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punga-iwi(at)netspace.net
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 Posted: Wed Feb 20, 2008 7:11 pm Post subject: Cylinder cooling |
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In a message dated 2/20/2008 8:13:07 P.M. Eastern Standard Time,
allanmaxe(at)yahoo.com writes:
I ment cht
OK, Allen, then here are some thoughts on CHTs:
Remember the key to good cylinder cooling on the jabiru powered
Lightning or Esqual is high pressure on top of the cylinders and low
pressure under them. That makes sure the air flows from top to bottom
through the cooling fins and thus cools the cylinders. So make sure all
air coming in through the two nose bowl intakes can only go to the area
above the cylinders. Close up the area between the nose bowl and the
Jabiru supplied fiberglass intake ducts to insure all intake air only
goes into the fiberglass ducts. On the bottom cowl, to insure a lower
pressure, the Lightning cowl has a lip or "air dam" that creates a lower
pressure area inside the lower cowl. This also insures the cooling air
moves from top to bottom. I don't remember if the Esqual bottom cowl
has that or not since my airplane is total Lightning from firewall
forward. So if the Esqual does not have a lip on the bottom cowl, make
one using fiberglass or even aluminum. Once both of these things are
done, then you can fine tune the CHTs for individual cylinders by adding
small "deflectors" inside the fiberglass ducts over the cylinder than
needs more cooling. Start with these "eyebrow shaped" deflectors (so
they match up to the concave shape of the inside of the ducts) being
about three inches long by 3/8 inch deep. They trim them down if they
end up blocking too much air to the cylinder behind them. On my set up
I have two deflectors on each side over the middle and aft cylinders.
This "experimenting" is what home built aircraft is all about - kind of
trial and error.
I think the hottest cylinder that I ever see on N31BZ is around 320
during a climb out on a really hot 100 degree day here in Virginia. By
the time I am climbing through about 3000 feet the temp then starts back
down from the high of 320 or so. Cruise temps are all well below 300.
So we know the above will work.
As I mentioned in the previous e-mail. You really should attend the
Jabiru engine seminar. Certainly time and money well spent. You will
not only talk about this type of thing, but will get to actually see how
the small deflectors are glued inside the intake ducts.
Blue Skies,
Buz
------------------------------------------------------------------------
Delicious ideas to please the pickiest eaters. Watch the video on AOL
Living.
<http://living.aol.com/video/how-to-please-your-picky-eater/rachel-campos-duffy/2050827?NCID=aolcmp00300000002598>
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ddw55(at)hotmail.com
Guest
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| Posted: Thu Feb 21, 2008 5:31 am Post subject: Cylinder cooling |
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Buz,
a picture of the lip or "air dam" on the Lightning cowl would be nice  )
Danny
> Date: Thu, 21 Feb 2008 14:09:12 +1100
| Quote: | From: punga-iwi(at)netspace.net.au
To: lightning-list(at)matronics.com
Subject: Lightning-List: Cylinder cooling
--> Lightning-List message posted by: Fry <punga-iwi(at)netspace.net.au>
In a message dated 2/20/2008 8:13:07 P.M. Eastern Standard Time,
allanmaxe(at)yahoo.com writes:
I ment cht
OK, Allen, then here are some thoughts on CHTs:
Remember the key to good cylinder cooling on the jabiru powered
Lightning or Esqual is high pressure on top of the cylinders and low
pressure under them. That makes sure the air flows from top to bottom
through the cooling fins and thus cools the cylinders. So make sure all
air coming in through the two nose bowl intakes can only go to the area
above the cylinders. Close up the area between the nose bowl and the
Jabiru supplied fiberglass intake ducts to insure all intake air only
goes into the fiberglass ducts. On the bottom cowl, to insure a lower
pressure, the Lightning cowl has a lip or "air dam" that creates a lower
pressure area inside the lower cowl. This also insures the cooling air
moves from top to bottom. I don't remember if the Esqual bottom cowl
has that or not since my airplane is total Lightning from firewall
forward. So if the Esqual does not have a lip on the bottom cowl, make
one using fiberglass or even aluminum. Once both of these things are
done, then you can fine tune the CHTs for individual cylinders by adding
small "deflectors" inside the fiberglass ducts over the cylinder than
needs more cooling. Start with these "eyebrow shaped" deflectors (so
they match up to the concave shape of the inside of the ducts) being
about three inches long by 3/8 inch deep. They trim them down if they
end up blocking too much air to the cylinder behind them. On my set up
I have two deflectors on each side over the middle and aft cylinders.
This "experimenting" is what home built aircraft is all about - kind of
trial and error.
I think the hottest cylinder that I ever see on N31BZ is around 320
during a climb out on a really hot 100 degree day here in Virginia. By
the time I am climbing through about 3000 feet the temp then starts back
down from the high of 320 or so. Cruise temps are all well below 300.
So we know the above will work.
As I mentioned in the previous e-mail. You really should attend the
Jabiru engine seminar. Certainly time and money well spent. You will
not only talk about this type of thing, but will get to actually see how
the small deflectors are glued inside the intake ducts.
Blue Skies,
Buz
------------------------------------------------------------------------
Delicious ideas to please the pickiest eaters. Watch the video on AOL
Living.
<http://living.aol.com/video/how-to-please-your-picky-eater/rachel-campos-duffy/2050827?NCID=aolcmp00300000002598>
============
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Een gelukkig nieuwjaar vanwege Windows Live...Download het nu gratis! Windows Live [quote][b]
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N1BZRich(at)aol.com
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| Posted: Thu Feb 21, 2008 1:46 pm Post subject: Cylinder cooling |
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In a message dated 2/21/2008 8:32:45 A.M. Eastern Standard Time, ddw55(at)hotmail.com writes:
| Quote: | | a picture of the lip or "air dam" on the Lightning cowl would be nice |
Danny,
I have looked through my photo files and can not find one that shows the Lightning's bottom cowl. May have to take one the next time I remember to take my camera to the airport.
Sorry,
Buz
Delicious ideas to please the pickiest eaters. Watch the video on AOL Living.
[quote][b]
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Clive J
Joined: 03 Nov 2007
Posts: 340
Location: UK
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| Posted: Thu Feb 21, 2008 10:59 pm Post subject: Cylinder cooling |
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Here's one of Buz's Esqual's LS cowling, a bit grainy but shows the
cowling opening. It looks smaller than the Esqual which also has a lip.
How the actual airflow is affected with each, of course, would need
testing but anecdotal results just show the overall cooling package of
the Esqual is poor. This because the cowling was designed for the
Rotax.
Park my Esqual in a breeze after it's been running and there is plenty
of heat coming out the bottom of the cowl. I think cooling issues with
the Esqual is all around the front opening and the ducts. Just what Pete
and the guys changed with the Lightning cowlings. I think there will be
enough air flow out of the Esqual cowling opening it's just very tight
inside the ducts so that air will be 'choked' so the flow restricted.
One recent suggestion on the engine forum to improve 3300 cooling is to
modify the ducts like the type where the spark plugs and leads are
inside the ducts, this is as later 3300 engine ducts are. Whether we can
do this within the tight confines of the Esqual top cowling I don't
know. Will take a look next time I'm home.
Early 3300 engine in Jabiru's own J series planes also have cooling
issues and the cowlings were subsequently changed more like the
Lightning, though not as good it has to be said.
Regards, Clive
--
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