Page 1 of 1

Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by rebel
Has anyone modified the cowling inlets for the Rebel speed cowl? The #1
cylinder (Lycoming) is about 3" back from the front of the cowling. It looks as
though the air wants to hit the baffle and bounce right back out. Someone has
published info about the inlet air wanting to come back out near the prop hub
and now I can see why. I plan to modify the inlet so that there is a smoother
transition for the inlet air. If anyone has done this already I would like to
see their work. My plan is to fiberglass a ramp up to within 1" of the cylinder
and then rivet a piece of silicone baffle seal onto the ramp. The silicone
baffle seal will rest right up against the cylinder fins and will curl upwards.
I never liked the "comb" look of the aluminum baffle after it has sat on the
fins and cut into the baffle.
If you look at some of the RV's you will see how they use a baffle in the front
center of the engine to contain the air and force it out through the cyl fins.
I plan to add that on my Rebel also. Any comments will be appreciated.
Good luck, you'll need it and more
Rick D
Rebel 404R (trying to finish engine baffling)





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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Wayne G. O'Shea
This is the reason that our (read Canadian) Homebuilts will not (at least
are not supposed to) pass a final inspection in Canada unless the aluminum
baffles against the cylinder fins are (HTRTV)siliconed in place. Just enough
of an RTV bead between the two to bond and keep the aluminum baffle from
chewing up itself or the cooling fins and not so much that it ouzes in and
fills the fins.

Wayne

----- Original Message -----
From: <rebel@dcsol.com>
To: <murphy-rebel@dcsol.com>
Sent: Friday, January 10, 2003 12:43 PM
Subject: Rebel cowl mods

I never liked the "comb" look of the aluminum baffle after it has sat on
the
fins and cut into the baffle.




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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Bill Delcambre
I don't have much to say about the details of the Rebel cowl, but will
comment on one item that you wrote. About 6 years ago, I rebuilt the
baffling on my plane. I bought a tube of red silicone sealant, and ran a
small (3/16") bead to act as a vibration insulator, where ever a piece of
baffle touched another baffle, as well as along the line where the aluminum
rested against the cylinder fins. The bead is not bonding anything, mind
you. I let this small bead cure completely, before any two parts touched.
This has worked so well, I'm gonna do it on my Moose. Even the silicone
baffle material gets the comb look, after a while, but this cured sealant
still looks like the day it was installed. It's easy, inexpensive and it
worked for me!

Bill Delcambre

Has anyone modified the cowling inlets for the Rebel speed cowl? The #1
cylinder (Lycoming) is about 3" back from the front of the cowling. It
looks as
though the air wants to hit the baffle and bounce right back out. Someone
has
published info about the inlet air wanting to come back out near the prop
hub
and now I can see why. I plan to modify the inlet so that there is a
smoother
transition for the inlet air. If anyone has done this already I would like
to
see their work. My plan is to fiberglass a ramp up to within 1" of the
cylinder
and then rivet a piece of silicone baffle seal onto the ramp. The silicone
baffle seal will rest right up against the cylinder fins and will curl
upwards.
I never liked the "comb" look of the aluminum baffle after it has sat on
the
fins and cut into the baffle.
If you look at some of the RV's you will see how they use a baffle in the
front
center of the engine to contain the air and force it out through the cyl
fins.
I plan to add that on my Rebel also. Any comments will be appreciated.
Good luck, you'll need it and more
Rick D
Rebel 404R (trying to finish engine baffling)




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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Walter Klatt
If you search back in the archives, you will find that
I and a few others have had a lot of cooling problems
with the 0320 and the fibreglass cowl.

I have a baffle in front that ramps the air up from the
inlet to more than half way up the cylinder. Also, I
have cut back the inlet lips and smoothed them up to
the cowl top.

If I were doing my cowl over, I would also make the
inlets bigger overall, as I know a couple of local guys
here have done to solve the cooling problem. This is on
floats. On wheels it is OK, but floats slows it down
just enough, and of course, you have to climb longer at
full power to get up to altitude, so on climb it just
heats up more than you want.

I have done everything possible with the outlets, as
has been described on this list, and it is still just
barely acceptable. I just think there isn't enough
getting in the front. When I look at a 172 or 180, they
have about 3 times as much inlet area as this cowl.

