Gyro gain question

[kenkadish]

So today I took my 500e out for its first real spin up...not really a maiden flight, but just a shakedown run, so to speak. I am fortunate that I belong to an indoor flying club which has the use of a large gym three times a week, I got here early because I didn't want people around. I am well aware of the potential danger of flying a 500 indoors, especially a first spin up.

I have all stock 500e super combo parts, and have the gp780 mounted between the screws on a lexan shelf with the receiver hanging from the bottom of the shelf. I have the gyro secured with one piece of align gyro tape.

I spooled up slowly, and was pleased with the lack of vibration. At about 1/2 stick, while still on the gym floor, and in HH mode, I started getting rapid tail twitches, maybe 2-3 inches in each direction.

I had also experienced this when I did a test spin up at home sans main or tail blades. There is a thread about this here https://www.helifreak.com/showthread.php?t=381941

I had the gain set at 65 (DX6i).

I switched to rate mode, where I have a gain setting of 45, and although I did get a yaw to the left, there was no tail twitching. I was able to trim out the yaw, and it actually lifted off in a rather controlled and soft float...I landed immediately, elated that I had actually left the gym floor by about 6" and returned without mishap.

I was afraid to spin it up further, so flew my 450 Sport and Blade SR a few times and came home. Adjusted the tail control rod to hopefully eliminate the yaw in rate mode, and then removed both the main and tail blades and spun it up again.

What I found was that at a gain setting of anything more than 52, I would get servo twitch which increases as I raise the gain.

So today's annoying question from me is why do I have to go so low on the my gain in order to eliminate the twitch?

In my experience, a gain setting of 60-70 usually works just fine.

Anyone have any idea why my gain numbers need to be so low? Is this some sort of mechanical issue? Could it be a gyro setup issue, and if so, where did I screw up? I find it hard to believe that I will have very much tail holding authority with my gain set just 2 points over rate mode.

Too cold to try outside, and I don't really feature a 20 mile drive each way to the gym just to discover that there is something simple I have failed to address.

Gyro delay is set for large helicopters per the manual.

Really appreciate any help/insights, and you KNOW, sooner or later, all these annoying questions will stop, right? LOL

Ken

[DKS_ONE]

Hey Ken, you've fallen into the GP780 abyss!!! So many here have issues with this gyro, I however do not. I don't know how you have it mounted, but sounds like the location isn't too bad. First thing I would try is setting it to small heli instead of large. That's how I have mine and haven't had an issue with the tail twitching at all, solid as can be. I also have it mounted on the bottom plate below the Rx tray, but I dunno if that has anything to do with it as it sounds like you have a good location. I also have one piece of foam tape, metal plate, gel tape and then the gyro. Dunno if this helps, but try one thing at a time, first the heli size.

[Razing0469]

I'm chasing a slight tail wag on my new 500E Pro. I initially had the gain set to 71 on the Dx6i and got a pretty steady inch to two inch wag left to right on my tail. I reduced the gain to 65% and this calmed it down significantly but it is still there and seemingly increases as I throttle up and load increses. I havent been out for a second test hover yet, but I've added a second piece of Align 3GX gyro tape on top of the single that I had. I'm hoping if the Gyro is picking up any vibes that that helps some. You'll find all sorts of ideas for padding gyros out there. You may want to add more cushion than just the one piece of tape. I'm hoping it helps mine. Also be sure your at least at 80% throttle at midstick. To low a headspeed can cause a wag. I'm not sure what your ESC is set to but I've heard that high timing can cause vibes/wag in some cases. Mine is set to mid on a stock align ESC. I plan to check my tracking to make sure there are no vibes coming from there but other than that I'm at a loss and open to ideas as well.

[kenkadish]

Razing...

WTF is it with these gp780 gyros? Have one on my 450 Sport which is just OK...clearly not the "rock solid" people comment about. As I said, at anything above 52% gain, on my 500, I get a shake...something else is cookin' here. What do you mean by "high timing"? Where do I set that?

