TSIO 360 leaning questions.
Thread Starter
TSIO 360 leaning questions.
In the past, the engines that I have run LOP have not had LOP prohibited by the engine operators manual. Using the Deakin / APS leaning techniques were not in conflict with the engine operators manual.
However, the CMI TSIO360 engine operators manual specifically prohibits LOP operation. Yet, anecdotally many Seneca II, Mooney 231 and Tirbo Arrow drivers run LOP successfully. I hoping for a comment by Jaba or JD or Walter on this.
Also, there is a thread on the Beechtalk forum about leaning solely according to TIT where George Brayley says that leaning according to TIT is fine and that EGT's are not that important for leaning of turbocharhed engines. However an APS branded seminar delivered to the EAA (by I think Mike Busch - available on the EAA website) condemned leaning by TIT. I can't see any reason why you wouldn't lean by TIT. Surely TIT and EGT have a direct relationship? The numbers might be different, but the curves should be the same shape?
My third question is leaning in the climb. The engine operators manual and the POH say to climb full rich. This is a pretty frightening fuel flow rate. I assume this is for cylinder cooling. But, I climb at 75% power and Carson speed (117 kts for the Seneca) not Best rate speed (89 kts). So, can I lean to best power settings as long as the CHT is within limits?
Out of curiosity, I overlaid the mixture / power graphs of the TSIO 360 and its normally aspirated brother. I was surprised at how different all 3 curves are (best econ, best power and full rich). Best economy and best power are not too different below about 80% power (the TSIO version uses a bit more), but full rich figure is about 50% higher. Is this just to provide fuel cooling? And shouldn't the turbo version be more efficient?
However, the CMI TSIO360 engine operators manual specifically prohibits LOP operation. Yet, anecdotally many Seneca II, Mooney 231 and Tirbo Arrow drivers run LOP successfully. I hoping for a comment by Jaba or JD or Walter on this.
Also, there is a thread on the Beechtalk forum about leaning solely according to TIT where George Brayley says that leaning according to TIT is fine and that EGT's are not that important for leaning of turbocharhed engines. However an APS branded seminar delivered to the EAA (by I think Mike Busch - available on the EAA website) condemned leaning by TIT. I can't see any reason why you wouldn't lean by TIT. Surely TIT and EGT have a direct relationship? The numbers might be different, but the curves should be the same shape?
My third question is leaning in the climb. The engine operators manual and the POH say to climb full rich. This is a pretty frightening fuel flow rate. I assume this is for cylinder cooling. But, I climb at 75% power and Carson speed (117 kts for the Seneca) not Best rate speed (89 kts). So, can I lean to best power settings as long as the CHT is within limits?
Out of curiosity, I overlaid the mixture / power graphs of the TSIO 360 and its normally aspirated brother. I was surprised at how different all 3 curves are (best econ, best power and full rich). Best economy and best power are not too different below about 80% power (the TSIO version uses a bit more), but full rich figure is about 50% higher. Is this just to provide fuel cooling? And shouldn't the turbo version be more efficient?
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Akro,
Send me a scanned or PDF of your POH first of all.
Second,
I highly doubt that would or could ever happen. It may be theoretically possible, but not likely.
Q3 well if you climb full rated power, full rich is the go. If you de-rate the climb power adjust the fuel flow accordingly.
As for the difference in fuel flow, two reasons. First for high powers the detonation margin and IAT/CDT requires a bit more, secondly the compression ratio of the TC is lower thus the fuel used per HP is always going to be higher, all things otherwise being equal.
Send me the POH, we can talk later.
And I will post back later too, or JD or WA might drop in. I am setting up for APS class in Perth......if you are quick......
Send me a scanned or PDF of your POH first of all.
Second,
However an APS branded seminar delivered to the EAA (by I think Mike Busch - available on the EAA website) condemned leaning by TIT.
Q3 well if you climb full rated power, full rich is the go. If you de-rate the climb power adjust the fuel flow accordingly.
As for the difference in fuel flow, two reasons. First for high powers the detonation margin and IAT/CDT requires a bit more, secondly the compression ratio of the TC is lower thus the fuel used per HP is always going to be higher, all things otherwise being equal.
Send me the POH, we can talk later.
And I will post back later too, or JD or WA might drop in. I am setting up for APS class in Perth......if you are quick......
Thread Starter
Jaba
This is the EAA video, but I wrongly remembered one of the logos, so I may have done you a dis-service. Because its branded Savvy Aviator, I'm presuming its Mike Busch.
EAA Video Player - Your Source for Aviation Videos
I think I have a pdf copy of the engine operators manual. I'll email it. Enjoy Perth.
This is the EAA video, but I wrongly remembered one of the logos, so I may have done you a dis-service. Because its branded Savvy Aviator, I'm presuming its Mike Busch.
EAA Video Player - Your Source for Aviation Videos
I think I have a pdf copy of the engine operators manual. I'll email it. Enjoy Perth.
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TSIO 360 Leaning Questions
Old Akro,
First, let me gently take issue your "Deakin / APS" comment. While I love the attribution, and I wish I could take credit, t'ain't so. Nor is it an "APS method" as we didn't invent it. The method has been described in the literature since as far back as Lindbergh's flight across the Atlantic. (I know you know this, but for historical purposes I feel compelled to mention it.)
