RunRyder - how much gain is too much?

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Beginners Corner > how much gain is too much?

kcass518
Veteran
Location: Manhasset, NY - USA

Checked my gain yesterday. I raised it as much as possible, then backed it down. I ended up at about 88%. I don't know what that means, but the heli flies great and I haven't moved my ball link.

06-03-2008 01:37 PM

nmrs
Senior Heliman
Location: Austin, TX

kcass I just re-measured the length from servo hub to ball center and came up with about 9.5mm again. Your tail servo mount looks different from mine though (is your's V1?). Your whole tail servo looks to be mounted closer to the tail boom. At 9.5mm everything on mine looks to be 90*.

I'm still not completely happy with my tail. Its not drifting, but seems a little mushy. I've had to bring the gain down to 42% now and it still seems to wag a little bit, so I may need to bring it down even more, which will probably just increase the mushiness.

06-03-2008 03:27 PM

kcass518
Veteran
Location: Manhasset, NY - USA

Yup, mine's a V1, but I don't think that should matter. I just reread your original post, and I'm wondering why you would have a regulator in there? I use a 3S LiPo, 2200 mah, 25C through a Jazz ESC, and I plug all my stuff right into the receiver. I don't know how many volts it's putting out, but I'm not aware of the need for a voltage regulator with this setup, and that might be one thing giving you problems. The only other thing I might suggest is that since you've tried moving the ball link farther away from center, try moving it closer and see if it improves.

06-03-2008 05:40 PM

nmrs
Senior Heliman
Location: Austin, TX

I have the regulator for the s9257 tail servo. It's not rated for 6v. Regulator is between gyro and tail servo. I may try drilling a hole in my servo arm a little closer to the center or just go back to that star I was using and see if I can get it a little closer. I think that being closer to the hub should give the tail servo (and therefore the gyro) increased resolution, though I will probably have to run a higher gain (since I am decreasing mechanical gain by moving it in).

06-03-2008 06:04 PM

kcass518
Veteran
Location: Manhasset, NY - USA

I hope somebody corrects me if I'm wrong, but according to Futaba, the GY401 is rated for 4 to 6 volts. On the Tower Hobbies site it says that if you're using a 6 volt system, the 401 needs to be regulated down to 6 volts max. Even though Futaba rates it to 6 volts, if you have a 5 cell nicad hooked up to it, it will be getting more than 6 volts most of the time. My point is, if you needed a regulator in there, it should be between the receiver and the gyro which would also hold the current to the servo to a lower voltage. But the BEC in my Jazz puts out 5 volts, and I would suspect that your esc does the same which would make a regulator in there redundant, unnecessary and possibly problematic. If I understand your problem, and if it were me, I'd remove the regulator. If that didn't solve it, I'd shorten the servo horn per the GY401 manual. Under "One point advice", it states that "when hunting does not stop, shorten the servo horn."

06-03-2008 06:25 PM

nmrs
Senior Heliman
Location: Austin, TX

I have the Align BL-35X esc which puts out 6 volts, so I need to step it down to not fry my tail servo (s9257). For now I have put the regulator after the gyro and before the tail servo. I could certainly move it before the gyro (401) and just run both at 5.1v. Is there a preferred place to put the regulator, before or after the gyro? I guess its not going to hurt the gyro to place it after the regulator, so I will try moving it. If that doesn't fix things, I will try shortening the servo arm. The only reason I hesitate to shorten the arm is that everything is lined up all 90* at center servo now.

06-03-2008 06:33 PM

kcass518
Veteran
Location: Manhasset, NY - USA

Yeah, I wish someone else would jump in here to confirm these things, but I'm sure my 450SE came with a similar esc, and no one I know puts a regulator in there. The 35X lowers the LiPo voltage to a maximum of 6 volts, so it really should be not necessary to add a regulator. I think that they don't recommend running more than 6 volts through the gyro and servo, but I would think that up to 6 v would be okay. Out of curiosity, where were you advised that a regulator was necessary in this installation? If you're nervous about it, remove the regulator and just take a quick 'up and down' to see if things are better. Then learn whether the regulator is necessary.

Maybe you could do a new post on the Align 450 forum and just ask if a regulator is needed for the gyro/servo when using a 35X. I'd be interested to read the responses.

I understand you don't want to alter the servo horn when everything is lined up, but you could use one of the existing holes closer to the center, and, for the moment, not worry about it being exactly at 90 degrees just to see if it helps. First we have to iron out the hunting. Then you can make it pretty.

06-03-2008 07:37 PM

nmrs
Senior Heliman
Location: Austin, TX

Quote
Maybe you could do a new post on the Align 450 forum and just ask if a regulator is needed for the gyro/servo when using a 35X. I'd be interested to read the responses.

Good idea -- I just started this thread: http://www.runryder.com/helicopter/t436418p1/

Quote
I understand you don't want to alter the servo horn when everything is lined up, but you could use one of the existing holes closer to the center, and, for the moment, not worry about it being exactly at 90 degrees just to see if it helps. First we have to iron out the hunting. Then you can make it pretty.

I tend to agree. Will try moving the ball in some. For now I have moved the regulator to before the 401. I'll first go and try it like this. If it's no better will try moving the ball inward. I've also got some low RPM vibrations going on (http://www.runryder.com/helicopter/t436348p1/) that may be the cause of all this, so there's one more thing to check into.

