Radio-controlled car
From Wikipedia, the free encyclopedia
A radio-controlled car (R/C car) is a powered model car driven from a distance using a radio control system. Inputs from joysticks (or wheel and trigger) on a transmitter are sent to the car's onboard receiver. Radio-controlled cars can range from simple "stop and go" toys to competitive racing models, which feature all the complexity and adjustability of their full-size counterparts. Building, driving, and modifying radio-controlled car kits is a popular hobby.
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[edit] Types of cars
Radio-controlled (or R/C) cars are usually categorized as either "toy" or "hobby" grade. Remote-controlled vehicles differ from radio-controlled by the presence of a wire cable connecting the transmitter and the car, limiting their movement. This article focuses on the radio-controlled vehicle category, both toy and hobby grades.
Cars are powered by various sources. Electric cars are powered by small but powerful electric motors and rechargeable nickel-cadmium, nickel metal hydride, or lithium polymer cells. Most fuel-powered models use small internal combustion engines fueled by a special mixture of nitromethane, methanol, and oil (a blend of castor oil and synthetic oil), which are referred to as "nitro" cars. Recently, exceptionally large models have been introduced that are powered by small gasoline engines. Electric cars are generally considered easier for the novice to work with compared to fuel-driven models, but can be equally as complex at the higher budget and skill levels.
In both of these categories, both on-road and off-road vehicles are available. Off-road models, which are built with fully-functional off-road suspensions, can be used on various types of terrain. In comparison, on-road cars, which generally have a limited or non-existent suspension, are strictly limited to smooth, paved surfaces.
[edit] Toy radio control
The term "toy" or "toy-grade" in regards to radio control cars is used to describe vehicles of the pre-assembled type generally found in discount stores and consumer electronics stores. They are often colloquially referred to as "Radio Shack cars", RCcars, RCautomodelos, Automodelos de Radio Control. Some toy-grade R/C models may also be found in hobby shops in an attempt to appeal to young users. Generally speaking, a toy R/C is meant as a child's or adolescent's plaything. Though sometimes derided by users of more expensive and sophisticated hobby-grade equipment, toy R/C is an excellent way to teach a youngster basic vehicle control and to hopefully spark his/her interest in the hobby at a very reasonable price. Modern toy R/C vehicles are fast, fun and even rather flashy in comparison to hobby-grade vehicles. A toy R/C Lincoln Navigator brought to market in 2005 featured scale detail, full interior, chrome "dub" spinner rims, working show car lights, and even a fully programmable, built-in mp3 player used to emulate a high-powered stereo system. One of the largest R/C car models of any type is the 1/4-scale Cadillac Escalade from Columbia Telecommunications Group with its working FM radio. A Humvee less the broadcast receiver is built on the same chassis. Both are powered by a large, heavy 12-volt gel cell of the type often found in electric riding toys. A model of a Chrysler 300 SR/T from Planet Toys is a full 1/5 scale, twice the size of many hobby-grade R/C vehicles. Jada Toys has introduced 1/6-scale R/C cars influenced by full-scale vehicles featured in DUB City magazine. The "Shell Shocker" is a spherical, paddle-driven, all-terrain vehicle whose configuration can be changed by radio control. It was inspired by the Teenage Mutant Ninja Turtles franchise and is sold by Tyco R/C.
[edit] Disadvantages
There are disadvantages to toy R/C vehicles. First is a lack of spare parts. Toy R/C vehicles are meant to be played with until they fail. Stores selling the vehicles usually don't carry spare parts for the vehicles. Some basic parts may be available from the manufacturer - both Tyco R/C and New Bright have a basic parts list enclosed with their models - but they can be prohibitively expensive and parts may take several weeks to arrive from their Asian factories. Second, radio equipment, unlike hobby-grade, is non-standardized and non-repairable unless one has the necessary tools and equipment. Except for RadioShack's line of ZipZaps toy R/C cars and their XMODS line (which falls between toy- and hobby-grade), no aftermarket parts are available for toy R/C, although an enterprising modeler may be able to retrofit standard, discrete radio gear to a toy. Third, control response on some toy models comparable in size to hobby-grade vehicles is often slower than hobby grade, which actually makes those toys difficult to operate with smoothness and precision. An example is the aforementioned 1/4-scale Escalade and Humvee; they are promoted as having "semi-proportional" steering.
