A tale of 2 Rockets, can you figure it out?

[A64Pilot]

33 minutes ago, Fly Boomer said:

Oxygen?  Long glide not helpful.

Sure you have to wear a mask, but if needed you can get down fast, bedsides carry two sources. I didn’t but maybe guess I should have. I know in the crop duster I could have probably come down at 5,000 FPM, never tried in a Mooney but 3,000 ought to be easy?

I just don’t think it’s a risky maneuver is all and I’m an old helicopter guy and we thought any higher than you could get on the ground in one minute was risky. Many wouldn’t fly with me on engine performance runs as I’d have to go as high as 12,000 sometimes and helicopter guys really, really don’t like that. 12,000 was the max for the charts so usually an engine would top by 10,000 or so

[Fly Boomer]

21 minutes ago, A64Pilot said:

I just don’t think it’s a risky maneuver

Get a stopwatch and see how long you can hold your breath.

[carusoam]

Sooooo…….  
 

Flying above 20k’….

• TUC charts indicate you don’t have a lot of time to recognize you are having an O2 problem…
• At 28k’ you can hold your breath longer than you can stay conscious according to the charts…
• Simple challenges and you can be asleep before you can find an answer….
• Get AP to descend and stop at 10k’… altitude select would be your friend.

E-descents…

• E-descents in a Mooney with speed brakes can exceed 5kfpm…
• From 20k’ the ground is still four minutes away…
• And you will still be screaming through the traffic pattern at speed…. 160kias
• So add another minute…. To get slowed and land…

Modern technology…

• Even my Fitbit shows my dissolved O2 percentage… continuously…

 

PP thoughts only, not a test pilot…

 

Best regard,

-a-

[A64Pilot]

On 8/31/2022 at 9:02 PM, Fly Boomer said:

Get a stopwatch and see how long you can hold your breath.

Long enough to put another mask on. It was a test flight, I’ve flown many of those with seat cushions removed so that I could wear a parachute, you do things to mitigate danger. I guess when I was in a crop duster at FL250 I should have had a back up O2 supply but didn’t think about it, but I should have because as a cave diver I’d never enter a cave without multiple independent gas supplies.

 

[Fly Boomer]

25 minutes ago, A64Pilot said:

Long enough to put another mask on. It was a test flight, I’ve flown many of those with seat cushions removed so that I could wear a parachute, you do things to mitigate danger. I guess when I was in a crop duster at FL250 I should have had a back up O2 supply but didn’t think about it, but I should have because as a cave diver I’d never enter a cave without multiple independent gas supplies.

I guess maybe Bob Kromer was a chicken, but he said "never again".

[A64Pilot]

2 hours ago, Fly Boomer said:

I guess maybe Bob Kromer was a chicken, but he said "never again".

Never said he was a Chicken, just wondering why he didn’t want to do it again, perhaps the Turbo was working harder than it should, in turbines we monitor and have RPM limits for the gas producer, on Turbo’s we don’t monitor RPM.

Or maybe some other mechanical limit, vapor lock maybe, the thinner the air gets, the lower the boiling point of the fuel, or other unknown reasons, wondered if there was some kind of mechanical limit. Airplanes I usually fly the engine power just goes away until the thing just can’t climb any higher.

I didn’t like being that high in a Crop Duster but did it a dozen or more times, but it wasn’t unsafe, but it was a little like standing on the edge of a tall building, felt uncomfortable.

[Shadrach]

On 8/31/2022 at 8:09 AM, Austintatious said:

Neither engine runs rough when we go LOP... Until we go TOO LOP.  The issue is that we get to the temp limit of the TIT if we are at any power setting over 55%.  It would be nice to run 70% power and LOP.... but we simply cannot as the TIT will be too high.  When we have tried, we keep leaning until the TIT starts to dropto safe levels, but by the time it does, we get an onset of rough running.

 

It’s hard to have a meaningful discussion about two different engines of the same make and model performing differently within the scope of an Internet forum.
I can’t say why the two are limited by different parameters when they should be acting the same. If I were in your shoes, I would The one with the widest available operating range and said about tweaking it to expand that range. That would mean verifying timing, pro position, baffle seal condition and position.  Don’t focus on the differences, focus on making one engine operate to your ideal and then try to duplicate it with the other.

