Odd tail problem

[ryem3]

Well, I've read the threads about the Pro tail bearings. And about tail setup. I'm still a bit stumped.

I crashed my bird a little while ago. Never figured out the reason. Broke all my servo arms, bent the main shaft and stripped a servo. After rebuild it seemed fine, then suddenly began to piro after I put it in idle up. Couldn't control it and I crashed again. This time, bent another shaft, the boom, the gear, and the ball ends on the grips. Figured there was no point in getting the old grip set and shaft, I got the new DFC head.

Got everything set up fine. So easy now with the FBL geometry. I hover it in normal, seems fine. Then starts to piro again. Finally dawns on me, must be those tail grip bearings. I take apart the tail, bearings seem fine. I read that others have bad bearings that seem fine too. I take the tail off and add a 450SE tail I had laying around. Plastic blades. Try to hover it. It just drifts. Badly. Occurred to me, maybe I should have rebound it after doing the tail. Take it home and rebind it. Reset the endpoints in the Beast. Didnt change a thing. Tail still needs to be corrected right in order to fly.

I don't get it. Thinking I should just lube the pro bearings a bit and use the pro tail again. Order some Bocas in the meantime. If I'm flying in HH and set the endpoints, how much should any geometry matter as long as it moves to both ends without binding? You don't use any trim to get the tail square anymore with FBL do you? I'm stumped. If I move my tx gyro settings to rate mode, how do I set the tail slider to the midpoint without using trim? Only with the tail rod? (using a carbon rod with no guides). What's the difference as I said earlier if I'm flying HH anyway.

[ryem3]

Any suggestions?

[chrismechanic]

you should not need to setup rate for the beastx to hold the tail, but it will help..around 6 -7 degrees is the normal setting..with tail servo at 90 degrees...then reset the tail endpoints in the beastx.
yes use the carbon rod to adjust the tail slider to the desired setting.
it coulld be vibrations going to the gyro which makes it drift, check the airframe for vibes while it is spooled up...be carefull..pin the heli down some how so it cant take off or swing the tail around, mind thoses fingers.
no..dont use any trim at all.
what radio and what gyro settings are you at? both rate and hh.
chris

[ryem3]

I'd be surprised about the vibrations, but I suppose anything is possible. I just went to the helical gear on it, if that makes a difference.
Using a DX8. I had it at 40 on HH and spun it down to -30 to check out rate mode.

I was sure it was the pro tail grips, but now I'm baffled. Bad weather here, so I didn't try anything yesterday.

[chrismechanic]

i had a crash a few weeks ago...some how damaged my motor...chasing vibes i ended up with just the motor in the frame and the vibes sent the beastx crazy...all servos twitching up and down.
i cant fly it like that so im grounded until the motor is fixed.
helis dont like crashes .
i have to send my motor back to scorpion the be checked over DOH....
your gain settings seem about right. but drifting..both cyclic and tail is a good indication of vibes getting to the fbl controller.
chris

[ryem3]

I took a good look at the mechanical setup and it was WAY off. Control rod was way too short. I got it longer, set the gyro setting to rate mode, centered the servo and squared the tail. Good setup. Reset the endpoints in the Beast.

Took her out. Hovered a pack. She was LOCKED. Really solid. Amazing how the Beast tames the wind. Second pack. Same. Did some pitch pumps. Tal was holding fine. Flew her around a bit. By the end of the second pack, I had to "fly" the tail. I had to keep left rudder to keep her from spinning. Not crazy, but enough. I could fly it of course, but something is wrong. When I hit throttle hold, it seemed to "release" it and the tail moved left.

I'll check the mechanical again, but I can't imagine how anything "slipped". This is basically what it was doing before on spool up. I very carefully checked out the tail, lubed the bearings slightly and rebuilt it. It is smooth as silk and the bearings are fine. Also, I pinned the boom while I was at it. This is just baffeling. Any ideas? I suspect it is something with the servo somehow, because the Beast seems fine and the tail also seems fine, otherwise I couldn't control it at all. Really crazy that it flew fine and then developed the problem again.

[chrismechanic]

oh dear..so is this with the 450 se tail on the heli ? is it the whole tail unit you have swapped over?
seems strange the way it worked ok for a while.
how long do you fly for?
are you timimg the flights?
did you get new bearings for the original grips, as you said you was going to get some boca bearings for them.

[ryem3]

I had swapped the SE tail over, but put the 450 pro tail back on. I flew each battery for at least 3 minutes. I left the old bearings in the pro grips after cleaning them and adding a drop of Scorpion motor oil on them. The tail action is perfect and the tail bearings are like butter. Smoothest tail I've ever had on a heli! Starting to wonder if it's my 9257 servo somehow. I'll check that out next.
The boom is now pinned, so I know I'm not getting a mid-flight shift in control rod distance. Guess I could rebind the system, but it is odd that it started out flying perfectly.

[chrismechanic]

i would try it with new bearings in the tail grips..seeing as so many others have had issues with them...or try a few hovers close to ground with the se tail on.
the grips could be smooth as when static..but with centrifugal force on them they could be locking up or binding..
a way to test this is to remove all blades and pop the carbon rod off the tail servo, spool up and have a feel of the grips as you push and pull on the carbon rod while they are rotating.
you will feel resistance as you force them off centre, this is normal.
chris

[ryem3]

Thanks, I'll check that out. Guess I might as well order the bearings as well. It's a cheap option anyway.
I had the same problem when I used the 450SE tail though. The thing needed a manual hold of the tail to remain centered. I don't get it.