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Rocket TIT Test?

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Back in 2013, David Mazer posted: "The procedure is simple, and in the Rocket POH, lean to peak TIT.  It should peak at 1650. I have been all through my 9-page Rocket Airplane Flight Manual Supplement, dated October 18 1995, and I find no mention of a TIT test procedure.  Was the manual updated at a later date?  Does anyone have a verbatim copy of the procedure David refers to?

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Spam,

your posts are near unreadable...

Something has selected a font style that appears close to gray on white...

Try resetting your font settings to something more reader friendly...

It will help getting responses to your questions...

Best regards,

-a-

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6 hours ago, SpamPilot said:

Back in 2013, David Mazer posted: "The procedure is simple, and in the Rocket POH, lean to peak TIT.  It should peak at 1650. I have been all through my 9-page Rocket Airplane Flight Manual Supplement, dated October 18 1995, and I find no mention of a TIT test procedure.  Was the manual updated at a later date?  Does anyone have a verbatim copy of the procedure David refers to?

The procedure for what? Leaning? The quotation without context makes no sense. There is no such thing as a "TIT test" so I can't quite guess what you may be after to try and help.

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I believe on one of the performance pages there is a line where it says "verify TIT accuracy each flight" That may be what is being alluded to.

Brian

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1 hour ago, Vno said:

I believe on one of the performance pages there is a line where it says "verify TIT accuracy each flight" That may be what is being alluded to.

Brian

The manual does say check accuracy every flight - which consider to be quite excessive.  I check either once in a while, or after something has been changed - such as new spark plugs, etc.

The target is to check if a specific engine setting that is meant to result in 1700TiT indeed results in 1700 as the peak.

That setting is at 8000- to 12000ft, 33'' 2400 starting at full rich, then leaning looking to peak which should be occurring at around 19gph. This is a HIGHLY Redbox setting and also the TiT will not be happy running that hot so this is declared as a <1min transient test, and I find it very creepy so I do it in less than half that time.  20-30 seconds.  Any faster and you would be sweeping so fast that you are not getting the actual readings of the setting.  The instruments will not be responding fast enough.

My TiT has been pretty stable, so that when I do this I always indeed read 1700+/- 10, still showing just these same settings even after I had a turbo replacement about a year and a half ago.

This is very important to do - so say you get a peak reading of 1650 (and probes will tend to read low as they age), but by the setting you are actually at 1700.  Then you might be inclined to think you are fat and happy at a normal cruise setting running ROP and 1550, but actually that instrument reading is corresponding to (add 50 since 1700-1650=50), 1600 in reality, which is higher/closer to peak than you realize so higher ICPs than you would want.  Therefore you would be leaned to inside Redbox, which is hard on the long term wear of your engine.

I suppose this is still the archaic way to run your engine since by normal modern Redbox procedure methods you would lean s certain number of degrees rich, or lean of peak, irregardless of what peak you are reading.  And by the way, at a cruise setting, say 31'', 2300, the peak will not be as high as 1700 so don't use the 1700 to inform your idea of how far you are from peak.  You would want to be doing it off the normal peak of the day.  OTOH also I consider the book fuel flows to be conservative and safe and cool.  Say for example 30'' 2200 is 18gph which results in say 1480Tit (altitude dependent, etc), and very very cool cylinders.  Cylinder temps are also important to watch during all operations.  The cylinders will also give you an idea if you are running the combustion process too close to peak/too much pressure as they will get hot.  I don't consider though that this is the ideal setting if it is too conservative since not only would you be using more fuel than necessary (ROP) but too much fuel fouls up the system - plugs. cylinders...etc all get yucky.

The book entry is included.  Anyway this was a question about checking your TiT calibration test and that is included.

screenshot_233.png

Edited by aviatoreb

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5 hours ago, aviatoreb said:

The manual does say check accuracy every flight - which consider to be quite excessive.  I check either once in a while, or after something has been changed - such as new spark plugs, etc.

The target is to check if a specific engine setting that is meant to result in 1700TiT indeed results in 1700 as the peak.

That setting is at 8000- to 12000ft, 33'' 2400 starting at full rich, then leaning looking to peak which should be occurring at around 19gph. This is a HIGHLY Redbox setting and also the TiT will not be happy running that hot so this is declared as a <1min transient test, and I find it very creepy so I do it in less than half that time.  20-30 seconds.  Any faster and you would be sweeping so fast that you are not getting the actual readings of the setting.  The instruments will not be responding fast enough.

My TiT has been pretty stable, so that when I do this I always indeed read 1700+/- 10, still showing just these same settings even after I had a turbo replacement about a year and a half ago.

