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From: Dale Rogers <dale.r@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: PSRU adapter plate
Date: Wed, 22 Jun 2005 17:52:00 -0400
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FWIW, there is very little difference in the modulus of 
elasticity of the three most commonly available AL alloys: 
2024, 6061 & 7075.  Thus, for any given thickness, they're 
all going to flex about the same amount.  Moreover, the 
fatigue endurance limit for 7075 is only 23Kpsi.  2024, if 
you can get it, is a better choice, but it will still need 
to be thicker than 1/4", so why pay the higher prices?

Dale R.


> From: "Tracy Crook" <lors01@msn.com>
> Date: 2005/06/22 Wed PM 04:43:30 EDT
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: PSRU adapter plate
> 
> The error in reasoning here (7075 is twice as strong as 6061 so it can be half as thick) is that the bending strength of a plate is far more influenced by its thickness than by material strength.   This is in addition to the fit problems pointed out by Dean.
> 
> Just not a good idea.
> 
> Tracy
> 
> 
> 
> > My bellhousing is to heavy. Dave McC is considering buying it for his 
> > Europa, so I've been researching what it would take to replace it. I 
> > think Tracy' s adapter plate is a very elegant solution for the 
> > homebuilder (ie, those of use without a foundry). 
> > 
> > His adapter plate uses 1/2" 6061. I've been considering at 7075 
> > aluminum. It has about twice the cost but also twice the yield 
> > strength. If I could use 1/4" plate instead of the 1/2", the cost would 
> > be comparable, but I would have the very large benefit of saving 
> > something on the order of 4lbs in a very weight sensitive area. I don't 
> > have the expertise to run the numbers with confidence. All I can do is 
> > a static analysis following the directions outlined on PL's website, 
> > just like I did for the engine mount. 
> > 
> > Any advise of stuff to look for that might no be so obvious and not show 
> > up in a static analysis? (the three axis and torsional forces are obvious) 
> 
>