Today's Message Index:
----------------------
1. 12:03 AM - Re: Avionics Stack - Single Point Grounding... (Mickey Coggins)
2. 04:30 AM - Re: Avionics Stack - Single Point Grounding... (FLYaDIVE@aol.com)
3. 08:37 AM - Software in the cockpit (Ernest Christley)
4. 09:32 AM - Re: Software in the cockpit (FLYaDIVE@aol.com)
5. 10:05 AM - Re: Software in the cockpit (Charlie Kuss)
6. 10:05 AM - Re: Avionics Stack - Single Point Grounding... (Nancy Ghertner)
7. 01:09 PM - Wire sizes (lee.logan@gulfstream.com)
8. 02:19 PM - Re: Avionics Stack - Single Point Grounding... (Brian Lloyd)
9. 02:43 PM - Re: Wire sizes (Robert Sultzbach)
10. 03:33 PM - Re: Software in the cockpit (Brian Lloyd)
11. 05:27 PM - Intercom CAD file wanted (Charlie Kuss)
12. 05:27 PM - Re: Wire sizes (Bret Smith)
13. 05:52 PM - Re: Software in the cockpit (Matt Prather)
14. 06:37 PM - Re: Software in the cockpit (Malcolm Thomson)
15. 06:51 PM - Re: Wire sizes (LarryRobertHelming)
16. 11:23 PM - Re: Avionics Stack - Single Point Grounding... (Mickey Coggins)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Avionics Stack - Single Point Grounding... |
--> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch>
> The avionics trays should be grounded. If they are in an aluminum
> airplane with an aluminum instrument panel and the panel is bolted or
> riveted to the airframe somehow, your job is done. If you have some sort
> of nonconducting panel such that the avionics trays are insulated from
> the rest of the airframe, run a wire from your avionics tray(s) to your
> single-point ground.
>
> And this has nothing to do with the power ground for the radios. Each
> radio has a ground or multiple ground pins on its connector. These
> should be connected to your single point ground independently of the
> chassis ground.
My intercom (Flightcom 403) has a ground pin and the case is grounded,
and there is continuity between the two. I have not tested any of my
other avionics. I wonder if this is common, or will cause a problem.
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Avionics Stack - Single Point Grounding... |
--> AeroElectric-List message posted by: FLYaDIVE@aol.com
In a message dated 6/27/06 3:09:01 AM Eastern Daylight Time,
mick-matronics@rv8.ch writes:
> My intercom (Flightcom 403) has a ground pin and the case is grounded,
> and there is continuity between the two. I have not tested any of my
> other avionics. I wonder if this is common, or will cause a problem.
>
> --
> Mickey Coggins
> http://www.rv8.ch/
> #82007 finishing
===================
Mickey:
This depends on if it is an Audio Ground or a Power Ground.
Barry
"Chop'd Liver"
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Software in the cockpit |
--> AeroElectric-List message posted by: Ernest Christley <echristley@nc.rr.com>
AeroElectric-List Digest Server wrote:
________________________________ Message 24 ____________________________________
Time: 06:25:55 PM PST US
--> AeroElectric-List message posted by: "Alex Peterson" <alexpeterson@earthlink.net>
>> Pilots who *think* they understand computers will trust their
>> lives to them, and pilots who truly *do* understand computers
>> will not.
>
>
>Except for those pilots driving cars less than about twenty years old to the
>airport, and who may pull out in front of another car, trusting that the
>car's computer will keep shoving gas and spark in!
That is an insiduous mistake, Alex.
A) My car has mechanically actuated brakes.
B) I expect the other car to have mechanically actuated brakes.
C) I am able to validate the health of the onboard computer in a very low-risk
environment before performing the high-risk maneuver. The engine is running while
sitting at the stop light, after all.
D) I 'trust' that the engine computer's software is not built on top of a hacked
version of DOS3.1 with three different graphic libraries, a widget library,
a tftp server, a TCP-IP stack, a general purpose command line interpreter, a Java
byte-code interpreter and Perl. Think I sound ridiculous. I've worked on
embedded systems built this way.
E) Car makers have huge engineering staffs with salaries amortized over thousands
if not millions of units. Staffs that are paid well to do the boring and tedious
jobs of software validation. This job is boring, thankless (nobody likes
the guy that says the software doesn't work), and sucks in general. I wouldn't
do it if it didn't allow me to buy so many airplane parts.
The point is, software ain't software ain't software, anymore than bolts is bolts
is bolts. People who would faint at the idea of using a course thread bolt
from the BigBox Hardware store will happily throw a mission critical box in their
panel without a thought. Well, actually there is a thought. The thought
is, "Those software guys are all so smart. Just look at what Bill Gates and
Steve Jobs did in their garages. This new SuperEFIS is all bright and shiny,
with cool graphics and lots of buttons, and if it breaks it will phone home through
a satellite connection to the Internet and update itself. It's going to
make my flying so easy." That thought should receive the same esteem that would
be received from the guy walking down the bolt section at Lowe's going, "Ooh!
