Throttle mix in Gov mode

[Helicentrik]

When using the esc in gov mode do you need to inhibit throttle mix.

[BarracudaHockey]

While I have no direct experience with using throttle mixes with electrics in governor mode, thinking it through, if your throttle curve point sets your rpm with the governor mode being resposible for adding or removing power to maintain rpm, I would say that the mix would change your throttle point thereby changing the commanded RPM, not helping maintain it like it does with a nitro machine or non-governor mode.

I would inhibit it

[Helicentrik]

Am I right is saying that the governer stops the head going above a set HS. Does the governer also command more throttle to maintain that HS. (Sorry did not read your reply properly yes it does add power. In that case I would inhibit T mix.)

[Trnquill]

Originally Posted by Helicentrik

Am I right is saying that the governer stops the head going above a set HS. Does the governer also command more throttle to maintain that HS.

In theory gov does whatever it needs to do to maintain a set headspeed. It will increase or decrease power output as needed. That's why one should use no more than ~85% of max power when using gov. This allows the logic to push some more juice to motor during demanding maneuvers.

On nitro or gas engines there are govs and limiters. Gov works similarly to a gov in an ESC, limiter only limits max rpm. A limiter can be used almost like a gov by setting the limit RPM a little under the no-load RPM of an unlimited system.

[Helicentrik]

I,ll try it when I'm out next. I suppose in a way using throttle mix is the same as using a governer but not as accurate at maintaining HS, and throttle mix won't stop the head running faster. Is the governer mode more popular.

[ollie2893]

No, no mixing at all for gov mode on EP helicopters !! Just fly a flat TC, somewhere below 90% - depending on HS desired (and dampers fitted).

This means, very roughly speaking, that the ESC will only feed 90% of the voltage available at the start of the flight to the motor. But it will try to hold that voltage throughout the flight. Basically, your max governor input (eg those 90%) should not be higher than the voltage remaining at the end as % of the voltage at the start of the flight. Only then can this work (since the governor is no miracle power generator).

NP pilots who fly governors will sometimes need to consider mixing the tail and governor target. That is because their governors pick up the actual HS relative to a frame-mounted Hall sensor. During very high-speed pirouettes, then, the HS reading becomes affected by the body spin and a governor adjustment may be required. This is not necessary on EP because the ESC actually reads the motor shaft revs.

[Helicentrik]

Thanks Ollie. What compound on the dampers. I'm assuming hard.

[ollie2893]

I fly the grey (soft) dampers because I like my 2D HS at only 1500 rpm (500W hover draw) and the black (hard) dampers would induce a bob below 1700 rpm.

[Helicentrik]

I suppose this is where I have to start experimenting with different setups. It's good to have all the info up front. I'm using the KBDD medium dampers at the moment I'll se how they go. Also I'm using a Futaba 12FG do I need to activate the governer in the TX or is everything handled by the ESC.

[ollie2893]

Well, congratulations, that's one fine radio. Yet you shall find, it's totally over-spec'ed for modern-day RC modelling where much of the processing that used to take place in the Tx now takes place on-board the model, be it inside the Rx, the governor or the FBL computers. So forget all about your 7-point TC. You will need to set all 7 points the same because, indeed, the ESC does it all for you.

[BarracudaHockey]

Originally Posted by ollie2893

This means, very roughly speaking, that the ESC will only feed 90% of the voltage available at the start of the flight to the motor. But it will try to hold that voltage throughout the flight. Basically, your max governor input (eg those 90%) should not be higher than the voltage remaining at the end as % of the voltage at the start of the flight. Only then can this work (since the governor is no miracle power generator).

Thats not really how it works.

An ESC is a high speed switch. At WOT (wide open throttle) its on 100 percent of the time. At 50 percent throttle its pulsing on and off with on 50 percent of the time and off 50 percent of the time. At 3/4 throttle its on 75 percent of the time and off 25 percent. At the times when its ON, its at 100 percent power.

[Helicentrik]

Thanks I understand now.

[ollie2893]

Originally Posted by BarracudaHockey

An ESC is a high speed switch. At WOT (wide open throttle) its on 100 percent of the time. At 50 percent throttle its pulsing on and off with on 50 percent of the time and off 50 percent of the time.

Sure ... and the net upshot of all this switching is ... that at 90% throttle you get approx 90% of available battery voltage during time interval t. During that interval power was 100% for 90% of the time, and zero for the rest.

The point is that the governor will extend the "on time" as voltage falls off(coz of decay or coz the IR forces the eff V down during high A draw). However, since it cannot generate power, it cannot extend the "on time" beyond 100%. If 100% of whatever voltage prevails is less than eg 90% at the start of the session, then HS will drop even though you are flying gov mode. Such is life.

My recommendation therefore stands. Set your gov% of the starting voltage of the pack no higher than the equivalent of 100% of the finishing voltage of your pack. Then you should see constant HS throughout. Better still, allow some extra% for headroom. Align recommends no higher than 85%.