Today's Message Index:
----------------------
1. 05:54 AM - Re: Re: Fuel Flow Problems, Again! (Vixen, Series-5) (Lynn Matteson)
2. 06:08 AM - Shock mounts (Heinz Lang)
3. 06:10 AM - Re: Rod end to elevator horn question. (Lynn Matteson)
4. 07:22 AM - Re: Rod end to elevator horn question. (Tom Jones)
5. 07:57 AM - Re: Re: Fuel Flow Problems, Again! (Vixen, Series-5) (Rueb, Duane)
6. 08:07 AM - Re: Fuel Flow Problems, Again! (Vixen, Series-5) (Tom Jones)
7. 08:37 AM - Re: Re: Fuel Flow Problems, Again! (Vixen, Series-5) (Bob Brennan)
8. 08:39 AM - Re: Shock mounts (jdmcbean)
9. 09:03 AM - Re: Rod end to elevator horn question. (Cwehner)
10. 11:53 AM - Re: Shock mounts (Lowell Fitt)
11. 12:10 PM - Re: Re: Fuel Flow Problems, Again! (Vixen, Series-5) (Lowell Fitt)
12. 12:13 PM - Re: Rod end to elevator horn question. (Tom Jones)
13. 12:37 PM - Re: Rod end to elevator horn question. (Guy Buchanan)
14. 04:25 PM - Re: Re: Fuel Flow Problems, Again! (Vixen, Series-5) (Lynn Matteson)
Message 1
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| Subject: | Re: Fuel Flow Problems, Again! (Vixen, Series-5) |
Beats me, Lowell, I'm no engineer (can't carry that burden), but I
think you're right. I've always thought of head pressure being like
you said, from the top of the fluid to the bottom. But what's to say
that you can't measure along the way from top to bottom to determine
a "head" pressure at any given point? Seems sensible to me, but like
I said I'm no engineer....I quit that school when the math got to
lookin' like Greek. : )
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 803.7 hrs
Countdown to 1000 hrs--197 to go
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)
On Oct 28, 2009, at 11:13 PM, Lowell Fitt wrote:
> <lcfitt@sbcglobal.net>
>
> I am a bit curious (maybe confused is a better word) here talking
> about head height to the filters. It seems to me that if there
> were nothing below the filter, this would be an accurate term.
> However, the fuel system remains closed to the level of the header
> tank where it is vented and it would seem to me that the total head
> of this system would be the height from the fuel level in the tank
> to the level of the vent in the header tank. This would be the
> same if it was six inch pipe, 3.8" tubing, no filters or valves or
> lots of stuff in line. Granted the filters and valves and bends in
> the line cause some resistance to fuel flow, but the head remains
> the same regardless of what is in the line.
>
> The weight of the fuel below the filter will suck on the fuel in
> the filter as well as the fuel in above the filter pushing it
> down. This is how siphons work.
>
> Correct me if this idea is all wet.
>
> Lowell Fitt
> Cameron Park, CA
> Second Build Model IV-1200 R-912 UL
> Prepping the right wing for covering
Message 2
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Hi Kitfox Flyers
Does anybody know a source for the 4 shock mounts for a 582?
Kitfox LLC sent me too small shock mounts (well, they have planes which
need engines with 100HP at least. Who is still flying with 582s
nowadays...) and they didn=B4t respond to my further inquiries.
Thanks for advice.
Heinz
KF 4, 582 LC
Message 3
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| Subject: | Re: Rod end to elevator horn question. |
Here I go again, laying my shade-tree engineering methods out there
for all the (Kitfox) world to see:
I looked at the specs for a clevis bolt (in the Spruce catalog....not
exactly the Bible of information, but it was all I had at the time)
and they show a minimum tensile strength of 125,000 PSI. I then
compared it to an AN bolt of the same size....125,000PSI. Figuring
that if the two were equal in strength, I substituted an AN
bolt...with a hex head....and now getting a screwdriver in there was
not an issue.
