Dennis Pagen is a legend in flying circles. He’s written a dozen books and some 400 articles on free flight, and is as interested now in the sport and its various disciplines as he ever has been (he started flying in 1973). This short clip shows him measuring sprogs, which is what he has been doing all morning here in Laragne.
Sprogs are important to the safety of hang gliders – they help control a glider’s stability. The reason they are measuring them all here at the World Championships is to make sure they are all set to within safe limits.
Pilots interested in sprogs can read more here, on the British Hang Gliding Competitions site:
“There are concerns that many pilots are competing with sprogs set too low, improving their glide performance but compromising the glider's pitch stability. As a result there isn't a level playing field: pilots that are prepared to accept a lower safety margin gain a competitive advantage”