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Home✈️Aircraft🚁HelicopterHIROBOOther › freya x-spec head(severe blade flutter)
09-09-2006 11:06 PM  14 years ago
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RICH.L

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gentry arkansas

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freya x-spec head(severe blade flutter)
I need help bad!!
i just put my evo 90 with x-spec metal head back together after a crash caused by my tail control rod breaking.
i am having severe blade flutter to the point i think it is going to explode when it happens!
I bought the heli used and have barely 3 tanks of fuel run through it at this point,but can't figure out why the blades flutter so bad!
i replaced the mainshaft,flybar rod,and the feathering spindle.
i tried a set of helimax c/f blades and it fluttered very bad,so i sent them back and bought a set of 690 v-blades and the flutter is just as bad.
the blades are tracking perfect but when you get into forward flight and start to flip,turn or roll that is when the flutter occurs.
i am going to check the thrust bearings to make sure they are in right(this is my first hirobo heli)
i was thinking about doing the blade grip flip that i found in one of my searches but not sure if that would help?
i have a few pictures posted and it looks like one of the arms off of my metal blade grip may be bent some,to get the proper pitch i had to lengthen the rod(could that cause any problem)?
i had it at the flying field today and everyone was pretty much stumped just like me.
rich

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09-10-2006 12:31 AM  14 years ago
hellflyer

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Staten Island NY

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what head speed are you running ????????The first step in gettin help is admitting you have a problem ( yes I am addicted to helicopters )
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09-10-2006 12:34 AM  14 years ago
RICH.L

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gentry arkansas

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headspeed is 1900 in idle up 1.
1750 in normal mode.
rich
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09-10-2006 12:38 AM  14 years ago
hellflyer

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Staten Island NY

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Does it flutter at 1750 alsoThe first step in gettin help is admitting you have a problem ( yes I am addicted to helicopters )
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09-10-2006 12:55 AM  14 years ago
hellflyer

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Staten Island NY

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sounds crazy but did you check the main shaft before you installed the new one could be bent also did you check your feathering spindal
and do you have the manual you may have to check the alinment
with the washout and the swashplate also called phasing
The first step in gettin help is admitting you have a problem ( yes I am addicted to helicopters )
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09-10-2006 02:07 AM  14 years ago
Kinger

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Granville, OH

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Thrust bearings would be a good thing to check. I'd also check the hub. Sometimes it can bend in a good crash.
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09-10-2006 02:48 AM  14 years ago
Quickster

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Victoria, Australia

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looks to me that in the photo's that the pitch arm on the blade grip is bent in towards the head block. The stand off ball should be at 90 degrees to the spindle shaft. I think that would probably cause the flutter.
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09-10-2006 12:49 PM  14 years ago
mrNoodles

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Borlänge, Sweden

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Looks bent! /Fredrik
'Hm now I just have to find out where to connect the GV1 sensor to the Jazz80 ESC.
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09-10-2006 04:48 PM  14 years ago
jkelly

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Bedford, PA

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Perhaps the spindle or feathering shaft is bent, the main shaft and main hub generally result in a constant vibration if bent. That grip looks bent in the picture.

Just curious, why is your radius block so low?
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09-10-2006 05:48 PM  14 years ago
ncarbon

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Kalispell Montana

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Grip Bent
I agree, in the photo the spacing looks uneven between the grip and head.

Ned
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09-10-2006 08:06 PM  14 years ago
RICH.L

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gentry arkansas

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well i ended up flipping the grips on the x-spec head so it will be more like an evo head.(reset all my pitches)
i pulled the spindle out and checked it for straightness(was o.k.)
the thrust bearings were in proper but they don't look o.k.
one side has a metal ring around the balls of the thrust washer,but the opposite side doesn't have the same ring holding the balls in place.(i wish i would have taken a picture of it)
i don't know if that is the way they are supposed to be or not!
although both sides are like that.
i also tweaked the bent arm back even with the other one,if that cures it then i will just order two new arms for it.
i would like to try it out today but winds are gusting over 20 mph.
i know a 90 can handle the wind but i have not even had a chance to get used to it yet!
all the shafts aare new and in a hover there is no vibration and seems very very smooth.
rich
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09-10-2006 08:19 PM  14 years ago
RICH.L

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gentry arkansas

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i am also running 7.75 gear ratio with the os 91sz-h and hatori pipe.
to get the engine into it's power band i need to be closer to 1950 headspeed.
that is not too high of a headspeed to run is it?
i was used to 2000 on my hiper raven 50
rich
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09-10-2006 08:28 PM  14 years ago
Kokamo

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Liberty Hill Tx

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one side has a metal ring around the balls of the thrust washer,but the opposite side doesn't have the same ring holding the balls in place.
Thats the way they are supposed to be.

