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HomeAircraftHelicopterMain Discussion › Frightening flutter after repairs R50v2
11-03-2004 06:10 PM  13 years agoPost 1
gigi

rrVeteran

Port-au-Prince, Haiti

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I've fixed my Raptor 500v2 for the 5th time this week-end. (October was a rough month!)

I've fitted Mavrikk wood blades while waiting for my new carbons to arrive. I've epoxied the blade grips on, and balanced the blades. The heli hovered well, but after a short flight, I heard a truly frightening fluttering sound It didn't last more than a second, but it happened twice more in the time it took me to set it down. The whole heli shook mildly when the sound was occuring.

The main shaft and the spindle are new, all the linkages are tight, and blades were tracking well prior to lift-off. I don't think I was over-reving them, although I did not have a tach to make certain. I can try to lower my head-speed, but I'd really like to find the cause of this impending doom before it actually happens. Anyone ever had their Raptor 50v2 act up like that?

Thanks for any feed-back!

Gigi

My heli spending has gone way down since I got a Honda 919 :-)

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11-03-2004 06:26 PM  13 years agoPost 2
DRusso

rrNovice

Vineland, New Jersey

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With 5 crashes in a month you could have done damage in areas that you may have overlooked. Start first with the ball links (balls) themselves especially the ones on the blade grips. If they are bent or loose the least bit this problem may occurr. Good luck.......


Damian

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11-03-2004 06:39 PM  13 years agoPost 3
concept1

rrKey Veteran

Youngstown, OH

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check all your links for "slop" check all your arms for Slop. sounds like the problem I had when I had slop in my head it would go in and out of track with high head speed it was so bad heli shook terribly bad. verify your head speed. to correct mine I used loctight and glued all the bearing bushings in my bearings and then glued the bolts in the bushings to eliminate the slop, 2 gallons later still rock solid.

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11-03-2004 07:05 PM  13 years agoPost 4
Ringding

rrApprentice

Austria

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Was it not just the blade covering coming off? This makes a very ugly noise...

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11-03-2004 07:08 PM  13 years agoPost 5
BarracudaHockey

rrMaster

Jacksonville FL

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Do a search on WOOF

Andy
AMA 77227
http://www.jaxrc.com

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11-03-2004 07:58 PM  13 years agoPost 6
gigi

rrVeteran

Port-au-Prince, Haiti

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Will go through it with fine-tooth comb...
Thanks, guys.

I'd like to point out that I've only crashed 4 times in october! The first crash was mid-september

I will check the covering, but it seemed OK. And I've replaced every single busted link. (Probably 6 or 7 so far, 3 of which were in a single crash, which separated the entire rotor-head from the main mast.)

I think I'll pop in those fiber-glass blades instead of the woodies for the next flight, if I don't find anything else to pin the noise on.

Gigi

My heli spending has gone way down since I got a Honda 919 :-)

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11-03-2004 08:58 PM  13 years agoPost 7
Arthur Lee

rrNovice

Singapore

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I've had the same problem...it went away after I oiled the damper and the spindle shaft which goes through.....

try?

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11-03-2004 09:10 PM  13 years agoPost 8
Darksider

rrKey Veteran

Derby United Kingdom

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might sound too simple but you did make sure that both thrust bearings were installed the correct way around didn't you??

Gareth

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11-03-2004 09:35 PM  13 years agoPost 9
rcadd1ct

rrElite Veteran

Richardson, Texas

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check the washout arms.

They loosen up and cause issues.

-RCA .......... Making Cuisinarts Fly!!!!!!!

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11-04-2004 03:00 AM  13 years agoPost 10
SuperHeli

rrApprentice

Milpitas, CA, USA

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Try harder dampers and bell mixing ratio, it should change the head dynamics and may avoid exciting that particular mode. I have problem with a particular brand blades but I don't think it's a blade issue, it's probably just a issue with a particular combination.

Ben

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11-04-2004 02:26 PM  13 years agoPost 11
gigi

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Port-au-Prince, Haiti

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Will swap blades tonight...
I never had a problem with the first set of those blades, but the mixing ratio was on the lower of two settings, and I was running the blue durometer dampners. The current setting is the 3D hole on the mixing arms, red 80 durometer dampners, and probably I was turning them a wee bit too high.

The spindle is lubricated, it's the only way to put it in, as far as I'm concerned. The trust bearings were never removed from the blade holders, and I know they're in there the correct way. I'll double-check the mixing arms and everything else, but I'll swap out the woodies for the KSJ's tonight. I can't wait 'till I get my Mavrikk carbons. I never had any problems with those.

Thanks for the tips, guys! They're appreciated.

Gigi

My heli spending has gone way down since I got a Honda 919 :-)

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11-04-2004 02:30 PM  13 years agoPost 12
frogbaiter

rrApprentice

Oxford UK

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I had something similar happen recently - a few times the blades fluttered for a few seconds then it went away. Finally, I lost most of the control around midstick of the collective pitch - the servo had stripped teeth! Eeeek..... managed to land it safely if a bit hard, and now I have nice new servos in.


Steve
www.helicollective.org.uk

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11-04-2004 06:32 PM  13 years agoPost 13
tofly90

rrNovice

easton maryland

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blade flutter
I had same problem after betting my head against wall trying to find discoved it was heat shink covering on blade would seperate from blde in flight change shape of airfoil on ground seemed tight cut old covering off recovered with adhesive trim sheet problem gone

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11-04-2004 07:58 PM  13 years agoPost 14
Tohme

rrApprentice

Sao Paulo - Brazil

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I had many flutter problems with my Raptors and the problem is all the same.
The blades.
Check the chord C.G.. The Raptor head (and Hirobo, too) doesn´t like the CG pointing to the blade trailing edge. You have to use blades with neutral CG or pointing to the leading edge of the blades

Tohme

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11-04-2004 08:03 PM  13 years agoPost 15
ZIGZAG

rrApprentice

CTRL FL

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Hi
Just a thought
Check all the ball bearings especialy the ones that are running @ engine speed & the main shaft one may have a flat spot or be contaminated
ZIGZAG

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11-05-2004 04:43 PM  13 years agoPost 16
SLiebl

rrApprentice

Lancaster, PA - USA

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How about too much head speed for woodies?

-Steve

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11-05-2004 05:21 PM  13 years agoPost 17
gigi

rrVeteran

Port-au-Prince, Haiti

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Problem solved!
The first thing I did was swap out the woodies for the KSJ's. Then, when I went to take off, it occured to me the rotor rpm was very high. Looking at the pitch curves, it seemed to me I had higher values in there than I was used to seing. So I put a pitch gage onto the blades, and sure enough, I was running low pitch, despite the high numbers. Itraced that back to a swap of the short links which go from the mixer to the blade grips. I had busted the factory ones, and replaced them with replacements fabricated from cut-off normal-lenght links.

So now, with proper pitch, and normal rpm, and the KSJ blades, no problem whatsoever, it flies like a dream once more. I am sure there wouldn't be any problems with the woodies, now that the rpm are back where they belong.

Thanks for the help, guys!

Gigi

My heli spending has gone way down since I got a Honda 919 :-)

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