Friday, 11 May 2007

Thermalling Gliders: an Iterative Process

Gliding appears to an outsider as just taking a glider into the air and flying around. I reality there is a fight going on up there: to stay up in the air. Without any rising air the glider would be forced to land within a few minutes.


So how to stay up ? You have to find a thermal ! A thermal is basically a column of rising air that you try to stay in by making circles. This continuous circling is for the passenger in a glider not the most exiting part as very soon the stomach will start to protest !

The thermals may be marked by a cloud, but this is not always the case. After you have found the thermal, you not only have to stay in it, but you also have to find the area with the strongest lift. This is done in a number of iterative steps that will bring you to the center of the thermal. After every turn you make a mental picture of the lift division you encountered, and according to this you correct you circle so that you will fly into a stronger lift. After this circle you start all over again: making a mental map of the thermal, correcting you circle and look if things improve.

As you climb in the thermal, the shape and the lift division of the thermal can change considerably. This can result that all the way up in the thermal you are to correct your flight path. The iterative process goes on and on !

But whatever us human beings develop, compared to the birds we are just amateurs, and they are the professionals. When looking for thermals, the best thing you can do is to try to spot a bird. If you spot one it is usually for just a few seconds because it quickly outclimbes you ! The picture below shows a very rare picture of a glider and a bird thermalling together.


As the saying goes in Latin: “Natura Artis Magistra” which translates as 'Nature is the Teacher of Art'

1 comment:

Maurits said...

Hi Martin, congratulations with your interesting new blog! I will follow your publications with interest. Kind regards, Maurits