Hello,

Bascially i am very happy with the fbl unit, but i have to get rid of some quirks on my heli. Therefore i have some questions.

1) When i fly sideways from left to right, my tail wont hold position and drifts a little to the left (like a tail in stall turn). Unfortunatelly it wont come back to the original position, i have to move it back with rudder input. At first i thought my piro consitency is too low, but if i increase the value i have tail flutter on pitch pumps. Any ideas?

2) My tail wont hold during pitch pumps. No matter what i do. (Its a protos 380 with 2800rpm and 12° collective pitch). I have set piro consistency to 150 and maxed out tail gain until fast wag, reduced some points and then increased piro con. until i had tail wag at pitch pumps and then reduced it again, but the tail wont hold and kicks to the right (tail gain = 55% and piro con = 160). If i make a flip and catch it with pitch or make a rainbow my tail is kicking a bit and then settles. As per manual i dont want to use revomix, if possible (i tried up to 5, but than had to reduce tail gain and tail still wont hold or is overreacting)
Tail mechanic is smooth when i move the slider by hand (with tail blades mounted and spinning).
Tail servo: MKS HV93i with rudder delay set to 0.

3) It seems that my tail bobbles up and down a bit if i make a pitch pump. Or if i make a flip let it fall down and make a hard stop it seems that i get the above mentioned tail kick including a up and down movement? It doesnt matter if inverted or upright. What could be the cause for this?

Would be nice to get some feedback.

Thanks a lot.

Hello,

1,2) both two points are very likely related with the same source of problem.
Could you please attach your settings here? Without seeing how it is configured it is hard to help more.
Very likely your Pirouette Consistency is too low, while Rudder Delay too high. You can try to set 175 value and Rudder Delay at 0.
Was the model flying well previously or it is new setup?

3) This is usually result of swashplate/servo centering or wrong center of gravity. Certain part of the problem could be caused also by bad rudder performance. You can review this guide:
http://manual.spirit-system.com/index.p ... d_Geometry
And make sure that while you were doing the configuration your steps were same. Otherwise an imprecision could be present that is responsible for this and possibly other things related with the flight performance.

Wrong but possible solution would be to try to increase Cyclic Gain, but this effect should not occur normally with any Cyclic Gain.

_________________
Spirit System developer

As mentioned above, rudder delay is at 0 and piro consitency cant get any higher or i get a wag, but please see the attached file. At the moment i have piro consitency and revomix on a special function channel, so i can adjust the values in flight. Same goes for over all tail gain, which is at 55%.


My mechanical setup is fine, i will check CoG, this could be a bit off.
I tried to mess with cyclic gain, but i had the feeling that it will get worse with higher cyclic gain.

I couldnt sort my problems until now and some more questions popped up, so i want to keep this thread alive and add some more tuning questions until i know the heli cant do any better or the problems are solved.

Tail kick:

Here is a little explanation of what i am observing.
If i make a moderate pump from hover (about 60% stick) to lets say 75% stick deflection i can see how the tail is slightly moving to the right.
If i make a fast 100% pump its kicking about 10-20°.

Its holding perfect during speed funnels, loops and so on. Its just that i cant get rid of this annoying kick.

What i did so far:
1) Updated to the newest firmeware
2) Changed the servo ball to the inner most whole --> no change to flight performance
3) Made the tail assemble so smooth that its falling under its own weight and if disconnected from servo and spin it up without blades its moving without sticking over the whole shaft. (i measured the force with a scale and it was aprox 500g to 600g through the whole shaft)--> no change to flight performance
4) Installed a new tail servo (MKS HV 93 i), just to rule out that the old one got damaged during some crash. --> no change to flight performance
5) Installed new tail belt. --> no change to flight performance
6) Installed new tail bearings (tail shaft and grips). --> no change to flight performance
7) Set the hover tail pitch so that there is no drift in rate mode --> stops got more symetric
8) Changed gov parameters up to the point that i know its not a gov problem
9) Changed bec voltage from 7.4V to 6.0V --> no change to flight performance (so set it back to 7.4V again)

Tail tuning questions:
1) If i change rudder delay, do i have to tune the gains again?
2) Rudder delay is at 0, because thats the suggestion for this servo (MSK HV 93 i). With which maneuver i can determine if another value may be better for my tail?
3) Is the rudder dynamic value only for stops, or can this also play a role in kicks and holding performance?
4) Do you have any suggestions what else i can/should do?

