Tells some history about Radio-controlled model

in Small-business

Radio control has been around since Nikola Tesla demonstrated a remote control boat in 1893. World War II saw increased development in radio control technology. The Luftwaffe used controllable winged bombs for targeting Allied ships. During the 1930s the Good brothers Bill and Walt pioneered vacuum tube based control units for R/C hobby use. Their "Guff" radio controlled plane is on display at the National Aerospace museum. Ed Lorenze published a design in Model Airplane News that was built by many hobbyists. Later, after WW2, in the late 1940s to mid 1950 many other R/C designs emerged and some were sold commercially, Berkeley's Super Aerotrol, was one such example.

Originally simple 'on-off' systems, these evolved to use complex systems of relays to control a rubber powered escapement's speed and direction. In another more sophisticated version developed by the Good brothers called TTPW, information was encoded by varying the signal's mark/space ratio (pulse proportional). Commercial versions of these systems quickly became available. The tuned reed system brought new sophistication, using metal reed switches to resonate with the transmitted signal and operate one of a number of different relays. In the 1960s the availability of transistor-based equipment led to the rapid development of fully proportional servo-based systems, again driven largely by amateurs but resulting in commercial products. In the 1970s, integrated circuits made the electronics small, light and cheap enough for multi-channel fully proportional control to become widely available.

In the 1990s miniaturised equipment became widely available, allowing radio control of the smallest models, and by the 2000s radio control was commonplace even for the control of inexpensive toys. At the same time the ingenuity of modellers has been sustained and the achievements of amateur modelers using new technologies has extended to such applications as gas-turbine powered aircraft, aerobatic helicopters and submarines.

The first general use of radio control systems in models started in the late 1940s with single-channel self-built equipment; commercial equipment came soon thereafter. Initially remote control systems used escapement, (often rubber driven) mechanical actuation in the model. Commercial sets often used ground standing transmitters, long whip antennas with separate ground poles and single vacuum tube receivers. The first kits had dual tubes for more selectivity. Such early systems were invariably super regenerative circuits, which meant that two controllers used in close proximity would interfere with one another. The requirement for heavy batteries to drive tubes also meant that model boat systems were more successful than model aircraft.

Crystal oscillator superheterodyne receivers with better selectivity and stability made control equipment more capable and at lower cost. The constantly diminishing equipment weight was crucial to ever increasing modelling applications. Superheterodyne circuits became more common, enabling several transmitters to operate closely together and enabling further rejection of interference from adjacent Citizen's Band voice radio bands.

Soon a competitive marketplace emerged, bringing rapid development. By the 1970s the trend for 'full-house' proportional radio control was fully established. Typical radio control systems for radio-controlled models employ pulse width modulation (PWM), pulse position modulation (PPM) and more recently spread spectrum technology, and actuate the various control surfaces using servomechanisms. These systems made 'proportional control' possible, where the position of the control surface in the model is proportional to the position of the control stick on the transmitter. If you like it, you can click here china rc model.

In the early 21st century, 2.4 gigahertz (GHz) tramsissions have become increasingly utilised in high-end control of model vehicles and aircraft. This range of frequencies has many advantages. Because the 2.4 GHz wavelengths are so small (around 10 centimetres), the antennas on the receivers do not need to exceed 3 to 5 cm. Electromagnetic noise, for example from electric motors, is not 'seen' by 2.4 GHz receivers due to the noise's frequency (which tends to be around 10 to 150 MHz). The transmitter antenna only needs to be 10 to 20 cm long, and receiver power usage is much lower; batteries can therefore last longer. In addition, no crystals or frequency selection is required as the latter is performed automatically by the transmitter. However, the short wavelengths do not diffract as easily as the longer wavelengths of PCM/PPM, so 'line of sight' is required between the transmitting antenna and the receiver. Also, should the receiver lose power, even for a few milliseconds, or get 'swamped' by 2.4 GHz interference, it can take a few seconds for the receiver - which, in the case of 29cc engine, is almost invariably a digital device - to 'reboot'.

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Tells some history about Radio-controlled model

This article was published on 2011/09/22