Hi,

This may seem like a silly question but what is the best method for refueling my 40 size trainer? I have a 46 fx on it... I bought a handcrank fuel pump from my lhs and the guy at the counter said I could just use the pressure line going to the muffler to fuel, and then recconect it back when the tank is full... well, when I tried this after about 1/4 in of fuel was in the tank fuel started coming out the carburetor of the engine (I'm guessing because of the pressure once the clunk in the tank was covered)... so I reconnected the pressure line and had to fuel the tank through the line going to my carb... this was kind of difficult because of the way my cowl is it is hard to get to that line. What is a more conveinient way to fuel.. is there a way to install a 3rd line for fueling? how would I ensure that fuel would not spill out of the fueling line when the plane is flying? Please help!

Thanks.

Try going the other way - unplug BOTH the pressure line, and the line to the carb. Hang the pressure line over the side of the plane, pointing away and down (Tuck it under the muffler normally). Put fuel in through the line that normally goes to the carb - when it starts to flow out the pressure line, tank's full.

well that's how I ended up going about it.. but on my plane its really hard to get to the fuel line going to the carb because of the cowl... I was wondering if there is any other way to install a dedicated fueling line...

Du Bro makes a quick fill valve that does just what you want. I have one on an SN-J that works OK.

Question. Do I need to hook up the pressure line from the muffler. I have a 40 trainner with a .46 OS fx and a 8oz fuel tank. And if I do would the pressure line go directly to the tank?
Thanks

You don’t have to hook the pressure line from the muffler to the tank. We flew many years with the tank simply vented to the atmosphere. If you don’t connect the line, the engine will be quite lean and you must richen the needle valve a good bit to get it running right. By connecting the pressure line to the tank, you get better fuel draw during abrupt aerobatic maneuvers. With a trainer it won’t make much difference. If you choose to do it, the pressure line from the muffler is connected directly to the tank vent.

I have to disagree with Lou. Without the pressure line a high angle of attack after takeoff will kill the engine.
A trainer can be flown without it. But most beginers have trouble keeping the thing level. When it's in a dive and
your teacher yanks back on the elevator it will die. later daveo

Some modern engines just won't run for beans without the pressure line. The needle valve holes are sized to require the pressure. When running with pressure its common to need just 1 1/2 turn open needle... without pressure the needle needs to be about 3 1/2 turns open. (if the "jet" hole is big enough for it to work)

You don't have to buy the expensive fuel valve... You cn use the old 3-line tank setup, with the 3rd line being your fill, and just have a plug for that line ( a 1/4 inch piece of hevy wire works for the plug) Some people will put a second clunk in when doing this.. that makes it easier to remove fuel from the tank.

louw is certainly right abut flying for years withour pressure lines to the tank. When control line was all the vogue centrifugal force provided the pressure via a wedge shaped tank. With all that in mind we have progressed to the point where a pressure line is essential. The three line system works well if you don't forget to plug the filler line but in most cases two lines are fine. If you have trouble disconnecting the line at the carburetor get a fuel dot and fill from outside the cowl. They work realy well but you should remember that they have fuel under pressure and will spit at you if you misuse them.

I must respond. I am currently flying two models without a pressure line connected. One is powered by an O.S.Max .10 and the other a K&B Sportsman 20. They are old models with metal tanks with a vent only and I can do all manner of aerobatics except prolonged inverted flight without a burp (they don’t have an inverted pickup). I wasn’t referring to control line when I said we flew many years without a pressure line. I was referring to early R/C (not just rudder only but reed multi-channel also) and we did a full program of aerobatics with no muffler or pressure line. I recognize the advantages of pressurizing the tank , especially with some modern engines, and use it in most instances, but depending on the engine used, it is not really essential in a trainer.

Lou, I certainly was not putting you down. I have read your post along the way and you seem to know your stuff.
However, telling a beginer in a post he dosn't need a pressure line is not the best idea. If you were standing
next to him at the field when he tried it ,that would be different. later daveo