First iNav Build - Opterra 2M
In working toward solar airplane development we first want to try out iNav. We have chosen the following set of hardware to do this:
1) Airplane: Opterra 2M
2) Flight controller: FuriousFPV F-35 Lightning
3) Radio/FPV/Camera: DJI FPV V1 (Remote Controller, Goggles, Air Unit)
Below are some notes that we think would help us do it next time and might help someone else get through this process.
For each of the 3 parts, DJI Goggles, DJI Remote, DJI Air Unit, we had to get them connected to the computer and registered with DJI before they would work.
The F-35 has less soldering than most fixed wing flight controllers but it does have some. The F-35 has an online manual. Here were the wiring instructions for DJI. Note that Air Unit is NOT the same as DJI Ocusync but they use the same wiring picture for the cable to either.
And here is our real result. It is only soldering 6 connections, but I look forward to a flight controller where I don't need to do any. If anyone finds a flight controller for fixed wing that can run iNav and connects to a DJI Air Unit without any soldering, please mention in the comment section below.
The servo cables on the Opterra just plug into the F-35 flight controller.
We had to download iNav and then flash the firmware to the F-35 over micro-USB cord.
For the F-35 in iNav we set the port settings to:
Under iNav configuration scroll to GPS and turn to on and use for navigation and telemetry.
For receiver go to receiver tab and set receiver type to "serial". Set serial receiver provider to "SBUS". Serial port inverted to "off". Set serial receiver half duplex to "auto".
We told iNav that we had a flying wing. The following video shows how to setup iNav for a flying wing.
And the next video is part 2 of above:
To get the OSD (on screen display) working for DJI and iNav we followed the instructions to use the "Craft Name Hack" in the video. The DJI Goggles can display the craft name. The hack is that iNav can keep changing the craft name to display information such as warnings, speed, distance, etc. In configuration/other-features tick OSD to on. Under configuration/personalization/craft-name we put ":WDSTE" but video explains the options. In the DJI Goggles set "settings/display/custom OSD" to on.
In iNav under "CLI" you can do "dump" and then "Save to file" to save settings. Making regular backups like this can be a life saver if someone breaks something in the settings. Then you just do "Load from file" from a known good configuration.
The flight controller does not make the 5V for the servos (even with USB to computer and battery plugged in). The 5V comes from the servo connection to the ESC. So the ESC must be plugged in before any servos will work.
If anyone wants we can make our iNav dump of the settings available so you can just load them in.
We should have a maiden flight soon. Will post here when we do.
Update Apr 12th, 2021.
We got a nice day and went out to our launch site.
Put up a windsock to see how to line up the runway.
Put together the Opterra and did the final mount of the flight controller.
But the wires to the wing servos would not reach to the flight controller. We could plug in the ESC servo and so could test that we could arm. We could get GPS lock and our arm switch setup worked, and the DJI trick of putting both sticks down and toward the center, and it did arm. We could make the propeller go. But we will have to come back another day with servo cable extensions.
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