Shiny stuff."
Someone asked me if I were endorsing Dynon over BMA. I'm not; though, my current
plan is to purchase a Dynon unit. I'm endorsing a set of criteria to choosing
what software goes in your cockpit. When evaluating a unit, conisider these
questions:
1) Does the level of glitz and functionality correlate with the size of the company
and the number of units they expect to sell? There is no free lunch. Software
has to be validated, and that's expensive, because it is boring, tedious
and no one wants to do it. If the company has three employees, and the unit
has more functionality that a Garmin396 at 1/2 the price....you'll probably be
a beta tester.
2) Do you get the feeling that the software would be useless without the hardware,
or is this something ported from a PC game? General purpose software is just
that 'general purpose'. Lots of compromises and obfuscations are made on
the way from here to there. The idea that the software is tied to the hardware
will mean that the software knows the limits of the hardware and can check that
data recieved from the hardware is not out of bounds. The more 'stuff' that
is inserted between the hardware and the decision making portion of the software,
the more chances there are for things to screw up and the more time the
processor spends bookeeping data that has nothing to do with showing you which
way is up. Nothing is more fun in a development organization that watching
the software side saying a problem is a hardware issue, while the hardware guys
say that a software fix is needed. Those issues occur less and less the closer
the two are tied together.
3) How often are updates released? 'Update' is an interesting word in the software
field. An update used to mean additional code to add functionality for a
changing world. It has slowly been morphed by companies not wanting to admit
that they have sold you crap-in-a-box. It now means "a self-administered field
repair". If your looking at a car that has a history of needing a repair once
a month, would you drive off the lot with it? And yet you would call that
a 'feature' in a piece of software? A piece of software that you expect to tell
you which way is up when you can't see the ground? An EFIS, or any other
embedded software, doesn't live in a changing world. It is spec'd to tell up
from down. Up is up and down is down. Until those change, an update isn't.
It's a field repair.
4) Are the company representatives 'excited' about new technologies? You can leave
this one off if you'd like. It's my bias showing. My experience is that
older engineers tend to view new software 'methodologies' with a critical eye.
The younger guys tend to jump on the latest software fad with exuberence, generally
breaking things that were working and needing more hardware horsepower
to do boot. I've watched myself get less exuberant and more critical as the
years have passed. A representative that is ready to jump in an unproven software
technology without careful consideration of the cost/benefit equation is
a red flag for me. The experienced guys know that it is the same ol' stuff,
with a different set of headaches.
I'm not trying to steer anyone away or to a particular unit. I'm just saying that
the software in the cockpit deserves the same amount of consideration as any
other piece of the airplane.
Bob K, I'm going to vehemently disagree with the assertion that we can build a
simple autopilot and have it controlled by PocketPC type device that we would
not rely on. Humans don't work that way. Once it is discovered that the PocketPC
will fly the plane just dandy on a smooth air day, we start to trust it.
Still works in minor turbulence, we trust it a little more. We take it into
IMC and it starts to get the leans...unfortunately, we trust it as it flies us
into cumulous granite. Do not put any software in control of your airplane unless
you trust it completely from the outset. I'm not saying a autopilot should
not be done, I'm saying that software that can not be fully validated should
not be considered.
--
,|"|"|, Ernest Christley |
----===<{{(oQo)}}>===---- Dyke Delta Builder |
o| d |o http://ernest.isa-geek.org |
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Software in the cockpit |
In a message dated 6/27/2006 11:41:14 AM Eastern Standard Time,
echristley@nc.rr.com writes:
A) My car has mechanically actuated brakes.
B) I expect the other car to have mechanically actuated brakes.
C) I am able to validate the health of the onboard computer in a very
low-risk environment before performing the high-risk maneuver. The engine is
running while sitting at the stop light, after all.
D) I 'trust' that the engine computer's software is not built on top of a
hacked version of DOS3.1 with three different graphic libraries, a widget
library, a tftp server, a TCP-IP stack, a general purpose command line
interpreter, a Java byte-code interpreter and Perl. Think I sound ridiculous.
I've
worked on embedded systems built this way.
E) Car makers have huge engineering staffs with salaries amortized over
thousands if not millions of units. Staffs that are paid well to do the boring
and tedious jobs of software validation
=================================================
Ernest:
O! Boy! Are you misinformed ....
A - Does your car have an ABS breaking system?
Then they are computer controlled.
