Received-SPF: pass
 receiver=logan.com; client-ip=64.102.122.149; envelope-from=echristl@cisco.com
Message-ID: <42011642.9080007@cisco.com>
Date: Wed, 02 Feb 2005 13:04:50 -0500
From: Ernest Christley <echristl@cisco.com>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040929
MIME-Version: 1.0
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: prop loads
References: <list-655343@logan.com>
In-Reply-To: <list-655343@logan.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Joa Harrison wrote:

> Thanks for the links.  I checked them out and didn't find quite what 
> I'm after though.  I'm more interested in typical prop forces in 
> flight and what the standards for design are.  Not so much for static 
> design but more for determining fatigue limits.  I assume there's some 
> practical standards out there that are used for certified prop 
> manufacturers.
>  
> Joa
>  

I've got some information at home, but it basically boils down to design 
a propeller that can withstand the centrifugal forces, and the lateral 
forces will take care of themselves.  The theoretcal maximum thrust from 
a propeller is somewhere in the range of 4lbs/Hp.  With a tuned rotary 
that will be something on the order of  600-800lbs.  Centrifugal forces 
range in the order of tens of tons.

Other than that, you can use the station forces that Betpat will give 
you in a classic cantilever arm analysis.  Verify that the prop material 
you're looking at will give you a sufficient safety factor (I believe 4 
is used for props?), and you're on your way.