Radio Control - Au Electronics

Everybody has driven a remote control car before, right? The first one you drove was probably something you can buy in the toy store for a few dollars. Not that there's anything wrong with that, but there's nothing to them. Load them up with landscape depleting batteries that will end up costing more than the car itself and drive. Done. Nothing to it is there?

This article aims to provide information and inspiration to those who prefer to drive "real r/c cars" per say. In all good honesty, I usually drive electronic cars. Nitro and gasoline are hardly my forte, and I don't pretend that they are.

While I have driven several nitro fueled cars, electricity is what I'm good at. So rather than the nitro cars every kid thinks is great until he drives a proper electronic car- this article will focus on what you need to know about choosing, driving, maintaining and racing hobby to competition grade r/c electric cars.

Before we get to far along in this, I would like to state that this is about what will help you. I would love to explain how potentiometers and the like work, but that's no good to you, is it?

So, assuming you don't currently own a car and would like to buy one; here's what you need to know.

-Cars are built of varying qualities. Generally, what you pay for is what you get. You pay for the size of the model and the materials used to build it- these range from molded plastic, to graphite, carbon fiber and anodized aluminum. Also remember that a more expensive part MAY not always be stronger. A graphite arm could be stronger than a carbon fiber arm, but the CF arm could be lighter. It can vary greatly.

-Cars can be bought in various states. The two most common are "RTR" (ready-to-run) or a kit. Ready to run does not always mean you have everything in the box you need- granted, some cars may have everything in the box, but fairly often "ready to run" kits will not supply batteries for the remote or a pack for the car and a charger. "Kit" usually implies that the car is assembled and comes without radio gear.

-Personally, I'd only ever buy a car that has a line of aftermarket upgrades or replacement parts. If you drive it with any kind of gusto- there will be breakages. It could be anything from stripping the spur to breaking an A-arm. It will happen, so check that parts are available!

-Cars come in different forms and sizes. The next page will demonstrate the pros and cons of each method.

Firstly, don't assume R/C cars are the size the manufacturers make them. Commercial cars range from anywhere from 1/64 to 1/4 scale- there may even be larger sizes available. A very common size for beginners is 1/10th scale. These cars are small enough to throw in the back of essentially any car, but large enough to drive anywhere (suitable..).

Larger scales will of course come with a greater cost not only in the starter model, but also in upkeep and repairs.

Next, the type. Every kid wants a monster truck, don't they? Oh well, I'll do my best.

(on road) Touring Car: Available in numerous scales. These tend to be smaller than monster trucks and stadium trucks of the same scale, and close to buggies. Most touring cars (exterior) are modeled on existing sedans. However, under the shell is a whole different story. Nearly all utilize 4 wheel drive, either through a belt or shaft. Extensive effort has also been put into keeping a low center of gravity and a balanced chassis.

(off road) Monster truck: Every little boys dream, their very own monster truck! These are usually the largest type of a given scale, and often the slowest (for the same powerplant). However, this disadvantage is compensated by above average clearance, torque, size and weight. You wont see a sedan running of a monster truck anytime soon, will you? Normally 4WD

(off road/mix) Stadium truck: For those who are torn between the well, monstrous monster truck and the nimble buggy. Often described as having quicker acceleration, speed and more handling response than a monster truck, though this of course comes with the downside of less clearance, less torque and less durability. Available in 2WD and 4WD.

(off road) Buggy: Lighter and nimbler than a truck or monster, buggies will give more acceleration, speed and handling than anything else that goes off road. But it's also easier to hit things, seen as your dragging closer and closer to the ground. And when you do, it may not always be a bounce off. Being lighter, buggies are often substantially weaker than trucks or monsters. Available in 2WD and 4WD. Buggies are also smaller than trucks and monsters.

Niche models:

Not everybody wants what everyone is driving. Some may want something else. Forgive me for what I miss here, but there really is a lot to get through.

