Glider

A glider is a heavier-than-air aircraft designed to fly without an on-board engine. Gliders rely on gravity during launch to gain airspeed and then use favorable air currents or thermals to remain aloft and travel forward over distances.

Design emphasizes high aerodynamic efficiency and lightweight construction. Most gliders have high aspect-ratio wings with smooth airfoils and a streamlined fuselage. Glide performance is described by the lift-to-drag ratio (L/D); modern sailplanes typically achieve L/D around 40:1 to 60:1, with higher-performance models capable of greater values. Pilots optimize speed for distance by balancing lift, drag, and the availability of rising air.

History shows gliding experiments dating to the late 19th and early 20th centuries. Pioneers such as Otto Lilienthal conducted systematic flight tests, contributing to the understanding of controllable, heavier-than-air flight. The Wright brothers also explored gliding concepts. By the 1920s and 1930s, tow-launch and winch systems enabled broader use, and advances in materials and aerodynamics spurred rapid development after World War II.

Operations and types: Gliders are used for recreation, sport, and training. They can be conventional sailplanes or self-launching variants with small engines. Launch methods include aerotow, winch, and bungee. They employ airbrakes or spoilers for descent control. Modern sailplanes use composites such as fiberglass, carbon fiber, and foam cores; wingspans commonly range from 15 to 30 meters.

Use and competition: Gliding emphasizes cross-country flight, navigation, and precision landings. Clubs and schools provide instruction and organize events; competition classes are based on wingspan and equipment, encouraging advances in performance, safety, and weather interpretation.