Engine Stress, Power, and Mixture Management

I posted UESP&FMM Rev6 here and on Mooneyspace.com. it has been pointed out that I have not credited other people for the work they did before me. This is true. Here are two of the posts from that discussion.

>>>>>
This seems to be a reasonable summary of other people’s work — without attribution, I note. Most of this is information presented and published by Advanced Pilot Seminars, and especially John Deakin. APS is the originator of the concepts of ICP, red box, big mixture pull. The red fin was popularized in the Cirrus community, I believe, by Gordon Feingold.
Some of this also appears to derive from writings by Mike Busch.
Skip. (PT20J)>>>>
>>>>>
To the best of my knowledge what Skip says is all true. The object of the paper is to teach an understanding of the subject matter. It is rather complex. The origin of this knowledge comes from advanced pilot seminars and the gami-injector people. Who did what I couldn't say, because I don't really know. I do know that the writing and organization is my own, and I designed the RFFA chart towards the end, but my basic understanding of this subject comes from the advanced pilot traing class that I took about 18 months ago, followed by hours of research and analysis and experience with my own airplane to create the RFFA chart that can be tailored to any engine. The material is copyrighted to ensure it is not altered, insuring the reader receives a pure dialog. I am receiving no compensation, and am not asking for any.

If you feel I have acted improperly, and want me to take this post down, I will. If you want me to add an addendum that properly credits the people that created understanding that we now consider to be fact, I can do that too, but I'll need help doing that. Petehdgs>>>>

>>>> George Braly, John Deakin and the late Walter Atkinson deserve the credit for popularizing LOP operation through the Advanced Pilot Seminars. APS, LOP and GAMIjectors go together. You can't run LOP on many engines -- especially the big Continentals -- without GAMIjectors, and you can't convince people to buy them if they think LOP is damaging to their engine.

Spark ignition internal combustion engines are complicated and a deep understanding involves delving into aspects of chemistry, combustion dynamics, and thermodynamics. Pilots are not going to sit through lectures on specific heats and enthalpy. APS uses a simple, easily described parameter -- ICP -- to illustrate what they want to teach. The concept is readily conveyed using graphs and simple mechanical principles. But it does not adequately or completely explain many aspects of engine operation. Though central to APS presentations, peak pressure is barely mentioned in most textbooks except in connection with abnormal combustion such as detonation and preignition because it is a design parameter, not an operational parameter.

The red box idea follows a logical progression. First, there is no red box if one follows engine manufacturer recommendations of reducing power to 75% for most Lycomings, and 65% for most Continentals before leaning. The problem with this procedure is that if you lean much past peak EGT the power falls off rapidly. Now, it's hard to sell injectors that turn your Bonanza into a Cherokee speed-wise. So the idea was to increase the power once safely LOP and thereby get your speed back while reaping the benefits of LOP operation. However, now there definitely is a red box because if you richen the mixture toward peak, the power will increase above the 75% or 65% allowed for lean mixtures. The big mixture pull is simply a means to simplify the procedure: rather than reduce power, set the mixture LOP and increase power, just pull the mixture back and zip through the red box before anything bad can happen.

The problem is that the red box has become expanded to include areas the manufacturers consider normal operation and we are told that to operate there is damaging to our engine. To accept this is to buy the idea that the manufacturers don't understand their product. Some have claimed this is because they didn't have the knowledge or instrumentation to understand what we know today. I think this is hogwash. If you want to learn how much was understood way back in 1940, look up NACA TN-772.

Skip (PT20J) >>>>
 
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William Pete Hodges said:
I posted UESP&FMM Rev6 here and on Mooneyspace.com. it has been pointed out that I have not credited other people for the work they did before me. This is true. Here are two of the posts from that discussion.

>>>>>
This seems to be a reasonable summary of other people’s work — without attribution, I note. Most of this is information presented and published by Advanced Pilot Seminars, and especially John Deakin. APS is the originator of the concepts of ICP, red box, big mixture pull. The red fin was popularized in the Cirrus community, I believe, by Gordon Feingold.
Some of this also appears to derive from writings by Mike Busch.
Skip. >>>>
>>>>>
What Skip says is all true. The object of the paper is to teach an understanding of the subject matter. It is rather complex. The origin of this knowledge comes from advanced pilot seminars and the gami-injector people. Who did what I couldn't say, because I don't really know. I do know that the writing and organization is my own, and I designed the RFFA chart towards the end, but my basic understanding of this subject comes from the advanced pilot traing class that I took about 18 months ago, followed by hours of research and analysis and experience with my own airplane to create the RFFA chart that can be tailored to any engine. The material is copyrighted to ensure it is not altered, insuring the reader receives a pure dialog. I am receiving no compensation, and am not asking for any.