However, you could *maybe* use a right-angle screwdriver to get in
there, I'm just not recalling how much room there is to play with.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 803.7 hrs
Countdown to 1000 hrs--197 to go
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)
do not archive
On Oct 29, 2009, at 1:27 AM, Cwehner wrote:
>
> We're doing the final rigging and fastening of the elevator, push-
> rod, etc on a Kitfox IV. The manual and drawings show the rod-end
> and elevator control horn being fastened with a Clevis bolt and
> shear nut. I would like to confirm a few things:
> 1. there is NO washer used on this bolt and nut.
> 2. there is only about a single thread showing through the shear nut.
>
> With the covering and elevator "stop bar", there is no way to get
> my torque wrench on the shear nut for "proper" torquing so can
> someone give me their advise on how tight this nut should be. I've
> got a pretty good feel for 20-25 in/lbs. is that sufficient?
>
> and lastly what is the best way to get a flat head screw driver on
> the clevis bolt? doesn't seem to be a good way to get to it with
> the covering and "stop bar" in the way.
>
> Thanks for any help.
>
> --------
> Chris Wehner
> Tulsa, Oklahoma
> Kitfox IV, 912, Final push for completion!
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=269948#269948
>
>
Message 4
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| Subject: | Re: Rod end to elevator horn question. |
Chris,
The parts list in my 1994 classic 4 assembly manual Lists for "Rod end to elevator
horn":
1-AN23-15A Bolt , Skystar#91026.000
1-AN364-1032 Nut #91064.000
1-AN960-10 Washer #9147.000
Figure F-C-3 also shows the washer.
The torque specified for a 1032 shear nut is 12-15 inch pounds. I used an offset
screwdriver and a box end wrench and just snugged it up. 12 inch pounds is
only 1 foot pound you know.
There should be at least 1 thread showing past the nut. If yours does not with
the AN960-10 I would try a AN 960-10L (thin washer). Be sure you are using the
thin shear nut an not a AN 365 (thick nut)
--------
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269964#269964
Message 5
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| Subject: | Re: Fuel Flow Problems, Again! (Vixen, Series-5) |
Lowell:
Head pressure is much more valuable to the analysis of the problem then head vacuum.
There is no source of vacuum in our systems. When the fuel tank is low
and the item we are talking about (filter)is mounted high in the system there
is very little head pressure to urge the fluid to flow. When the tank is full,
approximately 4" more. And there is no vacuum on the bottom of the filter to
initiate flow. If the column of fuel in the lines is not solid, in other words
there is some air in the line below the filter, then you have the worst case
scenario for the initiation of flow through the filter, which has resistance
due to the surface tension of the fluid through the mesh holes and the debris
collected.
The fluid 'Pulling' on the outflow side of the system does not necessarily do
the trick, which is why we are talking about this. It would take a more significant
vacuum on the outside than would be caused by opening our fuel valve in
the cockpit. The system we are analyzing here is a gravity actuated system and
can be schematically represented by a fluid column of the height involved. Due
to gravity and column height head pressure is generated. With no restrictions
whatsoever it can be represented as being from the top of the fuel in the
tank to the level of the carburetor or engine pump inlet.
When the lines are of sufficient diameter capillary action can be ignored; especially
with a low viscosity fluid, such as 100LL. Car gas is slightly more viscous
due to the remaining oil in it. The theory that our systems is based on
presents fuel to the low portion of the system due to gravity enabled head, and
nothing else, and does not plan on any resistance higher than the 1/4" or 5/16"
i.d. lines. ANYTHING that presents a barrier placed in this initial path
will cause a resistance to the flow and the higher in the system that it is placed
the greater the resistance effect due to the diminishment of the head available
as you move up in the system.
Unlike with the siphon set up that works for a limited height, by the way, you
do not have the initiating vacuum to rely on to initiate flow in our systems.