A - Again ... When you take your foot off the gas and slam on the break what
do you thing tries to keep the engine from stalling? Brakes talking to the
computer and then computer talking to the engine.
B - The ENTIRE action of the car should be actuated by the BRAIN way before
the key hits Start. But obviously that is not happening. As for TRUSTING in
other people or their cars... Poor - Bad Idea.
C - WHY the HELL are you doing a "high-risk maneuver"?
I fly formation, I get close to my #1 BUT the scariest thing I ever do is
driving. I KNOW what my #1 is going to do. I have no freeken idea what the
other drivers around me are going to do of even if they are SOBER! Just
consider your posted response!
D - I must agree with your 'D' statement. So why is Bill Gates the richest
man in the world? He should be sued!
E - As for your 'E' statement ... I guess you never heard of Mandatory
Government Recall on cars.
Five items are enough to think about.
Barry
"Chop'd Liver"
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Software in the cockpit |
--> AeroElectric-List message posted by: Charlie Kuss <chaztuna@adelphia.net>
>Snipped
>Ernest:
>
>O! Boy! Are you misinformed ....
>
>A - Does your car have an ABS breaking system?
>Then they are computer controlled.
>
>A - Again ... When you take your foot off the gas and slam on the
>break what do you thing tries to keep the engine from
>stalling? Brakes talking to the computer and then computer talking
>to the engine.
>
>snipped
>
>Barry
>"Chop'd Liver"
Barry,
You are "almost" correct here. The ABS system has it's own
computer. Upon starting the engine, the computer does a diagnostic
test of all parts of the system. If everything is OK , the ABS light
on the instrument panel will extinguish after 5-10 seconds. The
system will then operate normally. IF there is a problem, the ABS
light stays on and the system disables itself. This is the failsafe
mode. You now have ab circa 1966 to 1980s brake system.
Charlie Kuss
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Avionics Stack - Single Point Grounding... |
--> AeroElectric-List message posted by: Nancy Ghertner <nghertner@verizon.net>
On 6/26/06 7:34 PM, "Doug Windhorn" <N1DeltaWhiskey@comcast.net> wrote:
> Disagree, to a point. Positive should be connected before ground when we are
> talking about energy sources (say battery). Why? To prevent a short circuit.
> If the ground is connected first, any contact by the positive lead will send
> sparks flying. If the positive is connected first, one will be attaching the
> wire to a system generally at ground potential.
>
> This goes to the point missing from the comments below. Namely that electrons
> move only when invited to do so, either when being sucked by a higher voltage
> potential, or when being pushed around by electromagnetic fields (going to
> stop there before revealing my ignorance about chemical reactions, but think
> the voltage potential is the driving force there). Connecting the ground
> first will provide a complete circuit path if the positive terminal is shorted
> against the grounded environment generally present in the airframe
> environment. Connecting the positive first will only result in a ground
> coming in contacted with an intended grounded airframe at the same potential,
> hence negligible, if any, sparks will fly.
>
> For energy loads (consumers), it really does not, usually, make much
> difference electrically, though it could mechanically (don't have a specific
> instance, just leaving the door open to avoid rebuttal on the point).
> Besides, you have deenergized the potential circuit before doing this - right?
>
> Doug Windhorn
> ----- Original Message -----
> From: John W. Cox
> To: aeroelectric-list@matronics.com
> Sent: Monday, 26 June, 2006 8:40
> Subject: RE: AeroElectric-List: Avionics Stack - Single Point Grounding...
>
>
> I am no EE but in A & P school they were quite clear that electrons come from
> the negative terminal. That is why the positive is always connected first and
> the negative terminal is connected last. The better the negative (Ground)
> path - "Path of least resistance" .. I know a straight line between two
> points. The electrons will always chose the lazy way. Still an important
> idea for high quality ground connections.
>
>
>
> John Cox - $00.02
>
>
>
>
> ------------------------------------------------------------------------------
>
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
> Fiveonepw@aol.com
> Sent: Monday, June 26, 2006 6:40 AM
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Avionics Stack - Single Point Grounding...
>
>
>
> In a message dated 6/26/06 7:09:07 AM Central Daylight Time,
> don.honabach@pcperfect.com writes:
>
>
>
>
> I'm trying to wrap my mind around the single-point grounding system as
> described in the 'Connection, in particular as it affects devices in the
> avionics stack.
>
>
>
>>>>>
>
> Some EE out there will undoubtedly correct me, but this is how I look at it:
>
> Electrons come screaming out of the battery up an interstate highway of copper
> wire to each device. Once being tortured therein, they must return to the
> fold (battery). Given the choice of a return Interstate highway of more
> copper, or "over the river & thru the woods (device chassis, screws, metal
> mashed to other metal etc.- just think HIGHER RESISTANCE than the highway)
> they will prefer the easier route- one that is just as easy going as coming.
