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jose_m_toro(at)yahoo.com
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 Posted: Fri Nov 25, 2011 5:38 pm Post subject: CHT still high after cowling modification (test flight witho |
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I'm considering to do a short flight tomorrow without cowling to verify the modified needles (main jet: 2.20-> 2.49, needle jet: 2.76-> 2.87) and to try to proof my theory about insufficient air going into the cooling baffels. Is it there any reason why I should not fly without the cowling? I was checking the Jabiru powered X-Airs (tractor without cowling), and they use the same kind of cooling baffle that I use.
Jose
Rans S6ES/Jab 2200
From: Jose M. Toro <jose_m_toro(at)yahoo.com>
To: Jose Toro <jose_m_toro(at)yahoo.com>
Sent: Thursday, November 24, 2011 9:51 PM
Subject: Fw: JabiruEngine-List: Re: CHT still high after cowling modification (jets size?)
----- Forwarded Message -----
From: dons701 <burdon1(at)comcast.net>
To: jabiruengine-list(at)matronics.com
Sent: Thursday, November 24, 2011 11:18 AM
Subject: Re: CHT still high after cowling modification (jets size?)
--> JabiruEngine-List message posted by: "dons701" <burdon1(at)comcast.net (burdon1(at)comcast.net)>
Hi Jose. The purpose of the holes is to bleed some cooling air over the front crank bearing, but you can duct tape them closed as an experiment. I found gaps around the bottom perimeter of my ducts where air could leak and not flow through the fins so I filled these gaps with strips of high temp foam silicone rubber glued to the duct. Then, you can remove the tape from the holes.
I remember your peak head temp being 400F. If true, that alone can raise oil temperature. But, having peak egt's at 1500F tends to conduct to the head and it's thermocouple.....Which increases oil temps.
Did you pull any spark plugs for color check??
It is easy to change your main jet, it requires an 8mm box wrench I believe and be sure to have a good magnifying glass handy to see the jet number! I would not be afraid of a #240 or a #245 main jet, even with the #276 needle jet and it's "matching" needle as supplied with your carb. Make sure there is a brass flat washer behind the jet. It's there to prevent cavitation of air, (whirlpool) into fuel around jet body, supposedly. Fuel level should be close to 12mm from the top when bowl is carefully lowered, (not easy without spilling).
Questions;
What is your peak RPM and EGT, full throttle, climb out?
What is your EGT at cruise RPM, part throttle at say around 2800RPM?
What type of temperature measurement system are you using? EIS? Single analog, digital? Individual cylinder capability? Or group measurement?
My thoughts are, get full throttle EGT's to 1200F to 1225F.
Cruise EGT's, if around 2800 or so, around 1325F.
Once you get these temps under control, the demand being placed on your "cooling systems" will be greatly reduced.
Hope this helps....DonB
--------
Zenith 701 #76120
Jabiru 2200A #2456 95 hours
Sensenich Wood 64-PJ-36 Prop
Read this topic online here:
http://forums.matronics.com/viewt * AeroElectric
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pete(at)usjabiru.com
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| Posted: Mon Nov 28, 2011 8:12 am Post subject: CHT still high after cowling modification (test flight witho |
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The only way you can cool the cylinders is to get high pressure air above and low pressure below the cylinders. The cowl design is responsible for creating this difference. How will you create the pressure differential without a cowl? The ram air ducts by themselves will not do it as several customers have found out to their dismay after achieving 500 degree CHT’s in the initial climb out on a short flight. No worries, though. New heads are available to replace the warped ones.
Pete
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Jose M. Toro
Sent: Friday, November 25, 2011 7:36 PM
To: jabiruengines list
Subject: Re: Re: CHT still high after cowling modification (test flight without cowling?)
I'm considering to do a short flight tomorrow without cowling to verify the modified needles (main jet: 2.20-> 2.49, needle jet: 2.76-> 2.87) and to try to proof my theory about insufficient air going into the cooling baffels. Is it there any reason why I should not fly without the cowling? I was checking the Jabiru powered X-Airs (tractor without cowling), and they use the same kind of cooling baffle that I use.