I might mention that this was with the Warp Drive prop.
Now with my Sensenich, it is definitely running about
50 degrees F cooler, but it is also winter now.

Never had a problem with oil cooling, just CHT's. In
fact right now, I have 2/3 of my cooler taped off to
make it run warmer.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
rebel@dcsol.com
Sent: Friday, January 10, 2003 9:43 AM
To: murphy-rebel@dcsol.com
Subject: Rebel cowl mods


Has anyone modified the cowling inlets for
the Rebel speed cowl? The #1
cylinder (Lycoming) is about 3" back from
the front of the cowling. It looks as
though the air wants to hit the baffle and
bounce right back out. Someone has
published info about the inlet air wanting
to come back out near the prop hub
and now I can see why. I plan to modify the
inlet so that there is a smoother
transition for the inlet air. If anyone has
done this already I would like to
see their work. My plan is to fiberglass a
ramp up to within 1" of the cylinder
and then rivet a piece of silicone baffle
seal onto the ramp. The silicone
baffle seal will rest right up against the
cylinder fins and will curl upwards.
I never liked the "comb" look of the
aluminum baffle after it has sat on the
fins and cut into the baffle.
If you look at some of the RV's you will see
how they use a baffle in the front
center of the engine to contain the air and
force it out through the cyl fins.
I plan to add that on my Rebel also. Any
comments will be appreciated.
Good luck, you'll need it and more
Rick D
Rebel 404R (trying to finish engine baffling)




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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by klehman
Tony Bingelis talks a little about overheating of the right front
cylinder on pg.95 of 'The Sportplane builder'. He mentions a Bellanca
using an extended lip on the inlet to catch the air that was being
sucked out. Alternatively he also mentions identing the lower lip of the
opening on a Trojan to accomplish the same thing with turbulence.
Not much more info there but I've also heard it claimed that this effect
diminishes greatly by 3 blade cord widths behind the prop. I believe
moving the prop forward with a spacer generally reduces drag and
improves airflow into the cowl.

Another thing is that if you look at a pressure distribution around a
cowling nose, it generally shows low pressure above the prop centerline.
I think that implies that the left intake should be more problematic
than the right with normal Lycoming prop rotation. Perhaps the more aft
cylinder positioning helps on the left side. Anyway if I were going to
open up the inlets, I'd try to open them up below the prop, or even
sideways, instead of above the prop if at all possible. Just theory on
my part but sometimes the theories work :)

Ken

Walter Klatt wrote:
If you search back in the archives, you will find that
I and a few others have had a lot of cooling problems
with the 0320 and the fibreglass cowl.

I have a baffle in front that ramps the air up from the
inlet to more than half way up the cylinder. Also, I
have cut back the inlet lips and smoothed them up to
the cowl top.

If I were doing my cowl over, I would also make the
inlets bigger overall, as I know a couple of local guys
here have done to solve the cooling problem. This is on
floats. On wheels it is OK, but floats slows it down
just enough, and of course, you have to climb longer at
full power to get up to altitude, so on climb it just
heats up more than you want.

I have done everything possible with the outlets, as
has been described on this list, and it is still just
barely acceptable. I just think there isn't enough
getting in the front. When I look at a 172 or 180, they
have about 3 times as much inlet area as this cowl.

I might mention that this was with the Warp Drive prop.
Now with my Sensenich, it is definitely running about
50 degrees F cooler, but it is also winter now.

Never had a problem with oil cooling, just CHT's. In
fact right now, I have 2/3 of my cooler taped off to
make it run warmer.

Walter

-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
rebel@dcsol.com
Sent: Friday, January 10, 2003 9:43 AM
To: murphy-rebel@dcsol.com
Subject: Rebel cowl mods


