Today's Message Index:
----------------------
1. 02:43 AM - AK-14P Carburetor (Richard Goode)
2. 06:02 AM - Re: Cowl design and CHT (Roger Kemp)
3. 12:09 PM - Re: Cowl design and CHT (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
4. 01:23 PM - Re: Cowl design and CHT (Eric Wobschall)
5. 04:22 PM - Re: Cowl design and CHT (RICHARD VOLKER)
6. 04:35 PM - Re: Cowl design and CHT (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
7. 04:48 PM - Re: Cowl design and CHT (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
8. 05:02 PM - Re: Cowl design and CHT (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
9. 05:21 PM - Re: Cowl design and CHT (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
10. 05:31 PM - Re: Cowl design and CHT (Eric Wobschall)
11. 05:34 PM - Re: Cowl design and CHT (Eric Wobschall)
12. 06:41 PM - Re: Cowl design and CHT (Vic)
13. 07:57 PM - Batteries (Thomas Smith)
14. 08:45 PM - Re: Batteries (Roger Kemp M.D.)
Message 1
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| Subject: | AK-14P Carburetor |
I'm certainly not an expert on these carburetors,but would say that:
They are very complex,and sophisticated,but logical to understand.
There are 5 jets in it,3 of which can be changed for different sizes.
This is apart from other adjustments for fuel pressure;idle
needle;metering needle;altitude control etc.!!
The compensating jet [which the Russians call the "suction jet"]affects
ALL power settings above low speed running.
The hesitation that can occur on opening the throttle is caused by the
acceleration jet being wrong-in my experience as often because it dumps
in TOO MUCH fuel [causing a rich cut] rather than too little.
Correctly set,there will be no hesitation.
The M14P is designed to run VERY rich at all working power
settings,simply to keep it cool.We fitted a test engine with a lamda
sensor in the exhaust to get accurate figures for mixture,and it was way
outside the automotive range-ie too rich even to measure with the
instrument!
Very few engines that we see are running as well as they should,which
means no excessive black smoke;no hesitation;very smooth low speed
idle;no hesitation on pick up;running cool at high power settings.
No problem to operate in the yellow sector-the designers were very
conservative and allow 220 degrees continuous,but I would try to keep
under 205/210 for continuous.
Finally,the CHT gauges can be very inacurate-have you checked yours to
see how accurate it actually is???
Richard
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
Message 2
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| Subject: | Re: Cowl design and CHT |
Rick,
I've noticed a difference in the CHT on my 52 with the 18 lip stick spinner vs
my 50 with the skull cap on the V450 two blade. Can't quantify the # of degrees
specifically.
Doc
-----Original Message-----
>From: RICHARD VOLKER <rick@rvairshows.com>
>Sent: Oct 9, 2010 8:50 AM
>To: yak-list@matronics.com
>Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two Sukhois and three
Yak 52's running similar power levels. Sukhois seem to be able to maintain cool
CHT's through any operating condition and duration, with hovering at full power
on a 95 degree day giving green CHT's. The cowl design on the Sukhoi has a
leading edge that is an airfoil, with an inner cowl shape to speed airflow. The
Yak 52 uses a cowl design that is a shell with the same external shape and
no "flying" surface internally to speed airflow. All three of the Yak 52's I have
flown seem to be limited to climbing Vy at max cruise. At any rate, they seem
significantly hotter at much less extreme conditions. Cowl vents on the Sukhoi
are a louver design. On the Yak, the cowl venting is a large opening behind
the cowl. When the Sukhoi Design Bureau added horsepower with the M9R engine,
they added a larger oil cooler and louvers on the side of the cowl that looked
more like rear facing opening of a Yak 52. The
!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip Holm? Skip has
incorporated many of his Reno race speed tricks on this M14P powered aircraft.
The actual airframe design was penned by Sergei Yakovlev. Skip Holm has put
a giant spinner on his Bear 360. He has also devised an added aerodynamic device
placed behind the spinner to further reduce drag (unknown effect on CHT).
Exhausts are flush and aim back into the airflow. The decreased back pressure
has increased power. The exhaust pressure in the backwards direction contribute
to airspeed. I am told that six inches of protruding exhausts give several
knots of speed penalty. Much has been said about CO buildup and exhaust design.
I hope they have done their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing in extreme corners
of the operating envelope with a perceived need to maintain lower cylinder
head temps, should owners develop cowl mods to improve cooling? Has anyone attempted
to build airfoil shapes internal to the existing cowl? Behind the spinner
? I noticed a CHT reduction of an average of 20 degrees going from the Russian
V530 two blade prop without spinner to the three blade MT with large spinner.
Surely there are other mods that could help manage CHT further. Am I alone
in this thought? My contention is that it would be beneficial to be able
to climb at any airspeed above the stall at full power as long as you wish, ala
Sukhoi, without getting into yellow CHT's.
>
>Rick Volker
>
>
>
Message 3
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| Subject: | Cowl design and CHT |
Chris,
I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I have operated
the engine with the spinner off and with the spinner on, and for the one cylinder
in my engine that has a probe stuck in it, the engine ran somewhat cooler
with the spinner attached exactly as you mention. What the other eight were
doing, I have no idea.
That said:
I worked with a gent who put in new higher compression pistons and new cylinders
(on a M-14 engine) and another person who was having very high oil temperature
problems (along with cylinder head temps) on his M-14PF. In both cases, changing
the fuel mixture made a DRAMATIC change in temperatures. I mean, taking
it from borderline RED down into GREEN. The amount of fuel that is dumped into
this engine makes a dramatic change in temps. Spinners can indeed make an
impact, but not nearly as much as fuel.
Another interesting tidbit. One Sukhoi (that I had time watching) got equipped
with a 9 position cylinder head temperature gage (Hubie Tolson). I wish he had
done an exhaustive study (pun intended) but he mainly just wanted to make sure
that he knew what the hottest jug was. What cylinder ran highest temps changed
dramatically from running it on the ground, to running it in the air, which
is logical. As I remember, hottest on the ground was #2. However in the
air it moved around to #4 or #5 ... I am not sure of that, it was awhile ago,
but anyway it tends to show that the Russians had a good idea what they were doing
when they stuck the probe where they did.
Lastly, Richard Goode mentioned that the cylinder head temperature gages we use
are far from being dead nuts calibrated units. I've found that to be true as
well (using a calibrated IR unit by Raytec and also a Thermal IR video unit).
What I found from a sampling of 5 spare probes was fairly consistent readings
between probes, but a big difference between gages. I did not even try to
calibrate mine, but instead just recorded where max temp REALLY was and put a
mark on the gage. We tend to put faith in what a gage is telling us, but that
is really far from true. Comparing cylinder head temps from one aircraft to
another (without first running a calibration check on the instruments you are
using) ends up being very much like comparing apples to oranges.
As an aside, I have only seen one person mess with the jets on these engines, and
interestingly enough it was done exactly like we did on the drag strip. Make
a change, go up and fly it, come back.. talk about it... make another change,
go up and fly it, etc. I doubt if there is any real "standard" on how to mess
with these things other than to have some idea what you are trying to cure
and what adjustment you should start with, something I wish I knew far more about,
but don't.
Mark Bitterlich
________________________________
From: owner-yak-list-server@matronics.com on behalf of Chris Wise
Sent: Sat 10/9/2010 7:06 PM
Subject: Re: Yak-List: Cowl design and CHT
G'Day Richard,
Years ago I belonged to the Waikerie Gliding Club and used to fly the Piper Pawnee
260HP tug.
As I never competed in any big gliding comps I undertook the role as tugmaster.
Now Waikerie can have temps over 40C on some days as the cyl temps would get pretty
hot if not careful.
We found that running a bigger spinner in the summer would significantly reduce
the cyl head temps as the air was possibly directed over the cyl heads more so
than a smaller spinner.
I would imagine that the USA has similar climated conditions as we have here in
Australia.
When flying the 52 or 18T on these hot summer days, one is always aware of the
cyl temps.
The same applies as did the cyl temps on the Pawnee in the summer.
The Yaks with the big spinners run cooler.
Cheers,
Chris
----- Original Message -----
From: Richard Goode <mailto:richard.goode@russianaeros.com>
To: yak-list@matronics.com
Sent: Saturday, October 09, 2010 11:53 PM
Subject: Re: Yak-List: Cowl design and CHT
The main reason that different M14P engines work at different temperatures for
the same sort of flying is that few owners ever bother to change the compensating
jets,and running with smaller jets [which means more fuel] will greatly reduce
CHT.
The M14P runs very rich most of the time with some of the fuel going to cool the
cylinders.
The jets are easy to change [5 minutes with the cowling off];come in a range 1.1to
2.1mm.
In fact it is a good idea to change the jet between summer and winter,to avoid
over-cooling in winter.
Richard
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com <http://www.russianaeros.com/>
----- Original Message -----
From: RICHARD VOLKER <mailto:rick@rvairshows.com>
To: yak-list@matronics.com
Sent: Saturday, October 09, 2010 2:50 PM
Subject: Yak-List: Cowl design and CHT
I have noticed large differences in the CHT temps of two Sukhois and three
Yak 52's running similar power levels. Sukhois seem to be able to maintain cool
CHT's through any operating condition and duration, with hovering at full power
on a 95 degree day giving green CHT's. The cowl design on the Sukhoi has
a leading edge that is an airfoil, with an inner cowl shape to speed airflow.
The Yak 52 uses a cowl design that is a shell with the same external shape and
no "flying" surface internally to speed airflow. All three of the Yak 52's I
have flown seem to be limited to climbing Vy at max cruise. At any rate, they
seem significantly hotter at much less extreme conditions. Cowl vents on the
Sukhoi are a louver design. On the Yak, the cowl venting is a large opening behind
the cowl. When the Sukhoi Design Bureau added horsepower with the M9R engine,
they added a larger oil cooler and louvers on the side of the cowl that
looked more like rear facing opening of a Yak 52. The!
se Russians must talk to each other!
Has anyone seen the BEAR 360 that has been marketed by Skip Holm? Skip has
incorporated many of his Reno race speed tricks on this M14P powered aircraft.
The actual airframe design was penned by Sergei Yakovlev. Skip Holm has put
a giant spinner on his Bear 360. He has also devised an added aerodynamic device
placed behind the spinner to further reduce drag (unknown effect on CHT).
Exhausts are flush and aim back into the airflow. The decreased back pressure
has increased power. The exhaust pressure in the backwards direction contribute
to airspeed. I am told that six inches of protruding exhausts give several
knots of speed penalty. Much has been said about CO buildup and exhaust design.
I hope they have done their homework in that respect.
My question is this: Since more Yak 52 owners are playing in extreme corners
of the operating envelope with a perceived need to maintain lower cylinder
head temps, should owners develop cowl mods to improve cooling? Has anyone attempted
to build airfoil shapes internal to the existing cowl? Behind the spinner
? I noticed a CHT reduction of an average of 20 degrees going from the Russian
V530 two blade prop without spinner to the three blade MT with large spinner.
Surely there are other mods that could help manage CHT further. Am I
alone in this thought? My contention is that it would be beneficial to be able
to climb at any airspeed above the stall at full power as long as you wish,
ala Sukhoi, without getting into yellow CHT's.
