Guide To Controlling Your Remote Control Helicopter
The number of channels a transmitter has determines the number of individual things on the aircraft that can be controlled. For example, one channel for throttle, one channel for up / down, one channel for pitching forward / backward, one for banking left / right and another for yaw. This is the case with a helicopter, where 5 channels are required for flight. (4 on a fixed pitch machine like the LMH - See fixed pitch in glossary)
The reason you would want more than 5 channels is so you can adjust more things from the remote without having to land or approach the helicopter. Some people have a control to adjust the fuel-air mixture of their engine while in flight for example, you can also tune the sensitivity of your gyro by using yet another channel. Some people have a governor to control the RPMs the engine is running at, and turning this off and on and picking a preset RPM requires yet another channel.
A beginner, strictly speaking, could get away with a 5 channel remote, if he could find one, but since using the 6th channel for tuning the gyro is so common, it's considered a standard requirement.
Also, because the people who want more channels are generally more advanced, radios with more channels tend to also have more features and customizations. Some that come to mind are the number of programmable points on a throttle curve, number of flight models and number of programmable mixes. These features tend to drive up the price drastically as you add channels, the Futaba 4 channel is less than $200 while the 9 channel is more than $1500!
There are two kinds of transmitters out there, computer based ones and non-computer based remotes. You can find non-computer remotes up to 6 or 7 channels, but usually an 8 channel remote will be computer based if it's not extremely old.
The benefits to a computer remote are many: You can store multiple models in memory, so that you can use your one remote to control several different rc things without having to re-adjust all your settings on the remote when you switch between them which is what you would have to do with a non-computer transmitter. Generally, all of your settings (revo mixing, hover pitch curves, throttle curves, rudder offsets etc) can be more finely tuned for better flying characteristics. You don't need small screwdrivers to adjust the settings like you may on some other remotes. The switches on a computer remote can usually be programmed to do many different things.
I highly suggest that if you're only going to get a 6 channel remote, that you get at least a computer based one, such as the Futaba 6XH or better yet the JR 652. In this case, the JR652 has some features that will allow you to use it longer before you need to upgrade to an 8 channel for advanced aerobatics.
The switches are used for different flight modes, such as normal flying, and high performance or inverted flying. Some switches are on their own channel and are used to 'do' things on the helicopter, while others just change the way an existing channel behaves. Some of them are used to adjust the rotor speed, the throttle curves (see glossary) and control sensitivities. These switches are not required for regular flight and most beginners wont use them until they've mastered forward flight.
The most common of these switches (even for beginner remotes) is idle-up, throttle hold, and possibly dual rates. Almost all helicopter remotes have these two or three switches. They're also listed in the glossary.
For regular flying, only the two sticks are used on the remote control.
The left stick is used to control the collective (up and down) by moving it up and down as well as the rudder (yaw left and yaw right) by moving it left and right. While the right stick controls the cyclic left and right (bank) by moving it left and right and the cyclic forward and backward (pitch forward / backward) by moving it forward and backward.
Moving the left stick up and down actually controls two things: the collective (pitch on the main blades) and the throttle. As you add pitch to the blades, you need more torque to maintain the rpm's of the blade, so these two are mixed to help maintain a steady rotor RPM. The problem that this makes is that as you add torque, you need to add rudder to compensate for the torque. This is where revolution mixing comes in, as you add throttle and collective, you can set your radio to also add rudder to compensate for the change in torque. This is called "Revo Mixing."
Depending on how fast the helicopter is going and in which orientation it is flying, the controls behave differently. For example, in a hover the elevator controls if the helicopter moves forwards or backwards, and collective controls altitude, but these two are the opposite while in forward flight because the faster you go, the more the rotor disk starts behaving like a wing and the collective, more like a propeller.
Here is a chart describing what the controls do when...
|Hovering||FAST Forward Flight|
|Tail Rotor||Controls yaw||Controls yaw, coordinated with turn rate|
|Aileron||Controls latteral movement||Controls turn rate|
|Elevator||Controls forward / backward movement||Controls altitude|
|Collective||controls height||Controls Airspeed|
These are merely extreme circumstances, there is always a blend of these two phenomena, and the closer you're to one extreme, the more the helicopter will act as I've listed... in the middle, when you're merely moving forward moderately, they both apply to a degree. Remember that when you use elevator to increase your altitude, you decrease your airspeed and get closer to the hovering rules.
Also, when you're flying in a different orientation, like backwards or upside down, the controls do the same thing, but feel "backwards." This is because when you're flying backwards, and you want the helicopter to turn right, and it does, it turns to it's right, which is to your left and even though your eyes want it to go the right, you need to move your hand to the left. Here is a chart to show you which controls "feel reversed" in different orientations.
|Upside Down Forwards||R||N||R||R|
|Upside Down Backwards||R||R||N||R|