AeroElectric-List Digest Archive

Sun 09/23/07


Total Messages Posted: 5



Today's Message Index:
----------------------
 
     1. 02:23 AM - Re: Dual ignition - was EFIS as only reference???EFIS as only reference???EFIS as only reference??? (Peter Pengilly)
     2. 02:30 AM - Re: EFIS as only reference???EFIS as only reference???EFIS as only reference??? (Peter Pengilly)
     3. 05:02 AM - Dual Ignition (Richard Girard)
     4. 06:40 AM - Re: Dual ignition (Ken)
     5. 11:38 AM - Re: Dual Ignition (Peter Pengilly)
 
 
 


Message 1


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    Time: 02:23:56 AM PST US
    From: "Peter Pengilly" <peter@sportingaero.com>
    Subject: ectric-List:Dual ignition - was EFIS as only reference???EFIS
    as only reference???EFIS as only reference??? Probably because the average mag is horribly unreliable - so two completely independent ignition systems are fitted to make sure you keep cool. Now ignition systems are potentially much more reliable, however dual ignition is still seen as "aviation standard". Peter -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David M. Sent: 22 September 2007 02:50 Subject: Re: AeroElectric-List: EFIS as only reference???EFIS as only reference???EFIS as only reference??? Just curious, but why is it so important to have 2 plugs per cylinder? The Lycosaurs and etc only have 2 per cylinder because of the jug size. One plug alone in those engines is not enough to light the fuel evenly regardless of swirl pattern so that's why they went to 2 per. My wife's brand new motorcycle has 2 plugs per for the same reason: jug size. :) David M. ----- Original Message ----- From: "Ernest Christley" <echristley@nc.rr.com> Sent: Friday, September 21, 2007 5:45 PM Subject: Re: AeroElectric-List: EFIS as only reference???EFIS as only reference???EFIS as only reference??? > <echristley@nc.rr.com> > > Peter Harris wrote: >> Now that I have been through the exercise (which was a learning >> experience >> for me) I would seriously consider the EC2 which has simple pilot >> controls, >> simple programming and it has the advantage of dual redundancy, for a few >> less dollars. It was developed and marketed by a family company purpose >> built for aircraft (although not certificated.) The Megasquirt would also >> be >> OK if you want to save dollars and it could be made dual redundant. >> >> > > Peter, I'm going through this exercise now, and I've settled on the > Megasquirt. The only thing that recommends it for me above the EC2 is > that I get to play with the source code. Not helpful unless you're a > software engineer. > > The way I'm handling redundancy is that the Megasquirt will control fuel > injectors. If this fails, I will fall back to a manual valve that meters > fuel into the intake. The backup would be useless for starting the engine > on the ground, but from 6000ft it will keep the engine running as long as > I have fuel. > > The ignition will be handled by two Ford EDIS ignition controllers that > are supplied with an input from the Megasquirt to control advance. I'm > going with a rotary, which has two plugs per chamber. If I loose the > Megasquirt, the EDIS modules will still supply spark with a set advance. > If I lose one EDIS, spark will be supplied to one plug per chamber by the > other. > > I think the redundancy is as good as it gets in light aircraft. >


    Message 2


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    Time: 02:30:38 AM PST US
    From: "Peter Pengilly" <peter@sportingaero.com>
    Subject: EFIS as only reference???EFIS as only reference???EFIS
    as only reference??? Larry, I know that GRT uses Windows CE and I believe Advanced does also, but I also have heard that both are moving to different systems in their latest offerings (don't know what). I guess the point is that both of these systems provide some excellent functionality and are reasonably reliable, but I would use a "steam" powered back-up if my life depended on it. Peter -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Larry L. Tompkins, P.E. Sent: 21 September 2007 16:52 Subject: Re: AeroElectric-List: EFIS as only reference???EFIS as only reference???EFIS as only reference??? Peter, Can you advise which of the EFIS systems are Windows based and which are not? I know from talking to the Dynon folks at EAA Arlington that they write their own code. I am particularly interested in the Tru-Trak EFIS. It seems like some of the others have gotten in a "bells and whistles" contest and, for me at least, are reaching the point of screen saturation. I also question how well developed some of these products are when the development process seems to be continuous. (Refer to lengthy diatribe below only if you wish) Background information. There is one observation regarding the "certificated vs. non-certificated" products that I would like to make based on my long-time automotive engineering experience. When an automobile goes into production, every component has been evaluated and its controlling drawings have been signed off by a "release engineer." The pieces are produced in accordance with drawing tolerance as best as machine tools and human beings can make them. From my auto industry experience, warranty claims during the late 70s and early 80s were less than 0.25% (i.e., 1/4 of 1%) and are probably much lower today. For the auto companies I worked for, a warranty claim rate of 1/4 of 1% was deemed a serious problem and was sent to committees for root cause analysis and correction. Yes, the design was really "chiseled in stone." Yes, the design was definitely not "cutting edge." That trade-off was made so that the design worked at least 99.75+% of the time. Putting the cart before the horse My worst auto industry war stories relate to those times when there were MARKETING driven changes that were implemented without adequate testing. "Everyone" thought they would work just fine and "were required to be competitive." In many cases they were disasters and in a few cases they were recalls. How this relates to avionics It is probably true that certificated avionics products are not "cutting edge" because their certification process also "chisels the design in stone." Now think about the volume of avionics sold, the cost of testing, the cost of updating and maintaining drawings to support a small number of serial numbers that represent the length of a production run in a certain configuration. One can see that these "bells and whistles" that manufacturers think they have to have to compete in the market pose some real issues regarding reliability. A manufacturer's opinion that his product would pass certification tests is most likely just his own opinion. For many of these products we are the BETA sites. I personally subcribe to the philosphy that "one test is worth a thousand opinions." Summary As we are all aware, aviation is all about risk management. Like mountain climbing and auto racing, aviation can be especially unforgiving of mistakes, but the experiential reward is tremendous. I am not suggesting the purchase of only certificated avionics. I am suggesting that purchasers of non-certificated avionics be less in love with "bells and whistles" and really hold manufacturers accountable for highly reliable products.


