Thermaling a Paraglider

Ill Start by trying to share the experience. Scroll down fo the How-to.

Well it happened. Just a few short weeks after completing my paragliding course, I was brimming with enthusiasm. I had just a couple of hours experience ridge soaring, having been protected from the hotter parts of the day by cautious instuctors and safety officers.

  Today was different, The breeze was moderate and a little gusty, some small cumulus clouds and some higher stratus clouds peppered the sky.

An uneventful takeoff and I turned towards the pocket in the ridge which regularly provided the lift to the ridgetop. I noticed that my wing was moving around more today, not uncomfortably, but every now and then it would kick a little. I simply paid close attention to my pitch control. I soared above the ridge a little, staying at around 150ft above the ridge, that put me at about 600ft above sea level. OK so Im not breaking any altitude records yet!

I decided to descend to attempt another top landing... I know Im not supposed to yet, but I like a challenge. I did a high pass, about 100ft above launch, then as  I turned my paraglider to prepare for another pass, my paraglider wing gave a hefty jolt. First to one side, then back. I was used to this movement, but I noticed a definite difference in intensity. "control the surge" I thought to myself as the wing shuddered. My vario had just noticed what was happening(its old and a bit slow to react.) But it has started screaming at me. It was beeping faster than my short flying experience had ever heard before. I looked towards the landing/launch and it was noticably getting further away...FAST!

It felt like I had entered an invisible elevator. I could not see the walls, and I could not see the entry or exit. The wind and screaming vario was all that I was aware of, focusing intently on keeping the paraglider wing above me. I glanced at my vario, 900, 1000, 1100, 1200, 1300 1400 feet and rising...

Then as suddenly as it had started, my wing gave a sudden surge and started flying faster. I seemed to be flying faster and sinking faster than usual (and I was). I had been evicted from the thermal. I gathered my thoughts and turned back towards the invisible tower of air. After a little hunting, I relocated it and up I went again. Not so high this time, but my ground crew had radioed that they wanted to leave.

Reluctantly I turned my wing towards the launch/top landing and began my descent. After a slightly rocky ride, I fluked another perfect top landing. I was shaking all over(the adrenalin shake)... MY FIRST THERMAL- AWSOME!

 

 How to thermal a paraglider

Thermaling is an art form. Less a direct process than a feel for the air. What I mean by this is that there are some things to look out for, but some pilots say they can feel the change in temperature, or smell the dust in a thermal... I cannot.

A thermal is a body of air moving upwards, because it is warmer and therefore less dense than the surrounding air. Thermals vary is size and speed. They originate from the ground when the sun heats a section of earth. The air in close proximity to this warm earth also gets heated. For now the air is often trappped there by the cooler air on top.

A trigger is required for the air to start moving upwards. Triggers can be a car passing on a hot road, a tractor, some children running around or a gust of wind made turbulent by a landform or trees. This way thermals often rise off prominent landforms.

Some explain this concept by imagining that the earths surface was flipped upside down and was now over our heads. Spray the surface with water, and see where the water drips off - those points will likely be the source of thermals...but not always.

As a paraglider pilot soars the skies, they are required to find a heat source and then a trigger. That is the most likely spot to find a thermal.

Moving skywards, the end result of a thermal is often a cloud (but not always). Only if the dew point for a given temperature and humudity level of a mass of air is reached, then clouds will form.

Clouds have a building phase then a stagnant phase, then they sometimes dissipate. Paragliders need to find the clouds that are in the building phase which usually lasts around 20 to 30 minutes.

So, find a cloud thats building, find the heat source and trigger on the ground somewhere upwind of the cloud, and there should be a climbing tower of air between the two.

Exceptions occur when the wind is strong and the thermal can be broken up into "bullets" making for a very bumpy ride.

A big beware: in highly unstable conditions, thermals can "overdevelop" into thunderstorms. When powerful thermals punch through an inversion layer(air on top significantly colder than underneath), the thermal will accelerate to phenomenal speed and can reach altitudes of 60,000 feet. Dont go anywhere near these. They can suck from miles around and the results are not good.

 

What to do when youve found one.

There is an unmistakable feeling of flying into a thermal.

Straight entry: The upward rushing air current strikes the leading edge of the wing and kicks it backwards. The wing then corrects itself by shooting forwards-and action which needs to be arested with the application of some brakes.
Sometimes as one gets near a thermal, the air is a little turbulent. This is because air around the thermal is often sinking. Once in a thermal the paraglider pilot needs to stay in it.

Side entry: If one wingtip enters a thermal, the wing will often lurch away from the thermal. This is because the wingtip that has entered the thermal suddenly has much more lift. The paraglider pilot needs to apply weightshift towards the lifting wing and turn into the thermal. Good feel for the wing helps here.

Falling out is also easy: As we approach the edge of a thermal, a wing tip may exit. This tip can lurch sideways or tuck, so weight shift into the good side and keep turning into the core.

In a straight exit, the wing will often overshoot forwards as we enter an area of sinking air. Many pilots apply some speed bar after exiting in order to get out of the sink band quickly without losing too much height.

It is wise the enter and exit the sides of a thermal relative to prevaling winds. The downwind side has the heaviest sink...closest to the strongest lift.

There are some simple rules for thermaling and ridge soaring. These are not rules of the air, but rules to stay up longer.

1. Turn in lift - Turning a paraglider dramatically increases your rate of sink,so its good practice to only turn in lifting air to minimise height loss.

2. Use weight shift - Where possible, use weight shift in preference to brake input. It makes for a more efficient turn.

3. Always have a small amount of brake applied - this preloads the wing and can minimise collapses in turbulent air. How much? About 5cm

 

More thermalling tips here

Please leave comments and suggestions in the blog under the hello parapilots or wing review section. Cheers