All,
I’m having an oscillation issue that I and others can not seem to correct.
First I’ll give you all the background on myself, the others that are involved in helping and what we’ve done.
As for myself this is my first large helicopter setup, meaning a FB’s unit. I have 15 year’s experience with large 3D airplanes and complicated setups. The others both have well over 20 years of experience with helicopters and multiple brands of FB’s units (this is our first Spirit FB setup).
I’m using a Jeti DS16 II radio with a Spirit GRT FB’s in a Tron 7.0 Dnamic heli.
My initial setup was done by following John Hamel’s YouTube video. John’s setup was done using a Jeti radio.
Maiden flight: my friend met me at our field and reviewed my setup and controls. The heli lifted off in Normal mode without issue. In IU1 we saw some oscillation in the cyclic (head) the tail was rock steady. Landed and adjust the cyclic gain up/down with no change to the oscillation. At this point I setup the telemetry in my radio to log the FB’s units vibrations and the FM switch. The log did not show access vibration at any point, in the way I interpreted the data, the vibrations smoothed out once I switched to IU1 (attached). At that point we did a quick search on the Tron FB page about oscillation on the Tron 7.0 and found that some people had to change to stiffer dampers.
Ordered, installed the dampers and flew it and in IU2 the oscillation was gone. It was basically a quick flight to check to see if the dampeners corrected the problem. At this point it seemed like it did.
The next time we all met at the field, when I went to IU2 (1600 rpm) the Heli started oscillating, not the shaking as it did during the maiden test flight. Landed and adjust the cyclic gain up/down with no change to the oscillation.
One of the guys that has been helping me has the same Heli. We took his swashplate, head and blades off his and installed it on mine. My friend flew it several times without ANY oscillation. My friend started tuning the FB’s unit and talked about how “locked in” the FB’s unit felt to him. We then started looking at my swashplate and head to see if we could find anything wrong with any of the parts. We did find what we thought was excess play on the swashplate bear. Other than that, nothing stood out.
I ordered and installed the new swashplate, it still oscillated in IU2. We then again took just his head and blades and installed it on mine. This time the Heli still oscillated in IU2.
Two times the Heli flew as it should. One after the dampeners were changed. The other after we switched heads. But then when we switched just the head yesterday, it oscillated.
Could I lower the frequency setting on the cyclic servos?
We are now at a loss!
Thank you in advance,
Scott

Hello,

could you please share Spirit settings file? I will check your settings.

Lowering servo frequency is not the best solution, but you can try it.

I suspect too high Geometry 6° value. Also make sure that antenna tips are not too close to servos.

_________________
Spirit System developer

I believe I downloaded the correct file?

I also added two pictures of my antenna position. There as far away as possible from the servos.

Thank you for your help!

Because my friend has the exact same Heli other than the FB’s unit, before I started adjusting the Geometry 6° value I wanted to change the dampeners back to the original Tron S70 to match his Heli.
The original Geometry 6° setting was 104. On my first flight I set it down to 99 and the landing gear still had some oscillation, but it seemed better. The next flight was done at a Geometry 6° setting of 95. There was very slight oscillation in the landing gear. I lowered the Geometry 6° setting down to 91. At 91 the oscillation was gone.
The only adjustment that was made after the Geometry 6° was set at 91 was the tail gain.
Not knowing what the Geometry 6° does, do my settings look correct? Would you recommend any other changes? I attached the new file Tron7.0 3-17-25.
Thank you for the help,
Scott

An off topic question. I need to reflash my GTR, should I have any concerns or recommended checks after the reflash?

Hello,

your settings looks good, except I would change Elevator Filter to 3 - 4.
Geometry 6° is quite important parameter and is model/servo specific. Each model has little different value and it determine overal system gain for your mechanics.

_________________
Spirit System developer