GY401 - Gain? Is too low as bad as too high?

[jonp]

I have a 450V2 a 500ESP and now a 600ESP all using GY401 gyros. On the 500 and 600 I notice that when spooling up on the ground the tail shakes as the ESC meets the throttle curve set points, so I turned the gain down.

(The 450 & 500 use a 9257 and the 600 has a 9254. I don't have any issues with the 450 tail)

On both the 500 and 600 I have been flying with about 50% gain on the 401. I notice that after a couple of minutes the gyro loses it's lock and drifts off centre a little bit. So I land and notice that the red LED on the gyro has started flashing. (always solid when taking off).

The 600 is very new (just a dozen or so flights) and after a couple of minutes I get a tail shake that won't stop - so I have to quickly land.

As I said - the reason I have the gain down at about 50% is because of shake on spooling up but today I tried turning the gain up.

My 500 seems LOCKED in at about 65% and during the flight the tail remained locked in and when I landed I had a solid LED. If I go much above 65% it seems that the heli almost bends in half when the tail stops! 65% seems to work great for my 500.

My 600 I have turned the gain up to 80% (85% is too much). I noticed that setting the gain anywhere between about 50 & 75% that the tail would shake after a couple of minutes of flight.

I have two questions -

1. Has anyone else noticed that if the gain is too low that the gyro will drift off centre and the LED on the gyro will start flashing while flying?

2. If the gyro gain is too low it can that cause the tail to wag - in a similar way to having the gain too high?

I always thought that too much gain causes tail wag and too little gain simply does not hold the tail so well.

(I am using the same radio gear for all my models - Airtronics RDS8000 2.4)

Thank you so much in anticipation of any advice / guidance! Of all the questions I have asked this is the 'issue' that has given me the most trouble!

[Bob O]

Not sure if this is what you're looking for, but 50% gain is basically not providing any "holding" power at all. That would explain why your 500 is "LOCKED" since you've increased the gain to 65%.

From my understanding and experience, you should shoot for a good hold without wag in the 70 to 80% gain range. If you can't get the tail to hold past say 85%, then you should move the ball out on the servo arm. If you get the tail to hold with a super low gain, say 60% or lower, or can't get rid of wag even with a low gain setting, you should move the ball in on the servo arm.

Others will chime in I'm sure.

Hope this helps a little.

[jonp]

Thanks for your reply. The servo horn length I am using is determined by a) the advice of others and b) a limit setting of about 90% on the limit pot on the gyro as per the Bob Finless videos.

The 500 seems well locked in, as does the 600 but my concern with the 600 is that the tail wags below 75% and above 85%. I have only flown it a couple of times since finding this 'sweet spot' so I have not ruled out that it is now resolved. Since this heli is new I still have those suspicions that something else could be wrong (you know how it is?)

I just didn't know that a tail could wag with too little gain the same as with too high a gain setting?

[jt41time]

Vibrations? You said that this bird is new... Check to make sure the is zero vib. That would make that gyro be all whacked out. I exp this with my 450. Very sens to vib. And make sure there is zero play and zero bind in the tail rod setup. 90 on the limit sounds like you have a goot servo ball spot. If the servo isnt fast enough, it will wag. With the larger bird, you will need a good servo. Fast dig servo. Using any weight mod? That for surly helped me... Less load on the tail. Good tail blades also. The kbb blades helped alot. I had a big vib from my tail and all it took was a 1/4" x 1/4" black tape and it was smoth as hell. Stopped all my probs with the tail. It took alot of time and alot of effort but now, perfect. Rock solid. I did a carbon rod for my tail and it eliminates all binding in the tail. I used a trainign gear set from an old heli and made one.

[jonp]

Originally Posted by jt41time

Vibrations? You said that this bird is new... Check to make sure the is zero vib. That would make that gyro be all whacked out. I exp this with my 450. Very sens to vib. And make sure there is zero play and zero bind in the tail rod setup. 90 on the limit sounds like you have a goot servo ball spot. If the servo isnt fast enough, it will wag. With the larger bird, you will need a good servo. Fast dig servo. Using any weight mod? That for surly helped me... Less load on the tail. Good tail blades also. The kbb blades helped alot. I had a big vib from my tail and all it took was a 1/4" x 1/4" black tape and it was smoth as hell. Stopped all my probs with the tail. It took alot of time and alot of effort but now, perfect. Rock solid. I did a carbon rod for my tail and it eliminates all binding in the tail. I used a trainign gear set from an old heli and made one.

Very smooth, main and tail blades balanced, 9254 servo is very fast, tail properly set up with no binding.

[jt41time]

Try a weight mod. I just used SS balls one longer screws for mine. Cheap and easy. I dont how much weight you would need for a 600 tail though...

[jt41time]

try more HS.

[jonp]

Originally Posted by jt41time

try more HS.