Has anyone modified the cowling inlets for
the Rebel speed cowl? The #1
cylinder (Lycoming) is about 3" back from
the front of the cowling. It looks as
though the air wants to hit the baffle and
bounce right back out. Someone has
published info about the inlet air wanting
to come back out near the prop hub
and now I can see why. I plan to modify the
inlet so that there is a smoother
transition for the inlet air. If anyone has
done this already I would like to
see their work. My plan is to fiberglass a
ramp up to within 1" of the cylinder
and then rivet a piece of silicone baffle
seal onto the ramp. The silicone
baffle seal will rest right up against the
cylinder fins and will curl upwards.
I never liked the "comb" look of the
aluminum baffle after it has sat on the
fins and cut into the baffle.
If you look at some of the RV's you will see
how they use a baffle in the front
center of the engine to contain the air and
force it out through the cyl fins.
I plan to add that on my Rebel also. Any
comments will be appreciated.
Good luck, you'll need it and more
Rick D
Rebel 404R (trying to finish engine baffling)



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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by rebel
Thanks for your inputs. It looks as though I'm on the right track. Walter, if
you look at my modified cowling pictures at this site (Rick DeCiero-cowling
mods)you will see that I have already dealt with the exit air problem. That
should help a lot. If you have some pictures of your modifications please
post them if possible.
I will go back to the Bingiles books again to see if I've missed any of his
comments. What would we do without those great books? Thanks TONY! I wish I
had been able to thank him prersonally.
Over the holidays I was able to finally figure out how to get my camcorder to
dump pictures into the computer. With a "FIREWIRE" card added to the computer
all I need to do is, 1-record video of the subject, 2-plug the camcorder into
the FIREWIRE card, 3-play the camcorder in VCR mode and pause it when I have
an image that I want to use and click on the appropriate button for image
taking. 4-Save the image. It is now very easy for me to get pictures out to
the world. If you have specific areas of my Rebel that you need a picture of,
let me know and I will try to post it for you. Be aware that the airplane is
almost complete and pictures of final assemblies are about all that I can
provide.

Good luck, you'll need it,
Rick D.
Rebel S/N 404R




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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Walter Klatt
Rick, your exit looks good, and should work well, on
wheels for sure. However, I have been there with mine,
and had to enlarge it even further (similar shape) to
maximize the airflow. I need to update my website one
of these years, so I don't have any good photos to
show. Here's one from MAM's site with my plane at
Arlington. If you look carefully you will see that it
is quite big. Some locals at my airport here call it my
chinstrap.
http://www.murphyair.com/images/Arling02/Klatt.htm
This was about my 4th iteration, each slightly larger.
As I said, it now works, but just barely acceptable.
Bear in mind, I am talking about fully loaded on floats
in 30+ C summer heat and long climbs. Normal conditions
and on wheels are OK.

Like I said, if I was still at the cowl fitting stage,
I would make the inlets larger, too.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
rebel@dcsol.com
Sent: Saturday, January 11, 2003 7:12 AM
To: murphy-rebel@dcsol.com
Subject: Re: Rebel cowl mods


Thanks for your inputs. It looks as though
I'm on the right track. Walter, if
you look at my modified cowling pictures at
this site (Rick DeCiero-cowling
mods)you will see that I have already dealt
with the exit air problem. That
should help a lot. If you have some pictures
of your modifications please
post them if possible.
I will go back to the Bingiles books again
to see if I've missed any of his
comments. What would we do without those
great books? Thanks TONY! I wish I
had been able to thank him prersonally.
Over the holidays I was able to finally
figure out how to get my camcorder to
dump pictures into the computer. With a
"FIREWIRE" card added to the computer
all I need to do is, 1-record video of the
subject, 2-plug the camcorder into
the FIREWIRE card, 3-play the camcorder in
VCR mode and pause it when I have
an image that I want to use and click on the
appropriate button for image
taking. 4-Save the image. It is now very
easy for me to get pictures out to
the world. If you have specific areas of my
Rebel that you need a picture of,
let me know and I will try to post it for
you. Be aware that the airplane is
almost complete and pictures of final
assemblies are about all that I can
provide.

