A couple other points [ I'm currently working through a project designin/building a 25,000lb machine from stainless] For the same strength, you'll have an increased weight [Stainless ain't light..] and there are concerns with warpage when welding. TIG would help that, but in reality.. Stainless will warp
"just 'cause it can...", Fatigue crack's would also concern me..

FWIW

Jarrett

 

----- Original Message -----

From: George Lendich <lendich@optusnet.com.au>

Date: Thursday, March 1, 2007 1:33 am

Subject: [FlyRotary] Re: engine mount 4130 vs 304 SS

> Rusty, I support Bill's comments.
> The only place I would use SS is in the foot controls, it has to
> be bigger and thicker than 4130.
> I love SS but wouldn't use it on any structural component -
> especially on an aircraft of any sort!
> George ( down under)
>  Rusty,
>  4130 is simply a better material for an engine mount. Lynn's
> comments were pretty much on point, 4130 is stronger, harder and
> much tougher. Stainless usually only is truly rust resistant if
> passivated or electropolished after welding. The welding process
> brings some of the iron to the surface and the area around the
> weld will rust in the area of discoloration. Stainless is VERY
> subject to hydrogen embrittlement too. This can cause cracking on
> welded structures used in vibrating assemblys. 4130 isn't as
> subject to H2 embrittlement. So there are lots of reasons to use
> 4130. If the structure is suitably overbuilt this might not be a
> problem, but you better be sure of that. A engine mount failure is
> a VERY BAD thing on a autogyro.
>  Bill Jepson
>
>  
>  -----Original Message-----
>  From: rijakits@cwpanama.net
>  To: flyrotary@lancaironline.net
>  Sent: Wed, 28 Feb 2007 8:35 AM
>  Subject: [FlyRotary] Re: engine mount 4130 vs 304 SS
>
>
>  Ernest,
>  
>  """> Thomas, I don't see the benefit of stainless being the
> protection of the
>  > inside of the tube......""""
>  
>  I don't like stainless at all , unless there is no workable
> alternative...
>  
>  Rusty wants the bling on the thing!!
>  
>  Thomas 
>  --
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