I am running a flat curve of 100% - loads of power. Thanks for you input but can I ask are you speaking from experience of a 600?

[jt41time]

Some. But there common problems cause they are they same design and ur using the same electronics. Have you tried to switch out thr gyro from the 600 from the 500? eliminate... Sorry bro, just trying to help. sometimes the little things are the problems

[Old Sloppy]

Originally Posted by jonp

I am running a flat curve of 100% - loads of power. Thanks for you input but can I ask are you speaking from experience of a 600?

I speak from experiance of my 600e.

My headspeed is set to 1800 rpm, I have no wag at all.

weight mods are not needed nor do I have any. (for extreme fine tuning only)

Futaba 9254 servo.

You do want your tail servo ball fairly close to the servo case (aprox 11 mm arm length).

My 401 limit is 115 and delay is zero.

My transmitter is Futaba so my gain % may not be helpfull to you.

Too low of a gain just makes the tail "loose" (kind of wanders)


Harry

[jonp]

mistake

[jonp]

Originally Posted by Old Sloppy

I speak from experiance of my 600e.

My headspeed is set to 1800 rpm, I have no wag at all.

weight mods are not needed nor do I have any. (for extreme fine tuning only)

Futaba 9254 servo.

You do want your tail servo ball fairly close to the servo case (aprox 11 mm arm length).

My 401 limit is 115 and delay is zero.

My transmitter is Futaba so my gain % may not be helpfull to you.

Too low of a gain just makes the tail "loose" (kind of wanders)


Harry

I guess I have the ball one hole further out which gives a limit setting on the gyro of about 90%. Regarding having the gain too low I would have thought that, as you describe, it would result in a loose tail.

[jonp]

Looking into this even further I have now noticed that the LED will start to flash after a couple of minutes without even taking off.......I checked all three of my helis last night and they all do it!!!!

So, no motors running, just sitting on the bench, fiddle with the sticks for a couple of minutes and the LED starts to flash. A click of left rudder trim and the LED is solid again - play with the sticks another couple of minutes and it flashes again! If I leave it for several minutes it takes two clicks of left rudder trim to make the LED solid again.

Maybe the Transmitter is sending a slightly 'off' signal to the rudder channel?

[ollie2893]

Originally Posted by jonp

I have been flying with about 50% gain on the 401. I notice that after a couple of minutes the gyro loses it's lock and drifts off centre a little bit. So I land and notice that the red LED on the gyro has started flashing. (always solid when taking off).

What Tx is this?

Originally Posted by jonp

Looking into this even further I have now noticed that the LED will start to flash after a couple of minutes without even taking off

I fly this gyro on a JR radio. From memory, steady LED signals HH mode; flashing LED means YR mode. On a JR radio with a continuous one-sided gyro gain channel from 0% to 100%, 50% is actually gyro dead-band. Anything below will be the gain for YR, anything above HH.

All that you describe (aside from the LED changing from solid to flashing) is consistent with a 401 in YR mode and a tail that isn't mechanically trimmed.

[jonp]

Originally Posted by ollie2893

What Tx is this?

I fly this gyro on a JR radio. From memory, steady LED signals HH mode; flashing LED means YR mode. On a JR radio with a continuous one-sided gyro gain channel from 0% to 100%, 50% is actually gyro dead-band. Anything below will be the gain for YR, anything above HH.

All that you describe (aside from the LED changing from solid to flashing) is consistent with a 401 in YR mode and a tail that isn't mechanically trimmed.

Hello Olie - it's an Aitronics RDS8000. Gyro control is -100% to 100%. Zero in the middle.

If I turn the heli on, solid LED on the gyro and then don't touch anything within about 5 or 6 minutes the LED starts to flash.

[jt41time]

If that gyro blinks, then its getting a movement from your tx. or thinkning it is. switch one out from another hel and see if it doing it.... Eliminate it. If the other one does it, then its a tx/rx problem sending in ifo to it to move. If your using the same tx on all your helis with the gyro, then mabe its the gyro or the rx. switch out everything.

[ollie2893]

Yes, I did remember the LED incorrectly. Here's the relevant portion from my manual:

Rapid flash
Displayed while data is being initialized at power ON.

Steady light
Indicates that the gyro is operating in the AVCS mode.

Off
Indicates that the power is OFF, or the gyro is operating in the normal gyro mode.

Slow flash
Displayed when there are no rudder operation signal being input from the transmitter. At this time, the rudder servo does not operate.

Intermittent flash
Alarm display when the power was turned on in the normal gyro mode. For the rudder neutral signal to be read correctly, set the transmitter to the AVCS mode and turn on the gyro power again.

Double flash
Displayed when the rudder signal from the transmitter in the AVCS mode is different from the neutral signal memorized in the gyro. Also flashes when the rudder stick was operated.

