When choosing your first RC helicopter you first have to decide which type of chopper you wish to purchase, a collective pitch machine, or a non-collective pitch machine.
If you are starting the R/C hobby from scratch and must buy everything, I would strongly suggest the collective pitch machine. Although it is a bit more expensive initially, it is by far the more versatile of the two and will help you enjoy more advanced stages of the hobby after you have learned to fly.
You will also find the learning process easier with a collective pitch machine.
On the other hand, if you are already into radio controlled airplanes and have a radio, and an aircraft engine in the range that would fit a non-collective machine, this route may be desired to drastically reduce the start-up cost and to get you involved in the sport with less money.
Once hooked however, you are bound to want to move up to a collective pitch machine. I am going to assume you are starting from scratch and will continue with the idea of starting with a collective pitch helicopter.
Unlike planes where there are specific trainer models geared solely for the first time kit, the differences between helicopters are more subtle with the major difference being size and precision.
The larger and more precision a machine is, the better it will fly. These machines would make great training helicopters but they are usually a lot more expensive, with high precision parts, and would be very costly to repair in the case of a crash.
They are better suited toward competition and the experienced modeler where accidents are usually minimal.
Keep in mind, when learning to fly a helicopter you are bound to have a crash or two and parts are going to have to be replaced. Replacing parts on a precision machine could really run you a bill! A good place to start would be a machine designed for a .30 size engine, a stableflyer with collective pitch, and one with a good availability of parts.
Now that you decided on what RC helicopter to get you will now need your field tools. There are many types of tools that you can purchase some you will use once but the following tools you will need the all the time.
Let's stake a lookat the field tools you'll need.
The Engine
The helicopter engine is similar to a 2-cycle aircraft glow engine except that it has a larger heat sink head for better cooling, and a carburetor with improved mid-range adjustment. When purchasing the helicopter engine, the muffler is not included.
Usually the muffler comes with the RC helicopter kit, but make sure to ask your hobby shop if it's included.
Different motors facilitate different starting methods. Some come with a pull start system for very simple starting. Others use a cone start where an electric starter is used in a manner similar to starting an aircraft. Still others use an electric starter and a belt for starting.
The Radio
A proper helicopter radio differs from a standard airplane radio. There are certain functions that must be mixed electronically and these are found only in radios designed for this purpose.
More and more often, one is able to find radio systems that have functions suitable to both plane and helicopters. If you think you may be involved in both aspects of the hobby, you may wish to choose one of these for your system.
Other things to think about when purchasing a helicopter system are the servos and the battery pack. It is desirable to choose servos that have output shafts that are ball bearing supported.
Since the pressure and vibration on the servos in a helicopter is usually greater than in a plane, bushing servos tend to wear out very quickly and lose their precision which is extremely important in the controlling of a helicopter.
Because you are using a minimum of five servos and a gyro (to be discussed later) in a helicopter, and the higher frequency of control input, it is very desirable to have a larger battery pack than the standard 600maH pack that comes with most aircraft radios. A pack in the range of 1000 to 1200 maH is a better pack to consider.
Many helicopter radios take both of these concerns into consideration and come packaged with five BB servos and a large batter pack.
Also, it is recommended to get a computerized radio so that it will be easier to setup your helicopter for the correct pitch and throttle settings. Non-computerized radios can also be used, but they tend to be limited in its function and you will very quickly outgrow them once you get into flying aerobatics.
Receiver
You will also need a receiver to receive the transmitter signal and then transmit it over to the servos. There are basically two types of receiver. But getting whichever depends greatly on your type of radio and what it can support.
PCM
The PCM receiver is a digital receiver that uses normal FM Frequency, but the signal is an encoded digital signal in which the PCM receiver interprets it as commands. Since the signal is digital, if there are any interference or the signal is poor, the PCM receiver can be programmed to go into a fail-safe mode. In this mode, the servos will move to a pre-programmed position until the signal comes back.
PPM
PPM receivers are the "standard" type of receiver for most radios. Glitches in signal are immediately noticed by erratic movements of the servos.
Some people prefer PPM toPCM due to the above reason, but in general, PCM receivers (and transmitters) are a lot more expensive than PPM.
Servos
Servos are mechanical motors which are linked to the receiver and to the helicopter's control surfaces via mechanical linkages. Again, there are many different kinds of servos ranging from3kg torque to as high as9kg torque.
Generally, the higher torque servos are used for advanced flying like aerobatics and 3D, and the normal or standard servos for general flying.
For a helicopter, you require a minimum of 5 servos.
1. Throttle
2. Collective Pitch
3. Tail Rotor
4. Cyclic Left/Right
5. Cyclic Forward/Backward
Gyro
A gyro is an electro-mechanical device used in a helicopter to help semi-automate the response of the tail rotor. In the case of an R/C chopper, the device fits electrically between the receiver and the servo that controls the pitch of the tail rotor blades.
A sensor measures any unwanted change in yaw of the aircraft and will correct the situation by increasing or decreasing the tail rotor pitch to stabilize the movement.
It is strongly recommended that a gyro be used in every helicopter. Without a gyro, the tail can spin around uncontrollably, making it spin and crash. Controlling an overly sensitive tail of a helicopter is most frustrating and the gyro can help make the flying much easier and more pleasurable.
Gyros are made by most radio manufacturers for operation compatible with their systems.
PiezioGyros vs. Mechanical Gyros
Generally, apiezio gyro is better than a standard mechanical gyro in the sense that it doesn't have any moving parts, and it's more sensitive to the movements of the heli. However, they are typically more expensive as well.
A new type ofpiezio gyro have recently hit the stores. Known as the heading lock gyro, this gyro is capable of maintaining the heading of theheli even in strong wind conditions and thus allowing you to fly in any direction without the head or tail swinging about.
Field Equipment
The field equipment you require will depend largely on the type of starting mechanism for your helicopter. If you have a glow motor with a recoil pull-starter, you will only require the basics of a fuel can & pump for carrying and pumping fuel to your heli, and a glow plug igniter to supply current to the glow plug during starting.
If you do not have a pull start, in addition you will undoubtedly need an electric starter powered by a 12 volt battery to turn the engine over. Making a flight box which contains all your necessary field equipment might be a good idea!
Other Accessories
Since the helicopter is purely a mechanical device, tools for assembly usually include items such as screw drivers, ball drivers, nut drivers, wrenches, pliers, fuel-filters, addition glow plugs etc. In addition to these there are a couple of specialty tools that come in handy when assembling and setting up the mechanics of your helicopter.
One tool you may want to consider to assist in assembly is a set of ball link pliers. The ball link is the most popular linkage piece on a helicopter and virtually all choppers use them. The ball link pliers greatly assist in the removing and adjusting of these links.
A second tool that is extremely valuable during set-up is the rotor blade pitch gauge. This device can help you line up your rotor blades so that your pitch is correct. A blade pitch gauge can go along way to helping avoid costly crashes and frustration down the road as so much of your chopper's well being depends on how well it is set up initially and maintained throughout its lifetime.
Of course, last but not least, glow engine fuel, which is normally a mixture of nitromethane, and lubricants like caster oil or synthetic oil. Helicopter fuels are normally 15% nitro, although you might like to use 20% for more power for aerobatic flight.
