Hey all

Been ignoring the tail wag on my trex 500 FBL for a while now(heli's mechanically healthy), 'cos I was pretty sure it's the align gyro acting up against vibes.(Have tried all combinations of pads, spartan metal plate and gyro bondage in the past but wag seems to be very determined   )
And about fiddling with ail, ele gain on the 3g contoller-yes, been there done that too.

Recently been reading considerably on the option of increasing head speed at the lower end of the throttle curve, so as to bring down the wag. Changed my normal throttle curve from 0-25-50-75-100 to 0-45-75-90-100
This helps a bit, but don't feel it's a great idea though, except that it may be a half sick work around.

Anyone been able to nail down the trex 500 tail wag PERFECTLY yet?
Experimenting with bypassing the align tail gyro and putting my Quark in place as the last resort.

unfortunaltey i never tried the align fbl electronics and i never had any wag problems with the fbl 500... are your gain settings fine?.. want to check again on any binding.. yes you can still bypass and have the quark but the purpose of having the fbl sytem would be lost...
i have a few friends flying the align fbl electronics on their 500 esp's and they seem to be perfect and rock solid (except during hard piro stops).. i dont know if am right anwar flys a 500 fbl with align electronics (anwar pls correct me) and he might be able to throw more light on this..

Hey Sujju

Thanks for the suggestions
Putting in the quark just to make sure that the issue is the align gyro or not. Planning to stick on to the 3g itself anyway, 'cos the wag is not tremendous. Besides, I gotta put my quark back on my broken belt cp once spares arrive.

Have already checked for tail binding, blade tracking et al..nothing seemed to be out of place though (or I am missing something considering I acknowledge myself to be rather careless  )
Tried gain between the range 32 and 17 on my futaba 7c in GY mode. Didn't help a bit.
This wag is kinda there in rate mode too.


Anwar Sir, looking up to your advice...Let me know if posting a video would help.

My own 500 is non-FBL, the Align 3G system was not available when I got it (if I remember correctly).  I have zero wag !

I do have someone's 550E 3G with me as of today, I had helped setup it up earlier, and it also had zero tail wag issues.  That said, there are documented "mod"s to the Align 3G sensor system to handle vibrations better (including hot-glueing the 3 gyros inside the sensor unit).

In terms of what you have tried so far, a tail wag (horizontal wag of the tail, parallel to the ground) cannot usually be fixed by headspeed adjustment.  If that is the wag you are facing, it is usually one of these :

1.  A gain issue, which you have attempted to fix.  But this type of gain is easy to notice, as the wag is pretty fast.

2.  A mechanical issue.  This could be a binding issue, or a lack of lube issue, or a screw being loose (the last one I fixed on our field was a case where the tail blades had started coming loose, resulting in a somewhat slow, like 5 times a second, wag on the tail).

3. Gyro issues.  This can can be mounting issues, or the internal sensors being not properly fixed etc.

Now if your wag is a nose-to-tail wag (which is vertical in nature, and completely different from the horizontal wag of the tail mentioned above), then it is a headspeed issue, and throttle curve increases (or pitch decrease) should take care of it.

Post a video, if possible.  The last time someone mentioned something like this on the forum, it turned out to be small enough to be ignored (or considered "within normal limits").

Anwar, this is my video with the quark enabled and the align gyro bypassed. Please note that, when flying with the align gyro, I keep it at the same location where the quark is placed right now(and not at the top where align gyro sits now in video).



I just offset the rudder servo a bit to indicate that I'm in HH mode(centered it before take off).My gyro gain is 30%
The video section before the first landing of the heli is at 50% on midstick in the throttle curve while hovering whereas the one after first landing is at 70% on midstick. Pitch is 50% on futaba(meaning 0) for both cases(and both are normal mode, fyi ).  You don't get to see any tail wag or bob in this short video.  And this is when the quark is placed on just average quality foam tape. I wish I could've managed a better video though.

Tomorrow I will change back to my align gyro and write you a totally different story for both the throttle curves. And will see if I can get a better video in day light.

We really need to see the Align video, to take this forward.  But the Quark does provide the baseline in terms of how it should be !