> When all electrons travel this way, they are happy electrons and are less
> likely to insidiously attack your ears as noyz! 8-)
>
> (and yeah, I know about "holes" but let's KIS)
>
> Mark - purty darn quiet Z-11 RV-6A
> do not archive unless this adds something to the discussion or I case I'm just
> plain wrong!
>
I agree with Doug but I don't care which way electrons flow, since I don't
understand them anyway. Always connect the positive first with your car,
right? I have seen many people weld their rings to their fingers; and as
Mick Jagger once said: "and it hurts baby."
Lory Ghertner
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: lee.logan@gulfstream.com
Oldest question in the book and perhaps heresy on this site, but here goes
anyway: Greg Richter "Aircraft Wiring for Smart People" recommends 18 and
22 guage wire for nearly all requirements but presupposes a 24 volt system
per his recommendations. I'm at work and looking to order some of the wire
for the next steps in my project and don't know what the equivalents would
be in a 12 volt system. Do I step up one size or two or is there some
other formula that applies? I have The Aeroelectric Connection at the
hangar but I need to order some of this from here at work. Any help?
Lee...
Lee Logan
Government Programs and Sales Support
Gulfstream Aerospace Corporation
Savannah, Georgia
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
This e-mail message, including all attachments, is for the sole use of the
intended recipient(s) and may contain legally privileged and confidential
information. If you are not an intended recipient, you are hereby notified
that you have either received this message in error or through
interception, and that any review, use, distribution, copying or disclosure
of this message or its attachments is strictly prohibited and is subject to
criminal and civil penalties. All personal messages express solely the
senders views and not those of Gulfstream Aerospace Corporation. If you
received this message in error, please contact the sender by reply e-mail
and destroy all copies of the original message.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Avionics Stack - Single Point Grounding... |
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
On Jun 27, 2006, at 2:56 AM, Mickey Coggins wrote:
> --> AeroElectric-List message posted by: Mickey Coggins <mick-
> matronics@rv8.ch>
>
>> The avionics trays should be grounded. If they are in an aluminum
>> airplane with an aluminum instrument panel and the panel is bolted
>> or riveted to the airframe somehow, your job is done. If you have
>> some sort of nonconducting panel such that the avionics trays are
>> insulated from the rest of the airframe, run a wire from your
>> avionics tray(s) to your single-point ground.
>> And this has nothing to do with the power ground for the radios.
>> Each radio has a ground or multiple ground pins on its connector.
>> These should be connected to your single point ground
>> independently of the chassis ground.
>
> My intercom (Flightcom 403) has a ground pin and the case is grounded,
> and there is continuity between the two. I have not tested any of my
> other avionics. I wonder if this is common, or will cause a problem.
It will not cause a problem. The manufacturer designed it that way.
Some devices may show a low resistance between case and ground pin
(on the order of 10 ohms or so). They use a 10 ohm resistor to get
the shielding while the resistance greatly reduces the current in any
potential ground loop.
The bottom line is that, if it has a metal case the manufacturer
expects the case to ground to the airframe through the panel, or at
least there is a very good chance that it will. If they don't want
the case grounded you will find something about that in the
documentation and they will provide the wherewithal to insulate the
case.
Brian Lloyd 361 Catterline Way
brian-yak AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: Robert Sultzbach <endspeed@yahoo.com>
Hi Lee,
Just figure out the amperage load the wire is going
to have to carry and check the distance it has to
carry it. Then check Vans construction manual. On
the last page in the section called Electrical Wiring
Notes there is a wire length versus wire size for any
amperage carried figure that will answer your
question.
Bob
--- lee.logan@gulfstream.com wrote:
> --> AeroElectric-List message posted by:
> lee.logan@gulfstream.com
>
> Oldest question in the book and perhaps heresy on
> this site, but here goes
> anyway: Greg Richter "Aircraft Wiring for Smart
> People" recommends 18 and
> 22 guage wire for nearly all requirements but
> presupposes a 24 volt system
> per his recommendations. I'm at work and looking to
> order some of the wire
> for the next steps in my project and don't know what
> the equivalents would
> be in a 12 volt system. Do I step up one size or
> two or is there some
> other formula that applies? I have The Aeroelectric
> Connection at the
> hangar but I need to order some of this from here at
> work. Any help?
>
> Lee...
