I’am adrien from Réunion Island in the indian ocean. I’am a drone pilot here since 10 years and instructor since last year.
I work mainly for the film industry with dji products but this year is special ! I come back to Pixhawk for a heavy lift quadcopter to help fighting pests in the high lands of the island (rats). (i started my first ever build on a arducopter back in 2010).
The project is to fly mission with a heavy lift drone that carries a custom drop system and spread specific biocid on large area. So far, they use slingshot for remote area without being able to cover the whole zone.
So, i’d like to gather information about large heavy copters and benefit from your experience if you agree to give some advices. I will keep you up to date with the project and answer questions whenever it’s possible.
The setup (Quad) :
Gryphon 1400 super frame
Pixhawk 2.1 CubePilot black cube
4x Tmotor U13ii - Flame 180A - G32x11
MAUCH electrical accessories
12s - 2x 2x16 000mAh GenAce Tattu
FutabaT14sg
So far, i only have the controler and mounted it on a X8 900mm octocopter frame in order to familiarize with the tuning. First flight was good, very stable flight but need to tune ! Tried a full autotune but did not finish because of lipo capacity.
I’ve been flying a large 1400mm 12S Hybrid system for some time and they can be difficult to get stable. You will find they are quite different from flying a 900mm frame, although it is good that you are getting familiar with the tuning process on a smaller frame.
What I would make sure to do is follow the tuning guide https://ardupilot.org/copter/docs/tuning-process-instructions.html
Using that guide should get you stable enough flight to conduct an auto tune, you definitely won’t want to fly around using the default filter values.
Auto tune also might take a couple tries to get values you like on a larger frame, we had some issues with ours but it is flying well now. Your hardware selection looks good, T-motor and Mauch haven’t let me down yet. Although if you have the room and weight for it why not go for 2x 2x22 000 mAh Tattu for some longer endurance
Thanks for reply. FIrst, you’r right, i’ll take the time to be at ease with tuning on the small frame knowing that it can be really different on the big one. That’s the reason of this topic
And i’am reading this exact section for the third time now !
We decided to go on smaller lipos because of two reasons. FIrst one is the weight as we don’t want to exceed 25kgs to stay into a legal limits without having to ask for special permit here in france.
Second is that we calculate the number of drops and flights to cover a certain area and longer endurance doesn’t help here has we have to come back to the base to refill the drop system.
I’am only working on the vehicle and an engineer is working on the drop system. I will undoubtly mention this to the team as it can lead to futur collaboration.
If you want to save time and get a ready to work <25kg ready to fly copter you can contact me. We produce an heavy lifter quad that is already used by clients in S2 scenarii (agriculture) and can carry up to 10kg payload. It reach 40 minutes flight time with ~5kg payload.
Issues you must be aware of when building and flying drones with large diameter propellers.
#1 is stability as was mentioned before.
It is difficult to dial in a large diameter propeller drone because of the Moment of Inertia of large diameter propellers. They do not want to change speed, either faster or slower.
Drones fly and are stable because they can rapidly adjust the speed of the rotation of each propeller quickly. Large diameter propellers do not want to change speed. Its just physics.
My advice has always been if you want a Heavy Lift Copter, then use a single rotor, not a multirotor, and I sell multirotors. Single rotor systems can react quickly even with 6ft diameter rotors because the rotor does not change speed, just pitch.
#2 Wind, because the propellers do not react quickly, the drone will be unstable in high winds.
The large propellers also act as large areas for the wind to grab your craft and flip it around.
It does not matter how big the drone is, wind will affect it. Just think about the very heavy transport truck on the highway getting blown around and the small car is fine.
Hi Adrien,
if you have issues completing auto tune due to battery capacity, you can split the tuning process in the three axis. This can be done selectively in the parameters before each flight and works really well in my experience.
Hope this helps: spreadsheet created from the new tuning guide, plug in your props in inches and number of Lipo cells. Be sure to check the values it produces actually make sense and suit your craft.
These parameters are just a starting point before Autotune - you should also have fully read and understood the tuning guide.
Hello,
thank you this excel file it’s a good start point and really useful.
Maybe in the futur a function like that could be directly integrated in Mission Planner @Michael_Oborne like a wizard or a first setup pop-up?
Thanks a lot, i looked at the document and compare it to my personnal parameters based on the reading of diagrams. My values are really close to the ones giving by your spreadsheets.
It’s a good tool to prepare for tuning and checks basics parameters.
This morning, i modifed my parameters to fit to the one produced by the spreadsheet and it flex really nice.
The type of wandering can help you determine the cause.
It might not be the Parameters.
If the compass is not working perfectly the craft will try to correct is incorrect position and go in the wrong direction, then make a correction again and miss the point where it was suppose to be.
This is called Toilet Bowling. So watch the wandering and see if it is going around a center point, like being flushed down the toilet.
Check over your craft for any sources of magnetism. Use a cheap pocket compass to check for anything magnetic close to the compass. Once I found a steel bolt ( should not have been used) that had gotten magnetized that was close to the compass. When you are checking for magnetic issues, have the craft powered up. Items like Torroids can create fields that could cause issues. I have also found a voltage warning device that when the alarm went off, the speaker created a magnetic field that was measurable next to the compass.
