Today's Message Index:
----------------------
1. 05:45 AM - Re: Re: crowbar method (Matt Jurotich)
2. 05:45 AM - Electric Tail wheel tug (Paul McAllister)
3. 06:10 AM - Re: Electric Tail wheel tug (Gerry Holland)
4. 06:28 AM - Re: Re: crowbar method (Robert L. Nuckolls, III)
5. 06:39 AM - Re: Electric Tail wheel tug (Phil Birkelbach)
6. 06:50 AM - Re: Crowbar CB "problem" (Robert L. Nuckolls, III)
7. 06:55 AM - Re: Crowbar CB "problem" (Phil Birkelbach)
8. 06:57 AM - Re: Electric Tail wheel tug (Mark R Steitle)
9. 08:12 AM - Re: Diode orientation (Robert L. Nuckolls, III)
10. 08:25 AM - Re: Two Mags & One Input to Electric Tach (Robert L. Nuckolls, III)
11. 08:28 AM - Re: I'm happy...:) (Robert L. Nuckolls, III)
12. 08:54 AM - Re: Crowbar CB "problem" question (Richard Riley)
13. 09:47 AM - Re: I'm happy...:) (Hinde, Frank George (Corvallis))
14. 10:23 AM - Z-22 question (John Swartout)
15. 11:13 AM - Re: Real data on OVP/etc (disinterested? DELETE) (Robert L. Nuckolls, III)
16. 11:26 AM - Re: Z-22 question (Robert L. Nuckolls, III)
17. 11:37 AM - Re: Crowbar CB "problem" question (Robert L. Nuckolls, III)
18. 11:38 AM - Re: Re: Real data on OVP/etc (disinterested? (Gerry Holland)
19. 12:09 PM - Re: Crowbar CB "problem" question (Joseph Larson)
20. 01:27 PM - Re: Crowbar CB "problem" question (Robert L. Nuckolls, III)
21. 01:39 PM - Re: Electric Tail wheel tug (Paul McAllister)
22. 01:50 PM - Re: Electric Tail wheel tug (Robert L. Nuckolls, III)
23. 01:51 PM - Re: CAD software (Robert L. Nuckolls, III)
24. 01:55 PM - Re: Electric Tail wheel tug (Robert L. Nuckolls, III)
25. 02:08 PM - Re: Electric Tail wheel tug (Dj Merrill)
26. 02:53 PM - The fatwire ground blues . . . ()
27. 05:06 PM - Re: Re: Real data on OVP/etc (disinterested? DELETE) (LarryRobertHelming)
28. 11:35 PM - Fw: CAD software (Steve Sampson)
Message 1
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| Subject: | Re: crowbar method |
--> AeroElectric-List message posted by: Matt Jurotich <mjurotich@hst.nasa.gov>
Bob et all
The part number for the breaker referenced below is?
Your supposition is correct. The breaker in B&C's test
stand for their regulators has experienced thousands
of crowbar events (150 A or so in 14v mode, 300A in
24v mode) and last time I checked with Tim, the breaker
in place today was the one I installed there about
15 years ago. Granted, it's a high-end product equal
to the miniature breakers used in the majority of our
aircraft at RAC.
Thanks
Matthew M. Jurotich
NASA/Goddard Space Flight Center
Swales contractor to the
JWST ISIM Systems Engineer
m/c : 443
e-mail mail to: <mjurotich@hst.nasa.gov>
phone : 301-286-5919
fax : 301-286-7021
JWST URL: <http://ngst1.gsfc.nasa.gov
Message 2
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| Subject: | Electric Tail wheel tug |
--> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
Hi all,
I know this is a little off topic but I am searching for mechanical components
to construct an electric tail wheel tug. I need a small axle with a right angle
drive similar to a differential. I have been searching the WEB but I end up
with too many hits. I was thinking something from an electric wheel chair manufacturer
might be able to be adapted. If anyone could suggest a few URL's
to browse I'd appreciate it.
Thanks, Paul
Message 3
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| Subject: | Re: Electric Tail wheel tug |
--> AeroElectric-List message posted by: Gerry Holland <gholland@gemini-resourcing.com>
Paul Hi!
> I know this is a little off topic but I am searching for mechanical components
> to construct an electric tail wheel tug.
Old age has arrived then mate!! Bewilderment is the next stage!
Regards
Gerry in UK
Do not archive
Message 4
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| Subject: | Re: crowbar method |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:43 AM 8/2/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: Matt Jurotich
><mjurotich@hst.nasa.gov>
>
There are LOTS of part numbers. They are members of a class
of breaker offered to the aerospace and upper-end commercial
applications. Examples include:
http://www.aeroelectric.com/Pictures/circuitbreakers.jpg
http://www.ti.com/snc/products/controls/acb-2tc.htm
http://www.ti.com/snc/products/controls/acb-7277.htm\
http://www.ti.com/snc/products/controls/acb-7274.htm
http://aerospace.eaton.com/products/power_load_subsystems/circuit_breakers.html
There are plenty of other suitable breakers not the
least of which are the Potter-Brumfield products offered
by Wicks. They also offer the miniature breakers at
http://wicksaircraft.com/catalog/product_search_results.php/search=Y2lyY3VpdCBicmVha2Vy
B&C has the miniature breakers suggested above.
Aircraft Sruce offers the miniature breakers at:
http://www.aircraftspruce.com/menus/el/circuitbreakers.html
The list of suitable breakers is huge. The only breakers
that have given me pause for concern that have surfaced
in the OBAM aviation community are some miniature, toggle
breakers that cost about $3 each are offered in someone's
pre-assembled power distribution product. The name escapes
me right now.
Bob . . .
Message 5
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| Subject: | Re: Electric Tail wheel tug |
--> AeroElectric-List message posted by: Phil Birkelbach <phil@petrasoft.net>
How 'bout a right angle drive for a drill?
...or go to a pawn shop and buy a big angle grinder and gut it. I bet
that gear box could take some abuse.
I once knew a guy that built a tug to pull his Bonanza around out of a
1/2" electric drill motor. You might also search around the hobby robot
builders sites. They have good sources for stuff like this.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB - Finishing Up
http://www.myrv7.com
Paul McAllister wrote:
>--> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
>
>Hi all,
>
>I know this is a little off topic but I am searching for mechanical components
to construct an electric tail wheel tug. I need a small axle with a right angle
drive similar to a differential. I have been searching the WEB but I end
up with too many hits. I was thinking something from an electric wheel chair
manufacturer might be able to be adapted. If anyone could suggest a few URL's
to browse I'd appreciate it.
>
>Thanks, Paul
>
>
>
>
Message 6
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| Subject: | Re: Crowbar CB "problem" |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 06:09 PM 8/1/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "Troy Scott"
><tscott1217@bellsouth.net>
>
>Bob, Charlie, Eric, All,
>
>If there's really a concern about the possible inappropriateness or lack of
>reliability of a common CB in the Crowbar OVP application, why not just use
>a fuse? It could be located in an easy-to-reach spot. We could carry a few
>spares..... What's the big deal?
Excellent question! In fact, some early American/Grumman products
did just that. Crowbar OV protection in the form of a 16v zener
(had to be a glass device, the plastic ones would blow up) downstream
of a field supply fuse. If the alternator ran away, the zener would
FALI SHORTED and take out the fuse. This was a dirt cheap, effective,
but ONE-SHOT protection method.
If you do get a nuisance trip, then it could not be reset in
flight. Further, the designers tied the fuse into the wire bundle
behind the panel. If the system ever operated, you had to replace
both fuse and zener. Not very user or mechanic friendly.
We elected to go with breakers since they were already in place
in our customer's inventories and a part of their standard bag-
of-tricks. Crowbar ov protection was slated to go onto Beech's
Model 38 (Turbine Bonanza). Seems that of ALL OV protection
systems available to Beech at the time, the regulator modified
with crowbar ovp was the only one that would catch a 70A, 12,000rpm
runaway 50x in a row and still meet specs on the 51st try. Unfortunately,
the program died (seems Bonanza wings wouldn't hold enough fuel
to make a turbine powered, go fast version fit Beech Marketing's
business model). The last time I saw the airplane, it was sitting
outside Bert Rutan's hangar at Mojave looking very much stripped
down.
http://www.aeroelectric.com/Pictures/38P.jpg
Burt got it when he split the sheets with Beech during the
Linden Blue era . . . all he wanted out of it was the
engine and panel mounted stuff.
In a message dated 08/01/2005 5:11:36 PM Central Standard Time,
tscott1217@bellsouth.net writes:
why not just use
a fuse?
>>>
One advantage of breaker is notification of OV event- you'll see it popped
out...
Yup, that works. But it's still takes a back seat to
ACTIVE NOTIFICATION of low voltage in the form of a
light flashing right in your face.
Bob . . .
Message 7
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| Subject: | Re: Crowbar CB "problem" |
--> AeroElectric-List message posted by: Phil Birkelbach <phil@petrasoft.net>
You can put an LED and resistor in parallel with the fuse and this would
give you indication. We buy these little fused terminal blocks at work
that have this little circuit built in. The drawbacks are that you have
to have a little bit of a load downstream of the fuseblock or they don't
indicate properly. This may not be an issue in this case. Also you
can't troubleshoot the circuit with a voltmeter like you would think
because the LED will let a few milliamps through and you'll read voltage
downstream of the fuseblock even with a blown fuse.