This is very important to do - so say you get a peak reading of 1650 (and probes will tend to read low as they age), but by the setting you are actually at 1700.  Then you might be inclined to think you are fat and happy at a normal cruise setting running ROP and 1550, but actually that instrument reading is corresponding to (add 50 since 1700-1650=50), 1600 in reality, which is higher/closer to peak than you realize so higher ICPs than you would want.  Therefore you would be leaned to inside Redbox, which is hard on the long term wear of your engine.

I suppose this is still the archaic way to run your engine since by normal modern Redbox procedure methods you would lean s certain number of degrees rich, or lean of peak, irregardless of what peak you are reading.  And by the way, at a cruise setting, say 31'', 2300, the peak will not be as high as 1700 so don't use the 1700 to inform your idea of how far you are from peak.  You would want to be doing it off the normal peak of the day.  OTOH also I consider the book fuel flows to be conservative and safe and cool.  Say for example 30'' 2200 is 18gph which results in say 1480Tit (altitude dependent, etc), and very very cool cylinders.  Cylinder temps are also important to watch during all operations.  The cylinders will also give you an idea if you are running the combustion process too close to peak/too much pressure as they will get hot.  I don't consider though that this is the ideal setting if it is too conservative since not only would you be using more fuel than necessary (ROP) but too much fuel fouls up the system - plugs. cylinders...etc all get yucky.

The book entry is included.  Anyway this was a question about checking your TiT calibration test and that is included.

screenshot_233.png

Thanks for explaining it Erik.

We have much better ways of leaning these days as Erik touched on in his last paragraph.

Leaning by using TIT as a proxy is a terrible way to do it by today's standards. I can't imagine operating a turbo aircraft without a modern engine analyzer. With a modern engine analyzer we know we want we to have our richest cyl a certain number of degrees LOP, or our leanest cyl a certain number of degrees ROP based on the percent power we are operating. That's the ONLY way to ensure all cylinders are truly at the target number of degrees either ROP or LOP. Gami provides excellent guidance on what that target should be for both ROP and LOP in their AFMS for their injectors and this is good approved guidance regardless of whether your using Gami injectors. Without an engine monitor, you have no way of determining this critical info and would do better to stick to very rich ROP settings. Otherwise you'll be for a surprise like many people that lean by TIT to find out that not all there cylinders are as lean or as rich as they thought. So only after you do your due diligence and lean properly to ensure you're operating where you want to be, and understand where your TIT actually is relative to your EGTs, only then should you begin to rely on using TIT as a proxy. But you should still verify this from time to time. Mike B takes this a step further and knows his engine so well that he uses CHT as a proxy to lean, but he is doing this at very low power settings (<65%) where it doesn't matter where one leaves the mixture. At 65% and above, you need to be much more precise on how you manage mixture.

So my advice, ignore this old and very poor advice and learn how to use a modern engine analyzer to do it efficiently and safely - or stick to very rich ROP power settings which may not be as efficient but will ensure all the cylinders are out of the red box.

Edited by kortopates
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Thanks, aviatoreb, for responding so precisely to my query!  Exactly what I was hoping to see - a copy of the manual page that describes the TIT test procedure (which I see is actually called "TIT Check").  This tells me that my Rocket flight manual is *not* the same as some of the other Rocket flight manuals out there.  As an original source, it also clears up some of my confusion related to other posts where the procedure was not quoted accurately.

Now I'm motivated to find a copy of this (newer?) version of the Rocket AFM and see what else I might learn from it, as compared to my AFM.

Not sure how this became a thread about whether you should or shouldn't lean by using TIT.  Not what I was asking about.

carusoam, please stop criticizing my choice of font.  Untold numbers of professional communications have used Courier successfully since the Selectric came out in the early 60's.  At least in this thread, it didn't prevent me from learning what I hoped to learn.

Edited by SpamPilot
typo

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It’s all about you, Spam... :)

I’m just trying to help you get more support...

 

I do like the cognitive challenge though...

There is a reason the selectric got wiped off the planet... Siri doesn’t even recognize it as a name...

 

So... not being critical... call it trying to be helpful.

Different computers display things differently... What you chose for your set-up, Just happens to be hard to read on other people’s set-ups... did you know?

