Today's Message Index:
----------------------
1. 06:09 AM - Re: Push pull tube bushing (Tom Jones)
2. 06:23 AM - Re: Push pull tube bushing (Lowell Fitt)
3. 06:37 AM - Re: Push pull tube bushing (jareds)
4. 08:20 AM - Re: Re: Push pull tube bushing (Lowell Fitt)
5. 11:42 AM - (malpass-architect)
6. 02:43 PM - Yahoo news article - The Great Ethanol Scam (Rexinator)
7. 04:14 PM - Re: Push pull tube bushing (Tom Jones)
8. 05:27 PM - Charging System Theory - A few Questions (darinh)
9. 05:48 PM - Re: Re: Push pull tube bushing (Lowell Fitt)
10. 06:55 PM - Re: Charging System Theory - A few Questions (kerrjohna@comcast.net)
11. 07:36 PM - Re: Charging System Theory - A few Questions (KITFOXZ@aol.com)
12. 08:14 PM - Re: Charging System Theory - A few Questions (Noel)
13. 08:21 PM - Re: Charging System Theory - A few Questions (Noel)
14. 08:26 PM - Re: Charging System Theory - A few Questions (Noel)
15. 09:14 PM - Re: Charging System Theory - A few Questions (darinh)
16. 09:17 PM - Re: Charging System Theory - A few Questions (darinh)
17. 10:15 PM - Re: Charging System Theory - A few Questions (darinh)
Message 1
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| Subject: | Re: Push pull tube bushing |
jareds(at)verizon.net wrote:
> Doin the annual on kf model IV and noticed the bushing on the push pull
> tube has popped out of the steel ring in the center of the aft portion
> of plane.
> I know it is only there as a guide but have no idea how one would change
> it out or if you can even get one from KF?
> I've always lubed with silicone and am wondering if greasing the outer
> ring that the tube slides in will suffice?
> Suggestions?
The elevator push pull tube bushing needs to be secure in the steel ring. The
purpose is to keep the tube straight during up elevator pressure.
Do you have an inspection ring installed in belly fabric just forward of the front
end of the large tube? That inspection ring was installed so that the tube
and bushing can be removed from the fuselage. The installation procedure is
to secure the bushing in the steel ring with structural adhesive and then safety
wire through a hole you drill in the lip of the bushing.
If there is no inspection ring there you can install one now. I have the instructions
in my notes. An inspection ring in the belly just forward or aft of the
bushing makes maintenance much easier. I put both in after I about went nuts
trying to grease the bushing doing my first annual.
There used to be a two piece nylon bushing available. Kitfox LLC may still have
them.
I use white lithium grease on mine. Smooth as silk.
--------
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=244253#244253
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| Subject: | Re: Push pull tube bushing |
Can youi retrieve it and reinsert it in the ring. As I recall, this
happened to me. Having a lathe, I made a new bushing with a groove in it
and then slit it with an angled cut, placed it over the tube and into the
ring and then put a snap ring to keep it in place. With the new build, that
is how I am doing it now.
Lowell
----- Original Message -----
From: "jareds" <jareds@verizon.net>
Sent: Friday, May 15, 2009 8:35 PM
Subject: Kitfox-List: Push pull tube bushing
>
> Doin the annual on kf model IV and noticed the bushing on the push pull
> tube has popped out of the steel ring in the center of the aft portion of
> plane.
> I know it is only there as a guide but have no idea how one would change
> it out or if you can even get one from KF?
> I've always lubed with silicone and am wondering if greasing the outer
> ring that the tube slides in will suffice?
> Suggestions?
>
>
>
Message 3
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| Subject: | Re: Push pull tube bushing |
I can retrieve it or at least part of it and prob glue it back in place
for now but having another in hand for later would be nice.
I'm betting that the front portion of this plastic bushing had a lip on
it and it is now gone. But hopefully a little glue will hold it. I
always used litheum grease on it but can't remember if i have an
inspection door under there or not. I will certainly put one in if i dont.
Any chance you have a tail spring laying around for the KF IV
Lowell Fitt wrote:
>
> Can youi retrieve it and reinsert it in the ring. As I recall, this
> happened to me. Having a lathe, I made a new bushing with a groove in
> it and then slit it with an angled cut, placed it over the tube and
> into the ring and then put a snap ring to keep it in place. With the
> new build, that is how I am doing it now.