Rick Volker
p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics========================<; via the Web href="http://forums.matronics.com">http://forums.matronics.com
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Message 4
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| Subject: | Re: Cowl design and CHT |
Mark, when you say the fuel mixture increase made a big difference, do
you mean the click-stop adjustment on the back of the carburetor?
On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Chris,
>
> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I
> have operated the engine with the spinner off and with the spinner
> on, and for the one cylinder in my engine that has a probe stuck in
> it, the engine ran somewhat cooler with the spinner attached exactly
> as you mention. What the other eight were doing, I have no idea.
>
> That said:
>
> I worked with a gent who put in new higher compression pistons and
> new cylinders (on a M-14 engine) and another person who was having
> very high oil temperature problems (along with cylinder head temps)
> on his M-14PF. In both cases, changing the fuel mixture made a
> DRAMATIC change in temperatures. I mean, taking it from borderline
> RED down into GREEN. The amount of fuel that is dumped into this
> engine makes a dramatic change in temps. Spinners can indeed make
> an impact, but not nearly as much as fuel.
>
> Another interesting tidbit. One Sukhoi (that I had time watching)
> got equipped with a 9 position cylinder head temperature gage (Hubie
> Tolson). I wish he had done an exhaustive study (pun intended) but
> he mainly just wanted to make sure that he knew what the hottest jug
> was. What cylinder ran highest temps changed dramatically from
> running it on the ground, to running it in the air, which is
> logical. As I remember, hottest on the ground was #2. However in
> the air it moved around to #4 or #5 ... I am not sure of that, it
> was awhile ago, but anyway it tends to show that the Russians had a
> good idea what they were doing when they stuck the probe where they
> did.
>
> Lastly, Richard Goode mentioned that the cylinder head temperature
> gages we use are far from being dead nuts calibrated units. I've
> found that to be true as well (using a calibrated IR unit by Raytec
> and also a Thermal IR video unit). What I found from a sampling of
> 5 spare probes was fairly consistent readings between probes, but a
> big difference between gages. I did not even try to calibrate
> mine, but instead just recorded where max temp REALLY was and put a
> mark on the gage. We tend to put faith in what a gage is telling
> us, but that is really far from true. Comparing cylinder head temps
> from one aircraft to another (without first running a calibration
> check on the instruments you are using) ends up being very much like
> comparing apples to oranges.
>
> As an aside, I have only seen one person mess with the jets on these
> engines, and interestingly enough it was done exactly like we did on
> the drag strip. Make a change, go up and fly it, come back.. talk
> about it... make another change, go up and fly it, etc. I doubt if
> there is any real "standard" on how to mess with these things other
> than to have some idea what you are trying to cure and what
> adjustment you should start with, something I wish I knew far more
> about, but don't.
>
> Mark Bitterlich
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
> Sent: Sat 10/9/2010 7:06 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> G'Day Richard,
>
> Years ago I belonged to the Waikerie Gliding Club and used to fly
> the Piper Pawnee 260HP tug.
> As I never competed in any big gliding comps I undertook the role as
> tugmaster.
> Now Waikerie can have temps over 40C on some days as the cyl temps
> would get pretty hot if not careful.
> We found that running a bigger spinner in the summer would
> significantly reduce the cyl head temps as the air was possibly
> directed over the cyl heads more so than a smaller spinner.
>
> I would imagine that the USA has similar climated conditions as we
> have here in Australia.
> When flying the 52 or 18T on these hot summer days, one is always
> aware of the cyl temps.
> The same applies as did the cyl temps on the Pawnee in the summer.
> The Yaks with the big spinners run cooler.
>
> Cheers,
> Chris
>
>
> ----- Original Message -----
> From: Richard Goode <mailto:richard.goode@russianaeros.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 11:53 PM
> Subject: Re: Yak-List: Cowl design and CHT
>
> The main reason that different M14P engines work at different
> temperatures for the same sort of flying is that few owners ever
> bother to change the compensating jets,and running with smaller jets
> [which means more fuel] will greatly reduce CHT.
> The M14P runs very rich most of the time with some of the fuel
> going to cool the cylinders.
> The jets are easy to change [5 minutes with the cowling off];come
> in a range 1.1to 2.1mm.
> In fact it is a good idea to change the jet between summer and
> winter,to avoid over-cooling in winter.
> Richard
>
> Richard Goode Aerobatics
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
> United Kingdom
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com <http://www.russianaeros.com/>
>
>
> ----- Original Message -----
> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 2:50 PM
> Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two
> Sukhois and three Yak 52's running similar power levels. Sukhois
> seem to be able to maintain cool CHT's through any operating
> condition and duration, with hovering at full power on a 95 degree
> day giving green CHT's. The cowl design on the Sukhoi has a leading
> edge that is an airfoil, with an inner cowl shape to speed airflow.
> The Yak 52 uses a cowl design that is a shell with the same external
> shape and no "flying" surface internally to speed airflow. All three
> of the Yak 52's I have flown seem to be limited to climbing Vy at
> max cruise. At any rate, they seem significantly hotter at much less
> extreme conditions. Cowl vents on the Sukhoi are a louver design.
> On the Yak, the cowl venting is a large opening behind the cowl.
> When the Sukhoi Design Bureau added horsepower with the M9R engine,
> they added a larger oil cooler and louvers on the side of the cowl
> that looked more like rear facing opening of a Yak 52. T!
> he!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip
> Holm? Skip has incorporated many of his Reno race speed tricks on
> this M14P powered aircraft. The actual airframe design was penned
> by Sergei Yakovlev. Skip Holm has put a giant spinner on his Bear
> 360. He has also devised an added aerodynamic device placed behind
> the spinner to further reduce drag (unknown effect on CHT). Exhausts
> are flush and aim back into the airflow. The decreased back
> pressure has increased power. The exhaust pressure in the backwards
> direction contribute to airspeed. I am told that six inches of
> protruding exhausts give several knots of speed penalty. Much has
> been said about CO buildup and exhaust design. I hope they have done
> their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing in
> extreme corners of the operating envelope with a perceived need to
> maintain lower cylinder head temps, should owners develop cowl mods
> to improve cooling? Has anyone attempted to build airfoil shapes
> internal to the existing cowl? Behind the spinner ? I noticed a CHT
> reduction of an average of 20 degrees going from the Russian V530
> two blade prop without spinner to the three blade MT with large
> spinner. Surely there are other mods that could help manage CHT
> further. Am I alone in this thought? My contention is that it would
> be beneficial to be able to climb at any airspeed above the stall at
> full power as long as you wish, ala Sukhoi, without getting into
> yellow CHT's.
>
> Rick Volker
> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List
> ">http://www.matronics========================<; via the Web
> href="http://forums.matronics.com">http://forums.matronics.com
> _p; generous bsp; href="http://www.matronics.com/contribution
> ">http://www.matronics.com/c================
>
>
>
>
> -----------------------------------------------
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> dangerous content by the Invictawiz MailScanner
> and is believed to be clean.
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>
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>
>
> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
> href="http://forums.matronics.com">http://forums.matronics.com
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Message 5
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| Subject: | Re: Cowl design and CHT |
Mark,
I use a JPI engine analyzer on my SU26. On the ground, they are all within 10
degrees of each other- almost equal. In the air, #2 is the hottest, followed
very closely by #1, then #9. The coolest cylinder is #4 (master cylinder),
followed closely by #5. EGT is interesting: The closest spread that I get is
about 70 degrees. 80 degrees for economy cruise. 110 for max cruise. The worst
in flight is 150 degrees diff. at full power. I can run it up at 65% rpm on
the ground and it will take about 20 sec after a long taxi (250 degrees EGT diff
meaning loaded up plugs) to get to a low of 110 degrees diff. That is when
I shut down, assuming plugs are all cleared. I have run two M14P engines on
this JPI monitor and have seen the same profile on each. The EGT diff is normal
for a carbureted engine. The #7 cylinder has very low EGT and is responsible
for most of the differential. Initially on the last engine, I thought this might
be due to some problems with the cylinder and compression was a little lower
than the rest on a high time engine, I replaced it. The new cylinder had the
same low EGT. My new M14P engine again has the same profile. I am kicking myself
for wasting the new cylinder on what is likely the position of the probe
on the #7 exhaust stack, or the shape of the exhaust stack, or that the fuel happens
to sling into this cylinder more( the engine monitor suggests this) on
every engine. All in, you can second guess these things a bit too much. I have
fun keeping all cylinders from getting too cool on descents. I get to watch
the shock cooling alert when I do gyroscopic or severely yawed maneuvers, as
air flow gets rerouted. Flying inverted brings the coolest cylinders up in temp
and the previously hottest cylinders down. The only reason to use the EGT
on this motor would be to diagnose cylinder problems, or to back up ignition
timing. I have been told that Swift fuel has a delayed burn, requires about
a 3 degree advance of timing with corresponding EGT rise to get 100% power. Leaving
tim!
ing stoc
k gives about 97% power but 15 % more range from the same fuel volume. I have
seen an improperly timed M14P crack rings on every cylinder. I will bet this would
have showed on the EGT if the pilot had a similar JPI and knew what to expect.
The JPI probes test accurately.
My old SU29 had the pilot in command panel CHT on #2 cylinder and the passenger
panel CHT on #4. This could be viewed with a little leaning around the head
of the passenger, giving all the info you need. I always thought the poor man's
engine monitor would be an extra Russian CHT on this #4 cylinder- it takes
up very little space and they are plentiful on the used market. If anyone likes,
I will send the JPI monitor profile of the air show I did in 95 degree F
weather. it is a ground start with complete warm up and ground start for the
routine. It carries on for 8 minutes at full manifold pressure and 99% rpm, then
power is reduced with a landing one minute later.
Rick Volker
www.rvairshows,com
On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
wrote:
>
> Chris,
>
> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I have operated
the engine with the spinner off and with the spinner on, and for the one cylinder
in my engine that has a probe stuck in it, the engine ran somewhat cooler
with the spinner attached exactly as you mention. What the other eight were
doing, I have no idea.
>
> That said:
>
> I worked with a gent who put in new higher compression pistons and new cylinders
(on a M-14 engine) and another person who was having very high oil temperature
problems (along with cylinder head temps) on his M-14PF. In both cases,
changing the fuel mixture made a DRAMATIC change in temperatures. I mean, taking
it from borderline RED down into GREEN. The amount of fuel that is dumped
into this engine makes a dramatic change in temps. Spinners can indeed make
an impact, but not nearly as much as fuel.
>
> Another interesting tidbit. One Sukhoi (that I had time watching) got equipped
with a 9 position cylinder head temperature gage (Hubie Tolson). I wish he
had done an exhaustive study (pun intended) but he mainly just wanted to make
sure that he knew what the hottest jug was. What cylinder ran highest temps
changed dramatically from running it on the ground, to running it in the air,
which is logical. As I remember, hottest on the ground was #2. However in the
air it moved around to #4 or #5 ... I am not sure of that, it was awhile ago,
but anyway it tends to show that the Russians had a good idea what they were
doing when they stuck the probe where they did.
>
> Lastly, Richard Goode mentioned that the cylinder head temperature gages we use
are far from being dead nuts calibrated units. I've found that to be true
as well (using a calibrated IR unit by Raytec and also a Thermal IR video unit).