[edit] Hobby radio control
All hobby-grade radio-controlled cars require regular maintenance to ensure smooth and trouble-free operation. In comparison, cheaper "toy-grade" cars, found in discount and consumer electronics stores, are generally unserviceable. For those interested in mechanics, this maintenance provides an interesting adjunct to the hobby. Due to their modular construction, in the event that parts of a hobby-grade radio-control car breaks or wears out, they can be replaced individually. The availability of many replacement and high-performance parts for hobby-grade model vehicles allows them to be extensively upgraded (sometimes, to the extent of having no original parts remaining of the vehicle); in comparison, parts are generally impossible to find for toy-grade model cars, which are notoriously difficult to disassemble. In recognition of this distinction, Radio Shack released the popular XMODS and ZipZaps toy cars; these are mid-grade cars which can be tuned, modified, and repaired, although still to a lesser degree than hobby-grade vehicles.
In recent years, hobby-grade "ready-to-run" (or "RTR") models have become available from every major manufacturer of radio-controlled cars, attracting many hobbyists who would otherwise may have purchased a pre-assembled car. Vehicles of this type need little or no final assembly and in some cases, the bodies are shipped painted and trimmed, requiring little work from the owner before they can be used (other than purchasing and installing batteries). A number of cars and trucks are presently available only in ready-to-run form; recent examples include the Traxxas Revo and Hobby Products International (HPI) Savage 25, both fuel-powered model vehicles.
[edit] Electrically powered models
Electrically powered models usually stay cleaner during operation, are lighter in weight, and require less maintenance than fuel-powered models. After having run a few races with an electric car, the only dirt accumulated on the vehicle is usually from track dust. The light weight of electrically powered cars allows them to accelerate rapidly. Another advantage electric cars have against fuel-powered engines is that electric motors have a more even torque; in addition, they also have better throttle response. Electric batteries, however, take some time to charge; quick chargers can accomplish this in fifteen to thirty minutes while regular chargers take from one to four hours or even longer.
Routine maintenance usually consists of cleaning, inspecting the model car for damages, and replacing any parts that have been damaged or worn during use. The disadvantages of electric cars are they generally do not reach the same speeds produced by comparable fuel-powered vehicles unless expensive upgrades are added. High-performance electric motors must be allowed to cool down after use to avoid demagnetizing the permanent magnets. In terms of long-term maintenance of the motor, the application of motor cleaning solution is needed between runs to avoid wear from dirt and dust. Also, the bearings (or bushings) in the motor must be re-oiled periodically. Replacing the motor brushes is also sometimes required, and tires used must be very carefully selected to match the racing surface for maximum traction. Racing tires wear out relatively quickly, compared to "play tires", which are more durable but do not have quite as much traction.
[edit] Nitro-powered models
Fuel-powered engines allow model cars to reach impressive speeds unmodified. Maximum power is generally achieved at medium to high speeds, and a slightly slower throttle response than electrically powered vehicles is usually expected. This is because in an electric motor, the torque is instantaneous; in a nitro engine, as in a gasoline engine, it takes time for the engine to spool up and for the clutch to engage.
One disadvantage of fuel-powered engines is the dirt produced; a short five-minute run of such an engine is sufficient to coat the vehicle in dirt from fuel combustion. Cleaning is usually achieved by the use of compressed air blowers and solvents (such as denatured alcohol) because of the sticky nature of the exhaust residue and fuel that tends to cover the chassis. Tuning a fuel-powered vehicle requires some skill to maintain optimum performance, fuel economy, and to keep the engine from overheating, even in ready-to-run vehicles. Because of the higher performance and their ability to be driven for longer periods of time, mechanical wear to the vehicle is generally greater than in electric vehicles. In addition, the increased speed and weight of fuel-powered vehicles generally leads to collisions, causing greater damage to the collided vehicles, and some degree of safety concern needs to be considered when racing them.
