DJI Mini 3 Pro: What Speed to Fly at

DJI tell us that in dead calm the Mini 3 Pro's battery gives its longest flight time when the aircraft is flown at 21.6 kilometres an hour, which is 13.5 mph. But if the speed is increased somewhat the distance the aircraft can travel might actually be greater despite the shortening of the flight's duration. To investigate this a Mini 3 Pro user living not far from me recorded the screen display of a flight in which the beast was flown at 15 mph for a few minutes and then at 20 mph, so that depletion of the battery could be studied later. I give the relevant video file here, so that those that care to do so can analyse it for themselves. To spare folk the trouble, my own appraisal of the video appears below. There are a good few limitations to the procedure, and substantial improvements could be made. But let us look at what seems to be indicated:
At 15 mph the battery drained from 85% to 71% in 3 min 52 seconds, which would correspond to 100% depletion in 27.6 minutes, and give 6.9 miles of flying.
At 20 mph the battery drained from 67% to 52% in 3 min 45 seconds, which would correspond to 100% depletion in 25.0 minutes, and give 8.3 miles of flying.
Not shown in the accompanying video was an RTH at a precisely controlled 23.3 mph. The battery's charge dropped from 37% to 32% in 49 seconds, which would correspond to 100% depletion in 16.3 minutes, and give a range of 6.3 miles.
So far as they go these results indicate that the speed for the greatest distance flown is somewhat greater than DJI's published 13.5 mph, but speeds much over 20 mph will shorten both the flight duration and the range. Note that at the speed for longest duration, 13.5 mph, the distance that could be flown, if you achieved DJI's elusive 34 minutes, would be 7.7 miles.
The video shows that when the aircraft was flown at 20 mph the battery ran down less quickly when it headed south (towards the hills) than north. Possibly there was a slight north wind, though the day was about as calm as we get in these parts. To minimise the possible effect of wind the Mini 3 was flown round in a circle, so as not to be consistently into wind or down wind.
The battery got warmer during the flight, and changes in temperature alter the battery's characteristics. A prolonged flight at only one speed might have allowed the effect of temperature change to be gauged.
The aircraft's speed was never quite kept steady at the intended values, despite good intention.
I have assumed that a given piece of flying, if it drains the battery from 80% to 70%, would also drain the battery from 60% to 50%, or 45% to 35%.
These shortcomings and uncertainties call for more testing, preferably by folk in parts of the world where still air is more readily available. Where I live the only reliable way of getting still air is to build a house round it.

[@eprohoda]

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