Post WWII, the airlines re-discovered it, and put it to good use, as well described in "BASIC THEORY OF OPERATION," a 32-page booklet given to all pilots, flight engineers, and mechanics at American Airlines, along with very clear MANDATES similar to "YOU WILL OPERATE THIS WAY." Other airlines and the military got the idea, and the result was about 400,000,000 engine hours of operation on the R-3350 and R-2800. That was directly responsible for those engines going from a TBO of about 400 hours, to 3,600 hours. It was still improving when those wonderful engines were rudely knocked out by the jets, with their stinky fuel and awful screech.
But those engines had BMEP instrumentation, which shows the crew TORQUE directly (with a simple conversion to BHP) in real time. Move any lever (Throttle, Prop, Mixture, Carb Heat) and watch the BMEP needle move right along with it.
We lost that with the "flat" engines, for there is no "Nose Case Reduction Gearing" with the big "floating" ring gear of a big radial, not even on the geared flat engines. Additionally, there are lubrication issues on the Radials that don't apply to "flats," but otherwise, the parts of the engine that are involved in THE COMBUSTION EVENT use the same principles, the same metallurgy and the same processes. For that matter, they are identical in all four-stroke, gasoline engines.
Really? Does it say, "NO LOP OPERATION" in the LIMITATIONS section? It would be the first time I've ever seen that in any manual. There ARE POHs that say very specifically, "DO NOT CRUISE ROP," which would be the way to do it, if that's the intent.
What happened here is that the engine manufacturers and the industry discovered very early on that the "flat" engines will simply not run LOP, they shake too much! EVERYONE thought it due to an imbalance of AIR! Instead of fixing the problem, they stuck various notes into the documentation, with varying language from "Cabin Comfort" to "Undesirable Roughness," and over the decades it became accepted, and the lean side of the power curves were forgotten, and became "THE FORBIDDEN ZONE."
It's laughable now, but it took George Braly to discover it was THE FUEL that was unbalanced, and to develop the solution, which opened up the entire chart, and others had developed the "Engine Monitor," which made it clear to the average pilot. But we've still got those engine manuals first written in the forties, fifties and later with the original waffle-language, which will never go away. CASA making any claim otherwise simply makes them idiots.
That they do, and you fine folks must follow their idiotic rules is beyond reasoning, and I cannot address it.
Absolutely true. It has the additional advantage of keeping you out of trouble with TIT limits, which are far more important than EGT, which have NO LIMITS (except for malfunctions.)
As pointed out, there is no connection between APS and Savvy. I've known Mike for more than 35 years, and normally he puts out much better than average information, but on some of it, he's simply out to lunch.
Good thinking. What's more, you're correct. 
Not on most engines, which is one area where Busch goes seriously wrong. He's a HUGE man, and the only airplane he'll fit in is his own Cessna 310q, with TSIO-520s. It's probably the only airplane he's flown. That airplane has a peculiar setup, which makes it possible to use 400℉ CHT as the limit. I think it's a wonderful airplane, but it is NOT the model to use for THIS purpose. It MAY work - for you.
But with your engine, I'd suggest you use MAX RATED POWER, as listed in the LIMITATIONs Section, not the "how to fly" textual material. If there is no time limit on TAKEOFF POWER, use it! You'll get higher (and cooler) sooner, and spend less time. The engine is good for it - at full rich. You should see EGT around 1300℉ in the climb if your engine is properly set up. Which brings us to:
Good thinking, again. It's just for cooling. And turbos are not generally more efficient, they are meant to give you more power, higher, with very little penalty in efficiency.
How big can messages be in PPrune, anyway?
Best...
John Deakin
In the past, the engines that I have run LOP have not had LOP prohibited by the engine operators manual. Using the Deakin / APS leaning techniques were not in conflict with the engine operators manual.
Post WWII, the airlines re-discovered it, and put it to good use, as well described in "BASIC THEORY OF OPERATION," a 32-page booklet given to all pilots, flight engineers, and mechanics at American Airlines, along with very clear MANDATES similar to "YOU WILL OPERATE THIS WAY." Other airlines and the military got the idea, and the result was about 400,000,000 engine hours of operation on the R-3350 and R-2800. That was directly responsible for those engines going from a TBO of about 400 hours, to 3,600 hours. It was still improving when those wonderful engines were rudely knocked out by the jets, with their stinky fuel and awful screech.
But those engines had BMEP instrumentation, which shows the crew TORQUE directly (with a simple conversion to BHP) in real time. Move any lever (Throttle, Prop, Mixture, Carb Heat) and watch the BMEP needle move right along with it.
We lost that with the "flat" engines, for there is no "Nose Case Reduction Gearing" with the big "floating" ring gear of a big radial, not even on the geared flat engines. Additionally, there are lubrication issues on the Radials that don't apply to "flats," but otherwise, the parts of the engine that are involved in THE COMBUSTION EVENT use the same principles, the same metallurgy and the same processes. For that matter, they are identical in all four-stroke, gasoline engines.
However, the CMI TSIO360 engine operators manual specifically prohibits LOP operation.
What happened here is that the engine manufacturers and the industry discovered very early on that the "flat" engines will simply not run LOP, they shake too much! EVERYONE thought it due to an imbalance of AIR! Instead of fixing the problem, they stuck various notes into the documentation, with varying language from "Cabin Comfort" to "Undesirable Roughness," and over the decades it became accepted, and the lean side of the power curves were forgotten, and became "THE FORBIDDEN ZONE."
It's laughable now, but it took George Braly to discover it was THE FUEL that was unbalanced, and to develop the solution, which opened up the entire chart, and others had developed the "Engine Monitor," which made it clear to the average pilot. But we've still got those engine manuals first written in the forties, fifties and later with the original waffle-language, which will never go away. CASA making any claim otherwise simply makes them idiots.
