Okay, so Saturday afternoon I had a little mishap with my Phantom 4.  I know what went wrong, but I want to see if you guys can guess what went wrong.

Here's what happened.  After quickly putting my Phantom together, I was sitting at a table with my controller and I-pad to my right.  The Phantom was sitting on the concrete surrounding a swimming pool to my left some distance away, somewhat close to some furniture and pool, but not dangerously so.  With the drone turned on, the controller running, and DJI Go 4 active, I got the green ready-to-fly signal, tapped the takeoff icon, and swiped the screen sideways to take off.  At the sound of the motors revving up, I turned to watch the drone take off.  Before I could even get my head turned, I heard a distinctive THUNK of plastic on concrete, followed by total silence.  The Phantom was upside down on the concrete facing the opposite direction, its battery beside it.  As I stood up to rush over, something white splashed down into the pool and sank.  The drone was intact and completely undamaged, except for a propeller that was at this point sitting at the bottom of the pool.

Thankfully, I was able to recover the propeller, dry it off, and put it and the battery back on the drone.  I thoroughly inspected it for damage, and after finding none, I flew a test flight just to check for any other problems, this time taking off from the grass well away from the concrete, furniture, or water.  I quickly realized what had gone wrong.

Just for kicks, can any of you guess what went wrong?

I would say moving to quick and didn't lock one prop.

certainly look like prop not locked in!

First guess is that a prop was not locked, however I also wandered did you have a home point displayed and a good GPS lock and no compass problem?  I had my P4P flip once off a box  onto it's props, reason unknown, Saturday I seen a Phantom 1 flip over on takeoff also reason unknown  it happened in the blink of an eye.

It looks like the propellers didn't lock well. You are lucky to find the issue timely.

Battery was not securely in place, and promptly fell out on attempted takeoff
The prop came off due to the resulting accident and upturn

Aloha Wolf,

     Looks to me like most of the commenters understand your accident.  The reason I think so is due to the prop taking off without the Phantom and later landing in the pool.  Some of the other peripheral suggestions also have merit.  But, only Genghis notes the battery issue.  In his case, I would reverse his priority though.  I think the prop came off first and then the loose fitted battery came out on crashing.  

     BTW, the battery issue could be a blessing.  Some crashes have been due to the batteries not being securely in place.  It is a good practice to double check the battery installation by trying to pull it out after installing it.

     If my theory is correct, the prop came off of one of the rear arms and the tip or outside surface of that arm's motor or motor housing will have a noticeable abrasion from the crash since it landed on the concrete deck of the pool. The impact of the arm tip dislodged the battery.  Or not!  All in fun!  Mahalo for the challenge though.  Got to keep my gray gray cells working!

Aloha and Drone On!

Well, who wins the big prize?  Wolf

worst. quiz. ever.

It is obvious your drone was being taken down by a patriot missle and that is what caused your propeller to come off, resulting in.the crash.

Could it be the re-rod in the concrete which is made of malibu iron which can be maginetic and cause interference with compass...

fansb1fe1104 Posted at 2017-9-20 14:53
It is obvious your drone was being taken down by a patriot missle and that is what caused your propeller to come off, resulting in.the crash.

We have a winner.

ALABAMA Posted at 2017-9-20 04:15
Well, who wins the big prize?  Wolf

Well, I hope you all can split the prize.  I don't know if the battery was loose or not, but it was clear my left rear prop came off once the motor started up.  Thankfully, except for the top of the propeller hubs, there wasn't a scratch on the drone.

The moral here is make absolutely certain the props are locked into place before flying.

We'll split the $million equally then.  Next time, give us a much harder one .  We do love a challenge!