[A64Pilot]

9 hours ago, Shadrach said:

 

It’s hard to have a meaningful discussion about two different engines of the same make and model performing differently within the scope of an Internet forum.
I can’t say why the two are limited by different parameters when they should be acting the same. If I were in your shoes, I would The one with the widest available operating range and said about tweaking it to expand that range. That would mean verifying timing, pro position, baffle seal condition and position.  Don’t focus on the differences, focus on making one engine operate to your ideal and then try to duplicate it with the other.

It’s the myth of LOP, that is to say I can go just as fast but burn less fuel. Well it’s true sometimes if we define fast, if we are willing to accept fast as a number well less than maximum it’s true, but if you want to fly at the fastest maximum speed attainable, it’s just not true, to go fangs out, hair on fire, that’s ROP.

Which is not to say LOP doesn’t have its place, it certainly does, when seeking max efficiency LOP will get you there. I fly LOP almost always, but I accept the airspeed loss. TANSTASFL

[T. Peterson]

On 8/31/2022 at 7:39 PM, A64Pilot said:

Sure you have to wear a mask, but if needed you can get down fast, bedsides carry two sources. I didn’t but maybe guess I should have. I know in the crop duster I could have probably come down at 5,000 FPM, never tried in a Mooney but 3,000 ought to be easy?

I just don’t think it’s a risky maneuver is all and I’m an old helicopter guy and we thought any higher than you could get on the ground in one minute was risky. Many wouldn’t fly with me on engine performance runs as I’d have to go as high as 12,000 sometimes and helicopter guys really, really don’t like that. 12,000 was the max for the charts so usually an engine would top by 10,000 or so

Years ago in the Marine Corps I had a training mission to take jumpers to 10,000 feet in a CH-46. ( Tandem rotor Boeing Vertol BV -107) I didn’t like that one bit. Not only were the controls mush, but I was thinking please don’t let me get a transmission chip light!

[Shadrach]

12 hours ago, A64Pilot said:

It’s the myth of LOP, that is to say I can go just as fast but burn less fuel. Well it’s true sometimes if we define fast, if we are willing to accept fast as a number well less than maximum it’s true, but if you want to fly at the fastest maximum speed attainable, it’s just not true, to go fangs out, hair on fire, that’s ROP.

Which is not to say LOP doesn’t have its place, it certainly does, when seeking max efficiency LOP will get you there. I fly LOP almost always, but I accept the airspeed loss. TANSTASFL

What would you say to the TAT, TN’d A36 Bonanza guys who can run 80% power LOP all day long… cooler, faster and on less gas than running 75% ROP? 
 

This has nothing to do with mixture myths and everything to do with the components of these particular aircraft. Throwing gas at an engine makes a lot of warts go away. Mixtures on the lean side require an engine that is conforming in all parameters. Fuel delivery, air delivery, spark and cooling air flow. The reality is that it is challenging to attain the precision required in all of those parameters with an off the shelf Aeroengine. Some designs are less challenged than others.  Many folks with turbos can actually run faster, on less gas and lower CHTs on the lean side. I don’t blame the OP for trying to get there.

[A64Pilot]

2 hours ago, Shadrach said:

What would you say to the TAT, TN’d A36 Bonanza guys who can run 80% power LOP all day long… cooler, faster and on less gas than running 75% ROP? 
 

That they can’t run greater than 80% LOP. If you could run just as hard LOP than you can ROP, then there would be no reason to ever run ROP. The LOP limit is less than 100% power, and this is where you and I disagree, I say running high power LOP can be dangerous as in its not hard to inadvertently get into a position to do engine damage. Your close to peak at the efficient LOP temp and if at high power letting the temp creep just a little towards peak can cause engine damage

He’s hitting temp limits at high power LOP, limits that would resolve if he could run deeper LOP but can’t because there is a limit as to how lean you can run, but you don’t want to be that lean even if you could, because it’s inefficient, you want to run at BSFC peak, and that’s one EGT, unfortunately it seems that EGT seems to be higher than the turbos limit at high power

But we have to ask why those limits would be resolved by running leaner, well as HP when LOP is determined by fuel flow reducing fuel flow reduces power, lower power, less heat. Rather than trying deeper LOP and operating less efficient, I’d say stay at the efficiency peak and pull the throttle back, either one reduces power. But if your at the most efficient EGT, your making the most HP possible with the least fuel.

