LOP again

[Danb]

Thanks I’m aware of that. My Acclaim flys great LOP although I recently flew a couple hour flight ROP  and as mentioned it’s faster than I thought, it took a year to get used to the difference between it and my Bravo. Illl check out the PDF as mentioned 

 

D

[Shadrach]

5 hours ago, Fly Boomer said:

Check out PDF page 84 in this presentation by Mike Busch.  He is not a fan of "lean find".
https://resources.savvyaviation.com/wp-content/uploads/slides_airventure2021/2021-07-27 1000 F7 Leaning the Right Way.pdf

I’m not a fan either. I think it just muddies the water. I’ve also found that if one leans too fast, one can trick the system into identifying the wrong cylinder.

The richest and leanest cylinder of a power plant should be consistent on every flight unless something physically changes. If this weren’t the case, GAMI would not be able to tune a fuel system for consistent air/fuel delivery to each cylinder.

A pilot endeavoring to understand their power plant should know which cylinder is leanest and which is richest. This should only need to be done once. It should be done carefully and methodically. From that point forward the pilot knows which cylinder to reference for leaning, depending on whether or not he wishes to run ROP or LOP. Why would you need to use a lean fine function if you know which cylinder is which?

What I have written below is well understood by most of the pilots on this board, but it bears mentioning for the few that may not yet fully understand engine management using EGT. My intent is to be helpful, not pedantic…

If a pilot wishes to run lean of peak EGT, using the richest cylinder (last to peak) as a reference is the only way to ensure all other cylinders are as lean or leaner than the cylinder being used to set power.

Conversely, if a pilot wishes to run rich of peak EGT, using the leanest cylinder (first to peak) as a reference is the only way to ensure that all other cylinders are richer than the cylinder being used to set power.

If a pilot is operating a turbocharged power plant, knowing how peak EGT on the leanest and richest cylinder correlate to peak TIT is necessary to setting power precisely using TIT. TIT is simply a collective reading of all the heat energy in the exhaust at the turbine inlet. It may be that peak TIT is a reasonable proxy for peak EGT on all cylinders if the fuel/air ratios are well matched. But that is not guaranteed, if it were, there would be no need for tuned injectors.

The goal is to ensure that all cylinders are set within the desired mixture range while also ensuring TIT is significant margin from redline to ensure maximum turbo service life.  Compromises must sometimes be made regarding power, temperature and fuel flow to ensure longevity of the engines components.  A well conforming power plant with minimal FF delta between EGT peaks will require the least amount of compromise.

It’s worth considering that the manufactures are not nearly this detailed when determining POH power recommendations. The factory power settings are guided by performance simplicity and minimizing warranty claims. Anyone who wishes to extract more performance and longer service life from their power plant will likely need to dig a little deeper than the POH.

[exM20K]

Considering the Acclaim has one TIT probe and two turbos, it’s not obvious that the lean find is all that informative.  Knowing the richest, last-to-lean cylinder is more useful to me.  I’m not a fan of the CHT method as it is in no way normalized as is a 50* LOP EGT.  Abnormally cold or hot days don’t mean my engine is making less or more power as measured by CHT.

[Shadrach]

22 minutes ago, exM20K said:

Considering the Acclaim has one TIT probe and two turbos, it’s not obvious that the lean find is all that informative.  Knowing the richest, last-to-lean cylinder is more useful to me.  I’m not a fan of the CHT method as it is in no way normalized as is a 50* LOP EGT.  Abnormally cold or hot days don’t mean my engine is making less or more power as measured by CHT.

I think CHT really is the ultimate measure of of how well a power setting is suited to conditions, but one must do some “normalizing” adjustments in their observations. I’ll take a cruise cht of 365° to be a pretty reasonable in August. 365° on a February day with an OAT 10° not so much. 

[Pinecone]

While APS has not restarted live classes, you can still do the online version.  Same info, but not immediate Q and A with instructors.

I did a lean find early on.   So now I know where I need to be to be sure I am LOP.  I do a big mixture pull to an LOP fuel flow, then fine tune by slowly richening until a cylinder peaks.  Then I lean back from there.

[Shadrach]

On 5/23/2024 at 12:43 PM, Pinecone said:

While APS has not restarted live classes, you can still do the online version.  Same info, but not immediate Q and A with instructors.

I did a lean find early on.   So now I know where I need to be to be sure I am LOP.  I do a big mixture pull to an LOP fuel flow, then fine tune by slowly richening until a cylinder peaks.  Then I lean back from there.

Do you use TIT at all when leaning or simply ensure that whatever EGT setting you’ve chosen gives adequate margin for TIT from redline?

