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Tit
- Thread starter jukelemon
- Start date
Glendale, AZ
- Aircraft Type
- 112TCA
- Reg Number
- N91GM
- Serial Number
- 13184
Re: T i t
Re: T i t
Don't know about the hot shot but the TCA has a redline of 1725 and I run it between 1625 and 1650.
Re: T i t
Don't know about the hot shot but the TCA has a redline of 1725 and I run it between 1625 and 1650.
jukelemon
New member
Louisville, KY
- Aircraft Year
- 1977
- Aircraft Type
- 112B Hot Shot
- Reg Number
- N377SB
- Serial Number
- 526
Re: Tit
Thanks.
That is what I have been using as well. Puts me around 11 gph at 65-70% power setting
Thanks.
That is what I have been using as well. Puts me around 11 gph at 65-70% power setting
Nr. Albany, GA
- Aircraft Year
- 1974
- Aircraft Type
- 112 Hot Shot
- Reg Number
- N1182J
- Serial Number
- 155
Re: Tit
Jason.
Once you have you MP and RPM set slowly lean the mixture watching the TIT until you reach peak TIT, then enrich the mixture 100 degrees and this will be the TIT that I used. I then use that figure for the rest of the flight.
It is always under 1650, if I remember correctly it is about 1500 depending on the day.
That is the way I always do it but others may have a better way.
Life is a barrel of fun.
Jason.
Once you have you MP and RPM set slowly lean the mixture watching the TIT until you reach peak TIT, then enrich the mixture 100 degrees and this will be the TIT that I used. I then use that figure for the rest of the flight.
It is always under 1650, if I remember correctly it is about 1500 depending on the day.
That is the way I always do it but others may have a better way.
Life is a barrel of fun.
jukelemon
New member
Louisville, KY
- Aircraft Year
- 1977
- Aircraft Type
- 112B Hot Shot
- Reg Number
- N377SB
- Serial Number
- 526
jukelemon
New member
Louisville, KY
- Aircraft Year
- 1977
- Aircraft Type
- 112B Hot Shot
- Reg Number
- N377SB
- Serial Number
- 526
Re: Tit
It certainly seems like I have a fixed gear now. I need to amend the POH for climb at 200 fpm and cruise speed of 90 kias
The above sounds good for settings. Seems like I am a little richer than most as I have more around 1450 at 25/2400-2500
LOL...now that was funny/clever.I target 1550F, 25"MP, 2400-2500 RPM.
Of course since you've converted your Commander to a fixed-gear configuration all bets are off...sorry I just couldn't resist.
It certainly seems like I have a fixed gear now. I need to amend the POH for climb at 200 fpm and cruise speed of 90 kias
The above sounds good for settings. Seems like I am a little richer than most as I have more around 1450 at 25/2400-2500
mrogers641
New member
Dillon, MT- Iowa Falls, IA
- Aircraft Year
- 1978
- Aircraft Type
- 114 Hot Shot
- Reg Number
- N5842N
- Serial Number
- 14390
Re: Tit
Im sure Jim Parker might chime in here but I really think theses guys know what they'd doing regarding flying Turbos or TurboNormized.
http://www.taturbo.com/frames.html
Marty
PS if your after more speed. The first place I'd start is with your rigging. Some Commanders can become terribly out of rig.
Im sure Jim Parker might chime in here but I really think theses guys know what they'd doing regarding flying Turbos or TurboNormized.
http://www.taturbo.com/frames.html
Marty
PS if your after more speed. The first place I'd start is with your rigging. Some Commanders can become terribly out of rig.
JimParker256
New member
McKinney, TX
- Aircraft Year
- 1965 Champion 7ECA
- Aircraft Type
- Other
- Reg Number
- N9502S
- Serial Number
- 243
Re: Tit
Well, I was going to stay out of it, because I haven't flown a 112 Hot Shot, and don't know the equipment in the plane.
But from what I learned in the Advanced Pilots Course (APS), leaning to a "magic" TIT setting is not necessarily the best thing for your engine. So, at the risk of once again being accused of writing a novel, I'm going to address it after all...
TIT is important, because you don't want to overheat the turbo, and equally important, you don't want to overheat the exhaust pipes themselves. Burning through an exhaust pipe in a turbo-charged airplane is high on my list of things to avoid!
But TIT is NOT a substitute for all-cylinder EGT readings for leaning an aircraft engine. Leaning by TIT would "assume" that all the cylinders reach their peak EGTs (the measure of their individual mixture settings) at the same mixture adjustment where peak TIT was recorded.
