Today's Message Index:
----------------------
1. 05:46 AM - Re: Norwegian Stalls (Larry Martin)
2. 05:59 AM - Re: Model 4 engine swap (Bob)
3. 06:08 AM - Re: Norwegian Stalls (Bob)
4. 06:42 AM - Re: Broken Skylight (Tom Jones)
5. 09:12 AM - Re: Re: Norwegian Stalls (Guy Buchanan)
6. 01:34 PM - 5V Converter (Off Topic) (Nick Scholtes)
7. 02:32 PM - Re: Re: Norwegian Stalls (Michel Verheughe)
8. 03:11 PM - Re: Re: Norwegian Stalls (dave)
9. 03:22 PM - Re: Re: Norwegian Stalls (kerrjohna@comcast.net)
10. 04:15 PM - Re: 5V Converter (Off Topic) (Noel Loveys)
11. 04:17 PM - Re: 5V Converter (Off Topic) do not archive (TC)
12. 07:13 PM - Re: Sportflight (jeff puls)
13. 07:25 PM - New Kitfox Videos (dave)
14. 07:32 PM - Re: Re: Norwegian Stalls (Guy Buchanan)
15. 08:01 PM - Re: New Kitfox Videos how do you post vid? (Aerobatics@aol.com)
16. 08:04 PM - Re: Re: Jabiru vs. Rotax. WAS: Rear spar attach reinforcement (James Shumaker)
17. 08:57 PM - Re: New Kitfox Videos (Aerobatics@aol.com)
Message 1
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| Subject: | Re: Norwegian Stalls |
"....the horizontal stab (and the elevator) will stall too, and the nose
will drop."
I don't think that this is correct. If the stab was to stall, the
nose will pitch up. aka F101 Voodoo. The stab provides a downward
force. The elevator will loose authority, but again can't stall as the
wings do.
"...Is this correct?: When we stall gently (mush down), the plane starts
stalling the wings first then, if we keep the stick in the stomach, and
provided we get enough elevator authority to get the nose up and the
speed down, the horizontal stab (and the
elevator) will stall too, and the nose will drop..."
You are correct that the wings "starts" to stall. Most modern planes
are designed so that the wing will stall in stages. Actually, only part
of the wing stalls, the other part is still flying. The plane will mush
because the weight of the plane now exceeds the amount of lift that the
wings can produce at that angle of attach. If you lob the nose up and
gently keep 0 G on - not requiring the wings to provide any lift - it is
possible to fly at 0 airspeed. Actually, you are not flying since you
will not be overcoming gravity, but the airplane will not stall. You
can hold 0 airspeed and still roll the wings to lower the nose letting
it drop and now gently obtain airspeed. Just a hair more G than 0 and
more lift is required out of the wing and it would stall at the angle of
attach.
To see how the wing stalls all at once as you approach your level
flight stall speed lob the nose up about 20 degrees and release the back
pressure. You will notice that the IAS will be less than "normal" and
the nose will drop more abruptly than "normal". This will occur because
all of the wing is stalling at about the same time, instead of a part of
the wing stalling.
I know that this doesn't help you find you thud, but.....
larry
Message 2
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| Subject: | Re: Model 4 engine swap |
I'm a new guy to the group and just bought a part-built model V kit. I still have
an A&P from when I did that for a living, but now work as an engineer and
usually on big planes.
Going to higher power engines is pretty common and undocumented changes happen.
However, from the legal standpoint, I can comfortably say that the change from
a 80hp Rotax to 100hp is a major modification and the FAA believes that they
should be notified. I'd expect questions about how you've changed your (legally
and insurance-required) flight manual to reflect the changes in climb rate,
take-off distance, fuel consumption, range, etc. If the inspector isn't that
familiar with the R-912 series, possibly whether you've had to change tach markings,
or your Instructions for Continuing Airworthiness (ICA) to reflect any
change in engine TBO.
Write down what you did in a letter to the local FSDO in very factual form, like
a log entry, including your Kitfox s/n, N#, engine type & s/n (old and new),
and attach copies of the changed pages of your manual. Include a statement that
there is no change to ICA or weight and balance. I'd also add a sentence
about how the factory-delivered kits used the same engine and FWF components,
or how similar this is to existing and approved airplanes just like yours. The
FAA is looking for the engineering basis of the changes and you just have to
document them. At the end of the letter, add that you look forward to the response
and are ready to answer any further questions. This letter will ultimately
go into the permanent archives for your airplane's N#, so don't write something
that might haunt you later. (How you hate dealing with the FAA wouldn't
be a good thing.) Have your local IA or A&P proof read it. I call the local
FSDO, get an inspector's name to put on the letter, then fax him a copy before
mailing. It just goes faster if you have somebody to talk to.
