Remote Control Helicopters:

Remote Control Helicopters are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training. Several basic designs of remote control (RC) helicopters exist, some more maneuverable than others (such as helicopters with collective pitch). The more maneuverable designs are often harder to fly, but benefit from greater aerobatic capabilities.

Flight controls allow pilots to control the collective and throttle (usually linked together), the cyclic controls (pitch and roll), and the tail rotor (yaw). Controlling these in unison enables the RC helicopter to perform most of the maneuvers an aeroplane can do, and many that aeroplanes cannot, such as hovering and backwards flight; in this manner, they are quite similar in operation to full-sized helicopters.

The various helicopter controls are effected by means of small servo motors. A piezoelectric gyroscope is typically used on the tail rotor (yaw) control to counter wind- and torque-reaction-induced tail movement. This "gyro" does not apply a mechanical force, but rather, electronically adjusts the control signal to the tail rotor servo.

The engines used are typically methanol-powered two-stroke motors, but gasoline, jet turbine and increasingly electric brushless motors combined with a high-performance lithium polymer battery are also used.

Recent advancements in battery technology make electric flying more feasible in terms of flying time. However, these lithium polymer batteries can explode upon overheating. U.S. Consumer Product Safety Commission Recall Alert.

In the past electric RC helicopters were used mainly indoors due to the small size and lack of fumes. Larger electric helicopters suitable for outdoor flight and advanced aerobatics have become a reality over the last few years and have become very popular. Their quietness has made them very popular for flying sites close to residential areas and in places such as Germany where there are strict noise restrictions. Nitro helicopters have also been converted to electric power by commercial and home made kits.

The smallest remote-controlled production model helicopter made (Guinness World Records 2006) is the Picoo Z sold at many toy stores, electronics stores and internet stores, costing about $30 (£15). The next smallest is the Mosquito counter-rotating blade helicopter, which is also a battery-operated R/C helicopter.

The smallest non-production remote-controlled helicopter is the micro flying robot, developed by Seiko Epson in 2003. The robot is only 2.8 inches (70 millimeters) tall and weighs only 0.31 ounces (8.9 grams). The initial model required an external power source connected by wires; an improved model developed in 2004 weighs 0.43 ounces (12.3 grams) including battery and is capable of three minutes of independent flight.

Although RC helicopters are generally used by hobbyists for recreational purposes, they are sometimes used in applications such as aerial photography, filming, and remote observation or inspection. Some companies make RC helicopters specifically for these uses.

Remotely piloted or autonomous helicopters powered by electric motors instead of by gasoline or diesel internal combustion engine, with electricity provided by fuel cells or batteries include a type of small unmanned aerial vehicle (UAV) which can carry 10 pounds weight of payload.