CGY-750 Settings

[Nutter]

I can't do the trim flight as I'm using a JR transmitter and don't have the channels to do the flicky-switcy thing.

So, I'm going for AVCS setup on both cyclic axes and making sure I get the c/g of the heli bang on.

That's my theory anyway.

You can still do the trim flight on a JR tranny. I've done it on my mates CGY-750 and JR X11. All you have to do is after the trim flight, turn off the CGY-750 and back on again. Job done!!!

[Planehazza]

I can't do the trim flight as I'm using a JR transmitter and don't have the channels to do the flicky-switcy thing.

So, I'm going for AVCS setup on both cyclic axes and making sure I get the c/g of the heli bang on.

That's my theory anyway.

Yup do the same, fly it in norm, but instead of using trim and flicking between norm and AVCS, use the sub trim feature of the CGY750 to adjust the swash.

[Steve]

You can still do the trim flight on a JR tranny. I've done it on my mates CGY-750 and JR X11. All you have to do is after the trim flight, turn off the CGY-750 and back on again. Job done!!!

Bare with me on this, I'm new to this unit.

So if I set the fbl controller into 'normal' mode on both the aileron and elevator rather than AVCS mode, then do a trim flight and use the Tx trims to get it bang on.

Then I turn the heli off and back on again, leaving the Tx turned on???

Then I reset the aileron and elevator functions back to AVCS.

Is this right.

I need step-by-step destructions please.

Trim flight - do you just trim it in the hover or in forwards flight, or both?

Or alternatively, Harry is saying just skew the swash plate a bit using the internal servo centre settings. Mine needs a bit of right aileron.

[Nutter]

That's absolutely the correct way to do it. However you will need to turn your tranyy off once the heli is turned off for it to rebind properly? Leave the trims in the tranny once the trim flight is done and do the trim flight in hover.

[Steve]

That's absolutely the correct way to do it. However you will need to turn your tranyy off once the heli is turned off for it to rebind properly? Leave the trims in the tranny once the trim flight is done and do the trim flight in hover.

So let me get this right.

You're basically saying, once trimmed in 'normal' mode, I switch the CGY750 back to AVCS on the controller in each of the pitch and roll axes, and then just fly it with the trim settings as they are on the Tx.

Sorry to labour this point, but it just seems odd to me. The theory being that if I fly the heli in AVCS mode with say 10 points of right aileron constantly held in place by the Tx trim then the heli will surely want to very slowly right roll all the time?

Mind you, having said that, when I was flying it yesterday for the first time, I was constantly holding the right aileron over just a teeny-weeny tad to keep it it one spot and stop it drifting away, so I guess it amounts to the same thing in real life?

Old school theory says you never use trim when flying a heading hold gyro, and modern fbl controllers are no different from old tail only gyros in this respect. They just control 3 axes rather than 1. I think I need to re-jig my brain on this one.

Thanks.

[Planehazza]

So let me get this right.

You're basically saying, once trimmed in 'normal' mode, I switch the CGY750 back to AVCS on the controller in each of the pitch and roll axes, and then just fly it with the trim settings as they are on the Tx.

Sorry to labour this point, but it just seems odd to me. The theory being that if I fly the heli in AVCS mode with say 10 points of right aileron constantly held in place by the Tx trim then the heli will surely want to very slowly right roll all the time?

Mind you, having said that, when I was flying it yesterday for the first time, I was constantly holding the right aileron over just a teeny-weeny tad to keep it it one spot and stop it drifting away, so I guess it amounts to the same thing in real life?

Old school theory says you never use trim when flying a heading hold gyro, and modern fbl controllers are no different from old tail only gyros in this respect. They just control 3 axes rather than 1. I think I need to re-jig my brain on this one.

Thanks.

That's exactly what confused me mate. Surely it seems that setting 10 points of aileron trim, then telling the 750 to remember it (either by toggling between AVCS and norm 3 times, or restarting the system) and leaving the trim on the radio will input the trim twice? Apparently not though. Personally, I'd rather not use trim and just adjust it mechanically. Unless the model is off balance, a perfectly level swash shouldn't drift, but we'll see. I have mine perfectly level (using a leveller) at centre, top and bottom. I was particularly fussy with this model and I ended up only needing to use about 5uS of sub trim via the 750's swash menu on one of the three cyclic servos. I had to enter about 4% PIT-ELE mix on the expert menu to get it level at top, otherwise it was fine mechanically.

I may maiden mine today, but I don't know what's wrong with me lol. Perfect weather, haven't flown in weeks, but I just can't be bothered lol

This guy explains it a lot better than I do:

