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< might have had an engine
failure at 50'
I don't know what to say
Rich. You're convinced a filter with 10 times the surface area is more
likely to fail? All of the evidence says the complete opposite. Why don't you
come up with a real world test to prove your point?
You could put your two methods side by
side, then start adding debris.
-al
----- Original Message -----
Sent: Tuesday, August 07, 2012 11:09
AM
Subject: [FlyRotary] Re: Fuel Filters.
Was: Rotary Forced Landing
Of course, Al,
I am missing the part where the hopped up autophile jumps on the highway
with his souped up car, steps on the small pedal and cruises at 75%power, with
no letup for say-- 4 hours, to be followed by a similar situation over and
over again.
The flow for a 600HP engine would be considered, only if it were run
under the above circumstances.
Most cars, unless long distance racers, many of which don't finish (and
one wonders if they, indeed use these types of filters,) independent of their
increased HP function at much much reduced HP and fuel burn most of their
lives (thus the old saw about not using an automotive engine for an airplane).
Aircraft engines, or engines used on aircraft have different thirst needs.
Not, IMNSHO noise, but possible reality.
Of course the vehicles with the fuel filters "totally unnecessary to remove" are not designed to have
the longevity nor the fuel burn of our aircraft.
Assume the life of an aircraft to be
20 years (although they are considerably longer)
Consider an average fuel burn of
10GPH
Consider flying 100H per
year
Consider average auto at 20
MPG
The aircraft at 20 years will have
consumed 20,000 gal of the smelly stuff.
A similar flow in the auto would
equate to 400,000 miles.
Where the aircraft is still
relatively "new" it is only very rarely that an auto makes that kind of
mileage and is typically shredded long before that. Is it possible that these
self-crap-shedding filters have, for aviation purposes, a limited life span,
which, since blind, can not be evaluated, except at failure?
The benefit of being able to look at
a filter element is the ability to take some recourse if problems pop up.
Inability to inspect stops one from not knowing (although, for some, there is
solace in that). "If I can't see it, it must not be there."
What comes to mind is the situation
with Chris Barber in which, for whatever reason chunks (sheets) of epoxy-stuff
were flaking into his fuel tanks. I don't know how Chris determined this, but
lets, for the sake of conversation, this situation was not observable through
the filler neck (perhaps happening in a baffled area removed-- there are at
least 1 or 2, can't remember, however, the fuel pickup is visually isolated
from the filler neck area, and the flakes plugged the filter due to their
shape and size, he, after solving his cooling problems might have had an
engine failure at 50' on landing after a 5 hr cross country. Of course, when
he arrived back to Terra Firma, short of the runway, hopefully in one piece,
the un -seeable filter would have "cleaned" itself, and the engine failure
would have been, probably, relegated to something else.
Rich
In a message dated 8/7/2012 10:24:47 A.M. Central Daylight Time,
alwick@juno.com writes:
<not taken into account is that the fuel flow of an aircraft is
significantly greater than that of a car
Not true in this modern age. 30
years ago would have been true.
They do take high
flow into consideration. They design the systems to handle the
extremes. When we do qualification testing we measure how close we are to
failure threshold. "Holy crap, if this guy has partially clogged filter
similar to ones we find on Kentucky cars 15 years old. AND he is running at
full throttle. AND he has replaced injectors with high flow
ones..........no, he's still within the safety margin."
Have to admit, I don't know the
details of Mazda fuel flow thresholds. But I do know Japanese
companies are expert at design optimization. They do measure how well
sys will perform in unusual applications. We have what's called a
"noise array" and test how well sys handles unusual situations outside of
our control. So high flow injectors would be in the noise array. As would
fuel from "Bob's rusty tank".
Would flow for 600 hp engine be
considered? No, not that extreme.
<filter/pump were removed inspected and cleaned, I personally would
feel much better about that installation.
Yes, I think a lot of people are
not used to the concept of a design so robust that failures can't occur. In
the case of OEM fuel filtering, it's totally unnecessary to remove and
inspect. If curious, use one of those scopes to peer into tank. In this
case, remove and inspect would increase risk. I love the irony.
-al
-al
----- Original Message -----
Sent: Tuesday, August 07, 2012 7:39
AM
Subject: [FlyRotary] Re: Fuel
Filters. Was: Rotary Forced Landing
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
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N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
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