Flight Stability not consistant

[Geoelectro]

As some may remember I flew my P2V into a lake about a month ago. Replaced the lost battery and camera. Since installed a RP gimbal. Since the lake incident I have been questioning whether my P2V is flying as good as it used to. It seems to have trouble staying in one place. Especially when turning.

The first flight with the RP was in a strong wind so I attributed any drift to the wind. The following morning in fairly calm conditions I took off from my driveway to about 6 feet and it kept wanting to climb. Also it drifted around. I kept it down and kept correcting its position and it finally seemed to settle down. The video of both flights look good due to the RP.

High winds kept it grounded this weekend but this morning I took it up again. It was somewhat erratic and kept wanting to come down. I kept pushing it back up to around 10 feet. I took it up to 70 feet to fly over some trees. I pointed the camera down and was looking at the trees when suddenly it started to spin around. I fought it to keep it near having trouble determining its orientation. I finally got it back down barely keeping it from crashing into a tree.

So, I showed it had 10 sats. It always seems to follow my stick inputs. It seems however to have trouble staying in one place and recently with altitude. BTW after only a few minutes this morning into the flight the battery was showing 68%. By the time I landed it it was close to 50%. I just plugged it into the assistant software and it shows 53% and balanced.

I'm going to open it up tonight and check what I can see. Seems like the GPS is working and reporting number of sats. It is staying level making me think the IMU is OK. I suppose a flaky motor or ESC could cause the same symptom. Any ideas?

Geo

 

[thedjiguy]

Calibrate the compass and calibrate the IMU. It couldn't hurt.

 

[Geoelectro]

When I put the P2V back together from the lake incident, I noticed the screws had a thread lock on them. In my business we commonly use thread lock. I decided to apply some to the screws during re-assembly. Not the red hard lock but the blue.

This evening as I started to dis-assemble for inspection I was startled to find cracks in the shell, especially around the screws. Apparently, the thread lock damaged the plastic. The shell seemed structurally sound but frankly there was a significant amount of damage from the chemical. I don't know if this was in any way associated with the problem it has staying put in the air, but I suppose it may. Otherwise, I can see no other damage from the lake. I have a new shell on order. I will clean and secure all plugin connections, calibrate and try again.

Geo

 

[gunslinger]

When I put the P2V back together from the lake incident, I noticed the screws had a thread lock on them. In my business we commonly use thread lock. I decided to apply some to the screws during re-assembly. Not the red hard lock but the blue.

This evening as I started to dis-assemble for inspection I was startled to find cracks in the shell, especially around the screws. Apparently, the thread lock damaged the plastic. The shell seemed structurally sound but frankly there was a significant amount of damage from the chemical. I don't know if this was in any way associated with the problem it has staying put in the air, but I suppose it may. Otherwise, I can see no other damage from the lake. I have a new shell on order. I will clean and secure all plugin connections, calibrate and try again.

Geo

There was a thread about this issue not that long ago, but I haven't been able to locate it yet. When I do, I'll pass it on. I was pretty surprised in reading in that thread that loc-tite and similar chemicals could chew through the plastic...

-slinger

 

[Geoelectro]

The first time I cleaned it up from the lake incident I never opened the GPS area under the top. It has a self adhesive cover or pad over it. I wondered if that sould have been looked at. I opened it today since I'm replacing the shell and sure enough there is a plug on that board that goes to the compass. It would make sense that a faulty connection to the compass could cause the instability I've been seeing. All connectors now cleaned and waiting on the new shell. Fingers crossed!

Geo

 

[EMCSQUAR]

Still perform an advanced calibration, then do stick calibration then finnish up with compass calibration. Also check every electrical contact point for corrosion any little resistance could cause a hiccup at an ESC or motor.

 

[Geoelectro]

Still perform an advanced calibration, then do stick calibration then finnish up with compass calibration. Also check every electrical contact point for corrosion any little resistance could cause a hiccup at an ESC or motor.

Good advise! I'm on it.

Geo

 

[Geoelectro]

Yesterday I got my new shell. Transferred everything over and calibrated. Did the compass dance. Took off and it continued to ascend without me telling it to. I had to fight to keep it close. It was not stable at all. Realizing it was likely going to crash I pushed it toward a small tree hoping to keep it from the pavement. It hit the tree and fell upside down on the grass...twitching. Powered it down and noticed a prop missing. When I located it nearby, the motor was still attached. At least half of it. Looks like the C-clip came off during the crash and the motor separated. Otherwise, no visible damage except two props.

So, I suspect there may be an electronic problem internally. There are several major assemblies, GPS, Control Board, NAZA etc.
If I decided to change one of these out which one would you go after?

It powers up properly, acquires satellites, All motors spin and it flies. It seems to have problems with altitude and locking into position. It does follow stick inputs. Since it was under water I suspect any of these assemblies could have been damaged. From the symptoms, I'm leaning to the NAZA or GPS assembly. Any thoughts? Any other tests that would reveal where the problem is?

I sure want to fix it so I can fly with my new Rotorpixal gimbal!! :?

Geo

 

[Lukevia]

HI Geoelectro,

Did you ever determine the cause of the erratic flights you were having? After a recent crash, I've got everything back up and running (new shell, motors and props). I've followed similar steps and it now doesn't want to hover very well.

I'm curious if you determine the cause in your case.

Thanks!

 

[Geoelectro]

No, not for certain. I found a replacement craft for a little more than what I was planning to spend on replacement parts. That said, I believe it's the NAZA module which sells for $230.00. I was going to replace that plus all four motors. That comes to $350.00. I found a craft from a dealer that is tested for $499.00.

I want to get back in the air right now so back burner on the old craft. I may swap NAZA's as a test on the older craft in the future. The only other suspect part is the compass. I figured a cable kit at $10 to $12 plus the compass at around $15 would round out the repair. Remember, in my case it was not a crash but under water.

Geo

 

[jimdenburg]

I don't know if this has any bearing on your issue, but you mentioned it may be a NAZA problem. I do recall reading on a couple of different forums about removing the NAZA and pounding it on a table to fix an issue with it? Might be worth a shot if you're looking at replacing it anyways, plus the "hit it" or "pound it on the table" methods are by far my favorite types of fixes

 

[Geoelectro]

UPDATE:
My replacement Phantom (craft only) came in on Monday. We have had nothing but rain and wind since. This morning, sun is out and completely calm. I nervously took the new P2V with RP Gimbal out for a test. I had already done the IMU cal and did the compass cal right before takeoff. My last couple of flights were so bad with the P2 climbing, turning and pitching a fit all by itself I was simply afraid to take off. I want to take it to the country this weekend and I'm leaving this afternoon so I have to know if it flies and if I should take it.

I took off and it was perfect! the most stable I've seen since my first one was new which was never the same after the lake incident. The contrast between that and now is unbelievable! I just looked at the short video and with the calm conditions and the gimbal this is the most stable video I've ever seen from the P2V.

I am packing it up to go to the country! Yeah!

Geo