Maiden not so good...

[warpspeed]

I finally finished setting up the head at around 1am and just HAD to head out to spool her up, even though it was all of 20 degrees outside and half the lights in the garage don't work when it's that cold. My intention was to just hover and make sure the blades were tracking, so I slowly spooled her up and hey how about that the soft start works really well on this esc! This thing takes almost as long as my 600 to get up to speed. And speaking of speed, while I didn't tach it the headspeed sounds WAY high-and I'm running the smaller of the two pinions. Anyway, she's light on the skids so up we go-or maybe not. An inch off the ground the tail starts jerking around. Not a wag, more like a twitch. BAD. Put her down, unplugged, spent a half hour out there freezing my ass off only to find nothing apparently wrong. How could there be anything wrong? This is a brand NEW heli, never before subjected to my dumb thumbs! The build went perfect, in fact I was amazed at just how smooooooth everything worked, she ought to be just hanging there in front of my face waiting for me tell her what to do! Went through the radio settings just to make sure, noticed gain was set at 30. Not sure how that happened but for giggles cranked it up to 75. This allowed me to get her off the ground, but only for a few seconds-damn thing was twitching and jerking around like an epileptic receiving shock therapy. I've ignored the "Tail Problem..." post because I was just SURE this baby would have no issues, but I read the whole thing before posting so I'll pull the tail apart (again) and see what's what.
Couple of observations-somebody here mentioned cyclic was slow. Obviously a short hop in the garage is not representative of what this heli's capable of, but it seemed EXTREMELY quick to me! In fact it behaved more like a micro, (Blade CP/HB King) SUPER quick to respond to the slightest stick input. Mine came with a set of Sab 430's that weigh in at 60 grams ea., I wonder if that has anything to do with it. They almost seem TOO light. (BTW, there's a note in the box that claims these blades are good up to 2000 rpm. Don't know WHAT she's spinning at, but it sure sounds like way more than that! Am I playing with fire here?)
Also, the FP 3300 balances mine perfectly-until you have to move it down the tray to get the stupid canopy on. Yes folks, everything you've read is true-that sucker just plain doesn't fit. I don't care for the 'grub screw into the ARB' idea that much anyway so I'm just going to drill holes a bit forward and install the canopy mounts with their own screws, ala the 450/600.

So, let's just say I'm semi-impressed. The size is right and she IS a good looking heli, but Align omitted one little thing when they printed up the box-three little words that should be right there under the glaring "3D Performance" logo.........

Tail by Walkera!

[ckoelliker]

It sounds like a glitch to me. What is your radio set up, and where do you have your electronics placed. My tail glitched for my first flight. I moved the gyro, but to no avail. I then switched the gyro tape, and that took care of it. That is a complete long shot, but I guess my point is that there is a lot of things that can make your rudder servo twitchy.

[warpspeed]

It does seem like a radio glitch, rather than something mechanical. I've got the 401 on top as far from the bearing as possible, stuck on with the tape supplied by Futaba. Same setup as my 600 basically, although I'll admit I wasn't as anal about the wiring so it's all zipped together in a loose ball stuffed between the frames. I did not let the gyro acclimate to the cold weather-wonder if that might have something to do with it?

[skeppley]

Try replacing the thrust bearings in the tail with radial bearings. Bring the gyro gain down to 50 or so, and see what happens.
It only takes a few minutes to swap out the bearings, and if it helps, you'll be a happy camper :)

[warpspeed]

I suspect you may be right. When I pulled the tail apart during the build to check for loctite the innermost race was stuck in the grip-at the time I didn't think it was a big deal since that's where the race is going to stay anyway, but I'll give the radial bearings a shot. Time to break out the calipers!

[Finless]

Even though the gyro is back as far as you can get it the same bearing noise that effects the gyro can get in through the gyro wires and do the same thing. As a test, unbundle the gyro wires from the servo wires etc and pull them out of there and temporarly tie wrap them to the boom supports or something.
Anyway your description sounds like noise to me!

Bob

[ckoelliker]

A little off topic, but has anyone tried running a ferrite ring on the gyro wire?

[thedrill]

Warpspeed:
You said that it was 20 degrees out that is -6 celseus. thoperating range of the 401 -10c to +45c. That is14f to 113f maybe too cold ?? I have had the 401 go down in high temps. just a thought

[fogger]

Damn, at this point my whole plan to get a 500 this year may be predicated on QuickUK building a tail for the heli... I just can't see going backwards to fight with the align tail issues.

-Fog

[warpspeed]

Look at it this way, Fogger...People will think you're an expert at those 'crack' moves!:YeaBaby:
Anyway, if I don't figure this out, SOMEONE here on the 'Freak will, then we'll all be able to apply the simple five minute fix and be on our merry ways.

Ok. Moved all the gyro wiring out of the frames away from the servo wires and step-down. I just loosely zipped it to the skids to keep it away from everything. i also noticed the wire to the remote Rx was running across the step-down, so I re-routed it out and away. Back out in the garage, (its 40 now-gol'dang heatwave!) and sorry to say, no real difference. BUT, maybe this will ring a bell-with no rudder input, or very very small, slow rudder stick movements, the tail behaves normally. Anything even slightly more aggressive and the epileptic twitch returns. So I think radio glitches can be ruled out. I'm going to tear the tail rotor apart again and see what's up, will let you know if I find anything.

Thanks for your help guys...keep it coming!

[skeppley]

Did you swap the bearings when you tried that stuff?

