MONTY THE ANSWER
MAN ARCHIVE
Swift
Continental C125/C145/O-300 Operational Information
C-145 POWER SETTINGS...
From: "Mark R. Fischer" (75612.2736@compuserve.com)
Subject: Engine operations
I have recently been blessed with 80787, SN 190. She is an absolute delight
to fly and look at. I have been learning as I go through reading the Swift
Foundation materials and talking with folks who have flown swifts, but
I have some specific concerns regarding power settings that I hope you
or someone you know may help me with. I have a C-145 and a fixed pitch
prop. I also have a manifold pressure gauge. From reading bits and pieces
from the electronic and printed newsletters, I understand that I may need
to use reduces power settings so as not to exceed certain limitations.
The airplane was also marked with redlines on the tach at 2350, and on
the MP gauge. I have been taking off with full power of course, and reducing
to 25-25 for climb, and then pulling back to 23" for cruise. At these
power settings, I am always above 2350 RPM - especially in cruise. I checked
the Continental engine manual, and it indicates a redline of 2550 RPM
for the engine.
Am I going to blow-up my
engine operating it this way? If I pull the power back to keep the rpm
below 2350 I plod along at 110 mph, and I can't believe that I should
be doing partial power take offs. Any sage advise you can offer would
be greatly appreciated. -- Mark Fischer
Mark,
The red line for a C-145/O-300 is 2700 rpm, the C-125 red line is 2550.
(that was with the "light" case, I believe with the "heavy" case it should
be 2700 rpm also, but no one ever bothered to get it changed. The reduced
rpm for the 145 series engines is a paperwork technicality. To get the
STC with a minimum of fuss, they just de-rate the engine to 125 hp. 2700
rpm won't hurt a 145!
The only thing that will
hurt these engines is excess heat. The cylinder design is not the best.
The "lower end" of these engines is near "bullet proof" and is almost
identical to the 210 hp IO-360. I cruise my Swift at 24" x 2600
if I'm in a hurry. (about 80% power) that is 116 hp according to the power
chart, well below 125 hp. -- Jim
Guest Answer Man Steve Wilson
(SteveWlson@aol.com) also responded to Mark's email...
Mark...
With a fixed pitch prop you will never pull more than 125 hp (not even
close) from your 145 hp engine. The placard is part of the STC and is
required, but who ever did the math, should have made a power chart which
would become part of the operator's manual and make it easier to see exactly
what power you are pulling. Best advice is, "Be happy. Don't worry." Every
engine has a "sweet spot" where it likes to cruise. Below that power setting,
it is not making the best power and you are not getting the cruise you
should. Above that power setting, it is wasting fuel and not getting a
corresponding increase in airspeed. Sometimes you can see it as an increase
in temps with little or no increase in airspeed. Heat is a killer on the
small TCM Engines. My setup right now has a "sweet spot" at about 2475
to 2500 RPM. I am about to switch to another prop (from 59" pitch to 62"
pitch). If I figured it right and encounter a little luck on the way maybe
the "sweet spot" will move up about 100 RPM (which would be ideal). If
it works, I should be able to move up a few knots with only a little or
no increase in fuel burn. It's kinda like putting your car in overdrive.
All the best with N80787. As you are finding out, there's nothing quite
like a Swift!!!
O-300 CHT AND RPM...
(12399)
From: Ed Lloyd <edlloydaustin@juno.com>
Subject: O300D Operation
Jim,
Got a question for you. After a recent flight in 56K, I was visiting with
Duane and Dorothy Golding and just shooting the breeze. I mentioned that
my CHT peaked at about 190 during a climb. After pulling power back the
temp lowers maybe 10 degrees or so. They felt the gauge was in error and
indicating low. I have an Alcor ET gauge also. When I am lean of peak,
the CHT will rise above the 190-200 range, and then settle down to operate
at just below 200 degrees on the CHT that's coupled to this engine. Can
you shed any light on the CHT being low or high or ok as it is? RPM at
cruise 2550. With the prop I have, at WOT, the RPM in level flight will
go 2650 to 2700 RPM. This is a heavy case engine also. Thanks......Ed
Lloyd
Ed,
190 may be a little low, my CHT runs 210 normally. Back in the "old days,"
before EGT, they leaned the Stratocruisers and DC-7's by CHT, and I would
expect to see just what you're reporting. Your gauge may be reading a
little low, but so what? Just learn what it usually indicates and don't
get uptight unless it changes from what's usual. Level flight RPM of 2650
to 2700 RPM is normal, mine will go to 2800, but I have a McCauley 7359
prop. -- Jim
O-300 PERFORMANCE...
