OpenTX - Application Note 29
Helicopter Set Up with CCPM and flight Modes
Set up a model with CCPM (Collective, Cyclic and Pitch Mixing) and flight modes for a helicopter with a fly bar. The flight modes will allow smooth throttle and pitch transitions between modes.
The helicopter for this project is a CopterX 450SE and its receiver is a FrSky X6R.
For more information about the X6R receiver, refer to Application Note 13.
A standard helicopter model is first downloaded from the OpenTX University website and the set up procedure is followed for this helicopter. Modifications are then made to suit my preferences, including setting fade times between flight modes.
For background reading, refer to the following articles in the OpenTX University by Craig Oakley.
The following reference describes in detail how to adapt a model template and set up a helicopter.
This project uses the file CCPMTemplate.eepe that is downloaded using the link at the bottom of the ‘ccpm-for-taranis’ web page (reference 5 above). In this file are two model profiles. They are’ CCPMHeli’ and ‘CCPMHeliFM’.The second one CCPMHeliFM is used for this project. It contains CCPM programming and three flight modes. The features of this model are described next.
1. Swash type is 120° between servos.
2. Mixer channel 20 is used for the collective pitch.
3. Throttle Hold is controlled by switch SF.
SF↓ Throttle Hold, SF↑ Throttle Enabled.
4. The sound volume is MAX when the throttle is enabled.
5. The flight mode is selected by switches SF and SE.
If switch SF is in throttle hold, the flight mode is Hold. If switch SF is in throttle enable, the flight mode is determined by switch SE.
SE↑ Normal Mode, audio announcement using file ‘nrmmod’ = “normal mode”.
SE- Idle Up Mode 1, audio announcement using file ‘idleup1’.
SE↓ Idle Up Mode 2. audio announcement using file ‘idleup2’.
Note that the files ‘idleup1’ and ‘idleup2’ are not in the standard [SOUNDS] folder on the SD card. They have to be created. For audio file creation, refer Application Note 4.
6. Rate Mode is set by switch SG.
SG↑ performance mild, (weight = 80%)
SG- performance medium, (weight = 90%)
SG↓ performance aggressive. (weight = 100%)
7. Gyro mode and gain is set by switch SB.
!SB↓ Gyro heading hold mode, SB↓ Gyro rate mode.
The gyro gains for each mode are set on the Inputs screen on the Gyr line which controls channel 5.
After the file CCPMTemplate.eepe is downloaded, unzip it. In OpenTX Companion, use File, then Open to open the file.
Start the Taranis in Bootloader mode and connect it to the PC using a USB cable.
In Companion, click ‘Read models and Settings from Radio’. This creates a new window with all the current Taranis models and settings.
Right click on the model ‘CCPMHeliFM’ and select ‘Copy’ from the menu.
On the other window, right click on the model number where you want to place the helicopter and click ‘Paste’ from the menu.
Click ‘Write Models and Settings to Radio’ to transfer all the settings and models, including the new helicopter, to the Taranis.
With the new model now in the Taranis, it can be set up to suit your helicopter.
The name ‘CCPMHeliFM’ is changed on the Model Setup screen to suit the model. This model name becomes ‘CopterX450’.
The image I have chosen is Trex450.
This is the wiring diagram.
The FLVSS is a battery voltage monitor. For more information, refer to application note 19.
To bind the receiver, refer to Application Note 13.
See section ‘1 Adding Weights’ of reference 5.
Weights for each of the three performance levels are set on the Inputs screen for Ail, Ele, Rud and Col channels. Note that 34 is the maximum weight for aileron and elevator. Do not set values above 34.
See section ‘2 Setting the Heli Mix’ of reference 5.
On the ‘Heli Setup’ screen, the swash type is 120, the collective source is channel 20 and the swash ring is 100%.
See section ‘3 Setting the Mixes’ of reference 5.
The mixes are set as follows and for this project and do not need to be changed. Channel 20 is used for the collective.
