Over 4 days we covered 2000 ha (nearly 5000 acres) of undulating, forested and open country with a single Mavic Pro (2016 build) and 9 batteries. I ran the flights using a iPhone6+ and iPad mini and the standard Mavic RC and charged the batteries using the 12V car charger (one at a time), the 4 way DJI AC charger and a 15,000mAH battery (for the RC and devices).
Prior to that we’d only done projects of up 300ha and so it was quite a leap up and great learning experience.
The first step for me in managing to capture this area was in the flight planning. As I was running the flights at the maximum legal altitude of 120m/400’ (Australia for a registered user sub 2kg class UAV’s) and given the changes in relief and limitations of using this UAV (battery life and camera resolution) and predicted wind directions I devised 40 flight plans in GoogleEarth, each of which covered between 50-100ha.
With this I was able to manage the battery load, however it was dependant on my wife ‘ferrying’ batteries to and from the farm house where we had the DJI 4 way AC charger. I do have a large battery bag however I never considered using it when charging - I must say the ammo box idea sounds more practical so thanks for that! As soon as the first 2 batteries were used up my wife took those to the 4 way charger and I always had another on the 12V in the car. We had a packed lunch/snacks and a thermos and did 8 hour days.
The main thing that made this whole flight possible was paying close attention by recording the battery consumption of each and every run (including flights/distances to and from the take off point), having the take off position centred in the flight plan (also paying attention to maintaining an adequate flight altitude considering changes in relief) and ensuring that the UAV returned home at no less than 30% battery level or following the completion of a run — I found that if I let the app manage that then the UAV would leave a run midway and then the app would go to the start of that run and add time and additional photos to that flight plan, increasing battery use and the number of duplicate photos to upload and process.
We averaged between 18-20mins flight time out of each battery and at the end of each flight plan I downloaded the images saving an enormous amount of time at the end of each day when I was uploading them to DroneDeploy. This process took about 5 mins per flight and all aided charging time. It was also a good check to see that everything went well with each flight plan and gave me a breather from the concentration involved whenever flying. Then we drive to the next take off point and repeat.
At the end of each day I would then put everything on the chargers at the farm house so every battery and device was at 100% at the start of each day.
This all worked well - the only changes I made subsequently were to buy a 2 jack 12V jack for the car and another 15,000mAH battery for the RC and devices. I also purchased a 3 way aftermarket AC charger which apparently charges 3 Mavic batteries in 1 hour. If this worked then I would consider connecting an inverter to the 140aH second battery I have in the Hilux and have this system charge the batteries in the field rather than running back to the closest AC plug. That way one could do this quite a lot easier and without the aid of another person (though I do love being with my darling!). Running the latter in flight mode definitely helped too.
Last week I completed a 300ha flight over 4 days, this time at 75m altitude and with GCP capture. I did 4 flight plans that were around the same area and laid out GCP’s (using an EMLID Reach RS Base and Rover) at 160m centres on a grid that I’d also planned to reduce time. I used a quad to get me around and this saved a lot of time in laying out the GCP’s, as did having a GCP grid and I used Garafa’s GPS Kit app to navigate from point to point. Though this was a very different mission to the 2000ha job, it was a breeze by comparison and I had the 2000ha job to thank for that as I learned the limitations of the equipment I was using and how to optimise battery management whilst in the field.
Thanks and all the best with your 5000ha project.
Darren J. Doherty
DroneDeploy #Flylanthropy Partner