[edit] Gas-powered models
There are few gasoline powered r/c cars available mainly because there isn't a huge demand for them. They cost much more (usually $800-$1000 rtr) than nitro and electric cars. They are also much bigger and therefore require much more space to run. They don't have high top end speeds (compared to nitro and some electrics) but have lots of power and don't take a lot of fuel to run.
[edit] Accessories
All r/c models generally require the purchase of additional accessories. For electrical vehicles, battery packs and a suitable charger are needed to power the car. A soldering iron and supplies are often necessary to build high performance battery packs and install upgraded electronics. For fuel-powered vehicles, a glow plug heater and fuel are needed to start the engine, as well as 4 AA size batteries, or a rechargeable 6volt 5 cell pack to power the onboard electronics. Hobby grade electric and fuel-powered vehicles almost always require 8 AA size batteries to power the transmitter.
There is also currently a growing industry of aftermarket manufacturers who produce upgrade or hop-up parts for hobby grade cars. Upgrades range from mere improvements to the longevity of RC car parts, to all out performance enhancements. through the manufacturer via mail or online. There are even a number of hobbyists who create their own upgrades for sale via classifieds, online forums (like RC Universe), or online auctions like ebay.
"Ready-to-run" cars can be purchased, which leave the factory in a pre-tuned condition that affords for good racing performance without prior adjustment. Alternatively, composite vehicles can be purchased that are either in kit form or are partially assembled, which are built and tuned by the owner prior to use. The Michaelus Galatsianos aka the "burn up" cars are some of the most rarest rc cars and are very hard to come by. They are only made in Greece however are quiet sort after.
[edit] Principles of operation
- See main article: Radio control
Radio-controlled cars, also known as RCcars or RCautomodelos, use a common set of components for their control and operation. All cars require a transmitter, which has the joysticks for control, or in pistol grip form, a trigger for throttle and a wheel for turning, and a receiver which sits inside the car. The receiver changes the radio signal broadcast from the transmitter into suitable electrical control signals for the other components of the control system. Most radio systems utilize amplitude modulation for the radio signal and encode the joystick locations with pulse width modulation. Upgraded radio systems are available that use the more robust frequency modulation and pulse code modulation. The radio is wired up to either electronic speed controls or servomechanisms (shortened to "servo" in common usage) which perform actions such as throttle control, braking, steering, and on some cars, engaging either forward or reverse gears. Electronic speed controls and servos are commanded by the receiver through pulse width modulation; pulse duration sets either the amount of current that an electronic speed control allows to flow into the electric motor or sets the angle of the servo. On the models the servo is attached to at least the steering mechanism; rotation of the servo is mechanically changed into a force which steers the wheels on the model, generally through adjustable turnbuckle linkages.
[edit] Electric models
Electrically powered models utilize mechanical or electronic speed control units to adjust the amount of power delivered to the electric motor. The power delivered is proportional to the amount of throttle called for by the transmitter - the more you pull the trigger, the faster it goes. Mechanical speed controllers use a network of resistors and switch between them by rotating a head with an electrode around a plate that has electrical contacts. Mechanical speed controllers are prone to being slow to react, waste energy in the form of heat from the resistors, and can become dirty and perform intermittently, and lack a dedicated braking ability. They are less expensive than high performance electronic speed controls and usually ship in low-end hobby-grade models. Electronic speed controllers use solid state components to regulate duty cycle, adjusting the power delivered to the electrical motor. In addition, most electronic speed controllers use the electric motor as a magnetic brake, offering better control of the model than is possible with a mechanical speed control.