[warpspeed]

Nope-was trying to rule out radio trouble first. But it's beginning to look like you may be right. Thing is, I don't think I have any bearings that are the right size. I'm going thru my pile of spares now but so far no good. I'll have to measure everything and then PRAY the lhs has 'em in stock.
I may try grinding down the inner race first......

[HeliBurns]

I have read where, when moving from one temp. to another, like from inside 75 deg. to outside -10 deg, the gyro needs time to temp. stabilize in the extreme cold.

[kster]

I too have just maidened my rex 500 this morning. I had a tail wag back and forth at any headspeed. I reduced my gain down to 40 and wag went away. Did some easy punch-outs and tail held great. I am still breaking in the packs so wanted to take it easy. I will try more later today. I am running 401/9257 AR7000 with DX7. Stock ESC set to 6V with 5.1 step down for tail servo. I will try another test flight as I didn't lower the gain till the end of the flight. It dis seem to help though.

I will repost my finding later today,

kster

[iwasaseabee]

Do the control links move freely in the tail pitch slider? I had to free mine up a little by sanding the edges. make sure yor settings on the gyro are set for the correct type of servo digital or non digital I have the limit on mine at 125. I'm running a 401 and 9257 with gain at 54% my tail is rock solid! I've been flying between 20f - 60f. Good luck.

[fogger]

The large temperature change generally induces drift, not wagging or kicking out. Piezo based gyros are more prone to this effect than the smm ring type (MEMS) gyros.

-Fog

[warpspeed]

Ok guys, another test hover and still the same crap. There is something seriously wrong with this thing and it is most definitely unsafe. Now before somebody shouts 'n00b' or 'setup' this is NOT the first heli I've built. Like every other bird, I took my time and made sure it was done RIGHT-mainly because I hate re-doing wiring.:lol: Everything is smooth as butter, nothing binds. Now, I'm not disinclined to believe it isn't a radio problem, as I've had my fair share of problems with Spektrum's junk, but the more I dick around with it the more I've been able to narrow down the circumstances when the problem appears. I haven't been able to follow Skeppley's advice as naturally, my lhs does not have the correct size bearings to convert over to a radial setup. I have ground the innermost races down, but they are still snug so I'll have to grind them down more to see if it helps. Anyway, I'll try to describe what happens, and maybe one of you will recognize what's going on. If I can get video tomorrow I'll post it, but basically it LOOKS like radio glitches.
As long as I don't touch the rudder, the tail behaves fine. If I lift off and just use cyclic to keep her in place, the tail behaves fine. If I slowly apply left or right rudder once in a hover, and I mean s-l-o-w-l-y, the tail behaves fine. If I turn the rudder to one side or the other in a normal fashion, it jerks like a radio glitch. If I 'pop' it into a hover it jerks like a radio glitch. If I hammer the throttle (tough to do in the garage) it jerks like a radio glitch. Obviously if it were radio or noise trouble it would be apparent all the time-not just under certain select conditions. I suppose it could be a bad tail servo, faltering under load, even though on the bench it doesn't exhibit any issues. Same with the gyro-the heli doesn't spin wildly out of control without any rudder input. It's doing it's job just fine. Short of the bearings swap I'm starting to run out of ideas. And if you haven't noticed, this is really starting to piss me off-so please excuse the tone of this post and understand I mean no offense. I do appreciate all the help.

Are you guys familiar with the term "FM"? I mean, there's nothing 'wrong' with the thing, it just doesn't work! :arggg::arggg:
I'm stumped.

[ckoelliker]

Mine only glitched when I increased the collective. I think at those times the gyro can pick increased radio noise from the motor, bearings, etc. It still sounds like a glitch to me.

[erniefritz]

Align omitted one little thing when they printed up the box-three little words that should be right there under the glaring "3D Performance" logo.........

Tail by Walkera!

maybe it should read "only for competent builders & pilots" Just kidding :)

Did you check to make sure your tail is rotating the correct way? or the belt might be twisted in the boom... The belt should be run on the tight side....

[Pinecone]

Controls free, no binding?

Bad tail servo?

[warpspeed]

maybe it should read "only for competent builders & pilots"

That was totally uncalled for. thank you.

[erniefritz]

So was " Tail by Walkera"

[warpspeed]

As you can see, I caught your post before you added the "just kidding", as I obviously was about the tail being made by Walkera.
Anyway it's fine by me if you doubt my competence-and if it turns out I've done something incorrectly I will own up to it.
Just for the record, I've now built six helicopters all by my lil own self, and with the exception of the 500 every one has flown perfectly without issue first time out.

[erniefritz]

Sounds like your pretty competent to me , I'm not doubting you , I've got a lot of builds under my belt too, I just want to see you get that thing in the air without the tail glitching ...

I've seen the symptoms before but that was on a machine that had the belt twisted the wrong way and had an extra twist in the belt. If it's not Mechanical , then obviously it's going to be an electrical component going like your tail servo or Gyro...

Hope you figure it out...

[warpspeed]

Thanks Ernie. Didn't mean to sound like such a jackass but it's really frustrating. I know with everyone's help here I'll get it straightened out eventually.

Controls free, no binding?

Bad tail servo?

Yup, everythings as smooth as a baby's bottom. I think the servo is ok-I just put it on the 600 and the tail behaved ok, but the pack was dead so it was a very short hover. P'cone, I know you're going to disagree w/me over this, but I'm beginning to suspect a faulty rx. I've got a spare AR6200 destined for a plank that I am in the process of swapping as we speak, so I'll know for sure in a minute. If that doesn't do it then I'm stuck until I can get my hands on the right size bearings to try the skep-man's idea.
It's too bad parts aren't widely available yet-otherwise I'd just swap the whole thing out.