Turbos and engines are not identical, I used to “blueprint” Turbos on drag bikes years ago, the clearance between the cold side pin wheel and its housing is set by shims under the pinwheel, little thin washers, so I would put  Prussian blue on the housing and turn the pinwheel and where it touched the housing polish out the part that touched and keep doing this until you closed up the gap as much as possible. Both the speed it built boost and the total boost was significantly higher, only point I’m making is that some turbos are better than others, just as some engine are better than others, there will be variations. Just like different cylinders peak EGT temp will be different

However if it were me I’d take a good look at baffling, can’t hurt, need to always do that anyway.

Even temp sensors have variances, some greater than others, best I’ve ever seen are the ones EI uses. Turbines will have a bunch of temp sensors and the temp you see shows you the average, maybe six or more to try to get accuracy, turbo’s have one.

Military engines we would Jet cal every phase (annual) where accuracy was checked and adjusted if necessary, so far as I know we never do in GA.

[Will.iam]

9 minutes ago, A64Pilot said:

That they can’t run greater than 80% LOP. If you could run just as hard LOP than you can ROP, then there would be no reason to ever run ROP. The LOP limit is less than 100% power, and this is where you and I disagree, I say running high power LOP can be dangerous as in its not hard to inadvertently get into a position to do engine damage. Your close to peak at the efficient LOP temp and if at high power letting the temp creeps just a little towards peak can cause engine damage

He’s hitting temp limits at high power LOP, limits that would resolve if he could run deeper LOP but can’t because there is a limit as to how lean you can run, but you don’t want to be that lean even if you could, because it’s inefficient, you want to run at BSFC peak, and that’s one EGT, unfortunately it seems that EGT seems to be higher than the turbos limit at high power

But we have to ask why those limits would be resolved by running leaner, well as HP when LOP is determined by fuel flow reducing fuel flow reduces power, lower power, less heat. Rather than trying deeper LOP and operating less efficient, I’d say stay at the efficiency peak and pull the throttle back, either one reduces power. But if your at the most efficient EGT, your making the most HP possible with the least fuel.

I thought diesel engines do LOP only now. They only squirt in the amount of fuel they need idle cruise and acceleration. Basically limiting HP by fuel rather than conventional gas engines do by throttle. 

[carusoam]

If we only had an airflow sensor….

the ROP vs. LOP discussion would get much easier…. 

ROP is airflow limited…

LOP is fuel flow limited…

%HP is a function of the limited resource…

 

cruising with finely tuned cylinders and turbos would be fun… just not the best for the CB club…

-a-

[A64Pilot]

50 minutes ago, Will.iam said:

I thought diesel engines do LOP only now. They only squirt in the amount of fuel they need idle cruise and acceleration. Basically limiting HP by fuel rather than conventional gas engines do by throttle. 

They do, and always have normally back since day one, but pump enough fuel into a Diesel and it goes ROP, keep pumping fuel in and it blows black smoke. You can clean up a lot of the smoke with Nitrous oxide or Propane

On edit, Not to confuse I believe a normal stock Diesel is always LOP

A Diesel and a turbine are both ultimate LOP engines

A Diesel has no throttle valve, so even at idle it draws in a full charge of air, and squirts in a tiny bit of fuel, for that reason a Diesel has no vacuum, theoretically if you measured MP in a Diesel it would be atmospheric always regardless of power output (NA motor)

Thats one reason why a Diesel is more efficient, but another important difference is that a Diesel has no fuel in the cylinder, it’s injected right at the point it needs to begin the burn, where a spark ignition motor draws in air and fuel together, a Diesel can’t be made to pre-ignite because there is no fuel present until the right moment.

Mazda I believe is or soon will build essentially a gasoline Diesel engine.

https://insidemazda.mazdausa.com/the-mazda-way/technology/five-things-need-know-worlds-first-compression-ignition-engine/

Mazda is determined not to drop ICE and jump on the electric bandwagon but to continue to develop and evolve ICE

Gas ir rated in Octane, essentially how hard it is to ignite, higher Octane = harder to self ignite.

