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HomeAircraftHelicopterMain Discussion › clutch/fan run out, what is this?
03-03-2008 08:56 PM  10 years agoPost 1
Dilbeck

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Springdale Arkansas

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Ive heard talk about highpoint balancers and have one now. Also seen here and there about the (run-out) on the fan should be a certain amount. What does it mean and how do you measure/achieve this?

Clint

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03-03-2008 09:00 PM  10 years agoPost 2
BarracudaHockey

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Jacksonville FL

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A device called a dial point indicator.

Here's an article about it
http://www.raptortechnique.com/clutchinstall.htm

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

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03-03-2008 09:01 PM  10 years agoPost 3
fergus

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Ireland

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Its the alignment of the fan on the shaft and is checked with a dial gauge or dial indicator. A bit of a luxury item but can be handy if you have vibration issues.

Regards

Fergus

Regards

Fergus

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03-03-2008 09:26 PM  10 years agoPost 4
Dilbeck

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Springdale Arkansas

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Thanks, read the article and seems to be a little picky unless all are out of round. Is this normal and would you expect a noticeable difference or is this just a wast of time?

Clint

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03-03-2008 09:55 PM  10 years agoPost 5
Jeff polisena

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westpalmbeachflorida usa

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Depending on what heli you are building some do not need indicating but most of your higher end helis (90's)need it

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03-03-2008 09:56 PM  10 years agoPost 6
BarracudaHockey

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Jacksonville FL

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Its just one of those things.

You can slap a helicopter together in 4 hours and it will fly or you can take your time and do things like greasing all the bearings, fan balancing, working each linkage for proper tension, get all the slop out, size your links, dial the fan and clutch etc.

If you ever have flown a helicopter thats been built/setup that way you will never go back to one thats thrown together. They are silky smooth, components last longer, and they are a pleasure to fly.

Its all in how much work you're willing to put into it.

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

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03-03-2008 10:06 PM  10 years agoPost 7
Dilbeck

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Springdale Arkansas

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Makes good logic, Its probably not just the one here and none there its the culmination of several things all together that make a big difference, Just balancing the fan only, probably not much difference, but in addition to the fan the head and the clutch and the blades/fly bar/shaft/and anything else that spins when added up make the big differance RIGHT?

Clint

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03-04-2008 07:24 AM  10 years agoPost 8
bellecrank

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Canada

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What many do not take into account here, is the moment arm any such runout has to work through.

In a clutch/fan system that is mounted directly onto the crankshaft of an engine, directly up against the front bearing of the engine (as seen in two stage drive systems), any runout will have far less effect then on systems that have the clutch and fan mounted on a seperate hub, that has them situated a fair distance away from the front bearing of the engine.

This distance act as a moment arm, through which the imbalance forces, that result from runout, can be greatly amplified. Consequently they are of much greater significance.

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03-04-2008 08:14 AM  10 years agoPost 9
ez2bgman

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N'awlins, LA

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Its probably not just the one here and none there its the culmination of several things all together that make a big difference
Not really true. When I built my Xtreme 50 a couple of weeks ago, I used a friends dial indicator to dial in my fan hub/clutch (which uses the collet system to center the fan hub). Unfortunately I misread it. I had a severe high speed vibration when I fired her up for the first time. We pulled the glow plug and turned the starter shaft by hand. You could definitely see a noticeable wobble in the fan hub. I went and purchased my own dial indicator and redid the fan hub/clutch. I was able to get everything under .002". It was immediately noticeable on the bench. When I fired her up this time, the engine was running very smooth and you could not see any vibration anywhere in the heli.

I think that fans that use a collet system to center them on the crankshaft can benefit from dial indicating. All my 90's have used the collet system and I always dial indicated them. With a screw on fan, there really isn't any adjustment that can be made to ensure that the run out is true. But with the collet system, you can turn the fan a little at a time until you get it within acceptable limits.

Gary
Hot Girlz in da gallery

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03-04-2008 11:48 AM  10 years agoPost 10
Dilbeck

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Springdale Arkansas

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So i guess with my hawk with a screw on fan there is no adjustment?

Clint

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03-04-2008 12:37 PM  10 years agoPost 11
jester4

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Brampton, Ontario

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There is no runout adjustment on a screw-on clutch/fan system. I'm not even certain that balancing the clutchbell or fan on these type of systems can be of benefit.

My predator gets the dial indicator/balancing treatment. My Hawk is build and fly.

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