>
> Lee Logan
> Government Programs and Sales Support
> Gulfstream Aerospace Corporation
> Savannah, Georgia
>
>
>
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> This e-mail message, including all attachments, is
> for the sole use of the
> intended recipient(s) and may contain legally
> privileged and confidential
> information. If you are not an intended recipient,
> you are hereby notified
> that you have either received this message in error
> or through
> interception, and that any review, use,
> distribution, copying or disclosure
> of this message or its attachments is strictly
> prohibited and is subject to
> criminal and civil penalties. All personal messages
> express solely the
> senders views and not those of Gulfstream
> Aerospace Corporation. If you
> received this message in error, please contact the
> sender by reply e-mail
> and destroy all copies of the original message.
>
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>
>
>
>
> browse
> Subscriptions page,
> FAQ,
> http://www.matronics.com/Navigator?AeroElectric-List
>
>
> Admin.
>
>
>
>
>
>
>
>
>
>
>
__________________________________________________
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Software in the cockpit |
On Jun 27, 2006, at 12:07 PM, FLYaDIVE@aol.com wrote:
> In a message dated 6/27/2006 11:41:14 AM Eastern Standard Time,
> echristley@nc.rr.com writes:
> A) My car has mechanically actuated brakes.
>
> B) I expect the other car to have mechanically actuated brakes.
>
> C) I am able to validate the health of the onboard computer in a
> very low-risk environment before performing the high-risk
> maneuver. The engine is running while sitting at the stop light,
> after all.
>
> D) I 'trust' that the engine computer's software is not built on
> top of a hacked version of DOS3.1 with three different graphic
> libraries, a widget library, a tftp server, a TCP-IP stack, a
> general purpose command line interpreter, a Java byte-code
> interpreter and Perl. Think I sound ridiculous. I've worked on
> embedded systems built this way.
>
> E) Car makers have huge engineering staffs with salaries amortized
> over thousands if not millions of units. Staffs that are paid well
> to do the boring and tedious jobs of software validation
> ========================
=========================
> Ernest:
>
> O! Boy! Are you misinformed ....''
Well, I don't really think he is. I actually think his point is well
taken. I also think that the two of you are approaching this subject
orthogonally and not really talking about the same thing.
Ernest's points about mission-critical applications (and a PFD is a
mission-critical application in my book) are well taken. There are
ways to develop software so as to make it more reliable and less
prone to undesired interactions between modules. One of the more
successful is to ensure that the software is simple enough that you
know all the inputs, all the outputs, and all the possible paths
through the code. This makes testing a closed-ended process. If you
want a new feature, find a way to isolate it from what you already
have so that you minimize any possible interaction. Putting it in a
separate box with tight controls over what gets in our out is not a
bad idea.
OTOH, Microsoft bases their development on the proliferation of new
features, not on ensuring that the existing features are without
error. In fact, Microsoft "fixes" software by layering more software
on top to mitigate the behavior of underlying software. (I have been
wracking my brain to think of a good mechanical analogy but I can't
come up with one because mechanical things just aren't made this
way.) It is a pretty scary process that precludes Microsoft from
being used in mission-critical applications. OTOH, it is great if you
want shiny new flashinlitez every few months.
Should we shoot/sue Bill Gates? No. He is making the product that
people seem to want. They want features more than they want
reliability. Would I fly behind any box that has a Microsoft product
running in it? Not on your life.
Now on to the point about things like ABS and computerized engine
controls. The interesting thing about these two functions is that
they are very well defined functions. The automotive industry also
puts them in separate boxes so there is as little interaction between
them as possible. But software is complex and sometimes errors do get
through and need to be dealt with. Yes, there are recalls that
require new code or new boxes to be installed. But if you compare the
rate of that to the rate of updates to Windows, you will see several
orders of magnitude difference. The automotive code is simpler and
better tested. Odds are very good it is right. The odds that
Microsoft will issue new, bug-free code is about as close to zero as
you can get.
They are different markets.
Now getting back to aviation. People selling low-cost PFDs (that is
what we are talking about when we talk about attitude, heading,
altitude, and airspeed) face the same problem as Bill Gates. You, the
buyer, want as many features as you can get for your dollar. You want
it to do all that and be an engine monitor and moving map too. I am
with Ernest on this. I want that box to do only what it is supposed
to do and have the manufacturer spend a LOT of time ensuring that it
does this one, relatively straight-forward feature set flawlessly.
You want an engine monitor? Put in another box dedicated to that
function. Keep the functions isolated so one can't hose-up the other.
Want an example of why this is good? Ask computer geeks who went to
MIT in the '70s about a critical mainframe that would crash every 28
days. Someone even figured out that it occurred at precisely the
moment when the phase of the moon changed. (I forget whether it was
new moon or full moon.) Can you imagine the consternation of the
technical staff to learn that their computer was going to crash
whenever the moon was full? Shades of the Wolfman!
