The Mysterious Mixture Control

[RoboRay 126]

Maybe to you Ray... maybe that is your definition... not mine. If I cannot conduct a flight "safely" I don't fly (wow what happened to your safety first, second, third?). But that was typically not the case. Nothing out there says I have to have an accident.

 

But then... maybe there is... if I start disregarding the POH... the Eng. Manf. for some webz writer.

 

Actually, no, it's not my definition of safety. It's an aspect of Risk Management, and it's self-evident. If safety is your only consideration, you will not go flying. Period. But you do have other considerations, of course, so you go flying anyway, and it's good for safety to remain your primary consideration. But don't pretend it's the only one, or your simply wouldn't be there to begin with. You assess the risks, put proper controls in place to eliminate or at least minimize them, and you go.

 

Doing something in a certain way because "the book" says to do so is the correct thing to do almost all the time. But every rule does have it's exceptions. And eventually, those exceptions may make their way into the book, because they've been validated as safe. That's what "the book" actually is, a list of things that are confirmed to be safe. That doesn't mean everything outside what's written in the "the book" is inherently unsafe... If something is unsafe, "the book" will explicitly say so. Things not specified as "safe" or "unsafe" in "the book" actually sometimes turn out to be a better or even safer way of doing things. More often, they do not. But it's acceptable to resort to the things in that gray area of neither prescribed nor prohibited when the known-safe method recommended by the "the book" is not an option, or fails, or simply does not apply to the situation in which you find yourself. You may discover a situation where an unconventional method or technique is valid and safe, and you have an opportunity to then contribute a new solution to "the book." I know something about this process, because I help write "the book" for certain naval aircraft. However, I'm not an engine-management specialist, which I believe should have been clear from the start, so I'm not a Subject Matter Expert on this particular topic of discussion.

 

I remind you that my remarks here pertain specifically to using Microsoft Flight. If LoP is heretical and it's adherents should be burned at the stake (even though newer engine and aircraft builders do recommend it), and only RoP is a valid form of leaning, please explain to me precisely how to properly and quantifiably lean MS Flight's RV-6A for RoP operation? Bear in mind all the limitations of Flight in doing so, which I have outlined in the first post. I'm ready and willing to learn.

 

But anyway, I believe I was quite specific in why I suggested running wide open throttle while lean of peak for MS Flight, and you should not be construing that as me advocating that all pilots in the real world should be doing so at all times and in all aircraft. Perhaps you may want to go back and read the whole thing again, because I believe you missed some stuff. At least, I hope you did.

[Great Ozzie 101]

you should not be construing that as me suggesting that all pilots in the real world should be doing so at all times and in all aircraft

 

Good... that is comforting... seriously.

 

With the "tone" of the rest of the post.... it is going downhill in a hurry... so I am punching out at this time. I have no interest in bickering with you. Besides Ray... I have already addressed the (one?) question you asked.

 

-Rob

[RoboRay 126]

I merely respond to "tone" with matching "tone", thanks.

 

Not to my knowledge have you answered the question. Perhaps you could make your answer a bit more clear? And specific for the MS Flight RV-6A, taking into account the issues with the software I mentioned?

 

As to "comforting you", my original post was quite clear, in numerous places, repetitively, that I was discussing MS Flight and its many limitations, and how to work around them. Perhaps you could assess your assumptions a little more thoroughly before jumping up on the soapbox, at length, about them.

 

I take no issue with being corrected. I asked for that very thing, in fact. But correcting me for things I never said or even implied is a little silly.

 

[LAdamson 240]

From what I've been reading, on some newer planes, the builder actually specifies that LoP is not only approved but is recommended, with RoP operations to be avoided in a cruise setting.

 

I've never heard of RoP being avoided in cruise. LoP is always a tradeoff. With LoP, you loose maximum speed & gain endurance.

 

With all the gazillion hours I have in FSX (how I wish were RW hours!) I have always used the automixture checkbox. I have experimented somewhat being an RTWR'er hoping to eek a few extra knots by leaning... seemed to make absolutely ZERO difference in airspeed in what few tests I ran.

 

Above that 6000' mark, FSX always improves in engine performance and airspeed.....with leaning. Since I'm use to the leaning process, as a way of flying at our higher altitude airports, it's something that I always use and notice when simming.

[RoboRay 126]

 

I've never heard of RoP being avoided in cruise.

 

Some Cirrus aircraft specify operating LoP-only for cruise, or so I've read... I certainly don't own one.

