Helicopter Default Params

Markus,
I agree it does seem to be redundant. There may be other places in the code that FF_ENABLED alone affects that I haven’t seen.

I flew my Trex 500 today, which doesn’t have a governor in the ESC, with H_RSC_MODE set to 3. I wanted to test this and it actually seems to work quite well. It provides a linear 3-point throttle curve, and works as well for an electric as it does for a gas engine.

My Trex 500 test heli is a heavy (2,750g) modified helicopter with a 1800kV motor running on 4S with a 10A battery, and headspeed 1,900 rpm. I took the DFC head off today and put a flybar head on it. I got better stabilization with the flybar and can run more aggressive PID’s with it. My revised settings are as follows with the flybar:

ATC_ACCEL_P_MAX , 110000.000000
ATC_ACCEL_R_MAX , 110000.000000
ATC_ACCEL_Y_MAX , 27000.000000
ATC_ANGLE_BOOST , 1.000000
ATC_ANG_LIM_TC , 1.000000
ATC_ANG_PIT_P , 4.500000
ATC_ANG_RLL_P , 4.500000
ATC_ANG_YAW_P , 4.500000
ATC_HOVR_ROL_TRM , 300.000000
ATC_PIRO_COMP , 0.000000
ATC_RATE_FF_ENAB , 1.000000
ATC_RAT_PIT_D , 0.000000
ATC_RAT_PIT_FILT , 20.000000
ATC_RAT_PIT_I , 0.120000
ATC_RAT_PIT_ILMI , 0.000000
ATC_RAT_PIT_IMAX , 0.400000
ATC_RAT_PIT_P , 0.065000
ATC_RAT_PIT_VFF , 0.060000
ATC_RAT_RLL_D , 0.000000
ATC_RAT_RLL_FILT , 20.000000
ATC_RAT_RLL_I , 0.150000
ATC_RAT_RLL_ILMI , 0.000000
ATC_RAT_RLL_IMAX , 0.400000
ATC_RAT_RLL_P , 0.055000
ATC_RAT_RLL_VFF , 0.050000
ATC_RAT_YAW_D , 0.001000
ATC_RAT_YAW_FILT , 20.000000
ATC_RAT_YAW_I , 0.100000
ATC_RAT_YAW_ILMI , 0.000000
ATC_RAT_YAW_IMAX , 0.250000
ATC_RAT_YAW_P , 0.380000
ATC_RAT_YAW_VFF , 0.050000
ATC_SLEW_YAW , 1000.000000

I run more aggressive PID’s than the above with my Trex 700 nitro flybar without any oscillation problems. But those settings locked the little 500 in pretty good. I’m not exactly sure what setting H_FLYBAR_MODE to 1 does. Don’t know if it changes the scaling in the rate controller, or what. I tried it with param set to 0 and to 1 and couldn’t tell any difference. Although I only flew it in Stabilize today. I think that might do something for Acro, but I didn’t try that yet.

This is a photo of my new test heli. She’s a heavy beast at 2,750g takeoff weight with that 10A battery slung under there. But it flies for 30 minutes in hover, and is inherently more stable because of the weight. So it’s kind of nice for testing with a heli that’s stable, and trying different things without running out of power in 7-8 minutes.

When H_FLYBAR_MODE is set to one then acro is basically RC helicopter and PID is applied only to Yaw to keep the heading. It is assumed that flybar will do the needed balancing. Obvioulsly this should not be set for Fly Bar Less systems. I do not think that there is any other difference.

Hi Chris,
Can you please post some pictures of the vibration isolation system you use on your Nitro heli.

what is the logic behind keeping it at 75%. While tuning P do we need to keep VFF = 0? Then after tuning set it to 75% of P term?

First of all 75% is not cast in stone, it is just a rule of thumb or a matter of taste.
The VFF is your direct input, it bypasses the PID controller. Please read this pdf
Some pilots fly 700 class and bigger without FB and without FBL-unit etc. , these pilots don’t need/want PID controllers of any kind, this translates into PID=0 and FF=100%. AFAIK nobody is flying a 450 size without FB or FBL-unit. You can fly every helicopter with FF=0 if you have PID>0.

NO, I start tuning by setting FF to have about 75% of the needed cyclic, but you can use the default value as well. This gives me the necessary control (I use Dual Rates and Expo as well) and it allows me to start with low(=maybe not enough) PID values to avoid oscillation drama.

NO, usually you set the cyclic to have about 6° to 8°, The FF should or could be set to give you 4.5° to 6°.

Use the default values, lower ACCEL_Z_P from 0.5 to 0.3( and tune that later) and start the usual tuning process. I use Acro others prefer Stabilize.