Cori Hayth wrote:
> While in phase 1 flight testing I ran the main tank dry to see what it's
> like to switch the fuel selector to reserve and restart. While running
> just 1 pump it sure seemed like a long time to restart, and that was at
> 3,000' over the airport!
I did some tests too, but without flying. I found, to my astonishment,
that selecting the reserve tank by itself doesn't solve the problem. If
I don't turn the secondary fuel pump on at the same time, the fuel
pressure won't come up, probably because the primary pump sucked air in,
and with the low fuel level, the fuel will not by itself flow to the pump.
So, I tested what happens when you run the main tank dry with both fuel
pumps on. As you can guess, both fuel pumps swallow air, and after
switching to reserve, it takes a very very long time before they develop
fuel pressure again.
So, better not to forget to switch off the secondary fuel pump when not
needed.
Oh, and the order is also important: first select the reserve tank, and
only then switch on the second fuel pump!
--
Frans Veldman
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