That they do, and you fine folks must follow their idiotic rules is beyond reasoning, and I cannot address it.
Also, there is a thread on the Beechtalk forum about leaning solely according to TIT where George Braly says that leaning according to TIT is fine and that EGT's are not that important for leaning of turbocharhed engines.
However an APS branded seminar delivered to the EAA (by I think Mike Busch - available on the EAA website) condemned leaning by TIT.
I can't see any reason why you wouldn't lean by TIT. Surely TIT and EGT have a direct relationship? The numbers might be different, but the curves should be the same shape?
My third question is leaning in the climb. The engine operators manual and the POH say to climb full rich. This is a pretty frightening fuel flow rate. I assume this is for cylinder cooling. But, I climb at 75% power and Carson speed (117 kts for the Seneca) not Best rate speed (89 kts). So, can I lean to best power settings as long as the CHT is within limits?
But with your engine, I'd suggest you use MAX RATED POWER, as listed in the LIMITATIONs Section, not the "how to fly" textual material. If there is no time limit on TAKEOFF POWER, use it! You'll get higher (and cooler) sooner, and spend less time. The engine is good for it - at full rich. You should see EGT around 1300℉ in the climb if your engine is properly set up. Which brings us to:
Out of curiosity, I overlaid the mixture / power graphs of the TSIO 360 and its normally aspirated brother. I was surprised at how different all 3 curves are (best econ, best power and full rich). Best economy and best power are not too different below about 80% power (the TSIO version uses a bit more), but full rich figure is about 50% higher. Is this just to provide fuel cooling? And shouldn't the turbo version be more efficient?
How big can messages be in PPrune, anyway?
Best...
John Deakin
Thread Starter
John
Thanks for the reply. I appreciate the effort.
Firstly, let me repeat my apology for mis-attributing the EAA presentation to APS. Its what happens when I work from memory.
Next, one of my trivial issues relates to the efficiency of Turbo's. If they aren't more efficient why do basically all modern European engines use them? They should be getting benefit from entropy. In my comments about the TSIO 360 vs the IO 360 I forgot the compression ratio difference. The IO 360 will have greater thermodynamic efficiency because of the higher compression ratio, but I would have thought that the better volumetric efficiency of the turbo - especially with such a crappy inlet manifold - would have more than compensated.
I understand your point about climbing at full power, but I'm having trouble getting over decades of habit. And I'm re-reading your article " Those fire breathing turbo's - part 4" . This article relates to the turbo normalised automatic waste gate TSIO 550. But the TSIO 360 generates so little boost that it can nearly be regarded as turbo normalised (the boost is certainly kidstuff compared with automotive turbo's). And it has a fixed wastegate - which really just means I have to do more work with the levers. Most of the time the engine operates with about atmospheric manifiold pressure (ie 28 - 32 inches). The TSIO 550 & 360 also seem to share the same design building blocks - although I make this assessment without much facts.
Back to the climb. Your article suggests WOT, which I can't do and remain below the 40 inch limit. But the TSIO is rated for continuous power at 40 inches, so I can run at that. You advocate full fine, but (like the your preference in the Bo) I prefer to run 2400 or 2500 rather than full fine (2575). It just feels less hectic.
If I climb at 40 inches and 2500 rpm, (from memory) I think the fuel flows will be above the "full rich" line in the engine operators manual. If I reduce mixture a little (once again from memory) I think the TIT will be maybe as low as 1100. In your article you are suggesting leaning to 1290 TIT below 10,000 ft. So, with the caveat of CHT limits, can I lean further to 1290 TIT?
I can generally climb with lower CHT than I get in cruise (especially in the flight levels). I don't expect CHT to be much of an issue.
Both Piper and CMI list 75% (31.5 / 2474) power as maximum recommended climb power, while 100% power (40 / 2575) is a continuous rating.
I'm a fan of Carson speeds. So I'd like to climb at 117 - 120 kIAS, not the best rate 89 KIAS or the Piper suggested 102 KIAS cruise climb. Once I've got the airplane cleaned up and sorted, 75% gives me a fairly solid 500 fpm through to the flight levels, which I've thought was good enough.
Now we get to the cruise.
Based on Carson's work, about 60% power should be optimal for the Seneca cruise. But, I'm growing to like the speed of about 65%. So far, I see bugger all actual fuel flow difference between 60 & 65%, but I do see a speed difference. For me this will typically be about 28 / 2400 at 8 - 10,000 ft. The 3 blade props seem to like 2400 rpm.
The Piper POH Normal Procedures section refers to the engine operators book for leaning. The CMI OM says to lean according to the power table & fuel flow figures. I truly find this bizzare.
But, the fuel flow / power graph that we are supposed to use as a leaning reference says:
" Continuous operation at fuel flows leaner than 25degF rich of peak TIT is prohibited for all conditions"
I know you will talk about the only mandatory part of the POH being the limitations section, but that is a pretty explicit statement.
In previous aircraft I have flown (mainly IO-540's) I can run a LOP regime that you would approve of (did you notice I avoided saying APS method?), without being in conflict with the engine operators manual. I don't like being in direct conflict with the engine operators manual.
