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[63.208.148.254]) by mx.google.com with ESMTPS id iq1sm8104991pbc.37.2012.08.07.12.07.27 (version=SSLv3 cipher=OTHER); Tue, 07 Aug 2012 12:07:30 -0700 (PDT) Message-ID: <5021676D.8010601@medialantern.com> Date: Tue, 07 Aug 2012 15:07:25 -0400 From: Chad Robinson User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:14.0) Gecko/20120713 Thunderbird/14.0 MIME-Version: 1.0 To: Rotary motors in aircraft CC: Saro Marcarian Subject: Re: [FlyRotary] Re: Fuel Filters. Was: Rotary Forced Landing References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------070106040509090306060105" X-Gm-Message-State: ALoCoQlmt2ReUSVQtdwXBC2nqbEnsHVOUHhBa6Lsy1y5flvJByRLqDGKbRa8vcBSFFvQLMV4HXEy This is a multi-part message in MIME format. --------------070106040509090306060105 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit The 1994 FSM wiring diagram for the rotary's fuel pump (automotive) describes two relays connected in series. The first turns _on_ the fuel pump, and the second has a resistor in parallel to it (see page 248). This is labeled "Fuel Pump Relay (SPEED)". Page 297 calls for this resistor to measure 0.57 - 0.70 ohms at 68degF. The idea is the ECU leave this relay de-energized during low speeds and loads, which adds resistance to the circuit, drops the voltage seen by the pump, and thus causes the fuel pump to run more slowly. At higher speeds it energizes the relay, shorts the resistor, and thus gives the fuel pump full power. None of this is really applicable to aircraft use, but it does show that even in 1993, automotive designers were concerned with long-term fuel pump life. As Al Wick always points out, fewer warranty service calls drives profitability and repeat sales, and they're good motivators for engineers focused on reliability in companies that sell millions of units a year of a product. So it wouldn't be fair to say that driving the pump full-bore all the time is a "common setup anymore." At least for Mazda, it wasn't even their practice 20 years ago. In an aircraft, though, this speed-control relay, resistor, connector, and associated wiring adds weight, cost, complexity and potential failure points for a homebuilder doing their own installation. I think it's reasonable and probably wise to remove/skip it during installation, and I've never heard of anybody actually using one. Our requirements are different. On 8/7/12 2:25 PM, Saro Marcarian wrote: > Ok. I can't speak to all automotive FI systems, but at least some > have full recirculating flow ALL THE TIME. Here's the scenario as I > understand it in many setups: > > Tank -> Pump (in tank) -> High Pressure Filter -> High Pressure Fuel > Rail / injectors -> pressure regulator (referenced to intake manifold) > -> low pressure return to tank > > Ingition switch on means fuel fuel pump on. The pump is always > pumping the max the engine will ever need - surely with some surplus > pressure and volume. The regulator spews back what in an automobile > will usually be a gross excess of fuel. > > Regardless of the power requirement of the right foot, the fuel pump > never knows the difference. It's always pumping it's max. I've > gotten kinda fed up with the automotive industry and don't know if > this (or a slight variation) is the common setup anymore. For > example, I've seen some cars where the pump comes on for a few seconds > and if the engine doesn't fire, shuts down. But you get the general idea. > > Al's revelations of the sloshing self-cleaning action are pretty > awesome and telling. Good thing to know. > > -Saro > > ------------------------------------------------------------------------ > *From:* "ARGOLDMAN@aol.com" > *To:* Rotary motors in aircraft > *Sent:* Tuesday, August 7, 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: > > 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. > 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 ----- > *From:* ARGOLDMAN@aol.com > *To:* Rotary motors in aircraft > > *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: > 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. > clogging/saturation? Just by making it so dang 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 ----- > *From:* Dave > *To:* Rotary motors in aircraft > > *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: >> > > 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 ----- >> *From:* David Leonard >> *To:* Rotary motors in aircraft >> >> *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 >> > > 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 >> > > 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. >> >> Tracy >> >> Sent from my iPad >> >> On Aug 5, 2012, at 10:18 AM, David >> Leonard > > wrote: >> >>> 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.net >>> >>> http://RotaryRoster.net >>> >>> >>> On Sun, Aug 5, 2012 at 6:34 AM, Tracy >>> >> > 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 >>> >>> On Aug 4, 2012, at 3:53 PM, "Al >>> Wick" >> > wrote: >>> >>>> 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 ----- >>>> *From:* Jeff Whaley >>>> >>>> *To:* Rotary motors in aircraft >>>> >>>> >>>> *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) >>>> From: David Leonard >>>> >>> > >>>> Subject: Re: [FlyRotary] Fw: >>>> Fw: [FlyRotary] Rotary Forced >>>> Landing >>>> Date: Fri, 3 Aug 2012 06:18:47 >>>> -0700 >>>> To: Rotary motors in aircraft >>>> >>> > >>>> >>>> >>>> http://lancaironline.net:81/Lists/flyrotary/Message/58662-H.txt >>>> >>>> http://lancaironline.net:81/Lists/flyrotary/Message/58662-P.txt >>>> >>>> >>>> >>>> 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 >>>> >>>> This message, and the documents >>>> attached hereto, is intended >>>> only for the addressee and may >>>> contain privileged or >>>> confidential information. Any >>>> unauthorized disclosure is >>>> strictly prohibited. If you >>>> have received this message in >>>> error, please notify us >>>> immediately so that we may >>>> correct our internal records. >>>> Please then delete the original >>>> message. Thank you. >>>> >>> >>> >>> >> >> >> >> -- >> David Leonard >> >> Turbo Rotary RV-6 N4VY >> http://N4VY.RotaryRoster.net >> >> http://RotaryRoster.net >> >> >> >> >> >> -- >> David Leonard >> >> Turbo Rotary RV-6 N4VY >> http://N4VY.RotaryRoster.net >> >> http://RotaryRoster.net >> > > > --------------070106040509090306060105 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit
The 1994 FSM wiring diagram for the rotary's fuel pump (automotive) describes two relays connected in series. The first turns _on_ the fuel pump, and the second has a resistor in parallel to it (see page 248). This is labeled "Fuel Pump Relay (SPEED)". Page 297 calls for this resistor to measure 0.57 - 0.70 ohms at 68degF. The idea is the ECU leave this relay de-energized during low speeds and loads, which adds resistance to the circuit, drops the voltage seen by the pump, and thus causes the fuel pump to run more slowly. At higher speeds it energizes the relay, shorts the resistor, and thus gives the fuel pump full power.