Most electric cars up to recently used brushed motors but now many people are turning to brushless motors for their power and because they have no matienence. Most commonly they are not rated in turns but in a Kv number. The Kv number tells how much rpm the motor will have to each volt the esc puts through it. This is a much easier system of knowing the motor rpm unlike brushed motors where you have to run them though a dyno to know. Brushless motors are also used in bigger monster trucks and 1/8 buggies that have been converted to electric.
[edit] Fuel models
Fuel powered models utilize a servo for throttle and braking control; rotation of the servo in one direction will cause the throttle on the carburetor to open, providing more air and fuel mixture to the internal combustion engine. Rotation of the servo in the other direction causes torque to be applied to a piece which causes friction with the braking material. The brake is located on the driveshaft and stops only two wheels on a two-wheel drive car and all four wheels on a four-wheel drive car.
Fuel engine sizes most often range between .12-.21 cubic inches. This is due to restrictions by the main sanctioning bodies for radio-controlled racing. Many "outlaw" engines are manufactured larger than these, mainly intended for vehicles which will not be used in sanctioned races and therefore do not need to comply with these regulations. Engine size is related to the class of car; 1/10th scale on and off road vehicles usually are equipped with .12-.18 cubic inch engines, with 1/8th scale vehicles using .21-.28 cubic inch engines.
[edit] History
[edit] The beginnings of model racing
Small, nitromethane-powered engines originally entered the market in the 1940s. At the time, there was insufficient technology to control an engine-powered model car other than on a tether. "Tether cars", or "spin dizzies", were capable of speeds upwards of 70 mph (113 km/h), but merely ran in a circle from the tether. In the late 1960s, the first miniaturized solid state radio control systems became available, which allowed a model car to have servo-controlled steering, throttle, and brake functionality that could be remotely controlled from a radio-control transmitter unit. This allowed model cars to be able to run on a racetrack with the ability for precise control in a similar manner as with a full-sized vehicle.
[edit] First commercial products
In the mid-late 60s a British company, Mardave, based in Leicester, began to produce the first commercially viable RC Cars. Their first cars were nitro- or gas-powered cars sold in the local area in the early 70s.
In the early 70s several commercial products were created by small firms in the US. Most of these companies began as slot car companies and with the wane in popularity of that genre moved into the R/C field. Among these were Associated Electrics, Thorp, Dynamic, Taurus, Delta, and Scorpion. These early kits were 1/8 scale nitro-powered (then called gas) aluminum flat pan cars powered by a .21 or smaller engine. The bodies for these cars were made of polycarbonate (the most popular made of Lexan). The most popular engine was the K&B Veco McCoy. The primary sanctioning body for races for these cars was Radio Operated Automobile Racing (ROAR). In 1973-74, Jerobee, a company based in Washington State, created their 1/12 nitro car using a Cox .049 engine. Several aftermarket companies created parts for this car including clear Lexan bodies, heat sinks, and larger fuel tanks. This scale evolved into 1/12 scale electric racing when Associated Electrics created the RC12E in 1976-77. Jerobee became Jomac and created their own electric kit.