If you feel I have acted improperly, and want me to take this post down, I will. If you want me to add an addendum that properly credits the people that created understanding that we now consider to be fact, I can do that too, but I'll need help doing that. >>>>
Click to expand...

Simply for clarity's sake, I want to point out that the "Skip" referred to above is not me, Skip Miller.

-Skip
 
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I skimmed through it and it seems good to me. In the first paragraph though, I think it's a mistake to label GA engines as tempermental, they are actually quite robust and tough. Automotive engines have had much the same issues, but the introduction of unleaded gas and the subsequent control systems facilitated by unleaded gas ( centered around the O2 sensor) has allowed for the automation of many of the steps that we are still required to do manually in aviation engines. With the introduction of UL 100 gas, I think this will start changing pretty rapidly.

I don't find GA engines hard to start, once you understand how to start them. Modern auto engines can also detonate, but have sensors to make adjustments when it happens. And I think most automobile engines, if run at 75% or even 65% power constantly would not out last a GA engine.

I skimmed the section where you advise how to run an engine that doesn't have a good CHT/EGT set up. I would not do that, engines are expensive, not worth it to me to save a few bucks on gas.
 
PaulS said:
I skimmed through it and it seems good to me. In the first paragraph though, I think it's a mistake to label GA engines as tempermental, they are actually quite robust and tough. Automotive engines have had much the same issues, but the introduction of unleaded gas and the subsequent control systems facilitated by unleaded gas ( centered around the O2 sensor) has allowed for the automation of many of the steps that we are still required to do manually in aviation engines. With the introduction of UL 100 gas, I think this will start changing pretty rapidly.

I don't find GA engines hard to start, once you understand how to start them. Modern auto engines can also detonate, but have sensors to make adjustments when it happens. And I think most automobile engines, if run at 75% or even 65% power constantly would not out last a GA engine.

I skimmed the section where you advise how to run an engine that doesn't have a good CHT/EGT set up. I would not do that, engines are expensive, not worth it to me to save a few bucks on gas.
Click to expand...

i think they feel that way only due to the fact as a whole we have forgotten how to operate an engine… the engines we use daily are like a modern airliner in terms of automation. So tempermental may not have been the word I chose, but to the vast majority of the public who would have a hard time starting a carbureted automobile it probably does seem that way. Modern vehicles have just “spoiled us” to think you turn a key and go…. The art of actually operating an engine has largely been lost. I’m looking forward to reading the full write up.
 
Mr. Hodges.
I am impressed with your "breaking this down",....However...
Paragraph 25, I believe your MP "rule of thumbs" is incorrect, unless you meant to say, "..MP with two (2) zeros added...'
I have never seem MP at 2200, or 2400, or any other number.... RPM yes, MP, no.
In which case, the numbers would be different.
(NA aircraft engine, 2500 feet field elevation, my airport... 21 inches MP, 2800 RPM / 100 equals 28.21)
Please explain where I am going wrong.
LOP is not difficult, and has been around aircraft engines for a long time.
Once a pilot has seen it done, done it two or three times, it becomes second nature.
Thank you for your reply.
Regards,
Randy
 
It is supposed to mean MP in inches + ( RPM ÷ 100). So 21+28 =49
If that is unclear I'll look at correcting it in Rev7.
Thanks for the sharp eye!
 
Mr. Hodges,
Not so much a "sharp eye", just a "why am I not getting the numbers that the form is getting??". (A senior moment, maybe?)
Thank you for your reply, good day.
Regards,
Randy
 
I saw your post before the edit. You are wound too tight for me to bother, have a good one.
 
