A thing I haven't thought about is the fuel system. The AeroVee use max about 20 L/h of fuel. The fuel lines are dimensioned for this. The UL350 draw at max more than 120 L/h, where 100 of those are fed back to the tank. The gascolator also house the draining. The old system looks like this:
This will not work on the UL350. I have finished the tank, plugged and secured all holes, oops fitting etc. I will not take all that apart again due to the risk of leakage (except oops fittings). The simplest way to fix this, I think, is a header tank.
Reading a bit about fuel systems for high pressure fuel injected engines, this is a common thing in the auto/racing industry. In racing they don't call it header tank, but swirl tank or surge tank, sometimes also catch tank. From what I gather, it is pretty much a necessity for fuel injected engines doing racing. There are tons of these surge tanks available, several different shapes and sizes. ULPower has a header tank, and this tank looks exactly like a surge tank. The basic principles for the surge tank can be found here.
So for the new fuel system, I need a header tank and a new shut off valve. The existing shut off valve will simply be a service valve for future changes.
Reading a bit about fuel systems for high pressure fuel injected engines, this is a common thing in the auto/racing industry. In racing they don't call it header tank, but swirl tank or surge tank, sometimes also catch tank. From what I gather, it is pretty much a necessity for fuel injected engines doing racing. There are tons of these surge tanks available, several different shapes and sizes. ULPower has a header tank, and this tank looks exactly like a surge tank. The basic principles for the surge tank can be found here.
So for the new fuel system, I need a header tank and a new shut off valve. The existing shut off valve will simply be a service valve for future changes.
The surge tank can also be fitted with a flop tube for negative G, but that will be for later, if ever. The surge tank is actually a very clever device. Normally it is completely filled with fuel. If negative G is encountered, it will therefore still deliver clean fuel to the pumps. The reason is that for a pocket of air to occur, the air has to first get in there. That has to be through the vent line or main inlet line, and they are full of fuel. It will take more than a few seconds of negative G before the pumps start sucking air. If air comes into the surge tank while maneuvering, that air will be vented through the main inlet and vent line. In a way, it is kind of a big gascolator with a vent line more than it is a header tank.
For better negative G handling, I think the next drawing probably is a bit better. But, if it is a good idea to have a fuel system that is capable of longer runs (minutes) with negative G when the engine itself cannot handle it, is another question. Maybe I will install an oil accumulator later, if possible on the UL350.
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