Today's Message Index:
----------------------
1. 12:05 AM - Good website (Keith Burris)
2. 06:51 AM - Tube and Fabric Ground Plane (Jared Yates)
3. 07:53 AM - Re: "engineers" (Speedy11@aol.com)
4. 09:10 AM - Re: Switches (Robert L. Nuckolls, III)
5. 09:35 AM - Re: Re: Switches (Robert L. Nuckolls, III)
6. 09:53 AM - Re: Re: "engineers" (Robert L. Nuckolls, III)
7. 09:57 AM - Re: Good website (Robert L. Nuckolls, III)
8. 10:05 AM - Re: Tube and Fabric Ground Plane (Robert L. Nuckolls, III)
9. 11:41 AM - Slick Start For Sale (Barry)
10. 06:05 PM - Questions: 17-5 & Sizing (Perry, Phil)
11. 07:59 PM - Where is the missing atmospheric carbon dioxide? (RScott)
Message 1
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Folks;
Many of you probably know about these places but some may not. I found the
prices to be reasonable.
http://www.wiringproducts.com/index.html
Also, this place has some interesting products, especially for RVers. The
guy who runs it, Rich, is quite easy to work with
http://aircraftextras.com/
-- Keith
Message 2
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Subject: | Tube and Fabric Ground Plane |
Dear group,
I'm building a Bearhawk and would like to find the best way to mount the ELT
antenna, especially regarding the ground plane. I'm using the Ameriking 450
and the whip antenna that came with it. I can use the aluminum wing as a
ground plane for the VHF com, but I was thinking that it would be better to
keep the ELT antenna on the fuselage. This would allow me to reduce the
length of the wire run and thus reduce the chances of crash damage. It
would also allow me to provide enough distance between the com and ELT to
prevent resonance on the emergency frequency.
Some builders have mounted the antenna inside of the 4130 tube fuselage,
which has the best crash resistance; but, I would think that the fuselage
would be a great faraday cage and would thus limit the transmission
considerably.
For these reasons I'd prefer to mount the antenna on the top of the fuselage
behind the cabin. In this particular fuselage there are non-structural
stringers that protrude about 3 inches above the primary structure, so I was
planning to make a bracket to use as a mount for the antenna. The bracket
would be shaped like an upside down U with the top of the bracket even with
the top of the stringers, so that the antenna would attach at the top of the
bracket and the bottom legs would be welded to either side of a crossing
tube. How should I provide for a ground plane? The stringers are aluminum
and about 12 inches apart, and the steel fuselage is about 3" below the base
of the antenna. Would it be a good idea to use either of those as part or
all of the ground plane, or would it be better to make something out of
copper foil and try to insulate that ground plane from the airframe parts?
Any thoughts?
Here's a picture of how the fuselage is built:
http://jaredyates.com/temp/groundplane.jpg
Thanks
Message 3
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So, Ralph.
It's okay for you to post unrelated remarks, but now (because you said so)
nobody else should respond.
Hmmm ... you got your shot in, but nobody can counter.
I suggest responding with "do not archive" is more appropriate. In fact,
such an addition may have been appropriate for your posting.
Stan Sutterfield
Do not archive
OK, this is not the correct venue to discuss this sort of thing. I'm the
biggest complainer of abuse of this email list and now I'm guilty. Please
don't reply to the list about this thread...if you want to continue we'll
find another venue.
Message 4
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At 06:01 PM 12/27/2009, you wrote:
>
>Thanks Bob; I guess I knew but forgot the points you made, should have known
>better. I see what I want around but it's made for heavy iron and cost like
>it also.
Yeah. I've participated in the design of a number
of specialized cockpit controls for things like
gear, flaps, spoilers, etc. In addition to their
unique form and fit requirements to comply with
design goals for cockpit decorum, they often
included a variety of position sensors with redundancy
to preclude un-commanded motions, etc.
I think the last flap control handle project I
saw produced a device that sold to the OEM for
about $2,000!