Also keep in mind that this is a parts count increase to solve a problem
that seems to only exist on datasheets and not in the real world. My
plane has P&B circuit breakers and a crowbar OVM on each alternator, and
I ain't worried a bit. The point is to protect my $xxK dollars worth of
radios from the insane alternator not to protect the circuit breaker
from doing it's job. If I have an OV event and the breaker pops and
dies then I'll fix the OV and replace the CB, smiling the entire time
that my avionics are all oblivious to the fact that the event took place.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB - Finishing Up
http://www.myrv7.com
Here's a cheesy circuit diagram...
+12Vdc -----+----(Fuse)-----+-----> Load
| |
+-\/\/\--(LED)--+
Fiveonepw@aol.com wrote:
>--> AeroElectric-List message posted by: Fiveonepw@aol.com
>
>In a message dated 08/01/2005 5:11:36 PM Central Standard Time,
>tscott1217@bellsouth.net writes:
>why not just use
>a fuse?
>
>
>
>One advantage of breaker is notification of OV event- you'll see it popped
>out...
>
>Mark
>
>
>
>
Message 8
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| Subject: | Electric Tail wheel tug |
--> AeroElectric-List message posted by: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
Paul,
As I recall, there was a recent article in Kitplanes on how to build a
low budget tug from spare bicycle parts. I don't recall the exact
issue, but it was within the last six months.
Mark S.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul
McAllister
Subject: AeroElectric-List: Electric Tail wheel tug
--> AeroElectric-List message posted by: "Paul McAllister"
<paul.mcallister@qia.net>
Hi all,
I know this is a little off topic but I am searching for mechanical
components to construct an electric tail wheel tug. I need a small axle
with a right angle drive similar to a differential. I have been
searching the WEB but I end up with too many hits. I was thinking
something from an electric wheel chair manufacturer might be able to be
adapted. If anyone could suggest a few URL's to browse I'd appreciate
it.
Thanks, Paul
Message 9
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| Subject: | Re: Diode orientation |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:25 PM 8/1/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: Charlie Brame <chasb@satx.rr.com>
>
>Bob,
>
>Thanks for the reply. You, and others, pointed out that the small band,
>regardless of the color, indicates the "cathode" end. That solved my
>problem - the various colors had me confused. As you surmised, the
>Navaid manual uses a "comic book" wiring diagram.
>
>As to the need to hook the comm to the autopilot, I quote from the
>Navaid manual:
>
> " The diode installed in series with the push-to-talk line,
>together with the wire connected from the PTT switch to pin 7, are used
>to kill the signal to the servo while the PTT switch is depressed. This
>prevents the servo from jumping around due to the presence of high level
>RFI on the servo power lines. The servo stays engaged during the voice
>transmission, but it does not move until normal operation is restored by
>releasing the mike button."
>
>The manual goes on to say that a metal airplane with shielded wires
>probably will not have a RFI problem, but that a composite airplane with
>unshielded wires probably will. My RV is metal, of course, but I have an
>obvious RFI problem with my unshielded trim indicator circuitry, so I
>figured connecting the diode as shown was good insurance.
Hmmmm . . . some more of that "best practice" stuff.
I was afraid that's what you were going to say. I talked
with the Navaid guy (Doug something?) at OSH in '86 or '87 at
some length. This was before he graduated from a table in
the Flymarket to a booth in the commercial buildings. We
discussed EMC issues even then and I offered to help him make
his design RFI bullet proof. We discussed the same issue
several times in intervening years but I was never offered
the opportunity to contribute.
Words in the manual concerning shielding illustrate a lack
of understanding on the part of the writer. Shielding's benefits
are quite specific to breaking the capacitive (or electrostatic)
coupling mode between wires. It can have some limited benefits
in reduction of radiated interference where it becomes a sort
of short conduit, like on spark plug wires.
However, shielding as a general prophylactic measure against
RF intrusion or emissions is a very mixed bag. This is because
shielded wires in signal and power bundles are NEVER treated
as matched impedance transmission lines (al la coax antenna
feeders). I've seen cases where it helped not at all or even
made things worse.
The #1, sure fire, best bet, works-every-time technique is to make
one's black boxes immune to expected stress levels with appropriate
design of the input-output circuitry including use of filters
as needed.
Unfortunately, it seems that NavAid has not learned of this
fact in over 20 years. I'll suggest that risks to your
installation are quite low due to the metal airplane being
a strong attenuator of interference coming from antennas
outside. You might leave the diode out and see what happens.
It would be an interesting experiment to see how it goes.
Further, as a consumer of their products, you are entitled
to bang on their cage pretty good about this library-paste-
and-bubble-gum approach to EMC control. If you have occasion
to contact them in the future, you might suggest there's
this gray haired ol' fart in Wichita who is STILL waiting
to help them move their products into the present age.
Bob . . .
Message 10
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| Subject: | Re: Two Mags & One Input to Electric Tach |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 10:39 PM 8/1/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "r falstad" <bobair8@msn.com>
>
>I would like to use a Radio Shack submini DPDT switch so my
>Westach/Westberg Mfg. electric tach can read RPM on each magneto. I'm
>thinking of running a single conductor shielded 18 AWG wire from each mag
>switch (the same wire I'm going to use for the "P" leads) to the DPDT
>switch. I'll terminate the conductors and the shields separately for each
>side of the switch so when I throw it, I won't have the shield from the
>other "P" lead making contact as I would have to do if I used a SPDT switch.
>
>Does this sound like it will work?
Sure. but you can make it simpler yet. See:
http://www.aeroelectric.com/Pictures/elect_tach2.gif
here I show the starter lockout circuit that prevents
operation of starter with the non-impulse coupled
magneto turned on. If you don't have/need this feature,
then the circuit can be implemented with one 2-pole
and a single pole switch. If you use shielded wire
from mag switches to tach, then ground at tach end
only. This eliminates the need for a third switch just
to service the tachometer signal.
Bob . . .
Message 11
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| Subject: | Re: I'm happy...:) |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 02:00 PM 8/1/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)"
><frank.hinde@hp.com>
>
> With my all electric airplane (Lycoming with Emags and elctric fuel
>pumps only) I have found that by using a simple com radio (backup to GNS
>430) in receive mode and transponder I can get my total current draw
>down to a shade under 8 amps which fits nicely into the SD-8 backup.
>
>Using Bob's 3 buss design I can easily save my battery reserve to do the
>approach/run the lights for when I land.
>
>The above assumes I run only one fuel pump (I have one in each wing
>root) and one Emag.
>
>Having a Pmag on a dual alternator systems seems like two layers of
>redundancy to me...Do we agree?
You had "layers" before going to p-mags. Changing from e-mags
to p-mags is yet another layer. The neat thing about p-mags
is that they are totally independent of the electrical system
for normal operations in flight . . . this might suggest that
p-mags are not a layer on top of existing layers but a side-by-side
substitute for interdependent operations. A simple, very sensible
approach to ultimate system reliability.
Bob . . .
Message 12
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| Subject: | Re: Crowbar CB "problem" question |
--> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
For those that have experience with an external regulator -
particularly one of the B&C regulators - how often do the nuisance trips occur?
If we're worried about the nuisance trips degrading field CB's, would
it be a reasonable fix to replace those CBs at annual?
Message 13
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--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
Hmm...true and It saves yet another precious amp, significant when you
only have 8 of them in a high stress IFR/alternator goes south
environment.
I guess I was coming from the perspective that my FI pumps are as
critical as the ignitions. The chain is only as strong as its weakest
link. In other words there is no point in adding functionality to run
the igntion if the FI pumps are dead anyway.
For another 200 bucks to go from an EMAg to P mag I guess its pretty
much a moot point in a $90k aircraft...Still can't believe I'm spending
this kind of money!..:)
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L. Nuckolls, III
Subject: Re: AeroElectric-List: I'm happy...:)
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
--> <nuckollsr@cox.net>
At 02:00 PM 8/1/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "Hinde, Frank George
(Corvallis)"
><frank.hinde@hp.com>
>
> With my all electric airplane (Lycoming with Emags and elctric fuel
>pumps only) I have found that by using a simple com radio (backup to
>GNS
>430) in receive mode and transponder I can get my total current draw
>down to a shade under 8 amps which fits nicely into the SD-8 backup.
>
>Using Bob's 3 buss design I can easily save my battery reserve to do
>the approach/run the lights for when I land.
>
>The above assumes I run only one fuel pump (I have one in each wing
>root) and one Emag.
>
>Having a Pmag on a dual alternator systems seems like two layers of
>redundancy to me...Do we agree?
You had "layers" before going to p-mags. Changing from e-mags
to p-mags is yet another layer. The neat thing about p-mags
is that they are totally independent of the electrical system
for normal operations in flight . . . this might suggest that
p-mags are not a layer on top of existing layers but a side-by-side
substitute for interdependent operations. A simple, very sensible
approach to ultimate system reliability.
Bob . . .
