fiber glass test

[efil 01 74]

hi , as i'm building my original C kit, i made a test : 

i cut some fiber glass pieces from cowl and plug them in a bowl of gasoline SP98 (unleaded with 5% max ethanol)

we'll see what happens in few days 

one question, is the cowl fiber glass exactly same as tanks?

[FredStork 453]

There is nothing saying it would be the same resin used for cowling and tanks. It could be, but could just as well be different. I think the non resistant resin get rather sticky if you apply etahnol directly on it but have not tested myself.

[EDMO 1078]

I believe WyPaul said he has had a chunk of Wel.......?    Dang, old man just had a memory block - cant remember the name of the stuff they coat motorcycle gas tanks with  -  anyway, he has had it soaking for about 3 years, with no deterioration - After I close this, I will remember what it is!

Yes,  CASWELL...

I don't know how it is in other places, but here the Missouri Farm Association (MFA) has stations around the state that sells non-alcohol gas.  There is also a site - Puregas - that will tell you what stations in your area have the good gas.

Do you know that your "Green Acres" King Oh Bummer, has authorized or mandated that our Navy has to buy bio-diesel fuel for its planes at a cost of $59 a gallon, instead of the regular cheap fuels available?  No wonder why we are not using our carrier in the Med to carry out airstrikes against ISIS towelheads! 

EDMO

Edited 15 Dec 2015 by EDMO

[marksires 484]

I'm not a fan of any of the slothing stuff, Caswell or otherwise.  It was popular for a while in the Rutan world, since the tanks are built of fiberglass and foam, and a b*tch to get sealed.  Many of the folks that did that are now having the joy and privilege of cutting the top of the tank off (which happens to be the wing strakes) to remove it all and then do the tank properly like the plans said to do.  A few crashes from engine failures after the filters all filled up with cured slothing compound that separated from the tank walls will motivate you to do that.

Mark

 

 

[Bandit 286]

My tanks rotted and I never used a drop of ethanol.

[EDMO 1078]

My tanks rotted and I never used a drop of ethanol.

Bandit,

How do you KNOW you didn't get moonshine gas?   I have heard that the only way to tell for sure is to test it - seems like some places buy a load of whatever they can get at times.

EDMO

[dholly 718]

The federal Clean Air Act establishes national fuel emission standards, but also allows states to adopt unique fuel programs to meet local air quality needs. A number of states have adopted their own clean fuel programs for part or all of the state. Most of these programs set lower gasoline volatility requirements than the federal standards, and most are effective for only part of the year, ie. winter oxygenated fuel programs are mandated in certain areas and are implemented by the states. There is a very good chance that many state and regional additive pack blends contain other oxygenates and olefins just as corrosive as ethanol, but you don't hear as much about that because it is not standard in every area.

[birddog486 21]

The Ethanol free gas(tested to be E-free) in Southern Wisconsin only took a week to cause my tank to leak and cause major damage to the Paint/finish

[1avidflyer 1983]

Wow, that had to take the smile off you face!  What kind of paint is it?  Jim Chuk

[birddog486 21]

Yeah, It was pretty bad. That's the Stewarts system. Their paint is really bullet proof, the glue and primer not so much.(against car gas)

Edited 15 Dec 2015 by birddog486

[EDMO 1078]

I had seen the crinkled primer on your bird, but what is the deal on all the green glue showing?  Is that where the primer just came loose taking the topcoat with it?  Is the glue still holding the fabric OK?

EDMO

Edited 15 Dec 2015 by EDMO

[birddog486 21]

Ed, that's where the primer unbounded from the glue because of the leaking gas. once the gas was removed, evaporated and cleaned the glue and fabric had the strength like it was new. The areas where the primer unbounded and blistered I pulled off in sheets.

[efil 01 74]

24h of immersion and nothing ... now i wait for 15 days

[EDMO 1078]

24h of immersion and nothing ... now i wait for 15 days

The problem is, that you don't know if the cowl is the same epoxy as the tanks.   I bought tanks from the guy who used to make them for Kitfox, and he did not make the cowls, as far as I know.  We know that several tanks have leaked or rotted, and even then, we don't know if all tanks were made with the same epoxy, or that the mix and application was always the same.

EDMO

Edited 15 Dec 2015 by EDMO

[Bandit 286]

My tanks rotted and I never used a drop of ethanol.