[Pinecone]

I use it to ensure my TIT is within limits.  I try to keep it below 1600.

[keithmiller]

This is what I typically fly on long cross country when I don’t want to stop for fuel . Left KCXO Conroe Texas non stop to KAVL  at 15,000 feet started with 97 gals finished with 28 

[Danb]

Nice low CHTs..

[dkkim73]

On 7/10/2024 at 6:07 AM, Danb said:

Nice low CHTs..

For all the discussion of CHT management in the wider aviation world, I have been amazed how problem-free they seem to be in the Acclaim. I think it was a broker that told me the design naturally took advantage of AOA in different regimes to vary the flow across the cylinders (in lieu of cowl flaps). Granted I don't fly higher settings ROP much (a few times to familiarization) but they just don't go up much. And even the cooling side hasn't been as rapid or as low as I'd feared on descent. Of course, I think it was John Deakin (of APS fame) who said they can't "shock cool" if they're not too hot to begin with. 

[dkkim73]

On 5/23/2024 at 10:43 AM, Pinecone said:

I did a lean find early on.   So now I know where I need to be to be sure I am LOP.  I do a big mixture pull to an LOP fuel flow, then fine tune by slowly richening until a cylinder peaks.  Then I lean back from there.

So you watch the 6 EGTs and go with the one that peaks first from the lean side, leaning back 50F (or whatever) from there? I've read others do that (including taking an iPhone video) I'll have to try it on my next flight. I've been BMP'ing then just getting TIT back up to 1540-1580 depending on how much I'm trying to keep speed up. 

[Danb]

On 5/3/2024 at 8:55 PM, LANCECASPER said:

Long term, for the sake of your Turbos, Turbo transitions - which need to be inspected often, Cylinders, exhaust system, and for that matter even not burning up your tit probe and keeping its accuracy longer, you want your TIT 1600 or under.

For the sake of your wallet also. Depending on your settings, if the reason you are running high TIT is to save fuel, a little extra fuel is almost free compared to most of the above items.

Hey Lancers looks like you have a new neighbor at CLL. Well 100 miles away, it’s the   tweetie bird style White, yellow red left Lancaster after a pre buy a couple days ago, hopefully he/she will be on Mooneyspace. The plane is interesting looking. Good luck to them.

 

D

[LANCECASPER]

1 hour ago, Danb said:

Hey Lancers looks like you have a new neighbor at CLL. Well 100 miles away, it’s the   tweetie bird style White, yellow red left Lancaster after a pre buy a couple days ago, hopefully he/she will be on Mooneyspace. The plane is interesting looking. Good luck to them.

 

D

Ah thanks! I’ll keep an eye out for N67HR.

Looks like they are getting some transition training this weekend at KCLL after the trip home from Pennsylvania.

[Danb]

23 minutes ago, LANCECASPER said:

Ah thanks! I’ll keep an eye out for N67HR.

Looks like they are getting some transition training this weekend at KCLL after the trip home from Pennsylvania.

Yep, they turned the pre buy into an annual 

[dkkim73]

I think I remember that plane from when I was shopping. Super-cool paint job. Looking forward to welcoming the new pilot/owner/family! 

 

[Danb]

Another accolade for the versatile flight profiles of our Acclaims.very similar to Kmillers post above. I left Wilmington De for a trip to Gulfport Ms with an intended stop at Moton Field for fuel. Also LOP. I have no clue how lean I WAS since I always lean towards a fuel flow, so after take off and a slight tailwind and at 12,000 ft for my passenger’s comfort I was flying at 30.5/2450 16.1 gph TIT 1560 CHT 265-300 it appeared I may make my trip without the stop. Went to 28/2450 13.8 GPH TIT 1560 still cool CHTs. Made the 1000 miles in 4.4 hours 20 gallons left in tank. Awesome versatile machine as mentioned no clue how LOP I was. 

When I adjust my mixture I go swiftly to 15 Gph and adjust to attain TIT and never worry about CHTs even wonder if there to cool.

Couldnt make the trip in my Bravo I calculated my fuel savings over the Bravo to approximate $140 and saved about 45 minutes in flight, roughly 18 Gph vs 14.

Gotta love our versatility. 
D 

[exM20K]

8 hours ago, Danb said:

I was flying at 30.5/2450 16.1 gph TIT 1560

what sort of true airspeed were you seeing at 12,000 and that power setting?

-dan

[Danb]

5 hours ago, exM20K said:

what sort of true airspeed were you seeing at 12,000 and that power setting?