Message 14
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--> AeroElectric-List message posted by: "John Swartout" <jgswartout@earthlink.net>
Rooting around the AEC website, I pulled up this diagram:
http://www.aeroelectric.com/PPS/Engine/Starter/PM_Starter_w_RunOn_Relay.
pdf
which is essentially Z-22 with what I believe is a bridge rectifier
added. I don't recall seeing mention of this anywhere else. Which is
the preferred architecture?
Also, I'm wondering about the sizing of the fuse (1A) on the line from
the Main Power Distribution Bus in the drawing referenced above. This
is much smaller than the 7A fuse on the 22AWG starter line in Z-13/8,
and much smaller than the 5A that would normally be used to protect a
22AWG wire. I wonder if there is a reason for the more expensive 1A
fuse.
Also, if the rectifier is recommended, would the Radio Shack 276-1185
called out for the E-bus normal feedpath also be appropriate here?
Thank you.
John
Message 15
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| Subject: | Re: Real data on OVP/etc (disinterested? DELETE) |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:50 AM 7/28/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
>
>Bob;
>
>Take a deep breath and read carefully and ignore any non technical parts but
>please consider the technical comments as worth considering as many are
>industry wide technical info.
>
>Sorry for your upset
I have never been more calm. There is ALMOST nothing you've stated
in your writings here that are worthy of an emotional investment.
> . . . but as usual you have missed my point and not addressed
>MY technical issues in a technical manner, merely replied with a personal
>assault (and perhaps properly deserved). There are some technical details
>here in this post as you requested and some are a repeat of my much earlier
>posts, but I digress. Here is some of the data you asked for.
<snip>
>I am still waiting for ANY worst case design analysis showing any of your
>designs is usable in all likely applications. Some of the possible false
>tripping have been reported by buyers (not builders) of the OVP and all who
>contacted me wanted to remain anomalous (nor were they interested in a
>refund), just a good approach to the design issue as Vans says to not use
>any OVP design (yours or similar approaches).
Which only illustrates the ignorance of our customers
promulgated by your rhetoric and Van's equally ignorant
advice. It may well be that those customers were experiencing
the same difficulty that we discovered on the Bonanzas which
we were happy to rectify for Raytheon and would have been
equally happy to rectify for others except that they'd
bought into a bill of goods that painted us as incompetent.
The only case I was made privy to, the pilot MANUALLY SWITCHED
the alternator on and off under load. It did not involve
a nuisance trip. In fact, I doubt that ANY of the failures reported
to Van involved real nuisance trips . . . but it's an easy thing
for unhappy customers to improperly assign blame given some
highly touted but mis-informed opinions being circulated.
> As we have no info on the sold
>OVP design, its not possible to accept your statement that only the builders
>versions are at fault. I for one wonder why the sold version would be any
>different schematically.
For very good reasons which I would have provided if you
had asked. The sold versions are the same DIY version of
some years ago before the MBS4991 went obsolete. B&C did
a lifetime buy of the part to continue production of that
design but we needed another approach for the DIY circuit (which was
built, tested, qualified and incorporated into some production
units - except for the toe stubber that Ken pointed out
earlier this week).
>You have suggested many times that somehow the Vans rebuilt alternators have
>poor quality regulators and that is why they fail at a extremely hi rate
>when used with your OVP. From what little data I could find its a failure
>rate of 10% or much higher. Clearly something unique in the application of
>the wiring in Vans designs or ????? Some were purchased OVP and not built up
>units.
It was a hypothesis . . . .do you have another? But let's not
mix apples and oranges. The style of OVP has nothing to do
with the failures of Van's alternator. The very act of switching
the alternator OFF while loaded seems to be the trigger event.
This happens whether it's an ov trip from a crowbar module, Eric's
OVP module, or simply operating the switch on the panel. I'm
certain that it's a load-dump event that kills the alternator's
own regulator.
This is an issue SEPARATE from and not affected by style of OV
protection.
>"Rebuilt" alternators is really a false name in the industry. They are only
>repaired (what is failed is replaced, what still works is not replaced) and
>the ND 60 amp unit has been around for at least 25 years. Many units have
>been "rebuilt" several times. I contacted several major rebuilders around
>the country (including Bosch) as well as a couple of local ones and found no
>one replaces anything still working. Not even bearings were normally
>replaced in some cases. Thus a "new rebuilt" alternator might have an
>original 25 year old regulator or a cheep low quality import replacement or
>a modern but still low cost replacement. None admitted they used OEM (ND)
>regulators as replacements. The typical reply was "price competition"
>prevented that approach. Thus its not possible to single out Vans as having
>poorer alternators than others.
>
>The comments that in affect state my OVP is not the problem its Vans low
>quality rebuilds is what is upsetting. (MY S%&T does not smell :-) )
I've never said that my design could not have been root
cause of failures in Van's alternators due to any
particularly "golden" design. What I said was that Van's
alternators were failing because they were being unloaded
by mis-use of switches to control the alternator that were
PART of the ov system . . . the same damage would have
happened irrespective of who's ov module was used . . . or even
if no ov module is included in the b-lead control concept.
Eric currently publishes an ov protection scheme utilizing
the Killovac contactor which will fix the contactor performance
issue . . . but guess what? It will still kill alternators
for exactly the same reasons as before.
>Then I contacted a design engineer in the semi industry responsible for the
>modern one-chip regulator (not the one used by ND) and described the problem
>we were having. The reply was the design would protect against the normal
>load dump but was unlikely to survive a contactor contact arcing and the
>opening a loaded output "B" lead. This agrees with several different
>automotive test requirements for alternator design testing. The industry is
>designing to the automotive equivalent of the aircraft DO-160 which is more
>severe.
>
>At present the only known reasonably priced contactor RATED to open the "B"
>lead is the Kilovac. The common contactors available are not rated to open
>the voltages likely to be found under fault conditions.
Agreed. Which address only ONE issue. Contactor performance
as a b-lead controller. It has no bearing on either style
of ov protection used or on failures of alternators due to
load-dumping.
>I quote from a major relay manufacturers web site for contact application.
>
> "Improper or excessive suppression can cause the relay to suffer from a
>long release time, slow contact transfer, and contact bounce on break. All
>of these conditions will increase contact arcing when load switching, which
>will reduce relay life dramatically.".
>
>One site http://relays.tycoelectronics.com/kilovac/appnotes/transients.stm
>goes on to compare six different methods of coil "spike suppression" Its
>interesting to read this table and see that the common diode is the LAST
>choice and the Bi directional Zener (read bi directional transorb). There
>are similar tables in the USA and Europe and ALL suggest the last method of
>choice is the simple diode. The simple diode works as long as the contacts
>are carrying low currents and non inductive loads. In the case of the
>alternator its a very different matter as the unloaded unregulated
>alternator voltage can jump to hundreds of volts during the contact bouncing
>during opening even with the best coil suppression method thus the need for
>the Kilovac which is rated at hundreds of volts.
This is yet another isolated issue that goes toward potential slowing
of contact spreading velocity during opening. I've done extensive
testing and published results that show marked DELAY in contact opening
but not a significant slowing of spreading velocity. Tendencies to arc
during opening were exactly the same whether one used no diode,
a bi-directional Transorb or a plain diode.
If one is worried about opening delay, the Transorb is the way to
go. If one is concerned about best life for the controlling switch,
the diode is the best way to go. Since my designs didn't care about
delay time, I opted to stay with diodes.
See exemplar test plots representative of lots of tests on a variety
of relays and contactors:
http://www.aeroelectric.com/Pictures/704-1DelayNoDiode.gif
http://www.aeroelectric.com/Pictures/704-1DelayWithDiode.gif
http://www.aeroelectric.com/Pictures/704-1OpeningTimeNoDiode.gif
http://www.aeroelectric.com/Pictures/704-1OpeningTimeWithDiode.gif
>I find the use of the simple diode across relay contacts one of the most
>widespread miss information in the industry. IF ""Joe"" does it, it must be
>OK ,or if it was not good why are relays available with one built in?. It's
>very simple engineers are lazy and copy what others do far too often. Also
>it works in 99.9% of the cases. It does not work in a "B" lead contactor
>application however. Manufacturers will build what the engineers want
>regardless of its design value.
How is it mis-information if testing is used to deduce and
select from one of several controlling features? When diodes
were FIRST placed across the contactor coils in mid 60's, Transorbs
were not around . . . although we COULD have applied a variety
of spike snubbing techniques such as resistors or resistor-capacitor
networks.
The plain diode was used for decades across coil contactors
with great success for eliminating arc-induced wear on
controlling switches. Now comes the folks who are sifting the
grains of sand looking for the next quantum jump in relay/contactor
performance and the new kid on the block (Transorb) offers yet
another opportunity for improvement.
The question not asked and answered is: Do contactors and relays
in light aircraft operated enough cycles per hour, month, year
or even lifetime of the airplane for there to be even a measurable
improvement in service life of the device? A battery contactor
operates very lightly loaded and into a largely resistive load
and only once per flight cycle. Perhaps 50-100 times per YEAR
in a SE light aircraft. Starter contactors get the crap kicked
out of them once every flight cycle . . . which is why they're
specifically designed to take this extraordinary abuse. In BOTH
cases, use of a diode across the coil provides the same demonstrable
benefits for increasing life of the controlling switch since
we "discovered" them in 1965.
