Planning a Long Range Flight in Litchi

Disclaimer: if you are planning on doing a long range flight with your drone make sure you follow local regulations, such as CAA in the UK.

In this tutorial, I will use waypoint navigation in Litchi app together with its online mission hub for creating waypoint flights. I could, of course, create the whole flight in Litchi app but it’s much more convenient to do so on a PC using Litchi website https://flylitchi.com/hub.

Few things to bear in mind when planning such flight:

  • Make sure it’s no longer than 15 minutes including the flight back, such that at the end of the flight you have at least 30% of battery available. This is in case you have a strong headwind.
  • Use UAV Forecast website or their app to check for weather conditions, especially for the wind direction. You want to begin the flight into the wind so that on the way back you fly with the wind. Use many of the apps available for checking the wind direction in the area you want to fly (such as MyRadar, WINDY or tens of other similar apps).
  • Litchi is capable of completing the mission even if there is no signal from your controller. However, there are some limitations such as it will fly at the last commanded speed and the gimbal pitch will no longer be pointing to the POI.

Registering with Litchi

If you haven’t already got an account with Litchi, go to https://flylitchi.com/hub and create a new account. By doing so all the missions you create on the website can be synced with the mobile app.

Defining Points of Interest

Points of interest is a point in space the drone’s camera is going to be pointing at. If you are on the website you can specify a POI by right-clicking with your mouse.

It important that you specify the correct height of the POIs and remember that all heights in Litchi are relative to the point from where the drone takes off.

Defining Waypoints

Waypoint is the point in space the drone is going to fly over. At each waypoint you can specify the following:

  • Height
  • Speed
  • Curve size
  • The POI the drone is going to be pointing at
  • Direction of the camera
  • Other commands, such as start recording, taking a picture and even land.

It’s important to note that the heights between each waypoint are linearly interpolated. If waypoint 1 has a height of 10 metres and waypoint 2 has a height of 30 metres, the height in the middle between those 2 waypoints is going to be 20 metres.

The same doesn’t apply to the speed. The drone will always fly at the speed specified at the last waypoint.

Creating a Mission

Start creating a mission by specifying the points of interest you want to film.

Once you have specified all the points of interest start creating waypoints. Make sure that each waypoint is at some distance from each POI. By default, each waypoint will automatically be focused to the closest POI. You can, of course, override this behaviour by clicking on a waypoint and selecting the POI manually from the drop-down menu.

In some cases, you have to create waypoints without having to use POIs at all. The common scenario is that you have to fly along a long object, such as a wall. One method would be to create multiple POIs along the wall, but the camera will swivel from one POI to another.

To avoid that, create just one-way point and make sure the camera is pointing straight ahead at the POI. Note the heading and the gimbal pitch. Create another waypoint at the end of the wall, set the gimbal pitch mode to “Interpolate”, copy gimbal pitch value and the heading from the previous waypoint. This way the camera will be parallel all the time the drone flies along the wall.

Waypoint Speed

It’s best to leave the majority of the waypoints’ speed to “cruise speed” and only override the speed of the waypoints leading to or away from POIs. This way you can easily adjust the speed of the majority of the waypoints by changing the default cruise speed of the mission.

Always assume the worst case scenario when it comes to the speed of the drone, the way the DJI API works is that if the drone loses connection it will carry on flying at last commanded speed.

Waypoint Height

As mentioned before the height between waypoints is linearly interpolated and is relative to the point the drone took off from (the home point). To ensure the best reception and to keep the drone in sight increase the height of the waypoint the farther away the drone is from the home point (or from where you’re standing)

Putting it all Together

In my example, I will use Buckingham Palace in London. Word of caution, don’t even think of flying there with your drone, you will most likely be shot, arrested and put in a dungeon to rot.

Go to https://flylitchi.com/hub and register if you haven’t already done so. This will allow you to sync the missions created on the website with Litchi app.

Here is the POIs I want to visit.

Waypoints

Note that you can create a POI by right-clicking on the map with your mouse and make any changes by left-clicking on the POI. You can drag the POI to a different location and change its height

POISettings

And here is the flight plan.

Plan

I plan on circling around the statue with the camera pointing at the 1st POI, then fly the drone across the perimeter of the building. After I have done all of that I want to quickly return to where I took off and wait for the police to arrest me.

Now to make a perfect circle around the statue make sure that the Curve Size is set to the maximum value. Also, double check that all the 3 waypoints are pointing to POI number 1

Statue

The next step is to fly parallel to the facade of the building. This can be achieved by defining one POI and two waypoints

Flying Parallel

Note the heading and the Gimbal Pitch of waypoint 5. Select waypoint 6 and instead of selecting of “Focus POI” choose “Interpolate” copying the heading and Gimbal Pitch from waypoint 5. That way the drone will fly parallel to the building at all times.

Apply the same technique to waypoints 7 and 8, 9 and 10. Make waypoint 11 focus on POI 5 (just for the sake of it)

CompleteMission

Now we have a slight problem. The total mission time is 17 minutes which is way too close to the limit.

Click on settings and increase the Cruising speed to the point where the total mission time is about 10 minutes. In my case, that speed is 10.8 km/h

MissionSettings

You can now export the mission as KML 3D Path.

MissionOptions

That will allow you to see the mission in Google Earth

GoogleEarth.PNG

The final step is to save the mission. Then using the Litchi app make sure that it’s synced to your account.

Press on FPV in the top left corner, and if you are not already logged in it will prompt you to do so. Since I’m already logged it simply displays my username.

LitchiLogin.png

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