Jinxed myself

[crash1sttime]

After saying in this threadhow i was having a fault free flying experience, I went and had a flyaway today.

It started with a trip to Abney hall in Cheadle, the weather was nice, no wind, some sunshine and I wanted to get some aerial shots of the hall itself, I always take my laptop with me and when i first turned on the phantom i did an advanced IMU calibration as it was required, i did all the other relevant things to ensure a safe flight.

However when take off time came the app told me i was in a restricted area and would be limited to 10.5 metres, this was due to me being near the airport but i could live with the height restriction.

On take off i had 6 sats, as soon as i got 20ft off the ground i looked at the App and i realised i had lost sats and as such i landed straight away.

I moved to the front of the hall and my sat count rose up so i took the bird up to about 60ft and took some nice aerial view of the hall itself, with confidence high i proceeded to fly around the grounds, i did notice that if i dropped to low height the sat count dropped but if i stayed up high it was ok.

Once finished with the front of the hall I moved round the far side, being in a new area I did a compass dance and took off flying, my sat count was 10 at this point and i had a really good fly round even getting a shot of some planes coming in to the airport, although no where near enough to cause any harm may i add.

As my battery dropped to about 27% i decided it was time to land and I flew the bird back towards me, at about 20ft out and 20ft up i started to descend, with the nose away from me i moved the stick back to get the bird to come toward me when ...


BAM...the craft did a smart 180 degree turn and at speed shot passed me, rather suprised to have an out of control bird I quickly remembered the things i had read and flipped the S1 switch to middle postion to get ATTI control, but there wasnt time and the poor little thing ran into a spread of trees about 40ft away behind me.

As it hit the trees i felt sick to the stomach as i watched and heard the tortured scream of blades on unforgiving wood, again i reacted by doing a CSC command to shut down the craft and ran over to the wounded craft.

Heres the pictures

Damage: one of the props has snapped on the tip (bottom picture, bottom right blade), Dirt had pushed in through the camera air vent, this was easy to remove once the camera was opened up other wise just general dirt on the body. oh and one of the rubber feet had worked loose from the gimbal

I dont know how or why it should just go beserk, it just did, it may have been interference from the airport, ive never flown in that area before and i wont be again.

Should i scrap the other 3 props ? they seem to be in an ok condition. Im now nervous about taking it out again in case it happens again.

 

[paulajayne]

Change all the props £20 compared to the cost a drop from a greater height.

Full checkout required I think, lid off and check connections - change the cam belt and top up the oil as well while you are in there.

Full recalibration as well.
Ps Check motors for debris and blow out with an air line.

 

[crash1sttime]

ive done a recalibration and I have spare props, luckily i got 3 sets with the phantom when i bought it, ive not considered taking the lid off, do you really think that i should ?


Have been having a think about this since it happened, and my theory is that i have RTH on low battery activated and that the battery level had dropped to the point where it was about to kick into RTH mode and somehow as i was pulling back on the stick it decided to elevate itself under power which caused it to come shooting back towards me. just a theory as i said

 

[paulajayne]

Just might be worth checking plugs and connections to ESCs.

Easy to do.

 

[Milkman128]

RTH low level battery screwed me once. I was done with my flight returning to the LZ (which was under some trees) about 10 seconds from committing the landing and I hear the wizz of my props winding up full speed. I looked at my phone and it had the RTH low battery pop up. By the time i hit cancel it had collided with the tree branches above. I have since turned that "feature" off and plan not to use it unless I'm doing an extravagant long flight. Camera popped off a wire to it frayed. all 4 props were damaged but only 2 catastrophically. The rubber dampeners all fell off and the battery popped out.


Luckily the bird still flies. I think there is some damage to the camera but I need to test fly it in day light before I'll know for sure. It had some weird lighting affects at times in the video but the night lighting was also weird.

 

[crash1sttime]

Have read here recalibrating compass when in same locale causes issues sometimes .

Glad you mentioned that, i thought the CD was needed even if you only moved a few feet from where you last flew, to be fair to myself i was just being cautious

Glad it didn't get totaled bro

Im hoping that it hasnt, but not had a chance to fly yet.