Here in the OBAM aircraft world, we can do a lot
to dress up plain vanilla controls. But the
Big Guys do it too. The gear and flap switches
in a Bonanza are Honeywell toggle switches with
added window dressing.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 5
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At 06:57 PM 12/27/2009, you wrote:
OK! Shot down by the master! I respect Bob's arguments; however, I
do not consider a $20 Mil-Spec switch to be a super-part. Certainly
we can use commercial grade switches in our homebuilt aircraft, but
it is still prudent to insure that the switches have undergone some
reliability testing and have current and voltage ratings appropriate
for their intended use. Certification by a nationally recognized
testing agency such as Underwriters Laboratories may add to the
switches cost a bit, but the rating confirms that required overload
and endurance testing have been successfully completed.
Are we shooting at each other or trying to achieve a
shared understanding? How does one conduct such
pre-purchase studies? I'm fairly certain that
every manufacturer did some pre-production proof
of design testing to insure compliance with their
own design goals. But few if any have published
reports on such studies unless they're attempting
to compete with other manufacturers where the
rules of the game call out Mil-Spec, SAE, ISO,
UL, etc. etc. I'll suggest that there are many
sources of switches suited to our tasks that offer
no published test data. Further, when data is
available, it was not gathered by the same test
protocols as competing products. I went through
this exercise 20+ years ago on the GP-180 program
at Gates-Learjet. Attempts to evaluate 6 different
brands of interchangeable basic switches based on
their published data proved impossible. But in
fact, every device being considered would have
been just fine for our application.
I would invite you to review a paper I wrote some
years ago about switch ratings at:
http://www.aeroelectric.com/articles/Switch_Ratings.pdf
Switch "ratings" are not a common language among
all manufacturers of switches . . . else there
would not be so many ratings standards by which
the folks who write rules for aforementioned games
can choose. Further, the ratings games are crafted
with the revenue generating applications (down time
on a $high$ machine costs many times more than the
value of the switch), safety issues in both industrial
and military hardware (switch failure increases risk
of injury or death).
In the OBAM aircraft environment, we assume risks
of for lack of knowledge and craftsmanship that are
generally considered to be very low numbers in the
commercial, industrial and military worlds. Hence
my vociferous suggestions that we place failure
tolerance above all other considerations for the
design, operation and maintenance of our airplanes.
A search of the accident archives reveals that
failures of electrical system components in light
aircraft account for a tiny proportion of causation
for the accident. In those situations where electrical
failures were prominent players, it was easy to deduce
in hindsight how that stack-up of events could have
been comfortably managed by the failure tolerant
aircraft flown by a knowledgeable pilot. I don't
recall reading ANY accident analysis where failure
of a component to perform as advertised was a
contributing factor. No doubt there are SOME such
reports but I've not found one yet.
It's been my suggestion for years of participation
first on Compuserve AVSIG and later here on the
Matronics Lists that we can design, fabricate
and operate airplanes using the most ordinary components
and still enjoy very low risk use of the airplane's
electrical system. This is especially true of machines
that get on average, 50 hours of service per year
as opposed to machines that run 1000's of hours
per year.
Bob . . .
Message 6
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OK, this is not the correct venue to discuss this sort of thing. I'm the
biggest complainer of abuse of this email list and now I'm guilty. Please
don't reply to the list about this thread...if you want to continue we'll
find another venue . . .
Is this not a venue for the exchange of simple-ideas
and their incorporation into recipes for success?
When an idea/recipe is offered, is it not useful to
gage potential quality of the idea against the demonstrated
history of the offerer?
While few of us here on the List have credentials framed
on our walls, we ALL have experiences and talents that
qualify us as teachers. Depending on the sum total of
life experiences and demonstrated achievements, some of us
have more to offer than others. But no combination of
simple-ideas into any recipe for success becomes less
valuable just because the offerer "is not qualified"
based on some arbitrary standard.
An argument was proposed that lack of recognized credential
placed the value of ideas or the integrity/motivations
of some offerers in doubt. I'll suggest that comparative study
of demonstrable achievement versus credential-based stature
in this community is useful to the goals of this List.
Bob . . .
Message 7
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Subject: | Re: Good website |
At 02:03 AM 12/28/2009, you wrote:
>Folks;
>Many of you probably know about these places but some may not. I
>found the prices to be reasonable.
