Devil’s Dyke is a deep V-shaped valley on the South Downs, about five miles north of Brighton. Tamara and I went there a few days ago, to see it and relax in the scenery. As it happened, we could see paragliders in the air as we approached, And it was clear that they were using the steep hill as a launching pad.
We got talking to a couple of the paragliders (people who paraglide) and learned a few things.
Before that day I had this idea that a person paragliding would just run down a steep hill and launch themselves into the air. That’s not how it works. In order to get off the ground they have to lean into the wind. and find a funnel of rising air that will lift them. Air is invisible, of course, so there is a knack to finding and holding the glider in position to take advantage of the rising air.
One of the people paragliding had a gadget with a little screen attached to his chest pack. He explained that it was his cheating machine (said tongue in cheek). It measures barometric pressure and tells him when he is standing below a thermal,
It makes a beeping sound, faster and louder when he is below a good difference in air pressure. He takes advantage of that and turns into the wind and that movement lifts him. As he rises, the thermal widens (it’s like an inverted cone of air) and so he turns more gently as he rises.
If the paraglider isn’t turned into the wind in the thermal, it wouldn’t rise at all.
It’s easy to imagine, but we watched another man who just couldn’t get it right for a while., He turned his paraglider, but time and time again one side of his wing missed the thermal and started to collapse on the leading side. A couple of times it came down too quickly, folded, and crashed into the ground.
One of his companions joked and said to remind him not to buy that wing. So I guess the crashing into the ground can weaken the material or the stays, something I never thought of.
And there are a lot of stays or leads – dozens of them – that connect the harness to the wing. And the pilot (is that a good name for a person who paraglides?) turns and pulls and changes the angle of attack of the wing by pulling cord that controls a bunch of stays.
Here’s a sequence of a man who was fighting the wind, trying to get in sync with a thermal. He did take off eventually, but not before his wing hit the ground a couple of times.
Tamara asked what the ideal weather was for paragliding and how long a person could stay airborne. The man she asked said that any weather is good, as long as the thermals are good – and it is possible to paraglide even when it is snowing. And when conditions are right, a paraglider can stay airborne for ten hours!