Good luck, you'll need it,
Rick D.
Rebel S/N 404R



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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by rebel
Walter,
I have no plans for floats but you never know that water flying sure looks
like fun. Your exit opening looks similar to the one posted here under Howard
Hanford's. My exit was a lot of work but it came out clean looking. There is
a picture of some low openings on a cowling on page 95 (upper right)of "The
Sportplane Builder". Ken had mentioned the extended lip.The author is talking
about the right side cylinder as you look aft. This would be the #2 on a
Lycoming and you always reference left or right as viewed from the drivers
(pilot) seat. My interpertation of the text is that the author saw an
extended lip on the upper portion of the cowl to catch the air as it was
dragged up by the prop.(unless the Franklin turns CCW (from cockpit)). Air
rally does some funny stuff in the front of an engine. The pictures of some
prop tuff testing are shown on this site.
MAM gave me the wrong templates for the baffles. Maybe they never produced
them for the Dynafocal mount and thought I would'nt notice. Another "Murphy
Mine" as Geert would say. An old set from a C172 is working out well as
templates. That left rear baffle is a challange. A coulple of more weeks
should see me with finished baffles. The cowl mods will have to wait for
warmer weather.
Good luck, you'll need it and a lot more, and please don't tell me it's worth
it. (humor)
Rick D.
Rebel S/N 404R
-> Rick, your exit looks good, and should work well, on
-> wheels for sure. However, I have been there with mine,
-> and had to enlarge it even further (similar shape) to
-> maximize the airflow. I need to update my website one
-> of these years, so I don't have any good photos to
-> show. Here's one from MAM's site with my plane at
-> Arlington. If you look carefully you will see that it
-> is quite big. Some locals at my airport here call it my
-> chinstrap.
-> http://www.murphyair.com/images/Arling02/Klatt.htm
-> This was about my 4th iteration, each slightly larger.
-> As I said, it now works, but just barely acceptable.
-> Bear in mind, I am talking about fully loaded on floats
-> in 30+ C summer heat and long climbs. Normal conditions
-> and on wheels are OK.
->
-> Like I said, if I was still at the cowl fitting stage,
-> I would make the inlets larger, too.
->
-> Walter




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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Walter Klatt
Thanks Ken. An upper lip on the inlet is a new idea
I've not heard about yet. I don't have that book,
sounds like a good one. Maybe I'll try to find a copy.
At least I have another thing to try.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
rebel@dcsol.com
Sent: Saturday, January 11, 2003 4:54 PM
To: murphy-rebel@dcsol.com
Subject: RE: Rebel cowl mods


Walter,
I have no plans for floats but you never
know that water flying sure looks
like fun. Your exit opening looks similar to
the one posted here under Howard
Hanford's. My exit was a lot of work but it
came out clean looking. There is
a picture of some low openings on a cowling
on page 95 (upper right)of "The
Sportplane Builder". Ken had mentioned the
extended lip.The author is talking
about the right side cylinder as you look
aft. This would be the #2 on a
Lycoming and you always reference left or
right as viewed from the drivers
(pilot) seat. My interpertation of the text
is that the author saw an
extended lip on the upper portion of the
cowl to catch the air as it was
dragged up by the prop.(unless the Franklin
turns CCW (from cockpit)). Air
rally does some funny stuff in the front of
an engine. The pictures of some
prop tuff testing are shown on this site.
MAM gave me the wrong templates for the
baffles. Maybe they never produced
them for the Dynafocal mount and thought I
would'nt notice. Another "Murphy
Mine" as Geert would say. An old set from a
C172 is working out well as
templates. That left rear baffle is a
challange. A coulple of more weeks
should see me with finished baffles. The
cowl mods will have to wait for
warmer weather.
Good luck, you'll need it and a lot more,
and please don't tell me it's worth
it. (humor)
Rick D.
Rebel S/N 404R
-> Rick, your exit looks good, and should
work well, on
-> wheels for sure. However, I have been
there with mine,
-> and had to enlarge it even further
(similar shape) to
-> maximize the airflow. I need to update my
website one
-> of these years, so I don't have any good photos to
-> show. Here's one from MAM's site with my plane at
-> Arlington. If you look carefully you will
see that it
-> is quite big. Some locals at my airport
here call it my
-> chinstrap.
-> http://www.murphyair.com/images/Arling02/Klatt.htm
-> This was about my 4th iteration, each
slightly larger.
-> As I said, it now works, but just barely
acceptable.
-> Bear in mind, I am talking about fully
loaded on floats
-> in 30+ C summer heat and long climbs.
Normal conditions
-> and on wheels are OK.
->
-> Like I said, if I was still at the cowl
fitting stage,
-> I would make the inlets larger, too.
->
-> Walter