>
> Lowell
>
> ----- Original Message ----- From: "jareds" <jareds@verizon.net>
> To: <kitfox-list@matronics.com>; "Warren Vander Wal" <wandbvw@bektel.com>
> Sent: Friday, May 15, 2009 8:35 PM
> Subject: Kitfox-List: Push pull tube bushing
>
>
>>
>> Doin the annual on kf model IV and noticed the bushing on the push
>> pull tube has popped out of the steel ring in the center of the aft
>> portion of plane.
>> I know it is only there as a guide but have no idea how one would
>> change it out or if you can even get one from KF?
>> I've always lubed with silicone and am wondering if greasing the
>> outer ring that the tube slides in will suffice?
>> Suggestions?
>>
>>
>>
>>
>>
>
>
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| Subject: | Re: Push pull tube bushing |
Tom,
I find this description interesting. If you glue the bushing in with
structural adhesive, and assuming this stuff sticks, the inspection ring
will be pretty much a cosmetic featrure as the rivets holding the rod end
stud will prevent the push/pull tube from sliding past the bushing. Also if
the bushing is installed with the lip aft, it will not be removable. I
dealt with this years ago and after the ring slipped out, I replaced it with
a split one and the old one just rode along as a light weight passenger
after that.
The real key is a two piece or split ring held in place with a snap ring.
Lowell
----- Original Message -----
From: "Tom Jones" <nahsikhs@elltel.net>
Sent: Saturday, May 16, 2009 6:08 AM
Subject: Kitfox-List: Re: Push pull tube bushing
>
>
> jareds(at)verizon.net wrote:
>> Doin the annual on kf model IV and noticed the bushing on the push pull
>> tube has popped out of the steel ring in the center of the aft portion
>> of plane.
>> I know it is only there as a guide but have no idea how one would change
>> it out or if you can even get one from KF?
>> I've always lubed with silicone and am wondering if greasing the outer
>> ring that the tube slides in will suffice?
>> Suggestions?
>
>
> The elevator push pull tube bushing needs to be secure in the steel ring.
> The purpose is to keep the tube straight during up elevator pressure.
>
> Do you have an inspection ring installed in belly fabric just forward of
> the front end of the large tube? That inspection ring was installed so
> that the tube and bushing can be removed from the fuselage. The
> installation procedure is to secure the bushing in the steel ring with
> structural adhesive and then safety wire through a hole you drill in the
> lip of the bushing.
>
> If there is no inspection ring there you can install one now. I have the
> instructions in my notes. An inspection ring in the belly just forward or
> aft of the bushing makes maintenance much easier. I put both in after I
> about went nuts trying to grease the bushing doing my first annual.
>
> There used to be a two piece nylon bushing available. Kitfox LLC may
> still have them.
>
> I use white lithium grease on mine. Smooth as silk.
>
> --------
> 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=244253#244253
>
>
>
Message 5
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Did any of you kitfoxers go to the world famous Joe Nall fly-in in South
Carolina this past week?
It is a R/C sight to behold.............................................
Bill Malpass
Kitfox III Taildragger (obviously) 582 Gray head - Ivo Prop
300 hrs SMOH
Message 6
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| Subject: | Yahoo news article - The Great Ethanol Scam |
Not that I'm trying to create any debate (certainly here we all agree ethanol is
bad). This just neatly explains the issue.
The Great Ethanol Scam
http://news.yahoo.com/s/bw/20090515/bs_bw/may2009bw20090514058678
Rex Hefferan
M2/582 Colorado
Message 7
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| Subject: | Re: Push pull tube bushing |
lcfitt(at)sbcglobal.net wrote:
> Tom,
>
> I find this description interesting. If you glue the bushing in with
> structural adhesive, and assuming this stuff sticks, the inspection ring
> will be pretty much a cosmetic featrure as the rivets holding the rod end
> stud will prevent the push/pull tube from sliding past the bushing. Also if
> the bushing is installed with the lip aft, it will not be removable. I
> dealt with this years ago and after the ring slipped out, I replaced it with
> a split one and the old one just rode along as a light weight passenger
> after that.
>
> The real key is a two piece or split ring held in place with a snap ring.
