Futaba 611 started to drift to Left

[lperagallo]

OK, So the turbine is flying great but I notice today that I seem to be correcting more and more on my rudder to fly straight across the field. I also notice that I',m working harder to keep my loops from becoming corkscrews. I go into a hover on the last flight of the day and I notice that the tail is drifting off to the left. I haven't changed a thing but the drift is definitely there.

Any suggestions on what to be looking for. Gain is at 37%. Linkage if fine. It's got a Futaba BLS251 servo that remains cool after at 10:30 flight time. Sensor is mounted with gren zeal tape. Has been all season.

Suggestion to look for please.

Lou

[Matt Jenner]

there is 2 possibilities i could think of,

Before the servo centered you have moved the hellie, this will cause drifting..

Secondly there is a feature in the Amp for adjusting the tracking, either + or -

Matt

[Peter Wales]

I have found that these gyros will drift unless they are set up mechanically first. You have to have no trim and set the pushrod up so that the tail stays still in normal mode. Then you can switch to HH mode and the drift is usually gone. I have found this problem to be particularly prevalent on scale birds with comparatively low head speeds.

[rkeith2]

I agree with Peter -

Solid mechanical setup (at hover) then make sure it initializes while still and then all should be good

[DDragon]

Hi Lou, I have the same setup as you on my turbine, and the 611 with the brushed servo on my Trex600, and I've been getting exactly the same problems on both birds. I've done everything I can think of. I use Nigel Brown's instructions as indicated. I'm pretty good setting these up now, but I still get some slight drift counter-clockwise (left).

I haven't tried setting up the tail in rate mode as suggested above (actually I'm not exactly sure how to do that?)... but if you're going to give it a try. Let me know how it goes and I'll try the same.

A number of people (including finless) said that the 611 doesn't have to be setup in rate mode first. So I don't know.:dontknow

[Matt Jenner]

to set up i normal mode is easy...

You ensure the the gyro is in Norm mode on the amp,

point the model into wind and hover, let go of the rudder and see which way the nose moves, if it moves to the left you may have lengthen the push rod a cuple of turns, or vice versa.. keep adjusting the push rod until until the hellie hovers into wind with no drift...

then land, go into the amp and switch to AVC or CMT ( if you like flying in both HH and non HH) and then fly in HH, if you have selected CMT you will have to activate HH vcia a switch on your TX...

this is the best way of doing it as it is now set mechanically...

I did not recommend it first as Lou said his rod was the right length... so i assumed he had already done this..

Matt

[Skiddz]

I don't set up my 611s in rate mode at all, but I *DO* get the mechanicals set so both my A and B limits are equal. Servo arm and pitch slider arm both get set to 90 degrees and I try to shoot for around 115-120 for both limits. Have yet to have any drift...

[Bell Bloke]

Just a quick thought here......are you sure that your tail thrust races are the correct way around? If these are wrong the tail binds as it speeds up, the nornal symtom for this is the tail slowly wagging as if the gain is too high only a much slower wag. Mind you Deron says that he is having the same problem so it's probably not that. But it's something to check maybe... Just to clarify the Century instructions thust race order on both mains and tail. The thrust race with the 'SMALLER' hole is the last to go on and the on with the slightly larger hole goes on first. So to recap the order is.......'Larger' hole first then the greased ball race then the 'Smaller' hole and then the nut or cap screw.
Good luck Lads!

[DDragon]

Just a quick thought here......are you sure that your tail thrust races are the correct way around? If these are wrong the tail binds as it speeds up, the nornal symtom for this is the tail slowly wagging as if the gain is too high only a much slower wag. Mind you Deron says that he is having the same problem so it's probably not that. But it's something to check maybe... Just to clarify the Century instructions thust race order on both mains and tail. The thrust race with the 'SMALLER' hole is the last to go on and the on with the slightly larger hole goes on first. So to recap the order is.......'Larger' hole first then the greased ball race then the 'Smaller' hole and then the nut or cap screw.
Good luck Lads!

