Radio-controlled helicopter
Several basic designs of RC helicopters exist, of which some (such as those with collective pitch control) are more maneuverable than others.
Turbine helicopters are also increasing in popularity, although the high cost puts them out of reach of most people.
Typical flight time for nitro helicopters is 7–15 minutes depending on the engine size and tuning.
These were the Kalt Whisper and the Kyosho EP Concept, flying on 7–8 × 1.2 Ah NiCad batteries with brushed motors.
However, the 540-sized brushed-motors were on the limit of current draw, often 20–25 amps on the more powerful motors, hence brush and commutator problems were common.
In the past electric 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.
The system's simple direction control and freedom from torque induced yaw have, in recent years, made it a good candidate on small models for beginner and/or indoor use.
While a coaxial model is very stable and can be flown indoors even in tight quarters, such a helicopter has limited forward speed, especially outdoors.
Compensating for even the slightest breeze causes the model to climb rather than to fly forward even with full application of cyclic.
More recently, multirotor designs have become popular in both the RC hobby and unmanned aerial vehicle (UAV) research.
Because of the normal interaction of the various control mechanisms, advanced radios include adjustable mixing functions, such as throttle/collective and throttle/rudder.
Starting with the Spektrum DX6 park flyer transmitter system in 2006, RC flying began the departure from various lower frequencies which were subject to interference and were less reliable than the new spread spectrum protocols.
Systems such as Spektrum and JR use the DSM2 and later, DSMX direct-sequence spread spectrum (DSSS) method, where they transmit on a pair of fixed channels chosen when the radio and receiver are turned on.
Many modelers join a club so they can be instructed by experienced RC pilots, or follow on-line guides.
The cyclic and yaw controls are not by definition different in these two modes, though 3D pilots may configure their models to be much more responsive.
Models are typically purchased in kit form from one of about a dozen popular manufacturers and take 5 to 20 hours to completely assemble.
Additionally, the small size and low weight of R/C helicopters and their components means that control inputs, especially cyclic (pitch and roll) can have a very fast response, and cause a rotation rate much faster than the equivalent input might produce on a full-size aircraft.
To reduce mechanical complexity and increase precision of the control of the swashplate some model helicopters use cyclic/collective pitch mixing.
During 3D flying, helicopters perform advanced aerobatics, sometimes in a freestyle form, or in a predetermined set of moves drawn up by the organisers of the competition.
There are a number of 3D competitions around the world, two of the best-known being the 3D Masters in the UK and the eXtreme Flight Championship (XFC) in the United States.
US Federal Aviation Administration regulations from 2006 grounding all commercial RC model and unmanned aerial vehicle (UAV) flights have been upgraded to require formal FAA certification before being permitted to fly at any altitude in the United States.
Infrared radios have the disadvantage of potentially being interfered by sunlight or fluorescent lights,[15] making them more suited for indoor RC helicopters.
Safety precautions, proper maintenance, and an understanding of the mechanics and flight characteristics of the models are necessary to prevent accidents.
[20] In 2014, several organizations with interest in unmanned aircraft systems in partnership with the Federal Aviation Administration launched a new educational campaign to promote safe and responsible flying and provide guidance for hobbyists and commercial users.