It took months to find the problem. The problem turned out to be a
simple little throw-away feature that someone hacked into the real-
time clock function of the machine. All the feature did was calculate
the phase of the moon. It wasn't documented. It was so simple. It was
probably the work of a bored programmer late some night. It is just
that the programmer allocated one byte too little for one variable
and the software wrote off the end of the variable into someone
else's memory causing the operating system to crash. Unfortunately it
took things like student registration and payroll with it when it died.
So when you build something on top of something someone else has
built you inherit all their bugs into your system. Better to simplify
and compartmentalize.
Brian Lloyd 361 Catterline Way
brian-yak AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
=97 Antoine de Saint-Exup=E9ry
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Intercom CAD file wanted |
--> AeroElectric-List message posted by: Charlie Kuss <chaztuna@adelphia.net>
Listers,
I'm wiring up my Flightcom 403d intercom on my RV-8A project. I'd
like to thank Pete Howell for his tips on adding additional aux
inputs to this intercom. I called Flightcom's tech support earlier
today. I asked if they had a CAD drawing of the wiring schematic
(exterior wiring) of this intercom. I was hoping that I could start
with their generic drawing and modify it to show my system.
Unfortunately, the tech looked on their server but couldn't find a
CAD based drawing.
Does anyone have a CAD file of their intercom that they would be
willing to share? I'd be happy to trade CAD schematics, as I've
already diagrammed most of the circuits on my 8A.
Charlie Kuss
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Bret Smith" <smithhb@tds.net>
This should help... http://www.aeroelectric.com/CH_8/Ch8_R12.pdf
Bret Smith
RV-9A (91314)
Mineral Bluff, GA
www.FlightInnovations.com
-----Original Message-----
Sent: Tuesday, June 27, 2006 5:38 PM
--> AeroElectric-List message posted by: Robert Sultzbach
--> <endspeed@yahoo.com>
Hi Lee,
Just figure out the amperage load the wire is going to have to carry and check
the distance it has to carry it. Then check Vans construction manual. On the
last page in the section called Electrical Wiring Notes there is a wire length
versus wire size for any amperage carried figure that will answer your question.
Bob
--- lee.logan@gulfstream.com wrote:
> --> AeroElectric-List message posted by:
> lee.logan@gulfstream.com
>
> Oldest question in the book and perhaps heresy on this site, but here
> goes
> anyway: Greg Richter "Aircraft Wiring for Smart People" recommends 18
> and
> 22 guage wire for nearly all requirements but presupposes a 24 volt
> system per his recommendations. I'm at work and looking to order some
> of the wire for the next steps in my project and don't know what the
> equivalents would be in a 12 volt system. Do I step up one size or
> two or is there some other formula that applies? I have The
> Aeroelectric Connection at the hangar but I need to order some of this
> from here at work. Any help?
>
> Lee...
>
> Lee Logan
> Government Programs and Sales Support
> Gulfstream Aerospace Corporation
> Savannah, Georgia
>
>
>
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> This e-mail message, including all attachments, is for the sole use of
> the intended recipient(s) and may contain legally privileged and
> confidential information. If you are not an intended recipient, you
> are hereby notified that you have either received this message in
> error or through interception, and that any review, use, distribution,
> copying or disclosure of this message or its attachments is strictly
> prohibited and is subject to criminal and civil penalties. All
> personal messages express solely the senders views and not those of
> Gulfstream Aerospace Corporation. If you received this message in
> error, please contact the sender by reply e-mail and destroy all
> copies of the original message.
>
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>
>
>
>
> browse
> Subscriptions page,
> FAQ,
> http://www.matronics.com/Navigator?AeroElectric-List
>
>
> Admin.
>
>
>
>
>
>
>
>
>
>
>
__________________________________________________
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Software in the cockpit |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
Great analysis.. Just a few embedded comments.
> On Jun 27, 2006, at 12:07 PM, FLYaDIVE@aol.com wrote:
snip
>
> OTOH, Microsoft bases their development on the proliferation of new
> features, not on ensuring that the existing features are without
> error. In fact, Microsoft "fixes" software by layering more software
> on top to mitigate the behavior of underlying software. (I have been
> wracking my brain to think of a good mechanical analogy but I can't
> come up with one because mechanical things just aren't made this
snip
Sure... Lots of things are made this way. How about fuel delivery
controlls on cars from about 1974 to about 1990 (year varying by brand and
model)? Smog limits were imposed. Manufactures mostly chose to do the
minimum bandaid fix to meet the latest standard. This led to labrynths of
vacuum lines, some of which seemed to go nowhere.. Instead of doing a
complete redesign to manage fuel flow vs. airflow precisely, they said
"well, if we mechanically compensate for altitude a little, and add a
little bit of exhaust to the intake once in a while, we'll pass the latest
criteria." Kept glueing things on until system reliability was really
pretty horrible after a few thousand miles.
