adjusted RC6 and now it operates as it should. Set initial gain on pitch and roll to .04ish. Just wondering should my ATC_RAT_PIT_ILMI be at 0 as well as ATC_RAT_RLL_ILMI mat 0? What is that parameter for exactly? MP does not give a description.
Tim
Spooled it up held down on the ground, no crazy swash movements etc. Everything seemed to react okay? Dunno about vibes as i dont know what im looking for?
Logs above
Tim
I should note only one of those logs is with main blades on spooled up on the ground. One of the other logs was with just tail blades on, i spooled it up and checked for resistance when moving the heli left to right confirming proper gyro compensation.
The tail did not seem to chatter from over gain, although once airborn that may change?
Tim
Tim,
This is all good buildup. Confirming that the tail is resisting movement when disturbed. Unfortunately I donât know how much that can be derived from these logs because as you pointed out all this will change once you are airborne. Itâs best to do some short flights and get your p gain to a point that it feels comfortable to hover. Then we can start scrutinizing the vibrations. Most of the vibe issues Rob was able to pull from Chrisâ logs were found with the aircraft airborne.
Thanks Bill, i guess ill find out tomorrow what its going to do. 
i think tonightâs testing confirmed it wont eat itself at least. One thing i have to do is get the set rpm down a bit on the gov, it was a shot in the dark for an rpm and by the sounds of it i was at around 1600-1700rpm. A bit high i think.
Tim
The vibration levels and IMUâs look good to me for a ground test with it tied down.
Your throttle signal looks a little confusing. You must be using a MODE 1 with a governor in the ESC? With a governor I think I would recommend setting H_RSC_MODE to 2 and set H_RSC_SETPOINT to the value you want sent to the governor. Then simply turn it on and off with a switch. And set the ramp and runup times to make it easier on the drivetrain and what ever it takes so it doesnât cause the heli to spin on the takeoff pad during runup.
A lot of ESCâs have a soft-start for heliâs. But if you have the throttle response set to fast, it will soft-start, then almost instantly go to governed rpm, and cause the heli to twist on the pad before you have enough tail authority to stop it. Thatâs what the ramp and runup params are for.
Thanks for looking Chris! Ill take all the expertise i can get.
As to the govoner, i admittedly havent spent too much time on it. I assigned channel 8 to a switch, brought the endpoint down to 50, the lowest i could go and slaved the throttle hold switch to it for safety. Im using a Castle HV 120 esc with internal gov high running. I like what you are proposing regarding setup and will likely change to that before i fly it tomorrow. What i did worked in a pinch, but as the pwm was still up there it resulted in a pretty hot rpm on the rotor.
The soft start is set to really slow spool up and doesent hand it off for some time, so no tail jerk thankfully, although i will probably play around with the ramp up feature of Pixhawk to get a feel for it.
Thanks again,
Tim
I hate to make recommendations for somebody elseâs heli. But what I would do with a governor is just set a channel 8 switch on/off. Then use something like this for the throttle control
H_RSC_CRITICAL,400
H_RSC_IDLE,0
H_RSC_MODE,2
H_RSC_POWER_HIGH,700
H_RSC_POWER_LOW,200
H_RSC_POWER_NEGC,700
H_RSC_PWM_MAX,2000
H_RSC_PWM_MIN,1000
H_RSC_PWM_REV,1
H_RSC_RAMP_TIME,19
H_RSC_RUNUP_TIME,20
H_RSC_SETPOINT,500
H_RSC_SLEWRATE,0
To explain what the above settings will do:
You arm and throw the throttle switch. The 500 setting for the setpoint is the governor signal at 50% rated power. The ramp time is 19 seconds. So it will take 19 seconds for the signal to ESC to go from 1000pwm to 1500pwm. When the runup time is complete (20 seconds) you are ready to fly.
For a smaller helicopter with less inertial mass in the rotor you can use a faster ramp time. For bigger ones I like to use more ramp time so itâs gentle on the runup and doesnât do anything radical. And it also gives you 20 seconds to observe the heli during spool-up in case it starts to vibrate, shake doesnât sound right, etc. - just flip the throttle switch off and abort it.
Iâm just guessing on the 50% signal (H_RSC_SETPOINT, 500) because it looked like you were using 1500 pwm in the BIN logs on RC8 out.
Now, be aware that some ESC governors will not work below a 70% throttle setting. If you have one of those and the minimum the governor will work at is too fast for the headspeed, then you will have to disable the governor and use a MODE 1 with a mix from the radio, or a MODE 3 with a V-throttle curve set with the H_RSC_POWER params.