When you suck on the siphon hose, you first establish a head if you want the
flow to continue after sucking.
So now we can see why it is not good to place anything that has resistance high
in the system used in our Kitfoxes. When turned on, a valve is essentially the
same as a line, so it causes no problem beyond adding two more connections.
Simply put, do not add any filters to our system higher than the ones that are
included in the design as they add resistance to flow where you really do not
want it.
I admit that I have not yet seen the finger filter at the tank outlet, but expect
to see that the mesh chosen is large enough and the area also large enough
so that they can be expected to work for long periods without cleaning, but I
now will be looking at them regularly, at least with a light and mirror.
Duane Rueb
-----Original Message-----
From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lynn Matteson
Sent: Thursday, October 29, 2009 5:49 AM
Subject: Re: Kitfox-List: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
Beats me, Lowell, I'm no engineer (can't carry that burden), but I
think you're right. I've always thought of head pressure being like
you said, from the top of the fluid to the bottom. But what's to say
that you can't measure along the way from top to bottom to determine
a "head" pressure at any given point? Seems sensible to me, but like
I said I'm no engineer....I quit that school when the math got to
lookin' like Greek. : )
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 803.7 hrs
Countdown to 1000 hrs--197 to go
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)
On Oct 28, 2009, at 11:13 PM, Lowell Fitt wrote:
> <lcfitt@sbcglobal.net>
>
> I am a bit curious (maybe confused is a better word) here talking
> about head height to the filters. It seems to me that if there
> were nothing below the filter, this would be an accurate term.
> However, the fuel system remains closed to the level of the header
> tank where it is vented and it would seem to me that the total head
> of this system would be the height from the fuel level in the tank
> to the level of the vent in the header tank. This would be the
> same if it was six inch pipe, 3.8" tubing, no filters or valves or
> lots of stuff in line. Granted the filters and valves and bends in
> the line cause some resistance to fuel flow, but the head remains
> the same regardless of what is in the line.
>
> The weight of the fuel below the filter will suck on the fuel in
> the filter as well as the fuel in above the filter pushing it
> down. This is how siphons work.
>
> Correct me if this idea is all wet.
>
> Lowell Fitt
> Cameron Park, CA
> Second Build Model IV-1200 R-912 UL
> Prepping the right wing for covering
Message 6
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| Subject: | Re: Fuel Flow Problems, Again! (Vixen, Series-5) |
I think the head pressure is the same as long as the fuel is flowing. If it stops
for some reason...unporting a tank...a filter high on the line close to the
tank may make getting the flow started again a problem.
--------
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269972#269972
Message 7
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| Subject: | Re: Fuel Flow Problems, Again! (Vixen, Series-5) |
Good explanation Duane, but there is one term that keeps coming up in this
thread that I can't say I understand completely - many talk about their wing
tank becoming "unported" in flight, which I understand as no-more-flow, but
what can cause this "unporting" and is it unrecoverable in flight?
I have a KF2 with the main tank in my lap and a reserve tank in the wing - I
know that getting the fuel to flow from the reserve on the ground doesn't
always work but in the air the fuel cap has a tube facing into the airflow
which provides enough pressure to push any fuel out of that tank easily. I
don't understand why later systems with header tanks have this "unported"
problem.
Thanks in advance for any explanations...
Bob Brennan - N717GB
ELSA Repairman, inspection rated
1991 UK Model 2 ELSA Kitfox taildragger
Rotax 582 with 3 blade GSC prop
Wrightsville Pa
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Rueb, Duane
Sent: Thursday, October 29, 2009 10:54 AM
Subject: RE: Kitfox-List: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
Lowell:
Head pressure is much more valuable to the analysis of the problem
then head vacuum. There is no source of vacuum in our systems. When the
fuel tank is low and the item we are talking about (filter)is mounted high
in the system there is very little head pressure to urge the fluid to flow.
