Today's Message Index:
----------------------
1. 05:11 AM - Re: Hard Starting tips (Catz631@aol.com)
2. 05:14 AM - Re: Problem solved. Rough (MacDonald Doug)
3. 06:02 AM - Re: Problem solved. Rough (joeing701@simnet.is)
4. 02:54 PM - Re: Kitfox-List: Re: Losing rpm on takeoff (Dave G)
5. 02:56 PM - Re: Kitfox-List: Re: Losing rpm on takeoff (Dave G)
Message 1
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| Subject: | Re: Hard Starting tips |
Thanks Rog !!! another page to put in my "tips" book. Keep them coming !!
Dick Maddux
Milton,Fl
Message 2
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| Subject: | Re: Problem solved. Rough |
Ah, Johann, the plot thickens. The air filter servicing could explain some things.
If your friend just re-oiled his K&N air filter, it is possible that he over-oiled
the filter medium thus choking off the air flow to the engine. Since the
engine uses unfiltered air for carb heat, carb heat would bypass the clogged with
oil air filter and allow his engine to run properly when selected.
I haven't seen this situation occur on a 912 but have done it myself on a 503.
Is it possible that while you've been troubleshooting this issue, the oil has
soaked in/dripped off the filter medium enough that proper air flow through the
filter has returned?
Just one more thing to think about.
Doug MacDonald
CH-701 C-GBQX
NW Ontario, Canada
> Time: 09:25:27 AM PST US
> From: =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= <joeing701@simnet.is>
> Subject: Re: RotaxEngines-List: Re: Problem solved. Rough
> running cured with carb
> heater
>
>
> Air cleaner has
> been cleaned with K&N cleaning kit according to the
> manual. The air
> Thanks again,
> Johann G.
Message 3
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| Subject: | Re: Problem solved. Rough |
Hello Doug.
Thank you for that suggestion. We have tried to disconnect the air hose from the
carbs completly with no avail. Same rough running in the mid range. If the situation
was a fuel starvation from the tanks or the fuel delivery, the problems
should also be noticed in the highest rpm when fuel is coming through the main
jet, but that is not the case. Normal running there, it is just the mid range
which has been cured with the richer/larger needle jet. As mentioned in Rogers
post regarding hard start, Rotax reccomend that you change the jetting in
the carb for colder season and then replace with the standard reccomended jetting
for the sommer time.
My friend did not use much oil on his filter, and by eliminating the filter proofs
that there is no problem with the air flow to the carbs.
Still wondering.
Johann G.
Iceland.
----- Upprunalegt skeyti -----
Fr: "MacDonald Doug" <dougsnash@yahoo.com>
Til: rotaxengines-list@matronics.com
Sent: Fimmtudagur, 2. desember, 2010 13:12:03 GMT +00:00 Monrovia
Efni: Re: RotaxEngines-List: Problem solved. Rough
Ah, Johann, the plot thickens. The air filter servicing could explain some things.
If your friend just re-oiled his K&N air filter, it is possible that he over-oiled
the filter medium thus choking off the air flow to the engine. Since the
engine uses unfiltered air for carb heat, carb heat would bypass the clogged with
oil air filter and allow his engine to run properly when selected.
I haven't seen this situation occur on a 912 but have done it myself on a 503.
Is it possible that while you've been troubleshooting this issue, the oil has
soaked in/dripped off the filter medium enough that proper air flow through the
filter has returned?
Just one more thing to think about.
Doug MacDonald
CH-701 C-GBQX
NW Ontario, Canada
> Time: 09:25:27 AM PST US
> From: =?ISO-8859-1?Q?J=F3hann_J=F3hannsson?= <joeing701@simnet.is>
> Subject: Re: RotaxEngines-List: Re: Problem solved. Rough
> running cured with carb
> heater
>
>
> Air cleaner has
> been cleaned with K&N cleaning kit according to the
> manual. The air
> Thanks again,
> Johann G.
Message 4
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| Subject: | Re: Kitfox-List: Re: Losing rpm on takeoff |
I have received enough email to establish a plan of action here. Despite
the fact that reducing pitch WILL result in an overspend situation with
my particular experimental installation, I will reduce the pitch and see
what happens during high speed taxi and then climb. Many people actually
using Warp props tell me that I achieve the results I am looking for.
I understand it is counter-intuitive, but apparently it is at least
somewhat common. I have a couple of theories, but for now I'll accept
positive results and remain in doubt about the actual reason. Over a
long work life I've had to do that on many occasions, because results
are what really matters.
Thanks to Guy, Lucien and those who contributed positive and helpful
advice off list. To those who offered unhelpful advice and lectures,
thanks for the efforts. It all reminds me of a saying a friend repeats
from time to time.
"In theory, theory and practice are the same; in practice they are quite
different!" This may be one of those cases.
Dave Goddard
KF IV 1050 / 582 / Warp
----- Original Message -----
From: b d
To: kitfox-list@matronics.com
Sent: Thursday, December 02, 2010 5:52 PM
Subject: Re: Kitfox-List: Re: Losing rpm on takeoff
Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
cavitation and with an prop in air (an airfoil), it's called a stall but
essentially the same-o same-o. We all know what is meant, we just have
to be tolerent of each others linguistics. To be technical I really
don't believe there is such a word as "un-stalling". It's either stalled
or not stalled but correct me if I'm wrong. But I do not what you mean
and what your getting at, it's like coming out of a stall condition.