Hi Bell,
you know... I'm really carefully whenever I'm putting the tail or main grips back together, and make sure I have the thrust races correct... but I always feel paranoid when someone brings something like this up... so I'll have to take mine apart and check it :YeaBaby:

[DDragon]

I don't set up my 611s in rate mode at all, but I *DO* get the mechanicals set so both my A and B limits are equal. Servo arm and pitch slider arm both get set to 90 degrees and I try to shoot for around 115-120 for both limits. Have yet to have any drift...

Hi Skiddz,
Yes, I make sure I do this as well. my A & B limits are both 110... I have the servo arm at 90 degrees but that only after giving it about +20 subtrim (does that matter?). I'm using a non-futaba single metal arm so I can't flip her around 180 degrees (I'm sure that would make her 90 degree at mid stick without the need for subtrim.

Need to check the pitch slider arm however...I have the conversion kit to bring the servo mounted to the upper frame... not the boom mounted servo however. So I don't know if this has any affect.

[lperagallo]

Ron,

This tail was set up by Tom Knight at IRCHA so the linkages should be fine. I guess I'll try new tape and see if that makes a difference. It has been perfect up until last flight. I checked to .ake sure I didn't put trim in by mistake, but there isn.t any. Oh well, flying season is coming to an end shortly.

Lou

[Skiddz]

Hi Skiddz,
Yes, I make sure I do this as well. my A & B limits are both 110... I have the servo arm at 90 degrees but that only after giving it about +20 subtrim (does that matter?). I'm using a non-futaba single metal arm so I can't flip her around 180 degrees (I'm sure that would make her 90 degree at mid stick without the need for subtrim.

Subtrim shouldn't matter unless it's a huge number.. I just ran home for lunch and checked the setup on both my 611s.. I've got 8 subtrim on one and 20 on the other.. You sure you don't have any trim dialed in? Also, what mode is the gyro set for??? (F3C etc...)

[Matt Jenner]

i have also found taking the machine out ofyour warm car and into the cold does affect and cause drifting, if you dont allow time for it to climatise...

it even mentions that in the instructions...

Could be a reason if all else was fine prev flight...

Matt

[DDragon]

Hi Lou,
I was playing with my gy611 yesterday on the T600 and wren/pred... while the wren/pred developed other problems, I think I solved the T600 drift... I set the FMOD to 3D and set the tracking to -10. This seemed to fix the drift.

Not sure if that would help you. I tried similar on the wren/pred and have drift to the right now (clock-wise) instead of to the left (counter-clockwise)... so it needs more fiddling.

[Coolice]

Hey Guys,

If you can avoid using the sub trim then I would suggest doing so as it allows problems to creep in.

Also the GY611 does seem to like being setup in rate mode and then flicking into heading hold mode to fly, but are you remembering to re-train the gyro's neutral position after doing so?
If not then I have seen this give a heli a slow drift issue.

To retrain the gyro's neutral position, setup the tail pushrod length in rate mode to obtain a hovering trimmed position then toggle the gain switch on your transmitter 3 times between rate & heading hold mode, ending in head hold mode. During this time the gyro's amplifier shows **** I think from memory and is storing the new neutral.

100% and above is good for travel limits, any lower and the servo can burn out quickly.
Also F3C mode is better than 3D, in the latter stops are much more aggresive and so extra strain is put on the tail and associated links. On a turbine we dont need neck breaking stops and so I'd stick to F3C.
.

[lperagallo]

All,

Thanks for all the suggestions. I will try out a few that have been stated above. I do like the quick stops as I am now doing some mild 3D with piros in them. I will double check the rate mode set up and I will check the TRK parameter. I have no trim or sub trim. Oh yeah, I'll change out the tape also.

Maybe it was a fluke, but I doubt it. I've been on the road all week missing absolutely beautiful weather in Indy so I'm sure that this weekend will probably end up being a wash out, but I'm hopeful I can get out for at least a few flights.

Lou