Cyclic bobbles/shakes:

During tail down elevator tictocs i have a weired shake going through the heli. Always at the point from changing collective pitch direction from pos to neg and vis versa the heli is first shaking and then accerlerating.

What i did so far:
1) Installed new head dampers --> Problem got better and pitch response got better
2) Installed new blade grip bearings (were just a little bit notchy) --> Not sure, but dont think it had any effect
3) Installed new ball links (some were a bit sloppy) --> pitch response got better
4) Checked Cog, its only a little bit off. Piros are not 100% flat, but the heli is only drifting a little bit over time.
5) Changed the phasing angle --> Elevator flips are now straighter and more precise
6) Reduced head gain to 45% --> Bobble and shakes got better

During my research i found a pilot with the same problem and he got the suggestion to change the 6° geometry instead of cyclic gain.

Head tuning questions:
1) What exactly is the 6° geometry doing and what part of the performance would change if i dont set this exactly to 6°, but lets say to 7°
2) How can i determine if changing the geometry is better then head gain and what ill effects i can encounter if the geometry is changed?
3) Does phasing have an impact on the 6° geometrie?
4) Do you have any suggestions what else i can/should do?

The rest of the specs are same as stated last year:
Heli: Protos 380
Pitch: 12° (maybe a bit less)
RPM: 2800
Gov: Hobbywing
Blades: Rotortech 386mm

I kindly ask for your support and please see the attached config file.

Thanks a lot.

Edit: I noticed you dont see the tail gain value in the viewer, because its configured via my TX. I have the tail gain set to 72%.

@ZeXx86: Any answers or suggestions?

Does your tail kick to the right when you do a pitch pump?

I have 3 helicopters oxy2, oxy3, trex 450 every single one of them I had to add revomix to get that to stop. I'm not fond of the idea of adding revomix either but its the only thing that got rid of the kick. I used values from 2-4.

Yes, its to the right. I wanted to take revo mix as my last resort, because i wanted to understand the tuning system as good as possible and it was stated very often, that revo mix shouldnt be needed at all.
Hopefully zexx will have some time in the near feature and i can get all the answers i need to solve the issues.

Hello,

I am sorry for delayed reply.

One of the most important parameter is Pirouette Consistency, this is actually exactly parameter which is affecting what you are observing. So changing the value should help a lot.

Tail tuning questions:
1) Usually it is not needed. Correctly configured Rudder Delay will allow higher gain.
2) It should be somewhere between 0 - 3. Any value from this range will have rather small impact on the performance.
3) Only stops and steering.
4) Pirouette Consistency - as described in our tuning guide http://manual.spirit-system.com/index.p ... ning_Guide
You can try to set value of 175, but not higher.
Revomix should never be higher than value of 3 in a normal circumstances.
Governor has major impact on the rudder performance, so you can check if it is configured well too. With HobbyWing it is usually fine.
With Protos good belt tension is critical as well.
Next thing is RPM, if it is too low then performance could be worsened.
Another big impact has Pitch range and lastly rotor blades. More aggressive blades will require better rudder performance.


Head tuning questions:
1) It will affect performance and flight behavior a lot. You could observe other oscillations or too agressive behavior. It could be more stable but also less natural. This is not good solution.
2) Experimenting with different Geometry value is rather bad idea, if it will be better than it is only making the main issue/reason less apparent.
3) Cyclic phasing should be always correct, 0° for your helicopter. Please set 0°.
4) Reason why you are obsering the problem is caused by poor tail performance. When tail will perform well the cyclic will work correctly too. When rudder is unable to hold the where it should be then any movement of the model is transfering from rudder to cyclic. So it is enough to leave everything at default and to fix the rudder performance.
Higher RPM and a smaller Cyclic Feed Forward could help.

_________________
Spirit System developer

Hello,

Thank you for your reply, dont worry if its a bit late, we all know how busy you are trying to keep all of us happy.

I have answered or questioned some parts in your quote in red color. If you would be so nice and and help me warp my head around the last bits.

Do a constant pirouette in any direction. Now let go of the stick how hard the tail stops in its tracks when you let go is the best way I can describe that feature. Dial the value up the stops are immediate. I like hard stops I usually run a value of 9 or 10.

It would be helpful if you guys listed the timing for each range you call very fast, fast, slow ect. I know you guys try to list the values for each servo which is also helpful but like the KST 215 you have nothing. It would be hard for you to keep up with every servo. If you listed the timing for each range that might be easier.