>
> Lowell
> ---
Lowell, I had to go take a look at what I actually did so I could remember. I
didn't like the idea of not being able to remove the push pull tube. I slit the
bearing to clear the bushing rivets and saftey wired it to secure it in the
metal ring in the fuselage. No epoxy. I put the inspection ring in the belly
incase the tube needs to be removed some time. I was going on memory on the
epoxy. Blame it on the sixtys. I'm sixty now.
--------
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=244297#244297
Message 8
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| Subject: | Charging System Theory - A few Questions |
Ok, I have a couple questions for people that are smarter than myself when it comes
to electronics. These questions have to do with the charging system and
how it works.
I've got a 914 and had a dual alternator setup on it for awhile...this worked flawlessly
until my external alternator crapped out on me. I had it rebuilt but
have not put it back on yet for many reasons, one being that it runs on the
vacuum pump gear which only turns .52:1 to the engine so it doesn't really come
alive until 3000 to 3500 rpm. This is not a problem by itself but I tend to
think that this type of loading may have lead to its early demise...probably
not but maybe. Anyway, I think the built-in generator provides just enough power
for my needs anyway but have a few questions on this setup. Here they are:
1. I flew for two hours this morning and the whole time my system voltage showed
14.0V on my EIS. Now I have an ammeter on the positive lead of the battery
showing amp draw in (+) or out (-) of battery. This varied consistently through
the two hour flight between +5 and -5 with most of the time around +2. The
battery is kept on a tender so it was completely charged when the flight started.
I was told by a guy at the airport that a battery will only take the amps
it needs as it needs them so a discharged, or low charged battery would take
and show more amps going in than a fully charged battery. Is this how it works?
2. I also was wondering about the regulator/rectifier. Does this regulate the
amount of power going to the battery? In other words, does it sense battery
voltage and send current as needed to the battery to maintain the charge or is
it always charging regardless of system or battery voltage?
After the flight, I checked my battery with my multi-meter and it show 13.0V so
it was still fully charged after two hours of flying so the system is obviously
working (again the EIS aslo showed 14.0V the entire flight), I am simply curious
as to how it works.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244303#244303
Message 9
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| Subject: | Re: Push pull tube bushing |
Tom,
I got you beat on the numbers game, but it just happens that is what I am
working on with the new project. My set-up is exactly what you came up
with. In fact I just removed the tube to alodyne it and it came out just as
you suggest. My bushing is also of the split variety, but with a snap ring.
Lowell
----- Original Message -----
From: "Tom Jones" <nahsikhs@elltel.net>
Sent: Saturday, May 16, 2009 4:13 PM
Subject: Kitfox-List: Re: Push pull tube bushing
>
>
> lcfitt(at)sbcglobal.net wrote:
>> Tom,
>>
>> I find this description interesting. If you glue the bushing in with
>> structural adhesive, and assuming this stuff sticks, the inspection ring
>> will be pretty much a cosmetic featrure as the rivets holding the rod end
>> stud will prevent the push/pull tube from sliding past the bushing. Also
>> if
>> the bushing is installed with the lip aft, it will not be removable. I
>> dealt with this years ago and after the ring slipped out, I replaced it
>> with
>> a split one and the old one just rode along as a light weight passenger
>> after that.
>>
>> The real key is a two piece or split ring held in place with a snap ring.
>>
>> Lowell
>> ---
>
>
> Lowell, I had to go take a look at what I actually did so I could
> remember. I didn't like the idea of not being able to remove the push
> pull tube. I slit the bearing to clear the bushing rivets and saftey
> wired it to secure it in the metal ring in the fuselage. No epoxy. I put
> the inspection ring in the belly incase the tube needs to be removed some
> time. I was going on memory on the epoxy. Blame it on the sixtys. I'm
> sixty now.
>
> --------
> 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=244297#244297
>
>
>
Message 10
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| Subject: | Re: Charging System Theory - A few Questions |
Darin, did you fly to Logan? =C2-A Kitfox landed and departed while I had
the Hatz up. =C2-After about 45 minutes over the airport the engine quit
. =C2-Will update for the interested when the cause is determined.