So, I typically cruise at 65% power and 25 degF ROP. Its not what you teach, but at that power setting its not going to hurt and its consistent with the book. Typically this is about 1575 - 1625 TIT depending on the day. Frequently I find peak is about 1650 TIT (maybe 1625 - 1675). But, it uses a lot more fuel than it ought and has higher fuel rates than the CMI best economy table. I have a suspicion that the best economy table might actually be LOP, but CMI aren't admitting it.
In part I'm looking for courage to try "the big pull" and get to maybe 50 TIT LOP.
The TSIO 360 is a relatively uncommon engine that frequently has service difficulties and is typically excluded from the general advice articles. So, I'm being tentative.
Thanks for your interest in helping.
Thanks for the reply. I appreciate the effort.
Firstly, let me repeat my apology for mis-attributing the EAA presentation to APS. Its what happens when I work from memory.
Next, one of my trivial issues relates to the efficiency of Turbo's. If they aren't more efficient why do basically all modern European engines use them? They should be getting benefit from entropy. In my comments about the TSIO 360 vs the IO 360 I forgot the compression ratio difference. The IO 360 will have greater thermodynamic efficiency because of the higher compression ratio, but I would have thought that the better volumetric efficiency of the turbo - especially with such a crappy inlet manifold - would have more than compensated.
I understand your point about climbing at full power, but I'm having trouble getting over decades of habit. And I'm re-reading your article " Those fire breathing turbo's - part 4" . This article relates to the turbo normalised automatic waste gate TSIO 550. But the TSIO 360 generates so little boost that it can nearly be regarded as turbo normalised (the boost is certainly kidstuff compared with automotive turbo's). And it has a fixed wastegate - which really just means I have to do more work with the levers. Most of the time the engine operates with about atmospheric manifiold pressure (ie 28 - 32 inches). The TSIO 550 & 360 also seem to share the same design building blocks - although I make this assessment without much facts.
Back to the climb. Your article suggests WOT, which I can't do and remain below the 40 inch limit. But the TSIO is rated for continuous power at 40 inches, so I can run at that. You advocate full fine, but (like the your preference in the Bo) I prefer to run 2400 or 2500 rather than full fine (2575). It just feels less hectic.
If I climb at 40 inches and 2500 rpm, (from memory) I think the fuel flows will be above the "full rich" line in the engine operators manual. If I reduce mixture a little (once again from memory) I think the TIT will be maybe as low as 1100. In your article you are suggesting leaning to 1290 TIT below 10,000 ft. So, with the caveat of CHT limits, can I lean further to 1290 TIT?
I can generally climb with lower CHT than I get in cruise (especially in the flight levels). I don't expect CHT to be much of an issue.
Both Piper and CMI list 75% (31.5 / 2474) power as maximum recommended climb power, while 100% power (40 / 2575) is a continuous rating.
I'm a fan of Carson speeds. So I'd like to climb at 117 - 120 kIAS, not the best rate 89 KIAS or the Piper suggested 102 KIAS cruise climb. Once I've got the airplane cleaned up and sorted, 75% gives me a fairly solid 500 fpm through to the flight levels, which I've thought was good enough.
Now we get to the cruise.
Based on Carson's work, about 60% power should be optimal for the Seneca cruise. But, I'm growing to like the speed of about 65%. So far, I see bugger all actual fuel flow difference between 60 & 65%, but I do see a speed difference. For me this will typically be about 28 / 2400 at 8 - 10,000 ft. The 3 blade props seem to like 2400 rpm.
The Piper POH Normal Procedures section refers to the engine operators book for leaning. The CMI OM says to lean according to the power table & fuel flow figures. I truly find this bizzare.
But, the fuel flow / power graph that we are supposed to use as a leaning reference says:
" Continuous operation at fuel flows leaner than 25degF rich of peak TIT is prohibited for all conditions"
I know you will talk about the only mandatory part of the POH being the limitations section, but that is a pretty explicit statement.
In previous aircraft I have flown (mainly IO-540's) I can run a LOP regime that you would approve of (did you notice I avoided saying APS method?), without being in conflict with the engine operators manual. I don't like being in direct conflict with the engine operators manual.
So, I typically cruise at 65% power and 25 degF ROP. Its not what you teach, but at that power setting its not going to hurt and its consistent with the book. Typically this is about 1575 - 1625 TIT depending on the day. Frequently I find peak is about 1650 TIT (maybe 1625 - 1675). But, it uses a lot more fuel than it ought and has higher fuel rates than the CMI best economy table. I have a suspicion that the best economy table might actually be LOP, but CMI aren't admitting it.
In part I'm looking for courage to try "the big pull" and get to maybe 50 TIT LOP.
The TSIO 360 is a relatively uncommon engine that frequently has service difficulties and is typically excluded from the general advice articles. So, I'm being tentative.
Thanks for your interest in helping.
Last edited by Old Akro; 17th May 2014 at 02:39.
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Very interesting...
Keep this one going... I am watching this one carefully! I am a little shocked to see how differently my Seneca (III, TSIO-360KB) runs compared to OA's...
I climb, full rich, at 35/25, at 117kts (thanks for that mate!) and get about 500-700 fpm well into the FLs, and never trouble the CHT's above about 300.
When are you heading to Sydney next, OA?
I climb, full rich, at 35/25, at 117kts (thanks for that mate!) and get about 500-700 fpm well into the FLs, and never trouble the CHT's above about 300.
When are you heading to Sydney next, OA?
Not sure how uncommon you'd call the TSIO 360, there was about 2500 turbo Seneca produced from the Seneca II onwards, plus all the single engine turbo aircraft variations that have used it. I've found the operational problems with them have revolved around the installation especially ancillaries. The Seneca II with EB was pretty good, the Seneca V with the RB was horrible, the III and IV were ok. The V also had density controllers and other nice automatic controls for the turbo, I think the latter IVs had this as well.