I'm not for a moment suggesting that substituting Transorbs for
diodes is a bad thing to do . . . but I object to any inferences
that my suggestions that diodes are "okay" is a promulgation of
"mis-information." I've been to the workbench, got out the test
equipment and demonstrated to my satisfaction that there is
no value in promoting Transorbs over diodes for the ways I
show them in my drawings.
>I have demonstrated this in my testing and I suspect its repeatable by you
>if you use a common contactor from Wicks for example. The contactor I used
>was from Wicks. In one case the bounce duration was quite long and included
>many bounces.
Opening bounce? I'm having trouble visualizing how contacts initially
moving apart reverse direction and move back together. What's the
forcing function? Bounce on closure is predictable and understandable.
I'd really like to repeat your experiment here too . . . please
show us the setup.
>My conclusion is never use a "rebuilt" internally regulated alternator with
>ANY OVP device that might false trip or trigger on a short transient.
This doesn't compute. Adding ANY form of b-lead control to ANY
internally regulated alternator is an adventure into unknown risk.
It has nothing to do with style of ov protective devices . . . false
tripping or otherwise. If one subscribes to the paradigm of being able
to CONTROL one's engine driven power source from the panel, then we
agree that a b-lead contactor is called for in every installation of
an internally regulated alternator.
Now, there is RISK that the alternator can be damaged by simply
turning it OFF while loaded whether the system included OV protection
or not.
> With
>a brand new ND alternator available for $300+ and the demonstrated failure
>rate in the auto industry being so low its unlikely any of us will ever see
>a "fail hi" condition in a lifetime of flight. Van does not recommend any
>OVP and with a modern regulator I agree its addition only reduces system
>reliability. The Fail HI mode of regulator failure is a very low
>probability in the failure modes of the modern regulator . Any failure of
>any type is extremely low in today's new production ND alternators.
Low . . . but not zero. Recall Jack's post of just last week:
--------------------------------
--> AeroElectric-List message posted by: "Jack Eckdahl" <jeckdahl@sjrwmd.com>
George: The alternator that failed was a nippon denso, 60 amp,
internally regulated. I'm not sure that my experience should cause
others to avoid this unit. I know that hundreds of airplanes are flying
successfully with them. However, if you read Bob's most recent post,
you might decide to avoid all internal regulated alternators.
Bob: As soon as I pull the fuel guage, I'll send it too you. What
address? thanks, jack
---------------------------------
>Use of any OVP has the potential of failing the alternator when it trips for
>what ever reason so IF a OVP is used it needs to be extremely reliable under
>all design conditions. It should never trip unless the OV is clearly of long
>duration. The AEC OVP device trips in a few milliseconds and really should
>not trip unless the OV is longer than what one might expect from a major
>load dump.
Agreed. But here you're substituting your design goals without
regard to the goals of our customers (who cited DO160/MS704) when
time constants were selected for the ov trip dynamics. The nuisance
tripping we've experienced has NOTHING to do with the OV sense
circuit and everything to do with dv/dt sensitivities of the SCR
which has shown that there are antagonistic events in SOME
systems that are NOT suggest by DO160/MS704.
After our epiphany, we made adjustments to the circuit for all
new production and for anyone who was plagued with the condition
in the field at no charge. This is a DISCOVERY of a phenomenon
not previously considered (by industry standard practices). No
amount of analysis would have predicted the condition we were
told did not exist (or at least was not previously identified).
The new requirement did not come to light until the Bonanza
production line produced a series of REPEATABLE EXPERIMENTS
critical to identification of root cause and deduction of remedies.
>YOU agreed there were cases of false tripping yet you failed to properly
>analyze your design. There was absolutely no reason for a real lab test and,
>in fact testing was a near total waste of time, as the false tripping
>depends on a specific implementation of the classic schematic. How do you
>expect to build all variations of a schematic??
You cite facts not in evidence. EVERY instance of a customer
reporting a nuisance trip problem has been dealt with in
a positive way if they only came forward with their
complaint. Just a few days ago, I upgraded an OV module
that worked as advertised for 4 years but became irritated
by a new accessory in the airplane.
We DID analyze the design, deduced modifications to fix the
problem, and offered the fix to anyone who needed/wanted it
at no charge.
>How can there be repeatable tests when several major components have
>important design tolerances or variables in the 5x or 10x range of
>tolerances. Battery internal resistances of 5-1 or more, CB resistances of
>10-1 or more. Schematic is one thing wiring diagram is another (how a
>schematic is implemented and where wires are connected along a common line
>in a schematic can and often does greatly affect the results.
I've given you the data that supports both my analysis and
test results. You still haven't told me what breaker you've
tested where the manufacturer says it goes tits-up on a 50x
overload.
>The time tested and standard method of circuit analysis is on paper with or
>without the help of software;
<snip>
> However the use of PC625 and the very similar PC680 are very popular
>around here as are the use of dual batteries often simple wired directly in
>parallel.
The batteries are not the controlling factor. Wiring and breaker
resistances are. Lets assume ZERO battery resistance but we still
have 0.04 ohms of breaker resistance and a couple of feet of
20AWG wire for another .04 ohms when combined with a 2v drop
across the SCR yields about 130 amps of crowbar current. If it
would make you feel better, we COULD add the admonition to our
installation manuals not to install the crowbar module or any
of the LR series regulators with zero length wires . . . but given
that most folks locate their equipment some distance from the
bus, that worry wasn't high on our list of concerns.
>You used 0.035 ohms for the CB and got trip times of a few MS. I used a CB
>from Wicks and measures it at 0.003 ohms and it tripped repeatetly in the
>50-70 ms range. Yes the data seems illogical but my data is repeatable here
>and I accept your data also as factual.
What was the brand and part number of this .003 ohm breaker?
Results you're reporting are so astounding that they
BEG for a repeated experiment. Please afford me the courtesy
of knowing how to do it.
I've uploaded data sheets on breakers I find in Wicks catalog
to
http://www.aeroelectric.com/Mfgr_Data/Breakers/Potter_Brumfield
The two P&B data sheets speaks of 0.030 +/-30% for max
breaker resistance on 5A breaker. Of course, this is a MAX
value. Did you find an exemplar breaker that presented a
resistance 1/10th this value?
I'm amazed that one can fabricate a 5A breaker heater with so
small a resistance. I've measured dozens of breakers by Woods,
Mechanical Products, Klixon, and Eaton-CH and they all agree with
their data sheets to present about 30-40 milliohms of series resistance
in a 5A breaker. Smaller breakers are markedly higher in resistance.
>There is no way you can reproduce my test data unless you use the exact same
>parts.
ABSOLUTELY! DEAD ON! By the same token, I cannot evaluate
the validity of your test data without knowing what parts you
used. You keep hammering me with these near zero-ohm breaker
values and I can't find anything approaching these values
in any products I can put my hands on.
>This is the fallacy of your requirements that the test must be
>reproducible by you to be valid.
???? Paul, this is a truly astounding statement from someone
to claims to be an engineer. No sir! For CLAIMS made by
ANALYSIS of test results to be valid, they should be
CAPABLE of being repeated by anyone who wishes to do
the work. OF COURSE this requires a complete disclosure
of all materials and techniques used. Remember the cold fusion
guys of about 15 years ago? They made claims that begged
critical review by repeated experiment. Remember Dave Blanton's
240 hp, 6-cyl Ford conversions? How about Jim Bede's super-sonic
OBAM product? Geesh! Just watch late night TV and you'll get
tons of information most of which would not stand up to
critical design review and repeated experiments. But the gullible
consumer is not privy to real data or experience that validates
the propagandist's claims. You might as well be watching a
Siegfried and Roy show and believing those lions really disappear.
Until they show me how I can make lions disappear, it's nothing
but propaganda with an agenda. In their case, the agenda is
is entertainment which I do enjoy. What's your agenda sir?
Data for repeatable tests are a COURTESY that REAL scientists
offer each other as and AID to investigating any phenomenon.
I expected and requested no more of you and I was fully transparent
in everything I used to base my claims. I've built a career
on repeatable test results in the lab and in my customer's
airplanes. Yes, things slip by sometimes - the only thing
we can do then is act in a responsible way to rectify
the problems as they arise.
>Perhaps its valid where the circuit
>variables are not so dependent on individual parts used but in this case the
>parts variation is so huge they prevent repeatable tests. Both tests are
>reasonable examples of the overall design as documented on your web site and
>neither are a worst case example as only a proper analysis can define the
>range of design results.
>
>ANY design that is to be reproduced must be analyzed using the specified
>data sheet parts variations (and either specify the exact parts of consider
>all the likely parts brands that could apply) and for general use NEVER
>publish a design that violates the data sheet under any condition or assumes
>parameters not specifically printed in the data sheet.
Pleeeasssss, purdy pleeeaasse, show me the data sheets.
>In any event I see no reason to continue posting.
That's fine too.
I sat in a meeting yesterday for several hours looking at about 50
pounds of paper on the table that included failure mode effects
analysis, reliability studies that assured us we were buying
a 7,000 hour MTBF product, test reports out the wazzoo,
detailed worst case analysis, etc. etc. These papers
presumably defined a system that we paid $millions$ for and
according to all the analysis, should be the golden product.
It won't run more than 10 hours without annunciating a failure
and causing our customers great concern and billing our coffers
many $killo$ of warranty csots. This golden system monitors
dozens of potential problem areas and if you believe the
marketing hype (we did) . . . it's the safest system ever to
fly.