    Message 3


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    Time: 05:02:21 AM PST US
    From: "Richard Girard" <jindoguy@gmail.com>
    Subject: Dual Ignition
    Peter, Upon what data does your statement, "the average mag is horribly unreliable", come from? Properly setup and serviced, quite the opposite is true, in my experience. Also your statement that the dual ignition is required by jug size is questionable, too. Last year while in class to get my LSA repairman maintenance ticket I set the up two Slick mags to go into an A75. I set the internal timing of the mags so that it was dead on for both, and the engine timing the same. The instructor was on the verge of accusing me of having OCD as I checked and rechecked until I was satisfied it was as close as I could get it. When I was finally satisfied, we pulled the plane out to the ramp and started it up. After it was up to operating temp I did a mag check. It scared the wits out of me when I got NO mag drop. Now the EIS installed on the plane only read in 10 RPM increments, so there may have been some drop, but the instrument didn't read it and I could neither hear it, nor feel it in the seat of my pants. I thought sure I had installed the P leads improperly and was ready to use the fuel valve to shut the engine down when the instructor stepped in, checked all the connections and pronounced them good. I did a second mag check, and still got no detectable drop. I pulled the throttle back to idle, closed both mag switches and the engine died just as it should. What gives, I always gotten some drop on every plane I've ever been in. We pulled out the continuity checker and went over the P leads again. Everything was as it should be. Restarted the engine, established 1700 RPM and checked again. NO drop. Shut down the left mag, let the engine run for a bit and shut down the right mag. The engine died. Restarted, shut down the right mag and let the engine run. Again, NO mag drop. Killed the left mag, engine died. I'm sure the WTFO expression on my face begged an explanation. The instructor, whose list of certs look like alphabet soup gone mad, said it's simple really. It's a very low time engine (his personal E-AB aircraft, by the way) and the students in the class had set everything up as near perfect as was humanly possible, hence no discernible mag drop. He recounted how many a long faced pilot, discouraged by the $2000 quote for parts and labor from another shop has become his loyal customer when a new set of points and careful setting of internal mag timing and engine timing has restored the mags to proper working order for less than a 1/4 of the original estimate. Now lets take the other end of the spectrum. I have and HKS700E engine on my trike. It's got 40 hours on it. My OCD tendencies when it comes to engine variables is as active as ever. It has dual CDI's for each of its two diminutive 350cc cylinders. My first "mag" check was a real upholstery clincher. I did the check at 3000 RPM and each system showed a 500 RPM drop. Needless to say I was in a near panic getting to the manuals before I called the importer. Under ignition check it said, "engine shouldn't die"! It's taken a bit to get used to, but that's the way the little engine is designed. It runs like the proverbial sewing machine, otherwise. My point is, engine design, system integration, and proper setup has much more to do with ignition system performance than reliance on OWT's about "horribly unreliable" claims. Rick -- Rick Girard "Ya'll drop on in" takes on a whole new meaning when you live at the airport.


