naza H new problem - in GPS mode, the helicopter rock front and back.

[zentiger]

I fixed the manual mode tail problem But, now...I have another problem !!
When I flip to GPS mode, the helicopter rock front and back.
I lowered the Auto pilot front/back gain in the common tab to 40% , agility to 55%.
In the advanced common tab I lowered the velocity tracking to 60% but, the rocking front and back still there
Also, I checked the Cyclic Pitch and in normal it gave -0.05 degree and measure, it gave -7.1 degree. what is giving around 7 degree what DJI recommend.
If I need to lower the cyclic pitch mechanically, how can I do it ?

Do you have any other suggestion??
I really appreciate your guys suggestion !! without this site I think a lot of people already have give up of flying

[StripedGear]

What size heli is this that you are talking about? And what is the headspeed your running?

If you are going to fly sport or scale.. I would reset the gains back to where they were... and then reduce the cyclic pitch.. Instead of the 6.5 degrees.. see if you can reduce down to 5.0 degrees. This means that as the Naza is correcting for a stable hover.. that the movement of the cyclic pitch will be less. The Naza may be inadvertently over correcting and causing the rocking motion.

If your FBL gains are to low / high that can also cause osolations that gps mode may magnify.

Or your head speed is to low. There is no 1 answer to your question.

[zentiger]

Hi Stripedgear.
This is TREX450 pro, torque tube
I'm running a savox BSM-2940 (3500KV) with 150 main gear/13 pinion and 3 S battery (4 blade head/4 tail blade) this will give a head speed around 3000 RPM, if I have 90% efficiency (I also can run a 4S/12 pinion, but I didn't try yet).
I have tried very high gains and the heli oscillated front and back faster than the lower gains.(also tried several gains combinations medium, lower and high and the oscillation never go away. I can just increase or decrease oscillation speed.
I'm in 40% in the cyclic pitch tab (Ican't go lower) and 7 degree.
how can I mechanically reduce my pitch angle??? I never did anything like that. Which linkage do I need to change servos/swashplate or swashplate/head ??

[StripedGear]

You can lower the 7.0 cyclic pitch some more.
In the Mix Tab of the software there is an adjustment for collective pitch range. The default setting is 50%. If you have increased that number then you will have a higher cyclic pitch rate. If you have not increased that number from 50% then lower it to 40%.

Either way you will need to reset zero pitch in the Trim Tab to make the changes work right.. You will also need to set the default 60% in the Cyclic Tab before you reset zero in Trim. That will give you more adjustment room in the cyclic measurement and you will be able to lower the range less then 7.0

This will reduce the cyclic pitch rate.

That KV motor and gearing puts you at 2700 rpm at 90%. That's more like a 3D 2 blade speed not a 4 blade scale speed and thats at 3s battery.
You really need to lower the cyclic and collective pitch rates / range. And try and bring the rpm down to 2300.... and that may still be too fast.
The naza is giving small input signals but your heli is hyperactive and is over correcting. IMHO

[zentiger]

Hi Stripedgear ,happy 4th july l!!!!!
I just finished the settings that you advised me but, I could not change the range in the cyclic pitch tab. it still 7.0 degree
I did a series of photo to show my setting and the results:
- first I set the pitch limit to 40% and swashplate limit to 60% (zero the trim) and my total pitch range is from -11.7 to 10.5 degree with middle stick at 0.05 degree. (pitch curve and throttle curve at 0.25.50.75.100)
the results on the cyclic pitch tab are:
normal = 0.05 degree and measure 7.0 degree
So I went to swash mix tab and lower the pitch to 1% (minimum) and I still have 7.0 degree in the pitch tab between normal and measure.
so I guess change the limits do not change the pitch maximum range.
I'm stuck again

I will place a order in a new motor from Hobbyking:
It say that it is for 5-6S but, if I used in 4S nad 121 heliptical main gear, and 12 pinion I'll have head speed around 2230 RPM is it correct?
RotorStar Brushless Outrunner Helicopter - 2839-1700kv (450 size heli)
Specs.
Turns: 10T
Voltage: 5-6S Lipoly
RPM/V: 1700kv
Motor Poles: 6
Internal resistance: 0.065 Ohm
Max Loading: 26A
Max Power: 540W
Shaft Diameter: 3.175mm
Shaft Length: 15.7mm
Screw Mounting Spacing: 16mm (M3x4)
Weight: 79g

[StripedGear]

A 1700kv with 121/12 is to fast for proper governing.

