In this article, we will look at the procedure for installing the radio system of an rc helicopter.

Before proceeding to install your radio system, you will need to do some tests to ensure that it will function properly in the rc heli. The range test should be performed according to your radio manufacturers instructions, but here is a general procedure.

1. Ensure that both the transmitter and receiver batteries are fully charged.
2. With only the battery and servos connected to the receiver, turn both the transmitter and receiver on.
3. Collapse the transmitter antenna .
4. Walk away from the receiver, while moving the transmitter sticks.
5. Continue walking until the servo movements become erratic.
6. Walk back towards the receiver, and stop when control returns to normal.
7. Compare this distance with the specified minimum range check distance in your owners manual.

If the distance you found is less than the specified distance in your manual, then the radio is not safe to use in your model and will have to be sent back to the manufacturer for repair.

Before mounting the servos in your rc helicopter, ensure that the throws are at 100%, and that the servo arms are set perpendicular to the servo body. Also, center all the trims and make sure that the batteries in both the receiver and transmitter are fully charged. This is important because all adjustments you will be making require the radio to be on. When you are about to attach the servos to the fuselage, disconnect the battery and servos from the receiver. It is important that only the rubber grommets supplied with your servos touch the rc helicopter body, and that the mounting screws are tight enough to compress the grommets. Do not tighten the screws too much, or the grommets can become too compressed to much to be effective shock absorbers. Once the servos are installed in the fuselage, reconnect the battery and receiver. After double checking that the all the trims are set to neutral and that the servo arms are mounted properly, you can proceed with installing the ball links onto the inner holes of all the servos.

The rc helicopter should come with pre-cut pushrods. Install these on the servo arms by either screwing on the ball links, or using snap on clevises. If you are using the snap on clevises, be sure to secure them by sliding on a piece of fuel tubing. This will prevent them from coming loose in flight. Once the aileron linkage is connected, move it with your hands to see if the swashplate moves freely, without friction. Install the other linkages in the same way, but be careful to match the throw of the throttle servo to the carburetors range of travel. If this is not done properly, it can cause overheating and damage the engine. Also, be sure that an idle position on the transmitter does not turn off the engine completely. There still needs to be a way to turn off the engine, but this can be accomplished with the throttle trim tabs on the transmitter.

The gyroscope should be installed as shown in the owners manual. Make sure to place it where it is unlikely to be damaged. Most rc helicopters will have a specified location for the gyro. Use servo mounting tape to attach the servo, this will insulate it against vibration and attach it firmly to the fuselage.

Mount the on/off switch on the side of the rc helicopter opposite the exhaust. Also, mount the switch in a place where it will be easy to access. Orient it in a logical way, so that you will not turn it off accidentally.

The receiver and battery are now ready to be mounted. Before proceeding, cover both with plastic wrap to protect against fuel, dirt, and other contaminates. Pack them with rubber foam, and secure them with rubber bands. Depending on the type of antenna your radio system has (wire or whip), the antenna will have to be either routed outside the helicopter, or left inside the canopy. Be sure to follow the instructions in your owners manual, and don’t wrap the antenna around itself. This will reduce it’s range and could lead to a crash.

In addition to using the tips above to help you install your radio system, always read the user manual of both your rc helicopter and your radio system.

If you have purchased an rc helicopter in kit form, you will then need to get a radio for it. The radio system is responsible for sending control signals to your rc helicopter. When you move the sticks on the transmitter the motion is converted to signals and sent out by the transmitter, picked up by the receiver, and relayed to the servos which control the flight of the rc helicopter. There are several types of radios available, and each has different benefits and costs.

A common question is whether or not an rc airplane radio can be used in with an rc helicopter. The answer is yes, but you will have less control options than you would when using an actual rc helicopter radio.

An rc helicopter radio is different from an airplane radio in several ways. The most important is the throttle for an rc airplane is used to control the engine speed, not the collective pitch. In an rc helicopter, both must be controlled. In order to use this kind of radio with an rc helicopter, both the engine throttle and collective pitch servos must be linked together via a Y harness. This will work, but you will have less control than if the pitch and throttle servos were independent of each other. Using this type of system works best in fixed pitch rc helicopters, because they do not use the collective pitch control in the first place.