One other consideration if you're thinking about not reporting is that the change
can affect your sale of the plane later. The buyer's pre-buy inspection will
catch the change and so will his insurance company. I just turned down buying
an airplane, but it was an extreme case. The log showed the airplane had
a 912 and the actual airplane had a 582!
Bob
A&P, Aircraft Systems Engineer
--------
Remember that internet advice may only be worth what you pay.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=86290#86290
Message 3
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| Subject: | Re: Norwegian Stalls |
You've written about this for quite a while, so if fabric was coming off, I'd think
you would've seen something by now. As the attitude and loads change, stuff
moves around quite a lot. I chased a grinding in the tailcone noise something
kind of like this in a Cessna and it turned out the ELT cable rubbed on a
frame as the instructors would do stalls and turns. Are you sure it's not something
simple like an item rubbing the fabric? Maybe the cargo liner?
Bob
--------
Remember that internet advice may only be worth what you pay.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=86293#86293
Message 4
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| Subject: | Re: Broken Skylight |
Grant,
I can remember one case of a kitfox lexan windscreen cracking with a loud bang
in flight. It was in winter and the temperature was very cold. With the help
of an A&P, the owner drilled and safety wired it together and flew it for another
few days that way.
Do you have a theory as to why your skylight broke? I gather from your other post
that yours is not lexan.
Tom Jones
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=86300#86300
Message 5
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| Subject: | Re: Norwegian Stalls |
At 05:45 AM 1/8/2007, you wrote:
>"....the horizontal stab (and the elevator) will stall too, and the nose
>will drop."
>
> I don't think that this is correct. If the stab was to stall, the nose
> will pitch up. aka F101 Voodoo. The stab provides a downward force. The
> elevator will loose authority, but again can't stall as the wings do.
>
Sorry Larry; the stab "lifts" down, particularly with the stick in your
lap. It's most definitely possible to stall it too, after all it's only a
lifting airfoil. Most stabs don't stall because they're designed not to.
Certificated aircraft are designed to stall their wings long before the
horizontal stab stalls because were it to be otherwise you would have
really horrific landing behavior. (Picture a severe pitch over at flare
followed by a negative-g drive into the ground.) Anything's possible in
experimental land since many designers push the performance envelope
severely. All my experience with my Kitfox, however, indicates quite
normal, "certificated" behavior at all angle of attacks. I can even do the
"falling leaf" with the stick in my lap. (It really is a falling leaf,
since I have very little dihedral and my plane tends to fall off the
"bubble" to one side or the other.)
Guy
Message 6
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| Subject: | 5V Converter (Off Topic) |
Hi Guys,
My "real job" is being an electrical engineer, so if I "geek out" too
much here, just slap me.......
Regarding the topic of trickle charging through a cigarette lighter plug
and having to turn the Master on and off, there is a work-around. What
you can do is put a diode in parallel with the Master switch (anode
connected to the cigarette lighter, cathode to the inboard side of the
Master switch). This makes it so that when the Master switch is turned
ON, current can flow either into the system or out of the system. But,
when the Master switch is turned OFF, current can only flow INTO the
system, hence you will only be able to trickle-charge (current flowing
IN) when the Master is off, and if you left a load plugged into the
cigarette lighter the diode would prevent it from pulling current when
the Master is off. This would alleviate the need to do anything
manually to configure breakers or switches, which I know I'd forget to
do sometime........
Regarding using a 7805, here are some thoughts. It says on the
datasheet that the 7805 can output "up to" 1 Amp. But that isn't really
the limiting factor, the heat dissipation is. The TO-220 package (which
is what the 7805 comes in) can reasonably dissipate about .75 watts if
it is not heat-sinked, and it can dissipate about 2 watts if it is
heat-sinked really well (like sitting at the bottom of Lake Michigan!)
To calculate the wattage that it dissipates, just take the voltage that
is across it, and multiply by the current through it (power = voltage *
current). Since you've got a 12V system and the 7805 outputs 5V, you've
got 7V across the 7805 (more than this really, because a 12V system
typically runs between 12.8 and 13.3 or so). So, to get .75 watts
dissipated in the device, you can pull about 0.1 amps out of the
device. As Luis stated, pulling 400 mA out of the device will be
dissipating 2.8 watts which will get it pretty darn hot without a
heatsink, and even with a very good heatsink it will still get pretty
hot, easily hot enough to burn you. Max junction temp is 125C, and 2.8
W un-heat-sinked will get it up higher than that (on a hot day with a
hot ambient temperature). Realistically, a non-heat-sinked 7805 in a
12V system will only be useful up to about 100 mA, which is useful for
many things, but not a PDA on full bright that draws 400 mA.