Bandit,

How do you KNOW you didn't get moonshine gas?   I have heard that the only way to tell for sure is to test it - seems like some places buy a load of whatever they can get at times.

EDMO

Ed, I guess I do not know if the local gas station lied to me. I never tested it. I just always bought fuel out of the pump that said premium gas with no ethanol.

[saskavid 47]

Remembering back to the early days of ethanol and fiberglass fuel tanks, most of the avids were poly ester resin and the kitfoxes were vinyl ester resins. The poly  tanks couldn't take any ethanol whereas the vinyl resin tanks seemed to suffer no ill effects from the alcohol laced fuel. I also remember poly tanks using ethanol that were premixing synthetic 2 stroke oil were showing no ill effects as well. The gas I use in my poly tanks is supposed to be ethanol free premium. Haven't had any problems but I never leave fuel in the tanks between flights. As well I am mixing some 2 stroke amsoil with the fuel at around 350 to 1 to keep a barrier oil film on the tanks in the event I do get some ethanol in the tanks at some point.

[efil 01 74]

24h of immersion and nothing ... now i wait for 15 days

The problem is, that you don't know if the cowl is the same epoxy as the tanks.   I bought tanks from the guy who used to make them for Kitfox, and he did not make the cowls, as far as I know.  We know that several tanks have leaked or rotted, and even then, we don't know if all tanks were made with the same epoxy, or that the mix and application was always the same.

EDMO

agree ed, i'm not certain but i can swear that tanks are same resin as cowl for the early avids

[Bandit 286]

IMO there are only 2 types of Avid tanks, the kind that does leak or the kind that will leak.

[EDMO 1078]

I still have one tank that was in my Kitfox 1, built in the 1980's and it never showed signs of a leak, but we had real-gas in Alaska.  My 4 new tanks were built by Ron's Fiberglass after he ended his contract with Kitfox about 12 years ago.

EDMO

[Fly-n-Low 181]

Remembering back to the early days of ethanol and fiberglass fuel tanks, most of the avids were poly ester resin and the kitfoxes were vinyl ester resins. The poly  tanks couldn't take any ethanol whereas the vinyl resin tanks seemed to suffer no ill effects from the alcohol laced fuel. I also remember poly tanks using ethanol that were premixing synthetic 2 stroke oil were showing no ill effects as well. The gas I use in my poly tanks is supposed to be ethanol free premium. Haven't had any problems but I never leave fuel in the tanks between flights. As well I am mixing some 2 stroke amsoil with the fuel at around 350 to 1 to keep a barrier oil film on the tanks in the event I do get some ethanol in the tanks at some point.

Yea. Most fiberglass aviation commercial parts were vinylester before epoxy came along. My buddy has a boat with a polyester tank in it, and he found some coating to coat the inside of the tanks, epoxy.

Great thread. I have been wondering about this (what my tanks are made of) and only have had non-eth gas in it because the alcohol will attack the polyester resin.

[EDMO 1078]

I started laying up fiberglass for Chrysler about 1965 - We used Ren brand epoxy, and I never questioned what kind of epoxy it was.  I then used West System epoxy for my boat, and never even thought about whether it was polyester or vinylester, and still don't know the difference or how to tell.  I have seen some small fiberglass kits at Walmart, and think they are Bondo brand, and don't have a clue to tell what they are.  All I learned in Aviation school that if something uses a catalyst, it is not epoxy (I think that is what they said, so don't quote me on that.)

Someone with some epoxy chemical knowledge could surely educate us on this.  I would hate to try to repair a cowl or wingtip and find out that the stuff I used didn't stick to the old stuff.

EDMO

Edited 15 Dec 2015 by EDMO

[marksires 484]

Ed,

Epoxy, Polyester, and VinylEster are all different kinds of Resin/Hardener systems for use with fiberglass/carbon fiber/etc.  Within those categories, there are variations in the actual product, so even within each category, different properties of strength, stiffness, chemical resistance, etc. exist.  

The reason you want to use the same 'stuff' when doing repairs is so that a chemical bond will form, similar to the bond it has when originally put together.  If you change 'stuff', then a chemical bond is generally impossible, and you will only have the mechanical bond, which is usually weaker.  A poor, but maybe useful analogy is that if you use the same 'stuff', it is like welding, using different 'stuff' is more like brazing.