Doesel is rated in Cetane, essentially a measurement of how easy it is to ignite. High Cetane = easier to ignite.

Thats dumbed down but essentially pretty much it.

[A64Pilot]

Another reason Diesels are more efficient is that they can take a little bit of fuel and because it’s not in a homogenous  mix with the air it can be burned and this little bit of fuel can heat a full charge of air. Normal spark motors as they can’t have fuel in just a small area of the cylinder have to restrict the air with the fuel so at part throttle there is less air to heat and expand.

Enter the Stratified charge engine, which can run smoothly very deep LOP like a Diesel, I think Honda built one in the 80’s? but pollution control I think was difficult.

https://en.wikipedia.org/wiki/Stratified_charge_engine

I read the Wiki article and it seems Stratified charge isn’t dead, I thought it died with Honda

[aviatoreb]

My rocket is like yours.  It’s nicely balanced through careful tuning of injectors, baffling etc and runs smoothly lop.  But running lop more than 55% power or so results in higher tit than I like. So 55% is my personal lop limit.  I run that setting maybe 25% of the time. And higher power settings rop the rest of the time.

[Will.iam]

4 hours ago, aviatoreb said:

My rocket is like yours.  It’s nicely balanced through careful tuning of injectors, baffling etc and runs smoothly lop.  But running lop more than 55% power or so results in higher tit than I like. So 55% is my personal lop limit.  I run that setting maybe 25% of the time. And higher power settings rop the rest of the time.

Do you have electronic ignition or straight mags? What rpm are you running lop?

i find that the further lop the harder the fuel mixture is to light and the slower the burn rate to the point the flame is still burning when the exhaust valve opens. Electric mag will help more gas to be lit increaseing the flame front speed, Lowering the RPM’s gives the flame front more time in the cylinder to burn before the exhaust opens or less lop speeds up the flame front finishing the burn sooner. I’m just saying 55% seems low to keep tit below 1550. I run 65% with 2500 RPM at 1550 tit. If i want to go higher power i have to slow the rpm’s which counters increase power somewhat. 

[aviatoreb]

4 hours ago, Will.iam said:

Do you have electronic ignition or straight mags? What rpm are you running lop?

i find that the further lop the harder the fuel mixture is to light and the slower the burn rate to the point the flame is still burning when the exhaust valve opens. Electric mag will help more gas to be lit increaseing the flame front speed, Lowering the RPM’s gives the flame front more time in the cylinder to burn before the exhaust opens or less lop speeds up the flame front finishing the burn sooner. I’m just saying 55% seems low to keep tit below 1550. I run 65% with 2500 RPM at 1550 tit. If i want to go higher power i have to slow the rpm’s which counters increase power somewhat. 

Yes I have surefly.  But yes I have habit of 2300.  Maybe I’ll try 2200.  But as an arbitrary line in the sand I’m shootings for below 1600.  1550 is not attainable.

[carusoam]

With TIT…

We are looking for a temp that doesn’t allow the turbo vanes to deform….

Too hot… vanes elongate / stretch and hit the case….

Hitting the case… causes them to shorten and turn into nubs…

Nubs have large gaps between their tips and the case… leaking pressure…. Keeping the turbo from behaving like a turbo…

 

Some redlines are something like 1700 or 1750°F…

Some people use 1650°F as their operational target… allowing some flexibility to not generate turbo vane nubs…

 

Not sure if there is any value in operating TIT below 1650….

These temps are soooo high above the oil’s ability to exist…. For extended periods of time…. It is important for the oil’s health to keep moving… and not hang out…

 

Kind of like CHT limits people use… 380 is a good operational target… when redline is up around 500°F or so…

Running CHTs at 360°F wouldn’t make things any better….

 

Of course… if unsure what your actual TIT or CHTs are because of wacky instruments…. Focus on instrument and sensor improvements to get them in line with where they are supposed to be…. 