We used a 110kt climb in the V, and the earlier models the 100-105 got you up nice and quickly, 117kt sounds like it would work well.
I'd be interested to see what fuel burns vs speed you could get from a Seneca II with LOP ops. These were very misunderstood aircraft that could offer a very cheap twin both in purchase and operating cost. The two blade one we had was light, could carry 5 adults with bags and cruised around 170ktas at about 65%. I don't think the 3 blades, like the Seminole ones had any benefit due to the low power output, the III onward had more power with 220hp so it was more justified.
When we operated the Vs the engineers didn't like the recommended procedure of leaning to peak and requested we lean 100' ROP.
We used a 110kt climb in the V, and the earlier models the 100-105 got you up nice and quickly, 117kt sounds like it would work well.
I'd be interested to see what fuel burns vs speed you could get from a Seneca II with LOP ops. These were very misunderstood aircraft that could offer a very cheap twin both in purchase and operating cost. The two blade one we had was light, could carry 5 adults with bags and cruised around 170ktas at about 65%. I don't think the 3 blades, like the Seminole ones had any benefit due to the low power output, the III onward had more power with 220hp so it was more justified.
When we operated the Vs the engineers didn't like the recommended procedure of leaning to peak and requested we lean 100' ROP.
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Old Akro:
1) We do not recommend WOT for the climb on the TC'd engines. Only the TN and NA engines. We recommend that you use the top of the green MP as outlined in the POH for your aircraft and climb full rich. The 1300dF target is for non-TC'd engines. Your engine's Target should be around 1150-1200dF, so you;r not very far off as it is. Were I flying your aircraft and wanting to treat it kindly, i would leave it full rich at the climb power setting.
2) Using the max RPM is easier on the engine than a reduced RPM. The thetaPP is later and the peak pressures are lower at higher RPMs… all good things. The differences between 2700 and 2500 are small, so I do agree that it is a minor issue.
3) Cruise is a different matter. The POH recommendations to limit cruise power are based on being ROP and they make sense in that condition. If one operates LOP in cruise much higher power settings are fine since they result in lower peak pressures, wider detonation margins (not really a factor) and cooler CHTs. All of these are positive factors along with the cleaner running combustion chamber.
4) "Continuous operation at fuel flows leaner than 25degF rich of peak TIT is prohibited for all conditions" is a good recommendation for ROP back when everyone ran ROP only. It does not apply to LOP.
5) 25dF ROP is the mixture where the exhaust valves run the hottest. If that's your objective, then that's your mixture!
1) We do not recommend WOT for the climb on the TC'd engines. Only the TN and NA engines. We recommend that you use the top of the green MP as outlined in the POH for your aircraft and climb full rich. The 1300dF target is for non-TC'd engines. Your engine's Target should be around 1150-1200dF, so you;r not very far off as it is. Were I flying your aircraft and wanting to treat it kindly, i would leave it full rich at the climb power setting.
2) Using the max RPM is easier on the engine than a reduced RPM. The thetaPP is later and the peak pressures are lower at higher RPMs… all good things. The differences between 2700 and 2500 are small, so I do agree that it is a minor issue.
3) Cruise is a different matter. The POH recommendations to limit cruise power are based on being ROP and they make sense in that condition. If one operates LOP in cruise much higher power settings are fine since they result in lower peak pressures, wider detonation margins (not really a factor) and cooler CHTs. All of these are positive factors along with the cleaner running combustion chamber.
4) "Continuous operation at fuel flows leaner than 25degF rich of peak TIT is prohibited for all conditions" is a good recommendation for ROP back when everyone ran ROP only. It does not apply to LOP.
5) 25dF ROP is the mixture where the exhaust valves run the hottest. If that's your objective, then that's your mixture!
Thread Starter
Walter. Thankyou. I think the time you & John put into responding is fantastic.
But, inevitably, I have more questions:
1.
John Deaking article " Those Fore Breathing Turbo's - part 4" which is Pelican's perch #34 says:
He goes on to make further references to leaning the TSIO 550 by reference to TIT. This is where I got both the idea and the numbers, so please explain.
Part of my problem, is that there are a number of versions of full rich for the TSIO 360. This is why I am looking for a better reference. The variations I have are:
1. Actual full rich on the aircraft. This frequently has higher fuel flows that the "Max Allowable - full rich" line on the fuel flow vs BHP graph in the CMI OM
2. Full rich as defined by the " Max allowable - full rich" line on the fuel flow vs BHP graph in the CMI OM. I will need to lean to get to this figure.
3. Rich by TIT - any guideline of climbing by TIT (even your suggested 1100 - 1200) will require a degree of leaning.
If I look at the fuel flow vs BHP graph for the TSIO 360 - KB engine of the Seneca III as a proxy then I get 2 more full rich figures;
4. "Recommended Full Rich" when I overlay the TSIO 360 EB graph, this is a higher fuel flow than " Max allowable - full rich" for that engine.
5. The TSIO 360 KB engine has an additional line labelled " Approximate Full rich"
At 200 Hp (40 / 2575) these 5 different " full rich" conditions show a variation of about 10 litres / hr (about 11%).
I will check later today, but from memory the procedure to set fuel pressure is the same for all variations of the TSIO 360, which makes the variation in the full rich curve between engines as more curious.