My understanding is that the voltage regulator does just that, regulates th
e voltage out of the alternator/generator to no more than 13.8 (Theoretical
ly). =C2-The generating beast puts out voltage more or less linearly acco
rding to rpm. =C2-You saw this with your gear drive alternator. =C2-My
understanding is as suggested that the battery draws the amps needs to beco
me charged. =C2-Can't understand why you would have negative amps unless
the equipment draw changed and exceeded the capacity of the alternator.
John
----- Original Message -----
From: "darinh" <gerns25@netscape.net>
Sent: Saturday, May 16, 2009 6:27:08 PM GMT -07:00 US/Canada Mountain
Subject: Kitfox-List: Charging System Theory - A few Questions
Ok, I have a couple questions for people that are smarter than myself when
it comes to electronics. =C2-These questions have to do with the charging
system and how it works.
I've got a 914 and had a dual alternator setup on it for awhile...this work
ed flawlessly until my external alternator crapped out on me. =C2-I had i
t rebuilt but have not put it back on yet for many reasons, one being that
it runs on the vacuum pump gear which only turns .52:1 to the engine so it
doesn't really come alive until 3000 to 3500 rpm. =C2-This is not a probl
em by itself but I tend to think that this type of loading may have lead to
its early demise...probably not but maybe. =C2-Anyway, I think the built
-in generator provides just enough power for my needs anyway but have a few
questions on this setup. =C2-Here they are:
1. I flew for two hours this morning and the whole time my system voltage s
howed 14.0V on my EIS. =C2-Now I have an ammeter on the positive lead of
the battery showing amp draw in (+) or out (-) of battery. =C2-This varie
d consistently through the two hour flight between +5 and -5 with most of t
he time around +2. =C2-The battery is kept on a tender so it was complete
ly charged when the flight started. =C2-I was told by a guy at the airpor
t that a battery will only take the amps it needs as it needs them so a dis
charged, or low charged battery would take and show more amps going in than
a fully charged battery. =C2-Is this how it works? =C2-
2. =C2-I also was wondering about the regulator/rectifier. =C2-Does thi
s regulate the amount of power going to the battery? =C2-In other words,
does it sense battery voltage and send current as needed to the battery to
maintain the charge or is it always charging regardless of system or batter
y voltage?
After the flight, I checked my battery with my multi-meter and it show 13.0
V so it was still fully charged after two hours of flying so the system is
obviously working (again the EIS aslo showed 14.0V the entire flight), I am
simply curious as to how it works.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244303#244303
===========
===========
MS -
===========
e -
=C2- =C2- =C2- =C2- =C2--Matt Dralle, List Admin.
===========
Message 11
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| Subject: | Re: Charging System Theory - A few Questions |
Hello Darin,
I'll take a crack at your questions. Although I am not a degreed
electronics engineer, I have worked my whole life as an electronics tech. I earned
my education in electronics through the United States Navy Avionics B
School. This is a course of study comparable to many university electronics
engineering programs of the time.
First, your aircraft does not have a true "charging system". It simply
has a battery and an alternator/regulator that are in parallel with each
other. They are both sources of DC power. The alternator and it's
rectifier/regulator work as a system that produce a regulated output voltage of
13.8 -
14 VDC. The Rotax built-in alternator has a very limited current output
capability and so that regulated output of 13.8 - 14 VDC may fall below it's
regulated voltage point if the ship's load is great enough.
One of the battery's purposes is to help stabilize the alternator's output
during these peak load times. That is why you see the ammeter show a
negative value at times. --The alternator is not keeping up with the power
demands of the ship's power bus and so the battery is supplying the deficit
power. It is suffering a net discharge.
When the battery's voltage drops below the output voltage of the
alternator's, --the battery is taking on a charge. It charges back up to the
applied voltage of 13.8 - 14 VDC This is true unless the ship's power buss is
using more power than the alternator can produce.
The fact that you see an average of +2 amps on your ammeter demonstrates
that on average you are producing enough power to the buss to supply all
system's needs and keep the battery charged. If you turned on your landing
lights, electric deicing boots, electric seat heater and your radar jamming
countermeasures transmitters, your average ammeter reading would be deep in
the negative and your battery would soon be dead.
The guy at your airport is essentially right in that the battery's fully
charged voltage is about 14 volts. It will not charge any higher than that
because the regulator's output is limited to that value. If the regulator
were to output a higher voltage, the fully charged battery would heat and
boil more electrolyte out and soon would go dry without attention. The
chemistry of the battery will not allow it to raise it's voltage too much
higher.