    Message 4


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    Time: 06:40:31 AM PST US
    From: Ken <klehman@albedo.net>
    Subject: Re: ectric-List:Dual ignition
    Most OBAM aviation installs are somewhat custom with unique wiring or a unique environment for the electronics. Therefore the reliablility demonstrated by similar installations (or in an automobile) is probably not applicable. And my observation is that when stressed electronic components quit, they are more likely to do so without warning whereas a mag might degrade slowly. So even though I don't normally run my dual ignitions (single spark plug) simultaneously anymore, I take comfort in having it available every time I learn of another related auto conversion deadstick landing by someone. I have had cranksensor and coil failures on my road vehicles. One spark plug does not bother me at all, but if two were available it would simplify a dual ignition setup that otherwise uses high voltage coil joiner diodes. Dual ignition is rather pointless ;) to me if a single component failure (shorted ignition coil) can take out both systems. Coil joiners may not totally eliminate that risk but the racing circles have proven that they can dramatically reduce it. My memory is also trying to tell me that a few road vehicles resorted to dual plugs for emissions purposes. Can't really remember but it might have been for low power situations to reduce the risk of misfire and get quicker flame propagation. My current car engines misfire surprisingly often at idle power but the CAT converter keeps the emissions police happy nowadays. Dual plugs for large bore engines might reduce the need for igniton advance but I'll leave that discussion for others... Ken Peter Pengilly wrote: > >Probably because the average mag is horribly unreliable - so two >completely independent ignition systems are fitted to make sure you keep >cool. Now ignition systems are potentially much more reliable, however >dual ignition is still seen as "aviation standard". > >Peter > >-----Original Message----- >From: owner-aeroelectric-list-server@matronics.com >[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David >M. >Sent: 22 September 2007 02:50 >To: aeroelectric-list@matronics.com >Subject: Re: AeroElectric-List: EFIS as only reference???EFIS as only >reference???EFIS as only reference??? > > >Just curious, but why is it so important to have 2 plugs per cylinder? >The >Lycosaurs and etc only have 2 per cylinder because of the jug size. One > >plug alone in those engines is not enough to light the fuel evenly >regardless of swirl pattern so that's why they went to 2 per. My wife's > >brand new motorcycle has 2 plugs per for the same reason: jug size. :) > >David M. > >


    Message 5


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    Time: 11:38:36 AM PST US
    From: "Peter Pengilly" <peter@sportingaero.com>
    Subject: Dual Ignition
    Rick, In my experience the unreliability of mags is no OWT - they are. In 1300 hrs of flight time I have had 2 mags fail outright (both coil failures), a couple of spark plug failures and a harness break down giving a misfire. To be more accurate I could have written 'the average ignition system', but the sentiment is the same. In all cases the mags has been serviced as required (eg within 500 hrs for slick mags). The reason we have 2 ignitions is because on their own there are insufficiently reliable to prevent aircraft dropping out of the sky at an unacceptable rate. That we have to service the ignition system so often is another indicator. Yes typical aero engines run better with 2 sparks, but I don't think that is the primary reason. Peter -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Richard Girard Sent: 23 September 2007 13:01 Subject: AeroElectric-List: Dual Ignition Peter, Upon what data does your statement, "the average mag is horribly unreliable", come from? Properly setup and serviced, quite the opposite is true, in my experience. Also your statement that the dual ignition is required by jug size is questionable, too. Last year while in class to get my LSA repairman maintenance ticket I set the up two Slick mags to go into an A75. I set the internal timing of the mags so that it was dead on for both, and the engine timing the same. The instructor was on the verge of accusing me of having OCD as I checked and rechecked until I was satisfied it was as close as I could get it. When I was finally satisfied, we pulled the plane out to the ramp and started it up. After it was up to operating temp I did a mag check. It scared the wits out of me when I got NO mag drop. Now the EIS installed on the plane only read in 10 RPM increments, so there may have been some drop, but the instrument didn't read it and I could neither hear it, nor feel it in the seat of my pants. I thought sure I had installed the P leads improperly and was ready to use the fuel valve to shut the engine down when the instructor stepped in, checked all the connections and pronounced them good. I did a second mag check, and still got no detectable drop. I pulled the throttle back to idle, closed both mag switches and the engine died just as it should. What gives, I always gotten some drop on every plane I've ever been in. We pulled out the continuity checker and went over the P leads again. Everything was as it should be. Restarted the engine, established 1700 RPM and checked again. NO drop. Shut down the left mag, let the engine run for a bit and shut down the right mag. The engine died. Restarted, shut down the right mag and let the engine run. Again, NO mag drop. Killed the left mag, engine died. I'm sure the WTFO expression on my face begged an explanation. The instructor, whose list of certs look like alphabet soup gone mad, said it's simple really. It's a very low time engine (his personal E-AB aircraft, by the way) and the students in the class had set everything up as near perfect as was humanly possible, hence no discernible mag drop. He recounted how many a long faced pilot, discouraged by the $2000 quote for parts and labor from another shop has become his loyal customer when a new set of points and careful setting of internal mag timing and engine timing has restored the mags to proper working order for less than a 1/4 of the original estimate. Now lets take the other end of the spectrum. I have and HKS700E engine on my trike. It's got 40 hours on it. My OCD tendencies when it comes to engine variables is as active as ever. It has dual CDI's for each of its two diminutive 350cc cylinders. My first "mag" check was a real upholstery clincher. I did the check at 3000 RPM and each system showed a 500 RPM drop. Needless to say I was in a near panic getting to the manuals before I called the importer. Under ignition check it said, "engine shouldn't die"! It's taken a bit to get used to, but that's the way the little engine is designed. It runs like the proverbial sewing machine, otherwise. My point is, engine design, system integration, and proper setup has much more to do with ignition system performance than reliance on OWT's about "horribly unreliable" claims. Rick -- Rick Girard "Ya'll drop on in" takes on a whole new meaning when you live at the airport.




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