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Date: Wed, 16 Feb 2005 12:17:33 -0600
From: Jim Sower <canarder@frontiernet.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Bad day at the airport
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Thanks Tracy. 
I'm not trying to cause a panic or anything.  I believe that volatility 
has to be high on any list of potential problems and is aggravated by 
the fact that it varies a lot and we don't have the information at our 
fingertips.  If we're using Mogas, we need to be aware of the Reid Vapor 
Pressure of what's being sold where we live and have some notion of 
seasonal changes.

I never thought alcohol could hurt metal airplanes, but I'm firmly 
committed to the composite community and it can be devastating to the 
Cozy / Velocity population.  There are viable coatings available, but 
they don't lend themselves to retrofitting.  Again, we have to be aware 
of the issue so as to avail ourselves of the workarounds that do exist.

Trying to get my system configured (with uncoated tanks) ... Jim S.

Tracy Crook wrote:

> I agree with everything Jim is saying about alcohol, auto fuel & vapor 
> pressure. 
>  
> But I want to stress that there is absolutely no reason you should 
> have to worry about these things if your fuel system follows a few 
> simple guidelines.  The first of which is KEEP IT SIMPLE!   A car's 
> fuel system is pretty simple and there are millions of them operating 
> with no vapor lock problems, including people who drive at high 
> altitudes.     None of the people driving cars ever even thinks about 
> whether there is alcohol in the fuel or not.  I don't either, even in 
> my airplane.
>  
> The issue of composite compatibility with alcohol is a separate 
> question.  After experiencing problems with a couple of aircraft fuel 
> tank sloshing compounds, I distrust all of them.  The only fuel 
> sealing agent I trust are the polysulfide compounds.  ProSeal is one 
> brand of polysulfide sealant but there are others.  It is impervious 
> to anything you might find in any fuel, including the stuff formed 
> when alcohol is mixed with water.
>  
> Tracy
>
>     ----- Original Message -----
>     *From:* Jim Sower <mailto:canarder@frontiernet.net>
>     *To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
>     *Sent:* Wednesday, February 16, 2005 1:33 AM
>     *Subject:* [FlyRotary] Re: Bad day at the airport
>
>     Paul wrote:
>
>>     Hi, Jim....yes, I use the same gasoline as I use in my car.
>>     (Regular unleaded).  I think Tracy and Ed Anderson also use it,
>>     as they mentioned that their spark plug life is greatly
>>     deteriorated when they are forced to use 100LL.  Guys, please
>>     step in here and correct me if I am wrong.
>
>     Right so far.  Unleaded is MUCH better for your engine than Avgas.
>
>>           Regarding alcohol, I am not overly concerned with it. I
>>     coated my fuel tanks with 3 coats of the fuel tank sealant that
>>     comes with the kit. (Smells like dead fish). It is supposed to be
>>     imperviant to auto fuel and alcohol.
>
>     Alcohol is not bad for composites.  Water is not bad for
>     composites.  Alcohol and water mixed is VERY corrosive to
>     composites.  If you have alcohol, you WILL end up with some
>     alcohol / water mixed.  The stuff you used on your tanks might be
>     OK if it doesn't leak AT ALL, but how do you find that out?  Your
>     "bad day" keeps sounding like vapor lock, and some Autogas is much
>     more volatile (read prone to vapor lock) than Avgas.  You need to
>     check a bunch of suppliers around and determine the vapor pressure
>     of the gas they're delivering to their clients.  You want the
>     lowest number you can get.  Avgas has a VP of 6.0 or so.  Some
>     unleaded is down around 7.  Some more could be over 10.  That's
>     where you get into cavitation / vapor lock / etc. problems. 
>
>     Alcohol might very well not be a factor where you live, but in any
>     event it's very easy to detect. 
>
>>
>>>>      
>>>>