Today's Message Index:
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1. 08:17 PM - Re: ROP versus LOP...might be off-topic for some (Noel Loveys)
2. 08:38 PM - Re: ROP versus LOP...might be off-topic for some (BobsV35B@aol.com)
Message 1
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| Subject: | ROP versus LOP...might be off-topic for some |
Lynn:
For what it's worth my training told me that LOP is ok as long as you are
not drawing any power. If you are in a situation where power has to be
pulled you are better off at ROP. If you are constantly running LOP keep a
close eye on the top of your pistons.
Noel
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: Saturday, August 15, 2009 3:45 PM
jabiruengine-list@matronics.com
Subject: JabiruEngine-List: ROP versus LOP...might be off-topic for some
Over the last week, I've had some fun making some tests with my newly-
installed Rotec TBI-40 mixture-adjustable, carburetor-replacement
device on my Jabiru engine. I don't know whether two of these units
will work on a Rotax, so many of you might want to hit the delete key
right now.
For the most part, I was flying it LOP (lean-of-peak), but yesterday
I made a flight and decided that I would try ROP (rich-of-peak). In
flying LOP, the articles I've read say to keep the power requirements
low, and LOP will work and you won't burn the engine down. I was
amazed that this LOP thing even works at all, let alone work as well
as I've found that it seems too....I guess I'm still a bit of a
skeptic. After all, if going lean is a bad thing, how can going even
leaner be a good thing? I won't argue whether or not it's a good or
bad thing, and there are those of you that may not be able to do any
leaning at all, as I was until I got this unit.
Three days ago, I made two trips totaling 475 miles, using LOP
settings, and yesterday I made a 310-mile trip, using ROP settings. I
had flown the 475 miles leaning out the engine until peak EGT, then
leaning more until the engine was obviously low on power, and I
contentedly flew at this setting, watching the scenery crawl by.
Yesterday I decided to actually GO somewhere, and never mind the fuel
saving, I just wanted to get there, so I decided to try ROP.
Here are the average numbers from those trips:
LOP: 27.77 miles per gallon; 3.3 gallons per hour; 93.14
miles per hour
ROP: 23.66 miles per gallon; 4.37 gallons per hour; 103.3 miles per
hour
Altitudes on all of these flight were anywhere from 3000' MSL (with a
base of 1000') to 10,000 MSL, with throttle settings from 2600 rpm to
3050. Fuel flow as seen on the gauge, ranged from 2.5 gallons per
hour to 5.0 not including takeoffs, but including climbs.
So you can see from these figures (admittedly a low number of
samples) that it does pay to tweak the mixture, and even if flown
LOP, the speed is not too bad.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 737.3 hrs
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying
Message 2
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| Subject: | Re: ROP versus LOP...might be off-topic for some |
Good Evening Noel,
Could you define what you mean by "pulling power".
Continental Motors generally suggests that lean side operations be
restricted to sixty-five percent of maximum rated power. Lycoming generally uses
a
figure of seventy-five percent for the same purpose. Both manufacturers
have a considerable number of restrictions as to when and how to run lean.
There are many text books that delve into lean side operations.
Curtiss Wright Corporation has given us about the most extensive guidance I
have ever seen as to the "How Too's" of large radial engines.
Advanced Pilot Seminars of Ada, Oklahoma, teach a course of engine
management which uses Continental, Lycoming and Curtiss Wright data to teach what
really is happening at various power settings.
At very high power settings, (above sixty-five to seventy-five percent of
maximum continuous horsepower)extra fuel is used by most aircraft engine
manufacturers to move the peak cylinder pressures to a point where adequate
cooling can be provided.
That data correlates well with data given by both Lycoming and Continental.
When does your training say that lean side operation is acceptable?
Happy Skies,
Old Bob
In a message dated 8/24/2009 10:18:24 P.M. Central Daylight Time,
noelloveys@yahoo.ca writes:
--> JabiruEngine-List message posted by: "Noel Loveys"
<noelloveys@yahoo.ca>
Lynn:
For what it's worth my training told me that LOP is ok as long as you are
not drawing any power. If you are in a situation where power has to be
pulled you are better off at ROP. If you are constantly running LOP keep
a
close eye on the top of your pistons.
Noel
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: Saturday, August 15, 2009 3:45 PM
jabiruengine-list@matronics.com
Subject: JabiruEngine-List: ROP versus LOP...might be off-topic for some
--> JabiruEngine-List message posted by: Lynn Matteson <lynnmatt@jps.net>
Over the last week, I've had some fun making some tests with my newly-
installed Rotec TBI-40 mixture-adjustable, carburetor-replacement
device on my Jabiru engine. I don't know whether two of these units
will work on a Rotax, so many of you might want to hit the delete key
right now.
For the most part, I was flying it LOP (lean-of-peak), but yesterday
I made a flight and decided that I would try ROP (rich-of-peak). In
flying LOP, the articles I've read say to keep the power requirements
low, and LOP will work and you won't burn the engine down. I was
amazed that this LOP thing even works at all, let alone work as well
as I've found that it seems too....I guess I'm still a bit of a
skeptic. After all, if going lean is a bad thing, how can going even
leaner be a good thing? I won't argue whether or not it's a good or
bad thing, and there are those of you that may not be able to do any
leaning at all, as I was until I got this unit.
Three days ago, I made two trips totaling 475 miles, using LOP
settings, and yesterday I made a 310-mile trip, using ROP settings. I
had flown the 475 miles leaning out the engine until peak EGT, then
leaning more until the engine was obviously low on power, and I
contentedly flew at this setting, watching the scenery crawl by.
Yesterday I decided to actually GO somewhere, and never mind the fuel
saving, I just wanted to get there, so I decided to try ROP.
Here are the average numbers from those trips:
LOP: 27.77 miles per gallon; 3.3 gallons per hour; 93.14
miles per hour
ROP: 23.66 miles per gallon; 4.37 gallons per hour; 103.3 miles per
hour
Altitudes on all of these flight were anywhere from 3000' MSL (with a
base of 1000') to 10,000 MSL, with throttle settings from 2600 rpm to
3050. Fuel flow as seen on the gauge, ranged from 2.5 gallons per
hour to 5.0 not including takeoffs, but including climbs.
So you can see from these figures (admittedly a low number of
samples) that it does pay to tweak the mixture, and even if flown
LOP, the speed is not too bad.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 737.3 hrs
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying
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