The old Pelican Perch series by John Deakin is online, it contains much usable and informative information (such as the fact pigs do not in fact fly).
Huckster79 said:
I think they feel that way only due to the fact as a whole we have forgotten how to operate an engine… the engines we use daily are like a modern airliner in terms of automation. So tempermental may not have been the word I chose, but to the vast majority of the public who would have a hard time starting a carbureted automobile it probably does seem that way. Modern vehicles have just “spoiled us” to think you turn a key and go…. The art of actually operating an engine has largely been lost. I’m looking forward to reading the full write up.
Click to expand...
In the 80's a much younger me rebuilt a barndoor, split-window, VW panel van. It was big and un-aerodynamic and I built a dual port 1641cc with twin 36s and a collective exhaust for it. Starting was a series of actions every bit as complex as the CE150 I would learn to fly in a year or two later. Performed in the right order it always fired right up. With big "spaces" between the "sweet spots" for each of the four forward gears getting it moving was likewise a series of actions in a precise order. Driving it meant always being aware of the power curve, if you got behind it, well... Driving on the freeway meant timing every move and ignoring those horns behind me while I timed my "slingshot" on uphill on-ramps.
 
This is a reply to a poster on Mooneyspace.com. You can see his post there, under this same topic.

Eric, I apologize for my tardiness in this reply. There are reasons I have for doing things the way I have.

I am assuming you have printed this and have the 10 pages there to look at and scroll through.

The figures introduced with paragraphs 10, 15, 24, 26, and 39 are not precise. They are to look at not to measure from. They are just pictures to illustrate a point. All you need to know about 10 (75%) and 15 (65%) is that they illustrate the RED BOX, the bottom of the box is 400F CHT, and the width of the box is less at 65% than at 75% load. All of this information is in the text. ROP is on the left LOP is on the right and the dotted line is Peak EGT. In paragraph 15 I tell you to look at the 75% load box. In the next paragraph 16 I tell you to look at 65% load, which is right there to look at. Paragraphs 9 and 10 are the first discussions of the RED BOX, and there is a the 75% load RED BOX on the page to look at. The RED FIN is first discussed in Paragraph 23, and the first picture of it is at paragraph 24, then a different one at paragraph 26.

The figures introduced in paragraphs 4, 18, 21, 34, 39, and after 45 are precision figures. You can print them, measure them with an architect's scale and apply a little calculation and you will have precise measurements that are repeatable. That's what I did. The figure in paragraph 39 is a re-work of the RED FIN shown in Figure 26, corrected to follow the fuel and air curves more precisely. Everything you need to know is in the text, but you can print it, measure it, and get precise readings.

I am not a scholar. I am a diesel mechanic and a private pilot. This paper is not for scholars, it is for internet distribution for people who are curious about this subject and want to learn more without spending any money. In other words airplane pilots. Airplane pilots who are notoriously CHEAP. Like me.

Not all internet people are willing to take this at face value. Some of them want to make it their own. Some internet people are likely to pick and choose what they want and discard the rest, and then re-post it somewhere else. I'm ok with that to a point. The problem is when someone starts re-wording the document and then posting it in its altered form. For some reason people love to re-edit everything. You, yourself, are livid with me because I have not re-written or re-organized the document to meet your expectations. Within this document I have made specific recommendations for engine operations that put the reader at a point of understanding by using the paragraphs that came before as building blocks of knowledge. What do I want? I want the reader to fully understand paragraph 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, and 44. For most of the audience this means reading and understanding paragraphs 1-32 in sequential order.

Every paragraph is important! Every paragraph builds on the previous paragraph! And changing anything, in any of the previous paragraphs, could change the reader's understanding of some key element that could affect engine operation in a negative way. That means possibly, as a result of tampering with this document, engine damage or engine destruction could occur. Which if it did during critical flight operations could lead to loss of life. I take that responsibility seriously, and you should too.

Weather you agree with what I am doing or not, you have to understand the potential liability if a loss of life should occur. To that end, every page has a copyright notice and the name of the document, and my email address. Anyone can email me about this document and ask any question they want to ask. Anyone can search the internet for the key words LOP, ROP, RED BOX, RED FIN, BIG MIXTURE PULL and pull up most of the documents I used as research when creating this paper. They can't pull up any information about the RFFA chart without emailing me directly. That is because recreation of this chart is a difficult process that exceeds the confines of the principles presented here.

I will say that I puzzled and puzzled over the first version of the RFFA chart trying to figure out how to make it readily adaptable to any engine, as requested last year by a poster in POA. I have finally done that! So here is the paper to give everyone the same level of understanding that I had when I was willing to start experimenting with the operations of my own engine. So, you could say this entire paper is about paragraphs 34 and 35. If you don't get them, you haven't learned anything new.

Everything they say about me is TRUE. Good or BAD.

One Miracle at a time.
 
UESP&FMM has been removed for review.
I ask that all existing copies be deleted.

I further request that POA delete this thread and all associated material.

Thank you for your time and feedback.
 
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