When shopping for an rc helicopter radio, you will come across the term “channel” often. It has two different meanings, and each is important in your buying decision. It can mean either the number of servos the radio can control (which relates to the number of degrees of freedom the rc helicopter can have), or the specific frequency subset that the radio signal is sent on (the 72MHz frequency band is divided into channels numbered 11 to 90). A two channel radio can control two servos (for example the throttle and rudder servos). A three channel radio could have both throttle and rudder control, as well as elevator control. A rc helicopter will need at least 4 channels, and typically 5 or 6 channels. Some radios have many more channels, but these are not important to the beginner. The basic 5 channels control:

1. Aileron
2. Elevator
3. Throttle
4. Collective pitch
5. Rudder

The extra channel can be used to control gyro sensitivity or other functions. The cost of a radio system is highly dependent on the number of channels available. When buying your first rc helicopter radio, try to get one with at least 5 channels. More channels will enable you to use more advance features as you progress in the hobby.

Radio systems can also use different methods to transmit their signals. These can be FM, PCM, or PPM, or spread spectrum. The most basic is FM, or frequency modulation. This method is the same type used by FM radio stations, but on a different frequency. Many FM radios can operate simultaneously as long as they are on different frequencies or different channels on the same frequency. If two radios are operating on the same frequency and the same channel, interference will results and one or both of the models flying can crash.

PPM (or pulse proportional mode) radios are better than a normal FM radios because they can operate servos at a higher resolution. The radio transmits by first sending a timing pulse, and following this with the actual command information. The advantage of this system is that the receiver knows what to expect before the command arrives. A different timing pulse is sent for each control channel, and this cycle repeats many times per second. The rate at which these pulses occur is called the pulse rate of the radio. A greater pulse rate gives better control, but getting a high pulse rate radio is not so important for the beginner or casual flyer.

PCM (or pulse code modulation) is similar to PPM except that each pulse is coded. The rc helicopter will only respond to signals with this specific code. This means that it will cope better to interference. Although this technology is helpful, it does not make the rc helicopter immune to all interference. If another pilot turns on a radio using the same frequency and channel, the rc helicopter can still have its signals washed out by the other transmitter and crash.

A synthesized radio lets the pilot transmit on different frequencies. This is helpful when you are flying at a club where there are many other pilots, because you do not have to change the crystal in the transmitter and the receiver to change channels.

The most recent radio technology eliminates the need for channel frequency control, and is immune to almost all forms of interference. Spread spectrum radios can transmit and receive on multiple channels, at a frequency of 2.4 Ghz (2.4 billion cycles per second). This kind of radio automatically scans for two free channels when is is turned on. When it finds them, it uses both to transmit and receive. Spread spectrum technology is becoming more popular, and it will eventually replace the other three kinds of radios mentioned above.

Besides the type of radio, you will have to consider different types of servos to use in your rc helicopter. There are many different types, the broadest categories being: standard, coreless, and digital. Standard servos are the least expensive, but they also provide the least performance. Since the motors they use have coils wound on a rotating iron core placed between stationary magnets, they will not be able to start and stop as quickly as the coreless variety. These servos should really only be used to control the throttle of the rc helicopter. Coreless servos are the same, except that the motor inside them has coils that are rigid and rotate around a stationary magnet without requiring an iron core, and are able to accelerate more quickly. These servos typically have better resolution and more torque than their cored counterparts. Digital servos use a digital amplifier to achieve even better resolution and accuracy. Digital servos can be cored or coreless are better than non-digital servos for several reasons, including:

• More accuracy
• Faster control response
• Greater torque

These are the best type of servo, but they may not be in within the budget of the beginner. Whatever type of servo you choose, make sure that it has ball bearings supporting the output shaft. This will result in both smoother operation, and longer servo life.

Be aware that most radios come with only four servos, and you will have to buy a fifth yourself.

The last major radio component is the battery. The battery is used to power the various radio components. Most batteries are of the four cell variety, and supply 4.8 volts. This is sufficient for most models, but a 5 cell pack producing 6 volts can be useful. The more voltage you have available, the faster the servos will respond. For your first model, you should consult the instructions that came with it to determine what type of battery pack to use.

Several other radio features include, but are not limited to:

Tail rotor compensation:

Tail rotor compensation keeps the nose of the rc helicopter pointed in the same direction. This is accomplished via a gyroscope (which is explained in a previous article, ‘Introduction to RC Helicopter Gyros, Rate & Heading Hold’) telling the tail rotor how fast it needs to spin. When the pilot adjusts the pitch or throttle of the rc helicopter, the torque from the blades causes the nose to move in the opposite direction, and thrust from the tail rotor is required to counteract this.

