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HelicopterMiniature Aircraft Whiplash & Fury 55 › Skid wobble with lower head speed
03-12-2006 12:43 AM  11 years agoPost 1
Dana54

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Wilmington,NC

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I rebuilt an SE after a bad auto. Blades chopped off the boom. It has a vibration now and I noticed that if I slowed the head down (maybe to 1000 rpms) that the skids wobbled a lot. I put on a new main shaft, spindling shaft,blades, boom,torq tube,tailbox,etc. At normal hovering head speed there is foaming in the tank,vertical and horizontal fin vibration. The engine is running fine. I thought I would ask for some suggestions before I start tearing it back down. Thanks in advance. Dana

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03-12-2006 01:45 PM  11 years agoPost 2
T Koffler

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Cayuga, NY 13034

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What about your blades? Matched set? You did not mention blade track... Oh yeah.... Is your tail rotor in phase with your main shaft?? I would think that you would be able to solve a little prob like this on your own...

Seriously though.. I wish I was there! I miss flying with'ya..

P.S. How's the twin???

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03-12-2006 02:12 PM  11 years agoPost 3
Dana54

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Wilmington,NC

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Hey

It's comments like this that makes me glad you moved away. Hope your doing well. The weather is not very good today..82 sunny slight breeze off the ocean. How's the snow ! ! !

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03-15-2006 04:58 AM  11 years agoPost 4
fran

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HONEA PATH, SOUTH CAROLINA

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What I've seen over the years of FAI and slower head speeds are a couple of things...

When flying you may need to seriously recheck flybar balance...not just distance being equal from arms to flybar paddles; but actually remove the head and support the grip on two water glasses and check to see if flybar with paddles are equal in length and blalance out...if not you may need addon flybar weights (check Curtis' ship and you'll still see them on his comp birds). Second is just a matter of matching collective to head speed (not trying to be flip but it's true when your hovering around 1250 to 1550 RPM on the head.

Just rying to help not knowing it all...just around 30 years on choppers.

Hope this works for you!

Fran

FRAN SR. ( FAI-F3C)

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03-15-2006 11:18 AM  11 years agoPost 5
Dana54

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Wilmington,NC

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Thanks for the help Fran.

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03-15-2006 11:36 AM  11 years agoPost 6
airdodger

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Johnston USA

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Did you use new dampner O rings, check the thrust bearings they can cause tracking problems that lead to vibration. The vibration does sound like a fan alignment problem if you have foaming in the tank, or the engine is not adjusted correct. The wobbling of the skids is most likely because the headspeed is to low for the stiffness of the head at that rpm. Chris

Chris

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03-15-2006 03:52 PM  11 years agoPost 7
Dana54

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Wilmington,NC

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I don't think that I used new dampner O rings and I remember wondering how many shims to use for the the metal head with metal grips? The fan was mounted by someone else so I should check it. Thanks for the input Chris. Dana

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HelicopterMiniature Aircraft Whiplash & Fury 55 › Skid wobble with lower head speed
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