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Lynn Matteson
Joined: 10 Jan 2006 Posts: 2778 Location: Grass Lake, Michigan
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Posted: Sat May 28, 2011 12:35 pm Post subject: fun and games with a manometer |
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I built a U-tube water manometer this week, and finally got a chance
to try it out (flying) today. Prior to today, I had used it to find a
slight leak in my pitot system, which I fixed by tightening up the
Nylo-Seal fittings while watching the indicated leak disappear. Ever
wonder how much tightening is enough for those fittings? I have, and
now I know....just use a manometer on the system during the assembly
of the fittings, and you'll know when to quit tightening.
Today, I got a chance to fly briefly to test the Jabiru-dictated 2.4"
of water column difference between the inlet air ducts (each side
tested individually), and the exit-air area of the plane. I haven't
had any cooling problems, so I just wanted to test how close my
installation came to meeting that 2.4" measurement. My installation
was pretty close to right on the mark...it read about 2.3" to 2.6"
depending on the bounce of the water in the tube. Pretty happy with
that, I flew home to add a 1" lip to the bottom of my cowl exit. I
bent a 20" length of sheet aluminum to a 60� angle, letting 1" stick
out into the airstream below the cowl, and c-clamped it in place. (I
didn't want to rivet it in place just to test the theory.) I went up
and flew some more...windy day, didn't want to fly too much....and
now I saw about 2.5" to 3" on either of the two air ducts. But the
really interesting thing about the last test, was that I saw a mark
on the aluminum "lip" showing where it was contacting the left
exhaust pipe. Normally, this pipe cleared the cowl/lip by about 1/2",
but apparently during flight, my cowl flexes up enough to allow
contact with the exhaust pipe. No big deal you say, and I agree, but
if that lip is flexing up 1/2", what just happened to the carefully
engineered 3:1 ratio of exit air-to-inlet air that shouldn't change?
Kinda like having a wrong-way operating cowl flap for the exit air,
I'm thinking. So I need to stiffen up the lower cowl exit flange so
that it doesn't flex at all, and then do some more testing....maybe a
center support for the cowl is in order...something that will be
permanently attached to either the cowl or the airframe, but not
both, so as to allow for removing the cowl without having to deal
with another fastener down there.
If anybody's having trouble with overheating issues, yet you're sure
of the "correctness" of your installation, you might think about the
rigidity of things when air pressure gets applied.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with "Ramcharger" intake manifold...1110 hrs (since
3-27-2006)
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_________________ Lynn
Kitfox IV-Jabiru 2200
N369LM |
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7suds(at)Chartermi.net Guest
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Posted: Sat May 28, 2011 3:02 pm Post subject: fun and games with a manometer |
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Lynn,
Cool stuff, (no pun intended) how did you get the tubes fastened in the cowl
openings and did you run them into the cockpit? Look forward to hearing more
about the experiments.
Lloyd Cudnohufsky
5 Outback 912 IVO IFA
Northern Mi.
--
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lcfitt(at)sbcglobal.net Guest
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Posted: Sat May 28, 2011 4:52 pm Post subject: fun and games with a manometer |
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Sorry Lynn. Don't buy your experimentation. These forums are reserved for
opinions only.
Seriously, I am helping a friend finish a Series V and was interested in the
3:1 ratio. I did a rough measurement on the in vs. out and interestingly
enough, the out only comes close to equaling the inlet area, but not quite.
I am curious if cooling is an issue with these since the radiator and oil
cooler are inside the cowl.
Lowell
--------------------------------------------------
From: "Lynn Matteson" <lynnmatt(at)jps.net>
Sent: Saturday, May 28, 2011 1:33 PM
To: <kitfox-list(at)matronics.com>; <jabiruengine-list(at)matronics.com>
Subject: fun and games with a manometer
Quote: |
I built a U-tube water manometer this week, and finally got a chance to
try it out (flying) today. Prior to today, I had used it to find a slight
leak in my pitot system, which I fixed by tightening up the Nylo-Seal
fittings while watching the indicated leak disappear. Ever wonder how
much tightening is enough for those fittings? I have, and now I
know....just use a manometer on the system during the assembly of the
fittings, and you'll know when to quit tightening.