Well, not familiar with that particular ESC. Iâm more familiar with piston RevLok and turbine FADEC controllers for Wren turbines. But what I would do is reset the endpoint on your channel 8 switch and use MODE 2. If 50% seemed too fast then try 40% (H_RSC_SETPOINT, 400). Spool it up again with your board and blocks and feed some collective to it to see if the governor actually works. It should hold the headspeed constant no matter what the collective is.
If it doesnât I would definitely fix that before taking it off the board and blocks. Thatâs the safest way to determine if your throttle system is working properly before you actually fly it. If you have to go to a V-throttle curve with MODE 3 you can tune that in the board and blocks too before flying.
Donât want to take off with it running too hot. The hotter you run it beyond what you will normally use for UAV flight, the more responsive the helicopter is going to be. And that can be bad for PID tuning.
Edit:
OK, well. I looked up your ESC instructions. In the Castle Link software it looks like you can set it for a flat throttle curve for Normal, Idleup 1 and Idleup 2. They show a 30% flat curve for Normal with a 30% flat curve set in your radio. So likely a H_RSC_SETPOINT of (40%) would not be too far off for UAV type flight. Then you have enter in the motor info, gearing info, etc., and it looks like you can set the desired headspeed in the Castle Link Software.
You may have to play with that some to get it right. I got an Android phone app I use for some heliâs that I got for like $1.99 off the Play Store. And I got telemetry with mag pickup tachometer on the radio for a couple of other ones. But itâs going to be nice to know however you set up the throttle and governor, that it actually works before you take off.
Chris,
With the Castle gov, i have a few choices. Set rpm, where you tell castle what RPM you want and you assign 3 flat curves of 30-70-90 in your radio and thats it, but thats nore for 3d. Or there is gov high, or gov low depending on what you have for a motor, voltage and what you want rpm you want governed. If i choose gov low i can get it to govern at 1300ish if i remember correctly at 12s, which im thinking is about right? Ill re-set-up the throttle system and give Pixhawk control over the throttle output and just bench test and tach it till i get the result i want.
If i cant get it to govern low enough on 12s, i can always drop down to 5200mah 10s, or 10000mah 6s, whichever works out best i guess?
Either way ill still probably slave the channel 8 switch to throttle hold for double safety, cant hurt anyways. I guess with pixhawk though it seems kind of redundant as i have to not only hit the safety switch, i have to arm it and then flick the channel 8 switch.
Thanks again for the help and ideas,
Tim
Edit: it was definatly governing when i was on the ground as loading the rotor with collective did nothing to slow the disc, the packs took a beating though⌠Dident hit them with the infra red but they were quite warm.
Tim
Yeah, this is what I just saw in the PDF for that ESC. Again, Iâm not familiar with that one but if you can set it for around 1,300 rpm I think youâll be in the right ballpark for your 800 stretch, depending on how much payload you want to lift with it, and how fast you want to fly it without getting RBS. To get flight speeds of 70+ mph with my 700 I have to run 2,100 rpm. On the 600âs I have to run 2,250 - 2,300. But the 700 will fly fine at 900, and the 600âs will fly fine at 1,100.
So you have to use your experience with that to set the headspeed for what you want to use the heli for. And it depends on how the helicopter reacts to LHS. With my one 600, for instance, set up with dual 6S 5,000âs it will tend to tail-bob at 1,800 rpm, and is stable at 1,850 even at 40-50 mph flight speed. You have to use your judgement on what you should run.
One final thing I forgot to mention before is the H_RSC_CRITICAL param. That is the minimum required for flight. Itâs probably going to be around 300 for your setup, depending on how you set that governor in the Castle Link software.
I was running arond 1350 with it using an fbl with my underslung camera gimbal. Its a fair bit of weight added, and if i ran 4 packs i bumped the headspeed up to 1410 if i recall.
Not looking for an incredibly fast platform with this one, just big, stable and able to get some big cameras/lenses/SSD recorders in the air. When i get a chance ill snap a photo of the gimbal i use, its rather large.
Tim
OK, well if youâve flown this one before then just use the same governor setup you were using. And whatever you had for a flat throttle curve in your transmitter, then transfer that to the H_RSC_SETPOINT and it will âjust workâ. The only difference is going to be that Pixhawk controls the throttle instead of the transmitter, and you just enable it with the switch on channel 8.