I hope to answer some of your queries regarding your fuel situation. I refrained from answering, initially, because on a previous answer in a different thread, I was "taken to task." However, I
DO think it is important to look at various ways to solve your issue. The "age old" method of using the brass tube in the pick-up line is to prevent the clunk from being trapped in a forward position. That will work for tanks that have that disposition.
However, the tank that you (and I) have, gives you a much less chance of the clunk being trapped forward, being a rounded one (tank), hence, I would suggest you looking into using viton fuel tube on your clunk from
McMaster Carr and not using a brass tube at all. It also depends on the type of clunk that you use. I use the digitech clunk of which I will place photos below.
I fly F3S Jet Aerobatics and in our sequences, we have many up and down lines with pull or push out to horizontal flight from vertical flight. So it is important for me to be fully confident that I won't be "sucking air" with a trapped clunk. I know I will have input from some jet pilots regarding my suggestions,
BUT, how many
actually fly competition, is what should be the important question?
Now, on your fuel leaking out through the vent line..... Some say that because the fuel pump is sucking fuel, there won't be fuel leakage through the vent. That may be so, on a horizontal flight path whit the throttle up....however, on a down line, the turbine is at idle (or supposed to be) and there will be seepage when you pull out from the down line to horizontal. I judged at the 2018 Red Flag Jet Competition event and saw many jets doing just that, and I decided that I would bring over my 29 years experience of competing in a different discipline (Scale Aerobatics) and use some of what I learned. It is a simple fix and was also used by Andrew Jesky in his Leonardo. Most jet pilots run the vent line straight down the the outlet on the floor of the fuselage. I coil the vent (8mm). tubing) twice on top of the tank and that will solve your issue. I hope some will at LEAST try it before pooh Hooing it. You may be surprised!
Wayne