Single flash
Displayed only when the transmitter sensitivity switch is rapidly switched between the normal and AVCS positions at least 3 times, then returned to the AVCS position and
the transmitter rudder stick was rapidly moved to the left and right at least 3 times. After this display goes off, the rudder is in the neutral position.

jt41time: switch one out from another hel and see if it doing it....
jonp: I checked all three of my helis last night and they all do it!!!!

The common denominator between all these three gyros is the Tx. If your LED flashes slowly, then, according to the manual, the Rx is not sending any rudder signal to the gyro. Why that should be, I do not know. It cannot be the Rx, however, if 3 helis show the same malfunction. It comes right back to the Tx. I don't know the Airtronics so unfortunately cannot help you there. Is it some programming?

Or were you meaning to say that you observe the blinking LED on all helis when the Tx is switched off? If so, then it might be worth switching over the Rx with another heli. It may also be a faulty/loose gyro cable/connector (to the rudder channel).

[jonp]

Originally Posted by ollie2893

Yes, I did remember the LED incorrectly. Here's the relevant portion from my manual:

Rapid flash
Displayed while data is being initialized at power ON.

Steady light
Indicates that the gyro is operating in the AVCS mode.

Off
Indicates that the power is OFF, or the gyro is operating in the normal gyro mode.

Slow flash
Displayed when there are no rudder operation signal being input from the transmitter. At this time, the rudder servo does not operate.

Intermittent flash
Alarm display when the power was turned on in the normal gyro mode. For the rudder neutral signal to be read correctly, set the transmitter to the AVCS mode and turn on the gyro power again.

Double flash
Displayed when the rudder signal from the transmitter in the AVCS mode is different from the neutral signal memorized in the gyro. Also flashes when the rudder stick was operated.

Single flash
Displayed only when the transmitter sensitivity switch is rapidly switched between the normal and AVCS positions at least 3 times, then returned to the AVCS position and
the transmitter rudder stick was rapidly moved to the left and right at least 3 times. After this display goes off, the rudder is in the neutral position.

jt41time: switch one out from another hel and see if it doing it....
jonp: I checked all three of my helis last night and they all do it!!!!

The common denominator between all these three gyros is the Tx. If your LED flashes slowly, then, according to the manual, the Rx is not sending any rudder signal to the gyro. Why that should be, I do not know. It cannot be the Rx, however, if 3 helis show the same malfunction. It comes right back to the Tx. I don't know the Airtronics so unfortunately cannot help you there. Is it some programming?

Or were you meaning to say that you observe the blinking LED on all helis when the Tx is switched off? If so, then it might be worth switching over the Rx with another heli. It may also be a faulty/loose gyro cable/connector (to the rudder channel).

Thanks for all your typing Ollie!

My solid LED turns into the double flash after about two minutes

All three of my helis are doing it.

They do it without even taking to the air.

They do it without even moving the sticks.

I have a spare, unused TX that I tried yesterday and it stll does it.

So, to recap, the sympton is that after turning everything on correctly (in HH mode), the gyro initialises correctly and the LED on the gyro is solid. After about two minutes it starts the double flashing. The LED can be made solid again by flicking between HH and rate mode 3 times as per the Futaba manual. When the LED starts flashing the heli will drift, in fact my 600 will start a mild tail wag. But there is no need to even lift the heli off - the gyro starts to double flash after two minutes while still on the ground - it even does it without any stick input at all.

I had an email reply yesterday from Airtonics saying that they know about this but they don't know what the cause is, I qoute "I too have noticed that exact same problem with my GY401's. The weird thing is that I have noticed it with every radio I use (RD8000, RDS8000, SD-10G, Eclipse7 and 7CHP) so I am really not sure exactly what is causing that. I have gone through and verified that all my flight modes have zero rudder trim, no rudder mixing, etc. to no avail. Every other gyro I have tried (Futaba GY520, EF Micro HH, and a few no names) work flawlessly and do not appear to drift. I honestly do not know if the issue is with the radios or the circuitry in the gyro, but even with it seeming to drift one or two clicks in flight I never noticed the tail drifting so I just ignored it."

So, do I need to get a new radio?

[jonp]

Originally Posted by jt41time

If that gyro blinks, then its getting a movement from your tx. or thinkning it is. switch one out from another hel and see if it doing it.... Eliminate it. If the other one does it, then its a tx/rx problem sending in ifo to it to move. If your using the same tx on all your helis with the gyro, then mabe its the gyro or the rx. switch out everything.

Thanks for all your replies......

I understand your logic and reasoning but all three helis are doing it.

[Skint Eastwood]

on the bench only try running your tail on the aileron channel on your rx, ie have the tail on the right side mode 2.

If it stops then your tx is giving some sort of extra signal on the rudder channel or it is faulty