As for the setup.. Go into you TX and change the Travels for Aileron and Elevator and Pitch only .. to 60% instead of 100% and reset Factory defaults in the software and start new. It's my fault.. I forgot to say to lower the Travel %... If you only have a range of -10 / +10 that fine.

This will slow things down enough and you will get less cyclic pitch,.

[StripedGear]

Its very hard to direct you. There are several things that could be causing you issues. It may be necessary for you to move the ball links on the servo horns in closer to center for a more efficient resolution. My big as350 the balls are way in to center and the Travels are at 60%. You need lower head speeds due to 4 blades and then you need to find the correct FBL gains so you dont oscillate. There is alot going on here..

[zentiger]

Hi Stripedgear,
Ireally appreciate your help .
I know that is very hard to guess somebody else setting without seeing what is going on. Your advice is always very good !! looks like you have a lot experience.
I was thinking about that yesterday and I changed only the travels but, I couldn't test yet.
Yesterday, barbecue was first priority ;o) !!
I’ll reset the program and do it again today, (I forgot that.)
I’ll post the results tonight, I’ll be doing one change at the time so, I keep tracking the effect of each change.
Again, thanks for all your help !!! “Try and error is one of the best method of trouble shooting”
What do you think about the scorpion 2221-12 - 150/12
I added a screen shot of castlecreation calculator

[StripedGear]

Ive not seen that calculator before.. I use the software in Demo Mode.. Anyway.. with that motor and main gear you would need a 15t pinion to reach 2400 rpm @ 93.0%..

Why don't you search and find out what is a good head speed for a 450 size 4 blade rotor head... and then research motor and gearing to get that rpm. I only have big helis that use low head speed.

[zentiger]

Hi, an update
I try today to do what you told me
To start:
-I set 60% travel to Aileron, Elevator and Pitch in the TX
-Reset Factory defaults in the software and set in the Mix tab 85% for swashplate limit and 45% for collect mix - pitch
-I set 50% in the cyclic pitch tab
After a lot of back and forth, I got 5.5 degree in cyclic pitch measure stage but only after I changed the ball link location to one hole in (I re-leveled the swashplate)

I tested fly today and the oscillation is better but, still there. I tried several gains combination but no improvement. Also, I did not have a good GPS lock. It was moving around (no red led blinking).

Next step will be change the motor. I'll be looking for something around 1600 to 1800 KV, so this will give more flexibility to work with pinion.

I just wondering, Could it be a bad IMU ?

[StripedGear]

Thats very good.. You got 5.5 cyclic pitch.
As for the gps not locking in place.... you need to be flight trimmed and the gps and atti work better.
What I do is to put the heli in a gps stable hover and flip back to Normal and see what the heli does.. If it moves forward I go back into the software Trim Tab and bring the elevator back a couple of points. and then fly it again.. I continue to do this until when I flip back to Normal the heli stays in place..

Then I repeat the process by flipping from gps to Atti mode. if in atti mode it drifts left.. then on the Common Page I adjust the Atti trim slider right a few points and fly again. And continue until flipping to atti from gps the heli stays put.

So in the end you can flip from gps to normal and atti and the heli stays in one spot.. And cause the heli is trimmed in atti and normal then the gps will work the best possible.

Do this in calm air. It takes a little while to do but is well worth the trouble.

[zentiger]

Hi
I bought today a 1700 kV motor to be used with 4s and 150/13 gear combination.
Using castle creation calculation I will have a head speed around 2250 rpm.
Provably, I'll have it by the weekend I hope.
After, install it I'll see if the oscillation stop and if it is ok, I'll follow your tunning method, it make a lot of sense.

[StripedGear]

That won't work.. That would be 114.0% @ 14,8v. A 121/13 would be 92.0% A 121/14 would be 85.5% all at 2250 rpm.

