Electric Micro RC Helicopters

3-channel coaxial helicopters offer a good place to start getting into the RC helicopter hobby. They are stable - thanks to the coaxial counter-rotating rotor blades, quick to learn - thanks to the simplicity of the 3-channel design, and most important of all: not too expensive, so you can try it out and see if RC helicopter flying is something you want to spend more time and money on.

3 channel control means that you can control the torque of the motor, thus flying the helicopter up and down, the yaw to left and right by controlling the relative speed of the main rotor blades, and the tail propeller speed and direction which propels the helicopter forward or backward. That is what is meant by 3 channel control - there are three dimensions in which you control the helicopter. It is a little bit like a tank, which can turn around its vertical axis on the ground as well as go backwards and forwards and steer to the left and right, except with a helicopter, which flies, you can also control the hight off the ground.

Co-axial counter-rotating main rotors means that there are two sets of rotor blades, and these rotate in opposite directions. A traditional helicopter would only have one set of rotor blades, and due to the torque created by this blade the helicopter would spin wildly unless there was a tail rotor counteracting this torque. With a coaxial setup this is no longer necessary, since the torque created by the two sets of blades cancels each other out, due to rotating in opposite directions. This means that the helicopter becomes extremely stable - it does not want to yaw or drift in any direction by itself, thus enabling you maximum control.

There are some very cheap toy grade versions of these helicopters, some of which use infrared instead of proper radio signals to operate the helicopter from the transmitter. I would not recommend these, since infrared is unreliable and you might lose control of the helicopter in flight. It's better to spend a couple of bucks more and get a proper, hobby level quality helicopter, such as the one below, the Syma Alloy Shark.

With 4 channels the controls start getting more complicated - essentially the same as for a real helicopter! In addition to up and down movement and yaw (left and right turn), there is full cyclic control, which means that the pitch (tilt) of the rotor blades changes as they spin around. In fact, they tilt two times for each revolution. One time is when the blades are perpendicular to the body of the helicopter. When the blades are tilted at this location, the pitch controls forward and backward movement. We had that with 3-channel helicopters too, just in a different way. But when the tilt is changed when the blades are parallel to the helicopter body, the pitch affects sideways (left and right) cyclic, which means that the helicopter can now move left and right without rotating the body (yaw). So just like a real helicopter, it can move in essentially any direction at any time. That's pretty cool.

These helicopters have the same kind of coaxial counter-rotating rotor setup as mentioned above, meaning that they are very stable. When balanced and trimmed correctly, they do not drift or yaw in any direction. That means that it is very easy to get it into the air right from the start without accidents during take off. Control, once in the air, is tougher though - you will have to practice in order to master hovering and flight in any direction. But thanks to the coaxial setup, the helicopter will not by itself drift, so the only thing you have to worry about is the commands you give it through the transmitter.

The kind of micro electric coaxial 4-channel helicopters is in my opinion the Blade mCX. It's an extremely well-built, robust, and agile helicopter. I have made a whole separate page with more information about it, so check that out as well, but don't forget to keep reading here too.

Now we've moved away from coaxial counter-rotating main rotors, and into single rotor territory. That means that just like most real helicopters, there is only one set of main rotor blades. As mentioned above, coaxial helicopters are so stable because the torques of the two counter-rotating sets of blades cancels each other out. But with a single rotor, we don't have that luxury any more. That means that a tail, anti-torque rotor is necessary. This anti-torque tail motor counter-acts the torque created by the main rotor by pushing air in the opposite direction, so that the helicopter doesn't just spin uncontrollably. The tail rotor is also used to yaw (turn left and right) by adjusting the speed of the tail motor, or the pitch of the blades, depending on the helicopter configuration.

Having a tail rotor also means that there are a couple of more forces acting on the helicopter. You will notice, for instance, that the helicopter drifts to the right slightly, especially during takeoff. This is because the tail rotor pushes air to the right, thus creating a slight force on the helicopter pushing it to the left (by convention, the main rotor of a helicopter rotates clockwise, and thus the tail rotor pushes air to the right to counter-act the torque, although the opposite would also be possible).

Piloting a single rotor helicopter is thus significantly more complicated than a coaxial one. That's why I would strongly recommend that you start off with a coaxial helicopter and then moving to a single rotor one once you've mastered the flight controls, since you will have to be a lot more alert and respond intuitively to keep a single rotor helicopter hovering stably.

Last, fixed pitch means that the main rotor blades have a set, fixed, pitch which always creates lift, and to fly the helicopter up and down, the speed of the main motor is changed. Actually all the coaxial helicopters discussed above are also fixed pitch, but for single rotor helicopters there is also another alternative, which is called collective pitch; more on that below.

The by far best 4-channel, fixed pitch, single rotor helicopter I know is the Blade mSR. What sets it apart from other similar products is in my opinion mostly the extremely robust design and the very stable flight characteristics. This makes it an ideal starting single-rotor helicopter. I have in fact written a whole separate page on this helicopter too since I like it so much. Please read it, but don't forget to keep reading here, because there's more...

Even though 6 channels is more than 4, the controls for the helicopter are actually the same as those for 4 channel helicopters. The 6 channels is more of a technicality. What's more interesting is the collective pitch of the main rotor. With fixed pitch helicopters, up and down movement is controlled by increasing or decreasing the speed of the main motor, thus affecting the speed at which the main rotor blades revolve.

With collective pitch helicopters, though, the speed of the main motor is more or less constant, often slightly relative to the pitch of the blades, but the pitch of the main blades can be collectively altered, i.e. not only is the tilt of the rotor blades changed to allow for cyclic control (forward/backwards and sideways left/right movement), but also the amount of lift generated by the main rotor is variable. This allows great, precise control of the helicopter.

What's more, on collective pitch RC helicopters the collective pitch of the main blades can be inverted. Why would you wanna do that? Well, to fly upside down! Something a real helicopter could never do. This allows even more advanced, "3D" maneuvers by highly skilled pilots.

Great examples of collective pitch micro helicopters are the freshly released Blade SR, big brother of the Blade mSR, and the Walkera brand of helicopters such as the 4g3 and 4g6. But don't go buying one of these if you're a beginner! Unless you've mastered 4-channel, fixed pitched helicopter flight, you're likely to end up crashing these things. Except perhaps the new Blade SR, which is designed for extreme stability and marketed at people who have graduated from coaxial helicopters. With this one, you are able to skip the fixed-pitch single rotor step.