When the tank is full, approximately 4" more. And there is no vacuum on the
bottom of the filter to initiate flow. If the column of fuel in the lines
is not solid, in other words there is some air in the line below the filter,
then you have the worst case scenario for the initiation of flow through the
filter, which has resistance due to the surface tension of the fluid through
the mesh holes and the debris collected.
The fluid 'Pulling' on the outflow side of the system does not
necessarily do the trick, which is why we are talking about this. It would
take a more significant vacuum on the outside than would be caused by
opening our fuel valve in the cockpit. The system we are analyzing here is a
gravity actuated system and can be schematically represented by a fluid
column of the height involved. Due to gravity and column height head
pressure is generated. With no restrictions whatsoever it can be
represented as being from the top of the fuel in the tank to the level of
the carburetor or engine pump inlet.
When the lines are of sufficient diameter capillary action can be
ignored; especially with a low viscosity fluid, such as 100LL. Car gas is
slightly more viscous due to the remaining oil in it. The theory that our
systems is based on presents fuel to the low portion of the system due to
gravity enabled head, and nothing else, and does not plan on any resistance
higher than the 1/4" or 5/16" i.d. lines. ANYTHING that presents a barrier
placed in this initial path will cause a resistance to the flow and the
higher in the system that it is placed the greater the resistance effect due
to the diminishment of the head available as you move up in the system.
Unlike with the siphon set up that works for a limited height, by
the way, you do not have the initiating vacuum to rely on to initiate flow
in our systems. When you suck on the siphon hose, you first establish a
head if you want the flow to continue after sucking.
So now we can see why it is not good to place anything that has resistance
high in the system used in our Kitfoxes. When turned on, a valve is
essentially the same as a line, so it causes no problem beyond adding two
more connections.
Simply put, do not add any filters to our system higher than the
ones that are included in the design as they add resistance to flow where
you really do not want it.
I admit that I have not yet seen the finger filter at the tank
outlet, but expect to see that the mesh chosen is large enough and the area
also large enough so that they can be expected to work for long periods
without cleaning, but I now will be looking at them regularly, at least with
a light and mirror.
Duane Rueb
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lynn Matteson
Sent: Thursday, October 29, 2009 5:49 AM
Subject: Re: Kitfox-List: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
Beats me, Lowell, I'm no engineer (can't carry that burden), but I
think you're right. I've always thought of head pressure being like
you said, from the top of the fluid to the bottom. But what's to say
that you can't measure along the way from top to bottom to determine
a "head" pressure at any given point? Seems sensible to me, but like
I said I'm no engineer....I quit that school when the math got to
lookin' like Greek. : )
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 803.7 hrs
Countdown to 1000 hrs--197 to go
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)
On Oct 28, 2009, at 11:13 PM, Lowell Fitt wrote:
> <lcfitt@sbcglobal.net>
>
> I am a bit curious (maybe confused is a better word) here talking
> about head height to the filters. It seems to me that if there
> were nothing below the filter, this would be an accurate term.
> However, the fuel system remains closed to the level of the header
> tank where it is vented and it would seem to me that the total head
> of this system would be the height from the fuel level in the tank
> to the level of the vent in the header tank. This would be the
> same if it was six inch pipe, 3.8" tubing, no filters or valves or
> lots of stuff in line. Granted the filters and valves and bends in
> the line cause some resistance to fuel flow, but the head remains
> the same regardless of what is in the line.
>
> The weight of the fuel below the filter will suck on the fuel in
> the filter as well as the fuel in above the filter pushing it
> down. This is how siphons work.
>
> Correct me if this idea is all wet.
>
> Lowell Fitt
> Cameron Park, CA
> Second Build Model IV-1200 R-912 UL
> Prepping the right wing for covering
Message 8
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Heinz,
Sorry.. didn't see any further inquiries. We have since found other
mounts via another source that matches closer to your photos.
Fly Safe !!