[Guest]

The Mysterious Behaviour of people on forums. It's been a very interesting read up to a certain point, but some of the later post could have been PM's as far as I care... Maybe some of you should agree to disagree?

[LHookins 3,105]

Jeroen, you're going to get this behavior any time there is religious fervor about some subject, and some number of people who believe they know more than they actually do. Especially when not everyone is trying to be as tactful as possible.

 

I personally have no opinion on LOP operations, but I do have stong opinions on BS artistry. I know that I don/t have enough information and knowledge about LOP to be entitled to an opinion about it. If in doubt, I'm going to follow the manufacturer's recommendations.

 

One thing that surprises me is that with all the talk about "50 degrees ROP" there's no mention of what the actual temperatures are. The first (and so far the best) article I read on EGT and CHT did talk about "50 degrees ROP" and other things, but also gave advice about specific temperatures.

 

For example, after understanding that article as well as I could, I started flying the FSX Goose at peak EGT,1350 F, which was the recommended max. If I increased the manifold pressure, the EGT would go up and I'd enrich the mixture accordingly to keep the EGT at 1350. If I was flying with less than normal MP, the EGT would be less than 1350. My question is, if max EGT is around 1000, do I still want to enrich to run at 950?

 

Interestingly enough, at the recommended throttle setting, the EGT was maxed at 1350. If you advanced the throttle to the top of the green arc, you'd enrich the mixture and at the end you'd be at max fuel flow and 1350. Unfortunately the only thing that affected the CHT was prop RPM, airspeed and outside temperature. Manifold pressure and EGT had no effect on CHT that I could determine. One good effect was that if you changed prop speed, it would change the manifold pressure, something missing from Flight. With the digital fuel flow and EGT gauges in the FSX Goose, it was a good platform to learn about engine management. While the actual numbers probably weren't close to accurate, at least you could see what happened when you varied settings, and that was probably accurate enough for study, if not for actual flight.

 

Hook

[RoboRay 126]

Well, please do remember that in my post I never said anything about ignoring your POH when flying in the real world. That was a tenuously-connected (at best) tangent brought in to the discussion much later. In fact, if somebody can tell me what I said that gave him that idea (since he said he "left"), I'd love to know so I can make sure a Tutorial-submission doesn't do that. I provided some background material on real-world leaning to help put things in perspective for those new to this topic, but I can remove it if that's distracting people from what I'm actually talking about: leaning in Microsoft Flight.

 

And seriously guys, I'm still waiting for somebody to tell me how to observe that I am properly leaning MS Flight's RV-6A rich of peak, other than just guessing from the Mixture handle percent tool-tip. If there's a quantifiable way to do so, please fill me in. I suggested wide open throttle, lean of peak as an alternative simply because, due to Flight's limitations, I'm unaware of any viable method for finding the peak. This method ensures you stay clear of it but, as I noted right from the start, it's controversial.

 

Or, if somebody more knowledgeable on the subject would prefer to submit a Tutorial on leaning in MS Flight, I'm happy to let them. The question does keep coming up periodically, so it would be nice to have someplace with Flight-specific examples to send them. Either way, I'm good with it. :unknw:

[jcomm 5,969]

Know what guys... I'm jumping in just to tease ya... :-)

 

Ok, here it goes... Should you be uising ELITE, we wouldn't be having this long "discussion" here... You would be able to use all of the methods each of you, RL pilots and non pilots, so well transcribed to the thread, and it would work just like in RL :-)

 

OTOH, I wouldn't have learned so much - a lot more than in all my life as a simmer, thanks to all of your contributions. Actually this MS FLIGHT game has tought me more and gave me more mental activity than any participation in other forums, in the past, I can think of...

 

So, this is great after all... Of course ELITE works even in the Eec I brought to the beach, so, each time I absorb a few more details from your writing, I go ahead and try it in either the C172, the PA24 or any of the CS aircraft that make part of it's fleet... it allways works by the book ;-)

 

... then, I wonder when will I get back home and re-install MS FLIGHT with my new gamertag, and profit from everything that sim/game/whatever can give us, either small pilots in RL like me, non-pilots but real experts in aviation, or professionals like many of you.

 

As I once used to have in my signature...

 

MS FLIGHT... What else?

[LAdamson 240]

And seriously guys, I'm still waiting for somebody to tell me how to observe that I am properly leaning MS Flight's RV-6A rich of peak, other than just guessing from the Mixture handle percent tool-tip.

