Hello all,
I had been flying an M4 Spirit combo for over a year without issue. After a bad crash and rebuild, I had a mild tail wag. I found some mechanical issues on my part that exacerbated the issue. After issues corrected, I still can see a mild wag. It is present at as little as 5% gain. The oscillation's increase as the gain increases (30-50+). This is consistent at all of me head speeds from 11000-16000. I replaced every part on the M4 to no avail. I actually purchased a second M4 with 100% all new parts to include ESC and the issue was present on the new one as well. I installed and old AR7200BX in place of the Spirit and the tail was locked. Both Spirit units provide a locked in tail when Installed on my Nimbus 5000. So, the issue only manifests when a Spirit unit is married to an M4. It is gentle, but obvious to me. I would appreciate any help as this issue has cost me a great deal of time and money. I did try playing with the dampening values. This may have helped slightly, but not by much.
Latest firmware installed.
Thanks,
Tony
OMP M4 tail wag
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tonycampophoto
- Posts: 3
- Joined: Mon 09. Jun 2025 22:23:13
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Hello,
please make sure the Spirit unit is mounted at the hard mounting pad. The pad has to be different from AR7200BX because it has different weight.
Your settings is looking good. From your description I would think there is something in the tail to not move freely (any additional friction makes the tail wag more apparent).
However since it works with other unit it could be because of damage of the Spirit or your AR7200BX is configured to work even with this friction.
Possible damage to Spirit unit is loose PCB which could happen if 4 screws at the bottom are not tight. You can gently try to tight them.
If it is caused really by mechanical issue Spirit can be configured to make it work too by decreasing Pirouette Consistency as low as possible. Then increasing Revomix will make the tail to work. But this solution is not good. Servo will be under high load all the time, possible with not ideal performance.
I hope something from this will help you.
please make sure the Spirit unit is mounted at the hard mounting pad. The pad has to be different from AR7200BX because it has different weight.
Your settings is looking good. From your description I would think there is something in the tail to not move freely (any additional friction makes the tail wag more apparent).
However since it works with other unit it could be because of damage of the Spirit or your AR7200BX is configured to work even with this friction.
Possible damage to Spirit unit is loose PCB which could happen if 4 screws at the bottom are not tight. You can gently try to tight them.
If it is caused really by mechanical issue Spirit can be configured to make it work too by decreasing Pirouette Consistency as low as possible. Then increasing Revomix will make the tail to work. But this solution is not good. Servo will be under high load all the time, possible with not ideal performance.
I hope something from this will help you.
Spirit System developer
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tonycampophoto
- Posts: 3
- Joined: Mon 09. Jun 2025 22:23:13
Thank you for the reply. The issue is the same with two separate Spirit GT's on two separate M4's. So, that basically removes damage of the Spirit unit from the equation. Both M4's behave identically in tail behavior with both Spirit units.
I have tried the settings you mentioned, but will try again. Best results were setting Rudder Delay to zero and moving ball to inward position on pitch slider. I am not a fan of the M4 V1 tail section. I have them as free as is possible. And yes, AR7200bx does not have issue locking tail on M4. I will try to post a video of this subtle tail anomaly. I would swear I did not have the issue the whole previous year that I flew this combo. Maybe I did and did not pick it up.
I have had good results with standard 3M tape with these units in the past. But I will indeed order the correct pads as suggested.
FYI both Spirit units lock tail in on the larger Nimbus 5000.
Thank you again
I have tried the settings you mentioned, but will try again. Best results were setting Rudder Delay to zero and moving ball to inward position on pitch slider. I am not a fan of the M4 V1 tail section. I have them as free as is possible. And yes, AR7200bx does not have issue locking tail on M4. I will try to post a video of this subtle tail anomaly. I would swear I did not have the issue the whole previous year that I flew this combo. Maybe I did and did not pick it up.
I have had good results with standard 3M tape with these units in the past. But I will indeed order the correct pads as suggested.
FYI both Spirit units lock tail in on the larger Nimbus 5000.
Thank you again
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AndrewJohnHawes
- Posts: 145
- Joined: Thu 21. Apr 2022 1:34:02
I have originally had somewhat good results at a head-speed of about 1840 rpm and a cyclic gain of about 48.