What I found from a sampling of 5 spare probes was fairly consistent readings
between probes, but a big difference between gages. I did not even try
to calibrate mine, but instead just recorded where max temp REALLY was and put
a mark on the gage. We tend to put faith in what a gage is telling us, but
that is really far from true. Comparing cylinder head temps from one aircraft
to another (without first running a calibration check on the instruments you
are using) ends up being very much like comparing apples to oranges.
>
> As an aside, I have only seen one person mess with the jets on these engines,
and interestingly enough it was done exactly like we did on the drag strip.
Make a change, go up and fly it, come back.. talk about it... make another change,
go up and fly it, etc. I doubt if there is any real "standard" on how to
mess with these things other than to have some idea what you are trying to cure
and what adjustment you should start with, something I wish I knew far more
about, but don't.
>
> Mark Bitterlich
>
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
> Sent: Sat 10/9/2010 7:06 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> G'Day Richard,
>
> Years ago I belonged to the Waikerie Gliding Club and used to fly the Piper Pawnee
260HP tug.
> As I never competed in any big gliding comps I undertook the role as tugmaster.
> Now Waikerie can have temps over 40C on some days as the cyl temps would get
pretty hot if not careful.
> We found that running a bigger spinner in the summer would significantly reduce
the cyl head temps as the air was possibly directed over the cyl heads more
so than a smaller spinner.
>
> I would imagine that the USA has similar climated conditions as we have here
in Australia.
> When flying the 52 or 18T on these hot summer days, one is always aware of the
cyl temps.
> The same applies as did the cyl temps on the Pawnee in the summer.
> The Yaks with the big spinners run cooler.
>
> Cheers,
> Chris
>
>
>
>
> ----- Original Message -----
> From: Richard Goode <mailto:richard.goode@russianaeros.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 11:53 PM
> Subject: Re: Yak-List: Cowl design and CHT
>
> The main reason that different M14P engines work at different temperatures for
the same sort of flying is that few owners ever bother to change the compensating
jets,and running with smaller jets [which means more fuel] will greatly
reduce CHT.
> The M14P runs very rich most of the time with some of the fuel going to cool
the cylinders.
> The jets are easy to change [5 minutes with the cowling off];come in a range
1.1to 2.1mm.
> In fact it is a good idea to change the jet between summer and winter,to avoid
over-cooling in winter.
> Richard
>
> Richard Goode Aerobatics
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
> United Kingdom
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com <http://www.russianaeros.com/>
>
>
> ----- Original Message -----
> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 2:50 PM
> Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two Sukhois and three
Yak 52's running similar power levels. Sukhois seem to be able to maintain
cool CHT's through any operating condition and duration, with hovering at full
power on a 95 degree day giving green CHT's. The cowl design on the Sukhoi has
a leading edge that is an airfoil, with an inner cowl shape to speed airflow.
The Yak 52 uses a cowl design that is a shell with the same external shape and
no "flying" surface internally to speed airflow. All three of the Yak 52's
I have flown seem to be limited to climbing Vy at max cruise. At any rate, they
seem significantly hotter at much less extreme conditions. Cowl vents on the
Sukhoi are a louver design. On the Yak, the cowl venting is a large opening
behind the cowl. When the Sukhoi Design Bureau added horsepower with the M9R
engine, they added a larger oil cooler and louvers on the side of the cowl that
looked more like rear facing opening of a Yak 52. T!
> he!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip Holm? Skip
has incorporated many of his Reno race speed tricks on this M14P powered aircraft.
The actual airframe design was penned by Sergei Yakovlev. Skip Holm has
put a giant spinner on his Bear 360. He has also devised an added aerodynamic
device placed behind the spinner to further reduce drag (unknown effect on CHT).
Exhausts are flush and aim back into the airflow. The decreased back pressure
has increased power. The exhaust pressure in the backwards direction contribute
to airspeed. I am told that six inches of protruding exhausts give several
knots of speed penalty. Much has been said about CO buildup and exhaust
design. I hope they have done their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing in extreme corners
of the operating envelope with a perceived need to maintain lower cylinder
head temps, should owners develop cowl mods to improve cooling? Has anyone
attempted to build airfoil shapes internal to the existing cowl? Behind the spinner
? I noticed a CHT reduction of an average of 20 degrees going from the
Russian V530 two blade prop without spinner to the three blade MT with large
spinner. Surely there are other mods that could help manage CHT further. Am
I alone in this thought? My contention is that it would be beneficial to be able
to climb at any airspeed above the stall at full power as long as you wish,
ala Sukhoi, without getting into yellow CHT's.
>
> Rick Volker
> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics========================<; via the Web href="http://forums.matronics.com">http://forums.matronics.com
> _p; generous bsp; href="http://www.matronics.com/contribution">http://www.matronics.com/c================
>
>
>
>
> -----------------------------------------------
> This message has been scanned for viruses and
> dangerous content by the Invictawiz MailScanner
> and is believed to be clean.
> http://www.invictawiz.com <http://www.invictawiz.com/>
> -----------------------------------------------
>
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>
>
> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
> href="http://forums.matronics.com">http://forums.matronics.com
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Message 6
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| Subject: | Cowl design and CHT |
No, I am talking about the main mixture jet, which Richard Goode refers to as the
"Compensation Jet". Although yes, I have messed with the one you are talking
about.
Being perfectly clear here Eric, I was just a spectator. I profess no special
knowledge on this darn thing other than:
1. I have seen where adjusting the accelerator pump jet will cure hesitation on
throttle advancement versus just plugging the darn thing, which was the initial
cure until smart people figured out you could buy a jet kit and adjust it
accordingly. I am VERY familiar with this kind of thing because you run into
it a lot adjusting a Holley carb where there are many MANY adjustments for the
amount of fuel you dump in when you move the throttle plates.
2. The main jet or "Compensation Jet" has the ability to dramatically change
fuel mixture in the mid to high range of engine RPM.
I would very much love to hear Richard Goode go into more detail on how he determines
how much change to make based on engine indications. He obviously has
way more experience than I do. I have seen it done ONCE... but it worked, in
a big way.
I would also like to hear Richard tell me how many clicks on the back of the carb
equates to one jet size....if that is the case at all.
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of Eric Wobschall
Sent: Sun 10/10/2010 4:20 PM
Subject: Re: Yak-List: Cowl design and CHT
Mark, when you say the fuel mixture increase made a big difference, do
you mean the click-stop adjustment on the back of the carburetor?
On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Chris,
>
> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I
> have operated the engine with the spinner off and with the spinner
> on, and for the one cylinder in my engine that has a probe stuck in
> it, the engine ran somewhat cooler with the spinner attached exactly
> as you mention. What the other eight were doing, I have no idea.
>
> That said:
>
> I worked with a gent who put in new higher compression pistons and
> new cylinders (on a M-14 engine) and another person who was having
> very high oil temperature problems (along with cylinder head temps)
> on his M-14PF. In both cases, changing the fuel mixture made a
> DRAMATIC change in temperatures. I mean, taking it from borderline
> RED down into GREEN. The amount of fuel that is dumped into this
> engine makes a dramatic change in temps. Spinners can indeed make
> an impact, but not nearly as much as fuel.
>
> Another interesting tidbit. One Sukhoi (that I had time watching)
> got equipped with a 9 position cylinder head temperature gage (Hubie
> Tolson). I wish he had done an exhaustive study (pun intended) but
> he mainly just wanted to make sure that he knew what the hottest jug
> was. What cylinder ran highest temps changed dramatically from
> running it on the ground, to running it in the air, which is
> logical. As I remember, hottest on the ground was #2. However in
> the air it moved around to #4 or #5 ... I am not sure of that, it
> was awhile ago, but anyway it tends to show that the Russians had a
> good idea what they were doing when they stuck the probe where they
> did.
>
> Lastly, Richard Goode mentioned that the cylinder head temperature
> gages we use are far from being dead nuts calibrated units. I've
> found that to be true as well (using a calibrated IR unit by Raytec
> and also a Thermal IR video unit). What I found from a sampling of
> 5 spare probes was fairly consistent readings between probes, but a
> big difference between gages. I did not even try to calibrate
> mine, but instead just recorded where max temp REALLY was and put a
> mark on the gage. We tend to put faith in what a gage is telling
> us, but that is really far from true. Comparing cylinder head temps
> from one aircraft to another (without first running a calibration
> check on the instruments you are using) ends up being very much like
> comparing apples to oranges.
>
> As an aside, I have only seen one person mess with the jets on these
> engines, and interestingly enough it was done exactly like we did on
> the drag strip. Make a change, go up and fly it, come back.. talk
> about it... make another change, go up and fly it, etc. I doubt if
> there is any real "standard" on how to mess with these things other
> than to have some idea what you are trying to cure and what
> adjustment you should start with, something I wish I knew far more
> about, but don't.
>
> Mark Bitterlich
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
> Sent: Sat 10/9/2010 7:06 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> G'Day Richard,
>
> Years ago I belonged to the Waikerie Gliding Club and used to fly
> the Piper Pawnee 260HP tug.
> As I never competed in any big gliding comps I undertook the role as
> tugmaster.
> Now Waikerie can have temps over 40C on some days as the cyl temps
> would get pretty hot if not careful.
> We found that running a bigger spinner in the summer would
> significantly reduce the cyl head temps as the air was possibly
> directed over the cyl heads more so than a smaller spinner.
>
> I would imagine that the USA has similar climated conditions as we
> have here in Australia.
> When flying the 52 or 18T on these hot summer days, one is always
> aware of the cyl temps.
> The same applies as did the cyl temps on the Pawnee in the summer.
> The Yaks with the big spinners run cooler.
>
> Cheers,
> Chris
>
>
> ----- Original Message -----
> From: Richard Goode <mailto:richard.goode@russianaeros.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 11:53 PM
> Subject: Re: Yak-List: Cowl design and CHT
>
> The main reason that different M14P engines work at different
> temperatures for the same sort of flying is that few owners ever
> bother to change the compensating jets,and running with smaller jets
> [which means more fuel] will greatly reduce CHT.
> The M14P runs very rich most of the time with some of the fuel
> going to cool the cylinders.
> The jets are easy to change [5 minutes with the cowling off];come
> in a range 1.1to 2.1mm.
> In fact it is a good idea to change the jet between summer and
> winter,to avoid over-cooling in winter.
> Richard
>
> Richard Goode Aerobatics
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
> United Kingdom
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com <http://www.russianaeros.com/>
>
>
> ----- Original Message -----
> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 2:50 PM
> Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two
> Sukhois and three Yak 52's running similar power levels. Sukhois
> seem to be able to maintain cool CHT's through any operating
> condition and duration, with hovering at full power on a 95 degree
> day giving green CHT's. The cowl design on the Sukhoi has a leading
> edge that is an airfoil, with an inner cowl shape to speed airflow.
> The Yak 52 uses a cowl design that is a shell with the same external
> shape and no "flying" surface internally to speed airflow. All three
> of the Yak 52's I have flown seem to be limited to climbing Vy at
> max cruise. At any rate, they seem significantly hotter at much less
> extreme conditions. Cowl vents on the Sukhoi are a louver design.
> On the Yak, the cowl venting is a large opening behind the cowl.
> When the Sukhoi Design Bureau added horsepower with the M9R engine,
> they added a larger oil cooler and louvers on the side of the cowl
> that looked more like rear facing opening of a Yak 52. T!
