From your experience/ observations: What are the main specific reasons DIY mini-uavs crash & recommended equipment/procedure to address it(point form)? This discussion thread will serve as guideline for amateur uav designers, system integrators, operators, hobbyist etc. It contains the most likely failure modes to worry about on your uav & the solutions. These statistics are brought to you, through the magic of crowd sourcing. This is a very important question since uavs are being integrated into the NAS by the FAA. Any thoughts(specific points, in point form preferred) ?
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1. Many crashes occur on the first flight.
- Control list.Each point must be made.
- Hold uavs in hand, give 50% throttle and check that all the movements are correct.
2. Problems during normal flight:
- Checklist of software and hardware.
- Clear documentation. eg labeling of flight mode on the radio. An egg timer for flight time.
- Switch for RTL, if you encounter problems, aviation-related or land-related.
-Use of incorrect gauge wire for power system. My first DIY quad was drawing 50amp and it burn the wire AND the tiny circuit board.
-Loss it in the sun.
In my experience
1 - User (pilot errors and faulty autopilot/GCS configuration)
2 - Radio range problems (closely related to 1.)
3 - Not enough power to return home (also caused by 1.)
4 - Propeller
5 - Motor electronics and hardware
6 - Equipment/sensor interference
7 - Wire problems
8 - Autopilot/radio electronics failure
9 - Battery failure
10 - Software (when using official stable versions)
Note: An inexperienced builder would most likely have stuff like wire problems and equipment interference higher on the list.
I can only speak from our own experience, but I believe the majority of crashes are caused by "setup" issues and lack of understanding of the technology and lack of following common sense procedures. We have spent significant time developing procedures for commissioning, tuning, testing and flying. Risk management is everything.
I am always amazed at the lack of checklists that are freely available. This may be one reason why there are so many crashes. I have attached our multirotor pre-flight. Please feel free to comment.
trying to attach file
Pre-Flight Multi R5.pdf
Absolutely fantastic checklist ausdroid, thank you for sharing with us!
Nice one ausdroid.
A lack of knowledge of the principles of flight needs to go in as well.
We sometimes see some shockingly prepared overloaded fix wing systems around here. Folks are surprised when they don't fly well.
There are thousands of pages of information on that topic out there going back before 1903.
This is a great idea and if we can manage to come up with a good list of ten items and how to address them I will be happy to prominently present it on my drones are fun web sites.
Of course the obvious big one is operator error or perhaps in our case, operator - builder - flight preparer.
But that is really a cop out covering a lot of ground.
I also think a really big one is expecting flaky hardware grade complex equipment (especially electronics and assorted radio and GPS connections) to perform more robustly than it does.
Check lists will help, but a thorough in depth knowledge of the aerial vehicle and its capabilities and limitations are also really useful.
I look forward to seeing what you all come up with and will be happy to help assemble an appropriate list - it could be a big help to everybody.
Great idea J'Rome.
Best Regards,
Gary
I fly mainly fixed wing UAV's but it always amazes me that "others" build a UAV load an auto mission and then the plane falls out of the sky. Then they get upset! or they do damage.
The real important process is not the flying but the preparation and then the gradual testing and commissioning of the system, note system not aircraft.
So
1) prepare the aircraft -CG, control throws, servo directions, hinges, wiring, motor mount, propeller, battery mounts wing fixing etc.
2) Test fly in Man or without the APM / pixhawk set up trims etc,
3) add APM/ Pixhawk and telemetry, check everything works correctly and nothing causes any interference.
4) Modify any basic settings to obtain correct operation, calibrate the radio and the failsafe. Verify everything works,
5) fly under MAN control and test RTL , loiter and circle. test radio failsafe, test battery failsafe.
6) tune the controller and keep tuning until it works correctly and reliably.
7) test a basic box mission and adjust your settings.
8) test takeoff, landing etc
9) learn to read your telemetry logs and understand what is happening to the aircraft.
10) before each flight test your systems, maintain the aircraft and charge the batteries. check the motor, propeller and wiring. maintain it the same way you would if your body was going to be in the plane!. check everything after you land look for bad bearings , hot motors , cracked props loose hinges / control horns.fix them!
I use this process an all the aircraft we build and it allows each section to be completed in a considered and repeatable way. you must understand the airplane to have any chance of avoiding failures.
to do this correctly you need many flights under RC only and some with the AP, this investment in time will help you to protect your aircraft and your wallet.
biggest cause of crashes? lack of flight preparation and correct planning, too much reliance on "Buy and fly"
Droid Planner 2 has basic check list incorporated into the application.
Pre-flight checks are good, but I like to perform a post-flight check too...I look for hotter then normal motors and escs, loose wires, etc.
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