Greetings from the Philippines!

I bought my P4 last Feb 2017 and have been loving every flight with it. All my flights have been incident free since I bought it except earlier today.

After my usual preflight checklist (checked and calibrated everything, all systems normal), spooled it up with 9 gps satellites and as soon as it does, the aircraft nearly tipped over to its back. Shut if off by holding the left stick down. I did not apply throttle after arming the motors with CSC.

I shut down the motors and tried again. This time I had 7 to 8 gps satellites. Armed the motors and applied a bit of throttle to take off. Soon as I applied power, the aircraft tilted backwards and hopped/skimmed on the ground a few feet backwards and grazed the street curb with the rear props. At this time, I was able to compensate with pitch forward control and full throttle down to disarm the motors.

After my failed 2nd attempt to take off, I restarted everything (transmitter, aircraft and mobile device). Everything was incident free after that.

Question is... what could have caused this? could it be that I tried taking off with less than 10 gps satellites?

Any piece of information will be highly appreciated as it will help in preventing a recurrence of this incident.

Thank you!

It might but anyway I WON'T fly with less than12 GPS locked, at least... Also what you mean by CALIBRATING EVERYTHING? You should NOT do calibration unless the app ask you to do it. Also don't take off from concrete slab or near metal, etc...

Here's the link to the first flight:

http://www.phantomhelp.com/LogViewer/2AS5Y40QXMLUXTKHIJ99/

Here's the link to the second flight:

http://www.phantomhelp.com/LogViewer/PNVFLH30KZO4K6NR5WCJ/

Thanks

dronist Posted at 2017-4-30 08:22
It might but anyway I WON'T fly with less than12 GPS locked, at least... Also what you mean by CALIBRATING EVERYTHING? You should NOT do calibration unless the app ask you to do it. Also don't take off from concrete slab or near metal, etc...

Thanks for the response. I meant calibrated the compass as I perform this calibration every flight even if the app does not ask me to. And yes, no metal nearby when this happened.... err.... there was an electric post about 8-10ft to my right...

There is no need to calibrate the compass if there's nothing wrong with it.  I never calibrate mine.

Kokok Posted at 2017-4-30 09:18
Thanks for the response. I meant calibrated the compass as I perform this calibration every flight even if the app does not ask me to. And yes, no metal nearby when this happened.... err.... there was an electric post about 8-10ft to my right...

I always lightly punch the throttle a bit on take-off to pop it five feet off the ground. Then I hold, and re-check all systems & settings while it hovers. This allows the bird & me time to re-check ourselves and each other, and "get in the groove".
May have had nothing to do with it but just a couple of feet below the street level are lots of metal pipes electric cables, etc.
I always "pop" and get away from that, then "hover check", prior to departure.

Kokok Posted at 2017-4-30 09:18
Thanks for the response. I meant calibrated the compass as I perform this calibration every flight even if the app does not ask me to. And yes, no metal nearby when this happened.... err.... there was an electric post about 8-10ft to my right...

As Ibuy mentioned below. You never have to calibrate if the APP doesn't tell you to do.
And like Crack mentioned below concrete pavements,  most definetly has metal Rebar in them.
So the more you calibrate the worse it is getting because you are NOT getting  CLEAN CALIBRATION!

What you need to do is find good place to do and IMU calibration ON 100% LEVEL surface away from metal and then do Compass calibration again away from metal. electronic interferences, remove your keys  extra phone/ tablets and that is it.

Do not do anymore calibration of any sort unless asked by the APP.
Good Luck!

It could well be a combination of 'a bit of throttle' & not having a full compliment of satellites for P mode to be effective.

It's worth waiting the few extra seconds for a proper GLONASS/GPS fix. On take off I always use full throttle for a second or two (doesn't give it a chance to perhaps adjust horizontal position and tip over).

As stated above, do not calibrate the compass before even flight.

Once a decent compass calibration has been completed, you only need to redo it, if you travel a couple of hundred miles from the original calibration location.

Constantly calibrating the compass will only lead to trouble, If you happen to do a bad calibration....


RedHotPoker

My question is this: what were the wind conditions at ground level when the motors FIRST spooled up? This happened to me ONCE and I will NEVER launch from the ground again, I always hand launch my drone. I made the mistake once and noticed that the motors kind of give a spike in power on starting up and with the wind it was enough for the front to lift enough that the whole craft flipped over and the battery was ejected and broke a prop. I now hand launch and hand catch on landing. I was advised that rough landings can mess with the gimble...?
Just my $.02 here

Happy flying

I've got close to 300 P4 flights in just over a year..  I've never had a tip over problem.   But I have had a leg come off the ground the odd time at shutdown when the motors somtimes speed up slightly before they stop.

As a side note, I've also never used the auto-takeoff or auto-land in the year I've owned the P4.  I always take off full throttle to gain altitude quickly, hopefully to avoid any mishaps near the ground.   

And..  I can't remember the last time I calibrated the compass

Thank you gents for all the responses. Very helpful indeed and I'll surely be following them the next time I fly.

Question is... should I be concerned that there is something wrong with the aircraft?

Thanks!

I just noticed now in the warnings list on the app that I got this warning on the tip-over flight:

"Compass Interference. Temp Max Altitude: 8m"

Anybody know what this means?