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Trex 600 stretched (700) Pixhawk 3DR tuning

I calibrate it outside, before I mount it in the heli

the offsets X:120, Y:45, Z:22

is that 120 is high?

I can take it out of the heli and re calibrate it if its not good .

Thank you

Someone correct me if I’m wrong but you should do the calibration while it is installed in the helicopter. It needs to be able to characterize your mag field produced by the helicopter so that it knows how to calculate the true magnetic heading.

I will calibrate the heli whiteout taking the FC out today maybe I can get better offsets numbers

But my question is; do I need to do that every-time I change the location of the FC?

I know that FC’s GPS is disable and the external GPS is the one active, so I don’t need to calibrate Compass every time I change the location .

But the gyro maybe effected since the location of the FC change !!

But I think as long as heading to the front and no change in the direction then we should not need to calibrate it either!

Thank you

If I were you since you are learning, I would redo all calibrations every time you move the FC. It doesn’t hurt anything to redo things. Cutting corners is not something you should be doing since you are constantly having trouble. Helicopters in general are not something you can be lazy or sloppy with.

I totally agree!
Trust me without your guys, I can’t go one more step !!

You are a big help !
I will recalibrate it…

Just want to ask about your heli,
I know you use gasser heli and the gasser helis have more vibration than electric

How you control that vibration ?

I also see you use electric helis too

How you mount, where and what do you use to damp the vibration ?

It will be really helpful to me and others want to learn how to deal with this ghost ( vibration )

Maybe you use different components in the heli ?
I replaced everything in the heli and still have vibration !!!

Edit ;
Can you please if you don’t mind post pics of the good vibration level and the (Rate P and R) so I know what a good vibration level is, and what a good RATE att P and att R are good to compare with daily tuning?

Low frequency oscillation and high frequency

I appreciate your inputs

You missed some settings when you transferred to the Pixhawk 2.1.


Your altitude looks good. I would say you can make these changes. Fly in stabilize to make sure it feel ok. By the way what did you think of the lower Accel and higher input_tc values.

After you fly in stabilize then you can try loiter.

Oh yeah I forget those changes

I will change them and fly it with Stab and loiter

After lowering the Accel and higher input_tc value the heli was better but still fast respond touchy little bit.

If I was not experienced pilot, new pilots may get lost with the direction when it turn in front of the pilot ! And since it’s sensitive to the inputs; will end with crash …

Thank you


after changing the values;

I flew the heli and it was good.
I don’t know if the vibration is still there?

I replaced the double side tape to the one that comes with the Pixhawk (3m thick hard foam )

I really had a hard time to calibrate the compass ;(

I tried over 25 times outside home, same locations I used to calibrate my old pixhawk

but this one refuse to give me a good result!
best I could get using the QGC is on the beginning of the green bar!
and I didn’t like it because the X: 420 something like over 400 as I remember !

and I re-calibrated the compass thinking things will get better, but now the best is on the yellow bar and most of the time on red!

its just frustrating! I know there is interfere but with what?
everything is aluminum even the compass cable I warped with aluminum tape! and away from anything!
just the metal screws that hold the mast and the little screw holding the round aluminum plate that the GPS set on it!

maybe the screws! but what I will have to use if I need to remove them! and why the old pixhawk GPS was super easy to calibrate and I had low offsets numbers!

please correct me if I am wrong…

thank you for all the time you spending with me to make it happen!


sep-14-2019.param (14.1 KB)

Did you try doing the compass cal using the relaxed fitness setting instead of the default. I find that I have to do this more often than not to get a good compass cal.

Where to find that setting ?

I am still having problem with calibration

Thank you

Read this wiki on Compass Calibration. Read the section on onboard calibration where it talks about if the calibration fails.

Thank you Bill for the link!
I switched to Relaxed setting, but I was not able to get a good calibration, so I switched back to default and calibrated inside the home and got lower offsets numbers… don’t know if I need to get it more lower!

I think I can try to calibrate it at the flying site! maybe I can get lower than 100

but I tested the loiter mode; so when I had a higher Compass numbers the heli was doing toilet bowel in a big area! not good at all.

but when I re-calibrated the compass and got the new lower offsets numbers, I flew it and was much much better and nice steady ! it was not staying holding its position like Drone, it was moving slow within few inches

maybe within 1 Sqf … and mostly on the pitch axis (tipping down and up) like bird eating :blush:

I also replaced the new shaft with another brand new one, also replaced all bearing blocks’ bearings and lubricate all bearings, re tracked the blades and greased the red gears to give smoother run!

what do you think if we tryi out the ALT hold or other modes maybe Auto?

thank you


I re-calibrated the compass outside and get much better reading!!

here is pic of the calibration results (offsets)

I see no bird eating here heheheh :slight_smile:

hope this time is getting me better !!

Thank you

I’m surprised that your mag cal had that effect on your loiter performance. I think you can start doing some high speed flying in stabilize, ALTHOLD and LOITER. Just build up in speed and if you see anything suspicious slow down and pull the logs so we can look at it. If your flight at high speed is good then you can move to AUTO missions.

I appreciate your help Bill!

I have a video recorded the loiter flight

Please look at it and see what do you think ?

Thanks again

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Looks good to me. I think you are ready to move on to forward flight.

Boy you fly in a very confined space. You are very trusting of these systems. If you had any type of failure that caused you to lose control of the aircraft, you’d have no where to go. You really need to consider what could happen and take precautions to protect yourself. I’ve done some testing of some experimental rotor configurations and I’ve placed trees between me and the helicopter. Even with my reliable helicopters, I still have a bigger area where I can get away from the aircraft if there is some type of failure. Please be more careful.

Agreed, very very dangerous. Especially with all those walls around you in loiter mode. The GPS signal can be getting multipathing causing jumps in measured position.

Somebody in my hometown was killed by a model helicopter slightly smaller than this. You cannot ever feel this comfortable around a helicopter while in flight. Everyone needs a healthy fear of them.

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Your guys right! I never did that till the recent build,
I am a member of a realy nice flying club and we have big runway.

Its becaue tnere is a lot of tests and so many changes, was unable to go to the flying site 5 times aday between my work.

I had somw work during the day and I had to stay wake overnight to test flight the system!

But yes, I am going back to the club this week:)

Just wanted to ask queastion;
Do your guys like the old pixhawk 1 (3dr pix4) better than the new 2.1 one and why?

I am lookinng to buy another one for my other orange costum made heli, but I run through a good deal; sombody want to sale me 2 new pixhawk 1 (3dr pix4) for $100

So I was wendering if there is a reson behind choosing the old one over the new one …

Thank you so much!

That looks really dangerous.

It is very dangerous,
But I always fly and there is something between me and the heli, like Columns, big tree or I stand behind the door…

Incase if something happen will hit the walls and fail down…

I had one accident 15 years a go at the flying site, was flying hard 3D cross the runway and on blades came of about 50 feet hit the car window !!

So sometime it’s even more dangerous in the flying club than behind wall since there are more people around! Specially if the flying club is closed not open !
But anyway thank you for the comment

Servers by jDrones