Received-SPF: pass
 receiver=logan.com; client-ip=24.25.9.102; envelope-from=echristley@nc.rr.com
Message-ID: <42423656.1000104@nc.rr.com>
Date: Wed, 23 Mar 2005 22:39:02 -0500
From: Ernest Christley <echristley@nc.rr.com>
User-Agent: Mozilla Thunderbird 0.9 (X11/20041127)
MIME-Version: 1.0
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EWP: How much is enough
References: <list-814961@logan.com>
In-Reply-To: <list-814961@logan.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Bob White wrote:

>Hi Ernest,
>
>Problem is, what have you learned.   It might be good data, but won't give "The
>Answer".
>
>  
>

I'm looking at the cooling system having two aspects.  First is the 
average temp.  This is determined by how much fuel you're burning and 
how much cooling your accomplishing.    The second aspect is a ripple on 
the average line.  A drop of water traveling the circuit will first get 
way above the average, then drop way below.  This aspect is wholly 
controlled by the flow rate.  Higher flow equates to a smaller ripple.  
Critical measurement is the exit temp from the engine.  I think the 
consensus has been that a 200F exit temp is the maximum.  If you shrink 
the ripple (increase flow), you can live with a higher average.  With 
low flow, you have to sink the average to give the coolant some headroom.

If we can correlate a flow to a headroom that's needed, we'll have 
better numbers for laying out the rest of the system.

>The real question is what effect the various delta T's will have on engine
>life.  I have no doubt that more flow is better at keeping the engine at a more
>uniform temperature, but have no idea what that means for engine life.
>
>  
>

I doubt that I'll have a rotary that reaches the proclaimed 2000hr TBO 
that Lycs crow about.  Rebuilding the thing is just too darn cheap and 
easy.  For $1000 and a weekend you get to see the exact condition of the 
engine's internals.   I say run it hot and fast.  Then tear it down in 5yrs.


-- 
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."