Exponential:

Exponential allows the pilot to control how sensitive servos are. With this feature we can tell the servos how much to move for a given amount of stick movement on the transmitter. This can allow smoother control for small movements, and sharper control for large movements of the transmitter stick.

Gyro gain:

With this feature the pilot can control the sensitivity of the gyroscope on board the rc helicopter. This feature can allow for more stable flight, or easier aerobatics depending on the setting.

Electronic digital trim:

Trim can be used to correct undesired motions of a rc helicopter. It controls the adjustments of various servos during flight. For example, if I were flying a model with a slight left bank, I would slide the aileron trim lever in the opposite direction, to apply a right correction. These would cancel each other out, resulting in straight flight.

Programmable switches:

These are various extra switches located on the transmitter that enable the pilot to control special functions.

Multiple model configuration / switches:

This feature will let the transmitter control multiple models by storing the different settings for each. This is a good feature to have, because you can use one transmitter for several models, no matter how different they are. A memory feature will allow the transmitter to store this information.

Servo endpoint:

An adjustable servo endpoint will allow adjustments to the maximum throw of servos. This can be used as trim to compensate for undesired motions, by reducing the travel in the opposite direction.

Condition / flight mode:

This feature will allow different adjustments to flight parameters for different flight modes. This increases performance in all phases of flight, and is a very good feature to have.

When buying your radio, carefully consider all of the above features. If you’re unsure about your choice, you can ask more experienced pilots for help. If you take good care of your radio, it should last you many years.

In Part 1 of this tutorial, we looked at the different terms that you would encounter when shopping for rc helicopters. In Part 2 we will look at different points to consider when buying your first rc helicopter.

Should You Buy A New or Used RC Helicopter:

• Most new rc helicopters are sold in kit form, with the consumer assembling the product. This can be a problem for the novice, as kits can have several hundred parts.
• If buying used, ask to see the rc helicopter flown. It normally does not matter if the rc helicopter was ever crashed, as long as the broken parts have been replaced.
• If you are unsure about the condition of the rc helicopter, you can always ask another pilot to look at it with you.

Operating Costs of RC Helicopters:

• Visit your local hobby store and look at the various parts you will need. The cost of replacement parts is important.
• Find out what kind of fuel or batteries your rc helicopter uses. Costs vary depending upon the amount of nitro in the fuel or the number and capacity of lipo cells.
• If you plan to become a member of your local rc club, consider the membership costs.

Where to buy RC Helicopters:

Consider these points when choosing where to buy your rc helicopter.

Online:

• There are many online hobby stores. These stores usually have lower prices than conventional hobby stores due to the increased number of sales.
• Obtaining your rc helicopter at an online establishment usually means you can get your heli sooner, even if it is out of stock. A conventional hobby store can take weeks to restock a part you might need.
• When purchasing your helicopter on the web, it can be harder to find exactly what you need. Instead of being able to ask a store representative to help you find what you need in person, look for the availability of ‘live help’ or ‘live chat’ features .
• If you do purchase your helicopter online, make sure that the organization is respectable, and that they will stand behind their product.

Hobby store:

• At a hobby store, you can actually see and touch the items you are buying. This helps when comparing brands and to get a feel for the scale/size of the rc helicopters.
• Also, the dealer will most likely have several used models available. When the time comes to get a new rc helicopter, these can be a good deal.

Selecting an rc helicopter can be a daunting task, especially for the beginner. The first step is to know your options. To begin, we will examine the different types and configurations of rc helicopters available.

RC helicopter rotor blades can be fixed pitch, or collective pitch. An rc helicopter relies on the lift generated by it’s rotors. These rotors are comparable to the airfoil on the wing of an airplane. When the blades are locked at one angle, we refer to the rc heli as fixed pitch. This means that the blades always cut into the air at the same angle. This design has several advantages. The design is simpler, more durable, and easier and therefore cheaper to manufacture. The overall cost of a fixed pitch rc helicopter will be less than the cost of a comparable collective pitch model. The major disadvantage of the fixed pitch design is that the vertical component of flight becomes less controllable. Because the angle at which the blades cut through the air is constant, the only way to vary the amount of lift produced is to increase the rate at which the blades spin. This is accomplished by increasing the engine speed. The problem with this system is that because of inertia, the speed of the engine cannot be changed or controlled as rapidly as the servo you would use to control vertical thrust in a collective pitch rc helicopter.

