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Al,
Of course, what is not taken into account by the auto guys is that the fuel
flow of an aircraft is significantly greater than that of a car and that old
planes are still flying and don't have the opportunity to "pull over to the side
if the filter gets plugged totally or partially.
Now if, as part of a conditional inspection, the filter/pump were removed
inspected and cleaned, I personally would feel much better about that
installation.
Rich
In a message dated 8/6/2012 10:58:34 P.M. Central Daylight Time,
alwick@juno.com writes:
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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