You may think of the battery and alternator as being in equilibrium most of
the time. The battery's voltage is pushing back at the alternator's
output and they are equal. When the battery's voltage is below this point,
some alternator current flows to it to charge it back up.
You can succeed in your arrangement as long as you know when your load is
exceeding your alternator's output and take action to reduce power
consumption as needed. As long as you average in the positive range of your ammeter
reading you should be good.
I don't think the gear ratio of your external alternator to shaft speed had
anything to do with it's failure. I would be curious to know what the
specific failure was though.
I hope this is helpful to you. There are others on the list who may be
able to offer more.
John P. Marzluf
Columbus, Ohio
Outback (out back in the garage)
In a message dated 5/16/2009 8:29:05 P.M. Eastern Daylight Time,
gerns25@netscape.net writes:
--> Kitfox-List message posted by: "darinh" <gerns25@netscape.net>
Ok, I have a couple questions for people that are smarter than myself when
it comes to electronics. These questions have to do with the charging
system and how it works.
I've got a 914 and had a dual alternator setup on it for awhile...this
worked flawlessly until my external alternator crapped out on me. I had it
rebuilt but have not put it back on yet for many reasons, one being that it
runs on the vacuum pump gear which only turns .52:1 to the engine so it
doesn't really come alive until 3000 to 3500 rpm. This is not a problem by
itself but I tend to think that this type of loading may have lead to its
early demise...probably not but maybe. Anyway, I think the built-in generator
provides just enough power for my needs anyway but have a few questions on
this setup. Here they are:
1. I flew for two hours this morning and the whole time my system voltage
showed 14.0V on my EIS. Now I have an ammeter on the positive lead of the
battery showing amp draw in (+) or out (-) of battery. This varied
consistently through the two hour flight between +5 and -5 with most of the time
around +2. The battery is kept on a tender so it was completely charged
when the flight started. I was told by a guy at the airport that a battery
will only take the amps it needs as it needs them so a discharged, or low
charged battery would take and show more amps going in than a fully charged
battery. Is this how it works?
2. I also was wondering about the regulator/rectifier. Does this
regulate the amount of power going to the battery? In other words, does it sense
battery voltage and send current as needed to the battery to maintain the
charge or is it always charging regardless of system or battery voltage?
After the flight, I checked my battery with my multi-meter and it show
13.0V so it was still fully charged after two hours of flying so the system is
obviously working (again the EIS aslo showed 14.0V the entire flight), I
am simply curious as to how it works.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244303#244303
**************An Excellent Credit Score is 750. See Yours in Just 2 Easy
Steps!
Excfooter51609NO62)
Message 12
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| Subject: | Charging System Theory - A few Questions |
1. That's pretty much it... A discharged battery will absorb current from
the generator. The purpose of the regulator is to keep the voltage high
enough so the pattery can absorb power... this is generally at 13.8V. BTW I
don't personally recommend putting the battery on a tender and leaving it
for extended periods of time. If you want to do that look into a pulse
charger. Even a small continuous current can boil a battery in time.
2. The regulator rectifier does two jobs. It converts AC current produced
by the alternator to DC current which your radios, etc use. It also keeps
the output of the alternator at around 13.8V As a discharged battery starts
to charge it will drop the voltage slightly causing the regulator to allow
the alternator to produce more current to keep the whole system at around
13.8V The further discharged your battery is the higher the ammeter + will
read. The voltage should remain more or less consist ant... That is the
job of the regulator.
Note there is a margin of usability on the voltage. 14.0 V is ok @ 15V I'd
land and check out things.
Noel
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of darinh
Sent: 16 May 2009 09:57 PM
Subject: Kitfox-List: Charging System Theory - A few Questions
Ok, I have a couple questions for people that are smarter than myself when
it comes to electronics. These questions have to do with the charging
system and how it works.