Bruce
On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net>
wrote:
--> Kitfox-List message posted by: "Lowell Fitt"
<lcfitt@sbcglobal.net>
Mike,
I think you answered your own question. Just substitute stalled
prop for cavitating prop. I think the concept is the same In each case
the prop is pitched too high for conditions.
Lowell
--------------------------------------------------
From: "mikeperkins" <michael.perkins@rauland.com>
Sent: Thursday, December 02, 2010 11:41 AM
To: <kitfox-list@matronics.com>
Subject: Kitfox-List: Re: Losing rpm on takeoff
--> Kitfox-List message posted by: "mikeperkins"
<michael.perkins@rauland.com>
I have never heard a discussion involving aircraft props that
mentions cavitation, stirring air, humidity, or higher RPM during a
static run-up. If you have some references, please let me know.
A prop during a static run-up experiences a higher angle-of-attack
than a prop moving forward through air. The higher AOA produces more
drag, thus more load on the engine, and thus a lower RPM for a given
power setting, not higher RPM.
Some very high-performance aircraft with fixed-pitch props (long
time ago) produced so little prop thrust (blade lift) during a static
run-up that they had to be pushed to get them rolling - the prop was
stalled. Once rolling, the AOA would gradually decrease and thrust
(lift) would increase because the prop was un-stalling.
A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a
static run-up (temp dependent), and max RPM of 6600 while climbing at
Vx.
I would not be looking at the prop pitch for this particular
problem.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322085#322085
m/" target="_blank">www.aeroelectric.com
omebuiltHELP www.homebuilthelp.com
http:/r generous support!
ronics List Features Navigator to browse
s.com/Navigator?Kitfox-List"
target="_blank">http://www.matronics.com/Navigator?Kitfox-List
ronics.com/" target="_blank">http://forums.matronics.com
=============
Message 5
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| Subject: | Re: Kitfox-List: Re: Losing rpm on takeoff |
Yes that should be overspeed or over-rev, although either one could lead
to overspend so I guess it works.
----- Original Message -----
From: Dave G
To: rotaxengines-list@matronics.com ; kitfox-list@matronics.com
Sent: Thursday, December 02, 2010 6:51 PM
Subject: Re: Kitfox-List: Re: Losing rpm on takeoff
I have received enough email to establish a plan of action here.
Despite the fact that reducing pitch WILL result in an overspend
situation with my particular experimental installation, I will reduce
the pitch and see what happens during high speed taxi and then climb.
Many people actually using Warp props tell me that I achieve the results
I am looking for.
I understand it is counter-intuitive, but apparently it is at least
somewhat common. I have a couple of theories, but for now I'll accept
positive results and remain in doubt about the actual reason. Over a
long work life I've had to do that on many occasions, because results
are what really matters.
Thanks to Guy, Lucien and those who contributed positive and helpful
advice off list. To those who offered unhelpful advice and lectures,
thanks for the efforts. It all reminds me of a saying a friend repeats
from time to time.
"In theory, theory and practice are the same; in practice they are
quite different!" This may be one of those cases.
Dave Goddard
KF IV 1050 / 582 / Warp
----- Original Message -----
From: b d
To: kitfox-list@matronics.com
Sent: Thursday, December 02, 2010 5:52 PM
Subject: Re: Kitfox-List: Re: Losing rpm on takeoff
Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's
called cavitation and with an prop in air (an airfoil), it's called a
stall but essentially the same-o same-o. We all know what is meant, we
just have to be tolerent of each others linguistics. To be technical I
really don't believe there is such a word as "un-stalling". It's either
stalled or not stalled but correct me if I'm wrong. But I do not what
you mean and what your getting at, it's like coming out of a stall
condition.
Bruce
On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net>
wrote:
--> Kitfox-List message posted by: "Lowell Fitt"
<lcfitt@sbcglobal.net>
Mike,
I think you answered your own question. Just substitute stalled
prop for cavitating prop. I think the concept is the same In each case
the prop is pitched too high for conditions.
Lowell
--------------------------------------------------
From: "mikeperkins" <michael.perkins@rauland.com>
Sent: Thursday, December 02, 2010 11:41 AM
To: <kitfox-list@matronics.com>
Subject: Kitfox-List: Re: Losing rpm on takeoff
--> Kitfox-List message posted by: "mikeperkins"
<michael.perkins@rauland.com>
I have never heard a discussion involving aircraft props that
mentions cavitation, stirring air, humidity, or higher RPM during a
static run-up. If you have some references, please let me know.
A prop during a static run-up experiences a higher
angle-of-attack than a prop moving forward through air. The higher AOA
produces more drag, thus more load on the engine, and thus a lower RPM
for a given power setting, not higher RPM.
Some very high-performance aircraft with fixed-pitch props (long
time ago) produced so little prop thrust (blade lift) during a static
run-up that they had to be pushed to get them rolling - the prop was
stalled. Once rolling, the AOA would gradually decrease and thrust
(lift) would increase because the prop was un-stalling.
A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a
static run-up (temp dependent), and max RPM of 6600 while climbing at
Vx.
I would not be looking at the prop pitch for this particular
problem.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322085#322085
m/" target="_blank">www.aeroelectric.com
omebuiltHELP www.homebuilthelp.com
http:/r generous support!
ronics List Features Navigator to browse
s.com/Navigator?Kitfox-List"
target="_blank">http://www.matronics.com/Navigator?Kitfox-List
ronics.com/" target="_blank">http://forums.matronics.com
=============
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