 

See the following pic, real life RV6A. The EGT is 1325. This is range that I like it. To get there, I'd lean until engine is rough. Then do the Cessna trick of three turns rich. What does this 1325 actually mean? It's only measuring "one cylinder", which is number 3. Number three will usually run the hottest on these 180 HP Lycomings, but you can't always count on that, And where the EGT probe is placed on the exhaust pipe, can also effect the temp readout.

 

It just turns out, that around 1325, my own particular engine would run it's best, not require burning off oil at the mag check, and have good looking spark plugs, when checking them. In flight, if noticed 1150, or 1250...........I'd make it a point to lean some more. I'd often do the lean until rough method, just because it's of interest to me. This is for a 180/constant speed/ carburetor engine.

[RoboRay 126]

Unfortunately, there seems to be no way to display EGT in Flight's aircraft, and they don't run rough as you lean them, until the engine simply stops running from fuel starvation. :mellow2:

[Great Ozzie 101]

I've never heard of RoP being avoided in cruise. LoP is always a tradeoff. With LoP, you loose maximum speed & gain endurance.

 

Me either... the "extra" fuel is used as an aid to engine cooling, etc...

 

My question is, if max EGT is around 1000, do I still want to enrich to run at 950?

 

Yes... if 50° ROP EGT is what is indicated "in the manual". Look at the chart zinfinion posted (also in the last link I will make in my next post). The "setting" remains in a vertical line despite the decrease in power output.

 

there's no mention of what the actual temperatures are

 

The "two" big temps are:

• The relative temp(s) i.e. "Lean to Peak EGT" or "50° Rich of Peak EGT" whatever written in Section 4 of the POH.
  
• The specific temps e.g. "Max TIT not to exceed 1650°F" and/or "Max CHT not to exceed 460°F"
  

Above that 6000' mark, FSX always improves in engine performance and airspeed.....with leaning.

 

IIRC I was testing with the A2A P-51H (actually an FS9 Model). Given your observation, I need to go back and test each Make / Model with AFSD.

 

Here's a line I found about LOP that gave me a chuckle:

 

"Regarding lean of peak vs rich of peak - my mechanic says that lean of peak operations improves his business sufficiently that he too can afford to fly!"

 

Ok enough horsing. :Big Grin:

[Great Ozzie 101]

Actually, no, it's not my definition of safety.

I am going to keep this on topic... as I said... no interest in bickering with you.

 

if somebody more knowledgeable on the subject would prefer to submit a Tutorial on leaning in MS Flight

 

More knowedgeable... hmmm... for a game? I mean leaning in the sim, unless one is referring to RW ops (and many do ask about this) is as about as difficult of leaning your mower... you adjust the "little screw" till it roughens and then back the other way a bit... not rocket science.

 

If on the other hand, one is speaking how it relates to RW Leaning... and this is what I find facinating... as there really is some science there and a host of factors to be considered.

 

Which leads me to my next point about the "tenuous connection"...

 

That was a tenuously-connected (at best) tangent

 

Tenuously connected... ok...

 

Let's take an example from this paragraph:

 

I remind you that my remarks here pertain specifically to using Microsoft Flight.

 

Ok fine and good. We're talking sim...

 

But the very next sentence you vault into this melodramatic statement about Real World Lean of Peak (what builders btw?). Then you want a proper leaning (who knows what "proper" means if not RW) for the FLIGHT RV-6... and we jump back into the Sim World... since I am to bear in mind the all the limitations of FLIGHT.

 

So which is it? We talking sim? Real World?... this stuff is so convoluted how could one not possibly see how intertwined it is... and you call the connection tenuous. Proper in the sim? C'mon Ray... it's a game... you play how you want to play or whatever works best for you.

 

Then there's the folks... so many here who want to simulate RW ops (bravo! btw) and... "it's tenuous..."?

 

Plus the very act of leaning is something done with real engines (not game specific)... again, tenuous?

 

But anyway, I believe I was quite specific in why I suggested running wide open throttle while lean of peak for MS Flight

 

All the "power" to you if you can find "an easy way" to lean. Sorry I did not take it that way... as was the second time you brought it up (coming from RW ops). As I said, I have brought up the Lycoming SI on Leaning... but here it is again...