An alternative is an actual switching converter. You can get those at
various places like Digi-Key. I only spent a minute looking for one,
but here's one for about $15 or so, and I'm sure if you looked you could
find one quite a bit cheaper than that:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=296&M=PT78ST105H
A switching converter like this is better than 80% efficient, so only
20% of the total power consumed is dissipated in the device. So your
PDA draws 2 W (5V*.4A), which means that the converter will only
dissipate .5W, which it can handle no-problem.
The comment about using multiple 7805 in parallel is definitely a
practice to be avoided. The problem here is that the 7805, being a
power source, has a low-impedance output. If you connect two
low-impedance outputs together, and if they are not exactly matched, one
will put out just a tiny bit higher voltage than the other, and since
they are low impedance, the high one will feed a huge amount of current
to the low one. The only way to realistically "load share" using two
low-impedance outputs is to put a diode in series with each output, but
again this isn't a very good solution because the output/diode
combination that puts out the higher voltage will end up doing all the
work and it won't truly be "sharing".
Sorry for "geeking out" on you!
Best Regards,
Nick Scholtes
Time: 11:09:55 AM PST US
From: "Noel Loveys" <noelloveys@yahoo.ca>
Subject: RE: Kitfox-List: Re: Question for PDA GPS users: Hooking up power.
Correct you would have to leave the master and the power outlet breakers in
to trickle charge the battery...Max current 70% the amp value of the
breaker. Remember to pull the breakers on everything else.
The DC to DC adapters do consume a small (almost tiny) amount of current
even while under no load but that is why you have master switches and as I
recommend an accessory beaker between the power outlets and the main buss.
You could use several 7805 in parallel to attain the current you will need.
Keep a good heat sink on all of them. I used one on a converter I built for
a digital camera. I could get three pics before the circuit board got too
hot for my liking. The answer was to install a resistor in series with the
camera to reduce the load at the converter. I didn't mind waiting an extra
second or two for the camera to cycle. It's been working well for just
under ten years now.
Noel
> -----Original Message-----
> From: owner-kitfox-list-server@matronics.com
> [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of wingnut
> Sent: Sunday, January 07, 2007 11:24 AM
> To: kitfox-list@matronics.com
> Subject: Kitfox-List: Re: Question for PDA GPS users: Hooking
> up power.
>
>
>
> Thanks for all the help guys. I like the idea of being able
> to use the power outlet to trickle charge the main battery.
> There's one snag though; In order to do this, the power
> outlet would have to bypass the master switch so I wouldn't
> be able to turn it off. Most of these car adapters draw some
> current even with no load so I'll have to remember to reach
> under the panel and pull the adapter or it will drain my battery.
>
> I think what I'll do is start off with the power outlet but
> eventually transition to some sort of DC to DC converter like
> one of these: http://www.powerstream.com/dda.htm
>
> It's a bit expensive at $30 but it's a nice package with
> integrated mounting flanges making it easy to bolt to the
> firewall. I tried using a 7805 and but was getting rather hot
> to the touch with just the PDA attached. I was surprised but
> when I looked up the specs I found that they're limited to
> 400mA. That's right on the edge of what my PDA is drawing at
> full bright.
>
> Thaks again for all the help.
> -Luis
>
>
>
>
> Read this topic online here:
>
Message 7
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| Subject: | Re: Norwegian Stalls |
On Jan 8, 2007, at 5:49 PM, Guy Buchanan wrote:
> Sorry Larry; the stab "lifts" down, particularly with the stick in
> your lap.
Wow, this is interesting stuff, Larry and Guy! Now, I have a friend
building a Velocity and he told me that a canard doesn't stall the
wings because the canard wings stalls first and the nose drops, hence
gaining speed.
With our Kitfoxes, the wings stalls before the horizontal stab. Makes
sense. And when our nose drops, it's because the wings stalls first
and the horizontal stab "holds" the tail up.
But when we mush down, then, what happens? Honestly, I am not sure I
know what I am talking about because "mush down" is a word I came to
know from its context, but from a proper definition.
Say, when I put the engine on idle, then gently pull the stick, trying
to keep the same altitude and watch the speed decrease to near stall
speed. At the end of it, I have the stick to the most backward
position, I feel the plane trembling, a wing or the other drops, which
I correct with a bit of rudder and aileron, to keep the ball centered,
then I can't get any slower because I sink now maybe 500 fpm. This is
mushing down, right? At that moment, the wings are partially stalled,
right? And the elevator is not? But why doesn't the nose drops then?
By the way, does anyone know the relative angle between the wings and
horizontal stabs on our Kitfoxes?
Cheers,
Michel
do not archive
Message 8
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| Subject: | Re: Norwegian Stalls |
Michel, I can measure the differance if you like in degrees if you let me
know.
