Determining free flight performance by surveying engineering techniques

Time aloft and distance traveled in free flight with a paraglider are determined by three factors: weather conditions, pilot skill, and paraglider performance. The latter factor can be represented in a performance curve. To construct an accurate performance curve, a surveying engineering approach was applied. Sensors (a variometer and a wind speed indicator) were first calibrated by Global Positioning System receivers. A test flight was then carried out with a paraglider which was launched to an altitude of 750 m using a stationary winch. After release, the variometer and wind speed indicator logged vertical velocity and horizontal velocity, respectively, for different angles of attack of the paraglider airfoil. This data, corrected for atmospheric conditions, was analyzed, via least-squares adjustment mathematical models, to determine an accurate performance curve.