Jose
Rans S6ES/Jab 2200
From: Jose M. Toro <jose_m_toro(at)yahoo.com>
To: Jose Toro <jose_m_toro(at)yahoo.com>
Sent: Thursday, November 24, 2011 9:51 PM
Subject: Fw: Re: CHT still high after cowling modification (jets size?)
----- Forwarded Message -----
From: dons701 <burdon1(at)comcast.net>
To: jabiruengine-list(at)matronics.com
Sent: Thursday, November 24, 2011 11:18 AM
Subject: Re: CHT still high after cowling modification (jets size?)
--> JabiruEngine-List message posted by: "dons701" <burdon1(at)comcast.net (burdon1(at)comcast.net)>
Hi Jose. The purpose of the holes is to bleed some cooling air over the front crank bearing, but you can duct tape them closed as an experiment. I found gaps around the bottom perimeter of my ducts where air could leak and not flow through the fins so I filled these gaps with strips of high temp foam silicone rubber glued to the duct. Then, you can remove the tape from the holes.
I remember your peak head temp being 400F. If true, that alone can raise oil temperature. But, having peak egt's at 1500F tends to conduct to the head and it's thermocouple.....Which increases oil temps.
Did you pull any spark plugs for color check??
It is easy to change your main jet, it requires an 8mm box wrench I believe and be sure to have a good magnifying glass handy to see the jet number! I would not be afraid of a #240 or a #245 main jet, even with the #276 needle jet and it's "matching" needle as supplied with your carb. Make sure there is a brass flat washer behind the jet. It's there to prevent cavitation of air, (whirlpool) into fuel around jet body, supposedly. Fuel level should be close to 12mm from the top when bowl is carefully lowered, (not easy without spilling).
Questions;
What is your peak RPM and EGT, full throttle, climb out?
What is your EGT at cruise RPM, part throttle at say around 2800RPM?
What type of temperature measurement system are you using? EIS? Single analog, digital? Individual cylinder capability? Or group measurement?
My thoughts are, get full throttle EGT's to 1200F to 1225F.
Cruise EGT's, if around 2800 or so, around 1325F.
Once you get these temps under control, the demand being placed on your "cooling systems" will be greatly reduced.
Hope this helps....DonB
--------
Zenith 701 #76120
Jabiru 2200A #2456 95 hours
Sensenich Wood 64-PJ-36 Prop
Read this topic online here:
http://forums.matronics.com/viewt * AeroElectric http://www.matronics.com/chref="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/contribution ===========
[quote][b]
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nick(at)flylightning.net
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| Posted: Mon Nov 28, 2011 8:43 am Post subject: CHT still high after cowling modification (test flight witho |
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Jose,
I would not fly that aircraft with out a cowl. To do so will be dangerous. The flat area of the firewall is not intended to be aerodynamic and will result in much higher stall speed, and certainly a much higher approach speed which you may not account for. The S6 has a broad enough firewall face to cause many other ill wanted flight characteristics that I do not care to get into.
The problem is airflow thru the cowl. Inlet to exit size ratios, air-duct installation or something else, but flying the aircraft with no cowl will only prove that you have just become a test pilot when you certainly did not want to.
Nick Otterback
Research and Design
Arion Aircraft LLC
--
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
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jose_m_toro(at)yahoo.com
Guest
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| Posted: Mon Nov 28, 2011 8:56 am Post subject: CHT still high after cowling modification (test flight witho |
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Pete:
I decided Not to fly without cowling. However, for educational purposes, why it works in the X-air? What is different in that installation?
Have you seen the latest pictures I posted in the list? I arrived to the conclusion that the top of the cowling entrances were aligned too low in relation to the top of the cylinders. So, the next step of my "project" is to raise the top of the entrances about an inch. It will take minor modifications to the cooling baffles for coupling purposes. Will also modify the bottom of the cowling to close the entrance. The objective is to route the air flow to the upper half of the cylinders.
