Hello there, this is Dipanjan. Been trying to be airborne for a while, so finally bought all the basic stuffs to get started, I started with a plane, but failed at the first attempt, however at the second attempt I was able to fly.
There is nothing more interesting is this world than Copters and 3D printers, right? So I decided to build a Tricopter (as I wanted to get a long flight time). I had initially bought 3 X Emax MT 2213 motors, a Radio, and a 3S 3Ah Turnigy lipo. Then it came to the flight controller ,and I decided to make a multiwii for myself, initial tests were very positive and I decided to give it a go.
So today I went to the ground for testing out my tricopter. Charged the battery, connected it, and YES, IT FLIES !!!!


Now as I landed it,a  little boy came running and said "propeller ure gelo to"(The propeller has flown off). To my surprise I found him to be correct, then the hunt for propeller began, we went through bushes to find the propeller in perfect condition. So far so good,but where has the propeller adapter gone? It was nowhere to be found, and I thought I would fix it using some other nuts. So,went to a cycle repairing shop, then to my second surprise I found that the one I have lost is the CCW one, that's not easy to find. Cool enoguh, isn't it? OK,so I came back home,had to discharge the lipo to storage voltage ~3.8V per cell, so turned the rest motors on, and as the battery voltage came below 3.82V, I took the lipo out of the fibreglass pouch it stays in.
HERE comes the most surprising thing,
to my surprise I found the lipo bent  !!!!!!!!!!!!!!!!!!!!
it wasn't warm ,the motors had ran perefectly in my hands, but the lipo was bent. The shrinkwrap got shrinked in some places. I was too afraid that it might catch fire,and put the lipo inside a steel tiffin box with four small holes in the top of the box (Steel has higher melting point than Lipo fire). A friend of mine said that the loose propeller might have hit the lipo, causing the bend.

So here are the two questions I want to ask-
1. Where to find a replacement Nut? I believe it is a M6 nut ,but anti-clockwise threaded
2. Is it safe to use the lipo? I am going to watch it for 2 weeks,if it still holds the charge,then shall I use it?

last but not the least- am I the only one so unfortunate today?

here is the video of the Tricopter

Here are some pics of the bag and the LiPo.

It feels very bad,as this was a fresh Lipo, just charged today for the very first time. I can feel by hand that there is no crease in the lipo cells, Don't know if I should use them, just checked now after 5 hours, cell voltages haven't dropped at all. They are now at 3.82-3.83-3.82 ,just where I had left them.

Man, these Lipos are scary.

why do you feel they are scary ?

ignore the hype surrounding them and use your own observation. if a short was to happen it
would have happened by now.

they will not spontaneously combust.

if it smells funny then be careful , otherwise use it.

So far as we have seen only puffing is a problem. I have some Lipos which look like they are bent or maybe they really are. But it's all normal. I store them in a steel box / safe inside my house and nothing untoward has happened in over a year. Always check voltage before and after using them, thats all.

Please discontinue the use of any puffed or such battery as it might catch fire
Get a new lipo. That battery is not worth your or anybody's life

You had a prop fly away in flight , and I am surprised that you didnt crash!!

Did the prop came loose while landing ? Asking because a tricopter can never fly with out a missing prop !

However , from the pictures you posted what I understand is , the way you mounted the lipo to tri is a problem , you should mount it in a flat surface with velcro ties or tapes or anything.

That bent can't be happened without a force , tell me the truth , haven't you crashed??

@ Saikat ,the lipo is in perfect order, no puffing, no funny smell, no voltage loss, it's the videos of lipo bursting into flames,that have made me worried.
@starquadcoters, I though I was the only one storing them in steel boxes
@Darshan, thanks a lot for your kind concern Darshan

@Sooraj , I myself didn't notice when the prop flew off. Actually this is the very last video, and after the touch down (as in the video), I found the prop missing. It must have flown off exactly when the copter landed. I didn't crash it. That's why I was so surprised to find the lipo bent like that.

What about the prop adapter? I have asked hobby shops, but they have said it will take at least a month to get those nuts. Meanwhile I have made my own nuts, will test them soon.

Should there be any nuts or protruding item in the place you mounted your lipo? As mentioned above, tricopter has a bad tendency to have no forgiving capacity and a little loose prop will come while taking off!. Is the flown off prop is from the yaw arm?  The lipo looks fine, no need to worry, a lipo with any cell opened or has a short is dangerous.

@ Dipanjan , if its only one ccw prop adapter that you need , I think I can help you with it , let me see whether I have anubspares lying around.

Thanks a lot Sooraj, I really appreciate your concern. Checked the lipo today,still no sign of voltage drop, still they read 3.82 - 3.82  - 3.82. I would need only the nut. Please let me know if you have a spare.
Warm regards,
DIpanjan

Check the diameter of the prop adapter. Normal nuts did not fit my SunnySky motors either but M5 locknuts from Indian.Hobby.Shop did. Check here You should always replace stock prop nuts with nylock nuts since they are far less likely to fly off.

Have ccw  nut, it fits emax 2213 motors . pm your address i will ship it.

Well,maybe Sooraj has been busy in his life, didn't get any reply from him. Will try to get in touch once he comes online again. Well to solve the issue temporarily I made my own nut from MSeal,and it works till now. When hardened it becomes rock solid,and there it is,you can see in the video the white nut,that's the one I made. After the flight it came loose,but I have tightened it again. here is the video of the tri

https://www.youtube.com/watch?v=WN2PSOB8geM&feature=youtu.be

Man,I thought they would be very easy to fly. Phew. The main concern is the spectators around,I cant even turn it safely. Don't know how to overcome that. I haven't done any PID tuning even. What does the video show? Does it need PID tuning?

Good news is that the Lipo is in perfect condition.