Emphasis on LOW power settings!!!
Emphasis on LOW power settings!!!
Chip Allen
SWT Aviation, Inc.
Cubcrafters Southeast Sales Center
Marietta, GA
This whole thread falls into the same category as "wheel landing or "3-point"; everyone has an opinion. I'm a huge proponent of LOP operation in the Baron and in the Carbon Cub. Several years ago, I attended the Advanced Pilot Seminar in Ada, OK, put on by some real experts in the area of engine operation. One of the instructors, John Deakin published an article last month as a "rebuttal" to the Lycoming publication listed in a previous post. For those interested in really getting into the "nuts & bolts" of LOP Operation, you can read the entire article in the following link, or to make it easier, I've attached as a PDF. I'm certainly not an expert in this field, but my personal experience has been outstanding with both large and small block, fuel injected and carbureted engines; operated LOP they run cool, they save a LOT of fuel, minimal sacrifice in airspeed, and easily reach TBO with no cylinder problems.
http://www.advancedpilot.com/article...articleid=1838
Chip Allen
SWT Aviation, Inc.
Cubcrafters Southeast Sales Center
Marietta, GA
What is your thinking of LOP operation of the CC in reference to the statement: "Bottom line is that because of limitations of the carburetor and induction system, in my airplane you can only run half the engine LOP without it getting pretty rough." ? Not being knowledgable about this engine and soon to own one, I am interested in what these "limitations" in this engine are?
I would tend to be swayed to LOP operation for the CC if it indeed was feasible ?
Thanks-Steve
Last edited by Steve Y; 07-25-2013 at 09:07 AM.
I will step in with my experience on LOP.I have had very good luck on Continental fuel injected engines with GAMI balanced injectors. I have managed to successfully run LOP in a Turbo carbureted 182 with an O-540. The problem with other carbureted engines (like my 0-200) is the induction system does not supply fuel in a critically balanced amount to each cylinder. That cause some cylinders to lean at too extreme a range for successful LOP operations. Fuel injected with balance injectors is easy, most carb engines (Continental especially) will not run smoothly LOP. You really should have full engine monitoring (EGT all cylinders) to attempt this.
Last edited by cityrancher; 07-25-2013 at 10:21 AM.
Okay, here's my very scientific leaning method (my CC doesn't have any of the more sophisticated instrumentation):
I get to cruise altitude, power back to the proper rpm for the altitude (That means its making 80 hp, right?) and then pull out on the mixture knob till the engine just about quits; Maybe my hearing is bad anymore, but I can't hear any change in the sound of the engine until it almost dies. Once that happens I push the control back in until it starts running again. and that's where I run until I get where I'm going.
Am I doing it right or should I be leaning some other way?
Rick,
as Ive been reading thru all these posts, Im also thinking they must have some CGT or CHT temp gauges on their glass panels. I too have the basic set up with no temp gauges other than engine oil, so I follow the same procedure you do. I pull the mixture back a click at a time, as it does start to cut out quickly when it hits that point. I then push it back in a couple clicks until its running smoothly.
I am having a Fuel Totalizer and flow meter installed; with that Ill be able to see my fuel flow and compare it to what the guys are getting using LOP.....
Rick
This is just my opinion based on 20 hours of experimentation. I have been learning LOP on my new CC11 with Dynon and seeing how the results compare to my old Super Cub procedure (where I did not monitor temps other than oil) of "lean until rough and then richen a little". There is more to this than I will try to detail here. But the bottom line is when I see what is happening to EGT and CHT I feel bad about what I must have done to my O-320. Without the EGT and CHT detail and the warning indications to keep ahead of the trends I could not properly manage LOP on a hot day based on what I can see happening now. This is probably true for ROP, too. With the detail info I can do it. Fuel flow varies so much with changes in density altitude and MP that a standard would be difficult to maintain. Not to mention the need to manage air speed when temps become critical.
I think the CC340 is probably more sensitive than the O-320 so maybe I wasn't as cruel as it appears. I am really glad I have the Dynon for this reason among many others.
Just wondering if anyone has furthered the art of how to lean the CC340? I do have full instrumentation of EGT's and CHT's but no program for setting LOP or ROP, so I just do the lean till rough then back to smooth and a couple more clicks rich to be sure. This gives a fuel flow of about 6.3 gph at 2150 RPM at 1000 ft PA, which is higher than other postings I see here. Highest EGT is about 1250, CHT about 380. Should I be doing something more scientific? I'm about to embark on a remote area (of Australia) trip with very little fuel availability so need to extend the range. I will run at lower RPM but wondering how aggressive I should get with leaning.
Paul.
Paul,
I assume from your post that you have a D180 or similar. What I do is when settled into cruise attitude pull the rpm to whatever you want and assuming you are less than 70% power (2150 rpm is about45%) lean till you have peak egt on the Dynon, note the highest egt, then keep leaning one notch at a time until the egt is about 50 degrees lower that the noted temp eg 1350 down to 1300 You are now at the best setting for best economy and slightly below peak power at that rpm,
you cannot hurt your engine at this setting and you should see at 2150 rpm a fuel flow of about 22.5 litres/hou(5.9g/h).
and 95 mph. I find my fuel flow( in litres / hour) roughly matches the rpm. So at 2300 I get LOP about 24 l/h(6.3g/h) and 2400 about 25 l/h( 6.6 g/h) and 115mph .
Hope this helps and have a great trip. some time in the future I would like to arrange a fly in of CC's somewhere in the middle of Oz. let me know your contact details
Bruce EX 041
Melbourne
Thank you, Bruce. That is very helpful, I will try that, it sounds like a good method. When I can get to it I will install the carby mods as that should also help with getting most cylinders on the same page.
I'm in Far North Qld. I will be 'on' for a trip around the Top End any time you can rustle up some CC's to join in. I've emailed you my contacts.
Paul.