Let's continue on and move to the fuel tank. Although the packaging in this kit isn't labeled (picture #1) the fuel tank that is included in the kit is Dubro fuel tank. The Dubro tanks are pretty high quality tanks, and they are what I prefer to use in all of my planes. Sig did a good job of putting together a kit with high quality accessories, but not all manufacturers do this. Normally with kits you won't have to worry about the included fuel tank because most kits don't come with a tank, but Sig did a great job by including a tank in this kit. That is one of the biggest reasons why I was so impressed with this kit, because Sig did a great job making it very complete and with good quality items in the kit. Anyway, back to fuel tanks. If you have a tank included with your kit, or you are building an ARF that comes with a tank, try and see if you can identify the maker of the tank. If you can't tell who made the tank then I would consider throwing the tank away and purchasing one yourself. A lot of times the included tanks are pretty low quality and will wind up leaking around the stopper or splitting the tank and leaking. This is something you want to avoid at all costs. Yes we did fuel proof the fuel compartment, but you still want to avoid fuel leaking if you can. Like I said, I prefer Dubro tanks because of their quality. But you can purchase whatever brand you are comfortable with. Now with that said, let's move on to the fuel tank assembly and installing it in the plane.

Picture #2 shows the contents of the fuel tank package. In picture #1 you can see that the clunk, fuel line, and brass tubing aren't seen and this is because they are inside of the tank itself. Remove all of the components and make sure you have everything that is pictured in picture #2. These fuel tanks are set up to be either a 2-line or a 3-line tank installation. Look at diagrams #3 and #4 to see the differences between a 2-line and a 3-line setup. 2-lines are normally used in installations without a cowl where you have full access to the fuel lines. To fill the tank you will remove the fuel line from the carb and connect it to you fuel pump, and also remove the vent line from the muffler and point it over the side of the plane. You'll fill the tank until you see fuel coming out of the vent line. Since the vent line inside of the tank is pointed towards the top of the tank fuel won't come out of the vent line until the tank is full. If you have an engine that is cowled in you usually won't have access to the fuel line from the tank to the carb, this is where you will use a 3-line setup. The 3rd line will usually go to a fuel dot on the outside of the cowl. Or it will be stuffed inside of the cowl and have something in it to stopper the line so fuel won't leak out of it. To fill the tank here you will connect your fuel pump to the 3rd line and removing the vent line from the muffler as before. If you can't get to the vent line because of the cowl you'll fill as you normally would, but you'll see the fuel coming out of the muffler when the tank is full. As I said earlier, since this is a trainer without a cowl on it we'll be doing a 2-line tank setup. Looking at diagram #3 you can see how a 2-line setup looks inside of the tank. The vent line enters through the stopper and then is bent up to the top of the tank. The fuel pickup line comes through the stopper and goes to the back of the tank and ends in a weighted pickup called a “clunk”. The pickup is weighted so that the fuel pickup line will always fall to the “bottom” of the tank as the plane changes attitudes (meaning upside down). I prefer to assemble the pickup line a little differently. If you follow the instructions with the tank you'll assemble the pickup line using the provided fuel tubing. This tubing is very flexible and can actually allow the clunk to fall forward to the front of the tank. This usually isn't a good thing when this happens. Once a clunk falls forward it usually doesn't fall back and gets stuck there, causing the engine to die because it can't get fuel any longer. I prefer to use a piece of stiff tubing inserted in the middle of the pickup line. This will prevent the clunk from falling to the front of the tank, but the pieces of fuel line before and after the stiff tubing will still let the clunk move around at the back of the tank like it should. One last note before we start putting the tank together. As with so many things in this hobby, getting into routines or habits will help you out down the line. When setting up a fuel tank I always set them up the same way so that I always know what tube is what. If you are looking at the stopper of the fuel tank I always make the upper right tube the fuel pickup, the upper left tube the vent tube, and in a 3-line setup I make the lower middle tube the fill line. One last thing along these lines. I use 2 different colors of fuel line. I use pink tubing for the fuel feed line, and blue tubing for the vent line. I do that so that I always know which line is which. There are times when both fuel lines are disconnected at the same time, and if you don't have a way to know which one is which it's easy to mix them up. By color coding them I always know which line goes to the muffler and which line goes to the carb. Whew, wow that was a lot of info. Let's get to putting the tank together.

Since we have decided to make this a 2-line tank setup we need to make sure that that the fuel stopper is correct for this setup. On this Dubro tank the stopper already had the 2 holes opened up on the stopper (picture #5), but not all tanks will have it this way. If you tank isn't like this you'll need to open up the holes yourself. The stopper of for the fuel tank consists of 4 parts, the plastic outer cap, a rubber stopper, a plastic inside disk, and a sheet metal screw to hold it together. If you look at picture #6 you can see the outer cap and the rubber stopper together, with the inner disk on the bench. If you don't have all 3 parts together as you measure the tubing in the next steps make sure that you take into account the thickness of all parts. Now we need to make the fuel pickup line. Use the first piece of brass tubing and insert it through the stopper assembly (picture #6). Push it through so there is enough tubing inside of the tank so you ca n put the fuel line on, and determine how much tubing you need on the outside of the stopper also and mark the tubing for cutting it off (picture #7). While they do make cutters for the brass tubing like this, there is an easy way to cut the tubing without having to buy a cutter. Look at picture #8, lay the tubing on a hard flat surface and put your hobby knife where you want to cut it. Put pressure down on the blade and slowly roll the tubing back and forth under the blade. This will cut the tubing fairly quickly and won't crush the tubing down as you cut it. After the tubing is cut go around the inside lip of the tubing with the tip of your knife to remove any burrs that might be there (picture #9). Picture #10 shows the pickup tubing back in place in the stopper assembly. Next we'll do the same with the vent tube. Here we need to take into account the amount of tubing inside of the tank. Make sure you have enough tubing to bend up to the top of the fuel tank. Once you have the tubing cut to length you'll need to bend the tubing so that it will be at the top of the fuel tank (picture #11). Use your thumb to bend the tubing and slowly bend up the tubing. Insert the stopper in the tank and check to make sure the vent line does touch the top of the tank. A little helpful hint here, put a light source behind the tank and you'll be able to see the vent tube inside of the tank better. The last thing you'll want to do is take a grinding wheel in a rotary tool and cut a bevel into the vent tube (picture #12). You want to do this so that the vent tube actually does vent. If you don't cut the tube down it's possible that the the tube could sit flat on the top of the fuel tank and cause it to block up. By cutting the bevel you make sure that the tube can vent as it's supposed to.

Once again I've ran out of picture space here. So I'm going to wrap up this post for the moment. Going to get some lunch for a bit and then I'll get back and continue the assembly of the fuel tank.

Pictures
1. Included Dubro fuel tank
2. Components of the fuel tank assembly.
3. Typical 2-line fuel tank setup
4. Typical 3-line fuel tank setup
5. Fuel tank stopper setup for a 2-line setup
6. Insert the tubing for the fuel pickup into the stopper assembly.
7. Mark the pickup tubing for cutting.
8. Cutting the brass tubing.
9. Use your knife to make sure there are no burrs in the tubing from cutting it.
10. Completed pickup tubing inserted into the stopper assembly
11. Cut and bent vent tube
12. Bevel the vent tube with a grinding wheel on a rotary tool.

Until next time

Ken