Hi Guys, hi Tomas

I have two Spirit 2 Systems in my Helicopters, one in a Mini Titan e325 FBL conversion, one in my newly built Trex 500 Clone that will finally find it's home in a gorgeous AH1 Cobra fuselage. Just for the record: The Mini Titan e325 flies perfectly stable in stabilisation mode (Coax and Normal).

I have a Problem with the 500 size "Torque Tube" Trex: It's setup is a Hacker A40-8L V4 8-Pole motor, 4 blade Align Head with Mikado CF blades, a 4 blade tail rotor (raised) and a Hobby Wing Platinum Pro 85A ESC. Flying on 6s 3300Mah Lipo. Transmitter is a Spektrum DX6, two genuine Spektrum satellite receivers.

I found a couple of threads in the forum describing the same Issue: It takes off and hovers perfectly in Stabilisation Mode for about 1.5 Minutes and then slowly starts to drift forward. I can compensate the drift until I run out of back stick.

After landing, the swashplate stays tilted forward until I reconnect the flight battery. Then the Spirit Unit reinitializes and levels the swashplate again. Usually, I can then empty the remaining battery (8 minutes flight time in total) without any other drifting occurence.

I followed the guidelines mentioned in https://manual.spirit-system.com/index. ... ing_flight so far. I removed the cooling fan from the ESC (not really needed anyway) and switched on "Extended Signal Processing" to no avail. I set the dead band of the sticks to 20. All sub trims in the transmitter are zeroed and all the directions in the diagnostic tab of the app are working correct.

I can't switch on the vibration analysis part in the app at the moment as this caused the app to lose connection to the Spirit unit... Odd... So I can't measure the level of vibes.

I just ordered some strips of 3M VHB tape (1.1mm thick) to replace the mounting tape I used - which was a generic gyro tape. The Spirit 2 unit itself is mounted on a metal gyro tray perfetly level with plugs pointing towards the rear.

Could the "wrong" tape have a negative effect on the sensors?
Another question is, if the Spektrum satellite receiver's connection cables rub on the frame close to the Spirit 2, could this also be an issue?

Last, but not least, I ordered a new autorotation gear, as the current one has a bit of a wobble and runs a bit rough during around 45° of a revolution...

Thanks for any hints and tips - and best regards - Paco

I would really start with the vibration analysis, self level not only on a spirit but all makes need to be on a model which generates acceptable amounts of vibration. The unit must be mounted firmly, with the supplied 3m pads it hardly moves when you try to push it. The wires ending at the uint side should be free and able to flex and not transmit vibrations to the unit. I had to balance every spinning part of my new heli to bring down the vibes. You mention that after the drifty flight you land and reboot and then the flight goes well? what about subsequent ones. is it occurring only on the first flight?

Hi Senaka, thanks for chiming in!

As the drifting occours on every flight with a fully charged battery, I suspect that - after a while - the RPM of whatever is causing the vibration is so that it influences one of the sensors in the Spirit unit. After the voltage of the pack and therefore motor RPM is below the level that it disturbes the sensor, it's fine again.

Yup, I'll try to eliminate every possibility of cause for vibrations in the next few days - starting with the autorotation gear and the mounting pad.

Cheers - Paco

very, very, very long ago i had the +/- same problem with a T-Rex 500 torque tube (with a different fbl then)... always with full battery, when i switched to highest rpm the heli rolled left strongly (needed more than 1/2 stick to compensate roll). after 1 minute, landing, re-start and it was gone for the rest of the flight.

in my case it was the torque tube tail... i several times replaced umbrella gears and TT itself and finally the problem was gone. never was clear which of the parts was finally the culprit (or a combination of parts). check with Spirit software, without any blades, on bench - the vibr. anylyse will show any torque tube problem very clearly even without blades.

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cheers
Michael

Hi Michael

Ah, perfect... Thanks for the hint! I already installed one of those nice TorqueTube ball bearing supports made by SK Rotorkopf, which made the driveshaft considerably smoother. They recommend using two supports per tube, so that would be another possibility.

And I definitively have to fix the issue that the Spirit software crashes when I hit the analyzer-button.

It's all part of the hobby...

Cheers - Paco

sounds like your getting some resonate frequency with a full charged pack and the difference in headspeed. Do you have the head speed readings when the drift occurs and when it's flying fine? you could try to adjust the head speed and see if it helps unless theres some significant imbalance is present.

I fly with a scorpion ESC and is governed to 2100 rpm which it happily reaches and maintains throughout the flight until the low voltage threshold with a fully charged pack. If I reboot the esc with the same pack after some running the ESC does some recalibration or some sort and will never reach the configured head speed, it will be lower. So in theory the vibrations created with the lower head speed after you reboot after 1 minute of flying looks to be within the acceptable range. that's what I think.

Hi Senaka - I think you found a viable solution for my issue.

After installing an additional torque tube bearing and putting the OEM one in the raised tail tube, the problem was almost gone. Upping the throttle "curve" (or rather governor rpm) by only 5% made the creeping dissapear. It's now perfectly stable for the complete flight. And as all components only get luke warm after 8 minutes of hovering, the setup is within all limits.

With a four blade main and tail rotor combined with the raised tail, I was halfway expecting all sorts of resonance... That will probably the case again after I add the fuselage anyway.

Best regards - Paco

Tomas he created for me a spirit software version where he fixed the crash.
I would pass you the installation file but must be zexx86 to authorize me to send to you the spirit version where he fixed the vibration crash

franz88: I am afraid his problem is very different than yours. It has nothing to do with software.

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Spirit System developer

Thanks Franz and Tomas!

Yup, I guess that the Issue that I had was certainly due to a resonant vibration somewhere in the rig. The parameters of the Spirit2 work fine within their limits.

A friend of mine had issues with his FBL unit too (not one from Spirit Systems) and finally was able to solve it by putting a layer of soft foam rubber onto the tail boom before installing it into his MD500 fuselage.

Cheers - Paco