(080600)
Subj: Engine RPM and performance
From: Mark Kadrich <starwizz@ricochet.net>
Hi Monty,
I've just gotten back from the Evergreen fly-in and after doing the 1200
mile round trip a question popped into my mind: What is the maximum RPM
for a Continental 0-300C with 1500 hours? The reason I ask is that I cruised
at 135 indicated (sorry, no GPS yet :-) and I tach'ed 2600 RPM at 3500'.
(This is my normal 'putting around the patch' altitude. We cruised between
4500 and 7500 and the view was fantastic.) My tach says that 2700 is max.
Is this correct? Not that I want to stress the engine, but it is nice
to know what the limits are. The manual is confusing me. It would seem
that the gating factor is the manifold pressure? Thanx for the time, Mark,
3243K
Mark,
The type certificate and the operators manual say 2700 rpm max. If the
engine is worn, perhaps it might be prudent to baby it a little, but 2700
is the red line. If you want to be a clubhouse lawyer, you can find several
references to higher rpm than 2700. The altitude performance curve in
the operators manual shows manifold pressure of slightly over 28" and
2800 rpm. In prop certification, the engine can turn 110% red line rpm
with the throttle closed when dived to red line airspeed. (2970 rpm) Horsepower
(BMEP) is a cross section of rpm and manifold pressure. If you follow
the curves on the power chart, you can determine the percentage of power
you are using. With a fixed pitch prop, you are somewhat limited in the
combinations of rpm and manifold pressure you can obtain, but by observing
what comes up for different throttle settings, you can determine the percentage
of power you are using. The O-300 is what might be called a "48" engine.
In other words, a combination of rpm and manifold pressure that equals
48 is 75% power. For example, 24" mp x 24(00) rpm = 75%. Other 75% settings
might be 23" x 2500, 22" x 2600 or 21 x 2700 rpm. Other power settings
can be determined by consulting the chart. -- Jim
RED LINE??? WHAT RED
LINE... (090100)
Subj: Max RPM
From: Tom Taylor <tataylor@homemail.com>
Jim,
Just out of curiosity.... In looking over the reply you gave Mark Kadrich
about the max rpm to be turned by an O-300 Swift, I noticed you made reference
to the RPM limitations in the type certificate (engine, I presume) and
operator's manual. However, doesn't the Swift STC for the O-300 limit
RPM to 2270 (sea level) and 125 HP? Of course, everybody ignores this
(I'm not admitting anything!), so that on a practical level, I think your
advice was quite correct for the O-300 engine... but, isn't it true that
the tach should carry a redline for 125 HP? Or, are some of the other
O-300 STC's more liberal than the ones I have seen? -- TAT
Tom,
The Swift Association STC (old Piedmont) limits the engine to 125 hp.
(Most others do also) 125 hp is 86% power for a 145 hp engine. Whoever
wrote up the STC should have written it that way, but they didn't. Instead,
they simply said, "Do not exceed 2270 rpm at any time". What they left
unsaid was, "at full throttle at sea level manifold pressure". There are
plenty of alternate power settings for 125 hp. For instance, 2700 rpm
and 25" = 125 hp. 2600 rpm and 26" = 125 hp. 2500 rpm and 27" = 125 hp.
2400 rpm and 28" =125 hp. 2300 rpm and 29" = 125 hp and yes, 2270 rpm
and full throttle, at sea level manifold pressure = 125 hp. (this assumes
a little over 29" HG @ sea level.) The STC requires a placard, "do not
exceed 2270 rpm at any time", but the tach should be red lined at 2700
rpm. I have applied for an STC to use the Sensenich 74DR prop on the Swift
and have worded it accordingly. I wouldn't get caught up in legalese interpreting
wording on that old STC.