Also when my floats go on , I drop the front of the horiz.stab about one
inch an I fly hands free.
the angle does change but the elevator still has the same authority. As a
matter if fact i can drag the tails of the floats down the runway when
landing with gear down. The wear on bottom of the floats shows this
clearly.
I think the disturbed air from the stalled wing is hitting my tail section
some how and causing a thud. I will do further testing this week and let
you know the results - deadstick and headset off so I an hear it .
Dave
----- Original Message -----
From: "Michel Verheughe" <michel@online.no>
Sent: Monday, January 08, 2007 5:28 PM
Subject: Re: Kitfox-List: Re: Norwegian Stalls
>
> On Jan 8, 2007, at 5:49 PM, Guy Buchanan wrote:
>> Sorry Larry; the stab "lifts" down, particularly with the stick in your
>> lap.
>
> Wow, this is interesting stuff, Larry and Guy! Now, I have a friend
> building a Velocity and he told me that a canard doesn't stall the wings
> because the canard wings stalls first and the nose drops, hence gaining
> speed.
> With our Kitfoxes, the wings stalls before the horizontal stab. Makes
> sense. And when our nose drops, it's because the wings stalls first and
> the horizontal stab "holds" the tail up.
> But when we mush down, then, what happens? Honestly, I am not sure I know
> what I am talking about because "mush down" is a word I came to know from
> its context, but from a proper definition.
> Say, when I put the engine on idle, then gently pull the stick, trying to
> keep the same altitude and watch the speed decrease to near stall speed.
> At the end of it, I have the stick to the most backward position, I feel
> the plane trembling, a wing or the other drops, which I correct with a bit
> of rudder and aileron, to keep the ball centered, then I can't get any
> slower because I sink now maybe 500 fpm. This is mushing down, right? At
> that moment, the wings are partially stalled, right? And the elevator is
> not? But why doesn't the nose drops then?
> By the way, does anyone know the relative angle between the wings and
> horizontal stabs on our Kitfoxes?
>
> Cheers,
> Michel
>
> do not archive
>
>
>
Message 9
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| Subject: | Re: Norwegian Stalls |
Michael, the maneuver you have described is called "falling leaf". It is not so
much a stall as operating at a point of minimum lift. My instructor made me
practice it with a Super Cub at idle to ingrain in me the notion of lifting the
wing with rudder rather than aileron.
John Kerr
-------------- Original message --------------
From: Michel Verheughe <michel@online.no>
>
> On Jan 8, 2007, at 5:49 PM, Guy Buchanan wrote:
> > Sorry Larry; the stab "lifts" down, particularly with the stick in
> > your lap.
>
> Wow, this is interesting stuff, Larry and Guy! Now, I have a friend
> building a Velocity and he told me that a canard doesn't stall the
> wings because the canard wings stalls first and the nose drops, hence
> gaining speed.
> With our Kitfoxes, the wings stalls before the horizontal stab. Makes
> sense. And when our nose drops, it's because the wings stalls first
> and the horizontal stab "holds" the tail up.
> But when we mush down, then, what happens? Honestly, I am not sure I
> know what I am talking about because "mush down" is a word I came to
> know from its context, but from a proper definition.
> Say, when I put the engine on idle, then gently pull the stick, trying
> to keep the same altitude and watch the speed decrease to near stall
> speed. At the end of it, I have the stick to the most backward
> position, I feel the plane trembling, a wing or the other drops, which
> I correct with a bit of rudder and aileron, to keep the ball centered,
> then I can't get any slower because I sink now maybe 500 fpm. This is
> mushing down, right? At that moment, the wings are partially stalled,
> right? And the elevator is not? But why doesn't the nose drops then?
> By the way, does anyone know the relative angle between the wings and
> horizontal stabs on our Kitfoxes?
>
> Cheers,
> Michel
>
> do not archive
>
>
>
>
>
<html><body>
<DIV>Michael, the maneuver you have described is called "falling leaf". It
is not so much a stall as operating at a point of minimum lift. My instructor
made me practice it with a Super Cub at idle to ingrain in me the notion
of lifting the wing with rudder rather than aileron.</DIV>
<DIV> </DIV>
<DIV>John Kerr</DIV>
<DIV> </DIV>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px
solid">-------------- Original message -------------- <BR>From: Michel Verheughe
<michel@online.no> <BR><BR>> --> Kitfox-List message posted by:
Michel Verheughe <MICHEL@ONLINE.NO><BR>> <BR>> On Jan 8, 2007, at 5:49
PM, Guy Buchanan wrote: <BR>> > Sorry Larry; the stab "lifts" down, particularly
with the stick in <BR>> > your lap. <BR>> <BR>> Wow, this
is interesting stuff, Larry and Guy! Now, I have a friend <BR>> building
a Velocity and he told me that a canard doesn't stall the <BR>> wings because
the canard wings stalls first and the nose drops, hence <BR>> gaining speed.
<BR>> With our Kitfoxes, the wings stalls before the horizontal stab.
Makes <BR>> sense. And when our nose drops, it's because the wings stalls
first <BR>> and the horizontal stab "holds" the tail up. <BR>> But when
we mush down, then, what happens? Honestly, I am not
sure I
<BR>> know what I am talking about because "mush down" is a word I came to
<BR>> know from its context, but from a proper definition. <BR>> Say, when
I put the engine on idle, then gently pull the stick, trying <BR>> to keep
the same altitude and watch the speed decrease to near stall <BR>> speed.
At the end of it, I have the stick to the most backward <BR>> position, I
feel the plane trembling, a wing or the other drops, which <BR>> I correct
with a bit of rudder and aileron, to keep the ball centered, <BR>> then I
can't get any slower because I sink now maybe 500 fpm. This is <BR>> mushing
down, right? At that moment, the wings are partially stalled, <BR>> right?
And the elevator is not? But why doesn't the nose drops then? <BR>> By the
way, does anyone know the relative angle between the wings and <BR>> horizontal
stabs on our Kitfoxes? <BR>> <BR>> Cheers, <BR>> Michel <BR>>
<BR>> do not archive <BR>> <BR>> <BR>>
<pre><b><font size=2 color="#000000" face="courier new,courier">
</b></font></pre></body></html>
Message 10
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| Subject: | 5V Converter (Off Topic) |
Thanks Nick
I should have thought about the diode across the master myself. It's a nice
simple failsafe charge circuit.
I wasn't aware of the low impedance output of the 7805 chip but I can
certainly see what you are saying. The switching converter seems to be the
answer.
While you are on the line....
I have an old Icom 02-AT Handy which has a DC to DC converter built in that
allows the radio to operate over a fairly wide range of voltages including
directly off a car accessory outlet. Do you know of any reason that Icom
not install the same technology in the IC - A24?
Noel
> -----Original Message-----
> From: owner-kitfox-list-server@matronics.com
> [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of
> Nick Scholtes
> Sent: Monday, January 08, 2007 6:00 PM
> To: kitfox-list@matronics.com
> Subject: Kitfox-List: 5V Converter (Off Topic)
>
>
>
> Hi Guys,
>
> My "real job" is being an electrical engineer, so if I "geek out" too
> much here, just slap me.......
>
> Regarding the topic of trickle charging through a cigarette
> lighter plug
> and having to turn the Master on and off, there is a
> work-around. What
> you can do is put a diode in parallel with the Master switch (anode
> connected to the cigarette lighter, cathode to the inboard
> side of the
> Master switch). This makes it so that when the Master switch
> is turned
> ON, current can flow either into the system or out of the
> system. But,
> when the Master switch is turned OFF, current can only flow INTO the
> system, hence you will only be able to trickle-charge
> (current flowing
> IN) when the Master is off, and if you left a load plugged into the
> cigarette lighter the diode would prevent it from pulling
> current when
> the Master is off. This would alleviate the need to do anything
> manually to configure breakers or switches, which I know I'd
> forget to
> do sometime........
>
> Regarding using a 7805, here are some thoughts. It says on the
> datasheet that the 7805 can output "up to" 1 Amp. But that
> isn't really
> the limiting factor, the heat dissipation is. The TO-220
> package (which
> is what the 7805 comes in) can reasonably dissipate about .75
> watts if
> it is not heat-sinked, and it can dissipate about 2 watts if it is
> heat-sinked really well (like sitting at the bottom of Lake
> Michigan!)
> To calculate the wattage that it dissipates, just take the
> voltage that
> is across it, and multiply by the current through it (power =
> voltage *
> current). Since you've got a 12V system and the 7805 outputs
> 5V, you've
> got 7V across the 7805 (more than this really, because a 12V system
> typically runs between 12.8 and 13.3 or so). So, to get .75 watts
> dissipated in the device, you can pull about 0.1 amps out of the
> device. As Luis stated, pulling 400 mA out of the device will be
> dissipating 2.8 watts which will get it pretty darn hot without a
> heatsink, and even with a very good heatsink it will still get pretty
> hot, easily hot enough to burn you. Max junction temp is
> 125C, and 2.8
> W un-heat-sinked will get it up higher than that (on a hot day with a
> hot ambient temperature). Realistically, a non-heat-sinked 7805 in a
> 12V system will only be useful up to about 100 mA, which is
> useful for
> many things, but not a PDA on full bright that draws 400 mA.