Im going to open it up now

 

[crash1sttime]

Yep ive opened her up and cant see anything loose or not right, ive also moved the GPS cable whilst i had it open.

Well i only have to fly it now, im feeling kinda nervous but if others have had similar hard landings and still fly then it makes me feel more confident

Thanks to all those that replied

 

[kengineer]

I would first like to say I do not know what happened, then ask do you think it is possible that it hit the Return To Home (RTH) trigger from a low battery and thought it was returning? In other words, did it think that returning to home involved a flight path thru the object it hit?

Is this just a case of a good Phantom trying to do the right thing?

Did it know where home (or the home you wanted) was? Did you set the RTH position?

If I do that with mine, I will open it up to have a look, I want to see what the mythical GPS puck looks like anyway.

 

[crash1sttime]

Hi

Im thinking, and bear in mind it happened so fast, that i was pulling back on the right stick to bring it back to me, and the RTH on low battery auto function triggered, which would mean it then tried to power up to go to the 90ft i've set as a RTH altitude, this meant that it suddenly flew at speed backwards instead of upwards.

In all im guessing it was just bad luck, i wasnt looking at the app at the time so may very well have missed the RTH message with the option to cancel, its the first time ive taken the battery as low as i did, and something i wont be doing again, although i have now disabled the RTH on low battery option.

I want to see what the mythical GPS puck looks like anyway.

Its just a square of ceramic with a GPS module stuck in the middle and a cable, and its under a sticky pad. sorry to spoil your fun

 

[Happyflyer]

crash1sttime,
Hope you get your quad all cleaned up and running once again.
.
milkman128,
That sudden RTH pop up can open your eyes when it happens. My one time it happened I was lucky, no trees. Sure was a surprise as I was landing at the time and all of a sudden, UP!

 

[Meta4]

Sounds like you have a handle on what caused your crash. Having your Phantom act on its own can be disconcerting especially if there are obstacles in the way. A good reason to turn that feature off.

the app told me i was in a restricted area and would be limited to 10.5 metres .. sat count rose up so i took the bird up to about 60ft i did notice that if i dropped to low height the sat count dropped but if i stayed up high it was ok.

Not sure what happened to the 10m limit but it's not a factor.
You always get better sat reception up high where your horizon isn't obstructed.

being in a new area I did a compass dance and took off flying

You can safely travel 50 miles or more (sometimes much more) without affecting your calibration at all. If you have a good calibration, keep it unless you change or crash your machine or travel long distance.

 

[crash1sttime]

well lessons learned as they say, the craft has been cleaned up, the table spoon of mud that was jammed in the camera air vent has been removed and ive opened it up checked all connections, done all the calibrations as neeeded. All i need now is better weather to test fly it.

 

[crash1sttime]

Ok so today i took the bird out for its test flight, the wind was blowing a little bit

Did an IMU calibration before hand and also did the RC calibration as well. Did the compass dance as well.

On take off the craft rose up ok to about 20ft or so but then seemed to start acting hinky, now with the wind being a bit blowy, and having only flown on really calm days im hoping it was that that was the cause, you see it didnt seem to want to hover in the one spot and seemed that instead of the steady droning noise, I could hear it making a noise that suggested it was compensating, again im assuming the wind will cause that.

It did i suppose behave normally enough, it didnt wander to much from home point however when coming down to land i hovered about 1.5ft above the floor and it seemed to rise up to about 4ft, at this point i bottled it and decided to land.

I cant see any marks on the craft to suggest twisting of the arms and the unit sits level if turned upside down, so im really hoping im just being a bit paranoid and that the windy weather was causing the slightly strange behaviour.

 

[Great Pumpkin]

however when coming down to land i hovered about 1.5ft above the floor and it seemed to rise up to about 4ft, at this point i bottled it and decided to land.

The rise you experienced is normal because as you bring it down, it will encounter and be buffeted by its own prop wash rebounding from the ground. Just stay with it and bring it down slowly through the prop wash, and it will land gently.