The 150 Lycoming engine
installation in a Swift has a similar 125 hp restriction. The placard
requirement is much more sensible: PLACARD FOR LYCOMING O-320 ENGINE :
"To avoid exceeding the 125 hp limitation of the Lycoming O-320 engine
at 2700 rpm A straight line variation of manifold pressure from 25" HG
at sea level to 23" HG at 5,000 feet altitude must be observed". (I don't
think this placard is quite right either, but it is on the right track.)
At any altitude 24" x 2700 rpm should equal about 125 hp. (the O-320 has
a slightly different characteristic than the O-300, due to a slightly
higher compression ratio. Remember I said an O-300 is a "48" engine? (rpm
x mp = 48 = 75% power) The 150 Lycoming is a "47" engine. -- Jim
O300-A TEMPS... (090200)
Subj: Cooling
From: Dennis Friedrich <dennisd@crcwnet.com>
Just got my 300A installed and took it up for the first time today. The
temp is running 375 degrees or so. Never over 400 however. Is that the
normal temp? Looks like certain portions of the cylinder get hotter than
others as indicated by the discolored paint. Just want to make certain
that it is cooling fine. Don't want to crack a new mil. cylinder. Also
am told that I should run it at 2600 for a few hours. What about the mixture
while breaking in the new TOP overhaul? Thanks.
Dennis,
375 is fine! Redline is 525. Don't lean the mixture while running in an
engine. 2,600 will probably be OK, as long as the manifold pressure is
not too high. I say probably because I don't know how your cylinder walls
were prepared. If the cylinders were finished to an RMS of 35 to 45 (factory
spec) 2,600 rpm will be OK, if the cylinders are rougher than that it
may be necessary to "slow time" the engine to avoid wearing out rings
in just a few hours. -- Jim
145HP SWIFT INFORMATION...(120500)
Subj: General
From: Robert Carver <rcarve@earthlink.net>
If I'm looking at a Swift that is powered by a 145, what kind of cruise
speed and fuel burn would it have? Also, if adding a fuselage fuel tank
of 10 gal. for additional range, would it be necessary or even a good
idea to get the weight increase? Adding more fuel will cut down the passenger
+ baggage that can be carried, which seems to be defeating the purpose
of using the a/c for cross country flights without landing every hour
and a half for gas. What have most folks done to make their Swifts so
powered to be a better x-c plane? Maybe they fly their 182's when they
go somewhere? Thanks for the answer, if there is one. Although I'm not
presently an owner, I enjoy your "answerman" input in the weekly
email. Bob
Bob,
For many years I flew a 145 Swift with no aux. fuel and very rarely thought
I needed any. I planned x-c flights for 3 hours, burning 7 - 8 gph and
a fill usually took 21 - 25 gallons. My par speed for a 10 year period
was 125 mph when throttled back and leaned out, 140 mph average and 150
mph when I was in a hurry. With a tailwind, I would throttle back and
burn about 6 gph. At 6 gph, 28 gallons (which a Swift actually holds,
despite the 26 gal. capacity marked on the fuel cap) is good for 4 hours
plus reserve. At 150 mph consumption is 9.5 gph so I planned on 2 1/2
hour legs. The Swift I have now holds 37 gallons and is good for more
endurance than I am! Due to health problems I no longer fly cross country.
