How to thread drift in 720 posts!!!
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We ran a great operation at lower than 500 feet. When people you know are family and friends are in that seat you make sure that it's done right every time. We never had an engine failure partially or any thing. Running lop will not cure your own problems at all if the pilots treat the engine with content it's that simple. There are pilot and there are operators. Me at the end of the change can pick them very easily. Pilots that think they can put it over engineers are deluding them selfs.
Also our engines always made o/h.
Cheers
Also our engines always made o/h.
Cheers
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I have read the articles online at the APS site
Walter, John and Jaba have directed us there for education purposes.
Is it credible evidence to refer to yourself as a source?
I would like some peer reviewed articles printed in Aviation Maintenance journals or similar so I can research further
Walter, John and Jaba have directed us there for education purposes.
Is it credible evidence to refer to yourself as a source?
I would like some peer reviewed articles printed in Aviation Maintenance journals or similar so I can research further
LOP operated correctly in conjunction with a good EDM and well trained pilots will save not only maintiance costs, extend cylinder/valve life but will also save the price of an engine in its life in fuel savings alone.
You won't be able to use the pilots that have caused your hangar floor to be full of destroyed cylinders as an example of why you think it is wrong, for obvious reasons.
I don't think anyone is advocating running LOP at 500ft or below?
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HA! Says the guy who is so narrow minded that he refuses to be educated because it's too difficult. I'd suggest you try stepping outside your narrow minded comfort zone and let your over inflated ego allow you to accept that people know more than you think you do, but I honestly think you are too stupid for any of this to sink in anyway. Please let us know who you are so we can avoid your expert services.
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Oh humpty dumbbbbty back. As useful nothing useful to say. Typical troll by his own account.
Just a matter of interest would you like some more technical abbreviations.
Or is it a little to much for your brain to cope with.
Cheers
Just a matter of interest would you like some more technical abbreviations.
Or is it a little to much for your brain to cope with.
Cheers
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With a single probe EGT, you can KNOW that all cylinders are LOP IF the engine is running smoothly. If the F:A ratios are not even, the cylinders will be putting out different HPs and the engine will run rough. If it's smooth, then the F:A ratios are balanced.
As for Yr. Right's claim that LOP mixtures exit the combustion chamber still burning, in the usable mixture ranges, this is simply not true. For the mixture to be still burning as the exhaust valve opens, the mixture must be so lean as to be far too lean for practical use. We show several examples of this in the APS course. As one leans from peak toward LOP mixtures, the EGT falls… until the mixture becomes so lean that the EGT begins to rise with further leaning as the exhaust valve begins to open. This mixture range is so lean as to be very close to Idle Cutoff--unusable in operational conditions. This concern is a red herring.
There are a few mixture ranges where the escaping gasses actually COOL the exhaust valve. That is difficult for many to appreciate, but it has been measured.
There is MUCH refereed material in the literature. All of it agrees on the science. Everything John, Jabba, and I have been posting is completely supported in Taylor's definitive two-volume text on internal combustion as well as Haywood's excellent texts. FWIW, Taylor was the head of the Sloan Combustion Laboratories at MIT--no slacker, he. FWIW, I may be one of the few posting in this thread who has actually read both of Taylor's volumes. I highly recommend them if you have about six months to go through them. If you have another 4 months, study Haywood's text.
All of that is supported by all of the data collected by every engine manufacturer since the Wright Brothers.
This science is not arguable by anyone familiar with these multiple data sources. It is, of course, arguable by anyone with incomplete exposure to the science.
Old Wives' Tales in aviation like we are seeing posted in this thread are like snakes--they take a lot of killin'.
As for Yr. Right's claim that LOP mixtures exit the combustion chamber still burning, in the usable mixture ranges, this is simply not true. For the mixture to be still burning as the exhaust valve opens, the mixture must be so lean as to be far too lean for practical use. We show several examples of this in the APS course. As one leans from peak toward LOP mixtures, the EGT falls… until the mixture becomes so lean that the EGT begins to rise with further leaning as the exhaust valve begins to open. This mixture range is so lean as to be very close to Idle Cutoff--unusable in operational conditions. This concern is a red herring.
There are a few mixture ranges where the escaping gasses actually COOL the exhaust valve. That is difficult for many to appreciate, but it has been measured.
There is MUCH refereed material in the literature. All of it agrees on the science. Everything John, Jabba, and I have been posting is completely supported in Taylor's definitive two-volume text on internal combustion as well as Haywood's excellent texts. FWIW, Taylor was the head of the Sloan Combustion Laboratories at MIT--no slacker, he. FWIW, I may be one of the few posting in this thread who has actually read both of Taylor's volumes. I highly recommend them if you have about six months to go through them. If you have another 4 months, study Haywood's text.
All of that is supported by all of the data collected by every engine manufacturer since the Wright Brothers.
