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Sorry I wasn't clear. There is a direct correlation of epoxy chemical
resistance to the designed ratio for mixing. All epoxies that specify a 50/50
ratio are inferior to those that specify 80/20 for example. Likewise, all
epoxies that are post cured with heat have substantially better chemical
resistance. There are a bunch of us who have tested our epoxy to verify it's not
sensitive to fuel type. All of us have had the same results....no problem. But I
always encourage people to do the test themselves. Way better than making
speculative decisions.
Just put a chunk of each of your tank components in know alcohol fuel.
Place in mason jar, lid on. In fact, use two mason jars, one with water in it
also. Then every few months, replace the fuel with another batch. 6 years later,
you will find the same thing we did. No effect.
As someone else pointed out, I'm not saying to change the ratio. I agree,
follow the recommended ratio.
-al wick
Al,
Just so we are talking about the same thing here,
I've asked some questions in the body of your e-mail.
No, I wasn't speaking of polyester. You can buy epoxies of different
ratios. I'm told by expert (Gary Hunter) that all epoxies which use ratios
like 80/20 have significantly better mechanical and chemical properties.
Better properties to
what?
1. All epoxies uses strict ratios, as I
explained!
2. The ratios are set by the
manufacturers.
3. There are different quality Epoxy Resins - I
agree, but the quality can't be quantified by the ratio of the resin to
hardener alone, to my knowledge!
4. The dearer resins are quite obviously, better
quality!
5. The Quality resins are those most often used in
Aviation and there is comprehensive information available on structural
strength etc.
6. If someone where to use a cheap Epoxy
without researching it's properties - I would be very
concerned.
7.Are you suggesting that people may use a cheaper
(non structural) resin to line fuel tanks and my therefore see a break-down
of the material sooner?
George (down under)
This is measurable, and agrees with my and other peoples
tests. Like I say, I tested all of the fuel tank components in
various batches of alcohol fuel for years (you know how I don't like
design assumptions). None of the components were affected. The only
exception was when I exposed 50/50 epoxy mix to fuel. It slowly got mushy.
I have seen fuel tanks destroyed, leaking like a sieve from exposure to
alcohol fuel. One reportedly had old version of proseal inside. It
completely peeled off tank inside. Clogged fuel port. Forced
landing. If memory serves me correct, it also had poly that degraded by
erosion. It looked like someone had etched the poly out of the tank.
Al,
You must be speaking about Polyester as Epoxy
must absolutely maintain a strict ration mix, as per manufacturers
instructions, to allow proper molecule to molecule bonding of
the hardener and the resin. Polyester on the other hand has flexibility in
that, more hardener promotes hardening sooner.
George (down under)
I tested the hell out of that. No effect. Years of exposure to
different batches of known alcohol. I understand that if you use a resin
of high proportions of hardener to resin, it's resistant. If you use
50/50, it isn't. I had 50/50 get soft from fuel exposure.
This info consistent with all the other guys that did the same
test.
-al wick
Artificial intelligence in cockpit, Cozy IV powered
by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from
Portland, Oregon
Prop construct, Subaru install, Risk assessment,
Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
It will make it less attractive for those
with fiberglass tanks. Alcohol/gas mixes are more aggressive than
either gas or alcohol alone.
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
Sent: Tuesday, January 17, 2006
8:17 PM
Subject: [FlyRotary] Auto
fuel
By the Farm Bureau Paper it is stated
that Wisconsin has passed a law that all 87 no lead will contain 10%
alcohol and that nine other states are considering it. It
didn't mention the other no lead grades. Here in Michigan it
is under consideration at this time, and there is a good chance it
pass. Other than cutting the power some what, is going to
effect the operation of the rotary in some other way.
JohnD
-al wick
Artificial intelligence in
cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on
engine/airframe from Portland, Oregon
Prop construct, Subaru install,
Risk assessment, Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
-al wick
Artificial intelligence in
cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on
engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk
assessment, Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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