A radio-controlled aircraft (often called RC aircraft or RC plane) is a small flying machine that is controlled remotely by an operator on the ground using a hand-held radio transmitter. The transmitter continuously communicates with a receiver within the craft that sends signals to servomechanisms (servos) which move the control surfaces based on the position of joysticks on the transmitter. The control surfaces, in turn, directly affect the orientation of the plane. Flying RC aircraft as a hobby grew substantially from the 2000s with improvements in the cost, weight, performance, and capabilities of motors, batteries and electronics. Scientific, government, and military organizations are also using RC aircraft for experiments, gathering weather readings, aerodynamic modeling, and testing. A wide variety of models, parts, and styles is available for the DIY market. Nowadays, distinct from recreational civilian aeromodelling activities, Unmanned aerial vehicle (drones) or spy planes add a video, GPS or autonomous feature, enabling instrumental RLOS or BLOS capabilities, which are used for public service (firefighting, disaster recovery, etc.) or commercial purposes, and if in the service of a nation's military, may be armed. History The earliest examples of electronically guided model aircraft were hydrogen-filled model airships of the late 19th century. They were flown as a music hall act around theater auditoriums using a basic form of spark-emitted radio signal. The British drone weapons in 1917 and 1918 evolved and their development continued through the work of the Royal Aircraft Establishment resulting in the fleet of over 400 Queen Bee UAV Target Aircraft in the 1930s. During World War II, the U.S. Army and Navy used radio controlled planes called Radioplanes as artillery target drones. The National Model Aviation Museum located in Muncie, Indiana hosts the world's largest collection of RC aviation history. They display models from every era of RC donated by the RC community around the world. They also have kit plans (aircraft blueprints) that RC pilots can purchase to build models from every era. The museum is located on the same grounds that the Academy of Model Aeronautics main office is located. Types There are many types of radio-controlled aircraft. For beginning hobbyists, there are park flyers and trainers. For more experienced pilots there are glow plug engine, electric powered and sailplane aircraft. For expert flyers, jets, pylon racers, helicopters, autogyros, 3D aircraft, and other high-end competition aircraft provide adequate challenge. Some models are made to look and