>
> An alternative is an actual switching converter. You can get
> those at
> various places like Digi-Key. I only spent a minute looking for one,
> but here's one for about $15 or so, and I'm sure if you
> looked you could
> find one quite a bit cheaper than that:
>
> http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=296
> &M=PT78ST105H
>
> A switching converter like this is better than 80% efficient, so only
> 20% of the total power consumed is dissipated in the device. So your
> PDA draws 2 W (5V*.4A), which means that the converter will only
> dissipate .5W, which it can handle no-problem.
>
> The comment about using multiple 7805 in parallel is definitely a
> practice to be avoided. The problem here is that the 7805, being a
> power source, has a low-impedance output. If you connect two
> low-impedance outputs together, and if they are not exactly
> matched, one
> will put out just a tiny bit higher voltage than the other, and since
> they are low impedance, the high one will feed a huge amount
> of current
> to the low one. The only way to realistically "load share" using two
> low-impedance outputs is to put a diode in series with each
> output, but
> again this isn't a very good solution because the output/diode
> combination that puts out the higher voltage will end up
> doing all the
> work and it won't truly be "sharing".
>
> Sorry for "geeking out" on you!
>
> Best Regards,
>
> Nick Scholtes
>
>
>
> Time: 11:09:55 AM PST US
> From: "Noel Loveys" <noelloveys@yahoo.ca>
> Subject: RE: Kitfox-List: Re: Question for PDA GPS users:
> Hooking up power.
>
>
> Correct you would have to leave the master and the power
> outlet breakers in
> to trickle charge the battery...Max current 70% the amp value of the
> breaker. Remember to pull the breakers on everything else.
>
> The DC to DC adapters do consume a small (almost tiny) amount
> of current
> even while under no load but that is why you have master
> switches and as I
> recommend an accessory beaker between the power outlets and
> the main buss.
>
> You could use several 7805 in parallel to attain the current
> you will need.
> Keep a good heat sink on all of them. I used one on a
> converter I built for
> a digital camera. I could get three pics before the circuit
> board got too
> hot for my liking. The answer was to install a resistor in
> series with the
> camera to reduce the load at the converter. I didn't mind
> waiting an extra
> second or two for the camera to cycle. It's been working
> well for just
> under ten years now.
>
> Noel
>
>
> > -----Original Message-----
> > From: owner-kitfox-list-server@matronics.com
> > [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of wingnut
> > Sent: Sunday, January 07, 2007 11:24 AM
> > To: kitfox-list@matronics.com
> > Subject: Kitfox-List: Re: Question for PDA GPS users: Hooking
> > up power.
> >
> >
> >
> > Thanks for all the help guys. I like the idea of being able
> > to use the power outlet to trickle charge the main battery.
> > There's one snag though; In order to do this, the power
> > outlet would have to bypass the master switch so I wouldn't
> > be able to turn it off. Most of these car adapters draw some
> > current even with no load so I'll have to remember to reach
> > under the panel and pull the adapter or it will drain my battery.
> >
> > I think what I'll do is start off with the power outlet but
> > eventually transition to some sort of DC to DC converter like
> > one of these: http://www.powerstream.com/dda.htm
> >
> > It's a bit expensive at $30 but it's a nice package with
> > integrated mounting flanges making it easy to bolt to the
> > firewall. I tried using a 7805 and but was getting rather hot
> > to the touch with just the PDA attached. I was surprised but
> > when I looked up the specs I found that they're limited to
> > 400mA. That's right on the edge of what my PDA is drawing at
> > full bright.
> >
> > Thaks again for all the help.
> > -Luis
> >
> >
> >
> >
> > Read this topic online here:
> >
>
>
>
>
>
>
>
>
Message 11
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| Subject: | 5V Converter (Off Topic) do not archive |
Hey Nick,
You're understating the 7805's ability! You can easily draw 400mA from an
LM7805 with a small aluminum heatsink, say 2" sq. They're thermally
protected and nearly foolproof. I've never had one fail over the years and I
use them by the dozens in all kinds of supplies. They're all over my shop.
I power an iPaq 4350 and HX2715 all the time with them. If the PDA draws
less than a half amp a 7805 will work fine. If the PDA requires over an amp
(when the battery is dead or the display is cranked) then maybe another
device would be better.
Regards,
Ted
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Nick Scholtes
Sent: Monday, January 08, 2007 3:30 PM
Subject: Kitfox-List: 5V Converter (Off Topic)
Hi Guys,
My "real job" is being an electrical engineer, so if I "geek out" too much
here, just slap me.......
Regarding the topic of trickle charging through a cigarette lighter plug and
having to turn the Master on and off, there is a work-around. What you can
do is put a diode in parallel with the Master switch (anode connected to the
cigarette lighter, cathode to the inboard side of the Master switch). This
makes it so that when the Master switch is turned ON, current can flow
either into the system or out of the system. But, when the Master switch is
turned OFF, current can only flow INTO the system, hence you will only be
able to trickle-charge (current flowing
IN) when the Master is off, and if you left a load plugged into the
cigarette lighter the diode would prevent it from pulling current when the
Master is off. This would alleviate the need to do anything manually to
configure breakers or switches, which I know I'd forget to do
sometime........
Regarding using a 7805, here are some thoughts. It says on the datasheet
that the 7805 can output "up to" 1 Amp. But that isn't really the limiting
factor, the heat dissipation is. The TO-220 package (which is what the 7805
comes in) can reasonably dissipate about .75 watts if it is not heat-sinked,
and it can dissipate about 2 watts if it is heat-sinked really well (like
sitting at the bottom of Lake Michigan!) To calculate the wattage that it
dissipates, just take the voltage that is across it, and multiply by the
current through it (power = voltage * current). Since you've got a 12V
system and the 7805 outputs 5V, you've got 7V across the 7805 (more than
this really, because a 12V system typically runs between 12.8 and 13.3 or
so). So, to get .75 watts dissipated in the device, you can pull about 0.1
amps out of the device. As Luis stated, pulling 400 mA out of the device
will be dissipating 2.8 watts which will get it pretty darn hot without a
heatsink, and even with a very good heatsink it will still get pretty hot,
easily hot enough to burn you. Max junction temp is 125C, and 2.8 W
un-heat-sinked will get it up higher than that (on a hot day with a hot
ambient temperature). Realistically, a non-heat-sinked 7805 in a 12V system
will only be useful up to about 100 mA, which is useful for many things, but
not a PDA on full bright that draws 400 mA.
An alternative is an actual switching converter. You can get those at
various places like Digi-Key. I only spent a minute looking for one, but
here's one for about $15 or so, and I'm sure if you looked you could find
one quite a bit cheaper than that:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=296&M=PT78ST105H
A switching converter like this is better than 80% efficient, so only 20% of
the total power consumed is dissipated in the device. So your PDA draws 2 W
(5V*.4A), which means that the converter will only dissipate .5W, which it
can handle no-problem.
The comment about using multiple 7805 in parallel is definitely a practice
to be avoided. The problem here is that the 7805, being a power source,
has a low-impedance output. If you connect two low-impedance outputs
together, and if they are not exactly matched, one will put out just a tiny
bit higher voltage than the other, and since they are low impedance, the
high one will feed a huge amount of current to the low one. The only way to
realistically "load share" using two low-impedance outputs is to put a diode
in series with each output, but again this isn't a very good solution
because the output/diode combination that puts out the higher voltage will
end up doing all the work and it won't truly be "sharing".
Sorry for "geeking out" on you!
Best Regards,
Nick Scholtes
Time: 11:09:55 AM PST US
From: "Noel Loveys" <noelloveys@yahoo.ca>
Subject: RE: Kitfox-List: Re: Question for PDA GPS users: Hooking up power.
Correct you would have to leave the master and the power outlet breakers in
to trickle charge the battery...Max current 70% the amp value of the
breaker. Remember to pull the breakers on everything else.
The DC to DC adapters do consume a small (almost tiny) amount of current
even while under no load but that is why you have master switches and as I
recommend an accessory beaker between the power outlets and the main buss.
You could use several 7805 in parallel to attain the current you will need.
Keep a good heat sink on all of them. I used one on a converter I built for
a digital camera. I could get three pics before the circuit board got too
hot for my liking. The answer was to install a resistor in series with the
camera to reduce the load at the converter. I didn't mind waiting an extra
second or two for the camera to cycle. It's been working well for just
under ten years now.
Noel
> -----Original Message-----
> From: owner-kitfox-list-server@matronics.com
> [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of wingnut
> Sent: Sunday, January 07, 2007 11:24 AM
> To: kitfox-list@matronics.com
> Subject: Kitfox-List: Re: Question for PDA GPS users: Hooking up
> power.
>
>
>
> Thanks for all the help guys. I like the idea of being able to use
> the power outlet to trickle charge the main battery.
> There's one snag though; In order to do this, the power outlet would
> have to bypass the master switch so I wouldn't be able to turn it off.
> Most of these car adapters draw some current even with no load so I'll
> have to remember to reach under the panel and pull the adapter or it
> will drain my battery.
>
> I think what I'll do is start off with the power outlet but eventually
> transition to some sort of DC to DC converter like one of these:
> http://www.powerstream.com/dda.htm
>
> It's a bit expensive at $30 but it's a nice package with integrated
> mounting flanges making it easy to bolt to the firewall. I tried using
> a 7805 and but was getting rather hot to the touch with just the PDA
> attached. I was surprised but when I looked up the specs I found that
> they're limited to 400mA. That's right on the edge of what my PDA is
> drawing at full bright.
