12kg quad, first flight and tune

Hi everyone!

I’m getting ready to conduct my maiden flight of a 12kg MTOW quad.

I’m using a cube orange, two HERE 3, Herelink, TF02 pro lidar, T-motor MN605-S standard arm set on 6s lipo (Alpha 60A LV ESC).

I’m planning on flying 2-3 10000mah 6s lipo.
Propeller size is 22 inch.

To everyone out there who has some more experience regarding setup and tuning of these mid size to large multirotor. Do you have any advice or something that’s easy to miss before the first flight?

I’m planning on doing a first flight to try and get some hover throttle values. Than go on and tune my filters. I know I have to enable the fft but there was some other mask parameter to chose between logging filtered or un filtered values, right?

Parameterfile: Before first flight

https://drive.google.com/file/d/1vMPL_OJ39p9MPIVUaZ6UH8bnY8EjNMc3/view?usp=sharing

Thanks!

Set this back to 0 to collect pre-filter data at a rate that’s useful, all else looks good for a 1st flight:
INS_LOG_BAT_OPT

Thanks!

I’ll be setting the logging settings for the flight!

would there be any issue to fly with a takeoff weight of 5kg for the testflight when my MTOW is 12 kg, maybe 14 if I push it.

To see if it basically fly’s I suppose not but not sure you will learn much else.

I would set
BATT_FS_CRT_ACT,1
BATT_FS_LOW_ACT,2
FENCE_ENABLE,1
INS_LOG_BAT_MASK,7 (get all the IMUs)

If the ESCs are separate to the motors and motor mounts use:
MOT_THST_EXPO,0.76 (dont use the low 0.2 for Flame ESCs, which is likely wrong anyway)
If the ESCs are built into the motor mounts use:
MOT_THST_EXPO,0.4

As a curious guy… why do you change thrust expo in these situations?

The Flame ESCs may or may not do something funky with the thrust curve - it’s hard to nail down.

The Alpha ESCs probably dont do anything strange with the thrust curve when they are (purchased) seperate from the motors, in this case use the calculated MOT_THST_EXPO

The T-Motor combo units (motor and ESC combined in one arm-mounted unit) seem to be an Alpha ESC and some independant thrust stand tests have shown them to be MOT_THST_EXPO = 0.4 and this is probably a safe bet.

Once you get flying you can always adjust MOT_THST_EXPO based on:

  • set too high you can see instability at low throttle
  • set too low you can see instability at high throttle
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I’m not sure what you mean, sorry. English is not my native language. Maybe my question was poorly written.

My maximu takeoff weight is 12kg

For my first flight I intend to fly lighter, at 5kg.

Would this make my copter overpowered? since it almost has 3 times as much thrust as weight?

Sure I’ll do!

My alpha ESCs are matched with my motor so It should have an expo of 0.4, some uses 0.2 with success as well.

Thanks!

Sure it would. I simply mean that there would be no point in tuning anything at that weight as most tunable parameters will change when it’s at it’s typical flying weight.

Ah, my bad.

The lowest weight I plan on flying when In use is around 8kg. If I get the payload to 8kg. I should tune it for 8, than adapt my accel parameters right? To be able to fly 8-12kg.

Or is 8-12 too big of a difference, and I would need to chose a more exact weight to tune for?

Yes, that’s right. That’s a fairly large range to cover but if that’s what you need that’s the process.

I’ll try to make the difference smaller, I could put on an extra battery for the minimum payload scenario. That would add like 1.5kg

FYI, mass is not the only thing that matters when it comes in tuning the controller.

Moments of inertia are crucial also, i.e. the way that this extra mass (payload) is distributed around on the copter’s frame.

My batteries are mounted on top of my frame, as you can see on the picture in the initial post, the batteries are located quite close to the FC inside of the sandwich designed frame.

The battery payload will change along with the bottom mounted payload. The bottom mounted will most of the time be a 3 axis camera gimbal the size of a gremsy t3. So the bottom payload might be affecting the CG a lot since it will be hanging a little bit further down from the frame.

Maybe it would be a good idee to tune the frame with some light payload on. Than it won’t be such a big difference to go up and down a bit in payload weight as if it would to go from no payload to maximum payload weight

Nice, thanks for the clarifications @xfacta!