Walt, where are you seeing the failures in the Plasma III?
The control box, coil, pickup, etc? If the box, I’m curious where the failure points are in there.
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PMAGS or SDS
- Thread starter Retooferab
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The control box, coil, pickup, etc? If the box, I’m curious where the failure points are in there.
Walt
Well Known Member
Brain box failures mostly, the only thing I’ll do is remove and pitch in the trash. I refuse to deal with the company any longer.
RV8JD
Well Known Member
Just a data point. I have the LSE Plasma III (with the mini sensor) and an impulse coupled Slick mag on an IO-360-M1B on an RV-8. The airplane has 1425 Hobbs hours and there have been no problems with the LSE Plasma III EI. I change the auto plugs (Denso IK27) at the ACI and the ignition harness every 500 hours.
(I'll go knock on wood now!)
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I think that's totally fair. I have all of those things, perhaps I should bring them with me if I do a cross country cross country. Or I could just leave them all in a box and package it up and mark it mags then if I get stranded, have my buddy come to my house and mail the box to me. Of course I wouldn't have installed EI if I didn't think it would be more reliable, so hopefully I'll never need it, but it's certainly something to consider.
Walt
Well Known Member
A big plus in my eyes for the "Surefly" is it literally is a direct replacement for a Slick, so if you ever had a problem in the field a slick is a drop-in replacement. I'm surprised it hasn't been mentioned, I think it's a good replacement for a mag and has been certified by Lycoming (fixed timing mode).
Walt, you would like my EI. I can twist the mag hole trigger one tooth to fire at 20 degrees if one of the controllers should die; without a calculated timing signal, the Ford brick fires at what it thinks is 10 BTDC.
The brick and other components are widely available in parts stores and wrecking yards. One of the regulars here bought all the Ford parts at his local yard for $60.
The brick and other components are widely available in parts stores and wrecking yards. One of the regulars here bought all the Ford parts at his local yard for $60.
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Toobuilder
Well Known Member
Pmag will (or the older models would) hand prop with nothing more than a 9 volt battery for power. And I have hand propped my Hiperbipe and RV-8 with Pmags no problem. Ross used to say that the CPI needed one full revolution to fire, (and therefore would not hand prop), but there are some guys doing it now so not sure what’s changed.
That said, I think if you are out in the boonies with a dead ships battery and you dont have a smoke alarm to rob a 9v battery from, you will not light the Pmag by hand
That said, I think if you are out in the boonies with a dead ships battery and you dont have a smoke alarm to rob a 9v battery from, you will not light the Pmag by hand
Bill Boyd
Well Known Member
Yeah, I think it requires several sensed magnet passes to fire, so no start up on the first blade with the CPi. I'm not sure (and have wondered) if the magnet passes need to be at a fairly constant rpm so it can figure TDC better - maybe that's not a thing though. If it is, you won't accomplish that by hand-propping, especially a 6-cyl. What a workout it would be to try!
Walt
Well Known Member
I still prefer to flight plan without the requirement of having an O’riley’s or salvage yard within gliding distance!
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Luddite!
Don't you know they deliver?Seriously gang, note Walt is running a Bendix pattern mag, not a Slick type. I have no specific numbers, but the Slick/Bendix comparison is kinda like the Plane Power/B&C thing.
Walt's are likely up to date too. Even with Bendix, there are way too many old ones out there. I say this having spent some time in the facility of a new mag manufacturer and overhauler. It's eye opening to see what comes across the core teardown bench.
Good choices are the art of considered compromise. The ignition choice tends to hang on what you value most, because none of the choices are really truly awful.
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The CPI is a bit different than most with only 2 magnets with a separate sense magnet, so can't speak to their approach. Most others are like the one in Dans pic. Multiple magnets (for hall effect sensors) or ferrous protrusions / teeth (for variable reluctor sensors). They count the passage of each tooth, along with the delay time between them and need some amount of time in order to stabilize their algorithms and therefore able to accurately represent RPM. They need to see a certain amount of consistency here, as they are using the delay time to also calculate where they are from TDC and they only get one TDC event per rotation. They use the time between each sense event to determine rotational velocity and ultimately RPM. They also must use the missing tooth (longer time between events) to determine TDC. They then use this with the rotational velocity to calculate theoretical degree points across the rotation and this requires a relatively stable rotational velocity measure. All of this takes some time and often the first rotation has a lot of acceleration involved and therefore difficult for the algorithim. Most of these systems with a missing tooth arrangement need between 1.5 and 2 revolutions before they can accurately determine positions for generating spark events. More unique systems that don't use a missing tooth, like SDS or Pmag, likely can determine positions relative to TDC faster. I know a lot about how the missing tooth system work (used broadly in the auto world, at least for cranks; cams can be unique), but little to nothing about proprietary ones.
EDIT: should have been more clear that finding a rotational position is a combination of tooth passage time AND tooth counting post missing tooth.
Larry
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Bill Boyd
Well Known Member
You mean we can't do likeLuddite!
Seriously gang, note Walt is running a Bendix pattern mag, not a Slick type. I have no specific numbers, but the Slick/Bendix comparison is kinda like the Plane Power/B&C thing.
Walt's are likely up to date too. Even with Bendix, there are way too many old ones out there. I say this having spent some time in the facility of a new mag manufacturer and overhauler. It's eye opening to see what comes across the core teardown bench.
Good choices are the art of considered compromise. The ignition choice tends to hang on what you value most, because none of the choices are really truly awful.
Glock's detractors and refer to magnetos as "accessory case grenades" or compare them to Andy Griffith's crank phone in an age of iPotato's? C'mon, man... you're killin' all the fun.
Try landing a FP RV9 at 900 rpm... you would eat up a lot of runway. I am sure it could be done, but making a normal landing and taxi because you don't have 900 rpm restriction, would reduce the stress on the situation.
gmcjetpilot
Well Known Member
Has any one run automotive plugs with a magneto? I'd ve curious how it works and gap used. I would think a Slick Mag woukd have a bit of trouble with 0.035 gap. Aircraft plugs are about 0.018-0.022. They do that because they have to, to assure spark. B
you can buy single electrode Aircraft plugs but are very expensive.
gmcjetpilot
Well Known Member
Normally you have one p-mag and another ignition, p-mag, magneto, LSE... that kills your argument. Would you fly on one ignition, be it obe P-Mag or dual electrically dependent ignition on back-up battery only. No.
As far as flying a dual electrically dependent EI units, loss of both main and back up electrial power is possible. Rare bur possible.
Senerio above, having electrical issues, landing, having lunch, taking off again all on back up power is funny. Seriously you all who need a battery for engine to run, best make sure the main electric system (alternator, main battery) AND back-up battery are 100%. Seems obvious, but I have seen weird choices.
As pointed out above the backup electrical system, especially batteries, need to be tested (daily) and maintained. If your main battery is dead, I would never jump it and go fly, with the idea I have a 2nd battery. Best to recharge and check it. If EITHER main OR back-up batteties are weak, I wouldn't fly. I say this from experience of others. If your main battery is not starting engine well, investigate and replace, especially or dual EI that needs battery pwr.
Regarding P-MAG min RPM to run on internal power varies, 800 to 900 RPM, typical. The fixed pitch RV-9 runoff runway senerio, that is a stretch pun intended. I recomend not running off runway. May be land on longer runway, use those brake thingy stoppers. Ha ha. May be have on P-Mag and one regular Magneto? That is a very good setup. One EI is 70% of gain and 2nd EI 30% more.
How to do run up of P-MAG? See manual (on line pdf). It's same as magneto, run up RPM, L only, R only, with extra step of turning off external power to respective P-MAG you're checking, momentarily. Nothing happens, solid. I have pullable CB's for each P-Mag but switch can be used. They are wired separately from the main bus. It's all in the manual on Emag Air's website. It's detailed. ONCE a year or when ever you feel like it, you do a stress test. At 1200 RPM, running one P-Mag, you remove ships power from ignition and slowly lower RPM to find min RPM it will run. As stated 800 RPM is typical min RPM.
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This is a very real limitation of the pmag. Imagine a scenario where your electrical system failed. You are running the engine via the pmag generator and now landing. Pull the power back to idle abeam the numbers and the engine quits because you went below 900 RPM. Hope you have practiced engine out. You should know that it doesn't recover from this without ship power unless you have some special starter that spins over 900 RPM.. This scenario does not exist if you used the SDS or any other EI with a dedicated backup battery. Just wanted to mention this as some seem to blindly state that the PMAG is SOOO superior due to it's self power generation.
Larry
andoman
Well Known Member
Won’t air loads at normal approach speeds keep the RPM above 900 RPM?
This is an aerodynamic question, not a specific EI point.
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Toobuilder
Well Known Member
To be fair, I had this same discussion at Copperstate with Brad some 20 years ago and he stated that one should never actually get below the cutoff RPM as long as the airplane was still flying. And In all those years I cant recall any windmilling prop slower than 1200+
don't know. I have no failure modes that are dependent upon prop RPM, so never tested it. If I had Pmags, I would certainly explore it. If my engine is dead and am slow for landing, the last thing I want to look at is the tach. Pretty sure I would be busy looking out the window and at my airspeed.
gmcjetpilot
Well Known Member
Is it really a limitation Larry? Senerio you say. ;-)
- Depending on FP, metal vs wood the "residual" thrust is higher than Constsnt Speed props regardless of idle RPM. Limitation of fixed PROP is higher residual thrust at idle. This is NOT a limit of P-MAG.
- Define what "EAT" the runway up? means? Extra 100 feet? 500 feet? Is this a big deal? Doubt it.
- RPM on approach at Vso × 1.30 on 3 deg gliide path for FP RV's (all of them) is above 900 RPM. Reduce power earlier to 900 RPM to arrive at round-out flare at lower speed. Fly lower gliide path. Slip to control speed until near touchdown.. Lots of that pilot stuff you can do lo mitigate a tiny bit more idle thrust (really lack of prop wind-milling drag, not much thrust).
- Min idle RPM for a Lyc is 650 RPM BUT Lyc Recommends 800-1000 ground or air, oil pressure and cam lubrication. You don't want to stay near 650 RPM for extended periods.
- Constant speed prop flight idle on approach is about 1200-2100 RPM. No real limit.
- If worried run one regular magneto.
- If runway is critical, in flare go to throttle idle, land, engine runs or quits, land.
- If you fly off PLUS +3000ft hard runway like most of us fly off of (typically 5000 ft) and you can't land with 800-900 RPM, divert to longer runway. (I know some fly off 800 ft grass strips, talking typical).
- RV's land shorter than most high performance EAB and Std Cert aircraft even with FP and 900 RPM. Go fly a Long-EZ.
- Don't get a P-MAG if you lose sleep over this non problem problem.
- This is being pedantic about P-MAG's. No one said P-MAP is "SOOO superior". This RPM limit is a limit, a minor limit, not critical, non issue.
- The fact P-MAG's are electrically independent is cool. Clearly no competition does this. People who are Pro Brand X want to dismiss and minimize this feature.
- Buy any EI you like. However if Battery is needed to make spark, better maintain that battery or the batteries to a high degree, including proactively replacing. A WEAK start battery with a 6 year old back up battery that has been neglected might give you a false sense of security.
- Disclaimer I have nothing to do with P-Mag except being a satisfied customer.
- I think all EI's offer an advantage over magnetos. I think all EI's offer tye same or similar performance, if not you would hear about it. MANY run mixed EI's if two brands. They find littke difference. However magnetos are still good, and they are still around because they work well, especially for casual local fun flying.
- With any EI and all things in aviation know the limits. (I recall Clint Eastwood said that.)
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Carl Froehlich
Well Known Member
This is very misleading. For example if you are running SDS or other ship power dependent engine stuff your engine simply stops at loss of electrical power. With a pMag the engine continues to run, and most airplanes I know are above 800 RPM on final all the way to the runway.
I again caution about the utopia associated with backup batteries to keep the engine running and/or continued IFR flight. I’ve seen too many horrible backup battery installs. Those of you running the per instruction Lightspeed backup battery install are at the top of my list of what not to do.
Build what you want but know how it works AS A SYSTEM. Here I view just adding backup batteries as bandaids that some builders/buyers install then forget. The other rule is to test THE SYSTEM through likely failure modes to make sure you can live with the resulting degraded operation. If not, then go a back and fix your power distribution design.
I have two identical ship batteries on a power distribution system that has backup operating modes to mitigate likely system failures. I have no standalone backup batteries and consider the system to be very redundant for IFR work.
Carl
Toobuilder
Well Known Member
Carl, are you familiar with the SDS CPI-2 backup power architecture?
I think this points to the experimental nature of EAB. If you have a p-mag probably should do some testing with a good battery to see what it would take to get below the cutoff RPM so that you are prepared if you ever have a power failure.