In fact, our aircraft engines have notoriously bad intake and distribution designs that practically guarantee that each cylinder receives a different volume of fuel and air than does any other cylinder. The APS folks describe our aircraft engines as a collection of single-cylinder engines driving a common crankshaft.
Why does that matter? Well, the main thing is that at any given mixture control position, every cylinder's "actual" mixture is slightly different, meaning that one cylinder is leaner than all the others and one cylinder is richer than all the others. That spread can be significant - especially in carbureted engines, which create even wider disparity in cylinder mixtures... But fuel-injected engines aren't immune from this, either. Most "factory" injected engines will have a GAMI Spread (measured by the GAMI Lean Test) of somewhere between 1.0 gph and 2.0 gph. Some are better than that, and some can be even worse. (As a side note, GAMI sells flow-matched fuel injectors which should bring your fuel-injected engine's GAMI Spread down to 0.5 gph or better, which results in a much smoother engine under all circumstances. This is particularly important if you want to operate LOP with a nice, smooth engine.)
Anyway, with a substantial difference between each individual cylinder's "actual" mixture condition, a single-point TIT reading is NOT going to tell you where your engine (meaning the entire collection of those individual single-cylinder engines) is operating on the continuum from ROP to PEAK to LOP. It's going to give you an "averaged" result that is better than a single-cylinder EGT gauge (as the factory delivered them), but nowhere near as accurate as an "all-cylinder" engine monitor.
It makes sense that if I want to operate my engine ROP, I would want ALL the cylinders to be ROP. The reason for that is simple. When operating ROP, if my engine's CHTs reach a temperature that is unacceptable to me, the solution is to enrichen the mixture. This will drive the EGTs down, lower the Internal Combustion Pressures (ICP) in the cylinders, and in turn reduce the CHTs.
Conversely, if I want to operate LOP, I want to be darn sure that ALL the cylinders are LOP. The logic is equally simple - when operating LOP, and experiencing higher-than-desired CHTs, the solution is to lean the engine even further. I know - some of you think I'm nuts at this point, but it's true! You see, "PEAK" EGT means exactly that: the highest EGT measured by the instrument. As you add more fuel (richer mixture) to a "peak" EGT mixture, the EGT goes down. Likewise, as you reduce the fuel (leaner mixture) from that "peak" EGT mixture, the EGT will likewise go down.
But since this isn't a ROP vs LOP discussion, let's table the LOP discussion, and get back to the "book" procedures. After all, Lycoming says LOP operations are "prohibited" (other than briefly while leaning to find the peak EGT values).
So, if I lean by TIT, I'm almost guaranteed that at least one cylinder will be ROP and at least one cylinder will be LOP. If my GAMI Spread is within that 1.0-2.0 range, when I enrichen TIT to 100ºF above peak TIT, I am almost guaranteed to have one of my leanest cylinders wind up with a mixture that is right about at 40ºF ROP. Why is that a bad thing? Well, it just so happens that 40ºF ROP is precisely where ICP (and CHT, which parallels ICP as mixture changes) reaches its peak value. So now I'm operating my engine where one (or more) cylinders are almost guaranteed to be at their highest operating CHT... And high CHTs are not a good thing for engine longevity.
By leaning your engine with an all-cylinder engine monitor, you can observe ALL of the cylinders, and note when the FIRST one reaches peak EGT reading. And THAT is the starting point for ROP operations. Now I can realistically decide "Do I want to operate at Best Power or Best Economy for this flight?"
If Best Power is my goal, Lycoming says to adjust the mixture so that the leanest cylinder (the first to reach peak EGT as you lean the engine) is 100ºF lower (on the rich side) of its peak EGT reading. The APS folks would recommend that if you're truly wanting to go as fast as possible, and operating at "Best Power" (75%), you should adjust the mixture to more like 150-200ºF ROP.
If Best Economy is my goal, Lycoming says to adjust the mixture so that leanest cylinder is at the peak EGT reading. While Lycoming doesn't address the reason for this, it is technically the closest they can get you to the point of maximum fuel efficiency without operating LOP. The APS folks would suggest that if Economy is the goal and you are restricting yourself to ROP operations, you should operate at 60% power (or less) and with a mixture adjusted to peak EGT.
I'm attaching the "Landmarks.pdf" file to this post. It graphically depicts the four items I talked about in the post (EGT, CHT, ICP, and HP), along with one I didn't really discuss (1/BSFC, which is the inverse of Brake Specific Fuel Consumption). That last one is a measure of fuel efficiency. The chart is set up so that all the values are plotted as you go from Rich (left side of the chart) to Lean (right of the chart)
The five "Landmarks" on that chart are as follows:
1) the point where EGT is at its highest value (Peak EGT). Note that EGTs go down both to the left (richer) and to the right (leaner).
