Wednesday, October 26, 2011

Helicopter Radio Setup

Introduction

Computer helicopter radios do a lot of the hard work for us now in flying a radio controlled helicopter. But they need to be setup carefully and accurately. You will normally require a 6 channel radio for a RC helicopter. These are, elevator, aileron, rudder, gyro, throttle and pitch. A computer radio will mix the cyclic servos to control the swash for you. It will also mix the throttle and pitch, dependent on your settings.


Some of the options can be overwhelming. Below you will find the main options that you need to know about, and what there purpose is. We will add at a later date some "Ideal" settings for particular helicopter/transmitter combinations. However, we encourage you to make your settings unique to yourself, this will allow for greater understanding of the operation of the helicopter, and for a more responsive and well behaved helicopter.

Revolution Mixing The Spektrum DX6i helicopter radio

If you have installed a Heading Hold gyro, you will want to inhibit this option, as the gyro will take care of it for you. If not you will have to do some trial and error getting this setting just rite.


Basically, as you increase the throttle of the RC helicopter, the torque is increased, meaning the tail will want to move in the opposite direction to the main rotor. What revolution mixing does is mix the throttle channel to the rudder channel. There by compensating for this movement.

Digital trims

To set this, you will want to be in a stable hover, increase the throttle and take note of the amount of movement. After landing again, change the setting by a percent or two, hover, and repeat, until an increase in throttle has little or no effect on the helicopters tail.


Allows you to choose between a 90 or 120 degree swashplate, dependent on your helicopter.

Revolution mixing

Controls the movement of the cyclic servos in response to stick movements. This is used in combination with a mechanical setup to get the swashplate level at all ranges of pitch.

Throttle Curve

The throttle curve maps pre-defined values of throttle power to your collective stick. Linear by default, this means that when your collective is at zero, your throttle will be at zero. Equally, when at 50% and 100% collective, your throttle will be at 50% and 100% respectively.

Swashplate selection

99% of the time however, you will not want a linear line, it will be curved, as the aim is to maintain a constant headspeed with a combination of this setting and the pitch curve (See below) The exact numbers for the throttle curve will depend on your flying style and helicopter.

Pitch Curve

Similar to the throttle curve, the pitch curve controls how many degrees of pitch your blades are exhibiting when the collective stick is at any particular position. Unlike the throttle curve, a good starting line for this is linear (0/25/50/75/100) for the five collective positions. You can make changes to this to change the sensitivity of the helicopter in hover for example, but you will also need to adjust the throttle curve to maintain that magical constant head speed.


Again trial and error to set up, and not needed if you have a heading hold gyro. This allows for different trims at different rpm modes (Idle up etc, more on this later).

Channel Reverse

As simple as it sounds, it allows you to make changes to the travel directions of the different servos.

Swash mixing

Like we all learned in mathematics, an exponential curve, increases or decrease at an ever increasing rate. So applying this type of setting to your helicopter cyclic controls means the area around the center of the sticks will be less sensitive than the extremes of the sticks. This will help in the hover, but allow for agile flight characteristics when chucking the model around in an aerobatic attempt.

Gyro Gain Servo reverse

The sensitivity of your gyro is controlled from this option. It may take a few hovers to get it spot on. But the tell tail sign of to much gain, is wagging of the tail on the horizontal plane. To low and the tail will be very sloppy, not holding position as well as it should be. Fine tune this for the ultimate tail hold.

Idle Up Exponential

The "switch of doom" as it is more commonly know, this has been known for more crashes than i care to mention. If you do not intend on using this and/or you are a beginner, make sure this is inhibited.


Essentially it allows you to set multiple options to different values at the flick of a switch. As an example, in normal flight, hovering etc a pitch curve giving 0 - 6 - 10 degrees of pitch is perfect, and with this a reasonable calm throttle curve. Now that we are coming out of the hover, and want to try out some 3D routines, we require some negative pitch, so having pre-set our idle up throttle and pitch curves, we can switch to a constant throttle value, and a pitch range of (-10) - 0 - 10. Meaning that just above centre stick we have a few degrees of positive pitch, and good throttle value for hovering. We can now flip the model and hover inverted, as we can use the lower half of the collective travel for negative pitch.

Gyro gain control

This is similar for a lot of the other values, including the gyro gain, these can all be set to a different value for idle up. Some radios will also have a idle up 2, it is the same thing, but allows for 3 separate settings.

Throttle Hold

If you ever need to do an emergency autorotation, this allows you to set a specific pitch curve, and access it at the flick of a switch, to allow you to glide your helicopter down safely.

Travel Adjust Servo travel limits

It allows you to set up how far the servos travel with a given stick movement. It allows you to set end points, so your servo doesn't keep moving when it should be stopping due to mechanical limitations.

Trainer (Switch)

Whilst held, allows for a second, connected helicopter radio to take over your flight controls. However, once released the controls are back in your hands.

Hover Pitch and Throttle (Adjustable dial)

Allows you to fine tune the pitch and throttle values whilst hovering. You should be aiming for around 1,600 rpm on the throttle and 6 degrees of positive pitch in the hover.


That just about wraps up our guide to radio setup. Check back soon for some pre-made settings for popular combinations, and a more in-depth look at some of the advanced functions and mixing possibilities.

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