Main rotor diameter
Helicopter rotor(s) diameter. In fact, this parameter primarily determines the dimensions of the machine in the working position; this is especially true for three- and four-bladed models, where the propeller cannot be deployed along the fuselage, reducing the width of the space occupied (although the blades can be folded, which eliminates this drawback). Otherwise, the diameter of the rotor is of secondary importance: it is selected by the manufacturer in such a way as to provide features corresponding to the class of the machine, and it is worth focus primarily on the general purpose and price category of the helicopter, and not the size of the propeller.
Number of channels
The number of control channels provided in the radio-controlled model.
Each such channel is responsible for a separate control function: the operation of the rudder, elevators, etc. For the simplest models, 2 – 3 channels are enough. Full control requires more channels. In advanced models, additional channels may be provided, the total number of which can reach 6 or more.
Gyroscope
The presence of a gyroscope in the design of the helicopter.
A gyroscope is a module that tracks the position of a car in space and its movement. In radio-controlled helicopters, it is used to compensate for gusts of wind, failures in mechanisms and other factors that create minor interference in control: for example, if the movement of air knocked the helicopter off course, the gyroscope reacts to this and returns the car to its previous position. This feature makes the control smooth and smooth, which is especially important for cars of a low-cost class, where it is not possible to use high-quality (and, accordingly, expensive) mechanical equipment. And in some models, the gyroscope is also responsible for more advanced functions: automatic hold in place when hovering, flying in the opposite direction when the signal from the remote control is lost, etc. At the same time, such equipment may not be installed in professional flight models, since it tends to reduce responsiveness and control accuracy.
Battery capacity
The capacity of the battery supplied with the electric motor model (see "Motor"). Indicated only for variants using branded batteries (see "Battery type"), measured in ampere-hours: 1 Ah corresponds to the capacity at which the battery is capable of delivering a current of 1 A for 1 hour.
The higher the battery capacity, the more time the helicopter can spend in the air, usually. However, the practical time of operation on a charge is largely determined by other characteristics of the machine — dimensions and weight, engine model and power, etc. Therefore, in most cases, this parameter plays a purely reference role, and only helicopters that do not have any significant differences in other characteristics (and even then very approximately) can only be compared in terms of battery capacity.
Battery model
Model of the original battery (see “Battery type”) for which the helicopter is designed. Most often, such a battery is supplied with the device. Data on the battery model may be needed if it is out of order and needs to be replaced, when looking for a spare battery or when selecting a charger (usually, charging capabilities are already provided in the standard package, but it is possible that a separate device will be required).
Dimensions (LxWxH)
General dimensions of the model. Note that the length and width are indicated only for the fuselage, excluding the main rotor. However, for ease of transportation, the blades are often made removable or folding.