In a collective pitch rc helicopter, the angle of the blades is changed to control the amount of upward thrust. Unlike a fixed pitch helicopter, when the command is given for the helicopter to climb or descend, the pitch of the rotor blades changes and the engine speed remains constant. The servo controlling the pitch of the blades (and the climb rate of the rc helicopter) only has to alter the position of the the rotors, which can be done rapidly with relatively little resistance. This is capable of a more rapid response than the engine having to accelerate the entire drive train and rotors up to a new speed. Clearly, the collective pitch design provides better control but at a higher price.

Cyclic pitch is the term applied to an rc helicopter which maneuvers by changing the pitch of each individual blade at different points along the path of rotation, causing them to generate more thrust on one side of the rc helicopter than the other. This will tilt the rc helicopter and result in horizontal motion.

An important option is known as auto rotation. In a fixed wing aircraft, if the engine were to stop, the plane becomes a glider with the wings still producing lift. The same can happen in an rc helicopter that is equipped with auto rotation. In an rc helicopter without auto rotation, the engine is connected to the rotors with out the ability to disengage - meaning that if the engine were to stop, the blades would do the same. This would result in the pilot losing control and the helicopter crashing. With auto rotation, the blades will spin freely during an engine failure. They will still generate some lift, allowing the pilot to maintain control and land. This is normally accomplished by a one way clutch or bearing. Auto rotation is a good feature to have because it may save your rc helicopter if the engine were to fail.

When manufactures refer to the size of a helicopter they are most likely talking about the displacement of the engine, rather than the size of the helicopter itself. Engine displacement commonly ranges from .30 to .90 cubic inches. Each size has it’s advantages and disadvantages, and these will be examined in depth in part two of this guide. For now though, the rule of thumb is that a larger engine is more powerful and will burn more fuel.

Pod and boom is a term applied to the type of helicopter where the body is composed of a ‘pod’ where the radio, engine, gears and other components are kept. The ‘boom’ is the part of the helicopter that holds the tail rotor. This is a common type of rc helicopter, accounting for the majority of the models available. This is different from the scale model style, where the entire model is designed to look just like the real thing. These generally have large fuselages which make them easier to see. They are also more aerodynamic. But for the beginner, pod and boom design is recommended, because of availability and durability.

Now that you are familiar with the different types of rc helicopters available, you are ready to make an informed choice on the type of model to buy. We will show you different points to consider when buying your first rc helicopter in the second part of this guide.

The gyro is an essential component in many rc helicopters. Gyros in rc helicopters are most commonly used to control unwanted movement on the yaw axis. When an rc helicopter rotates on its yaw axis, the direction the nose points (the heading) changes. The yaw gyro’s job is to sense any undesired rotation around the yaw axis (clockwise or counterclockwise rotation when viewed from above), and to automatically correct the orientation of the rc helicopter. Without a yaw gyro, even if the rc helicopter was trimmed out to fly straight initially, it would eventually begin to drift and rotate right or left. Normal maneuvering of the rc helicopter and external forces can result in undesired yaw rotation. When this occurs, the gyroscope senses this change in yaw and corrects it by controlling the thrust generated by the tail rotor to compensate for the rotation. This results in stable flight for the rc helicopter and no undesired changes in yaw.

Old rc helicopter gyros operated by using the inertia of a spinning weighted wheel. The wheel would resist changes in orientation, due to it’s angular momentum. A sensor would monitor the orientation of the spinning wheel and use it as a reference to compare to the rest of the rc helicopter. However, these gyros were heavy and consumed energy to keep the wheel spinning. As technology improved new rc helicopter gyros were developed. The solid state gyro has no moving parts, consumes less electricity than its mechanical counterpart, and is more crash resistant.

There are two important types of rc helicopter gyro. The rate gyro senses changes in yaw, and applies corrective action. When the motion stops, the gyro stops correcting. There are two disadvantages to this type: first, although this gyro stops the motion of the rc helicopter, it does not return it to it’s original heading. In other words, if a force were applied to an rc helicopter in level flight, it would turn and then the gyro would stop this motion. The end result would be that the rc helicopter has been turned to a new heading. A second disadvantage is that since the gyro only corrects after the motion has been detected, and the corrective action is always a little late.

