Radio-controlled car
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A radio-controlled car is a powered model car driven from a distance using a radio control system. Inputs from joysticks 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 can be categorized in two ways, as either "toy" or "hobby" grade. Toy grade cars are electrically propelled while hobby grade cars use either electricity or fuel for power. Electric cars use small but powerful electric motors and rechargeable nickel-cadmium, nickel metal hydride, or lithium polymer cells to power them. Most fuel powered models use small internal combustion engines fuelled 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 than 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. There are often colloquially referred to as "Radio Shack cars". 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 being brought to market for the 2005 holiday season features 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 as well. First is a lack of available repair parts. Toy R/C vehicles are meant to be played with until they finally fail. Parts for such vehicles are not carried in the stores that sell them, unlike a hobby shop. 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. 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. 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 remote control car break or wear 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 whatsoever 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 professional hobby-grade vehicles.
In recent years, hobby-grade "ready to run" models have become available from every major manufacturer of remote control cars, attracting many hobbyists who would otherwise have purchased a pre-assembled toy car. Vehicles of this type need little or no final assembly and in some cases, the bodies are shipped painted and trimmed, requiring no further work from the owner before they can be used. 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 that electric cars has 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 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 engine, 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] Fuel-powered models
"Ready-to-run" fuel powered cars (commonly abbreviated to "RTR") 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.
Fuel-powered engines allow model cars to reach impressive speeds, with much higher top speeds than electric cars. 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 stubborn 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 electrics. 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] Accessories
Both fuel-powered and electric 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 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.
One example of this would be an aluminum aluminum gear that replaces a plastic gear to extend the service life of the part. Such parts are typically sold through local hobby retailers or directly 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.
[edit] Principles of operation
- See main article: Radio control
Radio-controlled cars use a common set of components for their control and operation. All cars require a transmitter, which has the joysticks for control, 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.
[edit] Electric models
Electrically powered models utilize either yes yes 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 on the transmitter. 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 resisters, 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.
[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. While this is most common, there are exceptions, notably conversion kits that wil allow a .21 size engine to be fitted to a 1/10th scale or a .46 size engine to be fitted to some 1/8th scales.
These fuel engines are ignited by a glow plug, a small spark plug type part that heats up instead of sparking. The small plug is heated by a glow ingnitor. Once the engine is running, the glow ingnitor is removed, and the vehicle is ready to be driven.
The overwhelming majority of fuel engines are 2-stroke piston engines, though some 4-stroke engines are commercially available for those who are mechanically inclined to attempt to fit them, with conversion kits available for a limited number of vehicles, however this has not gained much popularity for a few reasons. 4-stroke engines are generally more expensive than a comparable 2-stroke, mechanical complexity is increased making the need to regular maintenance more important, and 4-stroke engines must be larger to compensate for their lower power output for a given displacement. Still, there are benefits to a 4-stroke that has drawn some enthusiasts, namely a smaller and more quiet exhaust system and more consistent power with greater low-end torque.
[edit] Activities
[edit] Sanctioned racing
There are tracks and racing clubs around the world for enthusiasts to get together and race, and there are many levels of difficulty from novice all the way to professional, ensuring that there is a racing class regardless of skill or equipment level. R/C racing on a professional level is a serious motorsport, regardless of the size of the cars involved, with factory-backed drivers racing for cash prizes all over the world.
Some commonly raced classes and the types of models that race them are:
- 1/12 Electric Onroad - Rear wheel Drive Cam Am-bodied cars, Touring cars, oval racers
- 1/10 Electric Onroad - Touring cars, Can Am-bodied cars, Formula One/Indy cars, oval racers
- 1/10 Electric Offroad - 2WD trucks, 2WD buggies, 4WD buggies, dirt track oval racers
- 1/10 Nitro Onroad - Touring cars, Can Am-bodied cars, oval racers
- 1/10 Nitro Offroad - 2WD trucks, dirt track oval racers
- 1/8 Nitro Onroad - Touring cars, Can Am-bodied cars
- 1/8 Nitro Offroad - 4WD buggies, Truggies, Monster Trucks
It should be noted that the fractional number used throughout this article refers to the model's scale in proportion to its full-sized counterpart. Therefore, a 1/10-scale car is one-tenth the size of a real car, though most purpose-built racing models are not built to true scale.
