I have decided that I may try a new series of Blog posts like the one for 3D Printers I did recently (currently on hold at 10 parts). This time it will be about Remote Control Model Cars or RC Cars for short with the first post trying to explain the basics of Electric RC model cars.
Radio controlled (or R/C) cars are battery/gas-powered model cars or trucks that can be controlled from a distance using a specialized transmitter or remote. The term "R/C" has been used to mean both "remote controlled" and "radio controlled", where "remote controlled" includes vehicles that are connected to their controller by a wire, but common use of "R/C" today usually refers to vehicles controlled by a radio-frequency link. - Wikipedia
Essentially a radio controlled car consists of two things, the car itself containing everything it needs to run as directed by the user as well as a radio transmitter or a remote controller that is used to give commands to the car. Depending on the radio receiver inside the car and the radio transmitter used you can get from a few meters to hundreds of meters operational range for control of the RC vehicle. The focus of this post are the Electric-powered RC model cars that rely on rechargeable batteries, I'll be doing a separate post explaining in more details the basics of Gas-powered models as well.
People that are not into RC modelism can often mistake RC toys with RC models or think that they are essentially the same things - toys for kids, but that is not true. There are a couple of difference that make RC models suitable for all ages and there are models so advanced that nobody will even dare to call them toys. So what are the main differences between the two? Well, toys are toys, they are cheap plastic models with very limited and basic Remote control functionality and without the ability to replace broken parts with spares or install upgrades.
RC model cars are much more complex than a toy, they are built from many different parts that are available as spare parts and can be purchased and replaced if you break them, there are also upgrades and tuning parts available. RC model cars come with more complex electronics that offers precise control and maneuvering capabilities and faster speeds in general. There are many different sizes and categories of RC model cars available, depending on the type of use and capabilities you expect - casual and racing models, on-road and off-road, electric-powered and fuel-powered and so on. As a result of course RC model cars are more expensive than a toy car, but they also offer much more than just a toy RC car.
Here is how a radio controller or transmitter generally looks like for an RC model, though there are a lot of toys that also come with similar looking controllers. The difference however is huge as the radio controller for RC model cars offers proportional and precise control of both steering and speed while a toy car usually has just two positions - stop and go as well as full left, center and full right. With the transmitters of RC model cars the steering and speed of the car depend on the level that the user wants and there are many intermediate states available between brake and max speed. As a result you are getting really precise control of the actions of the model, even when it is moving fast.
A typical RC model car transmitter comes with two main features - a steering wheel and a speed trigger. The wheel in the center controls how much the car will steer, you need to rotate it either left or right and depending on the position the RC car will steer by the respective command (the center position is for straight). The steering of the car in either direction is proportional to how much you have rotated the steering wheel of the transmitter. It is the same with the speed trigger it comes at a center position by default, meaning that car is standing at one lace and not moving. Pulling the trigger towards you will make the car move forward and pulling it away from you will act as a brake command (if already running forward) or will make the car go in reverse. The control is again proportional, so the actual speed of the car or the level of the brake depends on how much you pull or push the trigger of the transmitter.
RC model cars typically come with a universal chassis that can fit a lot of different bodies on top of it thus changing the look of the car in many different ways following the owner to customize it without actually having to buy a new model. The bodies are usually made from Lexan (flexible and thin Polycarbonate plastic material) as it is not very expensive and offers good flexibility and durability to last you for a while. The RC car bodies can be painted differently and furthermore decals can be applied to make them even more realistic. They can come in unpainted clear plastic for the user to paint them as he/she likes or can come factory painted and with applied decals and ready to be installed and used.
The two main goals of the body are to protect the chassis of the RC model car from damage when you crash as well as to provide an easy and nice looking way to change appearances. The bodies are easy to attach and remove from the main chassis of the car as you might have to tune something or change batteries. They are usually attached to the so called body posts of the chassis with the help of body clips, similar to how some big race cars use details that can be quickly attached and detached from the chassis. Here the scale is just smaller, but many of the things you have available are very similar or even the same as on big regular cars, they are just smaller in size.
