I picked up some generic white props on Amazon.com, the other day and now my bird is flying very erratically, not able to hold a position, twitching in the air and even wanting to ascend without any input on the stick. (landing is inherently difficult, as you could imagine).

I've done advanced IMU and compass calibrations (in spite of the 'over-temp' warning in the IMU section) and the conditions persist.   I have a set of OEM phantom 2 props on their way, but is this really a possibility? Can props screw with this thing that badly?

absolutely,

most generic are severely unbalanced and that can cause all kinds of crazy flights.

you can google prop balancer to try and fix


good luck and have fun flying!

kirk2579@aol.co Posted at 2016-1-24 23:33
absolutely,

most generic are severely unbalanced and that can cause all kinds of crazy flights.

I don't think it's a balance issue because my video is perfectly clear (no jello).
I'd just read about issues with the Carbon Fiber blades being more prone to vortex ring effect and I thought maybe these generic blades were suffering some sort of similar symptom... but it doesn't appear to be a balance issue.
It's odd... I'll take off and if I let it hover, it will randomly pitch to one side, or the other...  it almost looks epileptic, as though it's getting some odd gyro readings.   As I've said, I've calibrated the IMU, both basic, and advanced. The numbers all look w/in range, based on what I've researched, and they don't appear to jump around in the Assistant software..   They do seem to change readings by hundredths, as I sit there and watch the display, but I assume that's normal, as it is incredibly sensitive equipment, and even the slightest HVAC current could be jostling the chassis, not even perceptible to the naked eye...  I'm making assumptions here.

Props that are screwy usually show signs of vibration and some erratic behavior but not as you have described. I would double check that IMU calibration to be sure it was good. If it's not hovering stable and acts strange sounds like calibration more that out of balance poor props. A double check is worth the time.

Sadly, I've checked, calibrated, double checked, and recalibrated. All numbers SEEM to be in check.   I did, recently, have an impact where my low battery signaled RTH and the drone immediately flew into a pole, but it wasn't a rough impact.   It chewed a couple props as it bounced off the pole a couple of times and hit the ground from about 12'.   
That's how I ended up with these aftermarket props.    Could I have knocked the IMU loose? Is that a thing that happens?

could have knocked a few things loose for sure, you may want to open her up and have a look if the numbers look good otherwise and the new props do not help...

Check all your values against here as a general reference...

My readings are pretty close. I'll pop it back apart and take a look.
Another odd symptom.. sometimes at power-up, I get the flashing yellow tail lights until GPS lock, then the green strobe, then the flashing green.   Other times, I get one yellow, one red on the tail lights and when I get gps lock, the Yellow flashing turns to slow green flashing and the red just goes out.
it sounds like I need to pop it back apart and look for more loose connections.

dj_brady@email. Posted at 2016-1-25 07:24
I don't think it's a balance issue because my video is perfectly clear (no jello).
I'd just read  ...

the gimbal will stop shaking in video,

if you did the IMU and compass and all ok then it is your props causing issue !
do not under estimate a bad prop set.
when all is said and done ask what is different now vs when it flew well....  props!

some times it is the simple thing.

buy your props from some where like B&H not amazon.

I have bought "genuine DJI " props from amazon and end up with generic in fake package. be careful!

dj_brady@email. Posted at 2016-1-25 20:29
My readings are pretty close. I'll pop it back apart and take a look.
Another odd symptom.. sometime ...

just one thread of many!

http://www.phantompilots.com/thr ... .65818/#post-649700

roy@mcscomputer Posted at 2016-1-25 17:18
Props that are screwy usually show signs of vibration and some erratic behavior but not as you have  ...

not always so simple .
this is but one example of bad props

http://www.phantompilots.com/thr ... .65818/#post-649700

Good to know. That's the first thread I'd seen about wonky flight based on bad props.. maybe my search terms were wrong, but I was unable to find any anecdotal evidence relating props and flight issues. Thanks very much for posting that for me.

That said.. I did pop the case back off and started searching for issues with my tail lights displaying oddly (left rear red, right rear yellow OR left rear out, right rear green) and determined I've got a cold solder break in my ESC on the left rear.  if I apply pressure inverse the screw holes (press up on the ends instead of down), the lights function normally... the left rear goes back to red (or out, depending on whether or not I have sat lock) when I apply downward pressure on the ends of the ESC.   I powered the motors up and they didn't seem to spin any differently depending on pressure, but who knows what's happening during flight.
Looks like I'm going to order and replace one ESC.