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I have seen installations in pictures that have the pumps mounted on the firewall covered with a stainless steel shroud. It might have been yours Ed. The pumps along with the filters and Press. regulator being forward of the firewall makes perfect sense. The fuel in the cockpit area would only be under ambient press, though the return would have a slight positive pressure after the regulator.
Early on I was influenced by Bernie Kerr and Todd Bartram, in that they added extra fuel tanks in the outboard leading edge. I did the same, but followed Bernie's rout and closed in the last 3 bays of the leading edge making tanks that held an extra 14 gallons, (64 gallon total capacity) not that I want to go far but I didn't want to go
some place and have to stop on the way back to get fuel. Bernie had his tanks gravity feed into the adjacent main tank. I took a different rout in that the fuel line exits out the back of a cover plate on the spar and travels down the back side of the spar into the cabin. The lines then penetrate the center spar section through one of the predrilled holes. Needless to say Van's doesn't approve of this alteration.
Bob Perkinson RV-9 13B
From: Ed Anderson <eanderson@carolina.rr.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Fri, February 25, 2011 10:18:20 PM
Subject: [FlyRotary] Re: Fwd: Fuel injector pump cooling??
So far I have around 560 hours on my two tanks with a
single selector switch and a facet pump between tanks and my hi pressure
section. I got around any return to tank problem by returning all fuel to
a very small header tank holding around 1/2-3/4 pint of fuel located on the
bottom of my firewall. In effect it's almost a 'returnless' system similar
to that found on many modern automobile fuel set ups.
I do have the header tank and Hi pressure pumps located in
a fiberglass box covered with stick back aluminum tape (for radiant heat
reflection) and an blast tube funneling cooling air into the box. Its
worked fine for over 10 years.
All Hi pressure fuel elements are forward of the stainless
steel firewall in the engine compartment - none in the cockpit area (my
preference).
With my EFISM set to remind me of fuel transfer at what
ever gallon amount I want (I usually have it set at four gallons which seems to
provide a good set point for balance in my Rv-6A). The alarm flashes and
will not stop until I take overt action to switch tank and punch off the
alarm. Not perfect, but simply, few parts and no way to pump fuel out of a
tank overboard.
While that is my preference, so long as it a system is
fundamentally safe and provides adequate indication of fuel status and fuel
system condition, any number of designs can/will work - its all in what
makes you feel comfortable.
FWIW
Ed
Sent: Friday, February 25, 2011 6:00 PM
Subject: [FlyRotary] Re: Fwd: Fuel injector pump
cooling??
Thanks, Bill. Your points are why I haven't given that setup
serious consideration. And while $500 (for the Andair) is cheaper than a crash,
it isn't cheap enough to sound reasonable as a solution. :-) With an
inexpensive pump having anti-siphon features, it's making me consider yet
another option: a transfer pump for each tank, with no selector valve at
all. Of course, that means more (or at least different) complexity, and more
weight. The L/R imbalance issue is about the same for an RV.
Without decisions, I'd have hundreds of hours flying by
now.... Charlie On 2/25/2011 5:40 AM, Bill Schertz wrote:
Charlie,
I would caution about your using a selector ‘normally’ and returning to
only one tank. I believe that it puts too much workload on the pilot,
especially when you don’t have max fuel. I don’t know about RV’s, but my
experimental (KIS) shows a definite development of the tendency to turn
towards the heavy tank when they get very far out of balance due to uneven
fuel content. At about 5 gallons difference in the tanks, I start to have to
apply steady pressure to the ailerons to correct it. So, if you are getting
low down to half tanks, and start drawing from the non-return tank, it might
not take very long to deplete that tank with the excess fuel being dumped into
the return tank. Our pumps move the fuel rather fast, faster (I believe) than
the certified planes that use that system. A prototype Pulsar with the
system as you described had this problem during an early test flight when he
started with ~10 gallons in each tank, switched to the non-return tank, and
ran out of gas much faster than expected, couldn’t get the pump to prime in
time from the other tank, and had an off field landing.
Andair makes a nice duplex valve that returns the fuel to the tank it
came from. Costs a lot less than an off field landing.
FWIW
Bill
Schertz
KIS Cruiser #4045
N343BS
Phase one testing Completed
Sent: Thursday, February 24, 2011 5:18 PM
Subject: [FlyRotary] Re: Fwd: Fuel injector pump
cooling??
Ouch;
I hadn't thought about that. But I suspect that even a low pressure pump would
damage the tank if the vent is blocked. Thanks for the data point on the fact
that a high pressure pump can be used effectively as a transfer
pump. Were you using a separate port on the main tank for your transfer
point? My tentative plan is to T into either the regulator return, or
(assuming an effective back/anti-siphon setup), into the main supply between
tank & engine pump. Obviously, the anti-siphon feature would need to be
bullet proof to tap the supply line. One option I've considered is to
use the fuel selector 'normally', but have all regulator bypass return to a
single 'main' tank. This arrangement is actually used in some certified planes
with injected Continentals, but I'm leery of having my primary engine pump run
dry for even a very short interval as I empty an aux tank. I suppose that with
that arrangement, it would only run dry for a couple of seconds ( :-> ), so
maybe it would work out fine. Any
thoughts? Charlie On 2/24/2011 2:36 PM, Steven W.
Boese wrote:
Charlie,
I initially had my
RV set up with a Facet transfer pump with an external check valve. The
check valve spring was replaced with a slightly stronger one so that it
served both the anti back flow and anti siphon functions. The high
percentage of the time that the Facet transfer pump was operating convinced
me to change to the type (not the exact part) of pump you are
considering. The pump seemed reliable but after a couple of instances
of transferring fuel out the receiving tank’s vent in spite of a timer on
the transfer pump, I eliminated the transfer function altogether. The
possibility of applying up to 90 psi to the receiving tank if its vent
malfunctioned did not suit me. It would not take anywhere near this
pressure to fail the tank. The procedure for leak testing the fuel
tanks cautions not to apply even a couple of psi to them. The
limitation here really was me, though, not the
equipment.
Steve
Boese
RV6A 1986 13B NA
RD1A EC2
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf
Of Charlie England
Sent: Thursday, February 24, 2011 12:23
PM
To: Rotary motors in aircraft
Subject: [FlyRotary]
Fwd: Fuel injector pump cooling??
Anyone see any
issues with one of the automotive in-tank pumps being used outside the tank?
Looking at the overall pump/pickup/regulator/level sensor/etc assemblies in
most auto fuel tanks, it would appear that the pump itself would be above
the level of the fuel anyway if the tank is less than 1/4 full.
I've
been looking for a Facet transfer pump that has both a backflow valve &
an anti-siphon valve (40257 is one) but they are very hard to find &
expensive when you find them. During my search, I ran across
this:
http://www.amazon.com/gp/product/B000BMBSS0/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B002YP4Q3Q&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1JFK34G48EBF5R93EB2Y
The
application appears to be 87-98 GM products.
It appears to be very
similar to the 'standard' in-line pump that Tracy supplies, with the
exception of plastic components in the output end. Assuming that it's a
positive displacement gear pump, it should supply both the backflow &
anti-siphon features I desire & at roughly $30 shipped, it's cheaper
than even the cheapest Facet 'solid state' transfer pumps. I'm hoping that
cooling/lube won't be an issue as long as it isn't run 'dry' for more than a
few seconds at the end of a transfer
cycle.
Charlie
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