Hi Ron,
> I have a 914, not flying yet. I purchased a tool from the guy who makes
> the lead scrubber additive (not TCP, the one not for use with certified
> aeroplanes, but you can transport in cabin)
Decalin?
> that measures at what
> altitude you can fly to with the brew in your fuel tank. It takes into
> consideration temp, % of avgas, % of mogas and % of alcohol. It's a
> syringe that you pull a specific vacuum on a scale,
Hey, great idea!
An easy way to do this is to measure the pressure drop inside the
suction line (fuel pump inlet, downstream fuel filters) (you have to
measure this only once, preferably on fuel filters at the end of their
life) and pull this amount of vacuum on your fuel sample and see if it
starts to "boil" in that condition. If you take a sample of the fuel in
the tank, you already have the correct temperature and %avgas and
altitude applying to your situation.
I could even make a built in device that does so automatically and
registers whether bubbles develop, and gives an alarm.
Or, even much more simple: install a piece of glas in the fuel line (the
standard Europa fuel filter with its internals removed will do) and
detect if any bubbles are passing. It could give an instant alarm when
bubbles are detected "Vapor lock! Vapor lock!". Just as with boiling
water, micro bubbles will start forming some time before hell turns loose.
Regardless of changing circumstances (altitude, throttle setting, fuel
temperature) it would instantly alert for dangerous conditions.
> That said, do you have a differential pressure gauge on your 914?
Yep. I'm one of the guys stressing the importance of such a gauge.
> Do you
> have a single point of failure or restriction in your system like a
> gasculator?
No, I have two filters, each connected to one fuel pump.
> What happened when you turned on pump two,
> did it not make a change?
I had already two pumps on when it happened, but I think that one pump
had performed better in this situation due to the lower pressure drop
over the fuel filter.
> I don't know if your mogas has alcohol in it, but flying up high and
> into colder conditions can make the alcohol that has commingled with
> water to precipitate out and cause problems.
I only buy fresh mogas and pour it in just before flight.
> I will make sure when I do the required by Rotax (but not many folks
> do this great test) CO test to make sure your leanest cylinder is
> running rich enough at War Emergency power (I will also test between 85
> and 100% too),
I plan on installing an injection system this winter, to get rid of the
carbs, and getting the correct mixture in all cylinders all the time.
Frans
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