Today I worked over the fuel system and fuel tank. I had planned to install the turbine tonight but that will have to be tomorrow. I have many jet projects right now and had to do some building on those. So, on to tonight's project. I took the factory fuel tank out to clean the tank and change some things with the plumbing. here are some specs of the system.
Tank capacity: 101.2 oz
Stock fuel line ID: 3mm
Stock tubing through stopper ID: 3mm
Stock clunk weight: 18 grams
Stock clunk ID: 2mm
I changed the tubing and line to the following;
Fule line: 4mm
Fuel tubing through stopper: 4mm
Clunk weight: 21 grams
Clunk ID: 5mm
So here is what I did and why. The first thing you need to do to any fuel tank (ARF or not) is to clean it, to remove any molding release agent or things of that sort. To remove the tank I simply undid the Velcro straps and pulled it off the Velcro that it sits on. Next I chose to remove the factory vent because I will be installing a Jersey Modeler dry break fueling system. (
www.jerseymodeler.com) Even if you don't change the system you will find it easier to get the line off of it if it is removed. While its out I would make a small ring and epoxy it in place so that the vent doesn't simply screw through balsa into the backing plate. I think it needs a bit more structure here. The main reason is the vent is used for more than just overflow on jets and is messed with a lot considering you will probably run a wing tank or overflow tank while starting up and taxiing, or waiting for your turn at a jet rally. Next I pulled the tank fitting and cleaned the tank using kerosene. While that sat I started in on the stopper and fuel lines. Here i chose to replace all the factory lines with bigger lines. Main reason fro this is to allow higher fuel volume to the UAT and more vent action fro fueling the plane. I then changed the clunk to a slightly heavier one and one with a bigger opening. If you run a smaller line to the UAT then it calls for you can create cavitation at the fitting causing air to enter the system on the suction side. You literally can create air. This discussion could go on a thread all on its own but I will stop here with that. You may notice that I am using Zip ties for "clamps" or "safety wire". I use high quality fuel resistant T&B ties with stainless clips in them. On the fuel system it takes very little pressure to keep the line from coming off, I will put these zip ties up against any retaining system out there. Once again a whole other thread. I then reassembled the tank and reinstalled it in the airframe.
The UAT i am using will mount under the radio and valve tray and stick out into the battery tray. This will allow me to see the UAT while fueling. The instructions call for it to be mounted under the tray. I will give measurements and weights of the mount I make tomorrow.
Lets Talk about the capacity of the tank. 101.2 Oz, this is great for turbines up to about a K100 and will give you somewhere in the 7-8 min flight time. Which is great for the beginner turbine pilot! gives you plenty of time to practice approaches and such. I think 101.2 oz is a little shy for a K140, probably in the near 5 min mark for average flying. We will get actual fuel burn and fuel remaining numbers on the K100G when we do our test flights. Right now all I can do is speculate based on the numbers out there on fuel burn. So this concludes my thoughts and actions on the fuel tank. Here are some pictures of the tank and parts.
The first three pics are of the stock system. Any pic with black zip ties are of the "upgraded" system... just to clarify