Yes of course Anwar, I will do the align video today and post. Didn't get time yesterday for resetup of the align

Here comes the video with the align gyro. Anwar, yes it is a bob and not a wag.Excuse me when the video goes out of perspective, I sat my cam on a chair and took the video..
 


The first section before the second landing(when the rotor stops spinning) is at 50% (at midstick) on the throttle curve in normal mode.
Second section(after the second landing) is at 75%(at midstick) on the throttle curve in normal.

Both tests seem to bob the tail almost at same amplitude though the higher head speed helps a tad. The 3g sensor is kept snug enough(when i try to nudge the sensor with hand, the heli moves as a whole)

Can you keep the sensor unit of the 3G system at the top, behind the anti-rotation guide ?  Also try reducing the elevator gain in the 3G sensor, by turning the pot on the FBL controller unit.

I had tried these Anwar

Results were unfortunate

Keeping sensor at the top increased the bob further.
Had tried it in the receiver tray at the bottom as well. Didn't help.

Fiddled with various elevator gains from 9 through 12 o'clock as well. Sadly, the bob stays no matter what until i switch to my beloved quark.

(Btw, gyro gain is currently at 30%. Changing that also doesn't help tho it's for the wag)

Maybe something is amiss(and I can't find anything) in my mechanical setup that's causing too much body vibes that align cannot handle? I mean the quark is a smart gyro and it might be doing extra work to keep the heli steady. God forbid that might overheat quark to eventual death?(nyway, I'm not keeping my quark on it cos it's for the belt cp). I checked again and again to make sure all screws are tight enuf, all wires are routed well with nothing stikin out, loctite's in place wherever required, lubes are fine everywhere, no binding on tail...phew I'm out!

The important thing is that this is not a tail wag.  So a change to a gyro (Quark) that only affects the tail (and controls the drift in an axis perpendicular to the wag we are seeing now) should not affect what is going on. It does not look like it is mechanical, it should have shown up in all cases, if that was the case.

The issue is elevator wag (for lack of a better term).  And it does not look like it is a low throttle (curve) issue.  So it looks like a sensor issue, or a sensor mounting issue.

BTW, I do see that the wag has almost disappeared at times, which makes me wonder if ground effects are a factor.  Have you hovered outside, at above 5 feet or higher ?

do u have the latest software?

or is it 1 of the older units?

have u tried to strap the gyro with some velcro strap or only used double sided tape?

have u checked for vibrations like spool up with no main blades and tail control rod disconnected  and tail blades mounted?

The logic in your thought convinces me.
But, if that was a probability, I should've got the same response while bypassing the align gyro with the quark right? (unless the quark indirectly corrects for the ele wag(assuming ele wag in turn causes tail to shake)) I mean the elevator control is still with the align controller, I only bypassed the align tail gyro. Thinking about what you said, I don't understand why the quark is able to absorb the anomalies or why heli should hold well with the quark. The positioning, wiring, mech setup, controller setup and Tx setup are all the same. Interestingly it started off solid, the moment quark was put on.


Also, similar analogy for ground effects and downwash. Heli is solid with the quark even when close to the ground.  Besides I tried it at about 5.5 feet inside and it is same. Can't catch the video for lack of a good resting position for my cam at such height except my shoulders(if it's not another way of saying I stand at 6 feet  )
And doing that, I wouldn't like to drop my cam to save my heli  >

Will still try outside, when it ain't that windy. And will try tweaking the ele gain again, but wondering why the quark doesn't act up with the same gain..beats me..beats me a second time when I think of thinning down my wallet again for a Beast X or a mikado mini v.

@clayboy

S/w:v2.1
Velcro: Tried with and without(and at various tightness)

Yet to try spool up without main blades. Will do that and let you know.