Subsequently, very slightly increasing head-speed to closer to 2000 rpm I got significant tail bob.
This machine is supposed to be happy with higher head-speeds!
Any advice, or experience in terms of cyclic gain?
Regards,
Andy
Subsequently, very slightly increasing head-speed to closer to 2000 rpm I got significant tail bob.
This machine is supposed to be happy with higher head-speeds!
Any advice, or experience in terms of cyclic gain?
Regards,
Andy
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tonycampophoto
- Posts: 3
- Joined: Mon 09. Jun 2025 22:23:13
Posted this in another forum. Sorry for the bother.
It is not the Spirit units. They are fantastic FBLS's. The issue is with the M4 design in my opinion. Here is the latest.
First, I will say that I am so very impressed with the Rotorflight and the Nexus fbl. A bit of a learning curve, but I feel comfortable with it now. I have been through every setup video and still have wag on both M4's. I feel that I have gone above and beyond what anyone should have to go through to get a solid tail.
Here are the constants:
I have two M4's, one brand new and one rebuilt with 90% new parts. I spent hours to get tail as fluid as is possible. There is little to no binding.
Both M4's have sloppy wagging tails with (2) Spirit GT's and now with the Nexus.
Wag is nearly non-existent with old AR7200bx. I feel this is probably due to it being old and has far less demanding requirements for stable tail. This seems counter intuitive.
Today I will try to understand and master the noise tuning. This could make a big difference.
I guess I deserve whatever happens with the M4 Max I have coming tomorrow. If it wags, I will probably drive off a tall bridge here in West Palm.
It is not the Spirit units. They are fantastic FBLS's. The issue is with the M4 design in my opinion. Here is the latest.
First, I will say that I am so very impressed with the Rotorflight and the Nexus fbl. A bit of a learning curve, but I feel comfortable with it now. I have been through every setup video and still have wag on both M4's. I feel that I have gone above and beyond what anyone should have to go through to get a solid tail.
Here are the constants:
I have two M4's, one brand new and one rebuilt with 90% new parts. I spent hours to get tail as fluid as is possible. There is little to no binding.
Both M4's have sloppy wagging tails with (2) Spirit GT's and now with the Nexus.
Wag is nearly non-existent with old AR7200bx. I feel this is probably due to it being old and has far less demanding requirements for stable tail. This seems counter intuitive.
Today I will try to understand and master the noise tuning. This could make a big difference.
I guess I deserve whatever happens with the M4 Max I have coming tomorrow. If it wags, I will probably drive off a tall bridge here in West Palm.
Thank you for the update.
I have to confirm that from the beginning M4 was released there were peoplle that were unable to tweak Tail. Only after lot of tinkering and making tail smooth mechanically it started to work well.
Unfortunately many new kits require some work to make everything smooth. Not all kits are ready to fly out of the box. The main issue that is causing troubles are too tight ball linkages. Without a ball reamer it could move very tightly (for years). At Tail even very little friction can cause problem.
For example some kits are designed so that push rod guide is bending the push rod. This is very wrong and has big negative impact. With adjusting tail servo arm position carefully it can be resolved (or doing mod to the guide).
AR7200BX is using old sensor. Old sensors required to have big deadband for a movement detection. It has positive effect when mechanics is tight because it will simply dont make any very small corrections. Without small corrections tail wag is not visible.
It can be easily added for recent units too, but it has drawbacks causing other imprecisions.
I have to confirm that from the beginning M4 was released there were peoplle that were unable to tweak Tail. Only after lot of tinkering and making tail smooth mechanically it started to work well.
Unfortunately many new kits require some work to make everything smooth. Not all kits are ready to fly out of the box. The main issue that is causing troubles are too tight ball linkages. Without a ball reamer it could move very tightly (for years). At Tail even very little friction can cause problem.
For example some kits are designed so that push rod guide is bending the push rod. This is very wrong and has big negative impact. With adjusting tail servo arm position carefully it can be resolved (or doing mod to the guide).
AR7200BX is using old sensor. Old sensors required to have big deadband for a movement detection. It has positive effect when mechanics is tight because it will simply dont make any very small corrections. Without small corrections tail wag is not visible.
It can be easily added for recent units too, but it has drawbacks causing other imprecisions.
Spirit System developer