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Pietenpol-List: aluminum tank

Posted: Sun Oct 03, 1999 11:26 am
by matronics
Original Posted By: Gary Leopold
We've all had a lot of good discussion about welded aluminum and fiberglass tank construction. Weight, cost, leaks, cracks, ease of construction...all great discussion and good considerations. I still feel that I want an aluminum one. I see two things that are a pretty major hurdle for me to wind up with a welded one.1. I lack the experience. (But this is nothing new...haha...part of the fun) I need to learn more about properly designing the welded seams to prevent cracking. We know that a slight joggle at the seams should prevent this. Does anyone have a good reference source that gives guidance on this? 2. I don't have the tools. Compared to the cost of fiberglass lay-up, the cost of buying or renting a TIG welder rig seems prohibitive as is hiring a professional welder.In view of hurdle #2, I have decided that I will construct both fuselage and wing tanks of aluminum with riveted seams, sealed with fuel tank sealant. Here's my logic:1. Why not....I can name lots of airplanes with wet-wing fuel cells that seem to work just fine.2. I have the experience from repairing wet-wing fuel cells.3. I have the tools to do the job. 4. I think I can afford the materials. Surely between Boeing, Learjet, Cessna, and Beech here in town....sealant materials should be available.5. I like the idea of the challenge to come up with the proper design. Still need to learn about crack considerations.6. I am confident that I can wind up with a light weight tank in the end.I think I am home free....does anyone have any other suggestions, pro's, or con's to think about? By the way, Leon....you are nearing completion of your fiberglass tank aren't you? How's the weight? Has anyone else weighed their tanks?Terry B________________________________________________________________________________

Pietenpol-List: RE: aluminum tank

Posted: Mon Oct 04, 1999 6:51 am
by matronics
Original Posted By:> BARNSTMR(at)aol.com [SMTP:BARNSTMR(at)aol.com]
Hi Terry,I may end up doing the same thing, riveting a fuel tank together. However, I willfirst try to find a good TIG professional through the Good Ol' Boy network.If you do proceed with the riveted tank, I can offer a little advice. I spentthe first 5 years of my engineering career after college working for General Dynamicson the design of the F-16, which had a "wet wing". Two different typesof rivets were used in the construction of the wing, normal "bucked" rivetsand Cherry type structural blind fasteners (not "pop" rivets). With both types,before installation of the rivet, the rivet hole was cleaned with a solventsuch as MEK to remove any trace of oil or grease. The rivet shank and head werethen coated with a wet sealant (sloshing sealer) and installed normally. If using bucked rivets, the shop formed head is then filleted and coated overwith the sealant. The outside head of either type of rivet was then coated withan epoxy primer. All seams should also receive the sloshing compound sealing.One other note - if you plan on running auto gas in your plane, be sure the sealantyou use can withstand alcohol. Most auto gas contains some alcohol thesedays, and it can play havoc with your tank if the sealant is not formulated towithstand it.> -----Original Message-----

Pietenpol-List: RE: aluminum tank

Posted: Mon Oct 04, 1999 7:07 am
by matronics
Original Posted By:> Jack Phillips (EUS) [SMTP:EUSJCPH(at)am1.ericsson.se]
What is the matter with this discussion list? It deleted about half of what Isaid! I will try again.... With both types, before installation of the rivet, the rivet hole was cleanedwith a solvent such as MEK to remove any trace of oil or grease.The rivet shank and head were then coated with a wet sealant (sloshing sealer)and installed normally. If using bucked rivets, the shop formed head is thenfilleted and coated over with the sealant. The outside head of either type ofrivet was then coated with an epoxy primer. All seams should also receive thesloshing compound sealing.One other note - if you plan on running auto gas in your plane, be sure the sealantyou use can withstand alcohol. Most auto gas contains some alcohol thesedays, and it can play havoc with your tank if the sealant is not formulated towithstand it.> -----Original Message-----