Paragliding 101

If you are paraglider pilot, you will like this.

        My favorite part of flying is undoubtedly thermalling; in fact, thermalling may be my favorite thing to do in life. There’s nothing like hooking a sharp-edged, positive ripper of a thermal and riding it upward for a  couple of miles. My least favorite part of  flying is also thermalling; those days when everyone else goes up flying straight and you hit the deck like a dropped park bench--repeatedly. On those days you’re glad you landed alone so no one else can hear you scream. The following is my latest “thermalling system.” I hope it helps you develop yours.

Thermal Theory

        A little more thermal theory is useful to understand how to fly them. I believe thermals close to the ground are often quite small and relatively violent. As they rise they tend to smooth out and expand. Pressure also tends to influence thermal formation; high-pressure days tend to produce smaller, sharp-edged, “punchy” thermals. Lower-pressure days can produce very strong thermals obviously, but they tend to have mellower edges and be larger in size.

        The day’s lapse rate also influences thermal strength; a  hot day with a very strong lapse rate will produce stronger thermals. Think of a very warm piece of air rising out of a collector on a day with a strong difference in air temperatures between the ground and say 5,000 feet above it. A thermal will rise quite quickly in this situation. An inversion is the opposite, and not surprisingly thermals usually stop or at least slow down at inversions.

        The above factors (and hundreds more but this is a start) give each day its thermal “profile.” If you launch on a clear blue day (indicating high pressure) with a good lapse rate (you checked the day’s soundings), then you might expect sharp-edged, strong thermals. If, however, the sky is filled with soft cumulus and looks somewhat hazy  due to moisture, then you might expect softer thermals. The first thermal of the day provides some good clues about what’s happening; if it rips you upward and all you have to do to stay in it all the way to base is turn a bit then you’re off to a good start. If it’s small and difficult to stay in then ends abruptly 1000 feet later and you can’t take it any higher, then you know the day will be more difficult. I take a mental note of three important characteristics with each thermal I use during the day. What is my average climb rate? Not the spikes, but the true climb rate as expressed by a 20-second average? How high do I get before it totally falls apart, and are there any altitudes that seem tricky to keep climbing through? And finally, what are the size and drift of the circles I’m making?

        The climb rate tells you what to expect as the day progresses; climb rates tend to improve until late in the day, and thermal size also tends to increase as the day wears on (sink too unfortunately). If you’re getting solid 600fpm climbs, then it’s probably not worth stopping in 100fpm on a glide unless you’re low (anything going up when you’re low is great). The peak thermal altitude is also useful; if you are getting to 6,000 feet AGL consistently but a strong thermal suddenly “stops” at 4,000 AGL then you’ve probably lost it and should search for it. However, if the thermal stops at 5,800 feet then it’s most likely done and time to go on glide. Remember that the peak altitude of the thermals should increase as the day progresses. On good days in Texas it’s not uncommon to see thermals in the morning only reach 4000 AGL, then 6000 AGL at noon, 10,000 at 2:00 p.m. and 14,000 at 5:00 p.m. This progression is generally less in the mountains but still observable.

Finally, the size and drift of your circles at various altitudes also tells you what to expect on the next climb and information on wind speeds aloft. This tells you what angle your thermal will be flowing from a collector so you can intersect that line I (note-very strong thermals will have no problem pushing the wind around them like a bridge abutment in the river).

Credit to Will Gadd.

Ok got to go now. Going to go flying. Stay tuned for more #paragliding adventures.