Introduction:
Radio Control (RC) cars have come a long way. Beyond the WalMart and Radio Shack toys is another level whose technology is fairly amazing. Just looking at this photo you can see independent suspension, tie rods, king pins, Constant Velocity (CV) joints and shock absorbers with coil-over springs. But this is just the beginning.
There are two primary categories, Nitro (or gas powered) and Electric (Battery Powered). Sub categories to Nitro and Electric are off-road and on-road. Sub categories to road type are scale size. I prefer the Electric On-road 1/10th scale touring model. Primary components of an Electric 1/10th scale RC car are the Chassis, Body, Radio, Motor, Speed Control, Battery, and Battery Charger.
Chassis:
The chassis is the platform to which the Body, Radio Receiver, Receiver Antenna, Motor, Speed Control, and Battery are attached. As you can see, there is a lot of fascinating technology here. This is a picture of the Tamiya TL01 chassis. The chassis is a monoque design, meaning it is a strong hollow shell without internal strength reinforcement members. The stock chassis is made almost entirely of plastic with some steel parts such as screws and the drive shaft. The TL01 is a shaft driven Four Wheel Drive (4WD) with a ball bearing differential for each axle, four wheel independent suspension with Constant Velocity Drive (CVD) half-shafts, and shock absorbers. This is an excellent starter chassis with lots of upgrade or "HOPUP" options from Tamiya and other many other manufacturers. These improvements include exotic materials such as fiberglass, carbon fiber, aluminum, titanium, and Delrin. Improvements are aimed at reducing weight and increasing spped or increasing durability. However I found the basic plastic parts to be quite durable and lightweight.
You can obtain a Ready To Run (RTR) kit that includes everything you need to race for about $250.00 from online stores like Tower Hobbies. You can also buy the chassis (with a body) in kit form for about $100.00.
The kit requires you to put everything together including the tiny ball bearings in the differentials. No glue is used, everything uses screws.
Body:
There are lots of bodies available that range from scale models of sedans and sports cars to Formula I racers. Of course, I prefer the Nissan 350Z. The bodies are available separately or with chassis kits. The body comes in a preformed shell that must be painted, cut-out and stickered.
The sticker sets come with the body and are available separately. Some of the better kits come with pre-formed window masks that you apply prior to painting so the windows will remain clear after painting. The window stickers with the 350Z body are transparent smoke.
The bodies are cut from the form by a variety of means. You can purchase special scissors for this task. I have tried the special scissors, regular scissors, and tin snips. The best scissors for the job have thin and short blades. But I prefer to use a hot wire cutter and then sand the edges with a dremel.
The bodies are made from polycarbonate (Lexan) and require special paint. Ordinary plastic model paint is not to be used with these bodies. The paints are available in a wide variety of colors. To match my real 350Z, I paint mine with Pearl White followed by Sprint White. These bodies are painted from the inside, so pearl goes on first then the base white last.
Radio:
The radio consists of a transmitter, receiver, servo(s), and battery pack. The most common transmitter used for cars is the Pistol grip style where the trigger is the throttle and the wheel on the side is for steering. Most models have the ability to zero or null both the throttle and the steering. The Radios are available in either Amplitude Modulation (AM), Frequency Modulation (FM), or FM Pulse Code Modulation (PCM). Both the transmitter and receiver must be of the same kind. AM radios suffer from noise and control drift. FM radios have better noise performance and less control drift. PCM FM radios minimize noise and drift effects.
The receiver mounted in the car has an antenna wire that is fed through a small plastic tube that is attached to the chassis. The receiver has a crystal that must match the crystal in the transmitter. AM and FM crystals are different. The receiver also has connections for a battery pack and two servos.
The receiver battery pack provides power for the receiver and servos but is unnecessary if you use an Electronic Speed Control (ESC) that has Battery Elimination Circuitry (BEC).
Two servos are needed if you plan to use a mechanical speed control, otherwise just one for steering is required. The primary categories of servos include standard, high torque, miniature, and micro. Some have ball bearings other bushings. I use a ball-bearing high torque servo. The high torque uses more power but really helps for high speed hair-pin turns. The ball bearing gives longer life and better steering stability.