I’m OK with your choice, just can’t read more than a sentence or two... :)

Best regards,

-a-

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Actually, no, it doesn't display differently on different computers, kindof a major point of web browsers, unless you're making a pre-Windows XP/IE8-era statement about sub-pixel rendering, in which case the differences would be slight at normal reading distances.  I think what you may be reacting to is the monospaced nature of the font, which has the drawback of making most text less compact (longer horizontally).  It does, however, have the advantage of serifs, which are held to make words easier to read (Merriam-Webster's Manual for Writers and Editors, p. 329).  In comparison, sans-serif fonts such as Arial, which you and most others use on this website, are held to be somewhat less readable, other things being equal.

Selectrics didn't get wiped off the planet due to the choice of font.  In any event, the font lives on.

I'll go with meaning, diction, and grammar as far more important for effective communication than font choice, except in the extreme cases of doctors' and my own handwriting.

Edited by SpamPilot

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22 minutes ago, SpamPilot said:

Actually, no, it doesn't display differently on different computers, kindof a major point of web browsers, unless you're making a pre-Windows XP/IE8-era statement about sub-pixel rendering, in which case the differences would be slight at normal reading distances.  I think what you may be reacting to is the monospaced nature of the font, which has the drawback of making most text less compact (longer horizontally).  It does, however, have the advantage of serifs, which are held to make words easier to read (Merriam-Webster's Manual for Writers and Editors, p. 329).  In comparison, sans-serif fonts such as Arial, which you and most others use on this website, are held to be somewhat less readable, other things being equal.

Selectrics didn't get wiped off the planet due to the choice of font.  In any event, the font lives on.

I'll go with meaning, diction, and grammar as far more important for effective communication than font choice, except in the extreme cases of doctors' and my own handwriting.

Sorry, I have to strongly disagree. The only text above that stands out as being readable is perhaps what you bolded or changed fonts for. (e.g., Arial and "Merriam-Webster...") I have no clue why this isn't obvious to you unless you're mistaken about "it doesn't display differently on different computers" since the difference  are night and day between your post and mine - and everyone else's for that matter. Half of us also use a software app called Tapatalk - that also can introduce differences in display quality of text. But looking at your posts in Tapatalk they are considerably more readable than here on my Windows 10 PC. 

I certainly agree with you that "meaning, diction, and grammar" are important, but only if we can see it to read it! I highly suggest just sticking to the default font - its works and enables your "meaning, diction, and grammar" to come through clearly. Certainly not trying to be critical, but its obvious from your comments you apparently may not be seeing how difficult it is to read your postings. So offering a second opinion in the spirit of trying to be helpful.

BTW, the good news is that you do have the FAA approved AFMS for your Rocket. Its only unapproved supplemental info your missing, standby and somebody is likely to have a digital copy that they can share with you. But beware, leaning recommendations on the power schedule is some of the worst places to leave the mixture based on the science we have today. 

Edited by kortopates
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I ALSO strongly agree with @carusoam and @kortopates.  If not having been a Rocket question (for which I might be the highest time Rocket pilot “active” on this forum), I’ve passed over prior posts by you because I find the font difficult to read.  I no longer fly it as I have moved up.  But I’ve stuck around this forum because I felt, at least occasionally, I can contribute something useful from my 23 years of Mooney ownership (and 25 years working on them).   

  I won’t go where some on Beach Talk went with me ( and a few just recently with a new member here) indicating “senior members “ should be off limits for newer posters to “question” or “ disagree with”.  All members should have that option without getting their hands slapped.   I no longer participate on Beach Talk for that very reason (and I have considerable Bonanza time as well).   I WILL say though, Anthony ( @carusoam ) and Paul ( @kortopates ) are contributors that are both knowledgeable and respectful, and I DON’T skip past any of THEIR posts.  

Lastly, I hope you enjoy your ownership experience with your Rocket half as much as I did.  It took an amazingly more capable and faster plane to move me off my Rocket.  It’s an tremendously capable airplane.  So impressive my expectations of a 3-5 year build on its replacement took 17 years because of how well it performed for me.  

Tom

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I always laughed when I’d see the name @SpamPilot with the old school monospaced serif font. I always sortof assumed the little tags on the corners of the characters were to aid in readability on things that involved metal typeset and pressing ink. If you had a character that was missing a little ink in the middle of a line, your mind completes the line and you don’t notice. It also may have made casting the typewriter keys, Selectric wheels or press type less problematic. I believe the stories of it having better readability on print has to do with inconsistencies in print that involves ink, pressure and castings. 

The exception is that I always use some variant of courier for writing software because it’s a universally available monospaced font. 

I believe the most readable font for CRTs is green sans serif on black, like the old green screen terminals, and for many of the same reasons. CRTs were not always perfectly in focus and staring at them for extended periods was hard on the eyes. 

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