2) Peak CHT - occurs at approximately 40ºF rich of peak EGT
3) Peak HP (maximum power output) - occurs at approximately 80ºF rich of peak EGT
4) Peak Efficiency - occurs between 40-70ºF lean of peak EGT. Note that if you ignore the LOP side of the chart (everything to the right of the dotted black line), best efficiency would occur at peak EGT.
5) Peak ICP - occurs at pretty much exactly the same 40ºF rich of peak EGT as does peak CHT. Notice also the way the ICP curve parallels the CHT curve. This is why we can use CHT as a rough proxy for ICP, even though we don't have an actual ICP gauge.
Hope that helps. Sorry for the novelette. It's hard to get into this stuff without getting a bit long-winded.
Well, I was going to stay out of it, because I haven't flown a 112 Hot Shot, and don't know the equipment in the plane.
But from what I learned in the Advanced Pilots Course (APS), leaning to a "magic" TIT setting is not necessarily the best thing for your engine. So, at the risk of once again being accused of writing a novel, I'm going to address it after all...
TIT is important, because you don't want to overheat the turbo, and equally important, you don't want to overheat the exhaust pipes themselves. Burning through an exhaust pipe in a turbo-charged airplane is high on my list of things to avoid!
But TIT is NOT a substitute for all-cylinder EGT readings for leaning an aircraft engine. Leaning by TIT would "assume" that all the cylinders reach their peak EGTs (the measure of their individual mixture settings) at the same mixture adjustment where peak TIT was recorded.
In fact, our aircraft engines have notoriously bad intake and distribution designs that practically guarantee that each cylinder receives a different volume of fuel and air than does any other cylinder. The APS folks describe our aircraft engines as a collection of single-cylinder engines driving a common crankshaft.
Why does that matter? Well, the main thing is that at any given mixture control position, every cylinder's "actual" mixture is slightly different, meaning that one cylinder is leaner than all the others and one cylinder is richer than all the others. That spread can be significant - especially in carbureted engines, which create even wider disparity in cylinder mixtures... But fuel-injected engines aren't immune from this, either. Most "factory" injected engines will have a GAMI Spread (measured by the GAMI Lean Test) of somewhere between 1.0 gph and 2.0 gph. Some are better than that, and some can be even worse. (As a side note, GAMI sells flow-matched fuel injectors which should bring your fuel-injected engine's GAMI Spread down to 0.5 gph or better, which results in a much smoother engine under all circumstances. This is particularly important if you want to operate LOP with a nice, smooth engine.)
Anyway, with a substantial difference between each individual cylinder's "actual" mixture condition, a single-point TIT reading is NOT going to tell you where your engine (meaning the entire collection of those individual single-cylinder engines) is operating on the continuum from ROP to PEAK to LOP. It's going to give you an "averaged" result that is better than a single-cylinder EGT gauge (as the factory delivered them), but nowhere near as accurate as an "all-cylinder" engine monitor.
It makes sense that if I want to operate my engine ROP, I would want ALL the cylinders to be ROP. The reason for that is simple. When operating ROP, if my engine's CHTs reach a temperature that is unacceptable to me, the solution is to enrichen the mixture. This will drive the EGTs down, lower the Internal Combustion Pressures (ICP) in the cylinders, and in turn reduce the CHTs.
Conversely, if I want to operate LOP, I want to be darn sure that ALL the cylinders are LOP. The logic is equally simple - when operating LOP, and experiencing higher-than-desired CHTs, the solution is to lean the engine even further. I know - some of you think I'm nuts at this point, but it's true! You see, "PEAK" EGT means exactly that: the highest EGT measured by the instrument. As you add more fuel (richer mixture) to a "peak" EGT mixture, the EGT goes down. Likewise, as you reduce the fuel (leaner mixture) from that "peak" EGT mixture, the EGT will likewise go down.
But since this isn't a ROP vs LOP discussion, let's table the LOP discussion, and get back to the "book" procedures. After all, Lycoming says LOP operations are "prohibited" (other than briefly while leaning to find the peak EGT values).
So, if I lean by TIT, I'm almost guaranteed that at least one cylinder will be ROP and at least one cylinder will be LOP. If my GAMI Spread is within that 1.0-2.0 range, when I enrichen TIT to 100ºF above peak TIT, I am almost guaranteed to have one of my leanest cylinders wind up with a mixture that is right about at 40ºF ROP. Why is that a bad thing? Well, it just so happens that 40ºF ROP is precisely where ICP (and CHT, which parallels ICP as mixture changes) reaches its peak value. So now I'm operating my engine where one (or more) cylinders are almost guaranteed to be at their highest operating CHT... And high CHTs are not a good thing for engine longevity.