> It took months to find the problem. The problem turned out to be a
> simple little throw-away feature that someone hacked into the real-
> time clock function of the machine. All the feature did was calculate
> the phase of the moon. It wasn't documented. It was so simple. It was
> probably the work of a bored programmer late some night. It is just
> that the programmer allocated one byte too little for one variable
> and the software wrote off the end of the variable into someone
> else's memory causing the operating system to crash. Unfortunately it
> took things like student registration and payroll with it when it died.
>
That's a great story.. Before the days where a kernel didn't allow
segmentation violations.. Today, we pretty much have to live with
software that mallocs, but doesn't free properly, but at least the program
can't usually crash the kernel. They system usually just slowly runs out
of real memory, then swap..
> Brian Lloyd 361 Catterline Way
> brian-yak AT lloyd DOT com Folsom, CA 95630
> +1.916.367.2131 (voice) +1.270.912.0788 (fax)
>
> I fly because it releases my mind from the tyranny of petty things . . .
> Antoine de Saint-Exupry
>
>
Message 14
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Software in the cockpit |
--> AeroElectric-List message posted by: "Malcolm Thomson" <mthomson@showmeproductions.com>
Very well put.
Ex-President, Blue Mountain Avionics!
-----Original Message-----
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ernest
Christley
Sent: Tuesday, June 27, 2006 9:27 AM
--> AeroElectric-List message posted by: Ernest Christley
--> <echristley@nc.rr.com>
AeroElectric-List Digest Server wrote:
________________________________ Message 24
____________________________________
Time: 06:25:55 PM PST US
--> AeroElectric-List message posted by: "Alex Peterson"
--> <alexpeterson@earthlink.net>
>> Pilots who *think* they understand computers will trust their lives
>> to them, and pilots who truly *do* understand computers will not.
>
>
>Except for those pilots driving cars less than about twenty years old
>to the airport, and who may pull out in front of another car, trusting
>that the car's computer will keep shoving gas and spark in!
That is an insiduous mistake, Alex.
A) My car has mechanically actuated brakes.
B) I expect the other car to have mechanically actuated brakes.
C) I am able to validate the health of the onboard computer in a very
low-risk environment before performing the high-risk maneuver. The engine
is running while sitting at the stop light, after all.
D) I 'trust' that the engine computer's software is not built on top of a
hacked version of DOS3.1 with three different graphic libraries, a widget
library, a tftp server, a TCP-IP stack, a general purpose command line
interpreter, a Java byte-code interpreter and Perl. Think I sound
ridiculous. I've worked on embedded systems built this way.
E) Car makers have huge engineering staffs with salaries amortized over
thousands if not millions of units. Staffs that are paid well to do the
boring and tedious jobs of software validation. This job is boring,
thankless (nobody likes the guy that says the software doesn't work), and
sucks in general. I wouldn't do it if it didn't allow me to buy so many
airplane parts.
The point is, software ain't software ain't software, anymore than bolts is
bolts is bolts. People who would faint at the idea of using a course thread
bolt from the BigBox Hardware store will happily throw a mission critical
box in their panel without a thought. Well, actually there is a thought.
The thought is, "Those software guys are all so smart. Just look at what
Bill Gates and Steve Jobs did in their garages. This new SuperEFIS is all
bright and shiny, with cool graphics and lots of buttons, and if it breaks
it will phone home through a satellite connection to the Internet and update
itself. It's going to make my flying so easy." That thought should receive
the same esteem that would be received from the guy walking down the bolt
section at Lowe's going, "Ooh! Shiny stuff."
Someone asked me if I were endorsing Dynon over BMA. I'm not; though, my
current plan is to purchase a Dynon unit. I'm endorsing a set of criteria
to choosing what software goes in your cockpit. When evaluating a unit,
conisider these questions:
1) Does the level of glitz and functionality correlate with the size of the
company and the number of units they expect to sell? There is no free
lunch. Software has to be validated, and that's expensive, because it is
boring, tedious and no one wants to do it. If the company has three
employees, and the unit has more functionality that a Garmin396 at 1/2 the
price....you'll probably be a beta tester.
2) Do you get the feeling that the software would be useless without the
hardware, or is this something ported from a PC game? General purpose
software is just that 'general purpose'. Lots of compromises and
obfuscations are made on the way from here to there. The idea that the
software is tied to the hardware will mean that the software knows the
limits of the hardware and can check that data recieved from the hardware is
not out of bounds. The more 'stuff' that is inserted between the hardware
and the decision making portion of the software, the more chances there are
for things to screw up and the more time the processor spends bookeeping
data that has nothing to do with showing you which way is up. Nothing is
more fun in a development organization that watching the software side
saying a problem is a hardware issue, while the hardware guys say that a
software fix is needed. Those issues occur less and less the closer the two
are tied together.