I also find it curious that " full rich" changes across the TSIO-360 series. At 200 Hp it varies from the TSIO 360 AB at 110 lbs/hr to the TSIO 360 EB at 140 lbs/hr. This makes me think that " full rich" is a notional concept.
At the CMI Recommended climb power of 75% (150 Hp) the difference between these full rich figures is 14 litres per hour - or about 25%.
But, inevitably, I have more questions:
1.
The 1300dF target is for non-TC'd engines. Your engine's Target should be around 1150-1200dF, so your not very far off as it is
TATurbo says, for climb, rich of peak EGT (ROP), with their turbo installation, use the mixture, and:
Below 10,000 feet MSL, adjust the Turbine Inlet Temperature (TIT) to about 1290°F.
Above 10,000 feet MSL, adjust the TIT to about 1270°F.
Above 17,000 feet MSL, adjust the TIT to about 1250°F
Below 10,000 feet MSL, adjust the Turbine Inlet Temperature (TIT) to about 1290°F.
Above 10,000 feet MSL, adjust the TIT to about 1270°F.
Above 17,000 feet MSL, adjust the TIT to about 1250°F
In fact, I suspect that pilots could just use 1250°F during ROP climbs, with very little "cost."
This concept of a "Target TIT" works very well in a very wide variety of turbocharged engines, not just the normalized versions.
Part of my problem, is that there are a number of versions of full rich for the TSIO 360. This is why I am looking for a better reference. The variations I have are:
1. Actual full rich on the aircraft. This frequently has higher fuel flows that the "Max Allowable - full rich" line on the fuel flow vs BHP graph in the CMI OM
2. Full rich as defined by the " Max allowable - full rich" line on the fuel flow vs BHP graph in the CMI OM. I will need to lean to get to this figure.
3. Rich by TIT - any guideline of climbing by TIT (even your suggested 1100 - 1200) will require a degree of leaning.
If I look at the fuel flow vs BHP graph for the TSIO 360 - KB engine of the Seneca III as a proxy then I get 2 more full rich figures;
4. "Recommended Full Rich" when I overlay the TSIO 360 EB graph, this is a higher fuel flow than " Max allowable - full rich" for that engine.
5. The TSIO 360 KB engine has an additional line labelled " Approximate Full rich"
At 200 Hp (40 / 2575) these 5 different " full rich" conditions show a variation of about 10 litres / hr (about 11%).
I will check later today, but from memory the procedure to set fuel pressure is the same for all variations of the TSIO 360, which makes the variation in the full rich curve between engines as more curious.
I also find it curious that " full rich" changes across the TSIO-360 series. At 200 Hp it varies from the TSIO 360 AB at 110 lbs/hr to the TSIO 360 EB at 140 lbs/hr. This makes me think that " full rich" is a notional concept.
At the CMI Recommended climb power of 75% (150 Hp) the difference between these full rich figures is 14 litres per hour - or about 25%.
Last edited by Old Akro; 18th May 2014 at 00:13.
Thread Starter
We recommend that you use the top of the green MP as outlined in the POH for your aircraft and climb full rich.
But, I like the graphs in the CMI OM - especially the older ones which are not straight lines and look like they were hand drawn from empirical data.
The TSIO 360 EB graph (which I believe is the same engine as the TSIO 360 KB, but with a lower redline RPM - 2575 rpm vs 2800 rpm) is pretty interesting when you hand draw the KB curves on the top. It looks like someone took the EB curves and made them into straight lines for the KB.
On the EB graph the fuel flow rate goes hyperbolic from about 90% power. If I run the power settings that most guys use - 35/2500 this is about 86% of the rated 200 Hp (40/2575) but has a fuel flow of 113 lb/hr vs 140 lb/hr for full power. That's a 19% reduction in fuel consumption for a 14% reduction in power.
So, wouldn't it make sense to climb at 35/2500 (86%) or 35/2575 (88%)??
Interestingly, the KB engine has a note for power settings in the range 150 Hp to 180 Hp which allows leaning to TIT 1525 degF conditional upon CHT < 420F & Oil Temp < 200F. I think this would lean the engine to the best power line, which seems too lean to me.
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Akro,
Johns article comments expressly refer to a TNIO550 or 520 with TN being the operative. The MP is 30" (+/- a bit) and not the same as your 38" so as Walter has commented, the fuel flow and BSFC is going to be much higher, and he means much higher. To have a lower compression means higher EGT, but with the much higher MP and a need to maintain a detonation margin this means a much higher fuel flow per HP, or a higher BSFC at takeoff powers.
Still in Perth, and not able to dedicate hard numbers but the fuel flow will be rather high at takeoff. I see your conundrum.
Perhaps JD or Walter will get an answer sooner but I need some sleep right now.....will study the manuals you sent me and see what we can come up with.
Johns article comments expressly refer to a TNIO550 or 520 with TN being the operative. The MP is 30" (+/- a bit) and not the same as your 38" so as Walter has commented, the fuel flow and BSFC is going to be much higher, and he means much higher. To have a lower compression means higher EGT, but with the much higher MP and a need to maintain a detonation margin this means a much higher fuel flow per HP, or a higher BSFC at takeoff powers.
Still in Perth, and not able to dedicate hard numbers but the fuel flow will be rather high at takeoff. I see your conundrum.
Perhaps JD or Walter will get an answer sooner but I need some sleep right now.....will study the manuals you sent me and see what we can come up with.
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Old Acro, et. al.:
1) John's series on "Those Fire breathing Turbos" was aimed at the TNs.