> he!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip
> Holm? Skip has incorporated many of his Reno race speed tricks on
> this M14P powered aircraft. The actual airframe design was penned
> by Sergei Yakovlev. Skip Holm has put a giant spinner on his Bear
> 360. He has also devised an added aerodynamic device placed behind
> the spinner to further reduce drag (unknown effect on CHT). Exhausts
> are flush and aim back into the airflow. The decreased back
> pressure has increased power. The exhaust pressure in the backwards
> direction contribute to airspeed. I am told that six inches of
> protruding exhausts give several knots of speed penalty. Much has
> been said about CO buildup and exhaust design. I hope they have done
> their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing
in
> extreme corners of the operating envelope with a perceived need to
> maintain lower cylinder head temps, should owners develop cowl mods
> to improve cooling? Has anyone attempted to build airfoil shapes
> internal to the existing cowl? Behind the spinner ? I noticed a CHT
> reduction of an average of 20 degrees going from the Russian V530
> two blade prop without spinner to the three blade MT with large
> spinner. Surely there are other mods that could help manage CHT
> further. Am I alone in this thought? My contention is that it would
> be beneficial to be able to climb at any airspeed above the stall at
> full power as long as you wish, ala Sukhoi, without getting into
> yellow CHT's.
>
> Rick Volker
> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List
> ">http://www.matronics======================== <http://www.matronics========================/> <; via the Web
> href="http://forums.matronics.com <http://forums.matronics.com/> ">http://forums.matronics.com <http://forums.matronics.com/>
> _p; generous bsp; href="http://www.matronics.com/contribution
> ">http://www.matronics.com/c================
>
>
>
>
> -----------------------------------------------
> This message has been scanned for viruses and
> dangerous content by the Invictawiz MailScanner
> and is believed to be clean.
> http://www.invictawiz.com <http://www.invictawiz.com/> <http://www.invictawiz.com/>
> -----------------------------------------------
>
>
>
>
> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
> href="http://forums.matronics.com <http://forums.matronics.com/> ">http://forums.matronics.com <http://forums.matronics.com/>
> href="http://www.matronics.com/contribution">http://www.matronics.com/c
>
>
>
Message 7
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| Subject: | Cowl design and CHT |
Actually, I have no idea how to do what Richard was saying. I watched a gent with
a handful of parts mess with the darn thing and in the end the EGT and Cylinder
Head temps along with oil temps changed dramatically.
I really just do not fully understand this pressure carb.
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of Bitterlich, Mark G CIV Det
Cherry Point, MALS-14 64E
Sent: Sun 10/10/2010 7:32 PM
Subject: RE: Yak-List: Cowl design and CHT
No, I am talking about the main mixture jet, which Richard Goode refers to as the
"Compensation Jet". Although yes, I have messed with the one you are talking
about.
Being perfectly clear here Eric, I was just a spectator. I profess no special
knowledge on this darn thing other than:
1. I have seen where adjusting the accelerator pump jet will cure hesitation on
throttle advancement versus just plugging the darn thing, which was the initial
cure until smart people figured out you could buy a jet kit and adjust it
accordingly. I am VERY familiar with this kind of thing because you run into
it a lot adjusting a Holley carb where there are many MANY adjustments for the
amount of fuel you dump in when you move the throttle plates.
2. The main jet or "Compensation Jet" has the ability to dramatically change
fuel mixture in the mid to high range of engine RPM.
I would very much love to hear Richard Goode go into more detail on how he determines
how much change to make based on engine indications. He obviously has
way more experience than I do. I have seen it done ONCE... but it worked, in
a big way.
I would also like to hear Richard tell me how many clicks on the back of the carb
equates to one jet size....if that is the case at all.
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of Eric Wobschall
Sent: Sun 10/10/2010 4:20 PM
Subject: Re: Yak-List: Cowl design and CHT
Mark, when you say the fuel mixture increase made a big difference, do
you mean the click-stop adjustment on the back of the carburetor?
On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Chris,
>
> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I
> have operated the engine with the spinner off and with the spinner
> on, and for the one cylinder in my engine that has a probe stuck in
> it, the engine ran somewhat cooler with the spinner attached exactly
> as you mention. What the other eight were doing, I have no idea.
>
> That said:
>
> I worked with a gent who put in new higher compression pistons and
> new cylinders (on a M-14 engine) and another person who was having
> very high oil temperature problems (along with cylinder head temps)
> on his M-14PF. In both cases, changing the fuel mixture made a
> DRAMATIC change in temperatures. I mean, taking it from borderline
> RED down into GREEN. The amount of fuel that is dumped into this
> engine makes a dramatic change in temps. Spinners can indeed make
> an impact, but not nearly as much as fuel.
>
> Another interesting tidbit. One Sukhoi (that I had time watching)
> got equipped with a 9 position cylinder head temperature gage (Hubie
> Tolson). I wish he had done an exhaustive study (pun intended) but
> he mainly just wanted to make sure that he knew what the hottest jug
> was. What cylinder ran highest temps changed dramatically from
> running it on the ground, to running it in the air, which is
> logical. As I remember, hottest on the ground was #2. However in
> the air it moved around to #4 or #5 ... I am not sure of that, it
> was awhile ago, but anyway it tends to show that the Russians had a
> good idea what they were doing when they stuck the probe where they
> did.
>
> Lastly, Richard Goode mentioned that the cylinder head temperature
> gages we use are far from being dead nuts calibrated units. I've
> found that to be true as well (using a calibrated IR unit by Raytec
> and also a Thermal IR video unit). What I found from a sampling of
> 5 spare probes was fairly consistent readings between probes, but a
> big difference between gages. I did not even try to calibrate
> mine, but instead just recorded where max temp REALLY was and put a
> mark on the gage. We tend to put faith in what a gage is telling
> us, but that is really far from true. Comparing cylinder head temps
> from one aircraft to another (without first running a calibration
> check on the instruments you are using) ends up being very much like
> comparing apples to oranges.
>
> As an aside, I have only seen one person mess with the jets on these
> engines, and interestingly enough it was done exactly like we did on
> the drag strip. Make a change, go up and fly it, come back.. talk
> about it... make another change, go up and fly it, etc. I doubt if
> there is any real "standard" on how to mess with these things other
> than to have some idea what you are trying to cure and what
> adjustment you should start with, something I wish I knew far more
> about, but don't.
>
> Mark Bitterlich
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
> Sent: Sat 10/9/2010 7:06 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> G'Day Richard,
>
> Years ago I belonged to the Waikerie Gliding Club and used to fly
> the Piper Pawnee 260HP tug.
> As I never competed in any big gliding comps I undertook the role as
> tugmaster.
> Now Waikerie can have temps over 40C on some days as the cyl temps
> would get pretty hot if not careful.
> We found that running a bigger spinner in the summer would
> significantly reduce the cyl head temps as the air was possibly
> directed over the cyl heads more so than a smaller spinner.
>
> I would imagine that the USA has similar climated conditions as we
> have here in Australia.
> When flying the 52 or 18T on these hot summer days, one is always
> aware of the cyl temps.
> The same applies as did the cyl temps on the Pawnee in the summer.
> The Yaks with the big spinners run cooler.
>
> Cheers,
> Chris
>
>
> ----- Original Message -----
> From: Richard Goode <mailto:richard.goode@russianaeros.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 11:53 PM
> Subject: Re: Yak-List: Cowl design and CHT
>
> The main reason that different M14P engines work at different
> temperatures for the same sort of flying is that few owners ever
> bother to change the compensating jets,and running with smaller jets
> [which means more fuel] will greatly reduce CHT.
> The M14P runs very rich most of the time with some of the fuel
> going to cool the cylinders.
> The jets are easy to change [5 minutes with the cowling off];come
> in a range 1.1to 2.1mm.
> In fact it is a good idea to change the jet between summer and
> winter,to avoid over-cooling in winter.
> Richard
>
> Richard Goode Aerobatics
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
> United Kingdom
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com <http://www.russianaeros.com/>
>
>
> ----- Original Message -----
> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 2:50 PM
> Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two
> Sukhois and three Yak 52's running similar power levels. Sukhois
> seem to be able to maintain cool CHT's through any operating
> condition and duration, with hovering at full power on a 95 degree
> day giving green CHT's. The cowl design on the Sukhoi has a leading
> edge that is an airfoil, with an inner cowl shape to speed airflow.
> The Yak 52 uses a cowl design that is a shell with the same external
> shape and no "flying" surface internally to speed airflow. All three
> of the Yak 52's I have flown seem to be limited to climbing Vy at
> max cruise. At any rate, they seem significantly hotter at much less
> extreme conditions. Cowl vents on the Sukhoi are a louver design.
> On the Yak, the cowl venting is a large opening behind the cowl.
> When the Sukhoi Design Bureau added horsepower with the M9R engine,
> they added a larger oil cooler and louvers on the side of the cowl
> that looked more like rear facing opening of a Yak 52. T!
> he!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip
> Holm? Skip has incorporated many of his Reno race speed tricks on
> this M14P powered aircraft. The actual airframe design was penned
> by Sergei Yakovlev. Skip Holm has put a giant spinner on his Bear
> 360. He has also devised an added aerodynamic device placed behind
> the spinner to further reduce drag (unknown effect on CHT). Exhausts
> are flush and aim back into the airflow. The decreased back
> pressure has increased power. The exhaust pressure in the backwards
> direction contribute to airspeed. I am told that six inches of
> protruding exhausts give several knots of speed penalty. Much has
> been said about CO buildup and exhaust design. I hope they have done
> their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing
in
> extreme corners of the operating envelope with a perceived need to
> maintain lower cylinder head temps, should owners develop cowl mods
> to improve cooling? Has anyone attempted to build airfoil shapes
> internal to the existing cowl? Behind the spinner ? I noticed a CHT
> reduction of an average of 20 degrees going from the Russian V530
> two blade prop without spinner to the three blade MT with large
> spinner. Surely there are other mods that could help manage CHT
> further. Am I alone in this thought? My contention is that it would
> be beneficial to be able to climb at any airspeed above the stall at
> full power as long as you wish, ala Sukhoi, without getting into
> yellow CHT's.
>
> Rick Volker
> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List
> ">http://www.matronics======================== <http://www.matronics========================/> <http://www.matronics========================/> <; via the Web
> href="http://forums.matronics.com <http://forums.matronics.com/> <http://forums.matronics.com/> ">http://forums.matronics.com <http://forums.matronics.com/> <http://forums.matronics.com/>
> _p; generous bsp; href="http://www.matronics.com/contribution
> ">http://www.matronics.com/c================
>
>
>
>
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> and is believed to be clean.
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Message 8
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| Subject: | Cowl design and CHT |
I am going to go WAY out on a limb here and ask for comments to this statement:
(Richard? HELP PLEASE!)
My very vague understanding is that the needle click adjustment on the rear of
the carb adjusts the initial set point of the fuel metering tube. Thus it is
basically set for mixture // fuel consumption in the mid range of the engine as
the throttle linkage comes off idle and into initial cruise. This metering
rod comes off the stop as you come above idle, and greatly impacts how much fuel
the engine gets from that point to the point where you get to much higher
power settings.
