The header tank was constructed of 1/4" clark foam sandwiched between two layers of fiberglass cloth using Dow #401 vinal-ester resin with a MEK catalyst. The top line of the tank was derived by sitting in the pilots seat and running a line to the spinner. Anything below my line of sight was considered fuel tank. This technique significantly increased the volume of the tank from 14 gallons in the stock configuration to 25 gallons. This larger volume was dictated by the extremely long range requirement for N52BL. Leak testing found that there were many pinhole leaks on the top where it curves around to the side so the tank was sloshed with Randolh's 802. This stopped the leaks but I'm still concerned that this is not a good tank. Fuel in the cockpit is not a risk I'm interested in taking. This tank will most likely end up as a mold that I will build a new tank on.
FUEL001 Fuel System
Sheet 1 Fuel System
Sheet 2 Fuel Transfer System
Fuel Tank Testing
This is a great idea from Jerry Mahurin regarding testing fuel tanks that appeared in the KRnet
Date: Tue, 21 May 2002 22:57:35 -0400
To: "Daniel Heath" <firstname.lastname@example.org>,<email@example.com>
From: "Jerry Mahurin" <firstname.lastname@example.org>
Subject: Re: KR> wing tank
The glass tank in my Quickie never did leak and it was made with Safety Poxy.... The one in our current project is built with vinylester and I don't think it will be leaking on us. To test it, I put a 'T' joint on the outlet; put a baloon on one side and a tire valve on the other. Blew up the baloon a little one morning before I went to work. When I got home, the baloon was bigger. I figure just the SC Summer heat in the shop increased the pressure in the tank. Anyway it stayed pumped up for three days before I took the baloon off and installed the tank in the airplane. Keep on keeping on and some day you too will have your own airplane....!!
Following item from KRnet that supports the thesis that Auto Fuel is dangerous when it comes to the uncontrolled additives reacting with epoxy.
Date: Tue, 21 May 2002 20:35:28 -0400
To: "Keith S Melvill" <email@example.com>, <firstname.lastname@example.org>
Subject: Re: KR> Re:Fuel tanks
Wing tanks I have been flying my KR since 1988 with both wing tanks and header tank all made out of fiberglass and have never had any problems with leaks but i have always used 100LL. All the people that i know that have used regular pump gas in their fiberglass tanks have developed leaks. Kip
End of krnet Digest
Following article discusses Scaled Composits use of fiberglass fuel tanks from KRnet
Date: Thu, 23 May 2002 05:50:26 -0700
From: "Keith S Melvill" <email@example.com>
Subject: Fuel Tanks
Just to add to the Fiberglass fuel tank discussion. Last night I was talking to a friend that works for Burt Rutan at Scaled Composites and I brought up the topic of fiberglass fuel tanks. His first sentence was never vacuum bag a fuel tank, in his words the fuel will leak out faster than you can put it in. But that being said, Scaled has made many many airplanes all with fiberglass tanks with only a few problems. This is my friend's advice. The tank must be a glass-foam-glass sandwich construction using a closed bubble type of foam. Before you close the tank (put the top on) paint the inside completely with straight epoxy (or vinylester), he even suggested two coats of epoxy on the inside of the tank. He also warned me to be careful to fully mix my epoxy, he suggested a full two minutes of mixing before use. He even went so far as to suggest getting an egg timer to make sure that the epoxy is well mixed. Evidently any epoxy that is not completely and thoroughly mixed can be leached out of the fiberglass by the fuel and/or the additives in the fuel. He said that if a following this advice that my fuel tanks should be fine. My thought is that is Burt Rutan and Scaled Composites build fuel tanks like this, it will be good enough for my KR. Just some thoughts from the professionals, (Not me) Keith.
"Maturity consists of no longer being taken in by one's self."
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