N7 head bobbles

[eobie]

So I've got about 50 flights on my n7. I have had an elevator and aileron bobble the whole time, but I loved flying it I didn't really ever bother to tune it out on the vbar.

Well I went to the field today on a mission  to get rid of it. Blades were super tight due to temp change so I loosened a bit. I still run my blades rather tight for autos.

Anyway, I'm running the stock head shims and haven't changed them out for thinner ones yet. Had head gain at 90.. Giving quick aileron or elevator input resulted in a bounce. I reduced the gain to 80 and the elevator was mushy and no bounce... No effect on aileron.

Have any of you guys had this issue? Should I try thinner shims in head??

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[eobie]

Guess i omitted that I'm using vbar.

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[Jon Mills]

First thing to do would be to figure out if the tightness of the blade bolt is causing, or what its effect on the problem is.  I noticed on my N7 it really doesn't like tight blades.

[Kevin Feil]

Is it safe to say you are having the issue in all flight modes? Can you be more specific? Also for grins, loosen the blades a touch more for troubleshooting purposes. You will be surprised also if the torques (tightness) aren't even between the two blades. It is not uncommon to have that issue at low head speeds, I think I would really look close at your Gains. Keep dialing back the numbers after you adjust the blades of course. Focus on one piece at a time. You change everything at once an it gets a bit hard to distinguish what fixed what. Good luck!

K

[eobie]

Hopefully I can out in the next couple days... I'll try loosening the blades. It is across all flight modes.

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[Kevin Feil]

And I guess it's safe to say your Rpm range is around 1,700 to 1,950 from normal to Idle up 2? I personally would recommend the Blade Tension first. The fact that it is doing it in all modes kinda points to that as opposed to a Gain issue ( of course not ruling that out) simple things first.. Of course this is based off my experience personally and what I have seen in the Field. And I know this is going to be a dumb question but I have to ask, I assume your running a Matched/ balanced set of blades. ( not pieced together) also have you had any crashes that could result in a spindle or main shaft being slightly bent or anything for that matter being compromised??  Also with you saying that you have logged over or just at 50 flights with the wobble present, really make sure all hardware and overall mechanics are good and tight and to spec. Helicopters regardless of RC OR FULL SCALE don't take that very well especially an extended length of time. Keep us posted 

Kevin

[eobie]

Yep. Idle up 2, is at 1950.. Just to be clear, its not a wobble like a low headspeed gain issue. Its a bounce when a quick cyclic input is given..

So with that said I've found the issue. KDE boom support, the epoxy broke loose and I lost a pin. When I said that I've had it there for 50, flights I should have been more clear. You wouldn't see it unless I purposely tested for it.. I had a busted boom support before. Got one again. Re did the end with new epoxy and this time pulled all the pins out of the KDE boom supports and am now installing pins long enough to use locknuts on the ends. Now just gotta test...

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[eobie]

Yeah reading my.original email....I really wasn't all that clear.

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[Kevin Feil]

Good to know your all squared away! Good luck Brother!

Best Regards,

Kevin