None of this is really applicable to aircraft use, but it does show that even in 1993, automotive designers were concerned with long-term fuel pump life. As Al Wick always points out, fewer warranty service calls drives profitability and repeat sales, and they're good motivators for engineers focused on reliability in companies that sell millions of units a year of a product.

So it wouldn't be fair to say that driving the pump full-bore all the time is a "common setup anymore." At least for Mazda, it wasn't even their practice 20 years ago.

In an aircraft, though, this speed-control relay, resistor, connector, and associated wiring adds weight, cost, complexity and potential failure points for a homebuilder doing their own installation. I think it's reasonable and probably wise to remove/skip it during installation, and I've never heard of anybody actually using one. Our requirements are different.

On 8/7/12 2:25 PM, Saro Marcarian wrote:
Ok.  I can't speak to all automotive FI systems, but at least some have full recirculating flow ALL THE TIME.  Here's the scenario as I understand it in many setups:

Tank -> Pump (in tank) -> High Pressure Filter -> High Pressure Fuel Rail / injectors -> pressure regulator (referenced to intake manifold) -> low pressure return to tank

Ingition switch on means fuel fuel pump on.  The pump is always pumping the max the engine will ever need - surely with some surplus pressure and volume.  The regulator spews back what in an automobile will usually be a gross excess of fuel.

Regardless of the power requirement of the right foot, the fuel pump never knows the difference.  It's always pumping it's max.  I've gotten kinda fed up with the automotive industry and don't know if this (or a slight variation) is the common setup anymore.  For example, I've seen some cars where the pump comes on for a few seconds and if the engine doesn't fire, shuts down.  But you get the general idea.

Al's revelations of the sloshing self-cleaning action are pretty awesome and telling.  Good thing to know.

-Saro

From: "ARGOLDMAN@aol.com" <ARGOLDMAN@aol.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tuesday, August 7, 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 -----
From: Dave
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.

Tracy

Sent from my iPad

On Aug 5, 2012, at 10:18 AM, David Leonard <wdleonard@gmail.com> wrote:

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.net
http://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

On Aug 4, 2012, at 3:53 PM, "Al Wick" <alwick@juno.com> wrote:

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)
 
From: David Leonard <wdleonard@gmail.com>
Subject: Re: [FlyRotary] Fw: Fw: [FlyRotary] Rotary Forced Landing
Date: Fri, 3 Aug 2012 06:18:47 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
http://lancaironline.net:81/Lists/flyrotary/Message/58662-H.txt

http://lancaironline.net:81/Lists/flyrotary/Message/58662-P.txt
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.net
http://RotaryRoster.net



--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net




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