Problem is, the designers forgot to offer a way to tell which
one of 5 dozen faults tripped out the system. Further, as far
as the FAA is concerned, the system is blessed (it passed all
the qual tests) and is carved in stone. Any changes (to
upgrade performance or to even fix simple nuisance trips) are
horrifically expensive and time consuming to implement.
I have a proven, flight-tested alternative system that has run fault
free for hundreds of hours. The system that works was afforded
perhaps 5% of the analysis and testing compared to the system that
doesn't work. Further, ALL operating characteristics of the
working system are observable at any time . . . INCLUDING
those characteristics that might produce shut downs.
If you want to apply the tools of detailed analysis to
the crowbar (or any other) ov protection system, you
must first cite ALL sources, magnitudes and configuration
of your hypotheticals. Only then may we debate results to your
heart's content as scientists. Analysis is a tool. It depends
on proper application of good input data and lucid interpretation
of results. These things are BEST conducted as cooperative
critical reviews where everyone's focus is on doing the
best thing for our customers and students and not lobbing
cabbages.
Now, HERE is where I DO get tense . . .
I'll continue to object to your rhetorical, unfounded
attacks on "my approach" when I'm the one who has thousands
of happy customers. The few secret, unhappiest customers are
those who accepted your hip-shot assessment of my engineering
integrity and business ethics to the extent that they (according to
you) won't take advantage of remedies I'm begging to offer. Further,
you have deprived ME of benefits for having field experience upon
which to deduce root cause of problems and to craft improvements
to my products and servics.
One of the KEY attributes of our society that served to build
us into an economic powerhouse in record time is that sacred
relationship between honorable suppliers and consumers who
walk away from every deal happy or at least free of fraud
or encroachment on their property.
How many times on this List have I encouraged individuals
with questions or complaints about any product to communicate
FIRST with the manufacturer/supplier? Give the supplier
an opportunity to do the right thing and support their
customers to the best of their ability and/or business model.
You have injected yourself into the relationship between
me and individuals who have invested in my goods or services.
Your actions, no matter how well intended, are costing me
undeserved loss of both good-will in the marketplace and valuable
feedback from my customers. Your actions have produced unhappy
customers AND suppliers through no fault of either. There are
no civil words in my vocabulary to adequately express how much
this displeases me.
If you do post, show me the data. If you choose not to post,
I wish you well but I'll continue to worry about your crusades
against myself (and probably others) who are not deserving of your
dishonorable disservice.
Bob. . .
Message 16
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| Subject: | Re: Z-22 question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 01:22 PM 8/2/2005 -0400, you wrote:
>--> AeroElectric-List message posted by: "John Swartout"
><jgswartout@earthlink.net>
>
>Rooting around the AEC website, I pulled up this diagram:
>
>
>http://www.aeroelectric.com/PPS/Engine/Starter/PM_Starter_w_RunOn_Relay.
>pdf
>
>
>which is essentially Z-22 with what I believe is a bridge rectifier
>added. I don't recall seeing mention of this anywhere else. Which is
>the preferred architecture?
Good find sir. I'd intended to update Z-22 to this configuration.
A builder wrote me some time ago asking about spike catchers
for BOTH the S704-1 AND the starter's built in contactor/solenoid.
Given that we needed TWO diodes and given further that wire-leaded
diodes are often clumsy to work with, this seemed like a new
opportunity for the diode bridge rectifier. Note that in this
case, we use two of the four diodes to accomplish the tasks
suggested by his query.
>Also, I'm wondering about the sizing of the fuse (1A) on the line from
>the Main Power Distribution Bus in the drawing referenced above. This
>is much smaller than the 7A fuse on the 22AWG starter line in Z-13/8,
>and much smaller than the 5A that would normally be used to protect a
>22AWG wire. I wonder if there is a reason for the more expensive 1A
>fuse.
7A was necessary to control the intermittent duty contactors
thought 20AWG wire to improve contactor performance under high
loads on battery.
1 to 5 A are fine for 22AWG wire that only drives the S704-1 relay.
B&C charges the same price for all values of the ATC fuse from
1 to 30 amps.
>Also, if the rectifier is recommended, would the Radio Shack 276-1185
>called out for the E-bus normal feedpath also be appropriate here?
Sure . . . mounts with one screw, doesn't need insulators, wires
with 1/4" faston tabs. What could be easier?
Bob . . .
Message 17
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| Subject: | Re: Crowbar CB "problem" question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:51 AM 8/2/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: Richard Riley <richard@riley.net>
>
>For those that have experience with an external regulator -
>particularly one of the B&C regulators - how often do the nuisance trips
>occur?
>
>If we're worried about the nuisance trips degrading field CB's, would
>it be a reasonable fix to replace those CBs at annual?
I guess that depends on the breaker. The ones I sold and
B&C sells are quite robust and don't present a service-life
issue. I lost track of LR series devices fielded when it passed the
2,000 mark years ago. I suspect it's over 3,000 now.
Until the Bonanza experience, we had a handful of reports
of nuisance trips virtually all of which were fixed by
identification and mitigation of the noise at the antagonist.
I've not been closely coupled to the B&C experience for several
years now so I cannot report first-hand about problems with
fielded systems. If there were any kind of crisis, I suspect
I would have had a call from them. You can contact Tim at
B&C if you're needing more current data.
There is a breaker in the B&C acceptance test fixture
that has been subject to test trips from every LR series
regulator produced since day one. As far as I know it's
still there . . . but again, you'll have to ask Tim.
If the breaker fails, it will present you no greater
an issue than for failure of any OTHER part in the
alternator system. That's what we design for . . . failure
tolerance.
This is a tempest in a teapot folks. Aside from an
admonition not to install B&C or AEC products with zero
length leads and breakers purchased from Duckwalls,
I can deduce no reason to be worried.
Bob . . .
Message 18
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DELETE)
| Subject: | Re: Real data on OVP/etc (disinterested? |
DELETE)
--> AeroElectric-List message posted by: Gerry Holland <gholland@gemini-resourcing.com>
> If you do post, show me the data. If you choose not to post,
> I wish you well but I'll continue to worry about your crusades
> against myself (and probably others) who are not deserving of your
> dishonorable disservice.
Are we back on course?...Sir
Regards
Gerry
Do not archive
Message 19
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| Subject: | Re: Crowbar CB "problem" question |
--> AeroElectric-List message posted by: Joseph Larson <jpl@showpage.org>
It's time to display my ignorance.
On Aug 2, 2005, at 1:37 PM, Robert L. Nuckolls, III wrote:
>
> This is a tempest in a teapot folks. Aside from an
> admonition not to install B&C or AEC products with zero
> length leads and breakers purchased from Duckwalls,
> I can deduce no reason to be worried.
I don't know what Bob means here. I haven't been able to keep up
with the entire conversation, there's just been so much going on with
it. I've been trying to read it, but I think it would be a full time
job.
What is meant by "zero length leaders" ? Bob, are you saying that
there's a right way and a wrong way to install these products?
Is there a particular issue with breakers from Duckwalls?
Color me ignorant.
-Joe
Message 20
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| Subject: | Re: Crowbar CB "problem" question |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 02:08 PM 8/2/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: Joseph Larson <jpl@showpage.org>
>
>It's time to display my ignorance.
>
>On Aug 2, 2005, at 1:37 PM, Robert L. Nuckolls, III wrote:
> >
> > This is a tempest in a teapot folks. Aside from an
> > admonition not to install B&C or AEC products with zero
> > length leads and breakers purchased from Duckwalls,
> > I can deduce no reason to be worried.
>
>I don't know what Bob means here. I haven't been able to keep up
>with the entire conversation, there's just been so much going on with
>it. I've been trying to read it, but I think it would be a full time
>job.
>
>What is meant by "zero length leaders" ? Bob, are you saying that
>there's a right way and a wrong way to install these products?
The right way is "follow the instructions". You have to go
out of your way to install these in a manner that increases
risks of problems. Even if there are "problems" risks to
safety of flight are tiny. The reference to "zero length"
leads is a mild side swipe at an experiment that exposes
vulnerabilities to the crowbar ov protection system by setting
it up in a manner that does not represent any way it would
be installed in an airplane. Obviously, we use WIRE to hook
things up and that wire has length because we can't stack
all the electrowhizzies into a 1 cubic foot space in the
airplane.
Bottom line is that the worst of the worrisome worst
case scenarios just doesn't happen.
>Is there a particular issue with breakers from Duckwalls?
That was a tongue in cheek reference to circuit breakers
of unknown pedigree. I'm aware of no "mainstream" supplier
to the OBAM aircraft community that supplies breakers
I cannot recommend.
Take a peek at:
http://www.velocityaircraft.com/Velocity%20Store/Avionics,Electrical,autopilots,instruments/prewired_systems.html
The breakers used in this assembly are not fabricated to
any design requirements that I can identify. Unsafe? No,
they'll probably open up when overloaded just as designed.
Robust? I don't think so, but I don't know either. Rather
than speculate, I'll choose to suggest you purchase from
Wicks, B&C, Aircraft Spruce, or our friend up at Steinair.
It's easy to suggest known good sources and very difficult
to identify and/or predict questionable sources.