-Oval/stock models: On road, two wheel drive speed demons. As the name implies, these are driven in wonky circles until the driver is bored, or you crash. There isn't much to say for handling as you're just driving around in circles, and frankly the one millimeter of latex between you and what you hit is probably the most resistant part of your car. Still, it's out there if that's how you're inclined.

-Rock crawlers: Heavily modified monster trucks, sporting increased travel, lower gearing, monstrous torque, locked diffs and a whole bucketload of other things to help you climb up rocks. Commercial crawlers are available, but to be honest the best is the one you rip apart that txt or clod to build. Before you consider this, they are slow! Tops, you'll get around 5 km/h. This comes with the reassurance that the only thing that will stop you is rolling over.

-Short course: Relatively newer offerings from companies such as traxxas and associated. Similar to the stadium truck, but more scale-esque. Not much different from the stadium truck, and I've never driven one so I can hardly judge.

If you went out and bought a RTR model, good on you. If you took the hard path with a kit, read on.

Depending on the kit you will usually need a motor, an esc, batteries and radio gear.

1) The battery:

First of all check the model of speed controller you are using. It will run on a certain voltage, having an upper and lower limit. Before you choose a capacity and voltage, you need to consider what type of battery you want. Essentially, there are four to choose from. Ni-Cd (nickel cadmium), Ni-Mh (Nickel metal Hydride), Li-ion (lithium ion) and Li-Poly (lithium polymer). These require certain chargers, otherwise the battery may be damaged! Some types of chargers may multitask; eg. charge Ni-MH and Ni-CD. Lithium chargers are more expensive, but can often improve the performance of your car and pay off in the long run.

Notes:
-Discharge Ni-Cd batteries pre-storage.
-Do not completely run down Ni-Mh cells, only run to dump. This is when the cars performance drops very noticeably.
-Do not overcharge or discharge lithium cells too deeply.
-If a lithium cell has been bent, deformed etc. DO NOT CHARGE IT! IT CAN AND WILL EXPLODE!!

2) The ESC

Here are the choices in esc:

-Brushed only *Programmable.
*Automatic
-Brushless *Sensored
*Unsensored

Brushless ESC's will usually also run brushed motors, it will be noted on the packaging. Electronic speed control's run on different voltages, meaning this should be taken into account when selecting a battery.

Brushed ESC's will not run brushless motors. Also, ESC's have a limit. This is the lowest wind or the highest KV. (KV= rev's per volt) (the lower the wind, the higher the RPM). Exceeding this can often damage the speed controller.

Unsensored ESC's will not run sensored motors, but sensored esc's will run sensorless motors. Generally, a sensored motor will have more power.

Charger:

This should be purchased at the same time as your battery. Asides from the obvious things, such as suitability for your kind of pack I'd recommend these features.

-Has an option for AC power or to run on DC (ala, your car?)
-Is a peak detection model
-Will charge a broad range of voltages
-Can multitask
-Of a good quality- use your judgment here. It'll pay off when you're going through packs slower (long term)

Motor:

First of alls, you have two main options. Brushless or brushed. Brushless motors branch into sensored and unsensored, while brushed motors are generally similar (things such as V brushes, et cetera are available.

If you have the money, go brushless. You get more speed, torque, reliability and there's stuff all maintenance to do. Just oil the bearings, keep it clean and make sure it's all running smoothly and it will serve you for a long time.

On the other hand, you have brushed. These are often slower, less reliable and more costly to keep running, but have a cheaper up start. As they have brushes, you will to replace them or re cut them regularly with a brush file/cutter. The commutator will also need maintenance. Keep the endbell free of debris..oil the bearings and your away.

If you want a personal opinion on motors, go brushless. In my T4 alone I've used 4-5 brushed motors, them all ending in catastrophic failure due to the abuse they are subjected to. The one brushless setup I have in it I've had for the length of easily 2 brushed motors with no issues, except for some damage to a wire. I'm sure it will serve me for a long time to come.

Something worth noting is that brushless motors often run cooler and are more efficient.

Brushed motors are rated in winds, which is the number of winds of wire wrapped on each pole of the shaft. Brushless motors can be rated in KV or winds. KV is given in an RPM, then you time that by your voltage used for the final RPM.