I've got a 914 and had a dual alternator setup on it for awhile...this
worked flawlessly until my external alternator crapped out on me. I had it
rebuilt but have not put it back on yet for many reasons, one being that it
runs on the vacuum pump gear which only turns .52:1 to the engine so it
doesn't really come alive until 3000 to 3500 rpm. This is not a problem by
itself but I tend to think that this type of loading may have lead to its
early demise...probably not but maybe. Anyway, I think the built-in
generator provides just enough power for my needs anyway but have a few
questions on this setup. Here they are:
1. I flew for two hours this morning and the whole time my system voltage
showed 14.0V on my EIS. Now I have an ammeter on the positive lead of the
battery showing amp draw in (+) or out (-) of battery. This varied
consistently through the two hour flight between +5 and -5 with most of the
time around +2. The battery is kept on a tender so it was completely
charged when the flight started. I was told by a guy at the airport that a
battery will only take the amps it needs as it needs them so a discharged,
or low charged battery would take and show more amps going in than a fully
charged battery. Is this how it works?
2. I also was wondering about the regulator/rectifier. Does this regulate
the amount of power going to the battery? In other words, does it sense
battery voltage and send current as needed to the battery to maintain the
charge or is it always charging regardless of system or battery voltage?
After the flight, I checked my battery with my multi-meter and it show 13.0V
so it was still fully charged after two hours of flying so the system is
obviously working (again the EIS aslo showed 14.0V the entire flight), I am
simply curious as to how it works.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244303#244303
Message 13
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| Subject: | Charging System Theory - A few Questions |
John:
That is exactly when the ammeter will go negative
Certified aircraft in Canada are only allowed to install loads to 80% or
the capacity of the alternator if they do not have a load meter. If
they do have a load meter they are allowed to install no more than 100%
of the generating capacity of their engine.
Homebuilt or amateur built aircraft can do as they please but for me the
80% rule is good common horse sense...
Noel
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of
kerrjohna@comcast.net
Sent: 16 May 2009 11:21 PM
Subject: Re: Kitfox-List: Charging System Theory - A few Questions
Darin, did you fly to Logan? A Kitfox landed and departed while I had
the Hatz up. After about 45 minutes over the airport the engine quit.
Will update for the interested when the cause is determined.
My understanding is that the voltage regulator does just that, regulates
the voltage out of the alternator/generator to no more than 13.8
(Theoretically). The generating beast puts out voltage more or less
linearly according to rpm. You saw this with your gear drive
alternator. My understanding is as suggested that the battery draws the
amps needs to become charged. Can't understand why you would have
negative amps unless the equipment draw changed and exceeded the
capacity of the alternator.
John
----- Original Message -----
From: "darinh" <gerns25@netscape.net>
Sent: Saturday, May 16, 2009 6:27:08 PM GMT -07:00 US/Canada Mountain
Subject: Kitfox-List: Charging System Theory - A few Questions
Ok, I have a couple questions for people that are smarter than myself
when it comes to electronics. These questions have to do with the
charging system and how it works.
I've got a 914 and had a dual alternator setup on it for awhile...this
worked flawlessly until my external alternator crapped out on me. I had
it rebuilt but have not put it back on yet for many reasons, one being
that it runs on the vacuum pump gear which only turns .52:1 to the
engine so it doesn't really come alive until 3000 to 3500 rpm. This is
not a problem by itself but I tend to think that this type of loading
may have lead to its early demise...probably not but maybe. Anyway, I
think the built-in generator provides just enough power for my needs
anyway but have a few questions on this setup. Here they are:
1. I flew for two hours this morning and the whole time my system
voltage showed 14.0V on my EIS. Now I have an ammeter on the positive
lead of the battery showing amp draw in (+) or out (-) of battery. This
varied consistently through the two hour flight between +5 and -5 with
most of the time around +2. The battery is kept on a tender so it was
completely charged when the flight started. I was told by a guy at the
airport that a battery will only take the amps it needs as it needs them
so a discharged, or low charged battery would take and show more amps
going in than a fully charged battery. Is this how it works?
2. I also was wondering about the regulator/rectifier. Does this
regulate the amount of power going to the battery? In other words, does
it sense battery voltage and send current as needed to the battery to
maintain the charge or is it always charging regardless of system or
battery voltage?
