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<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
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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