Tail Drift using 611

[Rotorworkz]

Question hopefully Im specific enough
I maiden my New Stratus today with a 611 and it has a slow drift. Nose moves left in all 4 points of wind direction. It is slow in a hover but drifts faster in fast Fwd flight. no change in drift speed stays constant even at different head speeds

my set up is
9C
Gyro Sens=
mode: GY
mix: Act
NORM,IDL1&2 are all at AVC 50% (for intl starting point)

I tried raising my gain but that didn't fix it and being Im completely unfamiliar with this gyro / heli Im at a loss
any help would be Great appreciated!
My other nitro and electric heli's all have 401's which is rather simple and straight fwd.........

thanks

Charley

[WillJames]

You should be runnign about 36-37% gain on teh 611.

This happens most of the time from not having your heli completely still when you first turn it on and the Gyro initializes. I would bet it will not do it net time you turn on the heli. You have got to keep the heli absolutely still during the first about 10 seconds after turning it on, or you will get drift just like you describe almost every time.

[Rotorworkz]

You should be runnign about 36-37% gain on teh 611.

This happens most of the time from not having your heli completely still when you first turn it on and the Gyro initializes. I would bet it will not do it net time you turn on the heli. You have got to keep the heli absolutely still during the first about 10 seconds after turning it on, or you will get drift just like you describe almost every time.

Ok Great my 50% was just for intl first flights I will reset the Gain to what you recommended and try it.

As for keeping it still I thought I was keeping it absolultly still. Is it anymore sensitive about movment than 401? I follow what you are saying but I don't know how much more on the still side I can get it.

[WillJames]

Somwtimes it happens. When it does, what I do is a) Hold the rotor hear tightly and switch off the RX then switch it back on and let the gyro re-initialize while holding it as still as possible or b) Take it out of heading hold nad fly it around for a couple of minutes in normal then put it back in HH and usually the drift has stopped, if not I do procedure a.

[TerryBelanger]

Not having enough dampning or Vice Versa can also cause the drift. Are you using the metal plate and 2 strips of the double sided tape (DST) that came with the 611?

I put a peice of DST on the back of the sensor, then the metal plate, then another peice of DST and then attach it to the top shelf on the Stratus. Mine drifted at first and got better once the engine broke in and tuned. I replaced the bottom peice of tape with a little bit thicker DST and the drift went away.

[SteveL]

He was not using the metal plate thanks Terry

Will I was out with Charley and he was being anal about not moving after he first noticed the drift. When you move a 401 I know you can see it in your tail before you even lift off. The tail will slowly creep. I don't know about the 611 but I installed one at the same time and had no trouble. I used the really thick tape from CSM. I don't like the Futaba tape I have had it let go after only a few weeks.

What are you guys using for tape?

Thanks for the advice.

[DavidH]

The metal plates that comes with the GY502, 601 , 611 is really only nessecary if the sensor is being mounted on a carbon fiber plate. I have not used the metal plates when mounting the sensor directly onto a metal or plastic surface and not had any problems. I use 3M Products 4408 double sided vinyl foam tape. I have not used the Futaba foam squares since the G 501 came on the market in early 94.
I also had problems with the Futaba foam squares breaking down and allowing the gyro to turn loose.

You also might try relocating the sensor to a different location. That may stop the drift. Also have you told the gyro to have the same neutral between AVCS and Normal mode. You do this by flipping the switch back and forth three times real fast between AVCS and Normal mode.

David

[WillJames]

I use the 3M Clear tape in 3 layers, or Zeal Tape, or the 3M foam that David mentioned above depending on what I can get at the time. ALso I use a Velcro strap to pretty tightly hod it down after installing it. Don't be afraid to get the velcro pretty tight. Did you guys set the mechanical linkage out of heading hold? Sometimes that makes a difference as well. I know a lot of people these days don't do it, but I always do. Seems to make the overall performance of the gyro better and keeps the tail servo happy IMHO... but you know how Opinions are...

Yes the 601/611 will get the same slow drift like the 401 if you move it during initialization sometimes.

[lakespinner2]

I've had really good luck with that Zeal Tape, it solved a slow gyro drifting problem on my gasser with a 601 and a glow bird with a 401. I've seen it eliminate drifting problems on 3 other helis that had drifting tails. I'm sold on it but now I can't seem to find the stuff. I'm down to my last pack of it and I'll have to start rationing it soon. Is it available anywhere these days ? If not, what's the best substitute ? thanks

[WillJames]

I'm down to my last pack of it and I'll have to start a rationing it soon



Me to! I bought 3 packs from a LHS and now I need more to. Gave away one pack, used one pack and now geting about 1/2 way through the last pack I have!! If you find more than you need somewhere, please let me know where on the sly. ;)

[Rotorworkz]

I added the metal plate and plenty of tape gyro sets about 1/4" off the mount base plate on Stratus. Gyro padding seems nice not to stiff or spongy

Test hovered again and still no Joy......... I did notice this time that Head speed does effect how fast the drift is
Normal mode is little to no drift
Idle (1) 1700rpm HS moves about 2-4 inches every 10 sec.
Idle (2) 1850rpm HS moves about 5-7 inches every 10 sec.