Motor:
The kit comes with a "stock" motor. While stock doesn't necessarily mean cheap, the one that comes with the kit is cheap. Although it will serve you well for getting started and you should use it until you learn how to control your car, you will undoubtedly want more performance. And there are lots of performance options in this area. The motor used on 1/10th scale electric cars is called a 540 size motor. Many different types of motors are available from many different manufacturers. The stock motor that comes in the kit has bushings instead of bearings, non-adjustable timing and non-replaceable brushes. Motors are rated primarily by the number of turns. Stock motors have 27 turns (27T) of 22 AWG copper wire on the armature. "Hotter" motors have less turns, such as 10 (10T), adjustable timing, ball bearings, stronger magnets, capacitors to minimize arcing, and replaceable/better brushes. As the number of turns decreases, so does the resistance thus drawing higher current. While the higher current produces more power, battery life per run is reduced. The same goes for better conductive brushes and stronger magnets. The idea is to increase current draw and higher power at the cost of run time. Although stronger magnets and better brushes can increase efficiency. Few motors have efficiency ratings. Some motors have double and triple windings. These are used primarily to spread power to the mid and high RPM ranges. I like the Trinity P2KPRO2 "stock" motor which is a stock replacement 27T fixed timing (24 degrees) motor. It has replaceable brushes and a copper end bell for better heat dissipation. I also use ball bearings to replace the bronze bushings. This motor has plenty of power for me and provides a decent efficiency and long run time. However, for "stock" racing rules, you would have to put the bushings back in.
Speed Control:
The kit comes with a mechanical speed control, which is really a three position switch operated by a servo, some of the RTR kits come with an optional Electronic Speed Control (ESC). ESCs are available from many manufacturers.
This is perhaps the first upgrade you should give to your car if it came with a mechanical speed control. An ESC with Battery Elimination Circuitry (BEC) will eliminate a servo for the throttle and a separate battery pack for the receiver. The BEC uses power from the car's main battery pack to power the receiver. The ESC also allows for proportional control of the throttle unlike the mechanical speed controls which are all or nothing. And some ESC's have a reverse or brake. But the elimination of a servo and separate battery pack for the receiver is well worth getting an ESC. Keep in mind that the ESC consumes a little bit of power itself. There are two primary ratings for an ESC, one is the number of turns motor it supports and the other is internal resistance. Other factors include pulse frequency, number of cell batteries it supports, and a reverse function or brake. The lower the internal resistance, the less power it consumes and the less heat it produces. The really low resistance models don't need a heatsink and are very small. This Futaba MC800C Professional ESC is my favorite. It has an internal resistance of only .00045 Ohms, supports 4-7 cell batteries, down to a 5 turn motor and has an optimal 3140 Hz pulse rate.
Battery:
The main battery pack used in the RC car provides power for the motor, ESC and receiver. Standard size is 6 cells although 7 cell batteries are available. If using 7 cell batteries, the motor and ESC must support it. I use 6 cell. The primary choice is Nickel Cadmium (NiCd) or Nickel Metal Hydride (NiMH). I prefer the NiMH. NiCd batteries typically have a rating of 1800 milliamphours (mAh) and have severe memory effects requiring total discharging prior to a recharge. The NiMH batteries have 3000 mAh and have greatly reduced memory effects eliminating the need to completely discharge the battery before recharge. The downside of NiMH batteries is that they are heat sensitive. The number of and speed of recharges for NiMH batteries must be reduced to avoid heat damage.