 

(Here's what you brought up a few days ago and my response that I never posted)

 

==================

But in the absence of any way to actually find the Peak

 

There is a way to lean properly... and it is found in Lycoming Service Instruction No. 1094D

 

"3. For cruise powers where best power mixture operation is allowed, slowly lean the mixture from full rich to maximum power. Best power mixture operation provides the most miles per hour for a given power setting. For engines equipped with fixed pitch propellers, gradually lean the mixture until either the tachometer or the airspeed indicator reading peaks. For engines equipped with controllable pitch propellers, lean until a slight increase of airspeed is noted."

 

It's not going to be much... like RPM rise in a Warrior is 30 to maybe 40? rpm.

 

LOP/WOT may be the way to go.

 

You realize he is referring to aircraft with a fixed pitch prop (he's using his Warrior experience as an example).

 

I would by far trust the Engine Manufacturer over someone with a smidge of emirical evidence. But for a sim/game sure why not? Just don't expect to use this technique with any CFI with a lick of sense about proper engine management techniques.

 

Here's a good article from AVWEB about leaning (along with some links for other articles): "Are You Wasting Avgas?" http://www.avweb.com...s_196816-1.html

 

====================

 

To me, unless I can gain extra speed from leaning (some sort of an advantage) I see it as pointless. Reasons:

 

Based on using proper leaning technique for the Engine in use... That is... I need to know how to lean that engine (what does the manual say? do I even have a manual???)

• Is leaning going to duplicate RW performance. (Airspeed, Fuel Flow)
  
• Is leaning going to duplicate RW indicators (Airspeed, CHTs, EGTs TIT(s) engine response)
  
• Is improper leaning going to "cost" me something (e.g. engine failure)
  

Bottom line... if I can gain an operational advantage from leaning... sure I will use it. Other than that... what's the point? I do not want to spend the time messing around trying to answer those (3) questions, as "I'd rather be flying". That's just my opinion, of course... and to each his own. And I am "prejudiced" as I've messed with it for many hours anyway.

 

 

Some Cirrus aircraft specify operating LoP-only for cruise, or so I've read...

 

It would be very interesting to see an example (please).

 

The closest I have come to seeing this is in the SR22T:

 

Cirrus Design - POH Section 4

SR22T - Teledyne Continental TSIO-550-K

 

"Recommended cruise is at a Lean of Peak / “Best Economy” mixture setting. Cruise leaning, i.e. leaning below full rich fuel flow, is only approved with manifold pressure settings of 30.5 in.Hg or less."

 

This turbocharged plane has no prop control... It does have nice (big) "gauges" on the MFD for all 6 CHTs and EGTs, 2 TITs... even a % Power gauge (sweet).

 

----------------------------------

Here is what I found for the SR22

 

Cirrus Design - POH Section 4

SR22 - Teledyne Continental IO-550-N

 

Cruise

Normal cruising is performed between 55% and 85% power.

 

Cruise Leaning

Exhaust gas temperature (EGT) may be used as an aid for mixture leaning in cruise flight. For “Best Power” use 75% power or less. For “Best Economy” use 65% power or less. To adjust the mixture, lean to establish the peak EGT as a reference point and then adjust the mixture by the desired increment based on the following table:

 

Mixture Description Exhaust Gas Temperature

Best Power 75° F Rich Of Peak EGT

Best Economy 50° F Lean Of Peak EGT

--------------------------------------

 

Maybe it's as you said Ray, simply a matter of "speaking past one another"... in your case solely about simming... in my case... RW ops and applying it to simming.

 

A choice quote from the artice I linked above:

 

As far as operating Lean of Peak (EGT or TIT) I leave you with Lycoming's response on the matter: "The 'New' Old Leaning Technique" http://www.lycoming....ces/SSP700A.pdf

 

And zinfinion... pay particular attention to page 3 "This is where the plot thickens"... about power settings and detonation, fuel metering units and fuel schedules and turbocharging & fuel metering.

[RoboRay 126]

I am going to keep this on topic... as I said...

 

Then perhaps it would have been better to not go off-topic to begin with.

 

leaning in the sim is as about as difficult of leaning your mower... you adjust the "little screw" till it roughens and then back the other way a bit... not rocket science.

 

So, proper leaning in MS Flight is to lean the mixture until the engine actually shuts off from fuel starvation (because it never does roughen in any other way), then go back a little richer until it restarts. Got it. Thanks for your input.

 

I'm pretty sure that's going to be just a little bit lean of peak, though.

[Great Ozzie 101]

Then perhaps it would have been better to not go off-topic to begin with.

 

"Physician... heal thyself."

 

Thanks for your input.

 

Yeah whatever works... welcome btw.