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Dave says:
<How does a filter "Self clean"?
I mentioned this a couple years ago. One of the guys called Bull Sh__.
Well, not really, but what he did was most impressive. He went to local wrecking
yard, bought two used coarse filters. They reside in the fuel tank. I think he
spent like $5 or so.
Then he puts it in bucket, no I think he has old aquarium. Attached a pump
to it. Then got some dirt and debris from yard and poured it on. As I recall he
could not get it to clog. But the self cleaning was obvious when he added a
little wave action and vibration to it.
If you take this a little further, you can actually measure pump flow rate
by timing how long it takes to fill jug. You can then look at jug contents so
see how fine it screens. You can add a simple altimeter and measure pressure
drop on pump inlet. Less pressure drop means that vapor lock risk is reduced.
Tons of stuff you can measure that no one knows.
I'd think you'd find it takes around 1 tsp to clog the traditional aircraft
filter...so planes crash. Yet it takes cups of dirt to clog the filter used by
every single car manufacturer. Gigantic safety improvement.
<How DO the car manufacturers overcome eventual filter
clogging/saturation? Just by making it so dang <large it never reaches that
point?
I think they discovered that the larger the surface area, the less likely
to clog. That's why they all have around 6 to 10 times more surface exposed to
wave action than the filters of yesteryear.
-al wick
----- Original Message -----
Sent: Monday, August 06, 2012 6:57
AM
Subject: [FlyRotary] Re: Fuel Filters.
Was: Rotary Forced Landing
For the ignorati among us, I must ask.
How
does a filter "Self clean"? How DO the car manufacturers overcome eventual
filter clogging/saturation? Just by making it so dang large it never reaches
that point?
Dave
On 8/6/2012 8:48 AM, Al Wick wrote:
<how small of filtration do we need?
<size of a particle that will fit through the injector nozzle
easily?
Excellent questions. You have one resource that stands WAY above
others. What do the OEM vehicles use? They know precisely what the optimum
surface area is, optimum filtration size. Too fine, it clogs needlessly. Too
coarse, you increase risk of injector clog. Too little surface area, it
won't last. They even take into consideration unusual needs, like people
that operate at super high flow rates.
A few decades ago, cars would periodically suffer clogged filters.
Never happens any more because they have new tools to optimize designs. For
example, their course filter screen has around 10 times more surface area
than any airplane filter. Self cleaning, screen size optimized. So
debris can't affect your car. It's just brilliant.
I really worry about builders copying marginal fuel designs. Unaware of
how close they are to the failure threshold. You can fly for years with
marginal design, tell everyone "works great for me". Unaware you are
promoting failure.
-al wick
----- Original Message -----
Sent: Sunday, August 05, 2012 1:35
PM
Subject: [FlyRotary] Fuel Filters.
Was: Rotary Forced Landing
So my next question is how small of filtration do we
need? ie, what is the size of a particle that will fit through the
injector nozzle easily?
I was using the Earls sintered bronze
element at 35microns, but I also could use the SS screen version at 85
mic. The Peterson in line 600 series is MUCH more expensive and
comes in 45, 60, and 100 micron SS screens.
http://www.jegs.com/p/Peterson-Fluid-Systems/Peterson-600-Series-Fuel-Filters/1528539/10002/-1
Those do have more surface area but will be a hassle for me to retrofit,
and not sure they are worth 4x the price of the earls. Lots of other
brands I have not explored yet.
I like the sintered bronze
for strength and durability. Other opinions?
Dave
Leonard
On Sun, Aug 5, 2012 at 12:42 PM, David Leonard
<wdleonard@gmail.com> wrote:
Yea, mine is an Earls cleanable high pressure with maybe
10 sq cm worth of area. Will look into the Peterson. Thanks
Tracy. Dave Leonard
On Sun, Aug 5, 2012 at 10:48 AM, Tracy <rwstracy@gmail.com> wrote:
Al probably means the filter that's on factory in-tank pumps.
OK, but very hard to implement on RV wet-wing tanks. I
used a gascolator for low side filter on my -4. Worked OK and
when it clogged, switching on the backup pump with main pump
caused the screen disk to collapse and let fuel bypass it.
which is better than no fuel at all but not an ideal solution.
On the -8 i used a cleanable Peterson filter with TONS of
filter area, works great. That was a replacement for the Summit
Racing fuel filter with a filter element disk the size of a nickel.
It clogged up in about about 5 hours of flight.
Yes, it was the high side filter. I don't have any low
side filters. Would be interested in a source for the
self-cleaning fool-proof low side filters that Al
mentions. -- David Leonard Turbo Rotary RV-6
N4VY http://N4VY.RotaryRoster.nethttp://RotaryRoster.net
On Sun, Aug 5, 2012 at 6:34 AM, Tracy <rwstracy@gmail.com> wrote:
I assume Al is referring to the pump intake side
filter. So for the record, was it the inlet
side or the high pressure side filter that clogged? ( Both
are needed ) >From the symptoms I'm guessing high side but not
sure.
BTW, nice job!
Tracy
Sent from my iPad
As long as your are rebuilding, tremendous safety
improvement by using same fuel filter method that all cars use.
No matter how much foreign material you throw at it, it
can't clog. It minimizes pressure drop, so lower risk of
vapor lock. Self cleaning filter. Self priming pumps.
-Al Wick Cozy IV powered by RDM Subaru 3.0R. Expert
at failure prevention methods, N9032U 240+ hours from Portland,
Oregon Glass panel design, Subaru install, Prop construct,
Risk assessment info: http://www.ez.org/pages/alwick/index.htm
----- Original Message -----
Sent: Saturday, August
04, 2012 1:38 PM
Subject: [FlyRotary] Re:
Rotary Forced Landing
Dave, having gone through recently what you just
experienced I would like to say GOOD JOB on getting down
safely and with such little damage. Anyway at 1500 AGL
there isn't a lot of time ... obviously you made the right
choices.
Jeff
(Rebuilding my Ride)
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Sigh..
Yup, that was me. I have been meaning
to fess up. We were at about 1500 agl when the fuses
blew on my fuel pumps. I was in a close formation of 40
aircraft at the time too. I think I got some bad MOGAS
somewhere in Iowa as I did notice my fuel return flow
creep downward but didn't think it was a big problem.
On the incident flight, a one hour formation
flight from SQI for a mass arrival at OSH, the return
fuel flow drifted down to zero. I actually though it was
a sensor problem. I didn't have the ability to give it a
lot of attention because we were in a loose formation.
Soon after we pulled it together for a tight formation
power switched off. I tried to find a road, but quickly
ran out of options and put it down in a bean field. With
the beans hitting the flaps it brought me to a stop in
about 200ft, just before I would have gone into the full
grown corn. As mentioned, wheel pants broke in half but
no other damage besides pulling bean leaves out of every
nook and cranny. The farmers were very nice, and the
stories are true... they have attractive daughters. They
were out there barefoot in their Sunday best enjoying
the excitement. Helped me clean the fuel filter and
replace the fuses. Within a couple of hours I was able
to take off from one of their driveways as they all
waived good bye (but strangely, no one took me up on my
offer for a ride).
Landed at OSH just before dark
to a reserved parking space and a very warm reception
from the formation group and friends. Great support from
everyone all around, though I am trying to avoid the
obvious new call signs they are trying to give
me.
--
David
Leonard
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-- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.nethttp://RotaryRoster.net
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David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
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