I"m just brainstorming here, so bear with me. In a vehicle. We turn
the switch and the fuel pump dutifully starts pumping until we shut
down. What about a timer which runs a circuit of say 15 minutes and
switches to the other tank automatically. Of course you'd need sensors
to make sure the tank it is switching to has fuel prior to the switch.
This timer switch should only be armed with the manual valve in the both
setting. And you'd need a take off over ride which would run all pumps
in all tanks until you switched it off. Then the timer would take over
and dutifully switch tanks until a predetermined amount of fuel was
remaining and a warning light and buzzer would inform the pilot of low
fuel, we have idiot lights in vehicles now why not planes? And I agree
with Paul, the fuel gages must be very accurate. My 2004 GMC Sierra
Pickup, tells me all sorts of information, If any of you electrical
geniuses out there are willing to take this on, I'm willing to buy, and
test.
T.W. Tom Webber RV8A
wings in process. Fuselage Kit on the way.
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If you lock it down so it can't vibrate aluminum line is OK.
Short sections could be SS braided Teflon lined AN.
Some non Teflon AN line is fuel rated but it has a specific life
and must be changed out every five years as I recall. I could be
way wrong on this.
Paul Lamar ...No rotor no motor.
Tom and Paul,
I've never heard of the 5 year admonition on Teflon lined lines Paul. I
might be more inclined to believe it on buna or viton lines used with
fuel as they do get more brittle with age.
Tom on the lines aluminum is fine if you use padded clamps to minimize
vibration. I would use a short bit of flexible hose on the ends or
connections to avoid problems. FWIW the steel fuel lines used on a car
are thinner and only add a few ounces of weight. They are MUCH tougher
than aluminum lines for any questionable area. On an RV-8 there isn't a
huge amount of hose length anyway. One alternative is a newer line
available from Earls that is Teflon with a Kevlar braid. The motorcycle
racers have been using this in place of the SS braided lines. The
advantage is lighter weight and better flexibility. They are a bit more
expensive of course. One additional benefit is that they don't wear
through anything they rub against in seconds! I wanted to mention this
because it is an area that a lot of people aren't familiar with. Since
the use of ss braided lines isn't that common for most people, the
aircraft may be the first time they have used them. The braid on ss
braided lines wears through almost anything it rubs up against when
vibrating. It will wear right into your 4130 engine mount if you don't
restrain the line. Lots of racers cover the braid with heat shrink
tubing in wear areas. Using the avdel padded clamps in areas where the
lines don't need freedom to move is again a good idea. I like to allow
1/4" minimum clearance around braided lines and service loops whenever
possible. 1/2" is better, but often the clearance is limited in aircraft
use.
Bill Jepson
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I said NON Teflon lined fuel hose Bill.
Paul Lamar
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