After modifying the carb needles, I started the engine briefly without cowling. At idle, I observed the temperature in the front cylinder 30 deg higher than the rear one. Being the cowling out the equation, I wonder if there is a problem with the position of the deflector inside the cooling baffles. (I posted a picture of booth cooling baffles). It points the air flow approximately to the middle of the rear cylinder. Should I move this deflector forward?
Jose
Sent from my iPhone
On Nov 28, 2011, at 12:09 PM, "Pete Krotje" <pete(at)usjabiru.com (pete(at)usjabiru.com)> wrote:
[quote]v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} <![endif]--> <![endif]--> <![endif]-->
The only way you can cool the cylinders is to get high pressure air above and low pressure below the cylinders. The cowl design is responsible for creating this difference. How will you create the pressure differential without a cowl? The ram air ducts by themselves will not do it as several customers have found out to their dismay after achieving 500 degree CHT’s in the initial climb out on a short flight. No worries, though. New heads are available to replace the warped ones.
Pete
From: owner-jabiruengine-list-server(at)matronics.com (owner-jabiruengine-list-server(at)matronics.com) [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Jose M. Toro
Sent: Friday, November 25, 2011 7:36 PM
To: jabiruengines list
Subject: Re: Re: CHT still high after cowling modification (test flight without cowling?)
I'm considering to do a short flight tomorrow without cowling to verify the modified needles (main jet: 2.20-> 2.49, needle jet: 2.76-> 2.87) and to try to proof my theory about insufficient air going into the cooling baffels. Is it there any reason why I should not fly without the cowling? I was checking the Jabiru powered X-Airs (tractor without cowling), and they use the same kind of cooling baffle that I use.
Jose
Rans S6ES/Jab 2200
From: Jose M. Toro <jose_m_toro(at)yahoo.com (jose_m_toro(at)yahoo.com)>
To: Jose Toro <jose_m_toro(at)yahoo.com (jose_m_toro(at)yahoo.com)>
Sent: Thursday, November 24, 2011 9:51 PM
Subject: Fw: Re: CHT still high after cowling modification (jets size?)
----- Forwarded Message -----
From: dons701 <burdon1(at)comcast.net (burdon1(at)comcast.net)>
To: jabiruengine-list(at)matronics.com (jabiruengine-list(at)matronics.com)
Sent: Thursday, November 24, 2011 11:18 AM
Subject: JabiruEngine-List: Re: CHT still high after cowling modification (jets size?)
--> JabiruEngine-List message posted by: "dons701" <burdon1(at)comcast.net (burdon1(at)comcast.net)>
Hi Jose. The purpose of the holes is to bleed some cooling air over the front crank bearing, but you can duct tape them closed as an experiment. I found gaps around the bottom perimeter of my ducts where air could leak and not flow through the fins so I filled these gaps with strips of high temp foam silicone rubber glued to the duct. Then, you can remove the tape from the holes.
I remember your peak head temp being 400F. If true, that alone can raise oil temperature. But, having peak egt's at 1500F tends to conduct to the head and it's thermocouple.....Which increases oil temps.
Did you pull any spark plugs for color check??
It is easy to change your main jet, it requires an 8mm box wrench I believe and be sure to have a good magnifying glass handy to see the jet number! I would not be afraid of a #240 or a #245 main jet, even with the #276 needle jet and it's "matching" needle as supplied with your carb. Make sure there is a brass flat washer behind the jet. It's there to prevent cavitation of air, (whirlpool) into fuel around jet body, supposedly. Fuel level should be close to 12mm from the top when bowl is carefully lowered, (not easy without spilling).
Questions;
What is your peak RPM and EGT, full throttle, climb out?
What is your EGT at cruise RPM, part throttle at say around 2800RPM?
