Flying Or the Lack Of It . . .

Not getting much Radio Control flying in now days.  First it is hot outside and second most of the spring was to windy for me.

Now the air plane will not cooperate.  I have some kind of fuel supply problem.  I found a bunch of holes in the fuel lines so have replaced them.  Next I bought some clips to put over the ends of the fuel lines as they slip on the fuel tank feeders.  The feeders are usually brass or aluminum tubes about an eight of an inch in diameter that go through the stopper.  The stopper is compressed by a central screw that keeps the tank from leaking.

The set up is fairly simple.  There are two lines.  One line to feed the engine carburettor and the other is a pressure input line from the muffler.  As the engine runs, the pressure tap keeps positive pressure on the fuel in the tank which enhances fuel feed.  This pressure line is also the vent line when you pump fuel into the tank, it is the over flow line. 

The over flow line is set up so that  it is at the highest vertical spot inside the tank.  One usually bends the tube to do this.  Sometimes I add a piece of fuel line to the end and it rests on the very inside top of the tank.  In this case I have done so.

The fuel feed line extends in the tank almost to the rear of the tank and has a weight on it.  The weight is called a clunck.  It clunks around in the tank and uses gravity to be always at the bottom of the tank where the fuel is.

The fuel feed lines out of the tank are supposed to be set about the height of the carburettor input nipple, if to high, the fuel will siphon out and the engine will be rich.  If to low then one has a fuel feed problem.  Some engines have no problem sucking up the fuel with the privided tank pressure but newer high performance engines do not have carburettors that have good draft characteristics.  They are large diameter carbs for increased performance.  So one scarifces the performance of the engine for fuel feed.

I have that problem.  The tank is to low.  So I have resulted in using a modified pressure system.  I put a check valve in the muffler pressure feed line.  So only pressure goes in and it builds up in the tank and pushes the fuel up to the engine.  That works but it makes the adjustment of the engine very sensitive.  So I am going through the cycle of adjusting the engine.

It ain't cooperating.  Runs well at idle.   Accelerates well in the chocks (actually a table that restrains the airplane).  Place on the runway, and start the take off and it gets about a hundred feet and the engine stops running.  My thinking is the pressure is too high and I need to crank the high speed needle in some more.

I'll get there - sooner or later.