OTXSIM debugging tool

Last updated 11 April 2021 - Mike Shellim


OTXSIM is a lua script for checking out your mixer design without the need for the actual model.

OTXSIM is designed to run in the Companion simulator. As you 'move' the sticks, the effect is shown on a live graphic of the model.

No configuration is necessary in most cases - the sim guesses the function of each channel from its label. GVAR values can be altered on the fly (the stored model data is not affected).


Main screen


OTXSIM version 1.2 (5 May 2020)

For Companion 2.2 and higher, with X9D profile



Download the script (once only)

  1. Download the script, and change the file extension from '.txt' to '.lua'
  2. Copy the script file into the \SCRIPTS\TELEMETRY folder of the SD Structure path (specified in Companion settings).

Install the script (once only)

  1. Start Companion and select a profile for X9D/X9D+
  2. Open the .otx file containing the model to be tested
  3. Select the target model
  4. In the Telemetry menu, scroll to bottom, set the first screen to 'script' + otxsim
  5. (Optionally) save the .otx file

Running OTXSIM

  1. Start the sim for the target model
  2. From the splash screen, press {long PAGE}


The following buttons/computer keys are used for navigation:

Mixer conventions

The surfaces are drawn assuming the following convention:

Individual surfaces can be reversed in the Configuration page.

Auto configuration

At startup, OTXSim looks at the channel names and makes an informed guess as to their function. For example, a channel name containing 'v' and 'r' is mapped to the right V-tail panel. Suggested control surface names for auto-configuration:

Configuration page

If the auto configuration fails, surfaces can be manually assigned in the configuration page.


OTXSIM is designed as a developement tool only. It's recommended to remove it from the final setup before flying.