Static or...?

[Russell Harding]

My P700 has been good to me so far, but recently developed a 'tail twitch'.

It first happened on a tail down, skids out, CWW funnel (which I know is hard on the tail), I thought it may be mechanical since that can be tough on the tail, but I have not found anything wrong mechanically. Since then it has happened a few more times in various flight states: moderate speed forward flight, loaded and unloaded head, etc.

The symptom is a sudden, extremely brief 'twitch' of the tail (mostly... there seems to maybe me a jerk of the cyclic too, but tail is more pronounced... It may be interaction from a hard tail jolt, or maybe not). The tail twitches 15-40 degrees and does not bounce back. It happens about once per flight. It is extremely brief and extremely violent.. there is a bit of a 'crack' when it happens... This could be blades biting the air or something else. It has happened about 10 times and has not worsened or ever been anything more than a twitch/jolt/jerk type incident.

So: Could this be static? (never had static issues with a protos). Or something else I should look at? If static could be a cause, how much trouble would it be to attempt to mitigate to help rule it out?

Thanks in advance!

[crickr1]

how many flights on belt? Usually they wear evenly but on my P500 I had a belt loose a couple teeth and on occasion would Twitch or skip a beat but then be right back on track. The tricky thing was, the teeth were not missing. They were torn in a way that they rolled over under load. Worth a thorough inspection as I have not heard of any Static hits on the Max. Not saying isnt possible but leaning toward mechanical.

[Russell Harding]

Belt was recently replaced and is in good condition. I can check the whole of the belt though and see if some spots are worse. My last belt did seem to be slipping slightly and a lot of kevlar bits showing through the teeth. Mine are currently fresh rubber and about 20 flights at most.

[alexf1852]

The tail twitch is a symptom of a static hit.
Has it been dry weather in your area?

The only sure way I've been able to eliminate static hits without spraying the belt is to ground to battery negative. Make sure you have continuity from tail to CF frame. Then ground CF frame to battery negative. That will solve static issues for good.

[Russell Harding]

Humidity here runs 20-40%... Dry.


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[alexf1852]

Originally Posted by Code3Medic

Humidity here runs 20-40%... Dry.


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Then is most likely static.

[OnTheSnap]

The Max like it's smaller friends has integrated static management in the design (exposed boom ends, metal clamps). Please ohm out your tail to motor (on exposed metal parts, not anodized) to verify there is some conductivity.


Other theories:
1) Tail servo failing
2) RX poser system issues - I've had some cyclic servos impact the operation of the tail servo. Power transients caused the tail to misbehave. Adding a servo power bus and putting the tail directly on the FBL unit with the cyclic on the power bus solved it


Are you running a Brain? If it's a FBL unit with logging you should be able to see evidence of ESD hits in the log.

[Russell Harding]

Vbar silver line. Unknown about logging, personally.


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[OnTheSnap]

Originally Posted by Code3Medic

Vbar silver line. Unknown about logging, personally.


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Ok Vbar has logging. That's the first place you need to look to see if it's static. You will see some severe errors.

[jmtyndall]

Vbar has a log bud. At the top of the screen, there are some menus, file, parameter etc. under one of those you can download the logs. You'll be looking for any entries that indicate resets, warm starts, sensor failures or receiver failures. Basically anything unusual. If there are no issues you should have a "good health" log every ten seconds

[Russell Harding]

Apparently logging is a pro option. I've been meaning to upgrade anyway so I can have auto-bailout.

I buffed the anodization off the boom and had no continuity with anything else on the frame. I grounded the boom to the lower frame screw and there is now continuity from the far end of the boom screw to the motor mount screw.

I'll upgrade to pro, do some testing, and report back.

Thanks.


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[jmtyndall]

Pro is worth it for SO many reasons. I couldn't stand xpress and so I have upgraded all my vbars

[Russell Harding]

It flew very, very well with the express setup. I didn't have too much reason to upgrade with the exception of the gov and bailout. The YGE gov has been fine but I've always had better performance with FBL govs.

I also REALLY want to do an inverted auto but I will need bailout to do some high altitude practice with bailout to get a feel for it.

Already got it installed and will be flight testing tomorrow.


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[Russell Harding]

Ok. With Pro I can now see my logs... I take it this is not normal? (Sarcasm)



The vibrations may be accurate... Heli has been crashed prior to my ownership. Looks smooth enough in the air, although there is some tail vibration I couldn't resolve completely by dynamic balancing.

From a quick search, the sensor checksum errors point to static.


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[jmtyndall]

Holy FAWK. Abort lol.

My 600 is funny with vibes. Sometimes I'll go three flights with no warnings, then one flight ill get two or three raised/excessive vibration warnings. Without changing anything. I'll worry about it when "excessive vibration" starts showing up as much as "good health".

Thats neither here nor there. There's definitely a problem in that log

[OnTheSnap]

Bad bad bad.

Could be static, bad cable to sensor, or a bad sensor.

[Mercuriell]

I'd say a vibration issue. Check out the vibe spectrum from a bench test, NO blades and tail pushrod disconnected and post a screen pic. The controller is basically losing input from the gyro, probably because it's blinded by vibes.

[Russell Harding]

Setup the pro software, vbar gov, and bailout after a few hours tweaking last night.

Test flight revealed no checksum errors and no tail twitch. Perhaps static was playing a role.

And obviously there are vibe issues as well. I think I detected some buzzin on the main shaft so I think I'll start there.




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