iNav users primarily have chosen it for it’s GPS features.
This means that the quad has to reliably see at least 8 satellites (some people will say only 6 is needed but on a fast moving object were some sats may drop out I believe 8 is the minimum working number)
This is fairly easy to achieve on a small quad, I have one on my TinyHawk, but the 120/180 size units are not as sensitive as the larger 880’s Best to fit one with a tiny battery included as it will store last positions and make the acquire shorter for next time.
iNav also needs a compass, this is more difficult on a small quad as it has to be seperated by about 50/75mm from high current carrying cables i.e. battery, ESC’s and motor leads.
In most cases the best option is to fit a GPS module with compass included (most are these days) and put it on a stalk above the battery. I was lucky with my HSKRC 280 I mounted it above the FPV camera and it worked well.
Setting up iNav is very similiar to BF, they are both ‘forks’ from CleanFlight. The GUI ‘Configurator’ are very similiar, PIDS and rates settings share similiar formats there are just extra parameters for RTH settings and mission navigation. Anybody who is familiar with BF Configurator will have no problem getting their head around it.
The configurator includes a tab to pre-plan a flight, called a mission, which you can then load to the craft and invoke on a TX switch. This is very similiar to ‘missions’ in Flight Planner for Ardupilot and the iNav ‘dev’ guys have got it running pretty good these days.
Hope this answers the question, There are tons of YT vids on using and setting up iNav.
