Helicopter Rotor Speed Governor

ArduCopter Traditional Helicopter
81

The SPH engines with bevel gearbox are popular. But so are the SPT engines with a planetary box and horizontal output shaft, driving oil-bath hypoid gear transmissions instead of plastic gears.

Vario’s design, for instance, uses the SPT engine, but with open crown-gear style plastic gear transmission. Once you get into the commercial grade UAV helicopters with turbine power, they use oil-bath hypoid gear and the plastic gears are scrapped.

82

Nice!
Plastic gears also make a special sound…

83

Well, they do. But the problem is torque with the bigger UAV engines. The plastic gears can’t take 40-50 shp from the larger engines.

84

I can imagine that…
Stripping the tooth is indeed a risk, but I guess the smaller sizes can get away with cheaper plastic gears

85

Interesting stuff these larger UAV’s

Must be nice working on these

86

The parts are bigger so you can use real wrenches, prybars and hammers. But so is the cost of operation. You are looking at in the range of $500-550/hr to fly a 700lb turbine UAV helicopter, not a lot different from manned. Cheaper than a 206B Jet Ranger, which is around $1,200/hr. But more expensive than a manned Cabri G2, which is around $330/hr.

Airbus helicopters has an unmanned version of the Cabri G2 with a JetA-burning turbocharged piston diesel in it. With 100LL avgas being phased out it would be a nice alternative, vs gas piston power, to the high operating cost of turbine engines.

87

Hello,

Did you manage to make it work?
The RPM reading is -1 all the time.

Thank you
Rotem

88

What rpm sensor are you using? We have had reports of the futaba GV-1 rpm sensors not working. Still trying to figure out why. Here is the most recent thread.

89

Hello Bill,
I’m using the Align RPM sensor like the one that Chris recommended.

I’ve connected a servo tester to the AUX5 and I can see RPM reading so I believe that my setup is correct.

Thank you
Rotem

90

I’m cross-posting here, since I’m not sure which of these threads is being monitored, and the use of the speed sensor is probably more common in helicopters.

I have also been bitten by this bug, but with an aerospire sensor. I wrote some new governor code for Copter 4.1, but when I went to test it, I get no rpm signal at all (testing on Copter 4.0.5). Reverting the firmware to Copter 3.6.12, the same sensor works fine.

I am using a Drotek Pixhawk3 Pro, not sure what controllers others are having problems with. But it doesn’t appear that the issue is limited to the Futaba sensor.

91

Hi, everyone,
My governor seems to stay disengage…
I have a hall effect RPM sensor on AUX1. I see 2300RPM on data screen and log, while I set it to 2000RPM in GOV_SETPOINT.
I think it follow the throttle curve (set to 80%) rather than the gov setpoint…
It’s a 450 size heli with 3500KV and 13t pinion 2 blades FBL head.
helico450 copter 4.0.7.param (30.5 KB) .

92

Couple problems;
Whether it is electric, piston or turbine, the throttle curve should set so it can fly the helicopter and maintain a relatively constant rotor speed using RSC_MODE = 3 before using the governor. While your helicopter would fly the way you have the throttle curve set, it would run at extremely high speed.

H_RSC_THRCRV_0 80
|H_RSC_THRCRV_100 80
H_RSC_THRCRV_25 80
H_RSC_THRCRV_50 80
H_RSC_THRCRV_75 80

Second problem, the droop setting is not high enough to actually do anything. So it will just over-run and follow the throttle curve instead. At only 10% droop response the governor won’t have enough output to adjust the speed.

H_RSC_GOV_DROOP 10

Since the governor output is pretty much shut off at 10% it over-runs and faults and the governor is not even on - it defaults to the throttle curve.

93

Thanks Chris
Unfortunately, it’s not that…
I’ve changed throttle curve to 80% all points, and gov droop to 90 then 100. Same result.
rotor run to 2500RPM while setpoint is 2000RPM.

94

In fact, the speed run up to 2400RPM (almost 80%, the throttle curve) and when taking off, under load of positive pitch, fall down too 2000RPM, but with a bad regulation, running high, low, high, low quickly.
I’ve test with a 50% droop, 75% and 90%, it’s the same.

95

send you new parameters I’ve change in H_RSC:

helico450 copter 4.0.7.param (18.4 KB)
[URL=https://www.casimages.com/i/210309023207216372.jpg.html][/URL]
[URL=https://www.casimages.com/i/210309023207497704.jpg.html][/URL]

96

Could you post a log of a flight? It is impossible to diagnose from the param file.

97

Great work, great thread. I’m building a 700 size electric helicopter, and the governor comes in handy as I a have a non-governator 90A ESC in store, and a Hall sensor is lot cheaper than a new 90A governor-mode ESC :slight_smile:

Now I just need to work out if I can find out how to feed the RPM signal to an Omnibus F4 controller or if I have to use a Pixhawk…

98

The OmnibusF4 PRO has 8 PWM outputs…you can convert the highest numbered one (its a solder pad on the board) to a GPIO for use as RPM input by setting BRD_PWM_COUNT to 7 instead of 8…

you will need either 5 or 6 PWM outputs (depending on swash setup) for throttle,tail servo, and swash…
if only using 5, then setting BRD_PWM_COUNT to 5 would set output6 (thru-hole) to GPIOs use as well as the higher outputs

99

Hello Chris,

Can you please help with this issue? The Heli is changing head speed like it’s trying to keep the governor set point and then it just fallback to the THR curve.

What am I doing wrong?

Thank you very much
Rotem