Keep losing the 3G control over the tail

[see_e_oh]

I'm a heli newbie, so it's probably, me; but I can use some help.

I keep loosing control of the rudder gyro on my 550E. And I'm stumped ... and frustrated. Sorry for the lengthy post, but I wanted to provide enough information to be useful.

I had about 8 flights - (I've had 10 hours of flight training on an 880mm Mongoose gas heli). I'm just learning to hover this electric and experienced a small amount of "tail" wag, but otherwise showed solid gyro/rudder and other flight controls. I'm running the heli stock with a JR 9303 transmitter using the Gyro Sens (Aux2) with Gyro gain set at 62. I upgraded to v2.1 and ran through the 3G set up again. No noticeable change in wag and no change in gyro gain indicated. I had a hard time pulling out the 3G cable from the sensor and control units, and pulled the yellow lead out at one end. I've repaired many servo connectors, so this was no problem, but I bought a replacement set of cables anyway. [Subsequently I learned the trick of pushing down against the connector to release it from the white clip and then easily pull out.]

I had an expert flyer test fly the heli after the upgrade and all was well (same little tail wag). On my first flight, I drifted left a bit on lift off and ran the tail through some small weeds near the landing pad which chewed up the tail rotor blades and about 5 teeth on the forward gear. I replaced tail rotor blades, forward gear and the repaired 3G connector cable. Before putting it up myself, I brought my 550E to an expert flyer/heli mechanic at my LHS. He verified the 3G operating. As soon as it broke ground, the tail went into an uncontrollable pirouette. We rechecked all the mechanics, including pulling the main shaft and making certain the one-way clutch was working properly. Re initialized the 3G system .... test flew again .... same problem.

Took it to another buddy, actually the guy who built the kit for me, who is also an expert flyer and mechanic and verified all the mechanics were correct. Confirmed the 3G was working properly. Same pirouette problem when he lifted off. Then we removed the NEW 3G cable and replaced it with the OLD repaired cable and PROBLEM SOLVED. Rudder held nicely. We ran the GUI, and as suggested in a number of places to fix the tail wag problem, reduced the "rudder lock gain" to 50 from 70. Flew again, increased the Gyro gain to 70, Gyro held nicely, although it did a bit of hunting at the stop point/rudder change of direction.

OK, so then today, first chance to fly after the 3G cable fix, I confirmed the 3G settings were all working, then I took it out. First flight no problem other than the end of travel rudder hunting referred to earlier. Turned the AIL gain to 11 o'clock. Took another flight and didn't notice much difference, but the tail wag bothered me, so I loaded up the GUI, turned up the rudder lock gain up to 60 (from 50 but still down from the default 70). Left the Gyro gain on the transmitter at 70. At worse I expected there would be some rapid tail wag if gain too high. AIL control setting still at 11 o'clock on the 3G control unit. Lifted off and as soon as it broke ground, the tail went into an uncontrollable pirouette, had a tail strike and tipped over.

Replaced the main blades, tail rotor blades and front gear again. Loaded up the GUI, returned the Rudder Lock Hold back to the 70 default, and returned the AIL control unit setting to 12 o'clock and returned the Gyro gain to 62 (everything exactly where it was during the initial successful flights). Let my expert builder/flyer buddy confirm that the AIL/PITCH/ELE/RUDDER 3G were all working properly. He took it up slowly and, sure enough, uncontrollable pirouette problem still. He brought it down safely. Checked the 3G control over the rudder with the power on and it didn't move... tail lost again. (the tail rotor blade pitch responded to stick control, but not the 3G).

So, I've concluded this is not a mechanical or really a 3G cable problem, but rather some problem with the 3G Sensor or Control units.

BTW, I have read the threads in the Align FBL forum about the connector problem. I have verified that the white holding clip is fully engaged in the housing on both the sensor and control units, that all pins have sufficient space to plug into the female connector on the 3G cable. It appears that all pins are making contact.

Again, I'm a Heli newbie (although seasoned IMAC flyer), so this is all new territory for me.

I'll certainly call Align on Monday, but in the meantime I've ordered a replacement FL760 from Taiwan.

Anyone got any ideas?

Thanks in advance!

[markleyland]

I've got an idea. Use a separate gyro a good digital servo. I'm using the Spartan Quark with Futab BLS 251 and the tail is solid, no vibes, perfect!

P.s uncontrollable pirouette sounds like you need to reverse the gyro on the 3G. Also make sure that when you set the limits on the slider that you don't go all the way to the tail case as the control arms will buckle inwards and wont be able to return to centre.

[beans07]

Have you tried to up the gain until it wags a lot to see that your aux2 gain adjustment is actually working?

[markleyland]

Just another thought, make sure you haven't set the F.mode for rate (If your TR is anything like the DX7) and the Gryo Sense is set to Auto.

[see_e_oh]

Originally Posted by markleyland

I've got an idea. Use a separate gyro a good digital servo. I'm using the Spartan Quark with Futab BLS 251 and the tail is solid, no vibes, perfect!

P.s uncontrollable pirouette sounds like you need to reverse the gyro on the 3G. Also make sure that when you set the limits on the slider that you don't go all the way to the tail case as the control arms will buckle inwards and wont be able to return to centre.

Markelyland:

Thanks for the ideas. Gyro is set correctly. Gyro Sens is auto. The problem is that it flew fine for two flights, then when bad on the 3rd flight yesterday after the GUI change. Apart from a minor change to the rudder lock gain, the only thing I did was unplug the 3G cable from the sensor and control units to link up the 3G. Maybe its a problem with the connectors?

I'll definitely recheck the slider travel limits. Hadn't thought about a potential lockout.