John & Debra McBean
Ph 208.337.5111
www.kitfoxaircraft.com
"The Sky is not the Limit... It's a Playground"
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Heinz Lang
Sent: Thursday, October 29, 2009 7:04 AM
Subject: Kitfox-List: Shock mounts
Hi Kitfox Flyers
Does anybody know a source for the 4 shock mounts for a 582?
Kitfox LLC sent me too small shock mounts (well, they have planes which need
engines with 100HP at least. Who is still flying with 582s
nowadays...) and they didnt respond to my further inquiries.
Thanks for advice.
Heinz
KF 4, 582 LC
Message 9
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| Subject: | Re: Rod end to elevator horn question. |
Thanks Lynn and Tom.
Thats interesting Tom because my '91 model IV manual doesn't show the washer in
the Drawing F-C-3 nor does it mention using one in the worded instructions.
Using the AN23-15A bolt with no washer I only have 1 thread showing past the shear
nut, even a thin washer wouldn't work. I may try using 1 size longer bolt
so I can use a washer and have a few threads sticking out. I Would feel much
better about that. I am guessing the only concern is how much and hard it rubs
against the fabric when full aft.
--------
Chris Wehner
Tulsa, Oklahoma
Kitfox IV, 912, Final push for completion!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269982#269982
Message 10
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| Subject: | Re: Shock mounts |
Heinz,
I have four mounts from a 1992 vintage project that will have a 912
install. They are NOS - old car talk meaning New Old Stock.
Contact me at lcfitt@sbcglobal.net if you are interested.
Lowell
----- Original Message -----
From: "Heinz Lang" <hlang@bluewin.ch>
Sent: Thursday, October 29, 2009 6:03 AM
Subject: Kitfox-List: Shock mounts
Hi Kitfox Flyers
Does anybody know a source for the 4 shock mounts for a 582?
Kitfox LLC sent me too small shock mounts (well, they have planes which
need engines with 100HP at least. Who is still flying with 582s
nowadays...) and they didnt respond to my further inquiries.
Thanks for advice.
Heinz
KF 4, 582 LC
Message 11
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| Subject: | Re: Fuel Flow Problems, Again! (Vixen, Series-5) |
Bob and all,
I guess what precipitated my original post and what may answer Bob's
question is the configuration I had in my original build Model IV. It had
the glass Purelator filters just below the tanks and and a tad behind the
doors. There were no valves so I carried some light plastic clamps so I
could clamp off the lines if I needed to for any reason.
In 900 hours of flight, I had no problems what-so-ever. The lines were
5/16" id and as Don Smythe suggested, I was very careful of the run of the
lines to the header tank.
As many have reported, I did have uneven fuel flow on long flights, but
became convinced that it was because of the tendency of all. and I repeat
all, Kitfox pilots to fly in a slightly uncoordinated manner with one wing
low on the more boring portions of the three and four hour flights.
I did intentionally umport my tanks once on a long decent from the ridges of
the Sierras to home as I was on the bottom fourth of the tank capacity and
with the early aft positioned pick-up on the wing tanks, they rose above the
level of the fuel in the tanks. I watched this unfold through the
transparent vent line and the Purelator filters. Once the low fuel
indicator began to flash, I raised the nose to level flight and fuel began
to flow gain, the lights went out and I proceeded home. I landed with six
gallons in each tank.
One more thought, my wife tells me we need more fuel for the lawnmower - Yes
she allows me to allow her to undertake that task routinely. I plan on
buying five gallons. Then as is the practice, I will transfer half to
another tank so she will not have to tote the full five to the lawnmower. I
plan on siphoning the gas this time to do a little bit of Don Smything
(sorry Don) and with a Purelator filter in the line, I plan doing it two
stages, one with the filter in the upward portion of the line - negative
head, and one with the filter in the downword portion and see if I can tell
a difference in the fuel flow. Any takers on what the results might be.