Battery Charger:
The battery charger you select depends on whether you are using NiMH or NiCd. NiMH batteries require special charging techniques for peak performance. This charger (DuraTrax Intellipeak AC/DC Digital Pulse Charger) handles both NiCd and NiMH. It peak charges batteries using two specialized peak charging technologies, plus discharging and cycling features not commonly found in other chargers. "Negative Delta V" peak detection for NiCds, plus advanced "Zero Delta V" peak detection technology specifically for NiMHs, providing full charges without overcharging. Built-in Artificial Intelligence to eliminate false peaks. Multi-function LCD, with selectable switch for viewing charge amps, charge voltage, or battery capacity in milliamps. Auto-selects peak detection method by identifying cell chemistry. Auto-identifies the quantity of cells being charged. Computerized control, 8-bit 4MHz CPU with 8K ROM, 1K RAM, 1-channel 16-bit analog-to-digital converter. High efficiency P-Channel MOSFET drive transistors. It has an 11-15V DC input and comes with DC clamps for connecting to your car battery for charging in the field. It has a small detachable, 12 volt 7 amp AC power supply with built-in cooling fan for charging at home. It can charge 4-7 cell batteries on DC and 4-8 cell batteries on AC. Infinitely Adjustable fast charge current from 0.5-6.5 amps. It has a pulsed fast charge, with 8-bit pulse width modulated current control output. 100mA trickle charge. Discharge voltage cutoff: 2.6volts 10 and 2 amp fixed discharge rates, selectable by switch. Fixed 2.6V discharge cutoff voltage. Not designed for discharging A or AA size (and smaller) cells. Cycle functions: Select a single discharge/charge cycle for periodic pack conditioning, or continuous "auto-repeat" cycles for reviving batteries that have developed a memory, or for breaking in a new pack. Four multi-function, high intensity LED indicators. Status light glows during charge and flashes when nearing peak. Audible mode select tone signals for easy set-up. Twin built-in miniature fans keep the charger cool, increasing efficiency and lifespan. Reverse polarity and overload protection. Designed to charge sub-C battery packs. And it comes with a one year warranty! The only problem I have with this charger is that the LCD resets to zero after it reaches 2000mAh. Other than that, I REALLY like this charger.
Ball Bearings:
This is the second upgrade you should give your car. These kits come with plastic bushings. But you can buy ball bearing sets that will replace every bushing with ball bearings. These lower friction and allow your car to run faster and longer per battery charge. There are several types available. Some that are sealed, some that you can clean and re-lubricate, some that are hardened steel, and some that are stainless steel.
Tires & Wheels:
There are so many different types of wheels and tires from so many different manufacturers to satisfy even the most discerning tastes.
Tires come in rubber and foam. The rubber tires come in a variety of different tread patterns including slicks. The wheels are almost always plastic although aluminum wheels are available for the off-road cars and come in a variety of patterns. The Tires are glued to the wheels with Super Glue as they are not inflated. Between the wheel rim and the rubber tire you can buy foam inserts that stiffen the tire and increase traction. The wheels bolt onto the model with a single lug nut. I like running the solid foam tires because they are more forgiving on the surfaces I race on.
Racing:
There are many clubs and sponsors for racing. The primary are NORRCA and ROAR. The rules for these events vary. Some events are stock only and others are anything goes. But I prefer just to meet on a weekend with friends in an abandoned parking lot, setup a course with soccer cones and have at it. Everything can and does happen. Regardless of who wins, it is an absolute blast.
It's a good thing there are a lot of parts available and spare bodies. You will crash, several times. We humorously refer to the gouges, scratches, and road burns on our cars as "racing stripes". The speeds these models attain are amazing and head on collisions with other cars or obstacles are ... very bad. Avoid head-ons at all costs. Although these models have "bumpers", there isn't much "bumping", more like smashing. One rule is to never reverse while racing or circle in the opposite direction.
It takes a little getting used to driving from a third person perspective. But you will get it after a couple outings. The primary disadvantage is depth perception. If possible, get up high and look down on the track. Standing on the side at eye level doesn't give a lot of perspective and depth perception, although this is how we normally race.
It's also handy to have two or three battery packs so that you can continue racing while a battery is charging. Put you charge all your batteries and service your vehicle the day before you are to go racing. However, since these models are plastic in nature, don't race when it is COLD. The breakage will be incredible.
Prior to racing, police the track and use a broom to sweep the area. Remember these are 1/10th scale cars. A small 1/4" pebble is like a 2.5" rock to a full size car. Even 1/8" chips are like 1.25" marbles. Also find a lot that is free of obstacles like light posts and concrete curbs or speed bumps. A 6" curb is like a 5 foot wall. And try to find one that is very level. A 1" groove/joint/dip is like a 10" ditch. These cars easily reach 20mph. So a 1/2" dip is like hitting a 5" drop at 200mph. All of this makes for a very interesting and unpredictable race. Unfortunately, it also makes for a lot of damage. I've performed some amazing, but unplanned, stunts due to small debris, irregularities and obstacles. This includes flipping over and going airborne. Now the TL01 has a fairly low Center of Gravity (CG), but when your power sliding through a turn and hit a little 1/4" hole in the pavement, your rim can catch and flip the car right over...and over and over. For display purposes, keep an extra body all duded up and get one for racing.