I found this site that has some generalized information:

Polyester:

http://www.engineeringtoolbox.com/chemical-resistance-polyester-d_784.html

Vinyl Ester:

http://www.engineeringtoolbox.com/chemical-resistance-vinyl-ester-d_785.html

Epoxy:

http://www.engineeringtoolbox.com/chemical-resistance-epoxy-d_786.html

I don't like mogas because you never know what is in it.  Everyone worries about ethanol, but it is only one additive that can cause grief to fiberglass tanks.  They can mix anything they want in to meet the EPA, etc. requirements for their area for that week.  And sometimes I think they just mix some crap in because they have it in a tank and need to get rid of it.  I bet birddog wishes his only problem right now was changing the plugs more frequently!

I mix TCP in with my 100LL to keep the Lead problems to a minimum.  Yeah, it adds cost, but engine maintenance (or replacing fabric/paint/fiberglass tanks) is even more expensive.

 

Mark

 

 

 

[EDMO 1078]

Thanks for the info Mark - Next question:  How do you know what kind of epoxy, etc. that the tank, cowl or wingtip was made of originally?   Maybe there is no answer to that.

100LL and TCP/Decal (?) are really the safest for the tanks, but can you use that with Rotax engines - I know my Soob will run on it.  What mix do you use per gallon?

They were putting MTBE in our Alaska gas until people started to get sick around Fairbanks because they are sitting in a bowl and the air pollution got stuck there, then they stopped that additive.

EDMO

Edited 15 Dec 2015 by EDMO

[marksires 484]

If you don't have someone who knows, there is no way to tell afterwards.  Maybe if you had a lot of lab equipment you could, but probably not worth it for our planes.

No reason you can't use TCP in Rotax - I use it in my 582.  The TCP binds with the lead during combustion, converting it to something that doesn't 'stick' and flows out the exhaust more easily.  It doesn't affect Octane because combustion has to happen for it to do anything.  Or at least that is what the research I've done indicates.  I'm no chemist, and I didn't stay at a Holiday Inn Express last night either

And unless a part is structural, the mechanical bond of the various resins to each other is probably fine.  I wouldn't hesitate to use West 105 (Epoxy) to fix my Avid Cowl, which is probably Polyester.  I just did some cosmetic repairs to the nose wheel pant on my Cherokee using micro made with West 105.  I have no idea what it was made out of originally.  

If I have to remake my tank, I'll probably use AeroPoxy, it has proven to resist avgas well in the Rutan derivative world, where everything is made out of fiberglass and foam.  I'll make a plug to match the existing tank (less tank wall thickness) out of PVC foam, glass over it, then melt the foam out with avgas or something similar that won't affect the cured fiberglass.

[Fly-n-Low 181]

 

And unless a part is structural, the mechanical bond of the various resins to each other is probably fine.  I wouldn't hesitate to use West 105 (Epoxy) to fix my Avid Cowl, which is probably Polyester.  I just did some cosmetic repairs to the nose wheel pant on my Cherokee using micro made with West 105.  I have no idea what it was made out of originally.  

If I have to remake my tank, I'll probably use AeroPoxy, it has proven to resist avgas well in the Rutan derivative world, where everything is made out of fiberglass and foam.  I'll make a plug to match the existing tank (less tank wall thickness) out of PVC foam, glass over it, then melt the foam out with avgas or something similar that won't affect the cured fiberglass.

Epoxy is not polyester. Epoxy will also "stick" to polyester, but not visa versa. It, as a patch, will delaminate. For some reason no mechanical bond. Then you have SMC. Epoxy will work, but polyester will not. Sorry- tangent. SMC mostly used on jetskis and the like.

Thanks for the info Mark - Next question:  How do you know what kind of epoxy, etc. that the tank, cowl or wingtip was made of originally?   Maybe there is no answer to that.

100LL and TCP/Decal (?) are really the safest for the tanks, but can you use that with Rotax engines - I know my Soob will run on it.  What mix do you use per gallon?

They were putting MTBE in our Alaska gas until people started to get sick around Fairbanks because they are sitting in a bowl and the air pollution got stuck there, then they stopped that additive.

EDMO

Wow!!! No kidding!!! I have heard of them going to ethanol as an oxygenizer (???) instead of MTBE because of the jet skis in the lakes. All was fine until the engine went on the limiter jumping waves and spit raw fuel out.