06-03-2008 07:52 PM

kcass518
Veteran
Location: Manhasset, NY - USA

I rereread your original post, and it says that you can't get the tail to wag, so my thought of moving the ball link closer to the center seems unlikely to help (moving it closer to center solves 'hunting' or 'wagging' problems). I'll bet the regulator is causing some interference with the gyro. Also, have we been over the issues that are caused by having the gyro wires close to the cyclic/collective servo wires, and the issues of having any of these wires near the power wires to the esc & motor? You want to be sure these wires are as far from each other as possible. Even you could move them outside of the frame and as far apart as possible, just to do a quick up and down to see if there is any improvement. Again, fix the problem, then make it pretty.

06-03-2008 08:30 PM

nmrs
Senior Heliman
Location: Austin, TX

Yes this thread has gone through a few generations of tail problems

. At first I couldn't get it to wag. Now it will definitely wag. I tend to think right now my problems are probably vibration induced (http://www.runryder.com/helicopter/t436348p1/), so am trying to track that down. The not wagging is no longer a problem (i.e. now it will wag), so if I track down the vibration and it still wags, I will move on to moving the ball inward.

06-03-2008 08:39 PM

Blade_Master1
Key Veteran
Location: Canada

regulator goes before the servo
you need a regulator depending on the servo you are using

JM2C's :)

06-04-2008 01:26 AM

Blade_Master1
Key Veteran
Location: Canada

what mode are you running the ESC in ?

I have tail issues with governor enabled

also what ESC timing mode are you using, keep it set to med

JM2C's :)

06-04-2008 01:32 AM

nmrs
Senior Heliman
Location: Austin, TX

Oh naughty naughty Blade Master. Now you're just confusing me

. Back on page 2 you said:

Quote
I have tried every mode on the align ESC for me I find my heli runs best in governor mode @ 100% throttle with tail servo horn set at the 2nd hole out 100% flat curve in governor mode with the 11t pinnion

Now you're saying you:

Quote
have tail issues with governor enabled

I switched from idle 1 throttle curve of 100 92.5 85 92.5 100 to governor mode based on your recommendation. Now my throttle is set at 90% across. I wanted to be sure governor had a little headroom so I didn't run it at 100%. I'll go back and compare throttle curve vs governor mode again tomorrow if the wind dies down. I'm a little scared to take it out today with a national weather service wind advisory going on here...

Quote
also what ESC timing mode are you using, keep it set to med

Mine is set to medium

06-04-2008 07:20 PM

Blade_Master1
Key Veteran
Location: Canada

Guess I should have said I am now having trouble in governor mode

I recently switched to a 13t pinnion

now I have a tail wiggle

JM2C's :)

06-05-2008 12:46 AM

Blade_Master1
Key Veteran
Location: Canada

AH HA

with the 13t pinnion governor mode was causing problem

now my esc is set to 1, 2, 2, 2, 3,

now my tail is locked in again

guess your esc setting could be affecting your tail

JM2C's :)

06-05-2008 02:01 AM

nmrs
Senior Heliman
Location: Austin, TX

Sorry I've taken such a while to update this thread, but I've been traveling a lot for work recently and haven't have much heli time. I've tried to get in 1 or 2 flights a day when I was in town, but haven't had much time for tinkering with the mechanics. Anyway, I've finally managed to solve the problems I was having completely (knocks three times on wooden desk...)

First, I think the most significant problem was that my tail boom was slightly bent right at the mounting block. I couldn't see the bend with the tail installed, but once I removed it, it was fairly obvious. So I changed out the boom. After swapping out the boom, there was no drift, I could get the tail to wag if I got gain up above 50, and the tail was kicking out a bit (15 - 20 degrees) on full collective. This was using the round wheel that came with the 9257. This is basically how I had left it around June 3rd. I had swapped out the tail then, but forgot to document that in the thread. You can see the new tail boom (carbon fiber this time so it will break, not bend) and ball mounting position in the photo below:

I left it this way for a couple of weeks or so as it was definitely flyable. Yesterday I had a bit of free time, so I decided to go back to the star wheel so that I could move the ball a bit further out from the servo center. This was suggested by quite a few folks:

speeddemon370:

Quote
Have you tried mounting the slider farther out on your servo horn?

Zaneman007:

Quote
2) increase the mechanical gain on the servo.

Helimatt:

Quote
My 9257 worked best (on a MiniTitan, not trex, haven't tried it there yet) with the ball further out on the arm, not closest in.

As you can see, with the servo centered, the angle of the rod to servo is now less than 90 (these photos are old ones taken before I swapped out the boom, but it basically looks the same now):

But it is approximately 90 for most of its travel now:

But the most important thing is probably how it flies, not how it looks. I had tried this before, but only with the old bent boom, so it wasn't really a valid test. So after changing the servo wheels I took it for a test flight. I flew a couple of batteries and tail held rock steady, even on full collective.

Anyway, thanks to everyone for all of your patience with me and your help. I doubt I ever would have figured this all out on my own.... Well I probably would have swapped out the bent tail boom once I found it, but doubt I would have ever thought to fiddle with the distance from servo center to ball center, so thanks again.

06-17-2008 04:25 PM

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Beginners Corner > how much gain is too much?

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