Lowell
----- Original Message -----
From: "Bob Brennan" <matronics@bob.brennan.name>
Sent: Thursday, October 29, 2009 8:24 AM
Subject: RE: Kitfox-List: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
> <matronics@bob.brennan.name>
>
> Good explanation Duane, but there is one term that keeps coming up in this
> thread that I can't say I understand completely - many talk about their
> wing
> tank becoming "unported" in flight, which I understand as no-more-flow,
> but
> what can cause this "unporting" and is it unrecoverable in flight?
>
> I have a KF2 with the main tank in my lap and a reserve tank in the wing -
> I
> know that getting the fuel to flow from the reserve on the ground doesn't
> always work but in the air the fuel cap has a tube facing into the airflow
> which provides enough pressure to push any fuel out of that tank easily. I
> don't understand why later systems with header tanks have this "unported"
> problem.
>
> Thanks in advance for any explanations...
>
> Bob Brennan - N717GB
> ELSA Repairman, inspection rated
> 1991 UK Model 2 ELSA Kitfox taildragger
> Rotax 582 with 3 blade GSC prop
> Wrightsville Pa
>
> -----Original Message-----
> From: owner-kitfox-list-server@matronics.com
> [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Rueb, Duane
> Sent: Thursday, October 29, 2009 10:54 AM
> To: 'kitfox-list@matronics.com'
> Subject: RE: Kitfox-List: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
>
>
> Lowell:
>
> Head pressure is much more valuable to the analysis of the problem
> then head vacuum. There is no source of vacuum in our systems. When the
> fuel tank is low and the item we are talking about (filter)is mounted high
> in the system there is very little head pressure to urge the fluid to
> flow.
> When the tank is full, approximately 4" more. And there is no vacuum on
> the
> bottom of the filter to initiate flow. If the column of fuel in the
> lines
> is not solid, in other words there is some air in the line below the
> filter,
> then you have the worst case scenario for the initiation of flow through
> the
> filter, which has resistance due to the surface tension of the fluid
> through
> the mesh holes and the debris collected.
> The fluid 'Pulling' on the outflow side of the system does not
> necessarily do the trick, which is why we are talking about this. It would
> take a more significant vacuum on the outside than would be caused by
> opening our fuel valve in the cockpit. The system we are analyzing here is
> a
> gravity actuated system and can be schematically represented by a fluid
> column of the height involved. Due to gravity and column height head
> pressure is generated. With no restrictions whatsoever it can be
> represented as being from the top of the fuel in the tank to the level of
> the carburetor or engine pump inlet.
> When the lines are of sufficient diameter capillary action can be
> ignored; especially with a low viscosity fluid, such as 100LL. Car gas is
> slightly more viscous due to the remaining oil in it. The theory that our
> systems is based on presents fuel to the low portion of the system due to
> gravity enabled head, and nothing else, and does not plan on any
> resistance
> higher than the 1/4" or 5/16" i.d. lines. ANYTHING that presents a
> barrier
> placed in this initial path will cause a resistance to the flow and the
> higher in the system that it is placed the greater the resistance effect
> due
> to the diminishment of the head available as you move up in the system.
> Unlike with the siphon set up that works for a limited height, by
> the way, you do not have the initiating vacuum to rely on to initiate flow
> in our systems. When you suck on the siphon hose, you first establish a
> head if you want the flow to continue after sucking.
> So now we can see why it is not good to place anything that has resistance
> high in the system used in our Kitfoxes. When turned on, a valve is
> essentially the same as a line, so it causes no problem beyond adding two
> more connections.
> Simply put, do not add any filters to our system higher than the
> ones that are included in the design as they add resistance to flow where
> you really do not want it.
> I admit that I have not yet seen the finger filter at the tank
> outlet, but expect to see that the mesh chosen is large enough and the
> area
> also large enough so that they can be expected to work for long periods
> without cleaning, but I now will be looking at them regularly, at least
> with
> a light and mirror.