In 1976, the Japanese firm Tamiya, which was renowned for their intricately detailed plastic model kits, released a series of elegant and highly detailed, but mechanically simple electric on-road car models that were sold as "suitable for radio control". Although rather expensive to purchase, the kits and radio systems sold rapidly. Tamiya soon began to produce more purpose-built remote-controlled model cars, and were the first to release off-road buggies featuring real suspension systems. It was this progression toward the off-road class that brought about much of the hobby's popularity, as it meant radio-controlled cars were no longer restricted to bitumen and smooth surfaces, but could be driven virtually anywhere. The first true Tamiya off road vehicles were the Sand Scorcher and the Rough Rider, both released in 1979, and both based on realistic dune buggy designs. Tamiya continued to produce off road vehicles in increasing numbers, featuring working suspensions, more powerful motors, textured off-road rubber tires and various stylized "dune buggy" bodies. They also produced trucks, such as the Toyota HiLux Pickup, that featured realistic 3 speed gearboxes and leaf-spring suspension systems. All of these models were realistic, durable, easy to assemble, capable of being modified, and simple to repair. They were so popular that they could be credited with launching a boom in radio-controlled model cars in the early to mid 1980s, and provided the basis for today's radio-controlled car market. Popular Tamiya models included the Grasshopper and the Hornet dune buggies as well as the Blackfoot and Clodbuster monster truck models. The earliest Tamiya models, particularly the early off roaders, are now highly sought after by vintage R/C collectors and can fetch prices of up to US$3000 on internet auction sites if still in mint, unbuilt form. Acknowledging their continued popularity, several of the early kits have even been re-released by Tamiya during 2005/2006, with a few alterations.
A British firm, Schumacher Racing, was the first to develop a ball differential in 1980, which allowed nearly infinite tuning for various track conditions. At the time the majority of on-road cars had a solid axle, while off-road cars generally had a gear-type differential. Team Associated followed suit with the introduction of the RC10 off-road racing buggy in 1984 (see below).
[edit] Modern developments in radio controlled racing
In 1984, Associated Electrics, Inc. of Costa Mesa, California introduced the RC10 off-road electric racer; this model was a departure from Associated Electrics' regular line of nitromethane-powered on-road race cars. Designed as a high-grade radio controlled car, the chassis of the RC10 buggy was manufactured from anodised, aircraft-grade aluminium alloy. The shock absorbers were machined, oil-filled and completely tuneable; they were also produced from the same aluminium alloy. Suspension control arms were manufactured from high-impact nylon, as were the three-piece wheels.
Optional stainless steel miniature ball bearings were sometimes incorporated in RC10 wheels and transmissions. The RC10 transmission contained an innovative differential featuring hardened steel rings pressed against balls - which made it almost infinitely adjustable for any track condition. The RC10 quickly became the dominant model in electric off-road racing.
In 1986, Schumacher Racing Products released their CAT (Competition All Terrain) vehicle, widely considered the best four wheel drive off-road "buggy" racer of the time. The CAT went on to win the 1987 off-road world championship. This car is credited for sparking an interest in four wheel drive electric off-road racing.
Gil Losi Jr, whose family ran the "Ranch Pit Shop R/C" racetrack in Pomona, California, turned his college studies toward engineering, primarily in the field of injection molded plastics, leading to his foundation of Team Losi. When the JRX-2, the first Team Losi buggy, was released it initiated a rivalry with Team Associated that continues to this day. Team Losi went on to secure a number of achievements, which included the industry's first all-natural rubber tires, the first American-made four-wheel-drive racing buggy, and an entirely new class of cars, the 1/18-scale Mini-T off-road electrics.
Although Losi and Associated seemed to dominate much of the American market, Traxxas, (another American company), and Kyosho, (from Japan), were also making competitive two-wheel-drive off-road racing models. Although Losi and Associated were close rivals in the USA, Schumacher off-road models continued to be popular amongst European hobbyists.
Electric and nitro cars have come a long way in terms of power. Electric cars have gone from non-rebuildable brushed motors and ni-cad batteries to brushless motors and li-po batteries. Nitro cars have gone from small engines to huge .32 engines that are used in big monster trucks.
[edit] References
- RCNitroTalk.com. R/C Nitro Talk, reviews, news, and forums.. Retrieved on 02 December 2006.
- Savage-Central.com. Savage-Central Forums, News & more.. Retrieved on 30 September 2006.
- Learn More About R/C Cars. Team Losi. Retrieved on 23 September 2005.
- Cars & trucks. Easy RC. Retrieved on 23 September 2005.
[edit] See also
- Radio control
- Radio-controlled model
- Radio-controlled airplane
- Radio-controlled helicopter
- Radio-controlled boat