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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Drew Dalgleish
A freind did extensive cowl mods to a cessna 150 aerobat including an upper
lip on the intake.
The change he said made the most improvement was a lenghthwise baffle along
the top of the engine case. He claimed it greatly reduced the turbulance on
top of the engine. When he was finished he had reduced the intake openings
to less than half of their origional size.
Drew


At 05:07 PM 1/11/2003 -0800, you wrote:
Thanks Ken. An upper lip on the inlet is a new idea
I've not heard about yet. I don't have that book,
sounds like a good one. Maybe I'll try to find a copy.
At least I have another thing to try.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
rebel@dcsol.com
Sent: Saturday, January 11, 2003 4:54 PM
To: murphy-rebel@dcsol.com
Subject: RE: Rebel cowl mods


Walter,
I have no plans for floats but you never
know that water flying sure looks
like fun. Your exit opening looks similar to
the one posted here under Howard
Hanford's. My exit was a lot of work but it
came out clean looking. There is
a picture of some low openings on a cowling
on page 95 (upper right)of "The
Sportplane Builder". Ken had mentioned the
extended lip.The author is talking
about the right side cylinder as you look
aft. This would be the #2 on a
Lycoming and you always reference left or
right as viewed from the drivers
(pilot) seat. My interpertation of the text
is that the author saw an
extended lip on the upper portion of the
cowl to catch the air as it was
dragged up by the prop.(unless the Franklin
turns CCW (from cockpit)). Air
rally does some funny stuff in the front of
an engine. The pictures of some
prop tuff testing are shown on this site.
MAM gave me the wrong templates for the
baffles. Maybe they never produced
them for the Dynafocal mount and thought I
would'nt notice. Another "Murphy
Mine" as Geert would say. An old set from a
C172 is working out well as
templates. That left rear baffle is a
challange. A coulple of more weeks
should see me with finished baffles. The
cowl mods will have to wait for
warmer weather.
Good luck, you'll need it and a lot more,
and please don't tell me it's worth
it. (humor)
Rick D.
Rebel S/N 404R
-> Rick, your exit looks good, and should
work well, on
-> wheels for sure. However, I have been
there with mine,
-> and had to enlarge it even further
(similar shape) to
-> maximize the airflow. I need to update my
website one
-> of these years, so I don't have any good photos to
-> show. Here's one from MAM's site with my plane at
-> Arlington. If you look carefully you will
see that it
-> is quite big. Some locals at my airport
here call it my
-> chinstrap.
-> http://www.murphyair.com/images/Arling02/Klatt.htm
-> This was about my 4th iteration, each
slightly larger.
-> As I said, it now works, but just barely
acceptable.
-> Bear in mind, I am talking about fully
loaded on floats
-> in 30+ C summer heat and long climbs.
Normal conditions
-> and on wheels are OK.
->
-> Like I said, if I was still at the cowl
fitting stage,
-> I would make the inlets larger, too.
->
-> Walter



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UNSUBSCRIBE murphy-rebel in the message body
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---------------------------------------------
------------------------



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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Walter Klatt
Hmmm, this makes me wonder if there is any merit in
sanding the inside top of the cowl to reduce turbulence
in there and maybe speed up the airflow. I did that
with the inlet areas to provide a smooth transition to
the cowl top, but not the whole thing.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Drew Dalgleish
Sent: Saturday, January 11, 2003 5:44 PM
To: murphy-rebel@dcsol.com
Subject: RE: Rebel cowl mods


A freind did extensive cowl mods to a cessna
150 aerobat including an upper
lip on the intake.
The change he said made the most improvement
was a lenghthwise baffle along
the top of the engine case. He claimed it
greatly reduced the turbulance on
top of the engine. When he was finished he
had reduced the intake openings
to less than half of their origional size.
Drew


At 05:07 PM 1/11/2003 -0800, you wrote:
Thanks Ken. An upper lip on the inlet is a new idea
I've not heard about yet. I don't have that book,
sounds like a good one. Maybe I'll try to
find a copy.
At least I have another thing to try.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
rebel@dcsol.com
Sent: Saturday, January 11, 2003 4:54 PM
To: murphy-rebel@dcsol.com
Subject: RE: Rebel cowl mods