>
> Duane Rueb
>
>
> -----Original Message-----
> From: owner-kitfox-list-server@matronics.com
> [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lynn Matteson
> Sent: Thursday, October 29, 2009 5:49 AM
> To: kitfox-list@matronics.com
> Subject: Re: Kitfox-List: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
>
>
> Beats me, Lowell, I'm no engineer (can't carry that burden), but I
> think you're right. I've always thought of head pressure being like
> you said, from the top of the fluid to the bottom. But what's to say
> that you can't measure along the way from top to bottom to determine
> a "head" pressure at any given point? Seems sensible to me, but like
> I said I'm no engineer....I quit that school when the math got to
> lookin' like Greek. : )
>
> Lynn Matteson
> Kitfox IV Speedster, taildragger
> Jabiru 2200, #2062, 803.7 hrs
> Countdown to 1000 hrs--197 to go
> Sensenich 62"x46" Wood prop
> Electroair direct-fire ignition system
> Rotec TBI-40 injection
> Status: flying (and learning)
>
>
> On Oct 28, 2009, at 11:13 PM, Lowell Fitt wrote:
>
>> <lcfitt@sbcglobal.net>
>>
>> I am a bit curious (maybe confused is a better word) here talking
>> about head height to the filters. It seems to me that if there
>> were nothing below the filter, this would be an accurate term.
>> However, the fuel system remains closed to the level of the header
>> tank where it is vented and it would seem to me that the total head
>> of this system would be the height from the fuel level in the tank
>> to the level of the vent in the header tank. This would be the
>> same if it was six inch pipe, 3.8" tubing, no filters or valves or
>> lots of stuff in line. Granted the filters and valves and bends in
>> the line cause some resistance to fuel flow, but the head remains
>> the same regardless of what is in the line.
>>
>> The weight of the fuel below the filter will suck on the fuel in
>> the filter as well as the fuel in above the filter pushing it
>> down. This is how siphons work.
>>
>> Correct me if this idea is all wet.
>>
>> Lowell Fitt
>> Cameron Park, CA
>> Second Build Model IV-1200 R-912 UL
>> Prepping the right wing for covering
>
>
>
Message 12
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| Subject: | Re: Rod end to elevator horn question. |
> Thanks Lynn and Tom.
> Thats interesting Tom because my '91 model IV manual doesn't show the washer
in the Drawing F-C-3 nor does it mention using one in the worded instructions.
Using the AN23-15A bolt with no washer I only have 1 thread showing past the
shear nut, even a thin washer wouldn't work. I may try using 1 size longer bolt
so I can use a washer and have a few threads sticking out. I Would feel much
better about that. I am guessing the only concern is how much and hard it rubs
against the fabric when full aft.
Chris, I was at the airport this AM so checked that. Mine has 3 threads showing
past a thick washer. I wonder if you have the correct length clevis bolt.
You didn't mix it up with one of the AN23-14A that go in the elevator idler bell
crank by chance? You definitely should get one that has at least one thread
showing past the washer.
I have a 94 manual and an updated May 96 version too. Both show the washer in
the drawing and the 94 lists it in the parts list. Neither mention the washer
in the final assembly section though.
The head of the clevis bolt goes on the right side. Mine just touches the fabric
at full up elevator. There is plenty room for the bolt end to stick out on
the left side without any interference.
--------
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270004#270004
Message 13
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| Subject: | Re: Rod end to elevator horn question. |
At 10:27 PM 10/28/2009, you wrote:
> 1. there is NO washer used on this bolt and nut.
> 2. there is only about a single thread showing through the shear nut.
Sounds good to me, except I used a MS21042 nut since it locks. All
you're trying to do is come up with a set-up that doesn't touch the
fabric when full up elevator.
>With the covering and elevator "stop bar", there is no way to get my
>torque wrench on the shear nut for "proper" torquing so can someone
>give me their advise on how tight this nut should be. I've got a
>pretty good feel for 20-25 in/lbs. is that sufficient?