I could try to relocate it but where.... Stratus doesn't have lots of space

any other Ideas :?

thanks

[WillJames]

When the tail is spinning faster or slower the drift should change as you state it does.

Do you have any subtrim or trim on the Rudder channel? Did you setup your mechanical linkage in Normal mode so it is neutral in hover?

Do you know someone with another sensor you can try if the above is done and there is no trim or subtrim?

[Rotorworkz]

When the tail is spinning faster or slower the drift should change as you state it does.

Do you have any subtrim or trim on the Rudder channel? Did you setup your mechanical linkage in Normal mode so it is neutral in hover?

Do you know someone with another sensor you can try if the above is done and there is no trim or subtrim?

I have no trims in rudder with pre set sub trims and stick trims.
As for mechanical linkage when I turn on the Heli My TR blades initialize to Zero pitch

also yes SteveL has a 611 maybe I can talk him into a test ride

thanks

[capebob]

I don't have much to add except one thing that hasn't been mentioned. I think everyone has assumed that you don't have any revo mix. By default the 9C has revo enabled and has 20% revo revo mix set into the program. Just a thought.

Bob

[Rotorworkz]

I don't have much to add except one thing that hasn't been mentioned. I think everyone has assumed that you don't have any revo mix. By default the 9C has revo enabled and has 20% revo revo mix set into the program. Just a thought.

Bob

Thanks for the input Bob I have turned that off (Been nabed by that one before :D )

[WillJames]

As Bob said, revo mix could definitely be your issue! Should have caught that earlier, sorry.


Your tail blades should not be a 0 degrees when the gyro initializes. There has got to be enough pitch in them to counteract the main rotor rotation. What brand of heli is this? forgive me if you have already said.

[Rotorworkz]

As Bob said, revo mix could definitely be your issue! Should have caught that earlier, sorry.


Your tail blades should not be a 0 degrees when the gyro initializes. There has got to be enough pitch in them to counteract the main rotor rotation. What brand of heli is this? forgive me if you have already said.

Yes Revo could do it but it is disabled. I originally started with about 2-3 degree of pitch in TR but later during this tail drift issue I removed it as for heli type it is a MA Stratus my latest addition to the fleet Merry Christmas to me :D

[WillJames]

On the stratus, the pitch control arm should be parallel with the bracket that it is mounted to as a start. This will be very close to right on.

If you stand above it the black plastic pitch control arm should be difectly below the aluminum machined bracket it is screwed to. I can take a pic if you need.

Do you know someone with a spare sensor that you know works? Plug it in take it on and try it just for kicks.

[capebob]

You really need quite a bit of pitch with the tail rotor bell crank at 90 degrees I'm not sure how many degrees, but you should have about 7-8mm of tail rotor shaft showing between the gear case and the pitch ring (slider). Also, make sure that you have the M10 x 2 bolts screwed into the proper hole in the tail rotor grip. You should use the hole that is closest to the round end and not the one that is directly in the center.

Or you gyro could be broke. :shock:

Bob

[Rotorworkz]

Thanks I will look at those items too next will be borrow Steve's sensor

[Bert Kammerer]

Don't know if you fixed your issue yet, but I had the exact same issue for weeks. Even though my issue was not directly related to engine vibration, I hear that often times a gyro drift is an indication of high frequency vibration. Make sure your fan is statically balanced and that you have it dialed in correctly. You should have the least amount of run-out on it. I have found that for the Stratus less than 1 thou run-out is optimal.

I have been using a combination of the CSM gyro tape that comes in little strips (three strips together) and the 3M tape. It seems to work exceptionally well with no drift.

I have also seen and heard and many people stop the drift by relocating the gyro to the underside of the battery tray. Some other people have moved the tail servo to the boom and have made a little plate in the hole that holds the tail servo to mount the gyro. All these options will more than likely stop the drift, but you are going to be masking a problem instead of fixing it.

Good luck :)

[SteveL]

He went with 3M 4011 tape and it seems to be fine now. I am guessing it is his engine being really rich (brand new C-spec) causing it. I think he used 2 layers of tape plate then 2 more layers. That tape is really thin but seems to work well. Now we just have to wait nad see how it holds up (good I hope I just bought some).

[Bert Kammerer]

Thanks for the update Steve. I use a layer of the outdoor 3M tape, which is very thin, then three strips of the CSM gyro tape, then another layer of 3M tape and then the gyro. Some people think it is too much tape, but it works very well for me. I also experienced this drift issue and took most of the heli apart looking for bad bearings as source of vibration, also pulled the fan out, rebalanced it, dialed it back into the engine, etc. The drift never went away until I discarded the Futaba tape.