Introduction to Thermalling 

The best centering method I think is to use the vario. As the lift increases, flatten the bank angle and as it decreases steepen the bank angle. The greater the change in lift, the greater the change in bank angle. This method gets me into the best lift in usually 3 turns or less.

I´ve always wondered what the theory behind thermalling, especially centering, is, so thank you very much :))

Extremely helpful and well crafted Bill, Thank You!

great video!

Excellent video Bill!!

wow, such a detailed analysis

Excellent video! Thank you very much for posting this.

Thanks for this video

Really superb graphics and animation!

this was great, love the laid back presentation

This is great!

Excellent 2ZC

super useful content. thanks =)

Great video! After hundreds of hours trying to advance my thermaling skills, the Huth method worked the best. I will skid the glider a little in small strong cores also. It’s better to be inefficient in the strong lift than efficient in the weak lift. If you can’t stay in the lift, you might fall out of the bottom of the thermal.

Great video. Thanks for putting all those techniques together in one place. I’ve always been confused about whether to step in my bank or shallow out when encountering lift.

Thanks Bill for the video, very useful to look at the various methods of thermalling. In practice, I still rely mostly on feeling, sensing the thermal. The vario indicator may go up, but I only turn towards the lift when I feel that the updraft "carries" the airplane and provides enough lift. Greetings from the Netherlands, Marc

Thank you.

Bob Wander's Mentor series book "Breaking the Apron Strings" by Phil Petmecky describes another interesting method: "Shallow the bank, slightly, if the vario is rising. Steepen the bank, slightly, if the vario is falling. ... Steepen the bank, quickly and much steeper, if the vario is near the top of the best lift you think is possible."

Thanks for a great video. One detail is more complex than it appears though, which is 'sink around the thermal'. It's hard to know what a lay person (say the person currently programming thermals in Microsoft Flight Simulator) would make of those sink arrows on the diagram, although they do commonly appear. The most common misconception is air that goes up has to come back down, otherwise the people on the ground would suffocate and we know that doesn't happen. Not often enough to make the papers, anyway. We need to keep in mind the air that rises is expanding and cooling until its temperature matches the air around it. At that point, to a first approximation, there is no need for that air to go anywhere. The volume (~diameter) of the thermal is extremely small compared to the area of nominally non-rising air between the thermals so the air simply moving sideways (aka wind) is easily sufficient to 'backfill' the thermal. There are secondary effects such as the rising air condensing when it reaches cloudbase and that adding energy, and air descending from above to below cloudbase gets a similar boost on the way down (i.e. the moisture evaporates and takes energy out of the airmass so it speeds its descent). Those secondary effects are normally relatively small (as a UK soaring pilot I've done a lot of cloud climbs) and also any descending air has a much greater area to do that with than the relatively narrow column of rising air, so IMHO we have to be careful not to give the impression that the sink around the thermal is some kind of inevitable inverse thermal to balance the books. It might be that the sink we do experience is more to do with any rotating turbulent air around the thermal than a river flowing downwards. I do think your video is great, and I don't mean to crap on it with this apparent minor correction, but thermals are being programmed right now in MSFS and I'm fearful Microsoft will think every 6 knot thermal should be surrounded by 6 knots sink.

Pilots are often misguided by the display of a thermal: The seat pressure or the variometer give the impression that a thermal is present. However, it is often just a horizontal or vertical gust. With the HAWK software in conjunction with an LX9000 vario, it is possible to almost completely eliminate these false indications.My accuracy when flying into real thermals has increased significantly over the last 2 years thanks to HAWK.

A thermal will be surrounded by sinking air only in the absence of wind. In wind, the sink will be on the downwind side of the core.

Great stuff. Curious if any sailplane pilots have that experience of 'going over the falls'. It's something I've encountered a few times while hang gliding on days with strong thermals, there's a sharp contrast of lift (or lift/sink) at the boundary inside and outside the thermal; if you exit the thermal nose first it can feel like the glider is about to tumble (not a pleasant feeling).

I'm curious, whats the highest altitude you've seen birds at? Are they only helpful indicators down low (under 300')?

Would you comment on how to determine the ideal bank angle? I've found myself at lower angles (30ish) "looking for surge" for a long time, when maybe I should have been steeper and closer in.

👍

Why add 3 for 30 degree bank? Not 4?

I fly model rc. Gliders and I have learned the best skills from watching the true masters of flight, the birds...lol..

“Intro to thermalling” von Bill Palmer … wäre hierzu mein Videotipp als Segelflieger 😊 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-z4xKYfT6aJA.html Vielleicht kommen ja paar motorisierte Kollegen auf den Geschmack…ok bin auch gerne mit Motor unterwegs, ist manchmal entspannender … nicht immer möchte ich mir die Höhenmeter erarbeiten müssen…