Walter,
I have no plans for floats but you never
know that water flying sure looks
like fun. Your exit opening looks similar to
the one posted here under Howard
Hanford's. My exit was a lot of work but it
came out clean looking. There is
a picture of some low openings on a cowling
on page 95 (upper right)of "The
Sportplane Builder". Ken had mentioned the
extended lip.The author is talking
about the right side cylinder as you look
aft. This would be the #2 on a
Lycoming and you always reference left or
right as viewed from the drivers
(pilot) seat. My interpertation of the text
is that the author saw an
extended lip on the upper portion of the
cowl to catch the air as it was
dragged up by the prop.(unless the Franklin
turns CCW (from cockpit)). Air
rally does some funny stuff in the front of
an engine. The pictures of some
prop tuff testing are shown on this site.
MAM gave me the wrong templates for the
baffles. Maybe they never produced
them for the Dynafocal mount and thought I
would'nt notice. Another "Murphy
Mine" as Geert would say. An old set from a
C172 is working out well as
templates. That left rear baffle is a
challange. A coulple of more weeks
should see me with finished baffles. The
cowl mods will have to wait for
warmer weather.
Good luck, you'll need it and a lot more,
and please don't tell me it's worth
it. (humor)
Rick D.
Rebel S/N 404R
-> Rick, your exit looks good, and should
work well, on
-> wheels for sure. However, I have been
there with mine,
-> and had to enlarge it even further
(similar shape) to
-> maximize the airflow. I need to update my
website one
-> of these years, so I don't have any
good photos to
-> show. Here's one from MAM's site with
my plane at
-> Arlington. If you look carefully you will
see that it
-> is quite big. Some locals at my airport
here call it my
-> chinstrap.
->
http://www.murphyair.com/images/Arling02/Klatt.htm
-> This was about my 4th iteration, each
slightly larger.
-> As I said, it now works, but just barely
acceptable.
-> Bear in mind, I am talking about fully
loaded on floats
-> in 30+ C summer heat and long climbs.
Normal conditions
-> and on wheels are OK.
->
-> Like I said, if I was still at the cowl
fitting stage,
-> I would make the inlets larger, too.
->
-> Walter



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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Wayne G. O'Shea
Howard filled his in with fiberglass from the inlet hole lip to the cowl
inner top (forming an upside down ramp) to give a smoother air flow at the
inlets with a slight improvement in CHT temperatures.

Wayne

----- Original Message -----
From: "Walter Klatt" <walter.klatt@shaw.ca>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, January 12, 2003 12:25 PM
Subject: RE: Rebel cowl mods

Hmmm, this makes me wonder if there is any merit in
sanding the inside top of the cowl to reduce turbulence
in there and maybe speed up the airflow. I did that
with the inlet areas to provide a smooth transition to
the cowl top, but not the whole thing.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Drew Dalgleish
Sent: Saturday, January 11, 2003 5:44 PM
To: murphy-rebel@dcsol.com
Subject: RE: Rebel cowl mods


A freind did extensive cowl mods to a cessna
150 aerobat including an upper
lip on the intake.
The change he said made the most improvement
was a lenghthwise baffle along
the top of the engine case. He claimed it
greatly reduced the turbulance on
top of the engine. When he was finished he
had reduced the intake openings
to less than half of their origional size.
Drew


At 05:07 PM 1/11/2003 -0800, you wrote:
Thanks Ken. An upper lip on the inlet is a new idea
I've not heard about yet. I don't have that book,
sounds like a good one. Maybe I'll try to
find a copy.
At least I have another thing to try.

Walter
good photos to
my plane at
http://www.murphyair.com/images/Arling02/Klatt.htm

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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Brian Cross
The ramp that Wayne is referring to is standard on the RV aircraft &
spelled in on their drawings. They just glass in a ramp to go from the top
of the inlet to the underside of the upper portion of the cowl. I think
that is a very logical step as otherwise, turbulence will surely result
there & presume total CFM into the cowl would be reduced.

Brian #328R


At 12:31 PM 01/12/2003 -0500, you wrote:
Howard filled his in with fiberglass from the inlet hole lip to the cowl
inner top (forming an upside down ramp) to give a smoother air flow at the
inlets with a slight improvement in CHT temperatures.

