Looking for INAV in one place: Configurator 9.1, firmware and the landing pages. [url=https://inavflight.net/firmware]INAV firmware[/url] is the page I send people when they ask where to start.
No need to hunt firmware mirrors. [url=https://inavflight.net/firmware]INAV firmware[/url] is the page I use, then Configurator to put 9.1 on the board. That is enough for a first plane or quad.