2) I made a late-night error in my post to you earlier. Your TC Target TIT should be in the 1350-1400dF range. Lower CR gives higher EGT/TIT values. That should bring your numbers closer.
Please accept my apologies for the error. Brain fart late at night.
1) John's series on "Those Fire breathing Turbos" was aimed at the TNs.
2) I made a late-night error in my post to you earlier. Your TC Target TIT should be in the 1350-1400dF range. Lower CR gives higher EGT/TIT values. That should bring your numbers closer.
Please accept my apologies for the error. Brain fart late at night.
Thread Starter
Walter, once again thanks
So, I'm planning to try this instead of my old 75% cruise climb.
35"/2575. This will be about 90% power - full fine and 5" back from the top of the green. However, it a) gives some headroom to max MP which can be easily exceeded and b) by the CMI graph puts me in a more efficient BSFC area.
I'm going to set about the CMI KB " full Rich" flow (70 litres/hr), then check the TIT and lean further to 1250 degF TIT - 1300 degF TIT (with the caveat's about CHT).
Cruise is more interesting.
I have never been able to achieve the CMI fuel flows. I have a deep suspicion that despite their "prohibition" on fuel flows leaner than 25 degF ROP TIT that in fact the economy fuel flows that they publish are maybe 25 degF LOP TIT.
This would explain why I can't get there, because I stop at 1650 degF TIT. Getting to LOP requires going though the 1650 TIT limit.
I couldn't sleep last night and was fooling around in the NASA Langley library. There is nearly nothing those guys didn't research in the seventies. Including running a TSIO 540 with hydrogen injection. UNFKNBLVBL. They hung a hydrogen generator out in the slipstream. But they made some baseline measurements on pure AVGAS that are informative.
There's also a paper on a TSIO 360 with oxygen injection to reduce exhaust emissions. But unfortunately, they only tables emissions data, not engine operating conditions.
But, particularly the Lyc TSIO 540 graphs helped me understand the behavior of TIT better. So my plan is to try 65% power and do what CMI say and lean to a fuel flow and see what happens. I think maybe it might go through peak TIT to 25 - 50 degF TIT LOP. In which case its probably a pretty good place to be.
So, I'm planning to try this instead of my old 75% cruise climb.
35"/2575. This will be about 90% power - full fine and 5" back from the top of the green. However, it a) gives some headroom to max MP which can be easily exceeded and b) by the CMI graph puts me in a more efficient BSFC area.
I'm going to set about the CMI KB " full Rich" flow (70 litres/hr), then check the TIT and lean further to 1250 degF TIT - 1300 degF TIT (with the caveat's about CHT).
Cruise is more interesting.
I have never been able to achieve the CMI fuel flows. I have a deep suspicion that despite their "prohibition" on fuel flows leaner than 25 degF ROP TIT that in fact the economy fuel flows that they publish are maybe 25 degF LOP TIT.
This would explain why I can't get there, because I stop at 1650 degF TIT. Getting to LOP requires going though the 1650 TIT limit.
I couldn't sleep last night and was fooling around in the NASA Langley library. There is nearly nothing those guys didn't research in the seventies. Including running a TSIO 540 with hydrogen injection. UNFKNBLVBL. They hung a hydrogen generator out in the slipstream. But they made some baseline measurements on pure AVGAS that are informative.
There's also a paper on a TSIO 360 with oxygen injection to reduce exhaust emissions. But unfortunately, they only tables emissions data, not engine operating conditions.
But, particularly the Lyc TSIO 540 graphs helped me understand the behavior of TIT better. So my plan is to try 65% power and do what CMI say and lean to a fuel flow and see what happens. I think maybe it might go through peak TIT to 25 - 50 degF TIT LOP. In which case its probably a pretty good place to be.
Thread Starter
This is the hydrogen injection paper, and I think I remembered wrong and they used a Duke. Titled "Ultralean combustion in General Aviation Piston Engines" dated 1979!!
http://ntrs.nasa.gov/archive/nasa/ca...9800013943.pdf
There was also another interesting paper on cooling air inlet design by Miley Owens & Lawrence
There is also a paper by Gerald Slusher of NASA which looks at exhaust gas temperatures at various locations, exhaust component temperatures and engine vibration levels. I got some interesting points about the variation of exhaust gas temperature, but I needs a serious read.
There is also some papers from Lycoming & Continental engineers that aren't available on line that I have requested.
http://ntrs.nasa.gov/archive/nasa/ca...9800013943.pdf
There was also another interesting paper on cooling air inlet design by Miley Owens & Lawrence
There is also a paper by Gerald Slusher of NASA which looks at exhaust gas temperatures at various locations, exhaust component temperatures and engine vibration levels. I got some interesting points about the variation of exhaust gas temperature, but I needs a serious read.
There is also some papers from Lycoming & Continental engineers that aren't available on line that I have requested.
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Old Acro:
**I'm going to set about the CMI KB " full Rich" flow (70 litres/hr), then check the TIT and lean further to 1250 degF TIT - 1300 degF TIT (with the caveat's about CHT). **
That should give you plenty of "head room" on the Red Box, ROP. Should work fine.
**I have never been able to achieve the CMI fuel flows. I have a deep suspicion that despite their "prohibition" on fuel flows leaner than 25 degF ROP TIT that in fact the economy fuel flows that they publish are maybe 25 degF LOP TIT.**
The POH Best Economy FFs will probably be either AT peak TIT or at 40dF LOP. If they are interested in TRUE Best Economy, it will be at 40dF LOP where the engineering graphs say it is. If they are hedging their bet about balanced F:A ratios and rough running, the number will likely be at peak. It will be interesting to find that out.