3) How often are updates released? 'Update' is an interesting word in the
software field. An update used to mean additional code to add functionality
for a changing world. It has slowly been morphed by companies not wanting
to admit that they have sold you crap-in-a-box. It now means "a
self-administered field repair". If your looking at a car that has a
history of needing a repair once a month, would you drive off the lot with
it? And yet you would call that a 'feature' in a piece of software? A
piece of software that you expect to tell you which way is up when you can't
see the ground? An EFIS, or any other embedded software, doesn't live in a
changing world. It is spec'd to tell up from down. Up is up and down is
down. Until those change, an update isn't. It's a field repair.
4) Are the company representatives 'excited' about new technologies? You
can leave this one off if you'd like. It's my bias showing. My experience
is that older engineers tend to view new software 'methodologies' with a
critical eye. The younger guys tend to jump on the latest software fad with
exuberence, generally breaking things that were working and needing more
hardware horsepower to do boot. I've watched myself get less exuberant and
more critical as the years have passed. A representative that is ready to
jump in an unproven software technology without careful consideration of the
cost/benefit equation is a red flag for me. The experienced guys know that
it is the same ol' stuff, with a different set of headaches.
I'm not trying to steer anyone away or to a particular unit. I'm just
saying that the software in the cockpit deserves the same amount of
consideration as any other piece of the airplane.
Bob K, I'm going to vehemently disagree with the assertion that we can build
a simple autopilot and have it controlled by PocketPC type device that we
would not rely on. Humans don't work that way. Once it is discovered that
the PocketPC will fly the plane just dandy on a smooth air day, we start to
trust it. Still works in minor turbulence, we trust it a little more. We
take it into IMC and it starts to get the leans...unfortunately, we trust it
as it flies us into cumulous granite. Do not put any software in control of
your airplane unless you trust it completely from the outset. I'm not
saying a autopilot should not be done, I'm saying that software that can not
be fully validated should not be considered.
--
,|"|"|, Ernest Christley |
----===<{{(oQo)}}>===---- Dyke Delta Builder |
o| d |o http://ernest.isa-geek.org |
--
No virus found in this incoming message.
--
Message 15
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "LarryRobertHelming" <lhelming@sigecom.net>
Lee, I can say after having wired and completed my RV7 last year that you
will need lots of 22 AWG wire. I suggest you think of the colors you will
use. Something like red for power wire, black for ground, and yellow or
white for control. You will need some other size wires and 18 is one of
them. You will also need some heavier wire but not great lengths. In the
starter and alternator and battery cables you will need 2 and 4 awg wire.
But you will mostly need 22 AWG. I originally bought several hundred feet
and had to buy more. I wish I could tell you exactly how much of each color
you need but I can't with any accuracy. Depends a lot on what your
instruments and electrical needs are and type of plane. My system is 12V.
Best wishes. Larry in Indiana
----- Original Message -----
Sent: Tuesday, June 27, 2006 2:58 PM
> --> AeroElectric-List message posted by: lee.logan@gulfstream.com
>
> Oldest question in the book and perhaps heresy on this site, but here goes
> anyway: Greg Richter "Aircraft Wiring for Smart People" recommends 18 and
> 22 guage wire for nearly all requirements but presupposes a 24 volt system
> per his recommendations. I'm at work and looking to order some of the
> wire
> for the next steps in my project and don't know what the equivalents would
> be in a 12 volt system. Do I step up one size or two or is there some
> other formula that applies? I have The Aeroelectric Connection at the
> hangar but I need to order some of this from here at work. Any help?
>
> Lee...
>
> Lee Logan
> Government Programs and Sales Support
> Gulfstream Aerospace Corporation
> Savannah, Georgia
>
>
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> This e-mail message, including all attachments, is for the sole use of the
> intended recipient(s) and may contain legally privileged and confidential
> information. If you are not an intended recipient, you are hereby
> notified
> that you have either received this message in error or through
> interception, and that any review, use, distribution, copying or
> disclosure
> of this message or its attachments is strictly prohibited and is subject
> to
> criminal and civil penalties. All personal messages express solely the
> senders views and not those of Gulfstream Aerospace Corporation. If you
> received this message in error, please contact the sender by reply e-mail
> and destroy all copies of the original message.
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>
>
Message 16
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Avionics Stack - Single Point Grounding... |
--> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch>
Brian Lloyd wrote:
> The bottom line is that, if it has a metal case the manufacturer expects
> the case to ground to the airframe through the panel, or at least there
> is a very good chance that it will. If they don't want the case grounded
> you will find something about that in the documentation and they will
> provide the wherewithal to insulate the case.
Thanks a lot for the info.
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|