-dan

About 188, dropped to 177-179 when I went to 13.8 GPH

 

D

[exM20K]

10 hours ago, Danb said:

About 188, dropped to 177-179 when I went to 13.8 GPH

 

D

That’s about what I see.  You are right about the versatility and capability of these planes.  Big cruise numbers are fun, but quick climbs and fuel efficiency are what cut trip times.  I figure that every fuel stop is minimum 20 minutes added to the trip, and the climb back to altitude costs 10 gallons with only 30 miles covered.  If there is no compelling reason not to, for long trips I’m at 16,000 or 17,000, where the speed, comfort, and efficiency of an unpressurized piston plane are maximized for me.

-dan

[Danb]

14 minutes ago, exM20K said:

That’s about what I see.  You are right about the versatility and capability of these planes.  Big cruise numbers are fun, but quick climbs and fuel efficiency are what cut trip times.  I figure that every fuel stop is minimum 20 minutes added to the trip, and the climb back to altitude costs 10 gallons with only 30 miles covered.  If there is no compelling reason not to, for long trips I’m at 16,000 or 17,000, where the speed, comfort, and efficiency of an unpressurized piston plane are maximized for me.

-dan

For sure Dan the high speeds are nice and there if needed but for life longevity of our engines they appear to like LOP along with cool CHTs, it took a year or so to rid myself of flying my Bravo, which I loved, love Lycomings just the efficiency isn’t there vs acclaim. Also had LR tanks in Bravo which made up for higher fuel use. I’ve been concerned about cool to cold CHTs but now believe that’s the best thing, seems out of sorts seeing 270;CHT vs 370 …

D

 

[Schllc]

5 hours ago, exM20K said:

If there is no compelling reason not to, for long trips I’m at 16,000 or 17,000

I agree with this 1,000%. 
The real sweet spot of the acclaim is 13-18k. I have been higher than that many times, but usually it was an atc directive, or a weather imperative. 
The vast majority of time the best economy and speed to be had is between those altitudes. 
That isn’t to say that more speed couldn’t be had higher, just that the risk vs reward isn’t really there, be it safety or efficiency. 
My opinion is predicated on close to 1,000 hours over five years of flying all over the country at all times of year. 
I would be interested in hearing others opinions on this topic.  

[LANCECASPER]

7 hours ago, Schllc said:

I agree with this 1,000%. 
The real sweet spot of the acclaim is 13-18k. I have been higher than that many times, but usually it was an atc directive, or a weather imperative. 
The vast majority of time the best economy and speed to be had is between those altitudes. 
That isn’t to say that more speed couldn’t be had higher, just that the risk vs reward isn’t really there, be it safety or efficiency. 
My opinion is predicated on close to 1,000 hours over five years of flying all over the country at all times of year. 
I would be interested in hearing others opinions on this topic.  

Agree also. You are above a lot of the weather. You are above most pistons and below most turboprops. The air is generally smooth. In most parts of the country at these altitudes you generally get just about anything you ask for from ATC. 

[Danb]

Another question…. When or if do you enriches the mixture on descent say your completing a long CC at 15,000 ft and you LOP at 15 GPH, all hypothetical, I’ve pushed in the red knob around 18” and 4000 ft or so, or is that not necessary. When I first got the Acclaim I was LOP. going into St Louis and the engine knocked out on the runway quite scary, had enough energy to go off the taxiway and restart.  

[Fly Boomer]

1 hour ago, Danb said:

When I first got the Acclaim I was LOP. going into St Louis and the engine knocked out on the runway quite scary, had enough energy to go off the taxiway and restart.  

I'll be interested in the responses.  I have heard of big-bore Continentals crapping out after landing because they are too rich (mixture all the way in), but never because they are too lean.

[kortopates]

Another question…. When or if do you enriches the mixture on descent say your completing a long CC at 15,000 ft and you LOP at 15 GPH, all hypothetical, I’ve pushed in the red knob around 18” and 4000 ft or so, or is that not necessary. When I first got the Acclaim I was LOP. going into St Louis and the engine knocked out on the runway quite scary, had enough energy to go off the taxiway and restart.  

I never advocate going full rich for landing unless it’s a sea level airport or near that. Even with the turbo it’s easy to be overly rich at idle depending on DA with full rich. But it’s really bad form to land LOP IMO opinion. You want the engine ready to go to high power without any stumbling.
If and when you do go to full power, besides gradually advancing throttle, just be sure to remember mixture and prop are also need to be full.
(One can get away with jamming in the throttle on a 4 cyl engine but it’s very poor form and harmful to a large 6 cyl engine. )


Sent from my iPhone using Tapatalk