Head Shake unresolved on Goblin 570

[Danny Dugger]

Can anyone explain why I can not see the pictures that was supposedly listed in curmudgeon's reply?

I can't see them on my phone but I see them on my PC.

[Grees01]

Hi, and you can see the pictures that you referenced in your first post?

[Grees01]

Wow, that's weird, internet explorer 11 or firefox 42.0 no pics. Is there something you have to click on?

[Danny Dugger]

I use Chrome.
On my PC and on my phone.

[Grees01]

No luck, tried with chrome too. Are the pictures listed within the post, or external to the post?

[Grees01]

Curmudgeon, you ran a set of rail 556 mains on your goblin right? How did that work out compared to the stock SAB blades?

[curmudgeon]

I set up the Goblin 570 to run on 6S. My LiPo's came back substantially cooler with the Synergy 556 blades than with the stock SAB 570 blades.   However, the Synergy E5 autos a lot better than the Goblin 570 with either the 556 or the 570 blades.   The tighter I adjusted the tail belt, the faster the main blades would stop spinning during autorotations. 

[Grees01]

Thanks Curmdugeon, did you have any issues with blades being out balance or any QC issues with your blades?

[Grees01]

The AWS 200gm scale showed up. I removed the main and tail blades and checked balance. After removing tape there was a weight difference of approx. .11gm on the main blades. 120.31 and 120.42. Re balanced and according to the scale, identical in weight. 120.41 (the scale does move around a point or two). Tail blades were quite close, 47.3gm and 47.1gm. I left it alone. Probably did 10 flights Sunday. Still shaking. My wife took a video with my phone but one of the settings was wrong and the video is not usable. Weather is lousy right now. Blowing like no tomorrow, and about to rain. Really bugging me, that I can pin down the cause of this problem. Any chance that the stock servo horns that came with the servos which are a bit flimsy, (they have some flex to them) could be causing me an issue?

[Danny Dugger]

Any chance that the stock servo horns that came with the servos which are a bit flimsy, (they have some flex to them) could be causing me an issue?

I don't think so. Especially if damping affects the RPM range of the wobble. That said, plastic does flex and I do prefer to use more substantial horns than the regular plastic ones. The carbon reinforced ones work well as do secraft v1s and both should help to reduce or prevent gear damage in a crash.

Did you try running a higher headspeed? How tight are your blade grips? Perhaps you could try lightening up the clamping force on them a little and make sure they're about equal. Don't run them loose, but they don't have to be insane tight either.

[Grees01]

Hi Danny. Thanks for the reply. I haven't tried changing the head speeds. Really I am close to the upper limit of rpms on a 6s system, at least according to the manual. It shows 2450 being the max with a 6s system and that is with a slightly bigger speed control than I have. I could maybe squeeze 100 more rpm out of it with a 23 tooth pinion but I would be maxed out. Then anything lower puts me in the rpm range that I am currently having trouble with. I could go lower, 1800, 1900,2000, my current normal mode is 2100, with iu1 2200 and iu2 2300. That's an option. I feel uncomfortable flying it with the wobble. Seems like it has to be hard on all the components, bearings, ect, ect. Does anyone know anybody here locally (Los Angeles CA area) that I might be able to meet with and have a look at this thing together. I know its very difficult to diagnose problems remotely. Again thanks so much for you help and feedback.

[Grees01]

Sorry forgot to mention blade grip tightness. I have tried it quite tight, normally tight, a little loose, tightening them up pretty tight after the heli has spooled up and then back down, and nothing that I have tried with regard to blade grip tightness has eliminated the wobbles. 

[Grees01]

Here's a few pictures for whatever it might be worth. I didn't want to post a bunch of pictures on your server so there listed here on Google pictures at the bottom last 6 images. These are from this morning.

https://goo.gl/photos/NK76GitWpSrx8qiL9

[Mike Spano]

get your head speed up to around 2500, and fly the crap out of it for 10-15 flights and see how that goes. I have a few friends that have these helis, and they fly them around 2500 or so and they don't have this problem, even with BK servos, so I would definitely recommend you bumping the hs up to there, and breaking the dampers in good. if there is still an issue, then lets dig deeper. what you think?

[Grees01]

Hi Mike, thank you for your reply. Well, I could try. I'm not sure how much more overhead I have left on the esc. I checked my settings for governor and I made a mistake. I'm at 2200, 2300, 2400, currently. Ikon is controlling the governor with the addition of an external speed sensor. Ikon software doesn't tell me where I run out of room or max out, I can type in any value I want (5000 rpm) and no warnings!. If I choose to have the Castle Talon control the governor, I'll get a warning about overhead when I set the value to high. The manual seems to indicate that 2450 is the max speed possible on 6S with a variety of motors and speed control combinations, take a look at the attached manual page a post or so back. So really I'm not sure what to think???