Yes, 1950 is ok, but I wouldnet go past 2k.

Joe
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09-11-2006 04:55 AM  14 years ago
mrNoodles

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Borlänge, Sweden

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7.75 is low.

Have that bladeholderarm replaced once you´re at it, it sure looks bent.
/Fredrik
'Hm now I just have to find out where to connect the GV1 sensor to the Jazz80 ESC.
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09-11-2006 05:41 AM  14 years ago
RyanW

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Edmond, Oklahoma

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If it was a hard enough crash to replace the mainshaft/spindle you most likely need to replace the radial bearings in each blade grip. You probably need to replace the thrust bearings as well. What happens when they are bad is that under load a grip will get "stuck" in the bad spot of the bearing, causing a differnce of pitch between the blades. This will cause them to go out of track, flutter and cause vibration.

-Ryan
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09-12-2006 02:33 AM  14 years ago
RICH.L

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gentry arkansas

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well everyone,i took the heli out tonight and started flying in normal mode at 1750rpm and no blade flutter.
after a few minutes of that i went into iup1 at 1900rpm and did flips,loops and rolls and even did a few tic-tocs.
still did not hear any blade flutter and seemed to be o.k.
i will find out for sure when i go up to the flying field over the weekend,it is kind of hard to concentrate on flying and trying to listen for any abnormal blade noise.
before i couldn't even make a turn without the blades making that flutter sound.
man does this thing climb now,i don't know if that is because of flipping the grips or the engine is starting to get broken in,but i sure do like it!
this was my first actual full flight where i could get a feel for it,this heli fly's pretty nice.
rich
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09-13-2006 12:07 PM  14 years ago
RICH.L

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gentry arkansas

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09-13-2006 12:38 PM  14 years ago
mrNoodles

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Borlänge, Sweden

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#0414-227 comes with the SZZ-II head./Fredrik
'Hm now I just have to find out where to connect the GV1 sensor to the Jazz80 ESC.
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09-18-2006 02:44 AM  14 years ago
RICH.L

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gentry arkansas

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finally got another good day to fly again,took the heli up and burned up about 1/3rd tank of fuel just doing flips and rolls and then the tail starts to piro on me for no reason!
the tail stopped and held for a moment and then took off again,headed for the ground inverted still spinning like mad.
about 3 feet off the ground the tail stopped again and i was able to pull enough negative to get it to stop and then flipped it upright and landed it.
right when i was landing and hit throttle hold you could see the tail trying to spin.
the servo arm was all the way to one side,and even when you moved the stick to bring it back and then let go of the stick the servo would return to that same side.
must be something wrong with my gyro?(gy601)
a lot of people saw the near crash and everyone was commenting on how nice of a save it was( i couldn't beleive it myself!)
one of these days i am going to get all the bugs worked out of this heli and actually get to fly it!
rich
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09-19-2006 01:17 AM  14 years ago
chris daws

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World Traveller, Back in Taiwan

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metal head bent arm and vibration
If the lever on the blade holder is bent as seen in the picture it will ahve an effect on the pitch on that blade, if the rod is changed to make the pitch correct at the zero position then at say +10 on that blade you will find that the pitch on the other blade will be less since the distance between the ball on the lever and the centre of point of rotation is less than the original, this results in more pitch being applied at the grip with the bent arm. This is why you get vibration, if you hover and look you will find that the tracking is wrong, if you correct the tracking at hover it will be wrong everywhere else in the pitch range resulting in vibration. Reversing the grips will not change things nor will changing head speeds. set any pitch and check with pitch gauge on both blades, they will not read the same at all pitch points.
Just my thoughts but mechanically this is what happens

Chris
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