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HelicopterHIROBOOther › Wobbling X-Spec
12-21-2003 04:51 PM  13 years agoPost 1
dneisler

rrNovice

Reno, Texas

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I have brand new X-spec that we test flew yesterday. Ran nice, but had a wobble side to side when we would flip in t idle up, around 1750 RPM. Tail is not really moving, it is holding pretty well. I am running a YS91 and it has now 2 tanks thru it. This is my first 60/90 machine so I am kinda at a loose here. Someone said it may be something to do the dampners? What do you guys thing.

D.

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12-21-2003 04:59 PM  13 years agoPost 2
sluggo

rrElite Veteran

Kitchener Ont

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dneisler we need more info on your setup! Like blades, paddles, pitch curves, radio gear gear ratio, head speed etc.

Sounds like something in the head but a new motor on break in can cause some nasty vibs as well.

Chris

Teambob00

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12-21-2003 05:04 PM  13 years agoPost 3
dneisler

rrNovice

Reno, Texas

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blades - TT 680
Stock Dampners
Paddles - Fully of weights
pitch curves - -4,2.5,+9 Idle -10,0,10
radio gear - JR 8103, 9252's, 9350, GY401, 9253
gear ratio Factory Ratio for 91
head speed 1550 Normal worked well.
1700+ I would say, wobble was there. Anytime I was hard on the collective and rpm would decay wobble would go away.

Not really a vibe to me, hovering tail in I could see the main shaft move side to side like 2 inches.


D.

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12-21-2003 11:10 PM  13 years agoPost 4
rcadd1ct

rrElite Veteran

Richardson, Texas

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Is it flutter?

Check the washout arms. Did you make sure you shaved on the sleeve to keep the arm from moving side to side.

Verify that all the servos are tight and the links have no slop in them.

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

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12-21-2003 11:19 PM  13 years agoPost 5
traderdave2

rrVeteran

Covington, GA

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The freya will wobble as you call it when the headspeed gets too slow. Move the head speed up some and the wobbles with be gone.

Check all the bolts on your frames and especialy the bolts in the head. The two bolts that hold the dampers should be checked for the first few flights.

harlan

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12-21-2003 11:26 PM  13 years agoPost 6
dneisler

rrNovice

Reno, Texas

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It wasn't head speed to slow I don't think, cause in normal at 1550 it was rock solid, but when flipped to idle up1 anad at 1750 it wobbled.


D.

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12-21-2003 11:34 PM  13 years agoPost 7
Dazzler

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Ohio

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How is your belt tension?

Daz...

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12-21-2003 11:38 PM  13 years agoPost 8
dneisler

rrNovice

Reno, Texas

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At first it was very loose, guess the cold got to it, but we tighened it before we flew. So I would say it was ok.

Again, Micheal Prewitt(Raptor Technique) was actually flying it for me. He didn't really know what to do as he is not familiar with the Freyas.

D.

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12-21-2003 11:40 PM  13 years agoPost 9
V8Buggy (passed)

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USA

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Mine does it also, but just at certain head speeds. It doesn't seem to hurt anything, if I go up a little, or down a little, mine goes away. Also after I put silicon lube on the head dampers, it goes away for about 4 or 5 flights, but then comes back, but again just at certain head speeds.

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12-21-2003 11:46 PM  13 years agoPost 10
dneisler

rrNovice

Reno, Texas

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So does it sound like I just did not lube the dampners enough?


D.

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12-21-2003 11:58 PM  13 years agoPost 11
rcadd1ct

rrElite Veteran

Richardson, Texas

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I have pretty much the same setup you do. I fly @ 1450N, 1700 Idle1 and 1900 Idle 2.

Mine does not experience any of what you are describeing.

Yes, Normal is a low HS. It reminds me not to go inverted in Normal. Been there, done that. Got the not so free new heli for it.

Another person had a spec and had issues at 1700 if I remember right. 1700 HS might be right at an engine harmonic.

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

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12-22-2003 04:03 AM  13 years agoPost 12
Jason Cummings

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St. Louis

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if your blade grip bolts are too tight it can cause a wobble like you describe at any rpm

Synergy Field Rep

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12-22-2003 01:39 PM  13 years agoPost 13
IMZ Caliber

rrApprentice

Chesapeake, VA USA

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how did you configure the rotor head. The wobble is an aerodynamic resonance. It normally has a headspeed range that it happens in except that its normally around 1500 and below so not many people push the head speed down low enough to get back out of it. Like more said the easiest fix is to runa different head speed. I ran 1800 and well above that on my setups with no issues with the resonance. Hirobo St. Louis is also correct that looser blade tension will helip minimize it also Except that most 3d pilots dont like loose blades. I fly with really loose blades my self. The more complicated way to try and solve the issue is changing the flybar and delta offset to again minimize the issue.

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12-22-2003 02:50 PM  13 years agoPost 14
dneisler

rrNovice

Reno, Texas

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I configured everything to be as stable as possible, and figured I would adjust to my feel from there.

D.

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12-22-2003 02:52 PM  13 years agoPost 15
MRC-Hirobo

rrKey Veteran

Edison, NJ

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Keep it simple and try to get both of the blade bolts the same tension. Going looser or too looses can also give you trouble.

Ideally the blades should not fall under their own weight when the heli is put on its side. Once you get that tension, you can tighten them up evenly if you wish to the point where the oscillation will not come in.

You may also have them too tight for the head speed you are running and that will give you the same results.

For the head assembly, make sure you also have some end play in the spindle. Just a little. Don't take out all of the end play with the included shims.

Jeff

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12-22-2003 04:24 PM  13 years agoPost 16
slant911

rrVeteran

Las Vegas, NV. Hirobo, Magnum Fuels, MAH

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THis may sound dumb, but, make sure the bearings are all the way seated in both blade grips. I had one once that was not all the way in (less than a mm out) and the heli would fly fine except at certain headspeeds. I finally disassembled everything and found the bearing "not seated".


John B. McNamara

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12-22-2003 10:14 PM  13 years agoPost 17
dneisler

rrNovice

Reno, Texas

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Thanks Jeff, and everyone. I will try to check some of these things and maybe fly Christmas day if all goes well. I will let you know the outcome.

Can't wait to get this one flying, I have only flown Raptors, so this should be a experience...

D.

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12-23-2003 02:22 PM  13 years agoPost 18
dkshema

rrMaster

Cedar Rapids, IA

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dneisler -- all flights are an experience...it's just whether or not they are pleasant ones!

When you get your Freya sorted out, you'll like it.

Dave

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12-24-2003 11:07 PM  13 years agoPost 19
dneisler

rrNovice

Reno, Texas

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Well I loosened the blades and tightened them today. Also noticed my Paddles where not perfectly aligned also. But after correcting and trying both I still have the wobble. Didn't have alot of time, but I will hopefully get to test more and try the other advice everyone has given me.

What is breakin time on the YS91? I have 3 tanks now?


D.

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12-25-2003 01:25 AM  13 years agoPost 20
FLYHOBO123

rrApprentice

B'ham AL.

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Lube

Lube the dampners, This will help if it doesn't you most likely have muffler bearing problems Just kidding
Don Wade

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