Today's Message Index:
----------------------
1. 02:52 PM - Re: ROP versus LOP...might be off-topic for some (Noel Loveys)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | ROP versus LOP...might be off-topic for some |
I=99m in agreement with much of what you wrote. The 172 I trained
in did cruise at above 75% power. So yes on long cruises I would lean
the engine I also leaned above six thousand feet. Our land
here is basically all sea level except for the plateau where Gander
International is located (400=99). Most of our training was done
at full rich mix. I think I was the only one who leaned for taxiing and
warm up.
In my thinking the best method of leaning is to use EGTs, one on each
cylinder. Electronic engine management systems are great but
I=99m a bit old school and like to be able to keep an eye on
gauges. Case in point is my Subaru Imprezza. The darn check engine
light came on last week It turns out after reading the codes
that I have a heater in my first air fuel ratio sensor burned out. That
causes the car to run waaaay rich when cold but affects little else.
Problem is Subaru in their folly neglected to install any instruments so
if I had a second problem crop up I would have no way of detecting it.
I=99ve borrowed an analyzer which I lay on the seat beside me and
once a trip I shut off the alert light. Darn expensive instrument set!
My pre flight instruction training was as an AME. Not the American one,
the Canadian one, so to clear things up AME here is an Aircraft
Maintenance Engineer. I have formal training in both piston and turbine
engines and a couple of thousand hours operating them not to mention
tearing them down and rebuilding them. I agree that the flight school,
as far as I was concerned took every short cut in the book when it came
to engine management. That was one of the reasons I was so critical of
the plane before I would fly it. I=99m just as glad I
didn=99t get the opportunity to do a 50 hr inspection on that
plane. It may still be grounded. J
Noel
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
BobsV35B@aol.com
Sent: Tuesday, August 25, 2009 5:17 PM
Subject: Re: JabiruEngine-List: ROP versus LOP...might be off-topic for
some
Good Afternoon Noel,
Do you generally cruise above seventy-five percent power?
If so, ROP is probably best unless you have a supercharger. Whole
'nother question.
Do you ever cruise above six thousand feet MSL?
If you do (with a normally aspirated engine) there is no way you could
damage the engine with the mixture control regardless of what you did
with it!
Personally, I find that the vast majority of my flying is done at power
settings where LOP is by FAR the better way to go.
Very few flight training operations have the time or the inclination to
teach proper engine operations for any regime other than the basic
training operation. It is also very rare that any training operation
will have instrumentation installed that will tell the pilot whether or
not the fuel distribution is good enough to allow Lean Side Operations.
Individual airplanes of the same model and same vintage often vary
widely as to fuel distribution. There are methods that can be used to
determine fuel balance, but it gets quite time consuming to do so.
Without good distribution, you can't take advantage of the lean side.
However, once we do have good distribution and lean side operations ARE
practical, the benefits are great.
That is the beauty of a course such as is available from the Advanced
Pilot Seminar folks. It teaches us first how to find out how the
airplane we are flying works. It then tells us how to fix it if
something is wrong.
As Lynn has told us, he was fortunate enough to read most of what John
Deakin has written on the subject.
There are a lot of Old Wives Tales that are taught beginning students
because there is not adequate time in the training syllabus to
completely cover the issue.
If you include normal cross country flight as your definition of
endurance flight and you don't go cross country, I guess you have little
use for Lean Side operation, but I cannot imagine operating in any other
way.
It does take training. There is no quick "cookie cutter" formula to tell
us how to do it, but the benefits in longer engine life, cooler
operations, and cleaner engine operations are worth the effort all by
themselves.
The lower fuel costs and greater range available are just icing on the
cake.
I never flew a piston engine airliner that was NOT operated in some form
of lean side operation. For the short haul airplanes, it was "Auto
Lean'. For long haul, especially when we had the services of a flight
engineer, it was manually leaned well beyond the point of Auto Lean.
We now have the benefit of excellent low cost engine instrumentation to
tell us what Lindbergh had to find out by lengthy bouts of
experimentation, but the results have NOT changed since those days of
long ago.
Leaner is Cooler and Leaner is Better!
I think Lynn is right on the true path to greater knowledge of how to
properly, safely, and efficiently, operate his engine.
Make any sense at all?
Happy Skies,
Old Bob
In a message dated 8/25/2009 1:12:49 P.M. Central Daylight Time,
noelloveys@yahoo.ca writes:
Increasing throttle under load
So basically what I was saying was the same thing as Continental and
Lycoming Stay rich of peak when you need lots of power. Lean
of Peak should be reserved basically for long descents at lower throttle
settings, taxiing or possibly endurance flight.
When I was in flight school the school instructed me to always lean the
engine LOP except for takeoff which we used full throttle for a lot of
the training exercises that was ok but we cruised the C172 at close to
75% throttle. On solo flights I always ran ROP except if I was doing a
long decent of say five minutes or more. Once in the landing circuit I
always went full rich to be ready to draw power for a go around.
Most of the carbs are set up to run the engine a little rich at idle to
make them easier to start. While warming up an engine or taxiing I
usually mixed LOP. Part of the checklist turning onto the runway was to
mix full rich The field was on a plateau 400 ft msl.
A lot of the instructors and students didn=99t use the same fuel
management on the ground as I did and as far as I can see the paid for
it fouled plugs. On one occasion I saw the plane I was about to fly
pull up to the fuel pumps spewing a fair bit of soot from the exhaust.
I called the AME ( Aircraft Maintenance Engineer) lean the idle mixture
a bit. For a week the engine ran great but one student just
couldn=99t get it started after a cold night so they enrichened it
again until we got warmer weather.
I=99m not sure if the flight school wanted to keep me or kill me.
Almost every flight I would find snags in the plane. Low tires, crud
build up on the control hinges and spinner problems were all cleared in
short order. That may have been why they always scheduled me to fly at
daybreak The plane wouldn=99t see and engineer until my
next flight. I also noticed the instructors would stick close to the
other students during their walk around but in my case they only checked
the fuel caps were in place.
Noel
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
BobsV35B@aol.com
Sent: Tuesday, August 25, 2009 1:08 AM
Subject: Re: JabiruEngine-List: 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:
<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
<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:
========================
Use utilities Day
=======================
- MATRONICS WEB FORUMS
=======================
- List Contribution Web Site sp;
_____
http://www.matronics.com/Navigator?JabiruEngine-List
http://forums.matronics.com
http://www.matronics.com/contribution
List
href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.
matronics.com/Navigator?JabiruEngine-List
ms.matronics.com/">http://forums.matronics.com
tp://www.matronics.com/contribution">http://www.matronics.com/contributio
n
_____
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|