Not all tracks will race all classes, as terrain, space and noise requirements differ from class to class. It also means that the same track cannot always be used for more than one or two similar classes.
However, if the class you drive in is not raced at your local track, yet is similar to a class that is raced, it is often possible to run with the other cars. This obviously must be discussed with the race coordinators prior to the race, and usually depends on the willingness of the coordinators to bend the rules in order to encourage new members to the track...and therefore to the hobby. In a race sanctioned by a governing body such as ROAR (Radio Operated Auto Racing) and IFMAR (International Federation of Model Auto Racing), the rules clearly define that only vehicles of the same class may be run together.
In the United States, the main sanctioning body for racing is ROAR. , itself a part of the worldwide IFMAR racing organization. At the ROAR level, there are thirteen different regions in the US and one region for all of Canada. Each region has a championship race, including the US Nationals. Placing well in the nationals will qualify a person for the Worlds Races, sanctioned by IFMAR. The IFMAR Worlds are the pinnacle of radio controlled competition. The governing body for the UK is the BRCA. .
The world's most successful driver is Japan's Masami Hirosaka. Hirosaka has won fourteen world titles in all electric racing categories except 1/10th touring.
[edit] RC Car Drifting
Another area of RC racing is Drifting. Cars use special low grip tyres and the car setup can be changed to allow the car to drift more easily. Car are not timed but are judged on the line, drift angle, speed and show factor.
[edit] Bashing
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RC Car Bashing is generally just using the cars for fun and not racing; "bashes" are organized through a network of friends, online through forums, wikis, or other types of websites. Sometimes bashes are organized at the neighborhood level in an impromptu fashion, near construction sites for example. The terrain of a construction site combined with the noise levels generated by the models (especially fuel powered models) lead people to congregate at the same location with their r/c models. During a bash enthusiasts are focused on having fun together instead of adhering to the strict rules and seriousness of racing.
[edit] World speed record
The 2003 Guinness Book of World Records lists the fastest-ever top speed of a radio-controlled car as 111 mph (178.63 km/h) set by Cliff Lett of Associated Electrics. Lett, a Team Associated professional driver and one of the designers and developers of the aforementioned RC10, set the record with a heavily modified Associated RC10L3 touring car at Irwindale Speedway on January 13, 2001. More can be found about the record at: Need For Speed
On July 30, 2006, at California Speedway in Fontana, California, Nic Case achieved a one-way radar-verified speed of 160.1 mph (257.7 km/h) using a modified Custom Works Intimidator chassis and Castle Creations HV-85 Brushless ESC, Neu 1509 2Y Brushless Motor and EVO 20 3300 8S2P Li-poly batteries.
[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 a racetrack, with the ability for precise control in a similar manner as with a full-sized vehicle.
[edit] First commercial products
In 1976, the Japanese firm Tamiya, who were renowned for their intricately detailed plastic model kits, released a series of elegant but somewhat mechanically crude car models that were sold as "suitable for radio control". Although rather expensive to purchase, the kits and radio systems sold rapidly; Tamiya eventually turned their attention away from scale detail of vehicles and towards the development of more purpose-built remote control model cars. Featuring working suspensions, more powerful motors, textured off-road rubber tires and often topped with stylized "dune buggy" bodies, these models were durable, easy to assemble, capable of being modified, and simple to repair. These models can be credited with launching a boom in the popularity of radio controlled model cars in the early to mid 1980s, and they 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.
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 RC-10 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 more professional radio controlled car, the chassis of the RC10 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 two-piece wheels.
Optional stainless steel miniature ball bearings were sometimes incorporated in RC10 wheels and transmissions. The RC10 transmission contained 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, following suit in 1990, 1994, 1995, and 1996. 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.
[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.
- offroad-cult. offroad-vehicles. Retrieved on 08 October 2006.
- Learn More About R/C Cars. Team Losi. Retrieved on 23 September 2005.
- Cars & trucks. Easy RC. Retrieved on 23 September 2005.
- Beginning RC. For absolute newcomers to the hobby. Retrieved on 14 May 2006.
[edit] See also
- Radio control
- Radio-controlled model
- Radio-controlled airplane
- Radio-controlled helicopter
- Radio-controlled boat
