3GX Did You Know...!!!

[tourerjim]

Ian, the subject of sub trim has been mentioned on other forums HF for one that no sub trim must be used but the problem is using transmitter trims with 3GX on my heli's does not work well its hard to explain why but its abit like links tightening the more you put in.
The only way I can find around at the moment is to use sub trim so its stored in 3GX dir mode, I even tried to adjust the links at first but found she drifts to much one way or other but I think I may have an idea of the fault so i'll just go & test it now & post back in a bit

I've just come in from giving the heli few flights with the other idea I had in mind & I think there is a fault with the 3GX as I think its to do with not correctly returning swash plate to then levelled position.
What I done was to put small amount of weight to the front of my 450 just enough to off set cog away from tail & then hovered for about a minute or so when heli started to drift forwards so landed & removed weight to tried again & heli drifted backwards, again put the weight back on & heli started drifting forward so then I upped the gain pots full on" then hovered to find it took heli much longer to drift so turn pots down to 11 & found drift was real bad constantly having to control drift.
With fresh battery I then turn gain pots full on & hovered with little to no stick input & heli was so very stable & after 4 mins hover no noticeable drift & then done another fresh pack & this time with gains back down to 11 she was drifting all over the shop but tail-ward being the worse so after a minute had to land so upped the pots full on but because heli is so locked-in I found it difficult to do most simplest things like doing circuits.
So could it be 3GX is not finding the swash levelled position if gains are to low.? if I turn my gains up anymore than the 1 o'clock I start to lose some of my 3D manoeuvres.

[GIXERMAN]

For some weeks now I've been trying to cure the tail drift on my 450pro v2 but to no avail & was surprised to read the amount of posts with same problem & with different size heli's with 3GX.

Ian (coolice) might help on this one.

We all know you have to setup 3GX in DIR mode & zero stick then level swash plate but to do this you need to dial in some sub trim on one or more servo's to get the 90 degree, for instants on my 450 aile servo dialled in 36% & elev 18% with swash levelling tool, so the setup is fine you would agree" now here's the weird bit when you first fly her there's no drift at all until about 25% of battery used then she's starts to tail drift, so I took a peace of (coolice) advise on a previous post that is to dial in a bit of sub trim on aile servo to compensate so the other day I took to the field determined to sort out the problem so dialled in swash mix then flew heli, alls fine but after a bit heli started its drifting so dialled in a bit more swash mix & tried again then again & again till I got to 80% still with drift 'weird' so back to the bench & zero all sub trims & suddenly the swash went completely crippled.? with servo horns all over the shop quickly disconnected battery & sat down to get some thoughts together.

This is the interesting bit because I forgot that I zeroed the sub trim & went out to fly it again & after couple mins flying I noticed I had no drift so continued to finish the flight but no drift.?
Got the tools out took the head of whilst battery still connected fitted levelling tool to find swash plate level so put in DIR mode to find swash not level so took it out of DIR to find swash level so does the 3GX level the servo's itself...?
Anyhow I have just done same with my 500efl again I've got sub trim dialled in when in DIR so zeroed sub trim & our of DIR swash is level all servo's 90 degrees so how does 3GX know where 90 degree on servo is...?
Weather permitting im going to fly the 500 like it tomorrow.

Are you running 3GX on 2 no satelites or a reciever 6/7 channel?

[tourerjim]

2 sats but reading different forums it doesn't seem to make any difference if its sats or rx

[GIXERMAN]

if using sats this will be rules out .
I set up 2 models for other people , 1) problem 450 using a dx6i and 6200rx, went threw all set all good. just before 1st flight switched model on 3gx went threw its startup and swash tilted forward then went up and down twice. this was because 3gx was starting quicker than rx. so rebound and was ok
2) 600esp DX8 and AR7000, went threw all set same again. before first flight swash tilted forward and then went up and down twice, so i took rx and replaced with 2 no sats resetup and was perfect.