Setting The Servo Reverses
See section ‘4 Setting the Servo Reverses’ of reference 5.
The servo reverses are set on the Servos screen as follows. Channels 2 and 3 are reversed for this project.
See section ‘5 Setting the CCPM Reverses’ of reference 5.
The CCPM reverses are made on the Heli Setup screen. For this heli, the longitudinal cyclic direction needed to be reversed. The lateral and collective pitch directions remain normal.
See section ‘6 Setting The Servo Limits’ of reference 5.
1. On the Mixer screen, temporarily set the cyclic weights to 0.
2. For each servo, set the servo arms as close to 90° to the pushrods as possible.
3. On the Servos screen, adjust the PPM centres so that the servo arms are 90° to the pushrods.
4. Adjust the lengths of the pushrods so that the blade pitch is 0°.
5. On the Mixer screen, return the cyclic weights back to 100.
6. Set the maximum collective pitch as follows.
Select the flight mode that gives the lowest collective pitch and then set the collective stick to the bottom position. On the servos page, adjust the servo min values to set the required minimum collective pitch. If the channel is inverted, adjust the servo max instead.
7. Set the minimum collective pitch as follows.
Select the flight mode that gives the highest collective pitch and then set the collective stick to the top position. On the servos page, adjust the servo max values to set the required maximum collective pitch. If the channel is inverted, adjust the servo min instead.
The flight modes are enabled by logical switches L2, L3 and L4.
Logical switches L2, L3 and L4 are true only in switch positions SE↑, SE- and SE↓ respectively and switch SF is up (throttle enabled). Note that there are no fade in or fade out times. These will be added later.
On the Inputs screen, the flight mode selects which throttle curve is used. The screen alternates between the following two displays to show the flight modes and then the curve numbers.
Also on the Inputs screen, the flight mode selects which pitch curve is used. The screen alternates between the following two displays to show the flight modes and then the curve numbers.
Flight Mode ‘Normal’ throttle curve TNorm.
Flight Mode ‘’Idle Up 1 throttle curve TIU1.
Flight Mode ‘’Idle Up 2 throttle curve TIU2.
These are the pitch curves for each of the flight modes.
The tail gyro gain is set on the Inputs screen. When switch SB is down, the gyro is in rate mode. When SB is in the middle or up, the gyro is in heading hold mode.
These values need to be set to suit your helicopter.
Now that the helicopter is set up and flying with the model software supplied, it is time to modify it to suit my preferences.
In the original model, the volume was set to maximum when throttle hold was off. I removed the following special function that controlled this. This was the function I removed.
I now control the volume with LS instead as described in application note 5
In the original model, all the fade times were zero. However, the main reason to use flight modes is to be able to switch between throttle and pitch curves without the throttle and pitch channels suddenly jumping from one value to another. I added one second fade in and fade out times.
Because the flight mode selects the throttle value from curves CV1, CV2 or CV3 on the inputs screen, when a different flight mode is selected, the throttle value fades from one curve to the other curve over a 2 second period, preventing sudden jumps in the channel output value.
The pitch channel is also controlled in this way.
Timer 1 controlled by switch SA as described in application note 2
Timer 2 set to persistent as described in application note 7.
Throttle is disabled when switch SF is up instead of down.
The throttle curve in normal mode is changed to create a smoother throttle control.
Audio messages were created for modes throttle disabled, normal, stunt 1 and 2.
Audio messages were also created for the gyro setting.
They were then implemented by the following special functions.
For information about creating and transferring audio files to the Taranis, refer application note 4.
The following text file was created and transferred to the SD card in the MODELS folder.
To make this file display when the model is selected, set the Display Checklist box to ticked on the Model Setup screen. For more information, refer to application note 1.
On the Inputs screen, the order of Gyr and Col was changed to be the same as the Mixer and Servo screens. This does not change any functionality but it is neater.