Trex250 setup and tuning

Hey guys,

I have some knowledge from arducopter projects but heli mechanics, as well as tradheli code is new to me.
So feel free to comment :slight_smile:

Frame: used Trex250
Motor and Servos are stock
ESC: Some Hobbywing BLHeli ESC flashed with Heli Code (not _S, and not _32), so with governor.
FC: Matek F405 Wing
Telemetry: Holybro 433 Mhz V3
GPS: standard M8N with compass
Code: 3.6.5, stock params with adapted values for servos and swash…

Weight with Battery: 430gr

The tail has a lot of play. In fact around half of the overall travel…

Remembering my first steps with the copter code years ago, I was very confident in crashing that thing on the first occasion. That is the reason, why I started with a cheap and used frame…

Some impressions from the first flight:

Tune yaw first, says the wiki:
Do you see hope, or should I buy new parts immediately?
What does the constant offset mean?

We see an offset with DesR larger than Roll: So CG or swash is not level. I will have a look into that.

Same, but also VFF can be decreased a little bit?

Better then expected (!), looked more at live vibration levels than at the flying heli during that flight.
FC mounting is quite good, main and tail blades are junk…

Did not cover it yet, very funny result. (As long as you will not switch to AltHold…)

I am pretty shocked, that it flew so well…

I’m no expert and I’m trying to learn as well, but thanks to the forums here, I was informed that increasing your roll and pitch ILMI values a little bit helps with the roll and pitch offset issues (experienced the same thing on my heli).

there is a lot of deviation in the yaw. So if you are seeing a lot of slop in the linkage then I would recommend removing the slop. Let’s see how the response improves once you fix the tail.

In tuning the pitch and roll axes, you’ll want to look at the rates not the attitudes. this is the RATE message. I believe you will use for the roll axis RATE.R and RATE.Rdes and for pitch RATE.P and RATE.Pdes. Make sure that the actual and desired rates are of similar magnitude for sharp inputs. You will adjust VFF based on this. the wiki describes this in more detail.

Only after you get the VFF, P and D gains adjusted, will you start adjusting the I gain and the ILMI and IMAX parameters. As Chris indicated, ILMI will help close the gap between the desired and actual attitude.

these look a little high. Did you balance the rotor system? Did you track your blades? Poor track and balance will contribute to high vibrations. You definitely want these below 30 in flight. We typically shoot for 5-10 for heli’s. Less than 5 in flight is REALLY good. the reason I am saying “in flight” is that heli’s typically have worse vibrations when on the ground expecially if you have a high amount of negative collective pitch on the blades.

Great to hear you had a safe first flight!! that was the goal of the initial parameter recommendations.