It seems everyone needs 50 gallons of fuel these days. A Swift flys a
lot nicer when the empty weight is below 1200 pounds and of course the
normal gross weight is 1710 pounds. Mark Holliday flys his 210 hp Swift
to California and Florida and points between with standard fuel. -- Jim
STATIC RPM... (JAN 03)
Subj: Max RPM
From: Bob Price <BobPriceSwift@aol.com>
Jim: During the runup yesterday the engine checked out great at 50 RPM
Mag Drop both L and R... After warmup I set the brakes and ran the engine
up to max RPM and could only get 2150... Is this normal? I have a McCauley
Prop DM7357... Thanks Jim......... Bob >>
Bob
If you look at the Swift Type Certificate, (available for viewing on the
Swift site) you will see the static rpm limits are not over 2050 not under
1950. So you are actually a little high! Now don't worry about it, your
tach may be off a little and the wind may have contributed to what you
saw. Also, a 73x55 prop allows static rpm up, to 2180 which does not make
much sense to me but that is what it says. -- Jim
TEMPS... (DEC 03)
Subj: Cyl head/oil temps
From: Harry Fenton <gippsaero@charter.net>
Hi Jim,
I'm kind of curious about the engine temperatures that I'm seeing. The
CHT is running about 485-500F with our ambient winter temps of 25-30F
and the oil temp is running about 120-130F. I felt that the oil temp was
a bit low and I blocked off the air intake to the oil cooler and it now
runs about 165F. I've been messing around with baffling, but the CHT consistently
runs on the high side. I've checked the oil temp probe for accuracy and
it is pretty close. I've used an infrared thermometer to compare cylinder
surface temps with the CHT gauge and they are pretty close, too. I don't
have much experience with the C125 engines, so I'm not sure if the numbers
above are within reason, but the cylinder temp just seems to be about
50F on the high side. What do you think? -- Harry
Harry
What kind of cyl head temp gauge are you using? The cheap guages don't
read right at low ambient temps. 500 F is too hot! As I recall, N78267
had a lot of old military surplus instrumentation, maybe the guage is
just old and tired! 500 F = 260 C. I have an O-300A and never read over
210 C. Do you have the thermocouple on the top or bottom plug? I believe
Continental calls for the thermocouple to be on the downstream plug, which
is the upper plug on an updraft cooling system. . -- Jim
MORE TEMPS... (DEC 03)
Subj: Cyl head/oil temps
From: Harry Fenton <gippsaero@charter.net>
The temp indications have been kind of a puzzler. I would think that if
the CHT's were at 500 or 550F that the oil temp would also go off scale,
but the oil temp has been running no higher than 165. Oil pressure is
also very good. When I topped the cylinders the bores were perfectly shiny
like a mirror but the rings and pistons did not show any heat stress.
The previous owner ran the engine on the ground for 20 minutes every couple
of three weeks for three years so I kind of wrote off the glazing due
to this unwise operating practice. Now I'm thinking that the high CHT
may be a contributor. Baffling-wise, the installation is dead stock, and
while the flexible sealing material is old, it doesn't seem to be sealing
all that bad. The upper seal that runs along the edge of the cowling split
is the worst , but there are only a couple of areas where is not riding
sealing completely. During the summer I used duct tape to seal up the
gap between the top baffling and the cowling, but the temps stayed about
the same, indicating about 280-290C(535 to 550F). The indicated temps
were right at redline, but did not go any higher. I've also checked the
mag timing, but the temps ran the same with the old SF series mags as
with the new Slick 6364 mags. The gauge in question is a stand alone dual
CHT gauge of late 40's or 50's vintage. I boiled some water and the gauge
read accurate to that temp. After a flight, I used an infrared surface
temp gauge, bouncing a signal off of the cylinder- the IR gauge indicated
a temp in line with the cockpit gauge The senders connect at a spark plug
gasket, which means that the temp reference is probably about 50F lower
than a bayonet probe would see. The temps are nearly dead even from top
to bottom. The top sender is connected to the rear left cylinder and the
bottom is connected to the bottom right rear cylinder. I haven't been
able to double check the high end temps, but all of my double checks from
about 350F and lower seem to be linear to the cockpit gauge. A reasonable
extrapolation would be that the gauge seems to be accurate. Overall, it
looks like my CHT is too high, which may have contributed to the glazing
condition. So, I'm going to re-do the baffle seal to see if this makes
a change. The gauge is also suspect, so I'm going to rig up another gauge
to see if the numbers fall into the same range. I don't want to pull the
cylinders off again! The biggest puzzler to me is the high CHT vs low
oil temp. High oil temps and low CHT would make sense, but I've almost
always seen high oil temps along with high CHT. Anyway, I'll let you know
what I find. It will probably just boil down to a baffling issue. -- Harry
Harry,
One thing that has always
puzzled me, why is the C-125 cyl head limit higher (550 vs 525) than the
O-300? If your cylinders have lasted for over 50 years the temp must not
be a problem! You might switch the thermocouple to the top side. -- Jim
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