What type of temperature measurement system are you using? EIS? Single analog, digital? Individual cylinder capability? Or group measurement?
My thoughts are, get full throttle EGT's to 1200F to 1225F.
Cruise EGT's, if around 2800 or so, around 1325F.
Once you get these temps under control, the demand being placed on your "cooling systems" will be greatly reduced.
Hope this helps...DonB
--------
Zenith 701 #76120
Jabiru 2200A #2456 95 hours
Sensenich Wood 64-PJ-36 Prop
Read this topic online here:
http://forums.matronics.com/viewt * AeroElectric [/url][url=http://www.matronics.com/contribution]http://www.matronics.com/chref="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/contribution ===========
| Quote: |
===================================
ctric.com
| Quote: | www.buildersbooks.com
uilthelp.com
|
matronics.com/contribution
===================================
st">http://www.matronics.com/Navigator?JabiruEngine-List
===================================
cs.com
===================================
matronics.com/contribution
===================================
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[b]
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http://www.matronics.com/Navigator?JabiruEngine-List |
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jose_m_toro(at)yahoo.com
Guest
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| Posted: Mon Nov 28, 2011 9:01 am Post subject: CHT still high after cowling modification (test flight witho |
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Nick: Thanks for the advice. I will not fly without cowling. Could you take a look at my latest posting and tell me your opinion?
Thanks!
Jose
Sent from my iPhone
On Nov 28, 2011, at 12:39 PM, "nick " <nick(at)flylightning.net (nick(at)flylightning.net)> wrote:
[quote] v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} <![endif]--> <![endif]--> Clean Clean DocumentEmail MicrosoftInternetExplorer4 <![endif]--> st1\:*{behavior:url(#default#ieooui) } <![endif]--> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} <![endif]--> <![endif]--> <![endif]-->
Jose,
I would not fly that aircraft with out a cowl. To do so will be dangerous. The flat area of the firewall is not intended to be aerodynamic and will result in much higher stall speed, and certainly a much higher approach speed which you may not account for. The S6 has a broad enough firewall face to cause many other ill wanted flight characteristics that I do not care to get into.
The problem is airflow thru the cowl. Inlet to exit size ratios, air-duct installation or something else, but flying the aircraft with no cowl will only prove that you have just become a test pilot when you certainly did not want to.
Nick Otterback
Research and Design
Arion Aircraft LLC
--
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
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pete(at)usjabiru.com
Guest
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| Posted: Mon Nov 28, 2011 11:43 am Post subject: CHT still high after cowling modification (test flight witho |
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It doesn’t work particularly well on an X-Air unless additional steps are taken to make pressure under the cylinders lower than pressure inside the ducts.
Pete
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Jose M. Toro
Sent: Monday, November 28, 2011 10:54 AM
To: jabiruengine-list(at)matronics.com
Subject: Re: Re: CHT still high after cowling modification (test flight without cowling?)
Pete:
I decided Not to fly without cowling. However, for educational purposes, why it works in the X-air? What is different in that installation?
Have you seen the latest pictures I posted in the list? I arrived to the conclusion that the top of the cowling entrances were aligned too low in relation to the top of the cylinders. So, the next step of my "project" is to raise the top of the entrances about an inch. It will take minor modifications to the cooling baffles for coupling purposes. Will also modify the bottom of the cowling to close the entrance. The objective is to route the air flow to the upper half of the cylinders.
After modifying the carb needles, I started the engine briefly without cowling. At idle, I observed the temperature in the front cylinder 30 deg higher than the rear one. Being the cowling out the equation, I wonder if there is a problem with the position of the deflector inside the cooling baffles. (I posted a picture of booth cooling baffles). It points the air flow approximately to the middle of the rear cylinder. Should I move this deflector forward?
