I’ve been doing a drone road trip this past month. Flown all across the US, it’s been a blast (Managed to fly 7 states in one day!!). I’m back home in Colorado. My birds are generally well tuned, no propwash overheating or oscillations. Between sea level and 3500ft (1000m) I can’t notice much of a difference except during extreme humidity.

At 1 mile / 1.5km I start changing props to a bit more aggressive pitch. With a loss of about 15% flight times. Generally still reasonable to tune.

When I seek out 8500-10,000ft / 2500-3000m everything goes out the window. I am almost afraid to fly 3” or smaller as I can’t remove extreme propwash and wind will sometimes make it insanely hard to lower altitude or return home. In addition the blade are overworking and motors run a lot hotter. My long range 8” handles about the same with 8x6 2 blade props as 8x3.8 near sea level, like a slow turd. The worst is about a 40-50% loss in flight times. The thinner air is less grippy and harder to stabilize. I have found adding an extra 500 grams with a monster battery helps my already heavy rig.

I know I’m up against physics but wondering if anyone has any tips. Basic PID tuning guides no longer seem to apply at high elevation. I haven’t found much info on this particular topic. Anything helps.

I have found some improvements by going with significantly lower kv motors.

Riding quads to fly kwads :-) Uses a DC inverter to charge batteries from the atv.
   

FWIW, I am experimenting with the “bigger” and lower kv. I am building a 950mm frame with the T-motor 5006 450kv. I have 15” and 17” props I plan on trying. I’ll let you know how that attempt goes.