I should probably mention something about timing here, but I wont. It's been so long since I've used a brushed motor that I can't remember which way advances and which way retards timing. And yes, retards is the correct word my window licking, short bus riding friends.

Again, if you went the long road with a kit you'll need to pick up radio gear. This refers to a transmitter, receiver, servos and occasionally a fail safe.

I cannot personally suggest a particular piece of radio equipment, as I've used so little of it. I've literally had no problems with my JR setup. It is a basic one, but it gets the job done. Things to watch out for/consider:

-Channels are the number of functions transmittable. If you just want forwards/backwards, left and right then a 2 channel is fine.
-The receiver must use the same band crystal as the transmitter
-Try to stay away from the 27 MhZ band, It's so common, especially with children toys. You don't want a toddler running off with your pride and joy.
-Try to get a transmitter that boasts an impressive range.
-A rechargeable battery pack in the transmitter is nice, trust me it will save a lot of money on AA's.

You'll need a servo to control steering. If you're stuck in the 50's your car may use a mechanical ESC which uses a servo (I actually have a tamiya with a setup like this). If you're using an offroad car, save yourself the trouble and buy a servo with a lot of torque and metal gears. If you're an onroad person, you may be able to skimp buy with plastic but metal will give you die-hard reliability.

If you have money to spend on good gear, consider the 2.4GhZ spektrum equipment. The reliability and convenience greatly exceed anything else available.

A fail safe is a great investment. It monitors radio signals and in the case of a battery or something running out locks down the car. Mine has saved me more than once, but if you race near forgiving things then don't worry with it.

You may be content with the tires and suspension you get given with it. Personally, I wasn't. Tires become useless after they've been balded and had holes torn in them..And depending on quality you might want more dampening.

Before you go replacing suspension, consider upgrading. If they have threaded bodies and don't leak, then it's easy enough to just change the springs and shock oil. These items should be available in most good hobby stores. The manual should have information on rebuilding shocks.

When it comes time to replace your tires (unless your a 20 turn stocker man) check that the rims you get match the drive output of your car (hex or pin?). Tires should be fitted to the rims, and glued with a bead of cyano (super) glue.

Solid blocks will last longer than pins, but usually give you less traction on hard-packed surfaces. The trade off is up to you. I use a pair of blocky road tires for general use, a pair of treads from 1/10 thunder tiger MT for speed runs/heavy duty stuff and a nice pair of crimfighters for racing. Up front I run (I use 2WD) ribbed tires or the same as the back/

Eventually, once you are getting bored of your car the thirst for aftermarket parts may become available. A word of caution, they may do stuff all. After upgrading my T4 to 80 or 90% FT parts you only notice the difference on a good, clean track with smooth crimefighters. Elsewhere, the difference isn't really that noticeable.

Also remember that you may lose some weight by going after market, but you will pay out good money that could be spent on motors, esc's etc.. Often aftermarket parts can make the car weaker, or in the case of aluminum hop-ups they may transfer the stress elsewhere on the vehicle. This could lead to more expensive, harder to fix breakages.

For the sake of people, I will use proper English here.

Q: But aren't nitro cars faster?
A: They can be, but no. The world record is held by an electronic car. For spending similar amounts of money, electronic cars can be faster.

Q: What is a normal startup cost?
A: Well this obviously depends what you want to buy. Decent (cheaper) batteries can run at 40 dollars each (AUD), with chargers being around 100. Then several hundred dollars for the vehicle. You could end up with a fairly respectable car for under $500.

Q: Do the gears I use affect my car?
A: Yes. Lower gearing will give more torque and less speed, while higher gearing gives the opposite. Overgearing can cause your motor undue strain while undergearing can cause power wastage.

This will be added to as questions are asked.

Simple enough.

Manufacturers:
http://www.losi.com/ Losi
http://www.rc10.com/ Associated
http://www.teamtrinity.com/ Trinity
http://www.traxxas.com/ Traxxas

To be continued