Today, I got a chance to fly briefly to test the Jabiru-dictated 2.4" of
water column difference between the inlet air ducts (each side tested
individually), and the exit-air area of the plane. I haven't had any
cooling problems, so I just wanted to test how close my installation came
to meeting that 2.4" measurement. My installation was pretty close to
right on the mark...it read about 2.3" to 2.6" depending on the bounce of
the water in the tube. Pretty happy with that, I flew home to add a 1"
lip to the bottom of my cowl exit. I bent a 20" length of sheet aluminum
to a 60� angle, letting 1" stick out into the airstream below the cowl,
and c-clamped it in place. (I didn't want to rivet it in place just to
test the theory.) I went up and flew some more...windy day, didn't want
to fly too much....and now I saw about 2.5" to 3" on either of the two
air ducts. But the really interesting thing about the last test, was that
I saw a mark on the aluminum "lip" showing where it was contacting the
left exhaust pipe. Normally, this pipe cleared the cowl/lip by about
1/2", but apparently during flight, my cowl flexes up enough to allow
contact with the exhaust pipe. No big deal you say, and I agree, but if
that lip is flexing up 1/2", what just happened to the carefully
engineered 3:1 ratio of exit air-to-inlet air that shouldn't change?
Kinda like having a wrong-way operating cowl flap for the exit air, I'm
thinking. So I need to stiffen up the lower cowl exit flange so that it
doesn't flex at all, and then do some more testing....maybe a center
support for the cowl is in order...something that will be permanently
attached to either the cowl or the airframe, but not both, so as to allow
for removing the cowl without having to deal with another fastener down
there.
If anybody's having trouble with overheating issues, yet you're sure of
the "correctness" of your installation, you might think about the
rigidity of things when air pressure gets applied.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with "Ramcharger" intake manifold...1110 hrs (since
3-27-2006)
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| - The Matronics Kitfox-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?Kitfox-List |
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Lynn Matteson
Joined: 10 Jan 2006 Posts: 2778 Location: Grass Lake, Michigan
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Posted: Sat May 28, 2011 5:16 pm Post subject: fun and games with a manometer |
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When you said "radiator" I assumed Rotax, right? I'm not sure if the
3:1 ratio still holds for a water-cooled engine...I have always held
to the 3:1 ratio for air-cooled, starting back in my radio-control
days, and when I got to the Jabiru camp (6 years ago), the first
thing I heard there was 3:1...or 4:1, or 5:1 even! I'm not sure
Jabiru knew back then, just what was required. They seem to do ok in
their own planes, but area little sketchy when it comes to advice for
homebuilts.
Probably better off looking to Rotax for an answer to that one,
Lowell, if that IS what it's powered with.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with "Ramcharger" intake manifold...1110 hrs (since
3-27-2006)
On May 28, 2011, at 8:50 PM, Lowell Fitt wrote:
Quote: |
<lcfitt(at)sbcglobal.net>
Sorry Lynn. Don't buy your experimentation. These forums are
reserved for opinions only.
Seriously, I am helping a friend finish a Series V and was
interested in the 3:1 ratio. I did a rough measurement on the in
vs. out and interestingly enough, the out only comes close to
equaling the inlet area, but not quite. I am curious if cooling is
an issue with these since the radiator and oil cooler are inside
the cowl.
Lowell
|
| - The Matronics Kitfox-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?Kitfox-List |
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_________________ Lynn
Kitfox IV-Jabiru 2200
N369LM |
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Lynn Matteson
Joined: 10 Jan 2006 Posts: 2778 Location: Grass Lake, Michigan
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Posted: Sat May 28, 2011 5:51 pm Post subject: fun and games with a manometer |
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Hi Lloyd-
The Jabiru engine has a pair of cooling ducts made of fiberglas, and
they suggest attaching the tubes (I used 1/4" OD aluminum tubing)
right to the ducts. I drilled into the duct, right between the spark
plugs, and JB Welded them in place, but any location thereabouts
should give you the same pressure, within reason. From these short
tubes, I connected to 1/4" rigid poly-something tubing (hardware
store stuff) with surgical tubing. The surgical tubing was a slightly
loose fit on the poly tubing, but would not pull off. I figured this
might leak a little bit so I rolled back the end of the surgical
tubing back over itself, and that made an almost impossible-to-remove
connection. Anyway, getting back to the run of the tubing, I ran the
poly tubing through an available hole...don't we all have one of
those in our firewall someplace?...and up and over my glare shield. I
stopped them there and made the connection to the manometer, again
with surgical tubing.
Oh, yeah, the manometer I built was similar to the one in:
http://www.iflyez.com/manometer.shtml but I made mine with an
aluminum plate instead of wood (gave me another chance to play with
the TIG), and used smaller tubing than the 3/8" suggested in that
article.
