Futaba GY701 Governor Expert Settings Question

[Graviteesuks]

Hi All,

I have a Futaba GY701 Governor (not using the tail gyro portion because the heli is FBL and I'm using a Microbeast for the tail).

I like to use a fairly low headspeed (1500 rpm) for the "Normal" mode for spool up, takeoffs and landings. I like to switch to 1700 rpm in stunt 1 mode for lazy stunts, then switch to 1900 rpm in stunt mode 2 for 3D. Then I switch back to the normal mode at 1500 rpm for landing. The lower headspeed seems to work better for me during takeoffs and landings. (It's a Raptor 90 nitro)

Since there are 200 rpm difference between each flight mode, the heli wants to kick the tail a bit when I flip the flight mode switch from one to the the other. I'd like to have a smooth transition between flight modes and it looks like there may be a way to do that in the "Expert" menu.

In the expert settings there is a setting for "Revolution Change up Delay" and another for "Revolution Down Delay". There's also a setting for "Start "Up, "Hover" and "Idle Up"
Does this mean that when I flip the switch, the rpm will "slowly" (instead of quickly as it does now) increase or decrease from one flight mode to the next?

If so, which way do I set the numbers? In other words, should I take the value down from the default setting or should I take the value up from default to get the rpm to change slower than normal? (It may say it in the book but I am not seeing an explanation on which way it needs to be adjusted to get the rpm to change or "ramp" up or down slowly). It's on page 76 and 77 in the owner's manual.

Any help from someone who knows how it works would be greatly appreciated!!

Thank you!!!!

[Al Miessner]

Start "Up, "Hover" and "Idle Up"
is the correct adjustment i believe the lower the value the softer the change.

[Graviteesuks]

Originally Posted by tick77

Start "Up, "Hover" and "Idle Up"
is the correct adjustment i believe the lower the value the softer the change.

Thanks for the reply tick,

I believe you're right, it makes sense that the lower the value, the slower or "Softer" the transition between flight modes will be. (I like the term "Softer" better BTW).

I had to install a new clutch liner this evening (The old one was badly worn) so while I was at it I went into the expert settings on the 701 and lowered the values slightly (2 points to start with) for up and down revolutions.

It's WAY too windy to test it (30 mph gusting to 45) but I did try using the low and high throttle limit test in the basic menu and it seems to respond slower than it did before, so we"ll see if that's the case when I fire it up when the wind calms down enough to fly safely. I don't mind 15 to 20 mph but 30 gusting to 45 is too risky for me.

I think I figured out what they mean by changing the values for "Start Up", "Hover" and "Idle Up". The manual mentions to adjust these settings to prevent too lean of a mixture on the carb. If the the throttle is moved very quickly, the carb has to have a lean enough mixture on the idle and mid range mixture valves to handle the quick throttle change, however, if the mixture is set a little richer then you would need to have a softer throttle increase to keep the engine from cutting off.
So, if that's the case, then I can slow the trottle movement down a bit in the expert settings and I can then use a slightly richer mixture at idle and mid range to keep it running a little cooler during those times.
Does that make sense?

Thank you for your help!

[Steve Evans]

Keep an eye on THIS thread. Once I have the gains set correctly with my new 15T pinion for 1680-1700 RPM I'll start tuning the edge rates with the delays, so the use of them will become clear.

I'm using the CGY750, but my findings should apply to the 701 too. I can give a better explanation of some of the settings though.

Rv.UpDly This is like delay on a tail gyro, a larger value softening the increase in throttle. Once I have the gains set correctly I'll be adjusting this to minimise overshoot when switching from, say 2500 to 2700 RPM as a step change (by going from idleup1 to idleup2).

Rv.DnDly The same, but for decreases in throttle. You can see the effect that this will be used to tune out below with these Dly values as minimum. When switching from 2700 to 2500 RPM you can see that there is an overshoot. This is because there's no engine braking on the electric motor and it is slower to respond. I clearly need to increase Rv.DnDly here.



StartDly A bit of a mystery that seems to affect initial spool up speed and lock. I'll be analysing this further.

LLmt_Hov The minimum throttle applied below 2000rpm.

LLmtIdup The minimum throttle applied above 2000rpm.

Also note that LimitSet Idle and High are used to set the extremes of servo travel used when in gov mode, but these do not apply when not in gov mode.

Steve

[Graviteesuks]

Hi Steve,

According to the graph you supplied, it's not as stable as I thouht it might be. Of course yours is with an electric motor and ESC instead of an nitro engine which I read can be a fair amount trickier to set up and I'm sure you'll be able to get everything balanced out with the gains and other values as you go.

I had reduced the Rev Up Delay and the Rev Down delay by two numbers from the default settings, 8 for up and 10 for down is the default settings, I set the first one at 6 and the other at 8 but when I flew it yesterday, it didn't have "much" effect and it seemed to change quicker than it did at the default settings so I took it back to the default settings until I can get a better understanding of how it works, so, your reply has given me the chance to understand how it works a little better.

I'll keep an eye on your progress as you post it.

Thank you! This is the kind of info I like to see!

Note: I haven't been using any type of logger to keep track of PID loops, inputs and outputs, etc. but on mine (with an nitro engine), it's pretty easy to just listen for changes and I can see the changes visually as well. So far the worst part is when I quickly unload the disk as in a tail slide, I notice an over rev but not too bad. I'd rather use the optimze mode for different constant headspeeds with the flight mode switch than to use the rev limit mode and a throttle curve.

BTW, I noticed that you are using a throttle curve in the optimize mode. Shouldn't you be using the "Fixed" mode for an electric setup instead of "Optimize"? It says in the manual to use "Fixed" mode for electric and setup a throttle curve. Maybe you could try using the "Tx Curve" mode and set it up for "Rev Limit"? (Just a thought).

Thanks for the technical data! It helps to understand it and I look forward to further results from your tests.

Thanks again!

[Steve Evans]

Hi,

There are mixed comments on the web about which THR.Mode to use. Tx.Curve or Optimize will allow the use of feed forward if needed. Experimentation will prove which works well.

I agree that you can hear instability when it's bad, but seeing it plotted like this is a revelation!

Steve

[Graviteesuks]

Originally Posted by Steve Evans

Hi,

There are mixed comments on the web about which THR.Mode to use. Tx.Curve or Optimize will allow the use of feed forward if needed. Experimentation will prove which works well.

I agree that you can hear instability when it's bad, but seeing it plotted like this is a revelation!

Steve

Oh, Ok. I didn't know you could use a mixture of different modes like that. Cool! :-)

I totally agree that seeing hard data in a graph is not only a better way to tell what's going on beyond what you can see and hear but it's just plain cool! :-D

I love to hookup my oscilloscope to a circuit or even a gyro output to see and record exactly what's happening if there's a problem. I had a tail gyro a while back that was making the servo jitter and it turns out that the gyro had a very wide rise and fall on the output (more than 30us) and it would spike at times on the rise of the signal. The control receiver had very nice clean square waves with less than 3us on both rise and fall so it was a bad gyro.