RC cars are classified by the scale, type and power plant types. These three classifications will be explained briefly along with some other components that are common in all RC cars. 1. Scale: RC cars are built in different sizes and shapes. In the RC world, scale is the word to use for size. One quick way to determine the size of the vehicle is to look at the number after the 1. As the number after the 1 decreases, the bigger the RC car is, and vice versa. For example, a 1/5 scale RC car is larger than a 1/18 scale RC buggy. A 1/5 scale car is one fifth the size of a real car. 1/10 scale is the most popular especially in drift cars. 2. Cars Types: A. On-Road car: On-Road car is low slung with very little ground clearance. They are designed to race on asphalt or concrete, or a smooth indoor floor surface, and cannot handle uneven terrain. Their suspension is stiff with little travel, but theyll drift around corners like nobodys business. B. Rally car: Just as with real cars, RC rally cars bridge the gap between on-road race cars and off-road trucks. These cars dont have the ground clearance for really rough terrain, but with the proper tires theyll do well on either paved or dirt tracks. C. Monster Trucks (MT): Huge tires and lifted suspension. They usually arent the fastest, which is actually good because they dont handle well at high speed. However, excellent ground clearance means theyll run over pretty much anything. D. Buggy: Open wheeled with a narrow front, usually an exposed motor in back and a wing on top. Buggies have relatively low ground clearnace compared to Stadium Trucks (ST) and are preferred for dirt-track racing rather than going through grass and brush. Buggies are the fastest RC off-road cars. E. Stadium Truck (ST): Basically a buggy with a modified truck body and modified (usually higher) suspension. STs are sometimes referred to as truggies, though there are technically some minor distinctions between the two. A good all-around truck that will handle well on pavement, dirt and gravel, but can still get over grass without too much difficulty. F. Short Course Truck (SC): Usually a bit narrower than STs or buggies and the outer body is widened to cover the wheels. They usually have smaller wheels and a bit less suspension travel and ground clearance than STs. SC look more realistic and they are newest off road type. Good for pavement and dirt, but the lower body gives them some trouble with coarse gravel or high grass. G. Rock Crawler: These are a specialized version of MT with highly articulated suspension components. They go very slow, but theyll climb over obstacles that nothing else can handle. 3. Power plant RC cars can be electric, nitro or gasoline powered. The electric RC is powered by a motor that requires electricity (in the form of a battery pack) as the fuel. The nitro RC uses an engine fueled by a methanol-based fuel that contains nitromethane. This nitro engine and nitro fuel are the RC equivalent of the gasoline engine and gasoline used in your full-size car or truck. Another class of hobby-grade RCs have gas-powered engines that use gasoline rather than nitro fuel. A. Electric powered: Electric RC car are powered by either a brushed or brushless (BL) motor, with a matching Electronic Speed Control (ESC) The brushed electric motor is generally the only kind of motor found in toy-grade and beginner hobby-grade RCs. Kits and other hobby-grade RCs still commonly used brushed motors although brushless is becoming more readily available. Small contact brushes inside the motor transfer current to windings in the rotor which cause the motor to spin. Brushed motors come in fixed and nonfixed versions. Electric motors with fixed brushes are nonadjustable and cant be modified or tuned. Nonfixed brushed motors have replaceable brushes and the motor can be modified and tuned to a certain degree as well as being cleaned of dust and debris that accumulates during frequent use.Brushed motors are rated by the number of turns (t) they use. In general, lower turns means higher speed. Most stock motors are in the 19t-30t range while high performance motors will be 5t-12t. Brushed motors have two power wires. Rebuildable brushed motors are made to easily be disassembled so that the brushes and springs can be replaced when worn out. Most cars come with non-rebuildable motors (often called cans) which are sealed and must be replaced when they wear down. Becoming increasingly popular in the RC hobby, brushless electric motors are still slightly high-priced compared to brushed motors. The appeal of brushless motors is the sheer power they can give to your electric RC. Brushless motors, as the name implies, do not have contact brushes, dont require frequent cleaning, and because there are no brushes there is less friction and less heat -- the number one killer in motor performance. Brushless motors can also handle a lot higher voltage than brushed motors. With a high voltage supply brushless motors can help a beginner RC race at blistering speeds. BL motors are faster and more efficient, which means theyll run longer on a single battery charge. BL motors are significantly more expensive than brushed motors. BL motors are rated by the number of turns(t), another rating for the BL motors is KV which is the rpm/volt (accuracy within +/- 3% for most motors). The higher number of turns (t) the lower KV rating and the slower the motor is. Note that faster is not always better, since heavy vehicles actually do better with lower KV rated motors, which dont spin as fast, but have more torque. All BL motors have three power wires. Brushless motors are available as either sensored or sensorless. Sensored motors have additional wires which plug into the ESC. These wires connect to sensors