At first I used tap water and detergent and food coloring, and like
they say in the article, "you'll wait HOURS for the bubbles to
settle", so then I used distilled water, a dab of softener to break
the surface tension, and food coloring, and this time the water just
slides up and down the walls of the tubing without hesitation. These
things are so simple to make, but the trick is to print the scale to
*exactly* the dimension given...for accuracy. I converted the knots
numbers to "miles per hour" and checked my airspeed indicator after
first checking for leaks. I found that my airspeed was 2 miles under
at 60 mph, right on at 100 mph, and 1 mile over at 140 mph....close
enough for a Kitfox, in my book. : )
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with "Ramcharger" intake manifold...1110 hrs (since
3-27-2006)
On May 28, 2011, at 6:59 PM, Lloyd & Lorrie Cudnohufsky wrote:
Quote: |
<7suds(at)chartermi.net>
Lynn,
Cool stuff, (no pun intended) how did you get the tubes fastened in
the cowl
openings and did you run them into the cockpit? Look forward to
hearing more
about the experiments.
Lloyd Cudnohufsky
5 Outback 912 IVO IFA
Northern Mi.
|
| - The Matronics Kitfox-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?Kitfox-List |
|
_________________ Lynn
Kitfox IV-Jabiru 2200
N369LM |
|
Back to top |
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![](templates/Matronics/images/spacer.gif) |
VIXEN
Joined: 23 Nov 2009 Posts: 35
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Posted: Sat May 28, 2011 8:34 pm Post subject: fun and games with a manometer |
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More Manometer Stuff
Hi Guys
I use a manometer to balance the carbs on my 912. I connect each end of the U-Shaped clear tubing to each nipple on the intake manifolds where the balance tube goes. I loop the tubing around a yard stick and put a small amount of Rislone in the tube. All that is necessary to do is adjust the throttle linkage so that the Rislone level is EXACTLY the same on each side of the loop. This instrument is very accurate and very� small adjustments are all that is necessary.
Just to be sure I have recently bought a "Carbmate electronic balancer" as a check on my adjustments but the manometer is every bit as accurate!! Cost about $2 compared to $110.
Have fun
Don Hudgeon
Vixen 912UL�� IVO IFA
On Sat, May 28, 2011 at 6:48 PM, Lynn Matteson <lynnmatt(at)jps.net (lynnmatt(at)jps.net)> wrote:
[quote] --> Kitfox-List message posted by: Lynn Matteson <lynnmatt(at)jps.net (lynnmatt(at)jps.net)>
Hi Lloyd-
The Jabiru engine has a pair of cooling ducts made of fiberglas, and they suggest attaching the tubes (I used 1/4" OD aluminum tubing) right to the ducts. I drilled into the duct, right between the spark plugs, and JB Welded them in place, but any location thereabouts should give you the same pressure, within reason. From these short tubes, I connected to 1/4" rigid poly-something tubing (hardware store stuff) with surgical tubing. The surgical tubing was a slightly loose fit on the poly tubing, but would not pull off. I figured this might leak a little bit so I rolled back the end of the surgical tubing back over itself, and that made an almost impossible-to-remove connection. Anyway, getting back to the run of the tubing, I ran the poly tubing through an available hole...don't we all have one of those in our firewall someplace?...and up and over my glare shield. I stopped them there and made the connection to the manometer, again with surgical tubing.
Oh, yeah, the manometer I built was similar to the one in: � � �http://www.iflyez.com/manometer.shtml � � � but I made mine with an aluminum plate instead of wood (gave me another chance to play with the TIG), and used smaller tubing than the 3/8" suggested in that article.
At first I used tap water and detergent and food coloring, and like they say in the article, "you'll wait HOURS for the bubbles to settle", so then I used distilled water, a dab of softener to break the surface tension, and food coloring, and this time the water just slides up and down the walls of the tubing without hesitation. These things are so simple to make, but the trick is to print the scale to *exactly* the dimension given..for accuracy. I converted the knots numbers to "miles per hour" and checked my airspeed indicator after first checking for leaks. I found that my airspeed was 2 miles under at 60 mph, right on at 100 mph, and 1 mile over at 140 mph....close enough for a Kitfox, in my book. : )
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with "Ramcharger" intake manifold...1110 hrs (since 3-27-2006)
On May 28, 2011, at 6:59 PM, Lloyd & Lorrie Cudnohufsky wrote:
Quote: | --> Kitfox-List message posted by: "Lloyd & Lorrie Cudnohufsky" <7suds(at)chartermi.net (7suds(at)chartermi.net)>
Lynn,
Cool stuff, (no pun intended) how did you get the tubes fastened in the cowl
openings and did you run them into the cockpit? Look forward to hearing more
about the experiments.
Lloyd Cudnohufsky
5 Outback 912 IVO IFA
Northern Mi.
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