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New fuel tanks with fiberglass innards

L'Avion

L'Avion

Well Known Member
My RV-3 fuel tanks were 28 years old and had begun to leak beyond what appeared to be fixable. Vans does not supply kits for RV-3 tanks and didn't have any ribs/baffles either, so it looked like building new plans from scratch was the only option, until I came up with the idea of no-leak fiberglass innards.

I'm posting a few pictures of the completed tanks here for starters and will scan some others of how they were assembled, to post later.

Weight resulted in exactly the same as the old tanks: 11.2 pounds each.

Barney

See Below:







 
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What about internal ribs/baffles?

You don't show any internal ribs or anti slosh baffles. It's hard to believe the weight is the same. Normally fiberglass is notably heavier than aluminum.
 
I was curious about the internal ribs and baffles, too. Also, will the new tanks have the brackets for bolting them to the spar, or didn't RV3 have those?

Roberta
 
robertahegy said:
I was curious about the internal ribs and baffles, too. Also, will the new tanks have the brackets for bolting them to the spar, or didn't RV3 have those?

Roberta
Click to expand...
Roberta, if you're talking about the "Z" brackets, none of the RVs prior to the -7, 8 & 9 had these.
 
I hope this doesn't give Van's any ideas of going to fiberglass tanks. There is already to much darn fiberglass work on these plane. Nice looking tanks tho.
 
wow, i have so many questions. i thought wing tanks were standard with the 3 now. are they not. is this because you do not have the "b" wing. ok i guess that is only 2 questions. congrads on an inventive fix
leon
 
Construction Pictures I

I have scanned these pix from 81/2x11 white paper prints, so no guarantee as to how they are going to show here, but here we go:







 
E10

beware gasohol. . . not sure if you use mogas, but many boat owners with fiberglass tanks had their engines ruined when E10 was introduced. the ethanol ate the fiberglass tanks and gummed up the engines. some fiberglass chemicals allege to be gasohol resistant.
 
Sealant?

Barney,

Pretty clever solution. I presume you're planning to seal the tanks somehow? I know a lot of Velocity builders use Jeffco to coat their tanks, and one Lancair builder I know used a brushable polysulfide sealant (like thin Proseal).
 
Questions & Answers

To answer some of the questions that have come up:

First, I am not the builder, just the "idea-man."

Baffles - "Lastafoam," 1/4" from Tacoma, WA, aircraft stock, covered w/2 plies fiberglass, impervious to fuel &/or other chemicals;

Sealing - none required, interior coated with epoxy;

and

Avgas - okay, no problem.

I have been acquainted with Robert & Valerie Harris in Covington, TN for many years. They have built, restored, and repaired countless EZ-type aircraft, built the Cozy-Jet; and operate out of the EZ-Hangar @ M04. I sought their advice in how-to and who could/would build such tanks. They pointed me to Michael Lowe who works in a hangar near theirs. Michael took my original fuel tanks and reproduced them to a "T." I asked him if he could/would do new tanks from scratch - yes.

I can field most questions about the tanks, and Michael can be reached at 731-414-4486 for serious inquiries.

For further reference:

EZJets -> http://www.ezjetinc.com/

Barney
 
...and this would solve any problem related to fuel and paint blistering around rivets as well!!!

Nice Job

Allan
 
That's a beautiful solution! Nice job! I'm continuously amazed by the ingenuity and craftsmanship I see here.

Guy
 
Any idea what was used to bond the sandwich to the aluminum? This is the area I'd be concerned about. GREAT idea, I hope it works out for you. I redid a -6 tank and hated every second of it.
 
HP gliders

osxuser said:
Any idea what was used to bond the sandwich to the aluminum? This is the area I'd be concerned about. GREAT idea, I hope it works out for you. I redid a -6 tank and hated every second of it.
Click to expand...

The Schreder homebuilt HP gliders (RS-15, HP-16 and HP-18) of the mid-70's used a similar construction... aluminum spar, foam/glass ribs and a bonded on aluminum skin.

They used Hysol EA 9410 structural adhesive... I think they sealed bays for water ballast, but didn't have any fuel to worry about...:)

gil A
 
Having built a LEZ and a Cozy, including the fuel tanks, I will say this idea has merit. The ribs do act as baffles with cut outs so fuel runs freely from section to section. Perhaps the most important consideration is materials. The various parts were made with 1/4" blue foam with a couple wet lay ups of glass with safety-poxy. The inside corner joints were taped and sealed with liberal amounts of flox. The top went on last, with flox on the ribs.

The Cozy plan is still being sold by ACS and I'm sure materials can easily be identified with ACS and tips on tank construction can be had from any Cozy or EZ builder. I no longer have the plans as they went with the airplanes.
 
Aluminum skins...

David-aviator said:
Having built a LEZ and a Cozy, including the fuel tanks, I will say this idea has merit. The ribs do act as baffles with cut outs so fuel runs freely from section to section. Perhaps the most important consideration is materials. The various parts were made with 1/4" blue foam with a couple wet lay ups of glass with safety-poxy. The inside corner joints were taped and sealed with liberal amounts of flox. The top went on last, with flox on the ribs.

The Cozy plan is still being sold by ACS and I'm sure materials can easily be identified with ACS and tips on tank construction can be had from any Cozy or EZ builder. I no longer have the plans as they went with the airplanes.
Click to expand...

David... the Safety-Poxy is good for all composite construction, but can it handle the foam to aluminum skin joints?
Bonding structurally to aluminum can be tricky.

That seems to be the unique thing about this tank... really neat...:)

gil A
 
I agree with those who are expressing reservations about the integrity of the bond between epoxy and aluminium. Aluminium oxidises within seconds and it is notoriously difficult to get a good epoxy bond to it.

I think there must be a fairly good chance that this tank might eventually develop serious leaks. I'd also be concerned that small areas of epoxy might delaminate off the aluminium sheet and block up the fuel supply system.

We need a progress report in 1000 hours.:)
 
Captain Avgas said:
I think there must be a fairly good chance that this tank might eventually develop serious leaks. I'd also be concerned that small areas of epoxy might delaminate off the aluminium sheet and block up the fuel supply system.

We need a progress report in 1000 hours.:)
Click to expand...

I'm not sure where you're seeing the problem here...

It appears that the tanks are made completely of fiberglass, with aluminum wrapped and bonded to the outside. Even if the fiberglass to aluminum joint fails, the fiberglass tanks should maintain their integrity.

The aluminum skin is attached to the spar in the same manner as a stock wing, and is in effect a wide aluminum strap holding the tank on the wing.
 
flyeyes said:
I'm not sure where you're seeing the problem here...

It appears that the tanks are made completely of fiberglass, with aluminum wrapped and bonded to the outside. Even if the fiberglass to aluminum joint fails, the fiberglass tanks should maintain their integrity.

The aluminum skin is attached to the spar in the same manner as a stock wing, and is in effect a wide aluminum strap holding the tank on the wing.
Click to expand...

I'm looking at a photo of the set-up in Post #9 which seems to show that the composite ribs are bonded to the aluminium skin. In other words the aluminium leading edge is an integral part of the tank. Am I having some sort of optical illusion?
 
Captain Avgas said:
I'm looking at a photo of the set-up in Post #9 which seems to show that the composite ribs are bonded to the aluminium skin. In other words the aluminium leading edge is an integral part of the tank. Am I having some sort of optical illusion?
Click to expand...

Yes you are. Photo #4 in post #9 definitely shows the inner fiberglass skin. The aluminum skin wraps the fiberglass skin.
 
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