On the other hand, the compensation or "suction jet" while impacting mixture across
the entire engine operating range to some degree, is mainly meant to adjust
top end power ratings. I.E. Takeoff power and maybe high end cruise settings.
In other words, you would adjust the suction jet at wide open throttle first, and
get that to where the engine is performing right. THEN you would adjust the
initial metering rod adjustment with the "click knob" on the rear of the carb
to control off idle to high mid range power settings.
Please tell me if I am even in the ball park here.
Mark Bitterlich
________________________________
From: owner-yak-list-server@matronics.com on behalf of Bitterlich, Mark G CIV Det
Cherry Point, MALS-14 64E
Sent: Sun 10/10/2010 7:32 PM
Subject: RE: Yak-List: Cowl design and CHT
No, I am talking about the main mixture jet, which Richard Goode refers to as the
"Compensation Jet". Although yes, I have messed with the one you are talking
about.
Being perfectly clear here Eric, I was just a spectator. I profess no special
knowledge on this darn thing other than:
1. I have seen where adjusting the accelerator pump jet will cure hesitation on
throttle advancement versus just plugging the darn thing, which was the initial
cure until smart people figured out you could buy a jet kit and adjust it
accordingly. I am VERY familiar with this kind of thing because you run into
it a lot adjusting a Holley carb where there are many MANY adjustments for the
amount of fuel you dump in when you move the throttle plates.
2. The main jet or "Compensation Jet" has the ability to dramatically change
fuel mixture in the mid to high range of engine RPM.
I would very much love to hear Richard Goode go into more detail on how he determines
how much change to make based on engine indications. He obviously has
way more experience than I do. I have seen it done ONCE... but it worked, in
a big way.
I would also like to hear Richard tell me how many clicks on the back of the carb
equates to one jet size....if that is the case at all.
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of Eric Wobschall
Sent: Sun 10/10/2010 4:20 PM
Subject: Re: Yak-List: Cowl design and CHT
Mark, when you say the fuel mixture increase made a big difference, do
you mean the click-stop adjustment on the back of the carburetor?
On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Chris,
>
> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I
> have operated the engine with the spinner off and with the spinner
> on, and for the one cylinder in my engine that has a probe stuck in
> it, the engine ran somewhat cooler with the spinner attached exactly
> as you mention. What the other eight were doing, I have no idea.
>
> That said:
>
> I worked with a gent who put in new higher compression pistons and
> new cylinders (on a M-14 engine) and another person who was having
> very high oil temperature problems (along with cylinder head temps)
> on his M-14PF. In both cases, changing the fuel mixture made a
> DRAMATIC change in temperatures. I mean, taking it from borderline
> RED down into GREEN. The amount of fuel that is dumped into this
> engine makes a dramatic change in temps. Spinners can indeed make
> an impact, but not nearly as much as fuel.
>
> Another interesting tidbit. One Sukhoi (that I had time watching)
> got equipped with a 9 position cylinder head temperature gage (Hubie
> Tolson). I wish he had done an exhaustive study (pun intended) but
> he mainly just wanted to make sure that he knew what the hottest jug
> was. What cylinder ran highest temps changed dramatically from
> running it on the ground, to running it in the air, which is
> logical. As I remember, hottest on the ground was #2. However in
> the air it moved around to #4 or #5 ... I am not sure of that, it
> was awhile ago, but anyway it tends to show that the Russians had a
> good idea what they were doing when they stuck the probe where they
> did.
>
> Lastly, Richard Goode mentioned that the cylinder head temperature
> gages we use are far from being dead nuts calibrated units. I've
> found that to be true as well (using a calibrated IR unit by Raytec
> and also a Thermal IR video unit). What I found from a sampling of
> 5 spare probes was fairly consistent readings between probes, but a
> big difference between gages. I did not even try to calibrate
> mine, but instead just recorded where max temp REALLY was and put a
> mark on the gage. We tend to put faith in what a gage is telling
> us, but that is really far from true. Comparing cylinder head temps
> from one aircraft to another (without first running a calibration
> check on the instruments you are using) ends up being very much like
> comparing apples to oranges.
>
> As an aside, I have only seen one person mess with the jets on these
> engines, and interestingly enough it was done exactly like we did on
> the drag strip. Make a change, go up and fly it, come back.. talk
> about it... make another change, go up and fly it, etc. I doubt if
> there is any real "standard" on how to mess with these things other
> than to have some idea what you are trying to cure and what
> adjustment you should start with, something I wish I knew far more
> about, but don't.
>
> Mark Bitterlich
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
> Sent: Sat 10/9/2010 7:06 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> G'Day Richard,
>
> Years ago I belonged to the Waikerie Gliding Club and used to fly
> the Piper Pawnee 260HP tug.
> As I never competed in any big gliding comps I undertook the role as
> tugmaster.
> Now Waikerie can have temps over 40C on some days as the cyl temps
> would get pretty hot if not careful.
> We found that running a bigger spinner in the summer would
> significantly reduce the cyl head temps as the air was possibly
> directed over the cyl heads more so than a smaller spinner.
>
> I would imagine that the USA has similar climated conditions as we
> have here in Australia.
> When flying the 52 or 18T on these hot summer days, one is always
> aware of the cyl temps.
> The same applies as did the cyl temps on the Pawnee in the summer.
> The Yaks with the big spinners run cooler.
>
> Cheers,
> Chris
>
>
> ----- Original Message -----
> From: Richard Goode <mailto:richard.goode@russianaeros.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 11:53 PM
> Subject: Re: Yak-List: Cowl design and CHT
>
> The main reason that different M14P engines work at different
> temperatures for the same sort of flying is that few owners ever
> bother to change the compensating jets,and running with smaller jets
> [which means more fuel] will greatly reduce CHT.
> The M14P runs very rich most of the time with some of the fuel
> going to cool the cylinders.
> The jets are easy to change [5 minutes with the cowling off];come
> in a range 1.1to 2.1mm.
> In fact it is a good idea to change the jet between summer and
> winter,to avoid over-cooling in winter.
> Richard
>
> Richard Goode Aerobatics
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
> United Kingdom
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com <http://www.russianaeros.com/>
>
>
> ----- Original Message -----
> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 2:50 PM
> Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two
> Sukhois and three Yak 52's running similar power levels. Sukhois
> seem to be able to maintain cool CHT's through any operating
> condition and duration, with hovering at full power on a 95 degree
> day giving green CHT's. The cowl design on the Sukhoi has a leading
> edge that is an airfoil, with an inner cowl shape to speed airflow.
> The Yak 52 uses a cowl design that is a shell with the same external
> shape and no "flying" surface internally to speed airflow. All three
> of the Yak 52's I have flown seem to be limited to climbing Vy at
> max cruise. At any rate, they seem significantly hotter at much less
> extreme conditions. Cowl vents on the Sukhoi are a louver design.
> On the Yak, the cowl venting is a large opening behind the cowl.
> When the Sukhoi Design Bureau added horsepower with the M9R engine,
> they added a larger oil cooler and louvers on the side of the cowl
> that looked more like rear facing opening of a Yak 52. T!
> he!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip
> Holm? Skip has incorporated many of his Reno race speed tricks on
> this M14P powered aircraft. The actual airframe design was penned
> by Sergei Yakovlev. Skip Holm has put a giant spinner on his Bear
> 360. He has also devised an added aerodynamic device placed behind
> the spinner to further reduce drag (unknown effect on CHT). Exhausts
> are flush and aim back into the airflow. The decreased back
> pressure has increased power. The exhaust pressure in the backwards
> direction contribute to airspeed. I am told that six inches of
> protruding exhausts give several knots of speed penalty. Much has
> been said about CO buildup and exhaust design. I hope they have done
> their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing
in
> extreme corners of the operating envelope with a perceived need to
> maintain lower cylinder head temps, should owners develop cowl mods
> to improve cooling? Has anyone attempted to build airfoil shapes
> internal to the existing cowl? Behind the spinner ? I noticed a CHT
> reduction of an average of 20 degrees going from the Russian V530
> two blade prop without spinner to the three blade MT with large
> spinner. Surely there are other mods that could help manage CHT
> further. Am I alone in this thought? My contention is that it would
> be beneficial to be able to climb at any airspeed above the stall at
> full power as long as you wish, ala Sukhoi, without getting into
> yellow CHT's.
>
> Rick Volker
> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List
> ">http://www.matronics======================== <http://www.matronics========================/> <http://www.matronics========================/> <; via the Web
> href="http://forums.matronics.com <http://forums.matronics.com/> <http://forums.matronics.com/> ">http://forums.matronics.com <http://forums.matronics.com/> <http://forums.matronics.com/>
> _p; generous bsp; href="http://www.matronics.com/contribution
> ">http://www.matronics.com/c================
>
>
>
>
> -----------------------------------------------
> This message has been scanned for viruses and
> dangerous content by the Invictawiz MailScanner
> and is believed to be clean.
> http://www.invictawiz.com <http://www.invictawiz.com/> <http://www.invictawiz.com/> <http://www.invictawiz.com/>
> -----------------------------------------------
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>
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Message 9
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| Subject: | Cowl design and CHT |
Now THIS is good test information.
Thank you Rick. Yes, I very much would like to see that data.
A factoid is that my temperature checks ....which differ from yours ... first
were looked at on a YAK-50 (mine) that has no shutters on the cowl. In other
words, the air has a straight shot into the engine except for the huge spinner.
In that way it is kind of like a Suke with an Iris fully open.
What I do not understand is the test data I got from my friend Hube with the SU-26
using the same JPI engine monitor that apparently you have.
Another thing that you said that grabbed my interest was the position of EGT probes
in the exhaust stacks. This is kind of off-topic, but a lot of experimentation
has been done in this area with smoke systems. People have assumed that
putting the smoke injector higher up in the manifold would result in more burn
and thus more smoke. That did not happen. There is clearly a position just
somewhat above the exhaust exit that is best. This leads me to wonder just
what kind of weird flow is going on in a radials exhaust systems, where a "ring"
is used versus individual stacks going right to a collection point and then
out.
Just put a picture in your mind of an engine firing on every other cylinder and
then look at that exhaust ring and imagine what the gas pressures and flows might
look like and how they behave. In drag racing engines, we work very VERY
hard to equalize back pressure to every cylinder using equal length exhaust tubing
to a central collector. In fact, Tom Johnson on his YAK-50 has a custom
made exhaust system that does exactly that. This ALWAYS increases horsepower,
and equalizes exhaust gas temps to a great extent. So, it makes me wonder...
can we trust exhaust gas readings on an engine using a central "ring" or not?
If not, how much of a spread would there be?
Is it a good idea to run the engine on the ground using a thermal imager and trust
that data? Or just what?
In the end, I gave up. What I decided is that what I thought I knew, really wasn't
trustworthy. I think maybe that the "tune for best performance" idea may
just be the best bet.
With that in mind, I clearly do not know enough about these engines to even have
a valid opinion.
