ElectricDurango

I have a trex all stock except for carbon boom. Im using a optic 6 for radio. Whatever i do i cant seem to get the heli trimmed it always want to go to the sides or front back. it always wants to twist like the gyro is messed up also.

is there a trim out step by step proccess? This is my first heli. i know i started with a more compex one.

with my gyro i had to turn the gain all the way up for it to even slow down the spinning. Then i tried to do additional gain on the radio as well.

HELP ME I DONT KNOW WHAT IM DOING


Trex 450
optic 6
electron 6
3103 on alerion, align standard on elev and pitch, HS-50 on rudder,
400dh motor
zoom super head loc and standard gyro
tp2100 3s
cc 25 amp esc

UKgroucho

You need to get a few things sorted out. I'll describe a few things here but you should also visit www.trextuning.com - there is a very good setup guide there which includes great advice on WHICH holes in the servo arms to use (amongst other things)... Trex is very sensitive to Aileron and Elevator movement so you should use the inner holes.

First the left/right & forewards backward stuff (Aileron and Elevator).. The swash plate should be level before anything else - so, when you power up, the swash should be level. You can trim a certain amount on the Tx but if you have to trim a LOT then check that your linkages are the right length (offer them up to the templates on page 5 of the Trex manual). If the lengths are right then you may need to adjust the servo arms.
- Power up and set all trims to the middle, power down.
- If the swash is not level then remove the servo arm from the relevant servo and try to select a different mounting point that makes it as level as possible. You cannot completely level the swash this way but you should get it close enough to do final adjustment with subtrim (if your Tx has it) and trim. You need to do this for the Aileron (left / right) and Elevator (forewards/backwards) servos.
- For the Pitch servo, when your Tx has a 0 pitch setting (50% on my Futaba... not sure about your Tx) then the pitch slider should be in the MIDDLE (see trextuning) AND the blades should be at 0 pitch. If you do not have a pitch gauge then eyeball it.. it will be close enough providing you have all the linkages exactly as per the manual. A pitch gauge is really helpful as you should also set full pitch (move the servo / slide up with no power and check / adjust linkages) and negative pitch (slide down) to make sure that both blades move the same. You adjust the lengths of the top linkages (SF levers to flybar) for BIG changes and the bottom linkages (swash to SF mixer lever) for fine tuning. To adjust, disconnect the linkage and screw / unscrew one ball connector a FULL turn - so the little A stays on the 'outside' of the ball when you connect. Pitch auge (form Align) is cheap and the very act of using it helps you understand how all the 'bits' in the head relate to each other and move together - I highly recommend getting one but you can make the Trex fly quite well without using a pitch gauge (I did).

I cannot really help too much with the gyro other than to offer the following advice.
- Make SURE that the pitch slider on the rear shaft can move freely. Disconnect from the pitch servo and try pushing / pulling the pitch control lever from the 'servos perspective'. .. using the pitch control rod. If the rod bends much when you do this then you have binding in the tail. I messed up with this on a rebuilt by screwing one of the tail blade holders in too tight (the little allen / hex bolts.. part 138 HT6001) and the tail was terrible.
- Make sure that the tail rotor has full movement in and out on the shaft when controlled by the servo - you generally need to do this with the gyro in RATE mode (not HH). I ended up moving the servo mounts a little to make this possible once I'd tried to adjust the 'throw' (how far the gyro allows the tail pitch to move) on the gyro - I was getting full movement one way but not the other and could not adjust by re-setting the position of the arm on the servo - so I 'slid' the servo along the boom a couple of mm.
- THIS MAY NOT APPLY TO YOUR GYRO! For a Gy401, you need to set up the tail so that you can sustain a hover in RATE mode and then switch to HH... the gyro remembers the setting.

You do have your gyro (and tail pitch servo) set the RIGHT way, not reversed.... if the heli really spins as soon as you throttle up (and all of the above is done) then this is likely! If there is a reverse switch on the gyro then try that, OR switch the channel direction in the Tx.. do ONE at a time, not both together (althoughyou may need to do both to make it work).

Oh... and make sure all the ball connectors etc. are reasonably tight... minimise play (slop) in the head.

