|Custom Aluminum Header Tank:|
The header tank on a Glasair is a small (4-11 gallons) tank that comes as an additional item that the builder can install while building if he so chooses. It is not required but has many positive reasons to install.
I chose to install the header tank for several reasons:
1) I like the idea of having a "reserve" tank. If your a motorcycle rider, like me, you can appreciate this.
2) The low wing design of the Glasair requires the fuel pumps to pull a little harder to get the fuel from the tank to where they are installed when the fuel level gets low. I tested this and the vacuum reading on the pump intake does increase as the fuel in the main tank gets below 10 gallons. The vacuum does not change with the header tank selected. For this reason I plan to use the header tank to feed the pumps during take off and landing.
3) The Glasair also has a tendancy to unport the fuel pickup in the main tank when the level is low and the pilot slips the airplane for an extended period. Using the header tank during landing will also negate this issue.
Why I chose to cut my original, fiberglass, header tank apart and install an aluminum version:
During my ground testing and through the first 10 hours of flight testing, the header tank performed flawlessly with my unique fuel system design. At ten hours I had to replace the propeller due to an unfortunate incident. A couple weeks after I had removed the prop and dash for the new prop install I arrived at the hangar to perform some wiring work. When I opened the canopy I smelled the fuel. After some searching, I found that the header tank had sprung a small leak.
Instead of wiring I removed the fuel from the header tank and examined it to find where the fuel was coming through. The next weekend I spent a couple hours sanding and glassing over the area where I found the leak.
A couple weeks later I filled the header tank and continued with the wiring. About a month went by and I had been to the airport several times and the fuel smell was gone. This day was different. I smelled the fuel when I opened the hangar door. Upon investigation I found that the header tank was leaking again. This time at a different location. At this point this was all getting pretty frustrating. I reflected back to when I built the tank and went over my notes. I had indeed added the extra coating of resin as recommended by Ralph Hudson and I had made all of my milled-fiber mixes wet when applied to seal the tank edges.
I figured it was all just a fluke and I went on with the extensive preparation and repair of the leak. Can you guess what happened a month later? Yet another location was leaking. That was it. I was done. I even contemplated removing the header tank all together. My next thought was to install a small, racing style, fuel cell. It's probably what I would have ended up with if I hadn't found Boyd Welding.
I took the measurements of the inside of my existing 6.5 gallon fiberglass tank. Using these as a guide I designed a tank that would fit inside of the fiberglass tank and connect to my existing fuel system. About 2 weeks after sending the drawing I had the tank in my hands. Great service and great welding.
To install the tank I had to cut an opening in the top of the fuselage where the fuel cap was located. The design of my fuel delivery system allows me to fill this tank from the main tank. Therefore I eliminated the filler cap in the aluminum tank.
In the first photo the aluminum tank is sitting inside the cutout and I am aligning it with the existing fuel lines. The second photo is a view from the top of the fiberglass tank showing some of the sections that I removed. The third photo shows the large hole I made for accessing the ground buss at the back of the firewall. This was always a P.I.T.A. to get to. Now it's a piece of cake (with the aluminum tank removed). The fourth photo shows the vent and return line fittings with the tank installed. The fifth photo shows the fuel level sender location.
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