Mark Bitterlich
________________________________
From: owner-yak-list-server@matronics.com on behalf of RICHARD VOLKER
Sent: Sun 10/10/2010 7:18 PM
Subject: Re: Yak-List: Cowl design and CHT
Mark,
I use a JPI engine analyzer on my SU26. On the ground, they are all within 10
degrees of each other- almost equal. In the air, #2 is the hottest, followed
very closely by #1, then #9. The coolest cylinder is #4 (master cylinder),
followed closely by #5. EGT is interesting: The closest spread that I get is
about 70 degrees. 80 degrees for economy cruise. 110 for max cruise. The worst
in flight is 150 degrees diff. at full power. I can run it up at 65% rpm on
the ground and it will take about 20 sec after a long taxi (250 degrees EGT diff
meaning loaded up plugs) to get to a low of 110 degrees diff. That is when
I shut down, assuming plugs are all cleared. I have run two M14P engines on
this JPI monitor and have seen the same profile on each. The EGT diff is normal
for a carbureted engine. The #7 cylinder has very low EGT and is responsible
for most of the differential. Initially on the last engine, I thought this might
be due to some problems with the cylinder and co!
mpression was a little lower than the rest on a high time engine, I replaced it.
The new cylinder had the same low EGT. My new M14P engine again has the same
profile. I am kicking myself for wasting the new cylinder on what is likely
the position of the probe on the #7 exhaust stack, or the shape of the exhaust
stack, or that the fuel happens to sling into this cylinder more( the engine
monitor suggests this) on every engine. All in, you can second guess these things
a bit too much. I have fun keeping all cylinders from getting too cool
on descents. I get to watch the shock cooling alert when I do gyroscopic or severely
yawed maneuvers, as air flow gets rerouted. Flying inverted brings the
coolest cylinders up in temp and the previously hottest cylinders down. The
only reason to use the EGT on this motor would be to diagnose cylinder problems,
or to back up ignition timing. I have been told that Swift fuel has a delayed
burn, requires about a 3 degree advance of timi!
ng with corresponding EGT rise to get 100% power. Leaving tim!
ing stoc
k gives about 97% power but 15 % more range from the same fuel volume. I have
seen an improperly timed M14P crack rings on every cylinder. I will bet this would
have showed on the EGT if the pilot had a similar JPI and knew what to expect.
The JPI probes test accurately.
My old SU29 had the pilot in command panel CHT on #2 cylinder and the passenger
panel CHT on #4. This could be viewed with a little leaning around the head
of the passenger, giving all the info you need. I always thought the poor man's
engine monitor would be an extra Russian CHT on this #4 cylinder- it takes
up very little space and they are plentiful on the used market. If anyone likes,
I will send the JPI monitor profile of the air show I did in 95 degree F
weather. it is a ground start with complete warm up and ground start for the
routine. It carries on for 8 minutes at full manifold pressure and 99% rpm, then
power is reduced with a landing one minute later.
Rick Volker
www.rvairshows,com
On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
wrote:
>
> Chris,
>
> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I have operated
the engine with the spinner off and with the spinner on, and for the one cylinder
in my engine that has a probe stuck in it, the engine ran somewhat cooler
with the spinner attached exactly as you mention. What the other eight were
doing, I have no idea.
>
> That said:
>
> I worked with a gent who put in new higher compression pistons and new cylinders
(on a M-14 engine) and another person who was having very high oil temperature
problems (along with cylinder head temps) on his M-14PF. In both cases,
changing the fuel mixture made a DRAMATIC change in temperatures. I mean, taking
it from borderline RED down into GREEN. The amount of fuel that is dumped
into this engine makes a dramatic change in temps. Spinners can indeed make
an impact, but not nearly as much as fuel.
>
> Another interesting tidbit. One Sukhoi (that I had time watching) got equipped
with a 9 position cylinder head temperature gage (Hubie Tolson). I wish he
had done an exhaustive study (pun intended) but he mainly just wanted to make
sure that he knew what the hottest jug was. What cylinder ran highest temps
changed dramatically from running it on the ground, to running it in the air,
which is logical. As I remember, hottest on the ground was #2. However in the
air it moved around to #4 or #5 ... I am not sure of that, it was awhile ago,
but anyway it tends to show that the Russians had a good idea what they were
doing when they stuck the probe where they did.
>
> Lastly, Richard Goode mentioned that the cylinder head temperature gages we use
are far from being dead nuts calibrated units. I've found that to be true
as well (using a calibrated IR unit by Raytec and also a Thermal IR video unit).
What I found from a sampling of 5 spare probes was fairly consistent readings
between probes, but a big difference between gages. I did not even try
to calibrate mine, but instead just recorded where max temp REALLY was and put
a mark on the gage. We tend to put faith in what a gage is telling us, but
that is really far from true. Comparing cylinder head temps from one aircraft
to another (without first running a calibration check on the instruments you
are using) ends up being very much like comparing apples to oranges.
>
> As an aside, I have only seen one person mess with the jets on these engines,
and interestingly enough it was done exactly like we did on the drag strip.
Make a change, go up and fly it, come back.. talk about it... make another change,
go up and fly it, etc. I doubt if there is any real "standard" on how to
mess with these things other than to have some idea what you are trying to cure
and what adjustment you should start with, something I wish I knew far more
about, but don't.
>
> Mark Bitterlich
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
> Sent: Sat 10/9/2010 7:06 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> G'Day Richard,
>
> Years ago I belonged to the Waikerie Gliding Club and used to fly the Piper Pawnee
260HP tug.
> As I never competed in any big gliding comps I undertook the role as tugmaster.
> Now Waikerie can have temps over 40C on some days as the cyl temps would get
pretty hot if not careful.
> We found that running a bigger spinner in the summer would significantly reduce
the cyl head temps as the air was possibly directed over the cyl heads more
so than a smaller spinner.
>
> I would imagine that the USA has similar climated conditions as we have here
in Australia.
> When flying the 52 or 18T on these hot summer days, one is always aware of the
cyl temps.
> The same applies as did the cyl temps on the Pawnee in the summer.
> The Yaks with the big spinners run cooler.
>
> Cheers,
> Chris
>
>
> ----- Original Message -----
> From: Richard Goode <mailto:richard.goode@russianaeros.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 11:53 PM
> Subject: Re: Yak-List: Cowl design and CHT
>
> The main reason that different M14P engines work at different temperatures
for the same sort of flying is that few owners ever bother to change the compensating
jets,and running with smaller jets [which means more fuel] will greatly
reduce CHT.
> The M14P runs very rich most of the time with some of the fuel going to
cool the cylinders.
> The jets are easy to change [5 minutes with the cowling off];come in a
range 1.1to 2.1mm.
> In fact it is a good idea to change the jet between summer and winter,to
avoid over-cooling in winter.
> Richard
>
> Richard Goode Aerobatics
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
> United Kingdom
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com <http://www.russianaeros.com/>
>
>
> ----- Original Message -----
> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
> To: yak-list@matronics.com
> Sent: Saturday, October 09, 2010 2:50 PM
> Subject: Yak-List: Cowl design and CHT
>
>
>
> I have noticed large differences in the CHT temps of two Sukhois
and three Yak 52's running similar power levels. Sukhois seem to be able
to maintain cool CHT's through any operating condition and duration, with hovering
at full power on a 95 degree day giving green CHT's. The cowl design on the
Sukhoi has a leading edge that is an airfoil, with an inner cowl shape to speed
airflow. The Yak 52 uses a cowl design that is a shell with the same external
shape and no "flying" surface internally to speed airflow. All three of the
Yak 52's I have flown seem to be limited to climbing Vy at max cruise. At any
rate, they seem significantly hotter at much less extreme conditions. Cowl
vents on the Sukhoi are a louver design. On the Yak, the cowl venting is a large
opening behind the cowl. When the Sukhoi Design Bureau added horsepower with
the M9R engine, they added a larger oil cooler and louvers on the side of
the cowl that looked more like rear facing opening of a Yak 52. !
T!
> he!
> se Russians must talk to each other!
>
> Has anyone seen the BEAR 360 that has been marketed by Skip
Holm? Skip has incorporated many of his Reno race speed tricks on this M14P
powered aircraft. The actual airframe design was penned by Sergei Yakovlev. Skip
Holm has put a giant spinner on his Bear 360. He has also devised an added
aerodynamic device placed behind the spinner to further reduce drag (unknown
effect on CHT). Exhausts are flush and aim back into the airflow. The decreased
back pressure has increased power. The exhaust pressure in the backwards direction
contribute to airspeed. I am told that six inches of protruding exhausts
give several knots of speed penalty. Much has been said about CO buildup
and exhaust design. I hope they have done their homework in that respect.
>
> My question is this: Since more Yak 52 owners are playing
in extreme corners of the operating envelope with a perceived need to maintain
lower cylinder head temps, should owners develop cowl mods to improve cooling?
Has anyone attempted to build airfoil shapes internal to the existing cowl?
Behind the spinner ? I noticed a CHT reduction of an average of 20 degrees going
from the Russian V530 two blade prop without spinner to the three blade MT
with large spinner. Surely there are other mods that could help manage CHT
further. Am I alone in this thought? My contention is that it would be beneficial
to be able to climb at any airspeed above the stall at full power as long
as you wish, ala Sukhoi, without getting into yellow CHT's.
>
> Rick Volker
> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics======================== <http://www.matronics========================/> <; via the Web href="http://forums.matronics.com <http://forums.matronics.com/> ">http://forums.matronics.com <http://forums.matronics.com/>
> _p; generous bsp; href="http://www.matronics.com/contribution">http://www.matronics.com/c================
>
>
>
>
> -----------------------------------------------
> This message has been scanned for viruses and
> dangerous content by the Invictawiz MailScanner
> and is believed to be clean.
> http://www.invictawiz.com <http://www.invictawiz.com/> <http://www.invictawiz.com/>
> -----------------------------------------------
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>
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>
> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
> href="http://forums.matronics.com <http://forums.matronics.com/> ">http://forums.matronics.com <http://forums.matronics.com/>
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Message 10
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| Subject: | Re: Cowl design and CHT |
Mark:
I had what I considered to be somewhat high CHT on a VERY LOW TIME
first run factory engine. This was with factory settings which I was
loathe to touch. I'm in Western NY state, so you'd think average
settings would cover me. I have checked and tightened various things,
including cylinder and supercharger case gland nuts. The temps seem to
have crept down. Maybe some of it is break-in, although Jill G. would
say break-in is done on a test stand before it sees an airplane. Maybe
I've gotten better at managing climb angle, etc.
Rick Volker has been around this plane and felt there was an issue
compared with the Sukhois he owned. He also feels spinner and cowl
play a big part. as you've read.
I did ring up Vladamir Yastremski (sp?), and he said my temps were
well within acceptable limits, and to worry more about low temps.
Dennis S. has said about the same thing in the past. Rick suggested
test where I climb-out at Vy to 5000 ft. I tried that, and I kept it
under 210 C, and then leveled off at max cruise, after which time it
stayed in the high green. So that wasn't bad. Now keep in mind this
was at 63 degrees ambient at the departure airport (KBQR 752').
About all of these jets: Richard Goode says they all need adjusting,
and I think it was Sergei Prolegiev who suggested that I get it out of
my head that it left the factory perfectly adjusted. I do have a
slight hesitation when I feed power back in on final, but it's not
scary. I have all of the different jets, if only I knew what I was
doing. I was hoping one or two clockwise clicks on the cruise mixture
adjustment would enrichen the mixture enough to make my plane and I
happy. I do have great fuel economy, so maybe I'm lean.
