Gremlin Accelerometer issue

[Fireflyer]

I recently built a gremlin . I have flown it a about 5 times no issues no suddenly it created a roll right that i can't trim out must hold extreme back left until until the right roll increases enough that the gremlin can't be controlled . I have not had any major crashes to cause damage . I have been on the forum trying to trouble shoot this but can't seem to get it to go away.

I have:

Checked and reset all TX/rx in beta flight All center stick are all at 1500

re-calibrated the accelerometer

I went to the motor tab and ran each motor to recheck rotation and isolate vibration

checked that the FC is secure in the frame and not moving

tightened the air frame to eliminate vibrations.

I shut off the accelerometer and pow! flies with a nearly hand off hover

I can also fly in atti mode which does not use the accelerometer.

I am currently flying stock settings on PID , tuning would be done in rate mode I'm not sure this would correct my issue.
Any suggestions would be appreciated.

 

[ElectriSean]

In Betaflight, does the model image move properly when you move the FC around?

 

[Fireflyer]

Yes It moves correctly in beta flight . No drifting on the module/receiver page either .

 

[Fireflyer]

I'm going to take the FC off the frame and replace the mounting tape this is the only thing I have not tried in regards to the physical aspects of the Gremlin . Is anyone else having the same experience with the accelerometer?

 

[PsyBorg]

I would try to reflash it. There have been some strange behaviors and set up issues with these lately. In most cases reflashing betaflight has fixed it. BTW its not only the Femto and Gremlins. Its Beta flight being testy. One even stumped Joshua Bardwell on a live troubleshooting he recently did. The problem that guy had was all axis worked except throttle.

 

[Fireflyer]

OK Thanks . I did have some trouble flashing the Femto at first and my Throttle was a little bit of trouble setting up . I'll give it a try and see how it goes.

 

[Fireflyer]

Well, no luck . I setup a new model in my transmitter and remounted the FC with a single piece of double tape. Flashed the FC three times

1st flash was the current version of Betaflight / SPRACINGF3EVO (SPEV) 3.2.3 Dec 11 2017 / 08:03:17 then test flight same failure

2nd attempt was the prior version Betaflight / SPRACINGF3EVO (SPEV) 3.2.2 failed

3rd back to Betaflight / SPRACINGF3EVO (SPEV) 3.2.3 Dec 11 2017

All attempts resulted in an increasing right roll and forward pitch. This increases until uncontrollable , and cannot be trimmed out. I can still shut the accelerometer down and hover nearly hands off . I have zero vibration and zero movement in all tabs on beta flight . Any other suggestions ?

I did notice a balance issue in the transmitter DX9 spectrum does not return to center by +6 on the roll balance I have programmed it out of the TX rechecked it after reversing the roll control . My RX/TX is at zero and rock solid even in beta flight .

I'm stumped on this one , is there anything else i can try ?

 

[Fireflyer]

Is this maybe just a FC failure ? I would order an new FC if I thought it would fix the issue but if it's know in newer versions i don't wish to repeat the problem.

Has anyone use alternate FC for the FT gremlin?

 

[PsyBorg]

With that comment about the radio having a lean and you not seeing any change with reflashing but STILL having the lean I would say its the radio not the FC with the issues at this point. Do you have anything else RC you can try using that radio? even a car or truck would show a pull if a servo was plugged into the roll or rudder channel.

 

[Fireflyer]

Tried other models,and helicopter and even another transmitter no issue.Seems to be isolated to the gremlin.

 

[PsyBorg]

Well that has trouble shot your issue to a bad accelerometer on the board. If it flys fine in acro then it is still usable. This is common with the Femtos specifically on seriously hard crashes. Sometimes on not so hard crashes. After all it is an extremely sensitive piece of equipment. I the Gremlin flys with out it fine roll with it. you are far better off flying in acro mode anyways even when flying inside. Auto level modes make one lazy and teach bad flying habits anyways as its a battle of you Vs the accelerometers to fly not you vs the environment and aircraft.

If you have control issues as far as too wobbly and quick you can always lower the rates and form your own Expo curve how you want to make it very docile. The rates I am using on my Gremlin are seriously soft in the first half of stick range and quite aggressive at full deflection. You are more then welcome to put those in and try them. Just ignore the pids as they more then likely will not be good for your Gremlin.

 

[Fireflyer]

OK well I'll give the rates a try . I fly my heli with very aggressive rates, the gremlin handles fine without the accelerometer I was just enjoying the ability to pass the transmitter to the kids with the ability to self level. I ordered another gremlin hopefully it won't develop the same problem. Now just waiting on some warm weather to get out and rip it up a bit .Thanks for the help PsyBorg

 

[PsyBorg]

Oh don't worry about the kids mate. They will learn faster then we ever could. Specially if they have had ANY experience with console based video games. You just need to keep them from flying like its a video game and making crashing a new hobby unto itself hehe.