inside the motor and allow the ESC to know exactly what the motor is doing for better control. Sensorless motors are cheaper, but they are not as smooth running as sensored, especially at low speeds. Many sensored ESCs will also run sensorless, but not the other way around. ESCs are the electronic devices that control how fast the motor runs - basically a digital throttle. Without getting into too much unnecessary detail, just be aware that a brushed motor requires a brushed ESC and a BL motor requires a BL ESC. Most BL ESCs have extra programmable features, like anti-lock breaking, low-voltage cutoff and signal loss protection. Brushed ESCs are rated by the number of turns (t) they support, while BL ESCs are rated by amps (A). B. Nitro engines are 2-stroke, air cooled internal combustion engines. Nitro engines have carburetors, air filters, flywheels, clutches, pistons, glow plugs (similiar to spark plugs) and crank-shafts just like full-size gasoline-powered cars and trucks do. There is also a fuel system that includes a fuel tank and exhaust. The head heatsink is the main part on a nitro or gas engine that dissipates the heat from the engine block. The full-size auto equivalent is the radiator and water pump that circulate coolant through the engine block to keep it from overheating. On nitro engines there are ways of regulating the temperature by means of tuning the carburetor to lessen or increase the amount of fuel that it mixes in combination with air (leaning or richening). The ability to disperse heat through regulating the fuel/air mixture thus controlling the engine temperature is one of the few advantages that nitro or small scale gas engines have over electric motors. Other components of RC Car Servo The servo is the device that actuates the steering for your car in both electric and nitro powered cars. Also it controls the air flow into the carburetor to control speed of nitro powered cars. It gets a signal from your receiver and moves its arm accordingly. Servos are rated for torque (kg.cm) and speed (sec. per 60 degrees). Unless you make some major modifications to your vehicle, you should be fine with the stock servo or a replacement which is similarly rated. Transmitters and Receivers The transmitter (Tx) is the radio that you use to control your radio control vehicle. The receiver (Rx) is the little box with the antenna sticking out of it takes your radio signals and translates them into signals that the ESC and/or servos can understand. There are three main types of Tx/Rx systems, and the two components must be of the same type to work together. The older systems are AM and FM. Both AM and FM setups are made to work on one of several frequencies, and each of those frequencies are broken down into a handful of channels. Most AM and FM sets use removable crystals to determine the channel they work on. If you are using your vehicle near other RC cars, it is important that no two cars use the same channel, or you will interfere with each other. The third, newest, and by far the best system is Digital Spread Spectrum (DSS). These sets work on the 2.4GHz band, so many people refer to them by that number. A DSS Tx must be bound to a Rx, which syncs them to each other. Once bound, the Tx and Rx will communicate without noticeable interference, no matter how many other RC vehicles are near by or what type of system they use. Every Tx is rated based on the number of channels (control channels, not to be confused with the frequency channels) it supports. Most cars only need two, one for the throttle and one for steering. Batteries There are two types of batteries currently used for RC cars - nickle metal hydride (NiMH), Nickle Cadmium (NiCad) and lithium polymer (LiPo). All batteries have two key ratings which you should be aware of: Voltage (V) and milliamp-hours (mAh). Voltage can be thought of as electrical pressure. The higher the voltage, the stronger the battery is. The mAh rating tells you the capacity of the battery. The higher the rating, the longer the battery can run between recharges. NiMH batteries are sold in packs consisting of 6 or more cells. Each cell provides 1.2V, so a 6 cell pack would be rated for 7.2V. NiMH batteries are heavier and cannot provide as much current as LiPo, but they are cheaper and needs less attention using them. NiMH batteries are generally recommended for beginners. LiPo batteries consist of packs containing two or more cells of 3.7V each. A two cell battery has a total voltage of 7.4V, and is usually called a 2s pack, which stands for 2 cells in series. LiPo batteries have another rating in addition to voltage and mAh: C. The C rating is an indication of how much amperage a battery can supply or (discharge rate). In order to know the maximum amperage that the battery can supply multiply the C rating by the battery capacity. Ex. A 4000 mAh 2S LiPo with 30C, maximum amp is 4000x30= 120000mA = 120 Amperes. LiPos are much lighter than NiMH, and they are able to provide more current as well. The down side is that they can be more expensive, and they require more careful handling. You must use a special LiPo charger to recharge them. LiPo batteries are very sensitive, and all the cells must be charged to the same level or you will have problems. All LiPo batteries have a 2nd, smaller connector called a balancing connector so that the charger can monitor and charge the cells individually. If you discharge the batteries too far (below 3V per cell), they will be damaged and cease to function properly. If you overcharge them (above 4.2V per cell), short them out, or physically damage them, they can explode. Sources amain rcuniverse rcvehicles.about
Posted on: Thu, 07 Aug 2014 22:57:48 +0000
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