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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-916522@logan.com>
Subject: Re: [FlyRotary] Why rubber engine mounts?
Date: Sat, 7 Jan 2006 09:40:22 -0500
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Hi Scott,

Thought I would relate my engine mount situation.  While there are rubber 
donuts between the parts of my engine and the mount, the first time I took 
the engine off, I discovered they were mostly cosmetic.  The welder decided 
to have the center of the engine side of the mount made out of hollow tube 
(for bolt to go through) and the mount side simply had a hole (slightly 
larger than the tube) to go through.  So basically once you put the two 
together (rubber donut around the tube) and put a bolt though the two (big 
washer over the hole) the center tube is in contact with the side of the 
engine mount.  So there is really no insulation between engine and engine 
mount.

I am certain I get more vibration than if I had the mount insulated with 
rubber - but have flown 300 hours like that (keep meaning to correct it but 
other things seem to come up). Certainly would not have wanted to do that 
with a Lycoming.

So while that does not answer your question - that is my experience with 
engine isolation.

Ed

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message ----- 
From: "Scott" <squiggles@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, January 07, 2006 8:46 AM
Subject: [FlyRotary] Why rubber engine mounts?


> Hello...
>
> If our engines are smooth and the entire engine is
> well balanced, why is it necessary to isolate the
> engine from the engine mount/airframe?  Why isn't it
> appropriate to simply place a square of an old auto
> tire( or some similar material ) between the two
> points where I bolt the engine to the engine mount?
>
> What are we trying to protect the engine
> mount/airframe from the engine?
>
> I reached this point as I was diligently welding
> tubing to a plate to make cups for the rubber mounts
> which I purchased from Reid tool.  After completing
> the two of the mount points I stopped and started
> questioning, is this really overly complicating the
> process, what am I really trying to protect the
> airframe from.  Of course I identified a few, prop
> strike, loss of a rotor, among other out of balance
> scenarios.  But, as those would ideally be minority do
> I need to over design for them?
>
> Any thoughts, opinions, and comments are very much
> welcomed...
>
> Thank You...
> -Scott
>
> Reference:
> https://reidecom.reidtool.com/xephr/edit/ITEM_GROUP_DETAIL?query=*CATALOG_ID=ARFF05&query=*ITEM_NO=VM-190-3&query=*GROUP_ID=73969&query=*START_WITH_ID=73969
>
>
>
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>
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