>Color me ignorant.
But obviously willing to learn . . . keep up the good quesitons!
Bob . . .
Message 21
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| Subject: | Re: Electric Tail wheel tug |
--> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
Err, ahhh, Gerry who ?..... hang on I gotta go the nurse is coming
do not archive
> --> AeroElectric-List message posted by: Gerry Holland
> <gholland@gemini-resourcing.com>
>
> Paul Hi!
>
>> I know this is a little off topic but I am searching for mechanical
>> components
>> to construct an electric tail wheel tug.
>
> Old age has arrived then mate!! Bewilderment is the next stage!
>
> Regards
>
> Gerry in UK
Message 22
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| Subject: | Re: Electric Tail wheel tug |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:45 AM 8/2/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: "Paul McAllister"
><paul.mcallister@qia.net>
>
>Hi all,
>
>I know this is a little off topic but I am searching for mechanical
>components to construct an electric tail wheel tug. I need a small axle
>with a right angle drive similar to a differential. I have been searching
>the WEB but I end up with too many hits. I was thinking something from an
>electric wheel chair manufacturer might be able to be adapted. If anyone
>could suggest a few URL's to browse I'd appreciate it.
Consider modifying a small electric winch mechanism. Maybe
something from Harbor Freight? Most of the low cost, high
torque speed reducers take advantage of the one-step, high
mechanical advantage of a worm gear mechanism that might
offer both a motor and gearbox assembly suited to your
task.
Worm gears are horribly inefficient but in this application,
they might just be what you need.
Also check out the following offerings from ebay:
7534404208
7534284982
7704814350
7535764492
Bob . . .
Message 23
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| Subject: | Re: CAD software |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 06:47 AM 8/2/2005 +0100, you wrote:
>--> AeroElectric-List message posted by: "Steve Sampson"
><SSampson.SLN21@london.edu>
>
>Bob - before my machine crashed i had some simple software to read and
>modify Z-11 for instance. I had downloaded it from a reference on your web
>site. Cant find it now. Can you point me to the downloads.
http://www.aeroelectric.com/CD/AEC8_0.zip
Bob . . .
Message 24
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| Subject: | Re: Electric Tail wheel tug |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:38 AM 8/2/2005 -0500, you wrote:
>--> AeroElectric-List message posted by: Phil Birkelbach <phil@petrasoft.net>
>
>How 'bout a right angle drive for a drill?
>
>...or go to a pawn shop and buy a big angle grinder and gut it. I bet
>that gear box could take some abuse.
>
>I once knew a guy that built a tug to pull his Bonanza around out of a
>1/2" electric drill motor. You might also search around the hobby robot
>builders sites. They have good sources for stuff like this.
>
>Godspeed,
>
>Phil Birkelbach - Houston Texas
Great suggestions.
Bob . . .
Message 25
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| Subject: | Re: Electric Tail wheel tug |
--> AeroElectric-List message posted by: Dj Merrill <deej@thayer.dartmouth.edu>
Paul McAllister wrote:
> --> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net>
>
> Err, ahhh, Gerry who ?..... hang on I gotta go the nurse is coming
>
> do not archive
I think that was Gerry-atric or something like that... ;-)
do not archive
-Dj
--
Dj Merrill
Sportsman 2+2 Builder #7118
"TSA: Totally Screwing Aviation"
Message 26
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| Subject: | The fatwire ground blues . . . |
--> AeroElectric-List message posted by: <bakerocb@cox.net>
--> AeroElectric-List message previously posted by: "Robert L. Nuckolls,
III" <nuckollsr@cox.net>
>Comments/Questions: I am implementing your dual alt/batt/buss system on my
>GA-III. I fried a ground wire(lots of smoke)due to a loose battery ground
>connection while cranking the starter! The fried wire went to the fuel
>flow sensor mounted on the engine block. The starter return current tried
>to use the smaller wire due to a loose battery ground connector to the
>Alt-Battery. Should the sensors(Vision Micro) mounted on the engine block
>(fuel flow, fuel press, oil temp, oil press) have ground wires that
>connect to the engine block? These wires can be potential return paths for
>heavy starter current with a loose (-) battery connection.
8/2/2005
Hello Bob Nuckolls, I am concerned that your correspondent may have bigger
problems than just a fried wire. I quote from the Vision Microsystems
installation manual:
"DO NOT: ground the transducer body to any part of the aircraft, if
possible. Otherwise INSURE that the engine is EXTREMELY well grounded."
Emphasis provided by the author. The manual also contains specific
directions not to mount some of these transducers directly on the engine.
The wiring diagram for this system shows all wires (which are color coded)
from these transducers being connected to a specific pin in the DPU (Data
Processing Unit). I don't know how one could come up with a "ground wire" to
connect to the engine block.
It is possible that the DPU was damaged while the wire was being fried.
"When (before) all else fails ..... read the instructions".
OC
Message 27
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| Subject: | Re: Real data on OVP/etc (disinterested? DELETE) |
--> AeroElectric-List message posted by: "LarryRobertHelming" <lhelming@sigecom.net>
Well written and wow, what an effort to hold your punches Bob.
Indiana Larry, do not archive
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: AeroElectric-List: Re: Real data on OVP/etc (disinterested? DELETE)
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
>
> At 08:50 AM 7/28/2005 -0700, you wrote:
>
>>--> AeroElectric-List message posted by: "Paul Messinger"
>><paulm@olypen.com>
>>
>>Bob;
>>
>>Take a deep breath and read carefully and ignore any non technical parts
>>but
>>please consider the technical comments as worth considering as many are
>>industry wide technical info.
>>
>>Sorry for your upset
>
> I have never been more calm. There is ALMOST nothing you've stated
> in your writings here that are worthy of an emotional investment.
>
>> . . . but as usual you have missed my point and not addressed
>>MY technical issues in a technical manner, merely replied with a personal
>>assault (and perhaps properly deserved). There are some technical details
>>here in this post as you requested and some are a repeat of my much
>>earlier
>>posts, but I digress. Here is some of the data you asked for.
>
> <snip>
>
>>I am still waiting for ANY worst case design analysis showing any of your
>>designs is usable in all likely applications. Some of the possible false
>>tripping have been reported by buyers (not builders) of the OVP and all
>>who
>>contacted me wanted to remain anomalous (nor were they interested in a
>>refund), just a good approach to the design issue as Vans says to not use
>>any OVP design (yours or similar approaches).
>
> Which only illustrates the ignorance of our customers
> promulgated by your rhetoric and Van's equally ignorant
> advice. It may well be that those customers were experiencing
> the same difficulty that we discovered on the Bonanzas which
> we were happy to rectify for Raytheon and would have been
> equally happy to rectify for others except that they'd
> bought into a bill of goods that painted us as incompetent.
>
> The only case I was made privy to, the pilot MANUALLY SWITCHED
> the alternator on and off under load. It did not involve
> a nuisance trip. In fact, I doubt that ANY of the failures reported
> to Van involved real nuisance trips . . . but it's an easy thing
> for unhappy customers to improperly assign blame given some
> highly touted but mis-informed opinions being circulated.
>
>> As we have no info on the sold
>>OVP design, its not possible to accept your statement that only the
>>builders
>>versions are at fault. I for one wonder why the sold version would be any
>>different schematically.
>
> For very good reasons which I would have provided if you
> had asked. The sold versions are the same DIY version of
> some years ago before the MBS4991 went obsolete. B&C did
> a lifetime buy of the part to continue production of that
> design but we needed another approach for the DIY circuit (which was
> built, tested, qualified and incorporated into some production
> units - except for the toe stubber that Ken pointed out
> earlier this week).
>
>
>>You have suggested many times that somehow the Vans rebuilt alternators
>>have
>>poor quality regulators and that is why they fail at a extremely hi rate
>>when used with your OVP. From what little data I could find its a failure
>>rate of 10% or much higher. Clearly something unique in the application of
>>the wiring in Vans designs or ????? Some were purchased OVP and not built
>>up
>>units.
>
> It was a hypothesis . . . .do you have another? But let's not
> mix apples and oranges. The style of OVP has nothing to do
> with the failures of Van's alternator. The very act of switching
> the alternator OFF while loaded seems to be the trigger event.
> This happens whether it's an ov trip from a crowbar module, Eric's
> OVP module, or simply operating the switch on the panel. I'm
> certain that it's a load-dump event that kills the alternator's
> own regulator.
>
> This is an issue SEPARATE from and not affected by style of OV
> protection.
>
>
>>"Rebuilt" alternators is really a false name in the industry. They are
>>only
>>repaired (what is failed is replaced, what still works is not replaced)
>>and
>>the ND 60 amp unit has been around for at least 25 years. Many units have
>>been "rebuilt" several times. I contacted several major rebuilders around
>>the country (including Bosch) as well as a couple of local ones and found
>>no
>>one replaces anything still working. Not even bearings were normally
>>replaced in some cases. Thus a "new rebuilt" alternator might have an
>>original 25 year old regulator or a cheep low quality import replacement
>>or
>>a modern but still low cost replacement. None admitted they used OEM (ND)
>>regulators as replacements. The typical reply was "price competition"
>>prevented that approach. Thus its not possible to single out Vans as
>>having
>>poorer alternators than others.