Wayne

----- Original Message -----
From: "Walter Klatt" <walter.klatt@shaw.ca>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, January 12, 2003 12:25 PM
Subject: RE: Rebel cowl mods

Hmmm, this makes me wonder if there is any merit in
sanding the inside top of the cowl to reduce turbulence
in there and maybe speed up the airflow. I did that
with the inlet areas to provide a smooth transition to
the cowl top, but not the whole thing.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Drew Dalgleish
Sent: Saturday, January 11, 2003 5:44 PM
To: murphy-rebel@dcsol.com
Subject: RE: Rebel cowl mods


A freind did extensive cowl mods to a cessna
150 aerobat including an upper
lip on the intake.
The change he said made the most improvement
was a lenghthwise baffle along
the top of the engine case. He claimed it
greatly reduced the turbulance on
top of the engine. When he was finished he
had reduced the intake openings
to less than half of their origional size.
Drew


At 05:07 PM 1/11/2003 -0800, you wrote: find a copy. good photos to my plane at http://www.murphyair.com/images/Arling02/Klatt.htm ------------------------- list-server@dcsol.com with body on a line by itself. mike.davis@dcsol.com -------------------------
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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by Walter Klatt
I've done that on mine, but am wondering if it also
might be worth sanding smooth the rest of the underside
of the top cowl, to make for smoother airflow.
Afterall, I don't hear of any cooling problems with the
aluminium cowl planes, and maybe that is part of the
difference, too.

Walter
-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Brian Cross
Sent: Sunday, January 12, 2003 2:39 PM
To: murphy-rebel@dcsol.com
Subject: Re: Rebel cowl mods


The ramp that Wayne is referring to is
standard on the RV aircraft &
spelled in on their drawings. They just
glass in a ramp to go from the top
of the inlet to the underside of the upper
portion of the cowl. I think
that is a very logical step as otherwise,
turbulence will surely result
there & presume total CFM into the cowl
would be reduced.

Brian #328R


At 12:31 PM 01/12/2003 -0500, you wrote:
Howard filled his in with fiberglass from
the inlet hole lip to the cowl
inner top (forming an upside down ramp) to
give a smoother air flow at the
inlets with a slight improvement in CHT
temperatures.
Wayne

----- Original Message -----
From: "Walter Klatt" <walter.klatt@shaw.ca>
To: <murphy-rebel@dcsol.com>
Sent: Sunday, January 12, 2003 12:25 PM
Subject: RE: Rebel cowl mods

Hmmm, this makes me wonder if there is
any merit in
sanding the inside top of the cowl to
reduce turbulence
in there and maybe speed up the airflow.
I did that
with the inlet areas to provide a smooth
transition to
the cowl top, but not the whole thing.

Walter
is a new idea
have that book,
http://www.murphyair.com/images/Arling02/Klatt.htm
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Rebel cowl mods

Posted: Fri Feb 17, 2012 10:42 pm
by rebel
Thanks for those suggestions. I had not considered those internal upper ramps
but it does make sense and should help a great deal. One of the photo's in
the Rebel cowl files shows a cowl with these ramps but I thought it was the
bottom cowl and that just did not make sense. A closer rewiew of the photo
(COWL4 by S. Sloan) shows that this is the upper cowl with glassed in ramps.
Good luck, you'll need it,
Rick D. 404R

On 1/12/03 3:27 PM, BCROSS2160@ROGERS.COM wrote to MURPHY-REBEL:

-> Date: Sun, 12 Jan 2003 17:39:02 -0500
-> To: <murphy-rebel@dcsol.com>
-> From: Brian Cross <bcross2160@rogers.com>
-> Subject: Re: Rebel cowl mods
-> The ramp that Wayne is referring to is standard on the RV aircraft &
-> spelled in on their drawings. They just glass in a ramp to go from the
top
-> of the inlet to the underside of the upper portion of the cowl. I think
-> that is a very logical step as otherwise, turbulence will surely result
-> there & presume total CFM into the cowl would be reduced.
->
-> Brian #328R
->
->
-> At 12:31 PM 01/12/2003 -0500, you wrote:
-> >Howard filled his in with fiberglass from the inlet hole lip to the cowl
-> >inner top (forming an upside down ramp) to give a smoother air flow at the
-> >inlets with a slight improvement in CHT temperatures.
-> >
-> >Wayne
-> >





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