The Real Reason Paragliders Stay Up
There is a widely held but inaccurate belief that paragliders are held aloft by aerodynamic forces. Nothing could be further from the truth.
Paragliders are held aloft by electrostatic repulsion. The canopy is charged with static electricity. This charge repels the ground and keeps the canopy in the air. This charge is also responsible for the rigidity of the wing and the apparent ‘inflation’ of the individual cells as various components of the canopy repel each other.
The initial static charge is produced by friction with the ground that occurs as the pilot ‘build the wall’ or ‘inflates the canopy. That’s why it’s easier to launch from certain types of terrain -- some types of ground surface generate more static electricity than others. The charge is maintained by friction with dust particles and aerosols in the atmosphere. Paragliders ascend in thermals because these contain more dust. They descend in sink because -- particularly underneath clouds -- sink contains water droplets that ‘ground’ part of the static charge.
Canopy collapses occur when the static charge shorts out over part of the canopy. This shorting is also responsible for the ‘crackling’, ‘rustling’, or ‘snapping’ sounds that are often associated with canopy ‘collapses’ and ‘re-inflations’.
It is easy to demonstrate that this explanation is correct. If you construct two identical canopies, one made of conventional fabric and the other made from some conducting material such as steel or lead, you will find that the fabric canopy flies much better than the metal one.
I hope this information has been of some help to aspiring pilots.
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Last modified: 25 September 2009