[tourerjim]

if using sats this will be rules out .
I set up 2 models for other people , 1) problem 450 using a dx6i and 6200rx, went threw all set all good. just before 1st flight switched model on 3gx went threw its startup and swash tilted forward then went up and down twice. this was because 3gx was starting quicker than rx. so rebound and was ok
2) 600esp DX8 and AR7000, went threw all set same again. before first flight swash tilted forward and then went up and down twice, so i took rx and replaced with 2 no sats resetup and was perfect.

So you saying you now got no drift.?

[GIXERMAN]

yeh no Drift on either, also my friend has a 600N which he is very happy with

[helimadness]

I was going to try blue tack in the nose of the 500 to correct COG but its really very close with the battery forward.

Bit off topic but I extended my boom on my mini CP by 20mm but using 2 old booms and gluing together with about a inch of overlap just behind where it pushes into the frame. Would have added some weight and moved everything back so COG should be much further aft. Hovered in the lounge this morning and thing is solid as. I know its a totally different animal but the FBL controller in that can obviously handle COG problems.

Cheers

[AlastairC]

OK run two batteries through my 450 last night to try to sort this drift. Before these flights:
1) Put the DFC head on
2) Replaced tail bearings
3) Replaced main shaft bearings
4) Minimised sub trim <20 on my DX8
I am running v2.0 with two sats setup. Pots at 1 o'clock. Default settings apart from flip and roll upped a tiny bit to 55
The first minute of my flights were great and then the backwards drift got progressively worse.
My COG is good and can piro on the spot (at the beginning of the flight with no problems).
I am also running a CC ICE 50 with the governor set and the logs look very good at giving a constant head speed (so can rule that out as battery drains). Also according to my telemetry on the DX8 the RX voltage was min 5.8 and max 6.

Not sure if this helps others here but just cannot see how it is setup as the first minute or so is great.

[muscleflex]

sorry but what the heck is DIR mode?

[AlastairC]

sorry but what the heck is DIR mode?

The first part of the setup when it bypasses the gyros and you set the pitch/collective limits/servo's at 90 degrees.

[Made2Fade]

Out of interest what version of firmware are you guys running? Which is the best? If its anything like the 3G then the latest version was terrible on the cyclics. Have you been getting this drift with all versions of the firmware??? Maybe also something to look at.

[bikerflier]

Had the same problem on my 500 with v1.2 and v2. With Align head and noe DFC head.
Just about to put DFC on 450 with 3GX. Was fine with 3G, standard head and RJX head. Hope I don't get the same problem.

Out of interest what version of firmware are you guys running? Which is the best? If its anything like the 3G then the latest version was terrible on the cyclics. Have you been getting this drift with all versions of the firmware??? Maybe also something to look at.

[muscleflex]

The first part of the setup when it bypasses the gyros and you set the pitch/collective limits/servo's at 90 degrees.

ahh so you guys are just referring to the 3gx software bit?
i thought DIR was a function on the transmitter... like a dual rate something but i could not figure out what DIR stood for.

[AlastairC]

ahh so you guys are just referring to the 3gx software bit?
i thought DIR was a function on the transmitter... like a dual rate something but i could not figure out what DIR stood for.

The DIR mode (DIRect I presume) is on the 3GX itself. So you don't really need a PC to set it up (unless you mount it under the main shaft).
Where the transmitter is coming in is in the sub trim. A good mechanical setup should not need any sub trim but on a 450 this is really difficult. So have been trying to get it near zero and even removing it from the tx after DIR setup is complete (as the 3GX seems to remember the zero'ed positions). ..... at least this is how I understand it.

Anyway mine seems to fly ok for a while and then goes off.. so seems more like something heating up in the unit during flight and causing the drift. I am at the point of not flying my pro and waiting for the new Spartan FBL.

[tourerjim]

Out of interest what version of firmware are you guys running? Which is the best? If its anything like the 3G then the latest version was terrible on the cyclics. Have you been getting this drift with all versions of the firmware??? Maybe also something to look at.

I've tried my 450 on all 3 versions & its just the same in all but the advantage of v2 is the ease of parameter settings, 500 however is spot on with no drift.