MAAA Wingspan

22 23 So, I spent my Christmas holidays playing with some of my planes and doing somemaintenance. It was a good time to reflect on the twomain systems that control the successful outcome of flying my planes, the radio systemand the power system (excluding gliders). When you have a nitro- burning glow engine and your engine loses its fuel supply, you’ll find yourself in a dead-stick situation with a plane that wasn’t designed to be a glider, relying on stick skill to get it back. So to this end. to prevent a dead-stick landing, the first important steps are taken at the workbench while you are installing or maintaining the fuel tank and other necessary fuel-system components. Though this is an easy task for many experienced builders, newbies may find it a bit of a challenge. I hope this article will highlight some of the basics of the fuel components that feed your model’s engine and will make all that plumbing more understandable and help withmaintenance like I have learned... Here’s some of the basics I have learnt Fuel filters are worth their weight in gold! Clean fuel means no dirt or FOD in the tanks. Whenever possible, pad your fuel tank with foam rubber - it helps prevent “foaming.” The tank is connected to the engine’s carbie with flexible fuel line (plastic tubing) and a suitable (different for nitro and petrol) rubber stopper seals it. For a tank to operate properly, it must have a vent line that allows air to enter the tank as fuel is drawn out. It releases the vacuum left in the tank. Now, our airplanes don’t always fly straight and level so to allow the fuel to flow at different attitudes, the tank has a flexible internal pick-up tube. A heavy “clunk” fitting is attached to the end of the pick-up tube to always keep the end of the tube at the lowest part of the tank and if the pick-up tube wasn’t flexible, once the fuel level dropped below the pick-up tube in the stopper the supply of fuel would stop and the engine would die... resulting in, well you know. Lengths of brass tubing pass through the tank’s rubber stopper and the fuel lines that carry the fuel to the engine slip over the ends brass tubes. The rest of the fittings and accessories help the fuel systemwork properly andmake it easier tomaintain and operate. Now I have started using the little brass fuel line barbs and soldering these onto the brass tubes. This helps the tube fromnot sliding off, alternatively a little skill with some lock wire to stop them sliding off over time and wear. JOE ‘WISE’ WANGID: EDUCATIONAL RADIO AND POWER SYSTEM ADVICE Making your fuel tank easy to get tomakes maintenance of your fuel systemeasier to do. The removable fuel tank tray can also secure your battery packs. One common problem that can lead to your engine running lean (starving of fuel) is fuel foaming in the tank. Vibration in the airframe causes this and it forms tiny bubbles in the fuel. The bubbles cause fluctuating fuel flow and the air in the bubbles causes the fuel mixture to lean out. The simple solution to this is tomake sure to wrap or pad your fuel tank with soft foam rubber. Also, make sure that after time, you check the padding to see if any part of the unprotected tank is coming in contact with themodel’s insides like a former or enginemount bolt or nut. I usually use some good ol’ zippy ties hold the foampadding in place but you can also use tape. I am finding that a little regular maintenance is the key to keeping your entiremodel in top condition. One way to keep a better eye on your fuel system is tomake the tank removable in some way. you can also use zippy ties. When there is no fuel tank compartment hatch, I make a slide-in tank tray froma little lite ply and amatching set of rails inside the fuselage. This way, I can slide the tank into place and secure it with a couple of small screws. You can save more space by attaching your battery pack to the tray as well that way you can also check your battery at the same time as your maintenance. This systemworks extremely well, especially with large airplanes. To choose the correct size fuel tank for your airplane, check your kit’s directions or check the enginemanufacturer’s recommendations. You’ll want a tank that can hold enough fuel for a 15 to 20minute flight. Now, what is a 2 line setup... 2-line setup A two-line fuel system is the simplest and almost foolproof way to go and for some of my nitro planes, the best way as it is easy to take the line off the carbie to fuel up. The setup requires only two pieces of brass tube, a clunk, a rubber stopper and a short length of silicone tubing. Bend one tube 90 degrees to form the vent and insert it through the stopper. The vent lets outside air in as the fuel is drained out, and it acts as an overflow indicator when you fill the tank. The second tube is the fuel supply for the engine and the pick-up tube and clunk are attached to it. The vent line is generally attached to the pressure fitting on the engine’s muffler which helps to pressurise the tank to enhance fuel flow to the engine. MAAALogo. FEBRUARY WING SPAN