Started November 1, 2006
Before getting started on the fuel system, I thought that I would show how to make a flare fitting on a tube. These same fittings will be used on the tubes for the brake lines as well as the fuel lines.
Aircraft flare fittings are 37 degrees. Automotive ones are 45 degrees. Make sure that you purchase the correct flaring tool (37 degree) for making up the fittings for your airplane.
Step 1. Cut the tube to the proper length using a tubing cutter.
Lightly smooth the end with some fine emory cloth. Slip on the
flare nut (AN818) and sleeve (AN819):
Step 2. Using the proper, 37 degree flare tool, flare the end of the tube:
The flared tube:
Step 3. Slide the sleeve (AN819) to the flare:
Now you are ready to go. You don't need any type of sealer, teflon tape or goop on these fittings. Just leave them dry - they are self-sealing. Don't over-tighten them. Snug them down but don't over-do it.
The Fuel System:
The basic fuel system is shown in the January 1999 Bear-Tracks newsletter. It is a very simple, yet efficient and reliable system. The basic system is gravity fed like the Cessnas and requires no fuel pumps. If you elect to go with extended range tanks, you will need a transfer pump. I have a personal limit of about 3.5 to 4 hours before I'm ready to land and stretch my legs. Since I have a Lycoming O-360, I will get about 10 gallons per hour. With 55 gallons on board I have about 5 hours fuel so a 4 hour leg gives me a reserve of about 1 hour of fuel so I have elected to not go with the extended range tanks. I save on weight and complexity that way.
The fuel lines run from the tanks in the wings, down the front and rear door flanges and all converge at the fuel selector valve located on the floor of the cockpit. From the selector valve, the line runs to the gascolator which is the low point in the fuel system. From the gascolator, the fuel line runs up to the firewall, then to the carburetor.
While constructing the fuselage, I welded in some mounting brackets for the
fuel valve and gascolator as shown here:
Now, after sandblasting and priming the fuselage the fuel system has been
fabricated and installed:
Note: this is a picture from the top, looking aft from the firewall.
Here is a picture from the bottom, looking up:
