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  #21  
Old 05-30-2019, 03:53 PM
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DanH DanH is offline
 
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Originally Posted by Toobuilder View Post
Not so fast.
Those are the optimizer's arguments, and I understand them very well.

Now put yourself in the shoes of the average Joe...the guy without any deep knowledge of engines, and no desire to be a test pilot.

He doesn't care if he squeezes out three more knots, and he sure doesn't want higher temperatures; they're scary. He just wants his Bendix-injected engine to hot-start easier and cruise real lean...which a fixed timing EI will do.
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  #22  
Old 05-30-2019, 05:04 PM
dtw_rv6 dtw_rv6 is offline
 
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I think I?m near to Dan?s camp. Running Plasma III and a Pmag. I could get a fairly non advanced spark if I disconnect the manifold tube from these systems, correct?
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  #23  
Old 05-30-2019, 05:10 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by DanH View Post

Now put yourself in the shoes of the average Joe...

...He doesn't care if he squeezes out three more knots...
Since this is VAF and not the "Cessna 172 Renter" forum, I'm guessing the "average Joe" spent several thousand hours crafting an airplane because he wanted to learn some stuff and expected an efficient, high performance aircraft at the end. The average Joe buys a Cessna or Cirrus because they are "good enough". VAFers want performance, and they brag about it at every opportunity.

Anyway, I believe you missed the boat concerning my comments about temps. "Fixed timing" will result in HIGHER CHT on takeoff and initial climb than "optimized" timing because it is TOO FAR ADVANCED. You have seen my 100% power test data. My 25 degree PV engine returned the same speed at 20 degrees as it did at 30. Therefore, the factory setting of 25 is more advanced than required for that power setting and results in higher CHT and reduced detonation margin. Period. Dot.

At the other end of the spectrum (high and lean) yes, compared to fixed timing an optimized timing value will run somewhat higher temps. But they are still going to be far lower than the 100% power figure the engine is designed around. And certainly you can't suggest that the low temps observed with the combustion process hobbled by (the now) retarded fixed timing is "normal"?

The bottom line (as always) remains that the timing is either "right" or "not right", and IMHO, is a lot more important for engine performance than the "energy" of the spark.

As a final comment, your speed estimation "three more knots" is understated. I get three more knots just going from my "optimized" ROP setting and my LOP setting. That's just a small jump in an already significant advance. Making the same leap all the way from the data plate (fixed) setting would be huge - like 10 knots.

10 knots at the same fuel flow over the life of the engine is a LOT of time... Seems like the "average Joe" VAFer would gladly trade a few hours of some some tuning in exchange, don't you think?
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  #24  
Old 05-30-2019, 06:09 PM
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Quote:
Originally Posted by dtw_rv6 View Post
I think I?m near to Dan?s camp. Running Plasma III and a Pmag. I could get a fairly non advanced spark if I disconnect the manifold tube from these systems, correct?
Nope. You would need to reliably seal it somehow so it always reported ~29.92. That has risks.
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  #25  
Old 05-30-2019, 06:16 PM
YellowJacket RV9 YellowJacket RV9 is offline
 
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Originally Posted by Toobuilder View Post
Seems like the "average Joe" VAFer would gladly trade a few hours of some some tuning in exchange, don't you think?
I think the fact that the majority of us RVers still run mags is a testament to the contrary.

I built my plane, and I have a master's degree in engineering. I am confident that if I wanted to become an expert in engine timing and tweak every single ounce of performance out of my ignition, I could, eventually. But I also wouldn't half-@$$ it, because my engine is too important to me. And since I don't have the time or desire to go all-in on ignition systems, I just want what I stated previously: better performance and better reliability than a mag, which it sounds like the Surefly, maybe even with a fixed curve, could deliver. Also, I am (gasp) carbureted, so max efficiency is already out of the question.

Maybe it is either "right" or "not right", but if so, 99.99% of planes have been flying around "not right" since the dawn of reciprocating engines, so I won't feel too bad about it.

Don't get me wrong, I love the fact that there are smart, passionate people like you guys leading the way for us, and one day I'd love to have the time to join you, but until then it's all about simplicity and reliability for me. I don't need to brag about performance, I can barely get in the air with my 150 horses

Chris
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Last edited by YellowJacket RV9 : 05-30-2019 at 06:22 PM.
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  #26  
Old 05-30-2019, 06:45 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by YellowJacket RV9 View Post
I think the fact that the majority of us RVers still run mags is a testament to the contrary.

I built my plane, and I have a master's degree in engineering. I am confident that if I wanted to become an expert in engine timing and tweak every single ounce of performance out of my ignition, I could, eventually. But I also wouldn't half-@$$ it, because my engine is too important to me. And since I don't have the time or desire to go all-in on ignition systems, I just want what I stated previously: better performance and better reliability than a mag, which it sounds like the Surefly, maybe even with a fixed curve, could deliver. Also, I am (gasp) carbureted, so max efficiency is already out of the question.

Maybe it is either "right" or "not right", but if so, 99.99% of planes have been flying around "not right" since the dawn of reciprocating engines, so I won't feel too bad about it.

Don't get me wrong, I love the fact that there are smart, passionate people like you guys leading the way for us, and one day I'd love to have the time to join you, but until then it's all about simplicity and reliability for me. I don't need to brag about performance, I can barely get in the air with my 150 horses

Chris
Copy all. The advantages of EI and variable advance have been well proven in pretty much every single other spark ignition engine in existence for the last several decades. Even model airplanes have them now. There is a reason for that:. It's simple and effective. Qualities near and dear to any engineer.

That said, if one is in the market for an ignition, why not pick one that has the capability to grow along with you? Why limit yourself to some randomly developed fixed curve on the word of the manufacturer? We KNOW there are different requirements from engine to engine... Buy one that will do exactly what YOU want. Want it fixed? Fine. But you cant tell me the capability to later change your mind and set a custom curve is a deterrent, can you? After all, pilots have had control of the red knob since the beginning of time, and that is a lot more destructive to engine life than the ignition.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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  #27  
Old 05-30-2019, 07:24 PM
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Walt Walt is offline
 
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Quote:
Originally Posted by YellowJacket RV9 View Post
I think the fact that the majority of us RVers still run mags is a testament to the contrary.

Maybe it is either "right" or "not right", but if so, 99.99% of planes have been flying around "not right" since the dawn of reciprocating engines, so I won't feel too bad about it.

Don't get me wrong, I love the fact that there are smart, passionate people like you guys leading the way for us, and one day I'd love to have the time to join you, but until then it's all about simplicity and reliability for me. I don't need to brag about performance, I can barely get in the air with my 150 horses

Chris
Have owned and worked on most every type of EI out there....
My new IO370 was delivered with Bendix Mags!
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Last edited by Walt : 05-30-2019 at 07:28 PM.
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  #28  
Old 05-30-2019, 07:31 PM
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Carl Froehlich Carl Froehlich is online now
 
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Quote:
Originally Posted by RV8JD View Post
What is the advance curve of the LSE Plasma III?

Thx.
This is from the Lightspeed install manual - available on Klaus?s web page.

?During start, the system will fire at TDC for standard compression engines with ratios less than 8.7:1. At idle the strobe light should indicate 21? ? 2? when the manifold pressure hose is disconnected and 40? ? 2? when connected.

If you are using a compression ratio of 8.7:1 or higher, the timing must be retarded another 5?. If you are using the Hall effect sensor module in place of the magneto, reposition it to show idle strobe light readings of 16? ? 2? when the manifold pressure hose is disconnected and 35? ? 2? when connected.

Note that these numbers are for sea level. You can add 1 degree for each 1,000 ft of density altitude. The low number (MP hose disconnected) is the most important.?
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  #29  
Old 05-30-2019, 11:21 PM
pecanflyboy pecanflyboy is offline
 
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You guys have been busy beavers! I thought I had subscribed to the thread, and was surprised at how quiet it was.....surprise!

The Surefly is not competing with Pmag and other user adjustable EI's. There is definitely a place in the experimental market for those that want to take the time, fuel, and risk to tweak their engine to a measurable optimum. Sorry I used the term "hotrodders," as I saw it as a compliment.....even aviators are sensitive these days......SAFE SPACE!

Surefly is going to make their impact felt in the certified market, as magneto technology is rotting on the vine. Surefly is marketed as a magneto replacement that can be used in fixed or advanced timing mode. You are going to get magneto "plus" performance in a simple and reliable system. You are not going to experience huge gains in performance, as that was not the design goal. You will gain reliability and a unit that doesn't crumble out of its case at a 500 hours inspection, or have its impulse coupler self destruct into your accessory case. Have you looked inside a magneto lately? Actually, there are no inspections required on the Surefly.

I would argue that the curve is not aggressive, as the FAA required extensive testing to show that it performs safely in all fight modes. If you were able to make it user adjustable, every imaginable mode would have to be thoroughly tested to insure safe operation. Not feasible if you want to sell a unit for only $1250.

There may be future developments as the company is finally starting to generate income from the certified market. They understand that there is a desire for a backup battery when using two Surefly SIMs. They also understand the desire to have auto sparkplugs. However, like the Greek king Sisyphus, they have been pushing the FAA ball up the hill, only to watch it roll back down, for the last 3 years. Experimental products have been a low priority until now.

So, if you want an EI that you can be loaded with a curve that worked for someone else, and then test fly it to its optimum, PMag is the system for you. Great guys and a great product.

But, if you want a plug and play, reliable mag replacement that is certified, safe, simple, and reliable..........consider the Surefly.

Last edited by pecanflyboy : 05-31-2019 at 07:32 AM.
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  #30  
Old 05-31-2019, 07:41 AM
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MiserBird MiserBird is offline
 
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Pecanflyboy,

Anything in the works for a certified Surefly replacement for the Bendix D2000 / 3000 dual mags? Is the market large enough to even consider?
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