Radio-controlled aircraft (also called RC aircraft) are small aircraft that can be controlled remotely. There are many different types, ranging from small park flyers to large jets and mid-sized aerobatic models. The aircraft use many different methods of propulsion, ranging from brushed or brushless electric motors, to internal combustion engines, to the most expensive gas turbines. The fastest aircraft, dynamic slope soarers, can reach speeds of over 450 mph (720 km/h) by dynamic soaring, repeatedly circling through the gradient of wind speeds over a ridge or slope. Newer jets can achieve above 300 mph (480 km/h) in a short distance.