I was thinking of upgrading the rudder servo. Can you explain how to add a non 3G align gyro to the 550? Does it replace the 3G control unit? This sounds very interesting.

Thanks very much.

[see_e_oh]

Originally Posted by beans07

Have you tried to up the gain until it wags a lot to see that your aux2 gain adjustment is actually working?

Yes, the Aux2 seems to be working. We needed to increase the gyro gain from 62 to 70 when the rudder control lock was moved to 50 from 70. The gain changes were slowly made and flight tested by a more experienced pilot.

Thanks for the idea.

[markleyland]

To use a separate gyro you just set up like a flybar heli, just tie up the rudder wires on the 3G and forget about them. There have been issues with the connectors.

Read this https://www.helifreak.com/showthread.php?t=194711

[see_e_oh]

Thanks much Markleyland. I really do now think that it's the connectors. I remember how much force I used to remove them the first time, and remember pulling out the connect on the sensor unit with the white clip still attached. I bet that weakened a solder joint inside the sensor unit that shows up intermittently when I've removed and plugged the 3G cable back before and after a USB GUI update.

I'll mount the new FL760 when I receive it this week and post results.

I'll also look into the separate GYRO idea too.

[beans07]

Originally Posted by markleyland

To use a separate gyro you just set up like a flybar heli, just tie up the rudder wires on the 3G and forget about them. There have been issues with the connectors.

Read this https://www.helifreak.com/showthread.php?t=194711

If your going to do this just buy a mini vbar.

Otherwise if you want to sort it out go to your local field and get the people there to help. There may not be a long wrong with it apart from some setup issues. Post up your setup file as a txt and maybe people can diagnose it.

[Vinger]

By using a seperate tail gyro you loose the piro optimization and compensation. These are one of the excellent features of FBL systems. I am sure your problem has to do with the cables, either the one from the sensor to the unit OR/AND the cables between TX and adjusting unit AND/OR the tail servo plug. This is indicated by you loosing the rudder only after fiddling with the GAI, which means you had to plug/unplug a few of them. Check all of them.

You mention that your GYRO setting in the TX are on AUTO, that surely means it is following your flight mode switch, make sure you have the same gain settings in ALL flight modes by looking at the values while switching between flight modes in the gyro menu. It could be that you are getting rate mode in one of them, which will give indications like you mentioned that the rudder servo is following the stick input but not the gyro input.

[philipfrank]

look carefully at the end of your cable connectors and see if you see a couple of the female connectors damaged.

the connectors will come out very easily if you twist while pulling them out.

[markleyland]

Originally Posted by Vinger

By using a seperate tail gyro you loose the piro optimization and compensation. These are one of the excellent features of FBL systems. input.

If you buy a quark and the USB flash link cable you will also get these options to adjust on your PC, a bit like the 3G USB kit. I doubt very much that any gyro Align comes out with can stand up next to a Spartan, my tail is solid, what more can you ask for?

[beans07]

Originally Posted by markleyland

If you buy a quark and the USB flash link cable you will also get these options to adjust on your PC, a bit like the 3G USB kit. I doubt very much that any gyro Align comes out with can stand up next to a Spartan, my tail is solid, what more can you ask for?

The piro optimization and compensation are only offered in 3 axis FBL gyros as it mixing between the cyclic and rudder. Can you sit your heli in a hover and piro flat slowly for 20sec without correcting any inputs? On my vbar units I can sit in a hover and piro on the spot for 20-30sec without and other stick command except rudder and my heli piros dead flat and does not move.

I haven't tried this on my 3G cable yet as I am still waiting for a 3G cable.

[markleyland]

I see what you mean now and the honest answer is I don't know as I haven't tried yet but surely the cylic should take care of that?

[beans07]

I don't know what it is capable or how its works yet (3G) as mine is ready for a test flight as I wanted to get the cable first and thinking about upgrading to a ICE100 aswell.

I have 3 tail servos to try and many different mounting materials to get the tail right. If I can't I will put the vbar on instead as it is rock solid on all my other heli's.

I would however be fairly sure to get the best out of the 3G for flight characteristics you need the tail component in the gyro to be running as well. Maybe it is worth trying it to get it right. I have found that any sort of vibration it upsets the gyro.

[see_e_oh]

Replaced the FL760 with a new unit. Pirouette problem fixed. Original unit back to Align for repair.

Still having trouble getting the tail wag out.

Replaced the DS620 with a JR8900G super-fast tail servo and KDE aluminum rudder tray. Will test fly during the week.

On another point, as a beginning heli pilot I don't like the torque tube. I've had a couple of tail blade strikes and besides chewing up the blades, it strips the front gear drive. Good news is I'm getting to be an expert at tearing off the tail and replacing the components.

I'm thinking of converting it to belt-drive, maybe using 600 boom and components.

[markleyland]

More sim time mate, less replacing torque tube

[beans07]

Belt or TT is a pros and cons argument. Belt casues static which can crash heli's. A bit of a hard touch doesn't crash heli's. Perhaps you could use a 600 tail fin and it might be a little longer for a bit more clearence. (I don't really know the lengths but I assume it would be).

I am a seasoned campaigner to FBL and having Vbar since V3 days I know how hard heli's and tails especially can be to tune.

I got mine to stop wagging with the 620 by trying a few different gyro tapes and adjusting some software parameters and gains in the radio. I only have a small tail kick on hard collective tic tocs, but it is absolutely solid in the hover. Haven't had a chance to dial out the kick on hard collective changes yet.

I don't think the tail servo is ideal but I think getting the vibes out od the heli and using the right tape is more the issue of the tail.

[see_e_oh]

Right on Marklyland. Just frustrated. I'll keep plugging away.

[see_e_oh]

Beans07 - what software parameters helped most?