With each generation of materials and with the improvements in aerodynamics , the performance of gliders has increased . One measure of performance is the glide ratio . A ratio of 30:1 means that in smooth air a glider can travel forward 30 meters while losing only 1 meter of altitude . Comparing some typical gliders that might be found in the fleet of a gliding club – the Grunau Baby from the 1930s had a glide ratio of just 17:1 , the glass-fiber Libelle of the 1960s increased that to 39:1 , and modern flapped 18 meter gliders such as the ASG29 have a glide ratio of over 50:1 . The largest open-class glider , the eta , has a span of 30.9 meters and has a glide ratio over 70:1 . Compare this to the Gimli Glider , a Boeing 767 which ran out of fuel mid-flight and was found to have a glide ratio of 12:1 , or to the Space Shuttle with a glide ratio of 4.5:1
Gimli Glider
Gimli Glider
Glider (sailplane)