WARNING - Multirotors can be dangerous! - RC Groups
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May 31, 2014, 11:36 PM
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JohnnyRobot's Avatar
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WARNING - Multirotors can be dangerous!


Hey everyone,

I want to share my story. I'd like for everyone to see this and be reminded that safety is THE MOST important element to consider when working with these machines.

It could be that I'm an idiot. Whether I am or not, it's important to know that this could happen to anyone given the right circumstances.



I was trying to diagnose an issue I had with the motors not arming.

I thought it was due to the battery failsafe. What it actually ended up being was the throttle signal was reversed. My controller entered ESC calibration mode without my knowledge.

When my testing moved on to the transmitter, the battery was still plugged in from the battery failsafe testing. (I usually unplug it for safety reasons)

I was frustrated, angry, and not paying attention. It's one of those moments when you just need to put everything down for a while and come back to it later with a clear head.

It took off from the table, and I grabbed it to protect my face and neck. I aimed for the center but it all happened so fast.



My pinky finger on my right hand was cut 40% of the way through. There are also 3 deep lacerations on my right palm.

My left hand has 2 deep lacerations. One of which would not stop bleeding, even with gauze, up until it was stitched.



Luckily, I still have all of my fingers in their entirety. No tendon, bone, or major nerve damage. My Pinky is numb at the tip, but the doctor says the sensation will likely go away.

For now... I'm fine. Harsh lesson learned. Even if you're frustrated as hell. ALWAYS stop and think about safety. Please.
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Jun 01, 2014, 06:40 AM
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Oh wow! Sorry that you had to learn the lesson the hard way

I am almost done building my first quad. I don't think I am fully up on all quad safety precautions. I read what you wrote, and I don't fully understand what happened-except for the part when you tried catching/protecting yourself from the quad in flight. To me, that was just reflex. I guess if I was out on the flight line and a quad was coming at me, I would put my hands up to protect me too. What I am asking about is what was it that you were testing, and how it is that you could have tested it without endangering yourself like that. Can you generalize the safety "violation" any more, or was this something really specific to what you were doing?
Jun 01, 2014, 07:22 AM
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Hiccup's Avatar
The first NON NEGOTIABLE RULE of doing ANY testing on ANY electric powered RC aircraft is: PROPELLER(S) OFF!!!!

It could have been your eye, wife, or kid (if you have them) which to me is ultimately worse hurting someone else. Bad enough to pay such a high price for our OWN ignorance when we hurt ourselves, but, hurting someone else is un-forgivable!

I would like to personally thank you for being a man and posting this for all to see.
It took a lot of courage!

A very common miss conception of this hobby is that we, "Play with toys". I submit that the inherent danger lurking within this wonderful pastime elevates our hobby to something more akin to Lion taming, because, you never know when its going to turn on you and have you for dinner!!

Glad you are going to heal up! Best wishes.

Hiccup
Jun 01, 2014, 08:21 AM
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JohnnyRobot's Avatar
Quote:
Can you generalize the safety "violation" any more, or was this something really specific to what you were doing?
The specific issue was "What is this LED status code on my Pixhawk FC?"

I was getting a red, blue, green rapid flashing. There was no documentation available to describe what this meant. (ESC calibration mode)

I think it started happening because I changed the air frame configuration from H to X in the software. Perhaps that reversed my throttle? I don't know.

If the message would have been clear, this wouldn't have happened.

If I would've followed safety procedure, this wouldn't have happened.

I really wish that status code would have been in the manual. This could have been avoided.
Last edited by JohnnyRobot; Jun 01, 2014 at 08:47 AM.
Jun 01, 2014, 12:21 PM
multiflite.co.uk
Pretty sure that all flight controllers that have a user interface have a tab called "Receiver" where you can wiggle the sticks and bars move up and down.. if you had gone through that and verified the when all sticks go up/to the right that all the bars go up it would have stopped this..

Sorry that you got hurt this way, always 'props off' whenever doing anything calibration related.. what i do is i have some bricks in my garden that i put on the landing gear poles... was testing receivers for reliability and i'm glad i did because the rx link failed but in a way not to trigger failsafe..
Jun 01, 2014, 01:46 PM
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JohnnyRobot's Avatar
Quote:
Originally Posted by geebles
Pretty sure that all flight controllers that have a user interface have a tab called "Receiver" where you can wiggle the sticks and bars move up and down.. if you had gone through that and verified the when all sticks go up/to the right that all the bars go up it would have stopped this..
That's one more element of the mayhem. The RC direction references were correct.

That's another reason I was caught off guard.
Jun 02, 2014, 11:03 AM
Registered User
Wow, I'm genuinely sorry to learn of your accident but thanks for posting as a reminder that even though multis are "toys" as some call it, they are still dangerous and safety should be a priority.

Speedy recovery my friend!
Jun 03, 2014, 03:42 AM
efx
efx
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efx's Avatar
Wow! Glad to see that you got all your digits. The finger I hurt myself healed, but I still have a bit of a weird sensation on the tip of mine, so I hope you don't have any weird stuff once it's healed. I really couldn't imagine getting that many cuts, that would have not been cool. Even the smallest quad can speed up pretty fast. This is also a good lesson to those who think everyone will be picking up a quad to spy on the world. It takes quite a bit of learning curve as you found out. But it also takes a different type of person to keep learning these things. Anyway, enough of that, I hope you get well soon. Be safe. Also, what size quad was that? It looks small from the picture.
Jun 03, 2014, 10:18 AM
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JohnnyRobot's Avatar
I designed it to be a 550, but I needed to make some changes that resulted in offsetting the motor mounts 10mm. So... It's a 530

Before it went rogue...


Test Flight before 11" props...
Jun 03, 2014, 01:26 PM
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cwrr5's Avatar
WOW! Good on you for posting this up. It's a hard learned lesson, speedy recovery!
Jun 03, 2014, 01:39 PM
Registered User
Wow! That is no fun. Good thing for people like me to read though as I am building my first Multicopter...
Jun 04, 2014, 02:36 PM
Registered User
I'm sorry you had to pay the price to teach me a lesson! I'm new to multicopters and thought all the warnings were to prevent a nasty bump and a bruise or two. You've taught me a whole new level of respect for them. Thanks for taking one for the team!!
Jun 04, 2014, 11:45 PM
Registered User
thanks for posting, i had a similar accident but only 3lacerations in the meaty part of my thumb
Jun 05, 2014, 02:14 PM
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OrbitCowboy's Avatar
Quote:
Originally Posted by Hiccup
I would like to personally thank you for being a man and posting this for all to see.
It took a lot of courage!
My sentiments exactly. This is what makes a community, not just a Q&A board.

Best of healing & fly on!

-- OC
Jun 06, 2014, 01:09 PM
Registered User
Scary! Thanks for posting. I was thinking the other night while balancing my props, just how sharp the plastic props are, spinning at 14,000 rpm, wow.. just wow. My nexus 30 heli had a large rotor which was known to do a lot of damage, but the leading edge was quite dull!

I know the Multiwii has an option to arm with motors stopped or not, after seeing this I'm thinking that is NOT a good idea and if it's armed the props should always be turning slowly. However if you crash into a tree or a bush and can't dis-arm you'll burn out the ESC's. Tough call.. hmm

Ben