Big 30Kg turbine heli tuning AC4.1.1

Baro issue during runup:

blue plot is rpm
red/green is baro 1 and 2
yellow is baro alt

On this heli, we arm, and after we launch rsc. Turbine take time to take it’s RPM, as rpm goes up, barometer see presure drop.
Issue, is that heli see 15m alt…while it’s always on the ground.

Ideal will be that RSC calibrate zero baro press alt at the end of rsc runup time…

If anyone know solution to help us…

I would post this on the arducopter topic as it would get a wider audience. Just start a thread with this post and a good title. In most cases I have seen altitude drop during lift off when increasing collective. Not sure if I have ever seen it increase like that during spool up. Looked at one of my logs and it shows a very small increase during spool up around 0.5 meters. And then on liftoff, it shows the altitude drop 2.5 to 3 meters.

What is the blade collective pitch when you are spoiling up. I wonder if the turbine is causing an issue when you are spoiling up

Whaoo yes I think is turbine aspiration increasing in the canopy that make de depression on the canopy, blades are on zero trust point at -1deg during spoolup

Thank you heri, this can help us to reduce slow oscillation but what about the YAW IMBALANCE message? As showed with little wind during slow flight curve we touch saturation point at 0,33% and is what is set on rat yaw Imax param. This value is marked on the tradheli wiki tuning guide… with ilmi to zero

Question is it can be dangerous to set rat yaw imax to 0,6 with ilmi zero… ? can we set ilmi to 0,33 and imax to 0,6 to ensure that at slow speed and take off i not increase over 0,33?

Does ilmi work on yaw?

I use ChrisOlsons parameter for my 700 to 800 class helis. These are i = 0.11
ilmi = 0 and imax 0.5 and vff = 0.
Than i tune with the wiki.

Works for me.



Maybe this. "yaw imbalance" - how to troubleshoot? - #6 by bnsgeyer
solve your question

Hello, finally we put specific antivibration system on the heli,
Now we have quite good signals (fft before filter):
You will find here the dataflashlogs:

we remade all VFF and PID process, now the UAV is perfect.

But we have strange behavior in LOITER…
When static loiter, many times we have woble within 50cm…
and I see on the log this that I cannot explain:

In dynamic flight desired PSC target acc trend to match target acc…
But when “static”, desired PSC.DA acc = “zero” but taget continue oscilating, and the UAV follow this oscilating requests…
PSC controler is not tuned and set with standard values…
regarding the same moment, we see on PIDN currious phasing:

does any body has experienced this? and can help to resolve this issue?

Hello Bill, today I make flight with heli.
Finaly i get back psc controler param to standard and i get good loiter results pushing stab p roll pitch to 8.
I read on the wiki to dont go over 8, can you confirm that? Im pretty sur that pushing little bit over 8 i will reach perfect loiter.
Can i test that?

I have pushed the Stab P parameters to 10. At some point you may see feedback oscillations due to this. If you do then you just have to reduce the gain.

@bnsgeyer Hello Bill, I always read your posts to learn.

So, one question, what is the complet name of this parameter “Stab P”?

Thank you



@heri Stab P is the same as ATC_ANG_XXX_P.

Hello, I have the same question for stab yaw.
I tuned rat p and d to max without oscillations, but I cannot get off the slow oscillations 0,5hz ±3deg on the yaw axle…

Stab yaw p is set to 4.5 can I try to increase it to 8 with ch6 tune to expect get off this oscillations ?

Hello Bill, thank you for your answer. Following your posts helps me a lot learning how FC
works for trad heli.



Hello, I have the same question for stab yaw.
I tuned rat p and d to max without oscillations, but I cannot get off the slow oscillations ±3deg on the yaw axle…

Stab yaw p is set to 4.5 can I try to increase it to 8 with ch6 tune?

Envoyé de mon iPhone

Have you ever tried to contact Chris Olson? He is a Pro in big turbine Heli tuning.
For a fee he will set you up with a perfect flying turbine Heli, I believe.

Your turbine helicopter sounds very interesting. If possible please post a picture of the helicopter.

@kuspower I see that you are using an external governor, and the effect is very good. Can you tell me what kind of governor you are using?

Governor for the tail rotor?

Thank you :wink: i will post photo

Governor for the engine