By leaning your engine with an all-cylinder engine monitor, you can observe ALL of the cylinders, and note when the FIRST one reaches peak EGT reading. And THAT is the starting point for ROP operations. Now I can realistically decide "Do I want to operate at Best Power or Best Economy for this flight?"
If Best Power is my goal, Lycoming says to adjust the mixture so that the leanest cylinder (the first to reach peak EGT as you lean the engine) is 100ºF lower (on the rich side) of its peak EGT reading. The APS folks would recommend that if you're truly wanting to go as fast as possible, and operating at "Best Power" (75%), you should adjust the mixture to more like 150-200ºF ROP.
If Best Economy is my goal, Lycoming says to adjust the mixture so that leanest cylinder is at the peak EGT reading. While Lycoming doesn't address the reason for this, it is technically the closest they can get you to the point of maximum fuel efficiency without operating LOP. The APS folks would suggest that if Economy is the goal and you are restricting yourself to ROP operations, you should operate at 60% power (or less) and with a mixture adjusted to peak EGT.
I'm attaching the "Landmarks.pdf" file to this post. It graphically depicts the four items I talked about in the post (EGT, CHT, ICP, and HP), along with one I didn't really discuss (1/BSFC, which is the inverse of Brake Specific Fuel Consumption). That last one is a measure of fuel efficiency. The chart is set up so that all the values are plotted as you go from Rich (left side of the chart) to Lean (right of the chart)
The five "Landmarks" on that chart are as follows:
1) the point where EGT is at its highest value (Peak EGT). Note that EGTs go down both to the left (richer) and to the right (leaner).
2) Peak CHT - occurs at approximately 40ºF rich of peak EGT
3) Peak HP (maximum power output) - occurs at approximately 80ºF rich of peak EGT
4) Peak Efficiency - occurs between 40-70ºF lean of peak EGT. Note that if you ignore the LOP side of the chart (everything to the right of the dotted black line), best efficiency would occur at peak EGT.
5) Peak ICP - occurs at pretty much exactly the same 40ºF rich of peak EGT as does peak CHT. Notice also the way the ICP curve parallels the CHT curve. This is why we can use CHT as a rough proxy for ICP, even though we don't have an actual ICP gauge.
Hope that helps. Sorry for the novelette. It's hard to get into this stuff without getting a bit long-winded.
nruzic
New member
Hampton, VA
- Aircraft Year
- 1992
- Aircraft Type
- 114B/115
- Reg Number
- N114PW
- Serial Number
- 14542
Re: Tit
Jim no need to apologize for being long winded you only need to apologize if you're hot winded (no Scott not saying anything about your posts).
Thanks for the attached pdf but even more for your clear summary of the subject.
Question about the attached - what are the 2 traces numbered 4?
Is the Brown Solid trace a consistent Rich Mixture & the Dotted trace a consistent Lean Mixture?
I wonder if they put actual numbers on this trace.
As far as I know the best measured numbers for BSFC were on a dual turbo TSIO 550 Malibu where its about 0.36 lb/hr per HP LOP in cruise under 65%.
The IO 540 I think would be about 0.42 lb/hr per HP. Typically the IO 540 cruise @ 65% above 5000ft Std Atmosphere @ 13gph would be around 0.5 65% cruise is 169HP so 169/13 = 13 HP per gph or 13HP per 6lb/hr so the reciprocal of 13/7 give BSFC of 0.46 lb/hr per HP. Now if you lean further to Peak perhaps you would reach BSFC of 0.43 b/hr per HP.
Looking at the 13gph cruise another way means you're burning fuel energy of about 18000x6x13 = 1.4 M BTU/hr OR 353 M Cal/hr.
Alas under 30% of this energy is converted into mechanical energy.
Jim no need to apologize for being long winded you only need to apologize if you're hot winded (no Scott not saying anything about your posts).
Thanks for the attached pdf but even more for your clear summary of the subject.
Question about the attached - what are the 2 traces numbered 4?
Is the Brown Solid trace a consistent Rich Mixture & the Dotted trace a consistent Lean Mixture?
I wonder if they put actual numbers on this trace.
As far as I know the best measured numbers for BSFC were on a dual turbo TSIO 550 Malibu where its about 0.36 lb/hr per HP LOP in cruise under 65%.