This science is not arguable by anyone familiar with these multiple data sources. It is, of course, arguable by anyone with incomplete exposure to the science.
Old Wives' Tales in aviation like we are seeing posted in this thread are like snakes--they take a lot of killin'.
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***Is it credible evidence to refer to yourself as a source?***
Only when you have done the original research.
Actually most of what we present is from other, undeniably expert sources. We do present some of what we have discovered through our own intensive, scientific research. Some of what we have discovered is still considered proprietary, so we do not discuss those things.
We make a HUGE point of telling everyone as we have done in this thread:
"Do not believe us. Do not believe anyone's opinion. Believe the data, for without data, all you are is another person with an unsupported opinion."
Only when you have done the original research.
Actually most of what we present is from other, undeniably expert sources. We do present some of what we have discovered through our own intensive, scientific research. Some of what we have discovered is still considered proprietary, so we do not discuss those things.
We make a HUGE point of telling everyone as we have done in this thread:
"Do not believe us. Do not believe anyone's opinion. Believe the data, for without data, all you are is another person with an unsupported opinion."
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***So Walter by what you have just said I and every engineer that's every replaces a cly have never done it for a burnt exhaust valve.***
That, sir, is a ridiculous statement. I said nothing of the sort. The data is clear that your assignment of causality of those burnt valves is erroneous.
That, sir, is a ridiculous statement. I said nothing of the sort. The data is clear that your assignment of causality of those burnt valves is erroneous.
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As an engineer like as all when we have a problem we look for a cause. Ie mags timing plugs etc. it not a case of change a cly and all be ok. We look at eve eying that May have cause that. And guess what. The fella behind the controls is to blame nearly all off the time. If what Walter has just said is true we would not see the damage that we see. The little red knob is a major problem in the wrong hands. A 210 in around 1985 out bankstown crashed a killed all on board just after takeoff. Reason pilot though he was pulling pitch he pulled the red knob instead and crashed. I keep saying fuel is cheap.
Cheers
Cheers
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Short answer:
During a mag check, operating on one mag, the combustion takes longer to complete since there is only one flame front. This results in less total expansion of the combustion gas (PV=nRT) since the thetaPP is occurring later in the power stroke. As the expanded volume of the 3800 degree gas changes, so does the temperature. The result is a higher EGT due to the lesser expansion of the hot gas.
It is NOT because the exhaust valve is opening during the event. By definition, half of the F:A charge is burned at the thetaPP. This is generally occurring at about 15-16d ATDC. In a single mag condition the thetaPP is retarded by about 8 degrees. This means that the combustion charge is completed by around 46-48 degrees after top dead center. The exhaust valve doesn't open until about 135 degrees after top dead center. In a useful LOP mixture the burn completion is later than the example above--maybe a thetaPP of 25 or so, but is still completed significantly before the exhaust valve is opening (about 60 degrees before it opens--give or take a tad). Another red herring of concern.
A more fully descriptive answer as presented in the APS class is not possible in this limited forum post.
During a mag check, operating on one mag, the combustion takes longer to complete since there is only one flame front. This results in less total expansion of the combustion gas (PV=nRT) since the thetaPP is occurring later in the power stroke. As the expanded volume of the 3800 degree gas changes, so does the temperature. The result is a higher EGT due to the lesser expansion of the hot gas.
It is NOT because the exhaust valve is opening during the event. By definition, half of the F:A charge is burned at the thetaPP. This is generally occurring at about 15-16d ATDC. In a single mag condition the thetaPP is retarded by about 8 degrees. This means that the combustion charge is completed by around 46-48 degrees after top dead center. The exhaust valve doesn't open until about 135 degrees after top dead center. In a useful LOP mixture the burn completion is later than the example above--maybe a thetaPP of 25 or so, but is still completed significantly before the exhaust valve is opening (about 60 degrees before it opens--give or take a tad). Another red herring of concern.
A more fully descriptive answer as presented in the APS class is not possible in this limited forum post.
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There is no RPM drop during an in-flight mag check with a constant speed propeller.
The rpm drop during a pre-flight mag check is due to the reduction of crank angle geometry efficiency due to the retarded thetaPP and the resultant loss of power.
Yr Right, can you define ThetaPP for us? Or, are you still not answering questions?
The rpm drop during a pre-flight mag check is due to the reduction of crank angle geometry efficiency due to the retarded thetaPP and the resultant loss of power.
Yr Right, can you define ThetaPP for us? Or, are you still not answering questions?
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***Um no Walter I'm fully aware what a burnt valve is and what you have just said can't happen but in real life it dose.
***
I have said nothing of the sort--and everyone here knows it.
Your misquoting and misstatements are non-contributory to a meaningful conversation.
Are you still not answering questions?
***
I have said nothing of the sort--and everyone here knows it.
Your misquoting and misstatements are non-contributory to a meaningful conversation.
Are you still not answering questions?