Leveling Swash
It is very important that if a prior trim flight was done using the Futaba procedure to reset the cyclic center position, that you reset your swash menu using the Swash Expert else this procedure will not work. Getting your heli to fly level. I am not a fan of the standard trim process for the CGY750...also some people have issues with their helis even after trimming it perfectly, this is a known issue and i'm sure fix will be coming but till then i came up with my own method that is working much better..if your heli doesnt have any issues with flying level, then skip this but if you have tried everything and still have poor results, this is what i found that works. IF you have already done a trim flight, where you have memorized your neutral points, then you will need to reset your Swash menu to use this method...if you do reset it, be sure to copy all your expert and basic settings down. Instead of trimming my heli using the trim controls on my TX (which i hate) i instead level my swash using a swash leveler using the Swash Basic menu's Neutral points (pg48 of manual) I level the swash using the Ail.ntrl, Elev.Ntr,& Pit.Ntrl trying to get it as good as i can. It is very important to make sure your heli is level when doing this and that your swash links are all equal to ensure best results. I also try to keep one of my servos (Pitch or Elev if possible) at zero..i pick the servo which is most dead on and instead adjust the other two servos. This isn't always possible depending on your setup but will simply your trimflight if changes need to be made. Also you want to ensure that no one adjustment is more than 90. Chances are if you are that high then moving the servo horn 1 spline up or down is needed. Once your swash is level and your blades are level, then you must perform a trimflight. Much like like the original trimflight, you will want to set a switch on your TX to be able to switch your cyclic gryo between AVCS and NORM for both Ail&ELE. Its important to do this on a calm day but Simply hover heli and switch your cylic gyro to NORM. If it holds its position then you are done but if not, you will need to go back to your swash basic menu and adjust your Ntrl points. Try in small increments of 5 points. I find it best to only make changes to 2 of the servos, so if your pitch.ntrl or Elev.ntrl was zero then keep it at zero and adjust the other servo. It usually will take 2 or 3 attemps to get it to stay. Remember in Rate/Norm mode, very little wind will make you drift and your COG will have a greater effect. Once your heli is flying level and is not drifting in calm conditions then simply land and switch your gyro back to AVCS mode. DO NOT perform the gyro center memorization procedure, simply switch it back to AVCS only.

More info: http://helifreak.com/showthread.php?t=327174

[Steve]

This amounts to just altering the length of the push rods up to the swash plate. Much quicker and easier.

So after making all the effort to get the swash plate level on the bench, all you're doing is making it un-level and trying to find the point where the helicopter finds its own neutral balancing point.

How come that doesn't surprise me?

[Planehazza]

This amounts to just altering the length of the push rods up to the swash plate. Much quicker and easier.

So after making all the effort to get the swash plate level on the bench, all you're doing is making it un-level and trying to find the point where the helicopter finds its own neutral balancing point.

How come that doesn't surprise me?

True, but surely that's also what you're doing using the trim function? I'd rather do it on the model end personally. I'm hoping (fingers crossed) that with the swash level and the CG right, the model shouldn't drift...

In any flybarred model, if it drifts and I had to use trim, I'd go back and adjust it on the model. Same thing here.

[Steve]

I think that's where a bit of myth comes in Harry.

The idea that a perfectly level swash plate will give a spot on hovering heli just doesn't add up. A helicopter as a giant gyroscope and there are all sorts of forces acting on it in flight including a sideways push from the tail rotor and gyroscopic progression in all sorts of directions. In order to make the heli hover hands off, you have to make tiny compensations in each axis to overcome these, so the swash plate will never be bang on level. It might be close, and working from level is a logical way to go through the setup process, but if you want to be purely accurate mechanically, you need to adjust away from level. And further more, these effects will be altered if you change the head speed, just to make it even harder.



Oh well, adjusting is required anyway.

[Steve]

Firstly, thanks to Squeeky Pete's advice on altering the governor expert settings to stop the over-speeding. It worked a treat and now the unit is working great in governor mode.

Now, next question after another flight today. When I roll, both stationary and in forwards flight, the heli comes out at the end of the roll in quite a tail-down attitude. I've paid particular attention to getting the c/g right on the model so that can be ruled out. If I do a stationary elevator flip, it goes over nice and straight with no unexpected aileron inputs.

Any particular expert settings I should be looking at?

[nookybear]

Probably a finger thing.
Try a load of expo on elevator only then do stationary roll to see if its improved.

Sent from my X10i using Tapatalk 2

[Nutter]

Firstly, thanks to Squeeky Pete's advice on altering the governor expert settings to stop the over-speeding. It worked a treat and now the unit is working great in governor mode.

Now, next question after another flight today. When I roll, both stationary and in forwards flight, the heli comes out at the end of the roll in quite a tail-down attitude. I've paid particular attention to getting the c/g right on the model so that can be ruled out. If I do a stationary elevator flip, it goes over nice and straight with no unexpected aileron inputs.

Any particular expert settings I should be looking at?

Steve

First of all sorry for not replying to your question about leaving the trim in your trannk after doing the trim flight. But yes as Harry says you do leave it in.

It could be your thumbs on doing the rolls as mentioned above, but if it's not you can look at elevator to aileron F/F mixing in aileron gyro expert menu, but I've never had to use it.

[Steve]

Might be something as simple as gains too low.

Done a bit more instruction book reading and it suggests aileron and elevator gains should be between 70 and 90% for 90 size machines. Currently at a first attempt value of 60% so I need to ramp those up and find the oscillating point I guess first of all.

[Nutter]

Yep. I was at 85% on elevator and 75% on aileron on my 700N's.

[airwolf]

Having set up and flown 3 other BeastX and a Tarot XYZ FBL unit I have to say that the CGY has been the easiest one to do, mainly because "off the shelf" it seems to work amazingly well. I have only had 4 flights so far but immediately it combines the control feel around the hover of a flybar with the accuracy in forward flight of FBL. This suits me well as I was always a little disappointed with the feel in the hover of the BeastX.

Are there any tips of how to spice up the roll and pitch rates for 3D type flying? I presume increasing the TX ATV on aileron & elevator is the main way? I will also try increasing the cyclic pitch.


TT X50, TT G4, TRex 500, TRex 250, Morley MXB