Always curious Kenny

[Razing0469]

The timing option is set within the ESC. There are six options you can set on the Align BL70G ESC. Mine was at mid timing by default. Chances are if we have the same ESC yours is also at mid which is ok.

Sometimes I think I just wanna go get a Spartan Quark or Futaba GY520. I just might yet...lol

[ddj74]

i have my gain set at 58% with very minimal twitch or drift. this is how i have my gyro mounted. 3 layers on 3m on bottom, stainless washer and then 2 layers of 3m tape. I think a happy number is around 55% to 60%...

[Wildcards]

Originally Posted by Razing0469

The timing option is set within the ESC. There are six options you can set on the Align BL70G ESC. Mine was at mid timing by default. Chances are if we have the same ESC yours is also at mid which is ok.

Sometimes I think I just wanna go get a Spartan Quark or Futaba GY520. I just might yet...lol

I have found on more than one occasion my Align 70amp ESC has set itself to high timing after resetting it to mid!

[kenkadish]

My esc is set for mid timing, as far as I know. Beeps are 1-2-1-2-1. Today, my plan, in order, is to 1) change gyro from large to small heli, 2) go through gyro setup again, and 3) install my used Quark on the boom block and get it set up to see if, on the bench, I can get the twitching to disappear at what I consider a "normal" gain setting.

Results to follow...

Ken

[wanderer56]

I wouldn't mount the gyro on the boom block on the 500. More people have trouble with it there than not. rx tray or bottom tray will have less vibes.

[flerpie]

Originally Posted by kenkadish

My esc is set for mid timing, as far as I know. Beeps are 1-2-1-2-1. Today, my plan, in order, is to 1) change gyro from large to small heli, 2) go through gyro setup again, and 3) install my used Quark on the boom block and get it set up to see if, on the bench, I can get the twitching to disappear at what I consider a "normal" gain setting.

Results to follow...

Ken

Yes. Troubleshooting by substitution of known good.
Good move. Induce a change, observe the results then
make a decision based on the results.

If the results are substantially the same with a different gyro
then I'd substitute a diff servo.

[1sickvibe50]

how is your gyro mounted in your heli? it should have foam tape with a metal plate as someone mentioned before. also did you setup the servo endpoints? maybe the gyro is over stressing the tail servo which is easily adjustable from the gyro

[kenkadish]

Well, I think I may have solved my problem! I had purchased a barely used Quark about a month ago, and installed it in the 500e today. Spooled it up without main or tail blades, and there was not a bit of the twitching I had seen with the GP780

Will try to try it out tomorrow again at the gym, or outside if it's warm enough.

The GP780 is for sale and I'm looking for another for my 450 Sport.

Ken

[Razing0469]

Nice! Like I said earlier Ken I think I'm headed for a Quark or a GY520. Glad it worked for you.

[nbells]

Ken.

Forgive me if I am stating the obvious here but ... since its a new kit, why not take the Gyro back to the place you bought the kit from or give your Align dealer a shout, you might get a replacement ? or at least a deal on another decent Gyro ?

I have no experience with the 780 as my kit came with the GP900 and I am running a gain of about 64% and my tail is rock solid ...... infact every so often I move the rudder myself just to make sure its still going to react when I need it to .... I guess thats an old SR habit there ........ always having to use the rudder !

Nigel

[nbells]

Ken.

Forgive me if I am stating the obvious here but ... since its a new kit, why not take the Gyro back to the place you bought the kit from or give your Align dealer a shout, you might get a replacement ? or at least a deal on another decent Gyro ?

I have no experience with the 780 as my kit came with the GP900 and I am running a gain of about 64% and my tail is rock solid ...... infact every so often I move the rudder myself just to make sure its still going to react when I need it to .... I guess thats an old SR habit there ........ always having to use the rudder !

Nigel

[nbells]

da*m .... now why did it post twice ??? Appologies