Existing comment:
HEAVIER-THAN-AIR FLIGHT
Heavier-than-air vehicles generally achieve flight with aerodynamic lift created by airflow over a surface (usually a wing). There were three basic types of early heavier-than-air vehicles -- kites, gliders and airplanes. Kites are unpowered, tethered craft. Gliders fly freely. Both kites and gliders are limited because they rely on the airflow provided by wind to remain aloft. Airplanes are powered air vehicles that use their own propulsion to create airflow over the wings. |