The heading hold gyro operates in the same way as the rate gyro, with the exception being that after yaw movement has been corrected it returns the nose of the rc helicopter to it’s original position. This type of gyro does not stop giving commands to the tail rotor when motion stops, but will continue giving these commands to hold the nose of the rc helcopter in a certain orientation. Even more advanced gyros of this type will interpret the yaw requests that the pilot is sending through the radio control system, and will make whatever corrections are necessary to cause the rc helicopter to yaw at the desired rate. With this type of gyro, an rc helicopter will turn equally even in a crosswind.

Even though the heading hold gyro has many advantages, it places several demands on the rest of the rc helicopter system. It will require a very fast tail rotor servo, and a powerful battery to supply the servo, which will be required to make very fast corrections. This can strain the servo, and consume more power. The rc helicopter battery will need to supply the gyro and servos, so a higher capacity battery is better. However, the larger the battery, the larger the weight. An rc helicopter with a heading hold gyro and fast servos can use significantly more power than a less aggressive rc helicopter with a rate gyro.

Clearly, there are many choices of gyros for the rc helicopter pilot, each with it’s own advantages and disadvantages. When choosing a gyro system for your rc helicopter, be sure to consider battery capacity and weight, how you will be flying, and the type of servos with your radio system.

Flying your rc helicopter for the first time can be risky, especially if you have not had prior experience. Using a simulator is a good way to see what the hobby is all about and to practice without risking a crash.

There are many simulators available, both commercial products and free software. Any of them can provide a realistic way to try flying an rc helicopter. There are several benefits of using a flight simulator, the most important being you cannot damage a model while learning how to fly. Simulators can provide a good way to improve your flying skills. Many simulators support using your actual rc helicopter transmitter to control the simulated model, further enhancing the realism, while others require the use of a controller specifically designed to connect to your computer and simulate an rc transmitter. RC helicopter simulators will allow you to fly a variety of models, under different conditions. Most simulators will allow you to adjust various flight parameters. This means that you can simulate your own rc helicopter, and even simulate equipment failures. Unlike real flying, the simulator is not dependent on weather or time of day. Some simulators have training systems that will let you control different axis of motion, while the simulator controls the rest. This makes learning easy for the beginner.

Some available simulators include:

• The Dave Brown Products Ratio Control Flight Simulator 2001
• The Great Planes RealFlight R/C Flight Simulator G-3
• The Flying Model Simulator (FMS) - free!

There are many more simulators to be found online. Much of this software is upgradeable, and expansions can be either ordered, or found online. Flight simulators are a great way to learn to fly, without risking your expensive model.

Popular toy manufacturer WowWee has announced the Flytech Bladestar, a totally new type of rc helicopter which should become available this Feburary.

The BladeStar rc helicopter uses a single main blade along with small propellers mounted on the ends of two arms or ‘booms’. Sensors incorporated into the Flytech BladeStar allow it to fly autonomously and avoid bumping into walls or objects. In addion to this ‘auto pilot’ mode, it can also be controlled using its 3 channel digital IR remote to control (with beginner and expert level settings).

See a video of the BladeStar on YouTube.

The BladeStar rc helicopter recharges from the remote control and reports indicate that it will fly for 5 to 15 minutes and take about 20 minutes to charge. An optional combat feature which will allow you to shoot other BladeStar rc helicopters out of the air (or get shot out of the air yourself) had been mentioned. The Flytech BladeStar rc helicopter is suitable for indoor flight only, and is constructed from durable crash-resistant materials. Additional information is available on the official web site.

Interactive Toy Concepts has announced a remote controlled toy it is billing as the world’s smallest helicopter. It is a smaller version of their Micro Mosquito helicopter, called the Mosquito Micro Aerial Vehicle (MAV). The Mosquito MAV is an indoor RC helicopter measuring only 2.5 inches tall, 4 inches long, with a rotor diameter of 3.5 inches.

The Mosquito MAV features dual counter-rotating rotors geared to a single motor, with a vertical tail rotor for yaw control (steering), much like the Interactive Toy Concepts Black Ghost, but smaller. It has a twenty foot range, and is powered by an internal lithium polymer battery that lasts for 7 minutes. Recharging is said to only take five minutes, which would make it one of the fastest charge times on any rc helicopter. This Mosquito MAV helicopter will be available this year at most major retail and electronic stores for $49.99.

The Mosquito MAV combines the style of the Micro Mosquito with the design and precise flight control of the Black Ghost, all in the smallest helicopter design so far.