Yep.
>and lastly what is the best way to get a flat head screw driver on
>the clevis bolt? doesn't seem to be a good way to get to it with the
>covering and "stop bar" in the way.
I used a small screwdriver sideways to hold the flat head. (Use the
edge of the blade rather than the tip.) I tightened the nut with a box wrench.
Guy Buchanan
San Diego, CA
K-IV 1200 / 582-C / Warp / 400 hrs. and counting
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| Subject: | Re: Fuel Flow Problems, Again! (Vixen, Series-5) |
The following refers to the Kitfox IV that I built, and may not be
the same on a KF2.
The unporting refers to not having any fuel AT the fuel tank outlet.
What causes it is having low fuel, and maybe pointing the plane down,
as in a descent to land. Under this condition, or any condition where
the fuel runs away from the fuel tank outlet, the tank is said to be
"unported." Is it *recoverable* in flight? Yes, IF you bring the nose
of the aircraft up to level (if the tank is only *moderately* low of
fuel), or above level (if the tank is *fairly* low on fuel.) The
terms moderately and fairly are what you have to decide for yourself.
The main thing is to get the nose up so what fuel is left runs back
to the outlet port and starts to flow downward. Something that I
noticed with my Jabiru-powered plane is that the header tank is at
about the same elevation in level flight as the fuel metering device.
If I let the header tank get below a certain level in fuel capacity
(because I'm descending with low fuel in the wing tanks, and they
have unported), and then point the plane up so as to let the
remaining fuel in the wing tanks rush back towards the ports, I may
have just put my header tanks' supply of fuel below the point where
the fuel will (gravity) flow into the fuel metering device. I don't
care to have to practice this, but I'm thinking that by porpoising
the plane *just* the right amount, that I can cause the header tank
to refill...plane pointing up....and then level off to let that fuel
(gravity) flow to the engine. When I recently had an occasion/need to
do this, a field came into view before I could do any more than about
one "up-then-level" cycle, and I *decided* to land instead of pushing
my luck on my untested theory. : )
Another way to unport the tank is to be banking with a low fuel
supply. A bank to the left with low fuel (a subjective term) on board
will/may unport the left wing tank, while the right wing tank
supplies ALL the fuel that the engine requires. If you bank long
enough, the right tank becomes empty...for example...and the low fuel
light comes on, so you level the plane, or even go to a right bank,
hoping the left tank will hurry up and fill the header tank and you
can continue on to a refueling station. If the left tank allows the
fuel to flow quickly enough, the engine catches, and you can fly
towards the nearest J.C. Penney for some new skivvies....and ya might
just wanna get some fuel while you're at it.
That's unporting from a practitioners (been there, done that) point
of view. It's not the header tank that becomes
unported....USUALLY....it's the fuel tanks. Your situation, Bob,
would require you to study the flow of the fuel and see what you
should do if you too, have a brain fart and need to rely on some
aerial gymnastics.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 804.3 hrs
Countdown to 1000 hrs--196 to go
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)
On Oct 29, 2009, at 11:24 AM, Bob Brennan wrote:
> <matronics@bob.brennan.name>
>
> what can cause this "unporting" and is it unrecoverable in flight?
>
> I have a KF2 with the main tank in my lap and a reserve tank in the
> wing - I
> know that getting the fuel to flow from the reserve on the ground
> doesn't
> always work but in the air the fuel cap has a tube facing into the
> airflow
> which provides enough pressure to push any fuel out of that tank
> easily. I
> don't understand why later systems with header tanks have this
> "unported"
> problem.
>
> Thanks in advance for any explanations...
>
> Bob Brennan - N717GB
> ELSA Repairman, inspection rated
> 1991 UK Model 2 ELSA Kitfox taildragger
> Rotax 582 with 3 blade GSC prop
> Wrightsville Pa
>
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