>
> Thaks again for all the help.
> -Luis
>
>
>
>
> Read this topic online here:
>
Message 12
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Thanks Don.
----- Original Message -----
From: Don Pearsall
To: kitfox-list@matronics.com
Sent: Sunday, January 07, 2007 4:27 PM
Subject: RE: Kitfox-List: Sportflight
Sportflight.com is coming back up slowly. I changed hosting companies
and the files do not transfer very smoothly. But I will keep working at
it.
Don Pearsall
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of jeff puls
Sent: Sunday, January 07, 2007 1:01 PM
To: kitfox-list@matronics.com
Subject: Kitfox-List: Sportflight
Sportflights web page has been down for several days. Anybody else try
it lately? Jeff
http://www.matronics.com/Navigator?Kitfox-Listhttp://forums.matronics.com
Message 13
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| Subject: | New Kitfox Videos |
OK I got more done the other day but I only got one put together.
http://www.cfisher.com/kitfox/ Jan 7 Kitfox Take offs.
The take off run is about 100 feet or so each time maybe +/- 20 feet.
What would it do if a swaped for a 914 ?
And how does this compare to others?
Dave
KF IV 582 GSC
Message 14
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| Subject: | Re: Norwegian Stalls |
At 02:28 PM 1/8/2007, you wrote:
>At the end of it, I have the stick to the most backward
>position, I feel the plane trembling, a wing or the other drops, which
>I correct with a bit of rudder and aileron, to keep the ball centered,
>then I can't get any slower because I sink now maybe 500 fpm. This is
>mushing down, right?
Yes. You can call it that.
>At that moment, the wings are partially stalled,
>right?
At least.
>And the elevator is not?
Usually no. (Flat spins excepted.)
>But why doesn't the nose drops then?
It does. The reason it doesn't drop straight down is because you've got the
stick in your lap, the horizontal stab is not stalled, so that when the
plane moves forward the tail is driven down and the nose up. Your mush may
seem to be at zero airspeed, but it's not. It is an equilibrium balance
between forward airspeed and the concomitant elevator effectiveness, and
the stall of the wings and their associated drop. If you ever achieved zero
airspeed, (say you pull nose high with no thrust,) you'll find the wings
fall through quite perpendicularly. I can't remember what the aerobatic
term for it is as the Decathlon I used wasn't allowed to back-slide at all.
My instructor would never let me achieve "zero" airspeed.
Guy
Message 15
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| Subject: | Re: New Kitfox Videos how do you post vid? |
In a message dated 1/8/2007 9:27:45 P.M. Central Standard Time,
dave@cfisher.com writes:
OK I got more done the other day but I only got one put together.
_http://www.cfisher.com/kitfox/_ (http://www.cfisher.com/kitfox/) Jan 7
Kitfox Take offs.
The take off run is about 100 feet or so each time maybe +/- 20 feet.
What would it do if a swaped for a 914 ?
And how does this compare to others?
Dave
KF IV 582 GSC
I watched your ski flying very carefully very cool.... I have a vid from
my short runway.... how did you post it? its on my computer... Dave
:-)
Message 16
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| Subject: | Re: Jabiru vs. Rotax. WAS: Rear spar attach reinforcement |
I've been tracking the same thing. Finally found hose that is leaking unde
r the ends. It does not leak until left overnight and then gets worse and
worse.=0A=0AJim Shumaker=0A=0A=0A----- Original Message ----=0AFrom: wingnu
t <wingnut@spamarrest.com>=0ATo: kitfox-list@matronics.com=0ASent: Sunday,
January 7, 2007 7:07:09 AM=0ASubject: Kitfox-List: Re: Jabiru vs. Rotax. WA
S: Rear spar attach reinforcement=0A=0A=0A--> Kitfox-List message posted by
: "wingnut" <wingnut@spamarrest.com>=0A=0AI've been trying to track down a
small coolant leak for the past couple of weeks that has me wishing for a J
abiru. I pull the cowling off as soon as I get in the hangar but can't see
anything. I come back the next morning and there's a small puddle. Driving
me nuts. I'm going to have to sleep under the darn thing to find this leak.
=0A=0A-Luis=0A-824KF=0A=0A=0A=0A=0ARead this topic online here:=0A=0Ahttp:/
/forums.matronics.com/viewtopic.php?p=86039#86039=0A=0A=0A=0A=0A=0A=0A=0A
=======================
Message 17
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| Subject: | Re: New Kitfox Videos |
In a message dated 1/8/2007 9:27:45 P.M. Central Standard Time,
dave@cfisher.com writes:
OK I got more done the other day but I only got one put together.
I have a cpl min of Vid but its over 300 megabite! it has a cple takeoffs
and landings....
Dave P
582
KF 2
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