Thanks

if u get like razor like vibes try without tail blades and check if vibes goes away, fbl do not like razor kind of vibes ,

also tight gear mesh to motor can make vibes that gyro not like, should normally not b a problem but if u got a sensor that is a bit sensetive,

if u cant get it working maybe a faulty sensor? maybe u can borrow a sensor from some 1
 

I remember Reading a long time ago people had problem with lose sensors in the 3g and used hot glue to fix the sensors. beleve that is the way align do it as well on the new units. if u can't get it working maybe it would b a idea to open it up and hot glue them. align have no warrenty anyway

Well, there's some progress

Arrested some bad vibes today.
Probably the fast twitch in my tail was due to an ever so slight bent in the tail boom!
I pulled out the boom and rolled it on the floor; noticed unevenness.
I assume the bent was caused due to considerable flying after installation of a third party horizontal carbon stabiliser which didn't have the trapezoidal cut in its midsection(the cut actually seats the boom properly). The uneven force caused hereby towards one direction, should've got the boom bent. See no other reason, though this may not be one strong enough.
Replaced the stabiliser with align stab(was saving it for fear of crashes, jees what a miser I am  ) and put in a new tail boom also.
Thinking of upgrading to a carbon fibre boom as well later.

After installing the align stab and new boom, the vibes and the fast twitch(razor vibes) in the tail stopped;
and with elevator setting still at 12:00 o'clock and 70% headspeed at midstick, the tail bob(the vertical motion) vanished. Hoping the 70% headspeed is okay at midstick.

Sadly the wag(horizontal) still remains like it has been(yes, fiddled with the gain)
Yet to completely demystify the wag! Could be a 3g sensor issue after all.

Thanks Anwar, Clayboy..will post updates with videos. Meanwhile any other suggestions?

if the vibes are totally gone i would do a bench test again but dislocate the servo from the push rod this time spool up and pull it back and forward to feel so the tail doesent bind.

aligns softstart is good so i would go 0-70-80 -90-100.

if the tail servo is up to scratch i would open the 3g unit and hot glue the sensors, if there is no vibes or no binding and a fast servo it should not wag horizontal with a properly working gyro.

u can put a piece of tape from the side of the wall to the sensor and dot a bit of hotglue to make it solid, if a sensor is slightly loose it will do strange things and it has been problem with the 3g before with loose sensors

See the whole complication is that the heli is well behaved with the Spartan, in terms of the vertical wag (I can see how the Spartan fixes the horizontal tail wag, but NOT the vertical wag!).

In any case, doing the sensor mod (hot glue or silicone) seems like a good idea !

could b the control loop. control loop is not compleate if 1 sensor is disconnected sins ail and elevatot sensor have no clue what the spartan is doing, when connected if loose i guess it can make funny things, but i am only guessing, i have never used a 3g nor fiddle around with it

Yes, I guess it has to be the sensor. Posting a video here after the tail and stab replacement.


You would see it behaving much better. Unfortunately the horiz wag is not visible in this video though it can be seen with naked eyes, maybe I will try to take another video from the rear to see if it can be captured.


Anwar, you meant vertical wag ?(or more accurately termed bob).

@Clayboy: I've ordered a Futaba S9254 to see if it holds the tail better than the align DS520. And I've ensured there's no binding in tail.

Yes, I meant vertical wag... corrected

This flight can be considered as normal (from the video alone).  If there is slight horizontal wag, that would not be visible in other types of flying (ie, other than hovering).

In any case, practically everyone is doing the hot glue mod on the Align 3G sensors.

Yes, when I do pitch pumping, I don't see the wag. Anything fast, don't see the wag.
But I am obsessed or posessed or watchamacallit; just can't live with the wag at hover 

So it practically comes down to "shoot it down with the glue gun"; oh well  why did align make such a bad donut!

So here's a picture of my 3g sensor's underbelly...

And guess what, align's already shod the sensors and connector in epoxy(guess it is missing on one sensor though). So that mod is now out of the question  
Maybe I will try some Zeal contacting all three sensors as well

Is putting in some chewed wrigley spear mint gum a bad idea? (At least I can remove it if things don't work out) Also, the gyro would smell good 

Hey, is it a Mikado mini V buzzing in my ears  

Hmmm... don't see why the mod is out of question.  Have you seen the pictures of some of them with the mod, they have shoved in quite a bit of hotglue/silicone !

http://www.google.com/images?hl=en&q=align+3g+sensor+mod&biw=1431&bih=710