[zentiger]

Hi,
I do not know to much about electric motors but, castle creation has a flight calculator with a lot of inputs necessary to get the result and the information that come from its calculator is very different than your calculation.
if I use a scorpion 2221-12, 150/15, 4S. I'll have max head speed =3205RPM and they do not recommend to use, .
for a 2221-12, 150/12 and 4S, I'll have max head speed =2672RPM and they do recommend to use
I added a screen shot of these calculations.
here is the link:
http://www.ecalc.ch/helicalc.php?castle&lang=en
Did I have do anything wrong in the program inputs ??

Well, I'll have this 1700KV motor by Saturday anyway, I'll install and try to use it with 13 pinion and see what happen.
The head speed will be low and I will see if the oscillation will stop
Today, we have no wind at all here, I change the heli to 12T pinion and the oscillation still there.

[StripedGear]

I dont know what to tell you.. I am using the actual CC software for Set RPM. As I said I have never seen this calculator that you are using. I'm using the software as if I am programming the ESC itself. The only difference is that I am not Updating it to the controller. If you have a castle esc you cannot program govenor / set rpm without this software

[zentiger]

hi,
I'm using a castle creations Phoenix edge 50 in all my three heli, it is very reliable and easy to program.
I'll try this new 1700Kv motor with 121/13 gear and see if works.
It was inexpensive, if it really solve my oscillation problem I'll buy something better.

[zentiger]

Hello,
here is a update:
I tested three motors
- Savox 3500Kv,
- Scorpion 2221-12 2650Kv,
- Hobbyking 1700k
I bought pinion from 11T to 15T
My head speed was from ... very low that I almost couldn't hover to speed around to 3000RPM,
I had tried a lot of different gains combination.
the best combination was when I set all gains around 50% (flybarless included) and back/front 40% but, doesn't matter what combination I use only thing that I can do, it is lower the oscillation frequency.

Well, I really do not know what to do from this point on.

[StripedGear]

Like I said before you should ask around for what is a good head speed for a 4 blade 450. I did setup a 450 with a 3 blade head for a Blue Thunder Drath fuselage with the Naza H. RPM was 2500. You know how the do the setup in the software so I will tell you our gain settings for that heli..

On the Common Page Basic tab

Atti L/R 85% Atti F/B 85% Vertical 85%
Agility 85%

FBL Gains
Aileron 100% Elevator 100%

Cyclic Rate
140% 140%

In the Advance Page leave all settings at Default

The heli flies great.. Remember you have to set mechanical bias for the tail rotor for the gyro to work correctly.

I do not remember what motor kv and gears we used but I can call Richard and ask tmr.. I think it was
2750 kv - 121t main gear - 13t pinion which equals 2500 rpm @ 85.0% on the esc.

In my experience in setting up several Naza H heli the basic Atti gains have always been 80% to 100%

[zentiger]

Sorry delay to return to this post but, I was out of country
To understand where and what is causing the front/back moviment
I swapped the four 4 blade head with my trex450 2 blade dfc head and set up again.
I did a quick fly before travel and looks like that the front/back movement disappear. I'll fly again to confirm.
Well, I think that I found the source of the problem, now I need to identify what in the head is causing it.
I had phasing this head 90 degree mechanically, I'll give some degree (+ and - ) electronically and see the results.
Also, I'm using a flexible main blade, I'll be replacing it to a align carbon blades.
I'll be doing all This changes individually to try to find the source.
If you have any other ideas, it is welcome.

[StripedGear]

Yeah get rid of those flex blades.. Your rotor needs to be as ridged [stiff] as possible.. That could be the whole problem.. When you went back to the 2 blade head were you using stiff blades??

You are having the same issue I had with my 700 size AS350 with a 3 blade head. rocked back an forth in gps mode a lot.. I was very frustrating..
Finally after 6 weeks of trying everything I could think of I gave up.. That's when a friend brought me a complete Goblin 700 2 blade head and swash. I installed the head and the heli flew rock solid with no issue's at all... I thought of leaving it on there and not use 3 blades but it's a scale heli.. So I bought a new Century Diamond 700 3 blade head. Most all of my issue's went away with the new head.. however, it can still get a little rock going if it's windy.
The other thing is that you need to make sure you have the CG center of gravity set perfect. If it is nose or tail heavy then the GPS will fight the heli.