Head gain, tail gain (cyclic gain in tail tap

[sctholson]

Well now that I have the ability to adjust gains in flight, all I can say is holy crap that saves time. The rotary knobs on the Graupner MZ-18 have detents that are 4-5 steps at a time, so it's not perfect, but it's awesome.

The head gain turned up until I saw too much elevator bobble from a jab, then turned it down. Transferred the number to the Cyclic tab and locked it.

The tail gain was the biggest eye opener. I had never needed to run the gain very high, but on 720BE with 4.0 firmware the final setting was 80%. It would have taken me 5 flights to dial that in. Anyway, it's also set now in the tail tab and locked.

I've got the knob now set to the Gov gain and I'm working on that. I need to see the logs to know how accurate that current setting is.

Anyway, for the question, I noticed that at 80% tail gain the tail holds very well in punch outs and reverse punches (up and then down). However when the heli is doing a cyclic intensive maneuver the tail blows out. Is this the Cyclic mix on the Tail tab?

The last flight log and set up file attached.

Thx

[georgi UK]

=] Scott, there is no throttle channel shown in the log, so I take it you were in RPM 2? the rpm is holding well although the gov is working fairly hard to give you this. it could be you need to increase the overdrive and play with the gov gain some more? the idea being to get a flatter gov output.

for the tail I imagine it's gain is set too high which is detrimental to the limits it can handle? so please try reducing it, and see.

it looks like the cyclic servo ball positions need to be longer, get nearer to 60% swash mix. that' s about it!



example of a smooth gov as the pack depletes =

[sctholson]

Georgi, was that example of a heli in a hover? I hope so, cause I'm not gaining on it.

Here are five flight logs (gee I'm sorry there are five - over the top?). I have governor gains from 25 - 47, Each flight log is named with the gov gain used. All other settings were the same, I've included a set up file too. Again the only difference in these flights is the gov gain.

When you looked at the previous log I had the overdrive at 20 and I've doubled it to 40 and a tail gain of 80 and I lowered that 5 to 75. For the purposes of this test I did not change either of these again. Perhaps that should be my next variable.

Also, I did not change the ball positions yet. Once step at a time.

Oh and just remembered in the highest gov setting 47 I did not have any discernible tail shake, however the tail did not hold in a left-handed nose down funnel.

[georgi UK]

=] Scott, from what I remember the log contained inverted gps rescues, def not a hover flight!

yes, 5 logs, Eeek! like you say nothing is improving, so the Q has to be = is the pinion correct? for the overdrive I was more thinking 100....

[sctholson]

Hi Georgi, thanks.

I'll give the overdrive of 100 a try, perhaps a little more information.

Scorpion HKIII-4035-500kv
HW 120A timing set to 18.75 and pwm of 12
RPM of 1700
12 cell
Main gear 128
Pinion 13

should translate to 75% of capacity at this voltage. Perhaps the batteries are sagging? timing or pwm changess?

[georgi UK]

=] Scott, I think a 12t pinion would be better for those rpm's, do you have one?

[sctholson]

no 12t pinion.

I was running at 1700 for flight time, but it doesn't look like the best set up. I can try raising the rpms to see if it effects the headspeed performance.

Using Mr. Mel's calculator, I should be somewhere up in the 2000 rpm range?

If I don't like flying at that headspeed, I will have to see if I can get a different kv motor and pinion combo.

[georgi UK]

=] it looks over-geared, the gov isn't working effectively, they do make an optional 12t, you may find that is all that's needed here, for gov performance and flight times....

[sctholson]

Originally Posted by georgi UK

=] it looks over-geared, the gov isn't working effectively, they do make an optional 12t, you may find that is all that's needed here, for gov performance and flight times....

I emailed Shannon at Only Fine Helis, he sells the DT line of helicopters. As far as he knows there is no 12t pinion available. The DT has a double helical main gear.http://onlyfinehelis.com/helicopter-...ath=2_219_296&

He's going to call the manufacturer and see if one is in fact available.

I would prefer a pinion alternative to changing the motor... I won't have a chance to fly until I'm home from work. I'll report back then.

[georgi UK]

=] would be a shame if they stopped producing the 12t?

[sctholson]

I just got a chuckle out of that. I'm always thinking that I'm so thorough... and boom... right in front of my eyes.
Well Shannon will likely report that back to me in a day or so when he hears back from DT.
Thanks for the smile

[georgi UK]

Originally Posted by sctholson

I just got a chuckle out of that. I'm always thinking that I'm so thorough... and boom... right in front of my eyes.
Well Shannon will likely report that back to me in a day or so when he hears back from DT.
Thanks for the smile

=] smiles are optional too!

[omerco]

Originally Posted by sctholson

no 12t pinion.

I was running at 1700 for flight time, but it doesn't look like the best set up. I can try raising the rpms to see if it effects the headspeed performance.

Using Mr. Mel's calculator, I should be somewhere up in the 2000 rpm range?

If I don't like flying at that headspeed, I will have to see if I can get a different kv motor and pinion combo.

check yourself here:
http://heli.dacsa.net/calcv3/Default.aspx

If you stay 13t than go up to 1900 or so.
if you stay 1700 you could consider even 11T...flight style dependent.

[sctholson]

Well that didn't turn out as I had expected. I was hoping for a nice smooth rpm and a smooth gov output, but in reality they don't look any different from the 1700 rpm flights Attached are three logs.
All 1900 rpm in Idle up 1
The first at 40 overdrive
The next at 100 overdrive
and the last at 100 overdrive and new batteries

All other settings are the same.

[sctholson]

It seems that every time I cross the collective from positive to negative there is a momentary dip in the gov output.

[georgi UK]

Originally Posted by sctholson

Well that didn't turn out as I had expected. I was hoping for a nice smooth rpm and a smooth gov output, but in reality they don't look any different from the 1700 rpm flights Attached are three logs.
All 1900 rpm in Idle up 1
The first at 40 overdrive
The next at 100 overdrive
and the last at 100 overdrive and new batteries

All other settings are the same.

=] the rpm is looking better to me, a lot smoother. no news on the 12t pinion?

[Only Fine Helis]

Hey guys,

I am working on DT making some 12T pinions for us, but it will be 3 to 4 weeks before I have them in.

However, I'm not sure that what I'm seeing is all pinion/gearing related. I have tried to duplicate the 1700 headspeed with an ikon fbl unit and don't seem to be getting the same symptoms that Scott is relating to me. (I'm running a scorpion 4520 520 motor) I am trying to get a couple of my pilots to attempt the same headspeed with different governors to see if they have the issue as well.

Is it possible that it could be a skookum issue either with the unit or in setup?

[sctholson]

The variables are motor, esc, fbl unit, sensor.

I've looked at the programming in the HW120A esc and it looks right, however maybe I need to revisit that. I am working from home today, so I can hook that up and post the settings if need be.

I was holding off changing too many things at one time. I would have through the 1900 head speed would have resolved the pinion/gearing issue.

[georgi UK]

=] it's no biggie by any means, the timing looks wrong but really you have a decent head speed, just fly the mother!

[sctholson]

Well Georgi, I don't give up that easy. I have always thought that the Scorpion website was wrong about the timing on this motor, as in they listed the timing as a mistake, but maybe it isn't. Anyway they show a pwm of 8khz and timing of 5 degrees. The HW 120 won't go to 5 degrees but it will do 7.5. So I've changed the ESC to 8khz and 7.5 degrees and that's my next flight.
After that, I'm upping the rpms to 2000 and going to overdrive of 110.
Dammit.... I want a smoooooooooooooooooooooooth rpm and governer output...