Jose
Sent from my iPhone
On Nov 28, 2011, at 12:09 PM, "Pete Krotje" <pete(at)usjabiru.com (pete(at)usjabiru.com)> wrote:
| Quote: |
The only way you can cool the cylinders is to get high pressure air above and low pressure below the cylinders. The cowl design is responsible for creating this difference. How will you create the pressure differential without a cowl? The ram air ducts by themselves will not do it as several customers have found out to their dismay after achieving 500 degree CHT’s in the initial climb out on a short flight. No worries, though. New heads are available to replace the warped ones.
Pete
From: owner-jabiruengine-list-server(at)matronics.com (owner-jabiruengine-list-server(at)matronics.com) [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Jose M. Toro
Sent: Friday, November 25, 2011 7:36 PM
To: jabiruengines list
Subject: Re: Re: CHT still high after cowling modification (test flight without cowling?)
I'm considering to do a short flight tomorrow without cowling to verify the modified needles (main jet: 2.20-> 2.49, needle jet: 2.76-> 2.87) and to try to proof my theory about insufficient air going into the cooling baffels. Is it there any reason why I should not fly without the cowling? I was checking the Jabiru powered X-Airs (tractor without cowling), and they use the same kind of cooling baffle that I use.
Jose
Rans S6ES/Jab 2200
From: Jose M. Toro <jose_m_toro(at)yahoo.com (jose_m_toro(at)yahoo.com)>
To: Jose Toro <jose_m_toro(at)yahoo.com (jose_m_toro(at)yahoo.com)>
Sent: Thursday, November 24, 2011 9:51 PM
Subject: Fw: Re: CHT still high after cowling modification (jets size?)
----- Forwarded Message -----
From: dons701 <burdon1(at)comcast.net (burdon1(at)comcast.net)>
To: jabiruengine-list(at)matronics.com (jabiruengine-list(at)matronics.com)
Sent: Thursday, November 24, 2011 11:18 AM
Subject: Re: CHT still high after cowling modification (jets size?)
--> JabiruEngine-List message posted by: "dons701" <burdon1(at)comcast.net (burdon1(at)comcast.net)>
Hi Jose. The purpose of the holes is to bleed some cooling air over the front crank bearing, but you can duct tape them closed as an experiment. I found gaps around the bottom perimeter of my ducts where air could leak and not flow through the fins so I filled these gaps with strips of high temp foam silicone rubber glued to the duct. Then, you can remove the tape from the holes.
I remember your peak head temp being 400F. If true, that alone can raise oil temperature. But, having peak egt's at 1500F tends to conduct to the head and it's thermocouple.....Which increases oil temps.
Did you pull any spark plugs for color check??
It is easy to change your main jet, it requires an 8mm box wrench I believe and be sure to have a good magnifying glass handy to see the jet number! I would not be afraid of a #240 or a #245 main jet, even with the #276 needle jet and it's "matching" needle as supplied with your carb. Make sure there is a brass flat washer behind the jet. It's there to prevent cavitation of air, (whirlpool) into fuel around jet body, supposedly. Fuel level should be close to 12mm from the top when bowl is carefully lowered, (not easy without spilling).
Questions;
What is your peak RPM and EGT, full throttle, climb out?
What is your EGT at cruise RPM, part throttle at say around 2800RPM?
What type of temperature measurement system are you using? EIS? Single analog, digital? Individual cylinder capability? Or group measurement?
My thoughts are, get full throttle EGT's to 1200F to 1225F.
Cruise EGT's, if around 2800 or so, around 1325F.
Once you get these temps under control, the demand being placed on your "cooling systems" will be greatly reduced.
Hope this helps....DonB
--------
Zenith 701 #76120
Jabiru 2200A #2456 95 hours
Sensenich Wood 64-PJ-36 Prop
Read this topic online here:
http://forums.matronics.com/viewt * AeroElectric <="" a="">http://www.matronics.com/chref="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/contribution ===========
| Quote: | | ===================================ctric.com>www.buildersbooks.comuilthelp.commatronics.com/contribution===================================st">http://www.matronics.com/Navigator?JabiruEngine-List=================================== |
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