Here's my gage and the Yak-UK translated DOSAAF manual I usually go
by. Remarks, anyone? -Eric
On Oct 10, 2010, at 7:32 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> No, I am talking about the main mixture jet, which Richard Goode
> refers to as the "Compensation Jet". Although yes, I have messed
> with the one you are talking about.
>
> Being perfectly clear here Eric, I was just a spectator. I profess
> no special knowledge on this darn thing other than:
>
> 1. I have seen where adjusting the accelerator pump jet will cure
> hesitation on throttle advancement versus just plugging the darn
> thing, which was the initial cure until smart people figured out you
> could buy a jet kit and adjust it accordingly. I am VERY familiar
> with this kind of thing because you run into it a lot adjusting a
> Holley carb where there are many MANY adjustments for the amount of
> fuel you dump in when you move the throttle plates.
>
> 2. The main jet or "Compensation Jet" has the ability to
> dramatically change fuel mixture in the mid to high range of engine
> RPM.
>
> I would very much love to hear Richard Goode go into more detail on
> how he determines how much change to make based on engine
> indications. He obviously has way more experience than I do. I
> have seen it done ONCE... but it worked, in a big way.
>
> I would also like to hear Richard tell me how many clicks on the
> back of the carb equates to one jet size....if that is the case at
> all.
>
> Mark
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Eric Wobschall
> Sent: Sun 10/10/2010 4:20 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> >
>
> Mark, when you say the fuel mixture increase made a big difference, do
> you mean the click-stop adjustment on the back of the carburetor?
>
>
> On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point,
> MALS-14 64E wrote:
>
>> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> Chris,
>>
>> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I
>> have operated the engine with the spinner off and with the spinner
>> on, and for the one cylinder in my engine that has a probe stuck in
>> it, the engine ran somewhat cooler with the spinner attached exactly
>> as you mention. What the other eight were doing, I have no idea.
>>
>> That said:
>>
>> I worked with a gent who put in new higher compression pistons and
>> new cylinders (on a M-14 engine) and another person who was having
>> very high oil temperature problems (along with cylinder head temps)
>> on his M-14PF. In both cases, changing the fuel mixture made a
>> DRAMATIC change in temperatures. I mean, taking it from borderline
>> RED down into GREEN. The amount of fuel that is dumped into this
>> engine makes a dramatic change in temps. Spinners can indeed make
>> an impact, but not nearly as much as fuel.
>>
>> Another interesting tidbit. One Sukhoi (that I had time watching)
>> got equipped with a 9 position cylinder head temperature gage (Hubie
>> Tolson). I wish he had done an exhaustive study (pun intended) but
>> he mainly just wanted to make sure that he knew what the hottest jug
>> was. What cylinder ran highest temps changed dramatically from
>> running it on the ground, to running it in the air, which is
>> logical. As I remember, hottest on the ground was #2. However in
>> the air it moved around to #4 or #5 ... I am not sure of that, it
>> was awhile ago, but anyway it tends to show that the Russians had a
>> good idea what they were doing when they stuck the probe where they
>> did.
>>
>> Lastly, Richard Goode mentioned that the cylinder head temperature
>> gages we use are far from being dead nuts calibrated units. I've
>> found that to be true as well (using a calibrated IR unit by Raytec
>> and also a Thermal IR video unit). What I found from a sampling of
>> 5 spare probes was fairly consistent readings between probes, but a
>> big difference between gages. I did not even try to calibrate
>> mine, but instead just recorded where max temp REALLY was and put a
>> mark on the gage. We tend to put faith in what a gage is telling
>> us, but that is really far from true. Comparing cylinder head temps
>> from one aircraft to another (without first running a calibration
>> check on the instruments you are using) ends up being very much like
>> comparing apples to oranges.
>>
>> As an aside, I have only seen one person mess with the jets on these
>> engines, and interestingly enough it was done exactly like we did on
>> the drag strip. Make a change, go up and fly it, come back.. talk
>> about it... make another change, go up and fly it, etc. I doubt if
>> there is any real "standard" on how to mess with these things other
>> than to have some idea what you are trying to cure and what
>> adjustment you should start with, something I wish I knew far more
>> about, but don't.
>>
>> Mark Bitterlich
>>
>>
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
>> Sent: Sat 10/9/2010 7:06 PM
>> To: yak-list@matronics.com
>> Subject: Re: Yak-List: Cowl design and CHT
>>
>>
>> G'Day Richard,
>>
>> Years ago I belonged to the Waikerie Gliding Club and used to fly
>> the Piper Pawnee 260HP tug.
>> As I never competed in any big gliding comps I undertook the role as
>> tugmaster.
>> Now Waikerie can have temps over 40C on some days as the cyl temps
>> would get pretty hot if not careful.
>> We found that running a bigger spinner in the summer would
>> significantly reduce the cyl head temps as the air was possibly
>> directed over the cyl heads more so than a smaller spinner.
>>
>> I would imagine that the USA has similar climated conditions as we
>> have here in Australia.
>> When flying the 52 or 18T on these hot summer days, one is always
>> aware of the cyl temps.
>> The same applies as did the cyl temps on the Pawnee in the summer.
>> The Yaks with the big spinners run cooler.
>>
>> Cheers,
>> Chris
>>
>>
>>
>>
>> ----- Original Message -----
>> From: Richard Goode <mailto:richard.goode@russianaeros.com>
>> To: yak-list@matronics.com
>> Sent: Saturday, October 09, 2010 11:53 PM
>> Subject: Re: Yak-List: Cowl design and CHT
>>
>> The main reason that different M14P engines work at different
>> temperatures for the same sort of flying is that few owners ever
>> bother to change the compensating jets,and running with smaller jets
>> [which means more fuel] will greatly reduce CHT.
>> The M14P runs very rich most of the time with some of the fuel
>> going to cool the cylinders.
>> The jets are easy to change [5 minutes with the cowling
>> off];come
>> in a range 1.1to 2.1mm.
>> In fact it is a good idea to change the jet between summer and
>> winter,to avoid over-cooling in winter.
>> Richard
>>
>> Richard Goode Aerobatics
>> Rhodds Farm
>> Lyonshall
>> Hereford
>> HR5 3LW
>> United Kingdom
>>
>> Tel: +44 (0) 1544 340120
>> Fax: +44 (0) 1544 340129
>> www.russianaeros.com <http://www.russianaeros.com/>
>>
>>
>> ----- Original Message -----
>> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
>> To: yak-list@matronics.com
>> Sent: Saturday, October 09, 2010 2:50 PM
>> Subject: Yak-List: Cowl design and CHT
>>
>> >
>>
>>
>> I have noticed large differences in the CHT temps
>> of two
>> Sukhois and three Yak 52's running similar power levels. Sukhois
>> seem to be able to maintain cool CHT's through any operating
>> condition and duration, with hovering at full power on a 95 degree
>> day giving green CHT's. The cowl design on the Sukhoi has a leading
>> edge that is an airfoil, with an inner cowl shape to speed airflow.
>> The Yak 52 uses a cowl design that is a shell with the same external
>> shape and no "flying" surface internally to speed airflow. All three
>> of the Yak 52's I have flown seem to be limited to climbing Vy at
>> max cruise. At any rate, they seem significantly hotter at much less
>> extreme conditions. Cowl vents on the Sukhoi are a louver design.
>> On the Yak, the cowl venting is a large opening behind the cowl.
>> When the Sukhoi Design Bureau added horsepower with the M9R engine,
>> they added a larger oil cooler and louvers on the side of the cowl
>> that looked more like rear facing opening of a Yak 52. T!
>> he!
>> se Russians must talk to each other!
>>
>> Has anyone seen the BEAR 360 that has been
>> marketed by Skip
>> Holm? Skip has incorporated many of his Reno race speed tricks on
>> this M14P powered aircraft. The actual airframe design was penned
>> by Sergei Yakovlev. Skip Holm has put a giant spinner on his Bear
>> 360. He has also devised an added aerodynamic device placed behind
>> the spinner to further reduce drag (unknown effect on CHT). Exhausts
>> are flush and aim back into the airflow. The decreased back
>> pressure has increased power. The exhaust pressure in the backwards
>> direction contribute to airspeed. I am told that six inches of
>> protruding exhausts give several knots of speed penalty. Much has
>> been said about CO buildup and exhaust design. I hope they have done
>> their homework in that respect.
>>
>> My question is this: Since more Yak 52 owners are
>> playing in
>> extreme corners of the operating envelope with a perceived need to
>> maintain lower cylinder head temps, should owners develop cowl mods
>> to improve cooling? Has anyone attempted to build airfoil shapes
>> internal to the existing cowl? Behind the spinner ? I noticed a CHT
>> reduction of an average of 20 degrees going from the Russian V530
>> two blade prop without spinner to the three blade MT with large
>> spinner. Surely there are other mods that could help manage CHT
>> further. Am I alone in this thought? My contention is that it would
>> be beneficial to be able to climb at any airspeed above the stall at
>> full power as long as you wish, ala Sukhoi, without getting into
>> yellow CHT's.
>>
>> Rick Volker
>> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List
>> ">http://www.matronics======================== <http://www.matronics========================/
>> > <; via the Web
>> href="http://forums.matronics.com <http://forums.matronics.com/> ">http://forums.matronics.com
>> <http://forums.matronics.com/>
>> _p; generous bsp; href="http://www.matronics.com/contribution
>> ">http://www.matronics.com/c================
>>
>>
>>
>>
>> -----------------------------------------------
>> This message has been scanned for viruses and
>> dangerous content by the Invictawiz MailScanner
>> and is believed to be clean.
>> http://www.invictawiz.com <http://www.invictawiz.com/
>> > <http://www.invictawiz.com/>
>> -----------------------------------------------
>>
>>
>>
>>
>> href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
>> href="http://forums.matronics.com <http://forums.matronics.com/
>> > ">http://forums.matronics.com <http://forums.matronics.com/>
>> href="http://www.matronics.com/contribution">http://www.matronics.com/c
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Eric D. Wobschall
Buffalo Skyline
Buffalo-Lancaster Airport (KBQR):
4343 Walden Avenue
Lancaster, NY 14086
Office:
2120 Maple Road
Williamsville, NY 14221-1922
716.208.5460
Message 11
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| Subject: | Re: Cowl design and CHT |
Mark:
I had what I considered to be somewhat high CHT on a VERY LOW TIME
first run factory engine. This was with factory settings which I was
loathe to touch. I'm in Western NY state, so you'd think average
settings would cover me. I have checked and tightened various things,
including cylinder and supercharger case gland nuts. The temps seem to
have crept down. Maybe some of it is break-in, although Jill G. would
say break-in is done on a test stand before it sees an airplane. Maybe
I've gotten better at managing climb angle, etc.
Rick Volker has been around this plane and felt there was an issue
compared with the Sukhois he owned. He also feels spinner and cowl
play a big part. as you've read.
I did ring up Vladamir Yastremski (sp?), and he said my temps were
well within acceptable limits, and to worry more about low temps.
Dennis S. has said about the same thing in the past. Rick suggested
test where I climb-out at Vy to 5000 ft. I tried that, and I kept it
under 210 C, and then leveled off at max cruise, after which time it
stayed in the high green. So that wasn't bad. Now keep in mind this
was at 63 degrees ambient at the departure airport (KBQR 752').