>>
>>The comments that in affect state my OVP is not the problem its Vans low
>>quality rebuilds is what is upsetting. (MY S%&T does not smell :-) )
>
> I've never said that my design could not have been root
> cause of failures in Van's alternators due to any
> particularly "golden" design. What I said was that Van's
> alternators were failing because they were being unloaded
> by mis-use of switches to control the alternator that were
> PART of the ov system . . . the same damage would have
> happened irrespective of who's ov module was used . . . or even
> if no ov module is included in the b-lead control concept.
>
> Eric currently publishes an ov protection scheme utilizing
> the Killovac contactor which will fix the contactor performance
> issue . . . but guess what? It will still kill alternators
> for exactly the same reasons as before.
>
>
>>Then I contacted a design engineer in the semi industry responsible for
>>the
>>modern one-chip regulator (not the one used by ND) and described the
>>problem
>>we were having. The reply was the design would protect against the normal
>>load dump but was unlikely to survive a contactor contact arcing and the
>>opening a loaded output "B" lead. This agrees with several different
>>automotive test requirements for alternator design testing. The industry
>>is
>>designing to the automotive equivalent of the aircraft DO-160 which is
>>more
>>severe.
>>
>>At present the only known reasonably priced contactor RATED to open the
>>"B"
>>lead is the Kilovac. The common contactors available are not rated to open
>>the voltages likely to be found under fault conditions.
>
> Agreed. Which address only ONE issue. Contactor performance
> as a b-lead controller. It has no bearing on either style
> of ov protection used or on failures of alternators due to
> load-dumping.
>
>
>>I quote from a major relay manufacturers web site for contact application.
>>
>> "Improper or excessive suppression can cause the relay to suffer from a
>>long release time, slow contact transfer, and contact bounce on break. All
>>of these conditions will increase contact arcing when load switching,
>>which
>>will reduce relay life dramatically.".
>>
>>One site http://relays.tycoelectronics.com/kilovac/appnotes/transients.stm
>>goes on to compare six different methods of coil "spike suppression" Its
>>interesting to read this table and see that the common diode is the LAST
>>choice and the Bi directional Zener (read bi directional transorb). There
>>are similar tables in the USA and Europe and ALL suggest the last method
>>of
>>choice is the simple diode. The simple diode works as long as the contacts
>>are carrying low currents and non inductive loads. In the case of the
>>alternator its a very different matter as the unloaded unregulated
>>alternator voltage can jump to hundreds of volts during the contact
>>bouncing
>>during opening even with the best coil suppression method thus the need
>>for
>>the Kilovac which is rated at hundreds of volts.
>
> This is yet another isolated issue that goes toward potential slowing
> of contact spreading velocity during opening. I've done extensive
> testing and published results that show marked DELAY in contact opening
> but not a significant slowing of spreading velocity. Tendencies to arc
> during opening were exactly the same whether one used no diode,
> a bi-directional Transorb or a plain diode.
>
> If one is worried about opening delay, the Transorb is the way to
> go. If one is concerned about best life for the controlling switch,
> the diode is the best way to go. Since my designs didn't care about
> delay time, I opted to stay with diodes.
>
> See exemplar test plots representative of lots of tests on a variety
> of relays and contactors:
>
> http://www.aeroelectric.com/Pictures/704-1DelayNoDiode.gif
> http://www.aeroelectric.com/Pictures/704-1DelayWithDiode.gif
>
> http://www.aeroelectric.com/Pictures/704-1OpeningTimeNoDiode.gif
> http://www.aeroelectric.com/Pictures/704-1OpeningTimeWithDiode.gif
>
>
>>I find the use of the simple diode across relay contacts one of the most
>>widespread miss information in the industry. IF ""Joe"" does it, it must
>>be
>>OK ,or if it was not good why are relays available with one built in?.
>>It's
>>very simple engineers are lazy and copy what others do far too often. Also
>>it works in 99.9% of the cases. It does not work in a "B" lead contactor
>>application however. Manufacturers will build what the engineers want
>>regardless of its design value.
>
> How is it mis-information if testing is used to deduce and
> select from one of several controlling features? When diodes
> were FIRST placed across the contactor coils in mid 60's, Transorbs
> were not around . . . although we COULD have applied a variety
> of spike snubbing techniques such as resistors or resistor-capacitor
> networks.
>
> The plain diode was used for decades across coil contactors
> with great success for eliminating arc-induced wear on
> controlling switches. Now comes the folks who are sifting the
> grains of sand looking for the next quantum jump in relay/contactor
> performance and the new kid on the block (Transorb) offers yet
> another opportunity for improvement.
>
> The question not asked and answered is: Do contactors and relays
> in light aircraft operated enough cycles per hour, month, year
> or even lifetime of the airplane for there to be even a measurable
> improvement in service life of the device? A battery contactor
> operates very lightly loaded and into a largely resistive load
> and only once per flight cycle. Perhaps 50-100 times per YEAR
> in a SE light aircraft. Starter contactors get the crap kicked
> out of them once every flight cycle . . . which is why they're
> specifically designed to take this extraordinary abuse. In BOTH
> cases, use of a diode across the coil provides the same demonstrable
> benefits for increasing life of the controlling switch since
> we "discovered" them in 1965.
>
> I'm not for a moment suggesting that substituting Transorbs for
> diodes is a bad thing to do . . . but I object to any inferences
> that my suggestions that diodes are "okay" is a promulgation of
> "mis-information." I've been to the workbench, got out the test
> equipment and demonstrated to my satisfaction that there is
> no value in promoting Transorbs over diodes for the ways I
> show them in my drawings.
>
>>I have demonstrated this in my testing and I suspect its repeatable by you
>>if you use a common contactor from Wicks for example. The contactor I used
>>was from Wicks. In one case the bounce duration was quite long and
>>included
>>many bounces.
>
> Opening bounce? I'm having trouble visualizing how contacts initially
> moving apart reverse direction and move back together. What's the
> forcing function? Bounce on closure is predictable and understandable.
> I'd really like to repeat your experiment here too . . . please
> show us the setup.
>
>
>>My conclusion is never use a "rebuilt" internally regulated alternator
>>with
>>ANY OVP device that might false trip or trigger on a short transient.
>
> This doesn't compute. Adding ANY form of b-lead control to ANY
> internally regulated alternator is an adventure into unknown risk.
> It has nothing to do with style of ov protective devices . . . false
> tripping or otherwise. If one subscribes to the paradigm of being able
> to CONTROL one's engine driven power source from the panel, then we
> agree that a b-lead contactor is called for in every installation of
> an internally regulated alternator.
>
> Now, there is RISK that the alternator can be damaged by simply
> turning it OFF while loaded whether the system included OV protection
> or not.
>
>> With
>>a brand new ND alternator available for $300+ and the demonstrated failure
>>rate in the auto industry being so low its unlikely any of us will ever
>>see
>>a "fail hi" condition in a lifetime of flight. Van does not recommend any
>>OVP and with a modern regulator I agree its addition only reduces system
>>reliability. The Fail HI mode of regulator failure is a very low
>>probability in the failure modes of the modern regulator . Any failure of
>>any type is extremely low in today's new production ND alternators.
>
> Low . . . but not zero. Recall Jack's post of just last week:
> --------------------------------
>
> --> AeroElectric-List message posted by: "Jack Eckdahl"
> <jeckdahl@sjrwmd.com>
>
> George: The alternator that failed was a nippon denso, 60 amp,
> internally regulated. I'm not sure that my experience should cause
> others to avoid this unit. I know that hundreds of airplanes are flying
> successfully with them. However, if you read Bob's most recent post,
> you might decide to avoid all internal regulated alternators.
> Bob: As soon as I pull the fuel guage, I'll send it too you. What
> address? thanks, jack
>
> ---------------------------------
>
>
>>Use of any OVP has the potential of failing the alternator when it trips
>>for
>>what ever reason so IF a OVP is used it needs to be extremely reliable
>>under
>>all design conditions. It should never trip unless the OV is clearly of
>>long
>>duration. The AEC OVP device trips in a few milliseconds and really should
>>not trip unless the OV is longer than what one might expect from a major
>>load dump.
>
> Agreed. But here you're substituting your design goals without
> regard to the goals of our customers (who cited DO160/MS704) when
> time constants were selected for the ov trip dynamics. The nuisance
> tripping we've experienced has NOTHING to do with the OV sense
> circuit and everything to do with dv/dt sensitivities of the SCR
> which has shown that there are antagonistic events in SOME
> systems that are NOT suggest by DO160/MS704.
>
> After our epiphany, we made adjustments to the circuit for all
> new production and for anyone who was plagued with the condition
> in the field at no charge. This is a DISCOVERY of a phenomenon
> not previously considered (by industry standard practices). No
> amount of analysis would have predicted the condition we were
> told did not exist (or at least was not previously identified).
> The new requirement did not come to light until the Bonanza
> production line produced a series of REPEATABLE EXPERIMENTS
> critical to identification of root cause and deduction of remedies.
>
>
>>YOU agreed there were cases of false tripping yet you failed to properly
>>analyze your design. There was absolutely no reason for a real lab test
>>and,
>>in fact testing was a near total waste of time, as the false tripping
>>depends on a specific implementation of the classic schematic. How do you
>>expect to build all variations of a schematic??
