Comparison Na-Na IM189 vs Na-Na IM190

The layout of the propellers used in the design of the helicopter.

— Classic. This scheme assumes the presence of one main rotor on the main axis and a small tail rotor on the tail. The tail rotor compensates for the torque from the carrier (without such compensation, the helicopter would turn in the direction opposite to the rotation of the main rotor), and is also responsible for course control — turns left and right are carried out precisely by changing the tail rotor thrust. Helicopters of the classical scheme are more complicated and more expensive than coaxial ones, and are also more demanding on control accuracy; on the other hand, they have more manoeuvrability and are better suited for aerobatics, including complex. Therefore, this design is typical mainly for advanced devices of semi-professional and professional class.

— Coaxial. The name of this scheme is due to the fact that such helicopters have two rotors located on the same axis, one above the other. The propellers rotate in opposite directions, which makes it possible to dispense with the tail rotor and use all the engine power to create vertical thrust. However, in most cases there is a small screw on the tail — but, unlike the classical scheme, it provides control of the helicopter in pitch, and not in the course, and does not rotate constantly, but only if necessary, tilt the car forward or backward. Coaxial circuit...models are much cheaper and easier to manage than classical ones, but the freedom of manoeuvre in them is limited. Therefore, this option is considered optimal for novice users, as well as amateurs who do not claim to be professional pilots.

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.

The type of power source required to operate the helicopter. Note that such sources are required not only for models with electric motors (see "Engine") — any car needs electricity at least to power the radio signal receiver.

— AA. Replaceable cells of a standard size, popularly known as "finger-type batteries". In this standard size, not only rechargeable batteries are produced, but also disposable batteries, which makes it possible to choose: either to buy additional batteries every time as needed for relatively little money, or to pay a large amount for batteries once, but not to spend money in the future. Further expanding the choice is that AA elements have different characteristics and price, but are completely interchangeable. The main advantage over original batteries is the ability to quickly replace dead batteries: they are sold in almost all stores with “household trifles”, and the process itself usually takes less than a couple of minutes. On the other hand, the power of such a power supply is quite modest, and the elements themselves usually require several even to power on-board electronics. In some models, AA elements may be included in the package, but most often the owner of the car has to buy them on his own.

— Ni-Mh. This category includes batteries made using nickel-metal hydride technology and not related to any standard size — that is, having an original shape and characteristics and most often initially “sharpened” for a specific...helicopter model (or series of models). By themselves, the "original" batteries for the most part surpass AA cells in terms of characteristics and allow you to create models with electric motors of quite impressive power. Specifically, nickel-metal hydride batteries are notable for their low cost, reliability, good capacity, no "memory effect" (drop in capacity when charging an under-discharged cell), and resistance to temperature extremes, which makes them very useful for outdoor use. Among the disadvantages are storage requirements: such batteries cannot be stored completely discharged for more than a few days.

— Li-pol. Batteries of the original form, made using lithium-polymer technology. For the original form, see above (Ni-Mh). With regard to this technology, it allows you to create batteries with high capacity, small size and weight and without the "memory effect"; its main disadvantages in the case of radio-controlled models include sensitivity to low temperatures, as well as a rather high cost.

— Proprietary battery. This category includes all batteries of the original standard size (see subparagraph "Ni-Mh" above), for which the manufacturer did not specify the manufacturing technology. They may use one of the technologies described above, or another.

Operating time of an electric powered helicopter (see "Engine") on one battery charge or on one set of batteries. This parameter is rather conditional and approximate: it is usually indicated for optimal operating conditions, with a uniform low load on the engine (most often for hover mode), and when using replaceable cells — for high quality batteries. Accordingly, in fact, the operating time may differ markedly from that stated in the specifications. Nevertheless, this indicator quite reliably describes the battery life of the car, and different models can be compared according to it.

The frequency at which the helicopter control transmitter operates.

— 27.145 MHz. One of the frequencies used for radio remote control for a long time; in some CIS countries it is even reserved by state regulatory bodies for this very purpose. Such transmitters are relatively inexpensive, but suffer from one serious drawback: they do not provide channel separation when several consoles are operating in close proximity to each other. In other words, if the helicopter stays in the coverage area of two transmitters, the signals from them will be mixed, which is actually equivalent to a loss of control. This is most often unimportant in "recreational" flights; however, at competitions and other public events where several cars can be in the flight zone at the same time, very unpleasant and even dangerous situations can arise. You can avoid such situations by developing a common frequency grid and using interchangeable crystal oscillators for consoles — but such features are not always available. As a result, this frequency is gradually being replaced by the more advanced 2.4 GHz standard, not only among professional, but also among amateur models.

