Need some technical opinions...

Jtrjr · May 14, 2017

Hey guys. Got the Hellbender back in the air yesterday. Replaced the flight controller. The problem I'm going to describe was present before I smashed the bird the first time and broke a chip on the original FC so I know it's not an issue with the FC since it has been replaced. I have to believe it's either a motor or an ESC. The ESC's are brand new and as part of the troubleshooting process of this problem they've been reflashed and recalibrated. The motors are also new but I'm suspicious that they may be knockoffs. I say this because they were packaged one each in a brown box and the CF motor wrench that I use on my other EMAX motors won't seem to fit these.

So here's what happens. Overall the bird flies fine but when I go to do a fast left turn (yaw) the bird seems to dip. It only does it on a left turn, not a right. Also, at one point I went to do a straight up, level punchout, the bird dipped severely on the left side. I'm attaching a video clip showing what it's doing. The first clip is the punchout and then I did the punchout again in slo-mo. The middle of the video is examples of the issue and a couple of rolls. The last clip is one of the most extreme examples of the problem and then repeated in slo-mo.

I have to believe its either an ESC or motor but want to try to determine where the best place to start might be. Replace an ESC, which one? Replace a motor, again, which one? Replace the ESC and motor together, which one?

Any thoughts or opinions would be greatly appreciated.

Jerry

theGreenOrange · May 14, 2017

Looks like front left motor to me. Might be front left ESC but I would probably swap the motor first. Swap with one of the right hand side ones if you don't have a spare and see if the dip changes sides.

theGreenOrange · May 14, 2017

Let me know how it turns out, I was having a similar issue with my Predator. I am waiting on a new motor and FC in the mail.

QuantumQuadsFPV · May 15, 2017

Take off the props put it into betaflight and go to motors, click the switch "I have the props off", and spin up all the motors at the same time via "master" slider, theoretically all motors should spin about the same rpm give or take a few. Find the bad motor or esc. To determine which is which take motor 4 and switch it with motor 1. If the newly switched motor that is now in place 4 spins bad than it is the esc, but if the newly switched motor that is now in place 1 spins bad than it is a bad motor.

QuantumQuadsFPV · May 15, 2017

Theoretically all motors should spin at the same rpm, if they all work perfectly.

"To determine which is which" I meant "to determine if it is either the motor or esc"

Jtrjr · May 15, 2017

Green,

I was thinking the left rear but I guess it could be either. It doesn't do it every time.

Quantum,

It's worth a shot but it's an intermittent issue and doesn't happen every time. I'll give it a try though. Great thought, thanks for your input.

Jerry

Jtrjr · May 18, 2017

Okay, the HellBender appears to be back in the air. I did as Quantum suggested and tried to determine fault by spinning up the motors in BetaFlight. They all ran okay but they left front sounded a bit different than the others. I do think they're knock-off motors because none of them sounded great. Anyway, replaced the left front motor with another and just did a real quick test flight and a few punchouts and it seemed to be fine. Will have to wait for the weather to change before I'll get a change to really test it. Thanks for the suggestions and input guys!

Jerry

Update: 05/21/17 - Got to fly a few packs and got more agressive with my flying and it appears that the issue still exists. Will be replacing the ESC next.

theGreenOrange · May 22, 2017

Jerry, if the ESC doesn't do the trick, I am wondering if it just doesn't need more P? The FC that was doing it to me is toast, so I will let you know if it goes away on the new one.