>
> You cite facts not in evidence. EVERY instance of a customer
> reporting a nuisance trip problem has been dealt with in
> a positive way if they only came forward with their
> complaint. Just a few days ago, I upgraded an OV module
> that worked as advertised for 4 years but became irritated
> by a new accessory in the airplane.
>
> We DID analyze the design, deduced modifications to fix the
> problem, and offered the fix to anyone who needed/wanted it
> at no charge.
>
>
>>How can there be repeatable tests when several major components have
>>important design tolerances or variables in the 5x or 10x range of
>>tolerances. Battery internal resistances of 5-1 or more, CB resistances of
>>10-1 or more. Schematic is one thing wiring diagram is another (how a
>>schematic is implemented and where wires are connected along a common line
>>in a schematic can and often does greatly affect the results.
>
> I've given you the data that supports both my analysis and
> test results. You still haven't told me what breaker you've
> tested where the manufacturer says it goes tits-up on a 50x
> overload.
>
>
>>The time tested and standard method of circuit analysis is on paper with
>>or
>>without the help of software;
>
> <snip>
>
>> However the use of PC625 and the very similar PC680 are very popular
>>around here as are the use of dual batteries often simple wired directly
>>in
>>parallel.
>
> The batteries are not the controlling factor. Wiring and breaker
> resistances are. Lets assume ZERO battery resistance but we still
> have 0.04 ohms of breaker resistance and a couple of feet of
> 20AWG wire for another .04 ohms when combined with a 2v drop
> across the SCR yields about 130 amps of crowbar current. If it
> would make you feel better, we COULD add the admonition to our
> installation manuals not to install the crowbar module or any
> of the LR series regulators with zero length wires . . . but given
> that most folks locate their equipment some distance from the
> bus, that worry wasn't high on our list of concerns.
>
>
>>You used 0.035 ohms for the CB and got trip times of a few MS. I used a CB
>>from Wicks and measures it at 0.003 ohms and it tripped repeatetly in the
>>50-70 ms range. Yes the data seems illogical but my data is repeatable
>>here
>>and I accept your data also as factual.
>
> What was the brand and part number of this .003 ohm breaker?
> Results you're reporting are so astounding that they
> BEG for a repeated experiment. Please afford me the courtesy
> of knowing how to do it.
>
> I've uploaded data sheets on breakers I find in Wicks catalog
> to
>
> http://www.aeroelectric.com/Mfgr_Data/Breakers/Potter_Brumfield
>
> The two P&B data sheets speaks of 0.030 +/-30% for max
> breaker resistance on 5A breaker. Of course, this is a MAX
> value. Did you find an exemplar breaker that presented a
> resistance 1/10th this value?
>
> I'm amazed that one can fabricate a 5A breaker heater with so
> small a resistance. I've measured dozens of breakers by Woods,
> Mechanical Products, Klixon, and Eaton-CH and they all agree with
> their data sheets to present about 30-40 milliohms of series
> resistance
> in a 5A breaker. Smaller breakers are markedly higher in resistance.
>
>
>>There is no way you can reproduce my test data unless you use the exact
>>same
>>parts.
>
> ABSOLUTELY! DEAD ON! By the same token, I cannot evaluate
> the validity of your test data without knowing what parts you
> used. You keep hammering me with these near zero-ohm breaker
> values and I can't find anything approaching these values
> in any products I can put my hands on.
>
>>This is the fallacy of your requirements that the test must be
>>reproducible by you to be valid.
>
> ???? Paul, this is a truly astounding statement from someone
> to claims to be an engineer. No sir! For CLAIMS made by
> ANALYSIS of test results to be valid, they should be
> CAPABLE of being repeated by anyone who wishes to do
> the work. OF COURSE this requires a complete disclosure
> of all materials and techniques used. Remember the cold fusion
> guys of about 15 years ago? They made claims that begged
> critical review by repeated experiment. Remember Dave Blanton's
> 240 hp, 6-cyl Ford conversions? How about Jim Bede's super-sonic
> OBAM product? Geesh! Just watch late night TV and you'll get
> tons of information most of which would not stand up to
> critical design review and repeated experiments. But the gullible
> consumer is not privy to real data or experience that validates
> the propagandist's claims. You might as well be watching a
> Siegfried and Roy show and believing those lions really disappear.
> Until they show me how I can make lions disappear, it's nothing
> but propaganda with an agenda. In their case, the agenda is
> is entertainment which I do enjoy. What's your agenda sir?
>
> Data for repeatable tests are a COURTESY that REAL scientists
> offer each other as and AID to investigating any phenomenon.
> I expected and requested no more of you and I was fully transparent
> in everything I used to base my claims. I've built a career
> on repeatable test results in the lab and in my customer's
> airplanes. Yes, things slip by sometimes - the only thing
> we can do then is act in a responsible way to rectify
> the problems as they arise.
>
>>Perhaps its valid where the circuit
>>variables are not so dependent on individual parts used but in this case
>>the
>>parts variation is so huge they prevent repeatable tests. Both tests are
>>reasonable examples of the overall design as documented on your web site
>>and
>>neither are a worst case example as only a proper analysis can define the
>>range of design results.
>>
>>ANY design that is to be reproduced must be analyzed using the specified
>>data sheet parts variations (and either specify the exact parts of
>>consider
>>all the likely parts brands that could apply) and for general use NEVER
>>publish a design that violates the data sheet under any condition or
>>assumes
>>parameters not specifically printed in the data sheet.
>
> Pleeeasssss, purdy pleeeaasse, show me the data sheets.
>
>
>>In any event I see no reason to continue posting.
>
> That's fine too.
>
> I sat in a meeting yesterday for several hours looking at about 50
> pounds of paper on the table that included failure mode effects
> analysis, reliability studies that assured us we were buying
> a 7,000 hour MTBF product, test reports out the wazzoo,
> detailed worst case analysis, etc. etc. These papers
> presumably defined a system that we paid $millions$ for and
> according to all the analysis, should be the golden product.
>
> It won't run more than 10 hours without annunciating a failure
> and causing our customers great concern and billing our coffers
> many $killo$ of warranty csots. This golden system monitors
> dozens of potential problem areas and if you believe the
> marketing hype (we did) . . . it's the safest system ever to
> fly.
>
> Problem is, the designers forgot to offer a way to tell which
> one of 5 dozen faults tripped out the system. Further, as far
> as the FAA is concerned, the system is blessed (it passed all
> the qual tests) and is carved in stone. Any changes (to
> upgrade performance or to even fix simple nuisance trips) are
> horrifically expensive and time consuming to implement.
>
> I have a proven, flight-tested alternative system that has run fault
> free for hundreds of hours. The system that works was afforded
> perhaps 5% of the analysis and testing compared to the system that
> doesn't work. Further, ALL operating characteristics of the
> working system are observable at any time . . . INCLUDING
> those characteristics that might produce shut downs.
>
> If you want to apply the tools of detailed analysis to
> the crowbar (or any other) ov protection system, you
> must first cite ALL sources, magnitudes and configuration
> of your hypotheticals. Only then may we debate results to your
> heart's content as scientists. Analysis is a tool. It depends
> on proper application of good input data and lucid interpretation
> of results. These things are BEST conducted as cooperative
> critical reviews where everyone's focus is on doing the
> best thing for our customers and students and not lobbing
> cabbages.
>
> Now, HERE is where I DO get tense . . .
>
> I'll continue to object to your rhetorical, unfounded
> attacks on "my approach" when I'm the one who has thousands
> of happy customers. The few secret, unhappiest customers are
> those who accepted your hip-shot assessment of my engineering
> integrity and business ethics to the extent that they (according to
> you) won't take advantage of remedies I'm begging to offer. Further,
> you have deprived ME of benefits for having field experience upon
> which to deduce root cause of problems and to craft improvements
> to my products and servics.
>
> One of the KEY attributes of our society that served to build
> us into an economic powerhouse in record time is that sacred
> relationship between honorable suppliers and consumers who
> walk away from every deal happy or at least free of fraud
> or encroachment on their property.
>
> How many times on this List have I encouraged individuals
> with questions or complaints about any product to communicate
> FIRST with the manufacturer/supplier? Give the supplier
> an opportunity to do the right thing and support their
> customers to the best of their ability and/or business model.
>
> You have injected yourself into the relationship between
> me and individuals who have invested in my goods or services.
> Your actions, no matter how well intended, are costing me
> undeserved loss of both good-will in the marketplace and valuable
> feedback from my customers. Your actions have produced unhappy
> customers AND suppliers through no fault of either. There are
> no civil words in my vocabulary to adequately express how much
> this displeases me.
>
> If you do post, show me the data. If you choose not to post,
> I wish you well but I'll continue to worry about your crusades
> against myself (and probably others) who are not deserving of your
> dishonorable disservice.
>
> Bob. . .
>
>
>
Message 28
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| Subject: | Fw: CAD software |
--> AeroElectric-List message posted by: "Steve Sampson" <SSampson.SLN21@london.edu>
----- Original Message -----
From: Steve Sampson
Subject: CAD software
Bob - before my machine crashed i had some simple software to read and modify Z-11
for instance. I had downloaded it from a reference on your web site. Cant
find it now. Can you point me to the downloads.
Thanks, Steve.
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