After the flight, I checked my battery with my multi-meter and it show
13.0V so it was still fully charged after two hours of flying so the
system is obviously working (again the EIS aslo showed 14.0V the entire
flight), I am simply curious as to how it works.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php? - MATRONICS WEB
FORUMS -
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Message 14
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| Subject: | Charging System Theory - A few Questions |
A very nice description... Much better than my hack at it! I take it
military aircraft are allowed to have more equipment thant 100% of
generating capacity on board.
noel
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of KITFOXZ@aol.com
Sent: 17 May 2009 12:01 AM
Subject: Re: Kitfox-List: Charging System Theory - A few Questions
Hello Darin,
I'll take a crack at your questions. Although I am not a degreed
electronics engineer, I have worked my whole life as an electronics tech. I
earned my education in electronics through the United States Navy Avionics B
School. This is a course of study comparable to many university electronics
engineering programs of the time.
First, your aircraft does not have a true "charging system". It simply has
a battery and an alternator/regulator that are in parallel with each other.
They are both sources of DC power. The alternator and it's
rectifier/regulator work as a system that produce a regulated output voltage
of 13.8 - 14 VDC. The Rotax built-in alternator has a very limited current
output capability and so that regulated output of 13.8 - 14 VDC may fall
below it's regulated voltage point if the ship's load is great enough.
One of the battery's purposes is to help stabilize the alternator's output
during these peak load times. That is why you see the ammeter show a
negative value at times. --The alternator is not keeping up with the power
demands of the ship's power bus and so the battery is supplying the deficit
power. It is suffering a net discharge.
When the battery's voltage drops below the output voltage of the
alternator's, --the battery is taking on a charge. It charges back up to
the applied voltage of 13.8 - 14 VDC This is true unless the ship's power
buss is using more power than the alternator can produce.
The fact that you see an average of +2 amps on your ammeter demonstrates
that on average you are producing enough power to the buss to supply all
system's needs and keep the battery charged. If you turned on your landing
lights, electric deicing boots, electric seat heater and your radar jamming
countermeasures transmitters, your average ammeter reading would be deep in
the negative and your battery would soon be dead.
The guy at your airport is essentially right in that the battery's fully
charged voltage is about 14 volts. It will not charge any higher than that
because the regulator's output is limited to that value. If the regulator
were to output a higher voltage, the fully charged battery would heat and
boil more electrolyte out and soon would go dry without attention. The
chemistry of the battery will not allow it to raise it's voltage too much
higher.
You may think of the battery and alternator as being in equilibrium most of
the time. The battery's voltage is pushing back at the alternator's output
and they are equal. When the battery's voltage is below this point, some
alternator current flows to it to charge it back up.
You can succeed in your arrangement as long as you know when your load is
exceeding your alternator's output and take action to reduce power
consumption as needed. As long as you average in the positive range of your
ammeter reading you should be good.
I don't think the gear ratio of your external alternator to shaft speed had
anything to do with it's failure. I would be curious to know what the
specific failure was though.
I hope this is helpful to you. There are others on the list who may be able
to offer more.
John P. Marzluf
Columbus, Ohio
Outback (out back in the garage)
In a message dated 5/16/2009 8:29:05 P.M. Eastern Daylight Time,
gerns25@netscape.net writes:
Ok, I have a couple questions for people that are smarter than myself when
it comes to electronics. These questions have to do with the charging
system and how it works.
I've got a 914 and had a dual alternator setup on it for awhile...this
worked flawlessly until my external alternator crapped out on me. I had it
rebuilt but have not put it back on yet for many reasons, one being that it
runs on the vacuum pump gear which only turns .52:1 to the engine so it
doesn't really come alive until 3000 to 3500 rpm. This is not a problem by
itself but I tend to think that this type of loading may have lead to its
early demise...probably not but maybe. Anyway, I think the built-in
generator provides just enough power for my needs anyway but have a few
questions on this setup. Here they are:
1. I flew for two hours this morning and the whole time my system voltage
showed 14.0V on my EIS. Now I have an ammeter on the positive lead of the
battery showing amp draw in (+) or out (-) of battery. This varied
consistently through the two hour flight between +5 and -5 with most of the
time around +2. The battery is kept on a tender so it was completely
charged when the flight started. I was told by a guy at the airport that a
battery will only take the amps it needs as it needs them so a discharged,
or low charged battery would take and show more amps going in than a fully
charged battery. Is this how it works?
2. I also was wondering about the regulator/rectifier. Does this regulate
the amount of power going to the battery? In other words, does it sense
battery voltage and send current as needed to the battery to maintain the
charge or is it always charging regardless of system or battery voltage?
After the flight, I checked my battery with my multi-meter and it show 13.0V
so it was still fully charged after two hours of flying so the system is
obviously working (again the EIS aslo showed 14.0V the entire flight), I am
simply curious as to how it works.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244303#244303==================
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| Subject: | Re: Charging System Theory - A few Questions |
[quote="kerrjohna(at)comcast.net"]Darin, did you fly to Logan? A Kitfox landed
and departed while I had the Hatz up. After about 45 minutes over the airport
the engine quit. Will update for the interested when the cause is determined.
[quote]
Yes John that was me. I saw you with your Hatz out and thought that was you orbiting
the airport. I heard you make the call and stayed on the radio until I
heard you announce "high final...dead stick" and thought at least you had made
it to the runway. Sounds like it was a successful deadstick landing though
and that is good. I for one would be interested in hearing the cause when you
find it. By the way, that is a beautiful biplane! Nice job.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244331#244331
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| Subject: | Re: Charging System Theory - A few Questions |
kerrjohna(at)comcast.net wrote:
> Darin, did you fly to Logan? A Kitfox landed and departed while I had the Hatz
up.---
Yes John that was me. I saw you with your Hatz out and thought that was you orbiting
the airport. I heard you make the call and stayed on the radio until I
heard you announce "high final...dead stick" and thought at least you had made
it to the runway. Sounds like it was a successful deadstick landing though
and that is good. I for one would be interested in hearing the cause when you
find it. By the way, that is a beautiful biplane! Nice job.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244332#244332
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| Subject: | Re: Charging System Theory - A few Questions |
KITFOXZ(at)aol.com wrote:
> Hello Darin,
>
> I'll take a crack at your questions. Although I am not a degreed electronics
engineer, I have worked my whole life as an electronics tech. I earned my
education in electronics through the United States Navy Avionics B School. This
is a course of study comparable to many university electronics engineering
programs of the time.
>
> First, your aircraft does not have a true "charging system". It simply has
a battery and an alternator/regulator that are in parallel with each other.
They are both sources of DC power. The alternator and it's rectifier/regulator
work as a system that produce a regulated output voltage of 13.8 - 14 VDC.
The Rotax built-in alternator has a very limited current output capability
and so that regulated output of 13.8 - 14 VDC may fall below it's regulated
voltage point if the ship's load is great enough.
>
> One of the battery's purposes is to help stabilize the alternator's output
during these peak load times. That is why you see the ammeter show a negative
value at times. --The alternator is not keeping up with the power demands
of the ship's power bus and so the battery is supplying the deficit power. It
is suffering a net discharge.....
>
> John P. Marzluf
> Columbus, Ohio
> Outback (out back in the garage)
>
>
John,
Thanks for that reply...answered all my questions and them some! That all makes
sense and is basically how I understood the system but was not sure. The fact
is that I would like to be able to run my lighting, strobes and navs along
with a few other things like my deicing boots and radar jamming counter measures
transmitters (actually just my heater fans) so I need to get my other alternator
back on and see why it is causing my oil temp gauge to fluctuate wildly.
Which brings up another question (I'll make it blue text to stand out):
Do I need another noise suppression capacitor on bolt on alternator? it is the
same (or very similar) to the Rotax add-on altenator but it runs on the vacuum
pump pad. It is internally regulated and rectified but does not have any internal
noise suppression. I noticed that the wiring diagram in my engine installation
manual shows the add-on alternator requiring a capacitor also. I ask
because someone told me I didn't need one on both onboard and add-on alternators
but it is there in the manual. I ordered one from John and have it so I am
going to put it on unless someone can tell me why I don't need it. I get quite
a bit of noise from it when I transmit...to the point that the tower has a
hard time understanding. This doesn't happen when running on the Rotax generator
that is on a capacitor.
By the way, the alternator coil leads broke. The shop that rebuilt it said the
original leads were very small and brittle and a couple other broke just in the
disassembly. Apparently, the place that supplied the alternator did quite
a bit of custom machining (custom shaft with spline gear, mount and stock mounting
bracket removal) but the attachment of the coil leads was pretty crappy.
They are now done with larger copper and ring terminals on each lead. It is
a Nippondenso 60A alternator if you are curious but turned down like it is it
only produce 30A - 40A....plenty for my bird.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=244335#244335
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