BEGINNERS - HELICOPTER
Radio Gear

As your radio control system is the only link between you and your model (and therefore the only means of preventing it from crashing!), you should give this decision the consideration it deserves.

There are several main manufacturers of Radio Control Gear (RC Gear) whose equipment is readily available in the UK. In this technological age, the reliability of modern RC Gear is impressive. It is rare to suffer a radio failure where the actual equipment is at fault.

The Achilles heal with the use of RC Gear originates from Interference caused by other users, transmitting on the same frequency. In a well organised club, there should be a suitable Frequency Control system in operation at all times. We cannot sufficiently stress the importance of this matter and would urge you to view our “Frequency Control” section for further information.

In the UK, RC Gear specifically designed for RC flight will operate on the 35MHz band. This is due to the fact that within the UK, the 35MHz band is solely for model aircraft. Equipment on the 27MHz band is also legal for model flying, however as this band is also legally shared with model boats, model cars, CB operators etc, there is a higher risk of interference. Additionally, there are no RC systems available in the UK on 27MHz that can provide the necessary functions and channel mixing that a helicopter requires. As such you should only consider using a 35MHz system, specifically designed for flying model helicopters.

When using RC Gear a significant number of failures can be attributed to the batteries that power the transmitter and receiver. Should either one of these batteries become unable to power their respective functions, due to lack of charge or cell failure, then you will no longer be able to control your model. Exactly where your model will come down (effectively crash) in this situation, is very much a case of luck. It is therefore vital that your transmitter and receiver batteries are sufficiently charged and preferably monitored before each flight. The installation of the radio gear inside the model must also be to the highest standard to ensure reliability. Directions on fitting the radio gear will be given in your instruction manual however further advice is readily available from your fellow club mates or local model shop.

Generally, your RC system will be supplied with a transmitter, receiver, 4 servos, rechargeable batteries and a suitable charger.

Picture of typical Helicopter Radio Control system

When all have been connected and switched on, and when you move the transmitters stick, a signal is sent to the receiver which in turn moves the servo connected to that channel, to the travel (distance) requested by your finger on the transmitter stick. The movement is proportional, i.e. the further you move the stick, the further the servo’s arm travels. Each servo arm is connected by a pushrod to a specific control on the helicopter and operates that control as a real pilot would in a full size helicopter. You could therefore think of the servos as the full size pilots limbs!

On a helicopter the servos are generally under increased load, as virtually all controls are being moved simultaneously. As such there is a greater drain on the receiver battery that powers them. It is therefore advisable to fit a receiver battery that has an increased capacity to cope with these loads. This may mean that you have to purchase a different battery to that supplied with your RC system. As a rule of thumb, a 1200mAh battery would be the minimum required in a “30 size” helicopter. This would increase to 2000mAh for a “50 size” helicopter upwards.

Another electronic device required for a helicopter is a Gyro. A Gyro is designed to stabilise the tail rotor control by detecting adverse movement of the tail rotor and automatically applying an opposing movement to counteract it. The Gyro also recognises movements requested by the pilot and does not oppose these.

Picture of a typical modern gyro.

As with the RC Gear itself, Gyro’s vary in capability and therefore price. The more capable gyro’s available today are classed as “Heading Lock” / “Heading Hold” Gyro’s, in that the heading of the helicopter will not change unless you request it to by moving the transmitter stick. It is a kind of "Autopilot" to keep the model pointing in the same direction. All modern Piezo electronic Gyro’s offer good performance at a reasonable cost. Where possible, stay clear of older mechanical Gyro’s, as they cannot match the performance of the current Piezo and Heading Lock Gyro’s.

Radio Control Gear is marketed, advising of a specific number of channels. These channels refer to the number of functions that the RC Gear can operate.

A helicopter will require a set capable of 6 channels. Specifically these are:

Channel 1: Right & Left Cyclic (Controlling roll)
Channel 2: Forward & Back Cyclic (Controlling pitch)
Channel 3: Throttle (Controlling engine power)
Channel 4: Rudder / Tail rotor pitch (Controlling yaw)
Channel 5: *Gyro Gain (Sensitivity of the gyro)
Channel 6: Collective Pitch / Main rotor pitch (To control height)

*This will depend on the gyro purchased

Therefore you will require a transmitter and receiver with 6 channels as a minimum. You will require a transmitter specifically designed for use with helicopters. The reason for this is that a helicopter requires several special functions, for example: Channel 3 (Throttle) and Channel 6 (Collective Pitch) must be electronically mixed together so that when you increase the pitch of the rotor blades, the throttle is also increased to maintain the rotor speed. Generally non-helicopter designed transmitters do not posses this function.

Computerised or Standard?

A decision that you are going to have to contemplate is whether to purchase a standard set of RC Gear or the increasingly popular computerised sets.

The main difference between a computerised and standard transmitter is that the computerised effectively has many more functions and capabilities, accessed via the transmitters internal computer. Please don’t be immediately put off, thinking that the computer functions may be difficult to access or program. They are very simple to operate and can offer many advantages over the standard sets.

A standard helicopter transmitter will offer only the most basic requirements to enable you to fly:

The capability to mix the throttle and pitch together.
The capability to mix the throttle and rudder together to prevent yawing.
A facility to set the minimum and maximum amount of rotor blade pitch.
A facility to set a dual rate on the roll and elevator functions
(To set the maximum amount of servo travel on these functions).

A computerised transmitter will offer all of these as well as many other features that will enhance the accuracy with which your helicopter can be set up. It can also be used to fly Aeroplanes and gliders in addition to helicopters. One of the most important of the extra features is that a computer transmitter has a “model memory”. This model memory enables the complete settings of several models to be stored within the one transmitter. You can therefore own several different models and use the same transmitter for all of them, by simply selecting the correct model memory. Depending upon the RC system, the number of model memories can vary between 3 to 10. Some can even be expanded to store many more.

As stated earlier the additional features of a computerised system will allow your helicopter to be set up more accurately. The travel of all channels can be adjusted and you can set the helicopters pitch and throttle settings to the exact positions required at different points of stick position. There are other examples and advantages, but In short it will enable fine-tuning which is not available with a standard transmitters mechanical set up. A computer transmitter is not an excuse to rectify an inaccurate mechanical set up. You should always set up the Radio Gear as best you can mechanically, and then use the computer features to enhance this.

Which is the most suitable for the beginner?

To enable your helicopter to be set up to it’s true potential (and therefore have it fly more accurately) we would recommend that you should aim to purchase a computerised RC system. The additional cost involved is far outweighed by its greater capabilities that will benefit you throughout your learning curve. It will provide you with the ability to fly several different models and the option to diversify into Aeroplanes as well. There are many very reasonably priced computer systems available today. Most are fully capable of helicopter functions, however certain types are for Aeroplanes only so ensure you purchase the correct type. Remember that in addition, you must also budget for a suitable Gyro system. You will require 5 servo’s (so you may need to purchase an extra one) and a receiver battery pack of a suitable capacity. A final word regarding batteries, always use batteries of the highest quality which have been assembled by a reputable company and ensure they are properly charged before use. Purchase a battery checker (£10 - £15) to test the condition of charge in the battery before each flight. Alternatively you can buy an “on-board” checker which will monitor the condition while the helicopter is switched on. Never attempt to fly if you are in any doubt as to the level of charge left in the battery.