Today's Message Index:
----------------------
1. 03:19 AM - Re: fun and games with a manometer (Lynn Matteson)
2. 08:52 AM - Re: fun and games with a manometer (zeprep251@aol.com)
3. 11:33 AM - Re: fun and games with a manometer (Lynn Matteson)
4. 12:11 PM - fun and games with a manometer (BobsV35B@aol.com)
Message 1
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| Subject: | Re: fun and games with a manometer |
Absolutely, positively, pretty damn certain that isn't happening, G.
This is a 4-cylinder Jabiru after all, and it doesn't move hardly at
all, let alone 1/2"+ of movement. The cowl flex is the culprit. This
cowl is a Skyfox cowl, and is unsupported across the whole bottom of
the exit-air opening. It has a built-in lip of about 1", but it's
only at about a 15-degree angle to the rest of the cowl, so it
doesn't offer a lot in the way of stiffening.
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 29, 2011, at 12:24 AM, zeprep251@aol.com wrote:
> Lynn,
> Are you certain that the engine torque at max throttle does not
> rotate the engine in it's mounts far enough to cause contact with
> the cowl?
> G.Aman
>
Message 2
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| Subject: | Re: fun and games with a manometer |
Lynn,
Just a thought.My 2200 is a pusher and I have to rotate the mounts in their
sockets every couple years because they take a set that can be seen easily
,especially the fronts.It drops the engine almost 1/4 "Do you have dyna-foc
al mounts in the Kit-Fox? .
G.Aman
-----Original Message-----
From: Lynn Matteson <lynnmatt@jps.net>
Sent: Sun, May 29, 2011 3:19 am
Subject: Re: JabiruEngine-List: fun and games with a manometer
Absolutely, positively, pretty damn certain that isn't happening, G.
This is a 4-cylinder Jabiru after all, and it doesn't move hardly at
all, let alone 1/2"+ of movement. The cowl flex is the culprit. This
cowl is a Skyfox cowl, and is unsupported across the whole bottom of
the exit-air opening. It has a built-in lip of about 1", but it's
only at about a 15-degree angle to the rest of the cowl, so it
doesn't offer a lot in the way of stiffening.
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 29, 2011, at 12:24 AM, zeprep251@aol.com wrote:
> Lynn,
> Are you certain that the engine torque at max throttle does not
> rotate the engine in it's mounts far enough to cause contact with
> the cowl?
> G.Aman
>
Message 3
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| Subject: | Re: fun and games with a manometer |
They are not dyna-focal, but almost...the mounting bolts point
straight ahead, so the rubbers sit vertically, and the holes through
them, horizontally. I changed rubbers for the very reason you
described....sag. The rubbers I got from USJabiru are soft, while
ones I got from Sonex (and subsequently removed right after
installation) are hard as a rock, and transmit vibrations. I went
back to the Jabiru-supplied rubbers after feeling vibrations from the
others. Last June I had the engine out for work, and the new
rubbers...then a year old, and now two years old, are still without
the tell-tale signs of needing to be rotated or replaced. The first
set I used for 3 years and they were distorted when I finally
scrapped them.
I made a brace today to keep the lower edge of the cowl from blowing
upward and diminishing the exit-air area. It works well, but didn't
make a lot of difference in the readings I was getting with the
manometer. The 2.45-3.0" figure still stands....hard to nail the
figure down because of the bounce of the liquid in the manometer. But
the numbers are bearing out the validity of doing this test, coupled
with the very good CHT temperatures....287-304 degrees F. during
today's flight, and that's pretty typical. OAT today is 79 F.
Looking back at the temporary lip that I made....1" deep, 20" long,
and at a 60-degree angle to the wind...might have been what caused
the cowl to deform and touch the exhaust pipe. After all, that's a
pretty good "airbrake" sticking down into the airstream, and being
mounted to a flexible cowl, it would want to take the easy route and
deflect upwards to avoid the wind.
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 29, 2011, at 11:49 AM, zeprep251@aol.com wrote:
> Lynn,
> Just a thought.My 2200 is a pusher and I have to rotate the mounts
> in their sockets every couple years because they take a set that
> can be seen easily,especially the fronts.It drops the engine almost
> 1/4 "Do you have dyna-focal mounts in the Kit-Fox? .
>
> G.Aman
>
Message 4
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| Subject: | fun and games with a manometer |
Good Afternoon Lynn,
You mentioned that you used a sixty degree lip. Seems to me I once read
that anything beyond thirty degrees of "lip" actually decreases the airflow.
It causes too much turbulence in the area. No knowledge from me. just a
memory from a long time ago.
Happy Skies,
Old Bob
Do Not Archive
In a message dated 5/29/2011 1:33:13 P.M. Central Daylight Time,
lynnmatt@jps.net writes:
--> JabiruEngine-List message posted by: Lynn Matteson <lynnmatt@jps.net>
They are not dyna-focal, but almost...the mounting bolts point
straight ahead, so the rubbers sit vertically, and the holes through
them, horizontally. I changed rubbers for the very reason you
described....sag. The rubbers I got from USJabiru are soft, while
ones I got from Sonex (and subsequently removed right after
installation) are hard as a rock, and transmit vibrations. I went
back to the Jabiru-supplied rubbers after feeling vibrations from the
others. Last June I had the engine out for work, and the new
rubbers...then a year old, and now two years old, are still without
the tell-tale signs of needing to be rotated or replaced. The first
set I used for 3 years and they were distorted when I finally
scrapped them.
I made a brace today to keep the lower edge of the cowl from blowing
upward and diminishing the exit-air area. It works well, but didn't
make a lot of difference in the readings I was getting with the
manometer. The 2.45-3.0" figure still stands....hard to nail the
figure down because of the bounce of the liquid in the manometer. But
the numbers are bearing out the validity of doing this test, coupled
with the very good CHT temperatures....287-304 degrees F. during
today's flight, and that's pretty typical. OAT today is 79 F.
Looking back at the temporary lip that I made....1" deep, 20" long,
and at a 60-degree angle to the wind...might have been what caused
the cowl to deform and touch the exhaust pipe. After all, that's a
pretty good "airbrake" sticking down into the airstream, and being
mounted to a flexible cowl, it would want to take the easy route and
deflect upwards to avoid the wind.
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 29, 2011, at 11:49 AM, zeprep251@aol.com wrote:
> Lynn,
> Just a thought.My 2200 is a pusher and I have to rotate the mounts
> in their sockets every couple years because they take a set that
> can be seen easily,especially the fronts.It drops the engine almost
> 1/4 "Do you have dyna-focal mounts in the Kit-Fox? .
>
> G.Aman
>
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