Tag Archives: opentx

RC Helicopter Curves

This is how I do my curves on my helicopters. It is very basic set up and the curves and speed my change from heli to heli. This can be a good baseline for setup and you may tune your own curves from here.

First before setting up any curves make sure your helicopter motor is disabled.

The first thing I do is set up 4 curves, 2 throttle curves and 2 pitch curves. First let us look at the Normal mode Curves.

Normal Mode

Normal Mode Throttle Curve
Normal Mode Pitch Curve


I have set the throttle speed for normal mode at 80% throttle. When you throttle up the head speed goes from 0 to 80% by mid stick (point 1). That why the head speed will be full when you start to add pitch. Pitch will be at 0 when the throttle is at  when the head speed is 80 %. After this point you will not be adding head speed only pitch, as you move the throttle stick up. This way  when you switch to Idle up/stunt mode  the heli will not hop or drop. Also while in positive pitch if you switch to Idle Up/Stunt mode the head speed and the pitch will be the same. Note about negative pitch on normal mode — I always put some negative pitch on normal modes in case you need to hold the heli down tight during spin up, in windy conditions.

Idle UP/Stunt mode


Idle Up Throttle Curve
Idle Up Pitch Curve

When you switch to Idle Up/Stunt mode. You should be in a mild positive pitch. All positions above the center point (point 2should be the same in normal mode and Idle UP. Speed and Pitch will be the same. This way the heli will not move when you make the switch between modes.

Once the heli is off the ground you should switch to Idle Up and keep it there for the duration of your flight. This pitch curve gives you much more control during autos.

Wireless Sim USB Modification

I did not want a wire from my radio to my sim usb. There were a few solutions for this but most were bulky and clumsy to use. I got a few parts and put one together myself. Saw the idea a few places, but wanted to write up how I did it.



The Parts:

Receiver 2.4G 8CH D8 Mini FrSky Compatible Receiver With PPM SBUS Output

Simulator 22 in 1 RC Flight Simulator Cable for G7 Phoenix 5.0 XTR VRC FPV Racing

The Mod

We need to prep the receiver for use with the USB dongle. We need to activate the PPM on the receiver by jumping the the PPM pads on the receiver, with a wire or a solder jump. (may be a little different depending on the mini receiver)

Next prep the USB board either take off the wire plug or leave it on and use the connections points. It is easier to remove the connector and it give you more room. Connect the pins as shown. (may be a little different depending on the mini receiver)

Once the connections are made tuck everything in nicely. Before putting the case back on I would bind it to a model and test operation.

Now you can use it. Enjoy.



Open TX Companion 2.1.xx for X64 Fedora


Since they only release a 32 bit version of the RPM form Fedora, I had to build the x64 bit version from source. Here are the steps I used to build it. You should be able to follow these steps even if you have no build experience. You just need to cut an past these commands into a Fedora terminal.  This is a how to of for OpenTX Companion on Fedora, although it should work for OpenTX Companion on CentOS andOpenTX Companion on Redhat also.

First you need to get everything you will need to build Open TX Companion 2.1 .

As root run:
dnf install git gcc svn qt qt-devel cmake patch xsd gcc-c++ SDL-devel phonon phonon-devel avr-gcc-c++ PyQt4 fox-devel avr-libc xerces-c-devel
Run the following commands as a normal user:
  1. git clone https://github.com/opentx/opentx
  2. cd opentx
  3. git checkout master
  4. cd opentx/companion
  5. mkdir lbuild
  6. cd lbuild
  7. cmake ../src
  8. make clean
  9. make

Now become root and run:

make install

You should have Companion 2.1 installed and ready to go.



How to add and test a LUA script to Open TX Companion

LUA scripts can make the Taranis radio even more powerful. Here is a little how to with LUA scripts and testing of those scripts. The scripts used in the demo are listed below.

How to add a LUA script to Open TX Companion

OpenTX Companion Testing Telemetry Scripts 

This is the Temp LUA script.



— Temp Screen
— Version 0.5 Brad Kelley
— setup for Trex500
local escTemp = 0
local battTemp = 0
local function background()
escTemp = getValue(“Tmp1”)
battTemp = getValue(“Tmp2”)

local function run(event)


lcd.drawText(1,0,’Trex500 Temps’,INVERS)

lcd.drawText(1,15,’Batt Temp:’,0)

lcd.drawText(90,15,’ESC Temp:’,0)

return { background=background, run=run }



Here is the  Head speed Calc LUA script.



— Headspeed Calc
— Version 1.0 Brad Kelley
— setup for Trex500
local maingear = 162
local piniongear = 14
local rpm = 18000
local gearratio = 0
local headspeed = 0

local function init()
gearratio = math.floor((maingear / piniongear) * 100 ) / 100
rpm = getValue(“RPM”)
local function background()
rpm = getValue(“RPM”)

headspeed = math.floor((rpm / gearratio) * 100 ) / 100

local function run(event)

lcd.drawText(1,0,’Trex500 Headspeed’,INVERS)

lcd.drawText(1,15,’Main Gear:’,SMLSIZE)

lcd.drawText(1,22,’Pinion Gear:’,SMLSIZE)

lcd.drawText(1,29,’Gear Ratio:’,SMLSIZE)


lcd.drawText(90,15,’Head Speed:’,0)

return { init=init, background=background, run=run }