The chassis itself holds everything, from the receiver needed to get commands from the remote control that the user is holding to the electronics (in this case) that controls and drives the car (more on that in a moment) as well as all the moving mechanical components that actually make it move and steer. It is all pretty sturdy designed, so that it can be durable and sustain some damage before breaking. Normally RC model cars have a lot of small parts that can be detached and replaced if needed, so essentially you can service your RC car in a similar fashion as big normal cars are being repaired. There are spare parts as well as tuning parts that may improve the capabilities or durability of the stock component, so ye, you can tune these as well and it does not need to be just performance tuning, it could as well be visual one.
Here are the three main components that are responsible for making your RC model car move (if it is electric one) - 1. steering servo, 2. electronic speed controller or ESC, 3. electric motor. These three components connect to the radio receiver that receives the commands from the user and based on the commands that come in they are instructed to do something such as increase speed or turn left or right. As already mentioned the control is fully proportional, meaning that there are no just two endpoints, but many points for the speed as well as for the steering, so you can achieve precise control.
There are a number of different servo machines that are used for steering the car left and right here, they are different in their features and implementations and as a result can provide varying speed and response time. The two most important ratings of a servo are the weight rating and response speed as they define how much it can move the wheels and how fast when there is a command to do so. Different RC models may require larger or smaller servos, with lower or higher weight rating and with faster or slower response time. The larger the RC model car is generally the larger the servo it needs that can provide torque and can respond faster. Some cars may need more torque while others may require faster response, but that can depend based on the purpose of the RC model car you are going for.
The ESC and the motor are responsible for how fast your RC car can go, they are specifically tied as depending on the motor requirements you need to find a speed controller that can provide the requirements. There are generally two types of electric motors: brushed and brushless, with brushless usually being faster and more powerful as well as more durable. Brushed motors are easier to control and are generally cheaper, but not as powerful and break down easier from overheating or from wearing down of the brushes. They are usually found in lower-end RC model cars while higher-end models do usually come with brushless motors and that is especially true for most racing models. Brushless models can be either sensorless or sensored with the latter being more precisely controlled, but also more expensive and requiring a more expensive controller as well to support the sensor functionality.
The battery of an electric RC model car is a very important component as it is responsible for the run time you get to play around driving the car. Depending on the scale of the RC car it could be a small NiMH or a larger and very powerful Lithium-Polymer battery. It is important to pair the RC car model with the properly required battery that can provide enough power required by the electronics, otherwise the car may not be able to achieve its maximum speed or it can drain the battery in just a couple of minutes instead of providing you a long fun driving time. The batteries also need to be handled carefully, especially the more powerful LiPo ones and that goes not only when they are used in the model, but after that as well charging and storing them according to some specific requirements to have them serve you long time and not give you trouble.
RC models use rechargeable batteries, because this way you can have a lot of fun time with just single battery that can last up to hundreds of recharge cycles if properly cared for. Of course it is always wise to have two or three batteries (or pair of batteries) that you charge before going out to drive the RC model, so that you will have more time to drive and will just replace the battery in the car when it gets discharged. Alternatively you can also carry a charger with you, so that you can charge batteries from a large car's battery or in a venue with power like an RC race track. Even in such cases it is still wise to have at least two batteries, so that you can drive with one while the other is charging. Batteries and chargers for RC model cars need more attention and they will be getting it later on.
Do note that you need batteries for your Electric RC car model as well as for the transmitter that you control it with, but even gas-powered RC car models will need batteries even though their source of energy for movement comes from burning fuel. Gas-powered RC cars still need batteries for the transmitter as well as for the servo used for steering the car and for another servo used to control the output of the gas-engine. More about gas-powered RC cars in the next part of the series...
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