could be seen in the areas over the highest hills.

The task is a start point on the ridge, then 7 km SE to a TP near Hamnås, then 7km NE over hilly area and crossing over Øgderen lake to a TP on a small ridge there, and a 11km final glide back over Øgderen lake and flatlands before arriving over the ridge to the east of the airstrip. To set a new record I must arrive no more than 500 meters lower than I left the start point.

25km FAI Trogstad
I took off at 13:00, Truls towed me up to the ridge where we flew through some weak lift on the way, but there was nothing solid. I released at around 800 meters MLS over the most promising area, and started searching around. It was broken and turbulent, it felt like the thermals were trying to go through an inversion layer, but I could not see the typical layer of dirt in the air.

The whole area was turbulent and thermic, it was no problem staying up, but it did not go very high. I saw a tractor spreading fertilizer on a field a few km in front of the ridge, and flew closer to it when I could smell the thermals from that area. I could feel the smell in at least 5 different thermals, but none were solid enough to give more than 50 meters before slowing down.

I glided back to the ridge and found a nicer core that took me to 1000 meters for the first time, I took the start point and glided under a small cloud that seemed to come from a isolated hill in front of the ridge, but the cloud was gone before I could glide the 2 km there, and I found nothing good. Cloudbase seemed to be at least 2000m. Going back I found another core over some deforested area, and spent the next 10 to 15 minutes in the area gradually getting a little higher, but also losing altitude while searching around.

At 1400 meters I felt I was high enough to get to the first TP with some safety to get back to the airstrip if I could not find more lift. I started gliding without going back to take a new start time, something I would regret as the conditions on course would actually be much better than I thought.

Gliding the 5 km to the TP I stopped in another nice thermal that took me to 1550 meters and by now (13:55) the air started to feel much better than earlier in the day. I flew straight to the TP without losing much altitude, and hit a nice area with good lift just behind the TP. I left that area at 1800 meters feeling it was enough to complete the task with one more thermal on the way.

Liftstreets form on blue days too (blue cloudstreets), by flying into the wind in good areas it was possible to glide a few km while gaining altitude. Here is one screenshot from SeeYou where the red part of the tracklog is lifting air. This area is thermals triggering off the small hill where the TP is located.


From there it was a straight glide to goal. As the ridge was triggering lots of thermals now I expected some areas of sink close to the ridge, and found 3,5 m/s sink for quite some time before hitting better air just before the TP. I came in with 100 meters to spare, but way to slow for a new record due to spending lots of time getting high in the beginning. In retrospect I should have thermalled up again and done a second attempt, I believe it would have been quite fast in the good air.

I glided back to land at the airstrip and pack up next to my car with cold water and some food. It was a short task, but triangle flying is really rewarding. You get different challenges on the course, with cross, head and tailwind. And you land back where you came from, to the comfort and company at the airstrip.

Tracklog here;