New materials such as carbon fibre, and carbon kevlar have since been used with computer-aided design to increase performance. With each generation of materials and with the improvements in aerodynamics, the performance of gliders has increased. Modern flapped 18 meter gliders such as the ASG29 (pictured below) 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.
Most gliders require assistance to launch, though some have an engine powerful enough to launch unaided (Self Launching Motor Gliders). In addition, a high proportion of new gliders have an engine which will sustain the glider in the air, but is insufficiently powerful to launch the glider. The engines can be petrol, jet or more recently electric.