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Date: Wed, 28 Feb 2007 16:32:12 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: engine mount 4130 vs 304 SS
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Right: semi-monocoque. The 1st time I saw one in someone's hangar loft I 
thought it was an a/c seat. :-)

A 1-rotor should be light enough to do with some confidence If Rusty can 
get an engineer to give it a quick sanity check.

Charlie

wrjjrs@aol.com wrote:
> Charlie,
>  Almost always some kind of a monocoque built up structure. Also some 
> forms of aluminum have a yield strength near that of steel. More likely 
> the structure accomodates the materials shortcomings.
> Bill Jepson
>  
>  
> -----Original Message-----
> From: ceengland@bellsouth.net
> To: flyrotary@lancaironline.net
> Sent: Wed, 28 Feb 2007 11:36 AM
> Subject: [FlyRotary] Re: engine mount 4130 vs 304 SS
> 
> Russell Duffy wrote: 
>  > Greetings, 
>  > > As I ponder my choices for mounting the single rotor engine, I 
> noticed > something that surprised me. 304 stainless is cheaper than 
> 4130 steel. > One thing that's always bothered me about steel tube type 
> construction > is the concern for rusting inside the tubes, so stainless 
> is appealing. > There must be a catch here. > > Is there a good reason I 
> should use 4130 instead of 304? Either will > likely be sized much 
> larger than needed, since I don't have the means to > do any proper 
> analysis of the strength. > > Thanks, 
>  > Rusty (Autoflight drive supposed to be shipping next week) 
>  > Well, after wading through all the replies, everyone seems to be 
> ignoring the obvious answer: aluminum. :-) 
>  
> Sounds heretical, but there are AL mounts that have been flying for 
> decades on certified a/c. IIRC, some of the bed mounts for Franklins are 
> AL. 
>  
> Charlie