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'Gulp' flying wing in action over Wales

Ethos programming - quick start

Introduction

If you're new to Ethos... well, you've come to the right place! In this article, I will explain how to program a simple model - a flying wing, like the 'Gulp' in the heading photo. Along the way, you'll learn three key skills:

These will form a standard workflow for all your setups.

Create the model

The 'new model' wizard makes it easy to create a basic setup. It supports quite complex model configurations, however we're going to use it for a simple flying wing. So let's get started!

  1. From the main screen, press the aeroplane icon, and choose 'Model select'
  2. Swipe left and touch '+'. The first page of the 'new model' wizard is displayed.
  3. Choose either the 'Glider' or 'Airplane' section.
  4. Configure the model as follows:
    • two ailerons
    • no flaps
    • no tail
    • no motor
    configure model

    New model wizard

  5. Finish off by giving the model a suitable name.

The wizard creates a new model with Ailerons and Elevators mixers. Each mixer outputs to CH2 and CH5, so we'll use those channels for the elevon servos.

Set the servo rotation

The wizard may be clever, but not so clever that it knows what servos we're using. So the next task is to check and if necessary fix the direction of rotation of each servo.

  1. Connect up the servos to receiver channels 2 and 5. The order is not important.
  2. Switch on the receiver.
  3. Move the elevator stick and observe the elevons…

    If both elevons move the correct way, say 'Woohoo' and skip to the step 4.

    If both elevons move the wrong way, then: open the Mixers menu, edit the Elevators mix, and reverse the sign of weight. The change will propagate to both channels.

    reverse sign of weight

    Change the sign of weight

    If only one elevon is wrong, then go into the Outputs screen and edit the corresponding channel: change the direction from 'Normal' to 'Inverted'.

    reverse output

    Reversing the direction of a channel

  4. Move the aileron stick. The ailerons will either both be correct, or both wrong. If they move the wrong way, open the Mixers menu and edit the Ailerons mix, reversing the sign of weight (the change will propagate to both channels).
  5. Check that the elevons respond correctly to both pitch and roll commands.

We're making progress!

Calibrate the outputs

The next task is to (a) calibrate the end points and centres of the elevon channels, and (b) to match up the responses on the left and right sides.

First, we configure the mixers and trims in preparation for the calibration.

  1. In the Mixers menu, go to the Elevators mix. Make sure that weight is set to 100%.
  2. Centre the elevator trim.
  3. Repeat steps 1 and 2, for the Ailerons mixer and trim.

Next, we do the actual calibration:

  1. Go to the Outputs screen.
  2. For each elevon channel, adjust min and max to provide the maximum possible movement subject to mechanical limits. Do this using the elevator stick so you can see any differences between the left and right sides. Reduce min and/or max as necessary so the left and right sides match precisely.
  3. Adjust the centres (subtrim) of both channels
    adjusting the end points and centre

    Adjusting servo end points and centre

Well done! The outputs are now calibrated, and the elevons should track nicely, regardless of mechanical differences. However the movements will be greater than is desirable for flight — we'll fix that in the next section.

Finalise control surface travel

The last task is to finalise the travel in response to pitch and roll commands. This is also called 'adjusting the rates'.

  1. Go to the Mixers screen
  2. Highligh the Elevators mix and open the mixer editor
  3. Adjust weight for the required elevator movement.
  4. If you want more up than down (or vice versa), then adjust the Diff parameter.
    adjusting elevator rate

    Adjusting elevator rate. Adjustments propagate equally to both elevons.

  5. Repeat the above for the ailerons mixer.

Failsafe

That's all the programming done. Don't forget to set the failsafe (in the RF System page), and then you'll be ready to fly...And if you don't have a flying wing, don't worry - the workflow described above will be similar for all your models!