The IO 540 I think would be about 0.42 lb/hr per HP. Typically the IO 540 cruise @ 65% above 5000ft Std Atmosphere @ 13gph would be around 0.5 65% cruise is 169HP so 169/13 = 13 HP per gph or 13HP per 6lb/hr so the reciprocal of 13/7 give BSFC of 0.46 lb/hr per HP. Now if you lean further to Peak perhaps you would reach BSFC of 0.43 b/hr per HP.
Looking at the 13gph cruise another way means you're burning fuel energy of about 18000x6x13 = 1.4 M BTU/hr OR 353 M Cal/hr.
Alas under 30% of this energy is converted into mechanical energy.
JimParker256
New member
McKinney, TX
- Aircraft Year
- 1965 Champion 7ECA
- Aircraft Type
- Other
- Reg Number
- N9502S
- Serial Number
- 243
Re: Tit
Sid,
This "Landmarks" diagram is pretty "generic" with no specific numbers on it for a reason. It's used to teach the relationships between the various landmarks, rather than the specifics of any engine, power setting, etc. Those relationships hold true for anything from an A-65 all the way up to double- and triple-row radial engines producing thousands of horsepower. But obviously, the specific measurements will vary significantly with power settings, etc. Yet the "curves" are remarkably consistent from engine to engine... Pretty interesting stuff.
As for the brown traces, they represent the relative fuel efficiency of a very rich mixture (far left side), and a very lean mixture (far right side), and everything in between. If I remember correctly, the solid brown trace is for fuel-injected engines, and the dashed trace for carbureted engines, but I'll have to verify that to be sure. I'll double-check with the author and post the result later today, but right now, I'm walking out the door to drive 100 miles to pick up my airplane from the A&P/IA who did the annual, and fly it home. Good times!
Sid,
This "Landmarks" diagram is pretty "generic" with no specific numbers on it for a reason. It's used to teach the relationships between the various landmarks, rather than the specifics of any engine, power setting, etc. Those relationships hold true for anything from an A-65 all the way up to double- and triple-row radial engines producing thousands of horsepower. But obviously, the specific measurements will vary significantly with power settings, etc. Yet the "curves" are remarkably consistent from engine to engine... Pretty interesting stuff.
As for the brown traces, they represent the relative fuel efficiency of a very rich mixture (far left side), and a very lean mixture (far right side), and everything in between. If I remember correctly, the solid brown trace is for fuel-injected engines, and the dashed trace for carbureted engines, but I'll have to verify that to be sure. I'll double-check with the author and post the result later today, but right now, I'm walking out the door to drive 100 miles to pick up my airplane from the A&P/IA who did the annual, and fly it home. Good times!
Nr. Albany, GA
- Aircraft Year
- 1974
- Aircraft Type
- 112 Hot Shot
- Reg Number
- N1182J
- Serial Number
- 155
Re: Tit
I think that I will just accept 25 less hours between overhaul than to read and try and understand all that information.
It would be interesting to survey engine life for those folks with an engine monitor and those folks without one. I could get one of those fancy watches that hooks up to my I-phone. Then blue tooth it to my I-pad mounted on the yoke.
As I lean the engine I could watch my blood pressure, pulse rate and blood oxygen and see it there is any correlation. For the Commander to fly it does require input from the pilot and so many of us are over TBO
Life is a barrel of fun.
I think that I will just accept 25 less hours between overhaul than to read and try and understand all that information.
It would be interesting to survey engine life for those folks with an engine monitor and those folks without one. I could get one of those fancy watches that hooks up to my I-phone. Then blue tooth it to my I-pad mounted on the yoke.
As I lean the engine I could watch my blood pressure, pulse rate and blood oxygen and see it there is any correlation. For the Commander to fly it does require input from the pilot and so many of us are over TBO
Life is a barrel of fun.
nruzic
New member
Hampton, VA
- Aircraft Year
- 1992
- Aircraft Type
- 114B/115
- Reg Number
- N114PW
- Serial Number
- 14542
Re: Tit
Ken granted everyone needn't get into all these details.
It's useful to know the engine trends & what happens when we lean in cruise.
Certainly for the aficionados there's pleasure in squeezing the last calories of energy out of every drop of fuel and for the sheer fun of it as we barrel along to borrow your phrase.
Ken granted everyone needn't get into all these details.
It's useful to know the engine trends & what happens when we lean in cruise.
Certainly for the aficionados there's pleasure in squeezing the last calories of energy out of every drop of fuel and for the sheer fun of it as we barrel along to borrow your phrase.