 

There must be a good TIT thread around here…

If not… let’s start one…

Best regards,

-a-

[Shadrach]

On 9/4/2022 at 12:04 PM, A64Pilot said:

That they can’t run greater than 80% LOP. If you could run just as hard LOP than you can ROP, then there would be no reason to ever run ROP. The LOP limit is less than 100% power, and this is where you and I disagree, I say running high power LOP can be dangerous as in its not hard to inadvertently get into a position to do engine damage. Your close to peak at the efficient LOP temp and if at high power letting the temp creep just a little towards peak can cause engine damage

He’s hitting temp limits at high power LOP, limits that would resolve if he could run deeper LOP but can’t because there is a limit as to how lean you can run, but you don’t want to be that lean even if you could, because it’s inefficient, you want to run at BSFC peak, and that’s one EGT, unfortunately it seems that EGT seems to be higher than the turbos limit at high power

But we have to ask why those limits would be resolved by running leaner, well as HP when LOP is determined by fuel flow reducing fuel flow reduces power, lower power, less heat. Rather than trying deeper LOP and operating less efficient, I’d say stay at the efficiency peak and pull the throttle back, either one reduces power. But if your at the most efficient EGT, your making the most HP possible with the least fuel.

Turbos and engines are not identical, I used to “blueprint” Turbos on drag bikes years ago, the clearance between the cold side pin wheel and its housing is set by shims under the pinwheel, little thin washers, so I would put  Prussian blue on the housing and turn the pinwheel and where it touched the housing polish out the part that touched and keep doing this until you closed up the gap as much as possible. Both the speed it built boost and the total boost was significantly higher, only point I’m making is that some turbos are better than others, just as some engine are better than others, there will be variations. Just like different cylinders peak EGT temp will be different

However if it were me I’d take a good look at baffling, can’t hurt, need to always do that anyway.

Even temp sensors have variances, some greater than others, best I’ve ever seen are the ones EI uses. Turbines will have a bunch of temp sensors and the temp you see shows you the average, maybe six or more to try to get accuracy, turbo’s have one.

Military engines we would Jet cal every phase (annual) where accuracy was checked and adjusted if necessary, so far as I know we never do in GA.

LOP power table from the FAA approved AFM for Cirrus SR22T (which is a torbo normalized system from TAT like the A36). 

When one makes a statement like “That they can’t run greater than 80% LOP”. One should do the research to ensure that they know what they’re taking about. If you speak with authority without actually doing the work you risk looking foolish. TANSTAAFL…

I have been running high power LOP for over a decade and monitoring the effects. I know several turbo operators that do the same. That is what my opinions are based on. On what are you basing yours? 

[Will.iam]

16 hours ago, aviatoreb said:

Yes I have surefly.  But yes I have habit of 2300.  Maybe I’ll try 2200.  But as an arbitrary line in the sand I’m shootings for below 1600.  1550 is not attainable.

Carusoam had a good point to search about high tit. I did and mooneyspace had a great thread about a pilot that had a 231 that was getting 1630 tit going lop had gami injectors so was confused why he had higher than normal tit compared to others on the forum. Long story short his gami spread was 1 gph between the richest and leanest. Once they swapped injectors and got the gami spread down to .2 he was able to get same performance but his tit was 1580 instead of 1630. 

 

 

Edited September 5, 2022 by Will.iam
Found the thread and added the link.

[Shadrach]

3 hours ago, Will.iam said:

Carusoam had a good point to search about high tit. I did and mooneyspace had a great thread about a pilot that had a 231 that was getting 1630 tit going lop had gami injectors so was confused why he had higher than normal tit compared to others on the forum. Long story short his gami spread was 1 gph between the richest and leanest. Once they swapped injectors and got the gami spread down to .2 he was able to get same performance but his tit was 1580 instead of 1630. 

One of the advantages of Turbo Normalized engines over TSIO engines is lower EGTs and therefor lower TITs. The TAT set up for the Bonanza is dirt simple to operate. No ROP leaning above 25”; you must be full rich or LOP. LOP settings are permissible up to max MP of 31”.
 

With 8.5:1 pistons, TITs typically remain in the 1500s. Exceeding TIT redline is not as much of a  concern in these engines.

[Will.iam]

Yes tit in my TC engine is my limiting factor. At 62% power 9.5 FF and lop i get 1550

at 65%  power 10 ff land lop i get 1580 and that is about as high a tit as i like to go on a cruise power setting. Sometimes I'll dial the rpm’s back from 2500 until i get the tit back under 1550 but my speed drops off as well. It’s analogy like driving a car down the highway in a lower gear than in overdrive. I’ll take the reduced wear and maintenance at the sacrificed speed.