Comments interspersed this time.


On Mon, 21 Mar 2005 08:00:56 -0800
"Al Gietzen" <ALVentures@cox.net> wrote:

> Hi Al,
>
>  
>
> Could you say a few words about how you determined what the optimum flow
>
> requirements for aircraft use shoud be.  If it's in the archives, just
>
> a pointer to the message(s) would be enough
>
>  
>
> Bob W.
>
>  
>
> Trying to put me on the spot, eh:-).

I was trying NOT to, at least too much.  I appreciate the summary, and
it was very responsive.  :)


>
>  
>
> I don’t know how to respond; it would take much more time than I have right
> now.  Much of the information has been covered, but to pull it together from
> the archives would be very tough as it has been scattered through here and
> ACRE over the last 4 years.
>
>  
>
> In general, the design is driven primarily by factors outside the engine.
> The design of the cooling jacket and the engine internals is what it is;
> Mazda has done that, and we can’t change it.  All we know is we don’t want
> the coolant to boil in there, and we know that there are potential hot
> spots, particularly around the plugs that can be the limiting factor.  We
> also know that heat load is much higher on the plug side of the engine than
> on the other, which can lead to some thermal expansion issues if the
> temperature drop across the engine gets too high; how high is to high, I
> don’t know.
>

The point that concerns me the most and the question that will only be
answered with experience is how much will the higher delta T effect the
long term reliability.

>
>
> The dyno tests should me that the flow was lower than needed for 20F drop,
> but adequate to get 30F; without a thermostat.  With a thermostat (in open
> condition) the flow was considerably lower.

It looks like the main difference is that with the EWP I will need more
like a 50F temperature differential.  

>
>  
>
> Overkill? Maybe.  I did it because I could; and I wanted to maximize the
> probability of going flying and having adequate (or better) cooling.  Did I
> get it right? You design and you test.  Some of the things I can’t test
> until I fly; so it remains to be seen.  I just know from my years of
> engineering analysis in industry that it can be a very powerful tool and
> save a lot of trial and error.  
>

I'm afraid I'm doing more trial and error although I'm trying to
copycat successful systems as much as possible.  It turns out the
trials seem difficult to set up (and expensive), and the errors are
many.

>  
>
> Al
>
>

Thanks Al, and here's hoping that both of us can get some flying
experience in pretty soon.  

Bob W.



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