>
><http://www.wiringproducts.com/index.html>http://www.wiringproducts.com/index.html
An impressive site . . . with caution. Terminals offered
are not PIDG style and there are good reasons to avoid glass
cartridge fuses. No doubt there are numerous products offered
that are useful to the OBAM aircraft builder but if
in doubt, ask about a product being considered here on
the List first . . .
Bob . . .
Message 8
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Subject: | Re: Tube and Fabric Ground Plane |
At 08:31 AM 12/28/2009, you wrote:
>
>
>Some builders have mounted the antenna inside of the 4130 tube fuselage,
>which has the best crash resistance; but, I would think that the fuselage
>would be a great faraday cage and would thus limit the transmission
>considerably.
Yes. Don't do this . . .
>For these reasons I'd prefer to mount the antenna on the top of the fuselage
>behind the cabin. In this particular fuselage there are non-structural
>stringers that protrude about 3 inches above the primary structure, so I was
>planning to make a bracket to use as a mount for the antenna. The bracket
>would be shaped like an upside down U with the top of the bracket even with
>the top of the stringers, so that the antenna would attach at the top of the
>bracket and the bottom legs would be welded to either side of a crossing
>tube. How should I provide for a ground plane?
Make sure you have good electrical connection to the bracket
that is welded to the tube. This can be accomplished by mate
up pressures of attaching hardware even when intermediate layers
include insulating materials.
> The stringers are aluminum
>and about 12 inches apart, and the steel fuselage is about 3" below the base
>of the antenna. Would it be a good idea to use either of those as part or
>all of the ground plane, or would it be better to make something out of
>copper foil and try to insulate that ground plane from the airframe parts?
>Any thoughts?
Foil ground plane strips on the inside of the fabric
would be useful but probably wouldn't increase
performance greatly. The BIG design problem is
one of mechanical robustness. Getting your antenna
mounted to solid structure through your proposed
bracket will go a long way toward a low maintenance
and adequately performing system. Of course the feedline
shield needs to get a good electrical connnection to
the same bracket.
Bob . . .
Message 9
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Subject: | Slick Start For Sale |
Slick Start p/n SS1001 removed at 160hr total time in good working condition to
install elecrtonic ignition. I have the installation instructions, STC info and
yellow tag return to service. $295.00 with shipping included. Contact me direct.
Do not archive. Thanks Barry
blalmarz@embarqmail.com
239-567-2271
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=279012#279012
Message 10
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Subject: | Questions: 17-5 & Sizing |
Hi,
I've been a lurker for awhile, mainly because I haven't had to think too
much about the electrical system of the airplane yet. There is no doubt
that I'll be covering some well plowed ground with these questions, but
maybe you can help get me off high-center.
I am building an all glass RV-10 and I don't plan on using Electronic
Ignition.
My first question involves figure 17-5 (Dual Alternator, Dual Battery
Electrical System). The narrative discussion on the crossfeed contactor
is a little light and I'm having a hard time getting a handle on that
diagram.
1) I'd like to understand how the cross feed functions.
a. Is it an automatic switch?
b. Is it closed during normal operations?
c. I'm guessing it's just like any other contactor and requires ~1
Amp current to maintain closure?
2) Still on 17-5, couldn't there be a diode placed between the
"Main Battery" and the "Main Bus"? For the cost of a diode, you could
add a secondary path that is independent of any contactor. The chances
of needing to use it is highly unlikely, but it's a really cheap way to
save 2-3 Amps (Main Bat Contactor, Aux Bat Contactor, Cross Feed
Contactor) if you ever need to shed off load.
3) Finally I'm not finding much in the way component sizing.
Meaning I'm trying to figure out which specific diodes I will need.
Which specific model numbers/sizes of contactors I will need.
Thanks for the help.
As I get the architecture laid out, I'll share it for review.
Thanks,
Phil
Message 11
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Subject: | Where is the missing atmospheric carbon dioxide? |
The models say it should be there, but it's not! We've gotta find
it--our models are right, because they all agree!
http://www.reuters.com/article/idUSTRE50S6CW20090129
http://www.icsu-visioning.org/2009/07/where-is-the-missing-atmospheric-carbon-dioxide/
Oh, but the way, the satellite failed--I don't know if the missile
crashed or if the satellite just didn't work. The Canadians built one
for .01% of our cost.
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