I run my fuel line on the outside and now use one of those small plastic spring loaded clamps which remain permanently on the model. They are small enough so they almost go unnoticed and you never have to worry about looking for them as they always remain on the model. I think a lot of the heli guys use them. What I like is as soon as I land the model, I immediately reach over and clamp the line to avoid any flooding issues.

As for fuel tanks I finally installed a header tank in my model. Prior to the header tank the last part of the flight always made my engine sound rough as it started to suck in air. I had tried all the clunks ie foam, sintered etc with similar results. I tried the header tank for the first time on the weekend and I will never look back. The engine runs perfect from start to end of flight.

Below is picture of my model with external fuel line. Clamp not fitted in this picture. External fuel lines dont look too bad. I like that I can see what is happening. Being able to pinch the fuel line on a DZ while it is running helps adjustment and helps clear a flooded engine.

Dont worry about the looks. It will save you a contest one day.

Peter