Noob 3GX questions

[Crumpet]

I have just updated to V4.0 after flying it on whatever it came with (no idea sorry)
It flew okay-ish before but now I'm finding if i touch the rudder it jumps about 20degrees left (anti clockwise)
Doesn't matter if I'm putting left rudder or right, when I let go it jumps 20deg (ish) left.

I have it plugged in to the 3gx software now and have found 'rudder locking gain adjustment' but how does that differ to the gain I can adjust on the transmitter? The transmitter gain definitely works and rudder locking gain adjustment doesn't change as I change it on my transmitter.

Lastly, if i have my pots at 12 o'clock it oscillates terribly. Could it be trying to over react to a vibration? Once i turned them down to 10 o'clock it was fine.

Thanks a lot for your upcoming wisdom!!

[coolice]

Hey.

The standard lock gain settings are too high, lowering this value from 70 to 50% is normally a good value.
Basically rudder lock gain is how tight a grip the gyro has on the tail rotor when there is no input from the pilot, the higher the value the tighter the grip, but sometimes if it's too high you can observe a perceived wag where the tail cannot find a centre as the lock gain is constantly adjusting the tail. This could be your problem as the tail is less likely to want to move from its current position.
This value can only be changed using the PC software and you will find lowering it will allow you to run a higher Tx gain value.

If your gains are too high the 3GX could be reacting to vibrations or it is just too high and again as you unsettle the rotor disk to perform a manouver the gyros try to stop the action and induce a visable wobble.
Try reducing the gain pots until you remove the wobble but still feel the model is held nicely in the air and feels predictable.

Hppe this helps?
Any questions just ask.
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[Crumpet]

Thanks very much coolice.

The only thing I didnt get is the difference between the software rudder lock gain and the transmitter controlled gain? Is it adjusting the same thing? You said it changes the grip on the tail but isn't that what the transmitter controlled gain is adjusting aswell?

Thanks again!!

[tourerjim]

Can make a difference knowing what heli its on, I agree with Ian on this one but ive also found by using the cyclic gain pots to setup your ground to hover behavior is best & then pc 3GX parameters to control cyclic flight behavior.

[Crumpet]

Its on a Trex 450 Pro DFC

[tourerjim]

Its on a Trex 450 Pro DFC

I can check what my tail gain is on tx for my 450 DFC tomorrow if you like.

[Crumpet]

That would be awesome.

Really appreciate the help from everyone. I'm completely lost with all the adjustable parameters on this!

[tourerjim]

I'll post my 450 parameters tomorrow night.

[coolice]

Thanks very much coolice.

The only thing I didnt get is the difference between the software rudder lock gain and the transmitter controlled gain? Is it adjusting the same thing? You said it changes the grip on the tail but isn't that what the transmitter controlled gain is adjusting aswell?

Thanks again!!

Hey Buddy.

You're very welcome, glad to help.

No, the two gains (lock and normal Tx based) are totally different. CSM used a good analogy to describe the effect of the lock gain from memory. Basically, visualise the lock gain as two big springs connected to either side of the tail rotor with a small amount of tension on them to hold the tail in one place. The lock gain increases this spring tension keeping the tail in one position when the pilot is not commanding a change in tail position through the rudder stick. The knock on effect is a better held tail during high aggressive manouvers, but of course the negative effect is that the tail can be more difficult to move when the pilot asks it to, so it's a balancing act between this lock gain and the usual transmitter gyro gain.
Many factors effect both gain values, such as tail rotor speed (faster = more thrust), tail servo specs (speed & torque) tail servo arm length etc. so you adjust to obtain the best for your model.

Experience has shown the Rudder Lock Gain found in the PC software needs to be at 45~50%, any higher cause's problems in most models. A lower lock gain then allows a slightly higher tail gyro gain value within the transmitter.

Another consideration is your tail servo control arm on the servo, with the 450's I've found the small round servo disk Align give with the tail servo works best. It puts the steel control ball about 7mm out from centre. I'm trying to remember if you then need to mount the servo from the underside of the tail servo holder to use this, but it's worth doing to get a better tail performance.
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[Crumpet]

That could explain my problem. The standard V4.0 was set to 70%

Turned it down to 50% and will be taking the laptop out with me for a setup day.

Hopefully Jim gets back and i'll have a headstart!

[coolice]

That could explain my problem. The standard V4.0 was set to 70%

Turned it down to 50% and will be taking the laptop out with me for a setup day.

Hopefully Jim gets back and i'll have a headstart!

Evening Mate.

Yeah, I think this will be a good place to start.

Here are my 450L 3GX V4/4.1 settings file, load them up into the PC software and give them a go.
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[tourerjim]

Here's mine, save to 'C' my settings then open pc software 'open tab' & you should see the file.

[Crumpet]

Great! I'll upload them today. Thank you very much! I'll report my findings

[Crumpet]

After hours playing with settings, using tourerjim's settings, re-calibrating the tail all effecting the problem 0% I installed V3.1 (which I've also never used before) instead of V4.0 and it went away from the start.

Not sure why but it obviously didn't agree with something.

Very relieved, thanks very much for all the help!!

[coolice]

Morning mate.

Ah good news, you're flying.
V3.1 is ok, never been as good as V2.1 overall and V4 is better if you forget the annoying servo twitch V4 has when not flying.

Just remembered a specific setup procedure now required with V4 to remove an over-shoot/bounce-back on the tail after quick stab tail inputs, re-reading your post could this have been your problem?
V4 needs the tail setup in rate mode, adjusting the tail pushrod to achieve a hands off hover and also reducing the tail delay value to zero. You're helped here by being connected to the pc at this point, as you flick the rudder stick in the delay direction you want (large or small heli) observe value change to 0 or a low percent and just let the 3GX reset on this parameter to save the value, as a bug prevents the value being saved if you press the rubber button to move on.

Worth remembering for other V4 users.
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