**This would explain why I can't get there, because I stop at 1650 degF TIT. Getting to LOP requires going though the 1650 TIT limit. **
The TIT limit is often misunderstood -- it is not an instantaneous limit. It is a limit for continuous ops at max rotor speed at 1650dF, which would likely only occur at critical altitude. This seldom the case, so there is a buffer built in. You can safely exceed the limit for the time it takes to find peak and reset the mixture either ROP or LOP. Most POHs list this a five-minute period.
**I'm going to set about the CMI KB " full Rich" flow (70 litres/hr), then check the TIT and lean further to 1250 degF TIT - 1300 degF TIT (with the caveat's about CHT). **
That should give you plenty of "head room" on the Red Box, ROP. Should work fine.
**I have never been able to achieve the CMI fuel flows. I have a deep suspicion that despite their "prohibition" on fuel flows leaner than 25 degF ROP TIT that in fact the economy fuel flows that they publish are maybe 25 degF LOP TIT.**
The POH Best Economy FFs will probably be either AT peak TIT or at 40dF LOP. If they are interested in TRUE Best Economy, it will be at 40dF LOP where the engineering graphs say it is. If they are hedging their bet about balanced F:A ratios and rough running, the number will likely be at peak. It will be interesting to find that out.
**This would explain why I can't get there, because I stop at 1650 degF TIT. Getting to LOP requires going though the 1650 TIT limit. **
The TIT limit is often misunderstood -- it is not an instantaneous limit. It is a limit for continuous ops at max rotor speed at 1650dF, which would likely only occur at critical altitude. This seldom the case, so there is a buffer built in. You can safely exceed the limit for the time it takes to find peak and reset the mixture either ROP or LOP. Most POHs list this a five-minute period.
Thread Starter
Thanks Walter
I'm just reading the proceedings of a symposium on piston aircraft engines from 1976. Both CMI & Lycoming did work with 80% power climbs at best power mixture settings. This regime seemed to work well, but tHeir main concern seems to be that cooling airflow is not reliably good enough. Specifically to the TSIO 360 that I'm interested in Continenta says that the engine needs 5.5 inches of water pressure drop across the engine rather than the common 4 or less.
This work seems to have been in response to a NASA sponsored project to look at emissions. More power to NASA!
The frustrating thing, us that it looks like the engineers at both Continental & Lycoming knew what to do to improve the engines, but it never happened.
I presume the product liability crisis and FAA regulatatory compliance made it too hard / too expensive.
I was also interested in another paper which experimented with what it called a " dog house" or air box which fitted on top of the engine to do away with baffles. This seems to be an outstanding idea and I'm surprised it hasn't been more widely adopted - or even that someone hasn't STC'd something.
They were also doing work on better injectors. Another paper has in service photos of injector " spray" patterns of a range of injectors. The CMI injectors really are just a dribble. In the seventies, they had a plan to make it better. But 40 years later nothing has happened.
Really, we run aircraft engines sub optimally because of either cooling limitations or cylinder to cylinder mixture variations. Both of which could be fixed easily if the regulatory environment allowed it.
I'm just reading the proceedings of a symposium on piston aircraft engines from 1976. Both CMI & Lycoming did work with 80% power climbs at best power mixture settings. This regime seemed to work well, but tHeir main concern seems to be that cooling airflow is not reliably good enough. Specifically to the TSIO 360 that I'm interested in Continenta says that the engine needs 5.5 inches of water pressure drop across the engine rather than the common 4 or less.
This work seems to have been in response to a NASA sponsored project to look at emissions. More power to NASA!
The frustrating thing, us that it looks like the engineers at both Continental & Lycoming knew what to do to improve the engines, but it never happened.
I presume the product liability crisis and FAA regulatatory compliance made it too hard / too expensive.
I was also interested in another paper which experimented with what it called a " dog house" or air box which fitted on top of the engine to do away with baffles. This seems to be an outstanding idea and I'm surprised it hasn't been more widely adopted - or even that someone hasn't STC'd something.
They were also doing work on better injectors. Another paper has in service photos of injector " spray" patterns of a range of injectors. The CMI injectors really are just a dribble. In the seventies, they had a plan to make it better. But 40 years later nothing has happened.
Really, we run aircraft engines sub optimally because of either cooling limitations or cylinder to cylinder mixture variations. Both of which could be fixed easily if the regulatory environment allowed it.
Last edited by Old Akro; 20th May 2014 at 02:21. Reason: Spelling
The TIT limit is often misunderstood -- it is not an instantaneous limit. It is a limit for continuous ops at max rotor speed at 1650dF, which would likely only occur at critical altitude. This seldom the case, so there is a buffer built in. You can safely exceed the limit for the time it takes to find peak and reset the mixture either ROP or LOP. Most POHs list this a five-minute period.
All the turbine aircraft I've flown it gets pretty serious if you exceed the maximum TIT limit at any stage of flight for any length of time.
I agree with most of the stuff regarding the LOP stuff but the 1650F in the Chieftain is listed as a red line limitation. The Seneca II also lists 1650F as a red line limitation, havn't got a III manual at hand to check that on the KB. Had to give the engine manual away with the aircraft so don't have access to it any more.
Don't mind the argument for LOP stuff but it will take a lot of convincing to take the needle through a limitation.