About all of these jets: Richard Goode says they all need adjusting,
and I think it was Sergei Prolegiev who suggested that I get it out of
my head that it left the factory perfectly adjusted. I do have a
slight hesitation when I feed power back in on final, but it's not
scary. I have all of the different jets, if only I knew what I was
doing. I was hoping one or two clockwise clicks on the cruise mixture
adjustment would enrichen the mixture enough to make my plane and I
happy. I do have great fuel economy, so maybe I'm lean.
Here's my gage and the Yak-UK translated DOSAAF manual I usually go
by. Remarks, anyone? -Eric
On Oct 10, 2010, at 7:32 PM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> No, I am talking about the main mixture jet, which Richard Goode
> refers to as the "Compensation Jet". Although yes, I have messed
> with the one you are talking about.
>
> Being perfectly clear here Eric, I was just a spectator. I profess
> no special knowledge on this darn thing other than:
>
> 1. I have seen where adjusting the accelerator pump jet will cure
> hesitation on throttle advancement versus just plugging the darn
> thing, which was the initial cure until smart people figured out you
> could buy a jet kit and adjust it accordingly. I am VERY familiar
> with this kind of thing because you run into it a lot adjusting a
> Holley carb where there are many MANY adjustments for the amount of
> fuel you dump in when you move the throttle plates.
>
> 2. The main jet or "Compensation Jet" has the ability to
> dramatically change fuel mixture in the mid to high range of engine
> RPM.
>
> I would very much love to hear Richard Goode go into more detail on
> how he determines how much change to make based on engine
> indications. He obviously has way more experience than I do. I
> have seen it done ONCE... but it worked, in a big way.
>
> I would also like to hear Richard tell me how many clicks on the
> back of the carb equates to one jet size....if that is the case at
> all.
>
> Mark
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Eric Wobschall
> Sent: Sun 10/10/2010 4:20 PM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Cowl design and CHT
>
>
> >
>
> Mark, when you say the fuel mixture increase made a big difference, do
> you mean the click-stop adjustment on the back of the carburetor?
>
>
> On Oct 10, 2010, at 3:05 PM, Bitterlich, Mark G CIV Det Cherry Point,
> MALS-14 64E wrote:
>
>> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> Chris,
>>
>> I run a YAK-18T spinner on my YAK-50. It is one huge spinner. I
>> have operated the engine with the spinner off and with the spinner
>> on, and for the one cylinder in my engine that has a probe stuck in
>> it, the engine ran somewhat cooler with the spinner attached exactly
>> as you mention. What the other eight were doing, I have no idea.
>>
>> That said:
>>
>> I worked with a gent who put in new higher compression pistons and
>> new cylinders (on a M-14 engine) and another person who was having
>> very high oil temperature problems (along with cylinder head temps)
>> on his M-14PF. In both cases, changing the fuel mixture made a
>> DRAMATIC change in temperatures. I mean, taking it from borderline
>> RED down into GREEN. The amount of fuel that is dumped into this
>> engine makes a dramatic change in temps. Spinners can indeed make
>> an impact, but not nearly as much as fuel.
>>
>> Another interesting tidbit. One Sukhoi (that I had time watching)
>> got equipped with a 9 position cylinder head temperature gage (Hubie
>> Tolson). I wish he had done an exhaustive study (pun intended) but
>> he mainly just wanted to make sure that he knew what the hottest jug
>> was. What cylinder ran highest temps changed dramatically from
>> running it on the ground, to running it in the air, which is
>> logical. As I remember, hottest on the ground was #2. However in
>> the air it moved around to #4 or #5 ... I am not sure of that, it
>> was awhile ago, but anyway it tends to show that the Russians had a
>> good idea what they were doing when they stuck the probe where they
>> did.
>>
>> Lastly, Richard Goode mentioned that the cylinder head temperature
>> gages we use are far from being dead nuts calibrated units. I've
>> found that to be true as well (using a calibrated IR unit by Raytec
>> and also a Thermal IR video unit). What I found from a sampling of
>> 5 spare probes was fairly consistent readings between probes, but a
>> big difference between gages. I did not even try to calibrate
>> mine, but instead just recorded where max temp REALLY was and put a
>> mark on the gage. We tend to put faith in what a gage is telling
>> us, but that is really far from true. Comparing cylinder head temps
>> from one aircraft to another (without first running a calibration
>> check on the instruments you are using) ends up being very much like
>> comparing apples to oranges.
>>
>> As an aside, I have only seen one person mess with the jets on these
>> engines, and interestingly enough it was done exactly like we did on
>> the drag strip. Make a change, go up and fly it, come back.. talk
>> about it... make another change, go up and fly it, etc. I doubt if
>> there is any real "standard" on how to mess with these things other
>> than to have some idea what you are trying to cure and what
>> adjustment you should start with, something I wish I knew far more
>> about, but don't.
>>
>> Mark Bitterlich
>>
>>
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of Chris Wise
>> Sent: Sat 10/9/2010 7:06 PM
>> To: yak-list@matronics.com
>> Subject: Re: Yak-List: Cowl design and CHT
>>
>>
>> G'Day Richard,
>>
>> Years ago I belonged to the Waikerie Gliding Club and used to fly
>> the Piper Pawnee 260HP tug.
>> As I never competed in any big gliding comps I undertook the role as
>> tugmaster.
>> Now Waikerie can have temps over 40C on some days as the cyl temps
>> would get pretty hot if not careful.
>> We found that running a bigger spinner in the summer would
>> significantly reduce the cyl head temps as the air was possibly
>> directed over the cyl heads more so than a smaller spinner.
>>
>> I would imagine that the USA has similar climated conditions as we
>> have here in Australia.
>> When flying the 52 or 18T on these hot summer days, one is always
>> aware of the cyl temps.
>> The same applies as did the cyl temps on the Pawnee in the summer.
>> The Yaks with the big spinners run cooler.
>>
>> Cheers,
>> Chris
>>
>>
>>
>>
>> ----- Original Message -----
>> From: Richard Goode <mailto:richard.goode@russianaeros.com>
>> To: yak-list@matronics.com
>> Sent: Saturday, October 09, 2010 11:53 PM
>> Subject: Re: Yak-List: Cowl design and CHT
>>
>> The main reason that different M14P engines work at different
>> temperatures for the same sort of flying is that few owners ever
>> bother to change the compensating jets,and running with smaller jets
>> [which means more fuel] will greatly reduce CHT.
>> The M14P runs very rich most of the time with some of the fuel
>> going to cool the cylinders.
>> The jets are easy to change [5 minutes with the cowling
>> off];come
>> in a range 1.1to 2.1mm.
>> In fact it is a good idea to change the jet between summer and
>> winter,to avoid over-cooling in winter.
>> Richard
>>
>> Richard Goode Aerobatics
>> Rhodds Farm
>> Lyonshall
>> Hereford
>> HR5 3LW
>> United Kingdom
>>
>> Tel: +44 (0) 1544 340120
>> Fax: +44 (0) 1544 340129
>> www.russianaeros.com <http://www.russianaeros.com/>
>>
>>
>> ----- Original Message -----
>> From: RICHARD VOLKER <mailto:rick@rvairshows.com>
>> To: yak-list@matronics.com
>> Sent: Saturday, October 09, 2010 2:50 PM
>> Subject: Yak-List: Cowl design and CHT
>>
>> >
>>
>>
>> I have noticed large differences in the CHT temps
>> of two
>> Sukhois and three Yak 52's running similar power levels. Sukhois
>> seem to be able to maintain cool CHT's through any operating
>> condition and duration, with hovering at full power on a 95 degree
>> day giving green CHT's. The cowl design on the Sukhoi has a leading
>> edge that is an airfoil, with an inner cowl shape to speed airflow.
>> The Yak 52 uses a cowl design that is a shell with the same external
>> shape and no "flying" surface internally to speed airflow. All three
>> of the Yak 52's I have flown seem to be limited to climbing Vy at
>> max cruise. At any rate, they seem significantly hotter at much less
>> extreme conditions. Cowl vents on the Sukhoi are a louver design.
>> On the Yak, the cowl venting is a large opening behind the cowl.
>> When the Sukhoi Design Bureau added horsepower with the M9R engine,
>> they added a larger oil cooler and louvers on the side of the cowl
>> that looked more like rear facing opening of a Yak 52. T!
>> he!
>> se Russians must talk to each other!
>>
>> Has anyone seen the BEAR 360 that has been
>> marketed by Skip
>> Holm? Skip has incorporated many of his Reno race speed tricks on
>> this M14P powered aircraft. The actual airframe design was penned
>> by Sergei Yakovlev. Skip Holm has put a giant spinner on his Bear
>> 360. He has also devised an added aerodynamic device placed behind
>> the spinner to further reduce drag (unknown effect on CHT). Exhausts
>> are flush and aim back into the airflow. The decreased back
>> pressure has increased power. The exhaust pressure in the backwards
>> direction contribute to airspeed. I am told that six inches of
>> protruding exhausts give several knots of speed penalty. Much has
>> been said about CO buildup and exhaust design. I hope they have done
>> their homework in that respect.
>>
>> My question is this: Since more Yak 52 owners are
>> playing in
>> extreme corners of the operating envelope with a perceived need to
>> maintain lower cylinder head temps, should owners develop cowl mods
>> to improve cooling? Has anyone attempted to build airfoil shapes
>> internal to the existing cowl? Behind the spinner ? I noticed a CHT
>> reduction of an average of 20 degrees going from the Russian V530
>> two blade prop without spinner to the three blade MT with large
>> spinner. Surely there are other mods that could help manage CHT
>> further. Am I alone in this thought? My contention is that it would
>> be beneficial to be able to climb at any airspeed above the stall at
>> full power as long as you wish, ala Sukhoi, without getting into
>> yellow CHT's.
>>
>> Rick Volker
>> p; Navigator Photoshare, and href="http://www.matronics.com/Navigator?Yak-List
>> ">http://www.matronics======================== <http://www.matronics========================/
>> > <; via the Web
>> href="http://forums.matronics.com <http://forums.matronics.com/> ">http://forums.matronics.com
>> <http://forums.matronics.com/>
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Eric D. Wobschall
Buffalo Skyline
Buffalo-Lancaster Airport (KBQR):
4343 Walden Avenue
Lancaster, NY 14086
Office:
2120 Maple Road
Williamsville, NY 14221-1922
716.208.5460
Message 12
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| Subject: | Re: Cowl design and CHT |
Hello,
another thing to keep in mind : In a radial engine you have different stroke for
each piston, in fact several millimeters difference in the M14. So you have
different compression ratios as well. This will have some effect on power and
temperature for each cylinder. But then, this should concern cylinders with some
of the longest strokes to run hotter than the rest. Maybe this fact gets clouded
by some other effects still unreflected.
Vic
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=315298#315298
Message 13
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I'm told that ELK-12180 batteries fit a Yak 52, but I can't find any locally.
What can anyone recommend that can be had at Walmart, Advance Auto, Auto Zone,
etc?
Message 14
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Try The Battery Source. They can match up just about any battery you need.
Doc
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Thomas Smith
Sent: Sunday, October 10, 2010 9:55 PM
Subject: Yak-List: Batteries
I'm told that ELK-12180 batteries fit a Yak 52, but I can't find any
locally. What can anyone recommend that can be had at Walmart, Advance
Auto, Auto Zone, etc?
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