And with SDS, might want to try hand propping to see if it can be done.
That's one solid pro for mags is that how they fail and what to do about it is well understood my most pilots. If your airplane is different, probably should figure out exactly how it's different.
And with SDS, might want to try hand propping to see if it can be done.
That's one solid pro for mags is that how they fail and what to do about it is well understood my most pilots. If your airplane is different, probably should figure out exactly how it's different.
Carl Froehlich
Well Known Member
Yes, I‘ve read the install manual. I will say that IF the before flight testing requirements are followed the pilot will have some confidence that the engine can run at least for some time on backup power. But:
- I did not see (perhaps I missed it) install instruction recommendations on how often to replace this battery. For these Panasonic batteries I’d guess replacement every two years to be reasonable.
- I did not see (perhaps I missed it) on testing the system on the backup battery to determine actual time the engine will run on the backup battery.
- I consider this one function backup battery to be a waste of weight as better options for backup power modes for the entire airplane can be incorporated with other designs. But that is a longer discussion.
So for the conscientious builder/buyer this system will keep the engine running for some period of time. I worry about the less than conscientious builder/buyer that becomes complacent and does not do the required checks after each engine start, measurements on what the system will actual do, battery replacements, etc.
Side note - it would seem to me that system testing to verify what it will do would be required to write the Emergency section of the POH for immediate and supplemental actions.
Carl
That kills this entire thread..... But thanks for the thousands of words that you have typed here to educate us.
newt
Well Known Member
My fixed pitch cruise prop doesn’t get below 930rpm on a 3° approach until I’m on the ground.
In the run up bay, the pmags are still self generating at 850rpm.
At normal flying speeds, I don’t think I have anything to worry about. Might have a problem if I decided to practice idle power stalls during a total electrical failure with a flat battery
- mark
Interesting points.
In my install I disabled the battery charging option and tied the battery input to my aux battery (ETX104) which is charged by a little 8 amp B&C alternator on the vacuum pump pad. My aux electrical system does not tie into my main system in any way. There are no bus ties or ability to jumpstart myself. The Aux system is completely isolated.
This means that in my install, the main bus can short to ground and I do exactly nothing and everything keeps working. My avionics that have dual inputs (most of them) keep going, and my electrical system swings over to my aux bus and lights the fault light.
My system is tested on every startup with the following switch logic (laid out on the panel in a row):
1. Master on (connect main bus to main batt and tie the main alt field to main bus).
2. Aux on (connect aux battery to aux bus) This boots my G3X so that I can see oil pressure at start and proves that the aux battery works. I should probably look at volts at this point.
3. Ignition 1 on (ties main ignition to main bus for start)
4. Ignition 2 on
5. Start switch
6. Aux alternator on (ties aux alternator to aux battery to charge it).
7. Avionics master on (ties avionics to master bus which regulator is set .7 volts higher so avionics swing to it).
8. Ignition test (this switch is momentary up/down and tests ignition boxes.
So, I chose to have the more complex electrical system in order to use the same battery to boot my avionics in an isolated way which also tests the battery to some degree, however one of the major points to the CPI-2 is that someone that doesn't want to go sharpen pencil and think about electrical system can simply install the default way and have the fail over of a redundant electrical system without any thought or consideration on the matter, which is what I think makes it competitive with the p-mag. You don't need to invent anything, failover is automatic and dedicated if you just follow the manual.
I do agree you need to test your battery, but I also think you need to test the little generator and inspect bearings. Some are more comfortable with the mechanical aspects, while I'm more comfortable with a battery. I can simply leave my avionics on for an hour while changing the oil and that tells me that I'm going to have some runtime if I have dual alternator failure.
Toobuilder
Well Known Member
The benefit of this architecture that puts in at least on par with the Pmag generator is the same argument that keeps the Pmag as popular as it is: the manufacturer did the thinking for the consumer. Yes, there are some claptrap electrical systems out there just as there are some real shade tree maintainers, but if the CPI-2 battery is maintained, then as a system, it is AT least as reliable as a well maintained Pmag During the unlikely event of a total electrical failure. Other EI’s rely on the skill and ingenuity of the builder to function when needed in an emergency, so there is considerable variation there - the CPI-2 can’t really be lumped in with that group because SDS has gone to great lengths to make the switchover a “no brainer”.
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