Keep at it...the Trex is a blast
I'm not sure that I would have started with a Trex as you tend to break SF mixers / blades etc. but it is definitely easier to fly than a small FP... and parts are cheap enough. If you have not done so then order some spares... One outdoor spares kit, one or more seesaw kits (the SF mixer levers are the bit you need, you get a pair in the outdoor kit but the seesaw is also a possible breakage), washout assembly, steel main shafts (come in pairs, incredibly cheap.. although I just ordered a titanium one from Like90), extra blades, a pair of tail blades, tail boom. I guarantee that you will break these bits but they really are quite low cost (although the bill for all the stuff I outlined will be quite a bit). If you do not 'stock up' then you will be grounded by breaking a small plastic linkage... you can try CA but having spares to hand is 'reassuring' so you push things and learn more.

tanasit

UKgroucho pretty much cover all you need to know: Make sure the ball lnks are not too tight, see tips on how to fix that at Trex Tuning.

ElectricDurango

Visualize this. You have your heli powered up somewhat and you can picture the circular shape displayed by your main blades. When you roll to left or right is the circular shape shift to the left and right perfectly or does it tend to pitch forawd or back a little also? The same happens for forward circular shape movement.....tends to have a little left and right also. I was playing with the flybar and it seemd to go away but it just returns afer a few mins.

UKgroucho

It should pretty much do what you want BUT the Trex is VERY VERY sensitive to head movement inputs - that's why you use the innermost servo arm holes and (if your Tx can do it) decrease sensitivity using -ve Expo on channels 1 and 2.
My guess is that even when you think you're just doing side to side or fore / aft you are introducing a little movement in the other plane.

Calm things down a bit by remounting servo holes and applying some expo.

warren52nz

That was interesting reading UKGroucho. Although I have A Century Elite 3D Pro, I have a GY401 gyro which you mentioned. I'm confused by the Gyro settings on my Optic 6 Tx. If I set the "Gyro" setting to 50%, the tail blades stop responding to the rudder control completely. But if I set it above or below 50% it starts responding again. The Optic 6 manual doesn't explain this.

And, if I set my "End Point Adjustment" on Channel 4 (rudder) to limit the amount of movement of the rear blades, it will move a bit quickly but then will slowly move to FULL servo rotation one way or the other.

I'm guessing the fast movement is from my input and the slow movement is coming from my gyro which is trying to twist the model but is getting no result (because the motor is off). So it tries harder andharder until it runs out of travel on the servo. ???

Does anyone understand these symptoms? I'm not sure what to set to what and, as we all know, experimenting in the air can be EXPENSIVE!

I probably should have started a new thread, sorry.

Thanks

tanasit

I too had trouble setting the GY401 on my Trex and finally understood the process as below:

Set ATV on rudder to 100%. Turn on the sytem with HH on (confirmed by the steady red LED on the 401), adjust the limit pot while moving the rudder stick to both extreme until the servo won't bind. If it binds on one side but not the other then remove the servo arm and reposition toward the side that doesn't bind. You may not get perfect setting here but you want more "right" rudder than left if it has to be. Switch to normal mode and lift off to set the gyro sensitivity and then set the rudder trim, then set the same trim position for all the other modes (HH, idle up 1, 2). If your servo is NOT a digital one, make sure to set the switch on the 401 to OFF. If you want faster piro rate, then increase the rudder ATV to more than 100%. Keep the delay to minimum unless you want to soften the rudder response.

The GY401 requires 51% and up for HH mode but the percentage arrangement in different brand TX cause confusion, so I only look at the steady red LED to confirm the HH mode. then increase the sensitivity until the tail started to wag, then back it down. Make sure to set this at higest possible head speed that you plan to fly.

wldcwbypilot

If your still having problems decrease your end point adjustments, easier than doing it mechanically. Thats what its there for, don't mess with the subtrim adjustments. I have mine setup withe the servos at about midway in. I then did end points at about 40 percent on channel 6, 1 and 2. cut the servo travel down for inital flight testing. Also make sure your gyro is mounted correctly, most manufactures diagrams are 180 degrees off. I have built more than a few helis and each time i follow the manufacturers diagrams on the gyro placement its wacked and have to turn it. I did have to turn up the gain slightly, my trex is rock solid. cheers happy flying!!!!!!!

ElectricDurango

Thanks everyone for your help and time consuming posts.

The Heli should balence dead even when hanging from rotor blades correct? <-- I mean no leaning forward or backwards correct.

tanasit

Hold it by both end of the flybar rod positioning perpendicular to the boom! Slightly leaning forward is okay.