[quote:6ba7d7472f="air.guerner at orange.fr"]Frans,
Let's take this example:
You are flying at full power at 16000 feet, ISA conditions. According to the
Rotax
Manuals, the air box pressure (absolute pressure) is 1,2 bars. The fuel pressure
at the carbs must be 0.25 bars above airbox pressure, that is 1,45 bars
absolute. Ambient pressure at 16000ft is 0,53 bars, so the fuel pressure must
be 0,92 bars above ambient. The fuel pressure regulator adjusts the flow back
to the tank so that the pump is able to supply the required pressure.
[/quote:6ba7d7472f]
I don't agree with that. The fuel pump delivers 120 liters, with 15 psi or
something
like that. The fuel pressure regulator simply opens a valve when the pressure
exceeds a limit, so the excess fuel flows back to the tank.
If the engine consumes more, the pressure drops a bit, so the valve closes a
bit,
and less fuel is flowing back to the tank. Let's say that 96 liters flow back
(your example). This means that the engine is using 24 liters per hour. The
flow through the filter is 96 + 24 liters, still 120 liters per hour. The ratio
may differ, but the total remains constant.
You can also see it like this: the pressure regulator does not communicate with
the pump, so the pump does not know what is going on and always delivers 120
liters per hour, regardless whether the engine is running at full power, or not
even running at all.
Anyway, as soon as I have the installation ready I can tell you for sure, as I
have a fuel flow sensor in series with both the feed line and the return line.
I will tell you how much flows through the filter with various power settings.
Frans
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