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HelicopterMain Discussion › blade fluttering sound when adding collective???? help
03-12-2015 03:51 AM  3 years agoPost 1
emederos

rrApprentice

Miami, Fl Dade

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my heli had a tip over and blade strike a week ago. it was flying perfect before the blade strike. i went a head and changed the main shaft that was bent and checked the feathering shaft spinning the screw on one grip and checking for wobble it seems fine. changed the main gear and spider tail gear. now it spools up fine until the head speed goes to about 75% and as i give it some positive pitch it flutters loud and scared me do i hit HOLD , its not even taking off I'm imagining it may be the main blades that i bought are off balance?? what else can it be causing this flutter sound???

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03-12-2015 03:59 AM  3 years agoPost 2
Roamer

rrVeteran

Albuquerque, NM

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Did you balance the blades? I don't trust ANY blades to be balanced until they have been through my Koll Rotor Pro.

And I have to ask a question that WILL insult your intelligence! I'm only doing it because the EXACT same thing happened to me! When I was spooling up my heli (after a crash and rebuilt, just like you), it would get up near the set speed then the head went WAY out of track in an instant. I thought it was going to hit the boom it was so far out. It took a bit of looking and testing to find the problem:

Did you install the blades backwards (training edge forward)????

-RRRoamer

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03-12-2015 04:06 AM  3 years agoPost 3
icanfly

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ontario

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spin both sides of the feathering shaft. static balance the blades to match them near to perfect as can be expected, spool again and things should be equal. This question comes up from time to time, reminds me of the blades you see on the heli in my avatar, those I would get the same problem as you describe until I balanced the blades properly.

Check the tracking as well. simple stuff.

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03-12-2015 04:20 AM  3 years agoPost 4
emederos

rrApprentice

Miami, Fl Dade

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The leading edge of the rotor blades are matching with the leading edge on the paddles, and spinning the right way, when I add collective the leading edge goes up, I don't know what else to check. I put my stick to mid stick and hit UI while its spooling up its fine until it gets to about 75% throttle then begins that heavy flutter sound and its when I flick hold because it just doesn't sound right

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03-12-2015 04:26 AM  3 years agoPost 5
emederos

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Miami, Fl Dade

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The new rotor blades I bought are tough to fit into the blade grips, not like my old ones they slide right in....I don't know if this has anything to do with it but my old blades also have some plastic shims to make them snug in the blade grips...I know I need to balance the blades and swap out the feathering shaft after those 2 things if it continues can something be off on the flybar? I look at it it seems perfectly straight. After the blade strike I did have to tighten one paddle because it tilted down about 10 degrees. I look at it and it seems straight . Is there a way to check the flybar paddles to ensure they are perfect?

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03-12-2015 04:30 AM  3 years agoPost 6
Funky Trex

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Westerville, OH - USA

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Check all of the head parts and make sure nothing has come loose. This is a common problem if a ball/link is loose in the head or one of your links is cracked.

Also, what model heli is it? What brand/size blades?

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03-12-2015 04:38 AM  3 years agoPost 7
emederos

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Miami, Fl Dade

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I did check the parts and links everything seems fine. The blades are 430mm carbon pro blades DY-4301Y can be seen on eBay (yellow and black carbon blades)

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03-12-2015 04:38 AM  3 years agoPost 8
gologo

rrKey Veteran

Sedalia, Mo USA

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As mentioned above, did you sight the tracking on liftoff? If the F spindle
is bent, or links just way out of adjustment, will definitely cause a flutter sound. And make sure your paddles are straight horizontal all the
way around, as you spin the head around by hand, w. cyclics neutral.

Also were your replacement blades quality, name brand? I have ran into soft
warped blades in the past that were junk and acted just like what you
describe.

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03-12-2015 04:42 AM  3 years agoPost 9
revmix

rrKey Veteran

NJ

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tip & track
different blades ~ different sounds

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03-12-2015 04:43 AM  3 years agoPost 10
dkshema

rrMaster

Cedar Rapids, IA

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When you replaced the feathering spindle, did you reassemble the head properly -- making certain that you put the inner and outer thrust bearing races in their correct positions? Are the rubber dampers sound, and did you lube them?

Did you damage any gears in any of the servos?

You may have bent the grip where the blade pitch arm attaches, or you may have bent the pitch arm itself.

Check all ball links up on the head, as well, and the linkages, you may have bent/damaged one or more.

If you rebuilt the head, you should go back through proper head setup.

If this thing is going out of track -- which may be the cause of the flutter sound -- it's an indication that something in the head above the swashplate is wrong, allowing a softness or spongy response to cyclic/collective pitch control.

As for your flybar paddles. Level the swashplate. The paddles should be level, parallel to each other, and to the swashplate, this isn't rocket science.

You would have had to have purchased some pretty cheap/cheesy blades these days to be horribly out of balance or be warped/bent. The majority of "name brand" blades these days are well matched out of the box. Blades out of balance won't cause a fluttering sound, by the way.

What kind of heli, by the way.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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03-12-2015 04:52 AM  3 years agoPost 11
emederos

rrApprentice

Miami, Fl Dade

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It's a 500 esp in a scale fuselage the one on my avatar. I had the same blades on it befor and it flew great. I believe it's the links that may have the pitch off on both blades. I ordered a digital pitch gauge so when it comes I'm going to check the pitch angle on both blades when in mid stick Im almost certain this is it because I had to change one servo and kind of gave a couple turns to one link only and eyeballed it to get the servo back on. If one blade link is a bit off the other this should throw off the balance and tracking I assume.....

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03-12-2015 05:00 AM  3 years agoPost 12
JEEPWORLD2002/2

rrKey Veteran

Blue Bell, Pa

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That's probably it each blade has its own pitch and probably needs to be adjusted then track them in a low hover n get then dead on or it will cause you un needed grief also check for broken links ends pop each end off n check them carefully. It's quiet easy to damage stuff on simple tip over. Any chance u can post a utube vid so we can hear n see it. Also how is your servo movement ?? Some times u can break the horns n or damage gears ?

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03-12-2015 05:05 AM  3 years agoPost 13
revmix

rrKey Veteran

NJ

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check tip track, out of tracking is noisy

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03-12-2015 02:24 PM  3 years agoPost 14
emederos

rrApprentice

Miami, Fl Dade

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Would really tight blade grips cause this issue?

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03-12-2015 02:40 PM  3 years agoPost 15
dkshema

rrMaster

Cedar Rapids, IA

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I had to change one servo and kind of gave a couple turns to one link only and eyeballed it to get the servo back on
Balance isn't your problem.

I believe you need to understand proper rotor head setup, then go through your heli methodically to get the linkage/servo geometry correct.

If you're replacing a servo with the same kind, having to adjust a ball link "a couple of turns" is not par for the course.

Blades in grips being too tight CAN be a problem as the blades are required to be able to lead/lag a bit on the attachment bolts during flight.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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HelicopterMain Discussion › blade fluttering sound when adding collective???? help
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