Separately, we note that transmitters with frequencies of 35, 40 and 75 MHz can also be found on the market; according to the main features, they are completely similar to the described 27.145 MHz and differ only in the operating frequency.

— 2.4 GHz. Today's most advanced communication standard used by remote control helicopters. Its main feature (and difference from the above options) is the possibility of normal operation of several transmitters of this format in close proximity to each other. To do this, various technologies are used that provide automatic distribution of receiver-transmitter pairs over their own channels (similar to how it happens, for example, in mobile communications). Theoretically, the 2.4 GHz band may be more prone to interference, as many modern electronics work in it (in particular, Wi-Fi and Bluetooth modules); however, thanks to the distribution of channels mentioned, such problems arise only in very unfortunate cases, but are solved easily and quickly. In addition, due to the coincidence in frequencies with the Wi-Fi standard, models for such remotes can be easily controlled from a smartphone (see below).

The greatest distance between the remote control and the helicopter at which the remote control transmitter is still able to guarantee normal controllability of the model. Note that official specifications usually provide data for perfect conditions: full battery charge, no obstacles in the signal path, extraneous interference, etc .; in fact, the range may be somewhat less. However, by this parameter it is quite possible to compare different models with each other.

The higher this indicator, the further you can let go of the helicopter from the remote control, the less often you have to move to keep control. However, a large range means not only a long range as such — it also speaks of a good signal penetration, its ability to pass through various obstacles. At the same time, powerful transmitters require appropriate power and large antennas, which affects the weight and dimensions of the console.

The type and number of batteries needed to operate the helicopter control panel.

— AA. Replaceable batteries, colloquially known as "AA batteries". They are available not only in the form of disposable batteries, but also in the form of rechargeable batteries, are produced under various brands that differ in price and quality (which provides freedom of choice), and finding such elements on the market is usually not a problem. The power and capacity of AA elements are relatively small, but in most cases they are quite enough for normal operation of the transmitter for quite a long time. Usually, modern remotes require several of these batteries — usually 2, 4 or 6.

— AAA. Also known as "pinky". In fact, a smaller version of popular AA elements (see above); has the same key features, but differs in more compact dimensions and, as a result, somewhat reduced power. This option is typical for low-cost class models, with a small range of the remote control.

The ability to use a smartphone(and in most cases a tablet) to control the helicopter. This function involves installing a special application on an electronic gadget, which provides advanced features compared to a conventional remote control. The specific set of such capabilities depends on the model, it may include, in particular, transferring data on altitude, speed, heading, battery charge, etc. to the smartphone screen, broadcasting video from the onboard camera, recording flight tracks, executing pre-compiled programs by the machine and much more. Communication is usually carried out via Wi-Fi, and the range may differ markedly from the numbers stated in the characteristics of the helicopter, since in this case it depends on the capabilities of the smartphone, and not the complete remote control.

Modern smartphones use different operating systems, and for normal operation, the helicopter must be compatible with the corresponding OS. Specific options might be:

— Android. A very popular OS used by a huge number of smartphone and tablet manufacturers, from giants like Samsung and LG to little-known Chinese brands. Note that there are many versions of Android on the market, including deeply customized and even frankly outdated. Therefore, if your gadget uses proprietary firmware or an old version of the system, you should separately clarify its compatibility with the selected helicopter (more precisely, with a propri...etary model control application).

— iOS. Apple's proprietary mobile OS is used exclusively in "apple" electronic devices — iPhone smartphones, iPad tablets and iPod touch players; all these gadgets can play the role of a remote control for the model. iOS is notable for its uniformity on all devices, as well as the speed and mass nature of updates, due to which there are practically no problems with the compatibility of electronics and helicopters.

Most models with smartphone control are compatible with both platforms.

The presence of lighting effects in the design of the helicopter — coloured lights, headlights, searchlights, etc. Such effects play mainly an aesthetic and entertaining role, they give the model an original appearance. In addition, the backlight makes the device more visible, which can be useful when flying at dusk. And the largest and most advanced models can have a full set of navigation lights, like on a real helicopter — red on the left, green on the right, etc.