Today's Message Index:
----------------------
1. 06:28 AM - Re: Hypothetical Battery Contactor Failure (racerjerry)
2. 06:43 AM - Re: Hypothetical Battery Contactor Failure (user9253)
3. 07:56 AM - Re: Bendix King KY97A Tuning Problem (racerjerry)
4. 08:50 AM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III)
5. 03:20 PM - Re: Hypothetical Battery Contactor Failure (user9253)
6. 05:32 PM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III)
7. 05:35 PM - Composite Aircraft and Lightning Strikes (William Hunter)
8. 06:26 PM - Re: Re: Hypothetical Battery Contactor Failure (Charlie England)
9. 08:44 PM - Re: Composite Aircraft and Lightning Strikes (Robert L. Nuckolls, III)
10. 08:52 PM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III)
11. 09:36 PM - Re: Hypothetical Battery Contactor Failure (user9253)
12. 10:20 PM - Re: Re: Hypothetical Battery Contactor Failure (Robert L. Nuckolls, III)
13. 11:43 PM - Re: Composite Aircraft and Lightning Strikes (Peter Pengilly)
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Subject: | Re: Hypothetical Battery Contactor Failure |
On a simple aircraft such as my Cessna 172K, the voltage regulator "S" terminal
is supplied with power through the battery contactor. If no power is present
at the voltage regulator, the alternator field SHOULD not be energized rendering
the alternator inoperative. The first noticeable indication after battery
voltage bleeds down is that my VHF radio display (KX-155) goes blank.
In order to alert me to take necessary steps to conserve battery power after an
alternator failure, I installed a "13V Idiot Light" from Perihelion Design, which
I highly recommend. Only $50 and legally installed without paperwork using
Velcro and powered through cigar lighter. In addition, I added a Westach 6-16
VDC voltmeter to give me a REAL indication instead of the near worthless
ammeter.
--------
Jerry King
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=457550#457550
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Subject: | Re: Hypothetical Battery Contactor Failure |
Once an engine is running above idle, the battery no longer supplies electrical
power to the aircraft. The alternator does. Many alternators will continue
to operate if the battery is then disconnected. The electrical current needed
to power the alternator field comes from the alternator output, whether the battery
is connected or not. There may be some alternators that will not continue
to run without a battery connected. Even for alternators that do continue
to operate without a battery, the alternator could stop working if a very large
electrical load is turned on which causes the system voltage to momentarily
drop.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=457555#457555
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Subject: | Re: Bendix King KY97A Tuning Problem |
I am sure you know this already BUT... Before you tear it apart, make sure the
problem is not just a loose knob set screw
--------
Jerry King
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=457561#457561
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Subject: | Re: Hypothetical Battery Contactor Failure |
At 08:13 AM 6/30/2016, you wrote:
>
>Once an engine is running above idle, the battery no longer supplies
>electrical power to the aircraft. The alternator does. Many
>alternators will continue to operate if the battery is then
>disconnected. The electrical current needed to power the alternator
>field comes from the alternator output, whether the battery is
>connected or not. There may be some alternators that will not
>continue to run without a battery connected. Even for alternators
>that do continue to operate without a battery, the alternator could
>stop working if a very large electrical load is turned on which
>causes the system voltage to momentarily drop.
WWWaaaayyyy back when, it was generally
assumed that running the aircraft sans battery
was not a good thing to do. Before alternators,
generator and battery switches were separate
and generators would self-excite. Given that
batteries are NOT good filters of power
generation noise, it didn't matter if the
battery was on-line or not.
The earliest alternators on Cessnas (and indeed
all other S.E. TC aircraft) were automotive
derivatives. I was not privy to any investigative
tests at Cessna but the corporate policy was
that their airplanes should not be operated
sans battery. Hence, the split rocker switch
was birthed.
Apparently, Beech experience was different. While
many if not most of the smaller S.E. aircraft
did the same battery-first-then-alternator
switching protocol. Re: B-23 Sundowner panel
excerpt below . . .
Emacs!
The Bonanza and Barons were different. The first
regulator design I qualified for Beech was about 1978 and
their procurement specification stated that no feature
of the regulator's circuitry 'shall prevent the alternator
from coming up self-excited above xxxx rpm". This was
the first time I'd encountered an alternator EXPECTED to
come up all by itself. The Bonanza and Barons had totally
independent battery and alternator switches. Operation
sans battery was not prohibited and in fact the system
was designed to allow it.
I've got a new electro-mechanical test bench under
fabrication and will be doing some work on PM Dynamo
rectifier/regulators. The same facility will allow me
to explore and quantify the present state of the art
in production alternators. In the mean time, as long
as you don't hit the alternator with a really BIG load
(which few system are capable of doing anyhow), the
modern alternator runs self-excited and benefits immeasurably
from battery presence with respect to noise. More
details to follow.
So the answer to the opening question on this thread is:
"Loss of the battery contactor in flight will not
produce a behavior likely to be noticed in the air."
Bob . . .
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Subject: | Re: Hypothetical Battery Contactor Failure |
Thanks for the knowledgeable answer. Once your new test bench is up and running,
it would be interesting to verify or disprove this statement quoted from the
Rotax 912 Installation Manual,
> Never sever connection between terminal C and B of regulator (e.g. by removal
of a fuse) while the engine is running. Overvoltage and regulator damage can
occur.
I find that statement hard to believe. When voltage is removed from Rotax regulator
terminal C, its DC output should shut off, not increase. Of course the
AC voltage would increase due to lack of load, but not anymore than if all electrical
loads were shut off.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=457567#457567
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Subject: | Re: Hypothetical Battery Contactor Failure |
At 04:20 PM 6/30/2016, you wrote:
>
>Thanks for the knowledgeable answer. Once your new test bench is up
>and running, it would be interesting to verify or disprove this
>statement quoted from the Rotax 912 Installation Manual,
>
> > Never sever connection between terminal C and B of regulator
> (e.g. by removal of a fuse) while the engine is running.
> Overvoltage and regulator damage can occur.
If we had a VERIFIED copy of the schematic
for the Ducatti R/R, the validity of that
statement could be confirmed or debunked.
I have seen THIS schematic offered from various
sources over the years
http://tinyurl.com/zfkte7c
A simply analysis of this drawing demonstrates
that "C" is both the voltage regulation sense
lead -AND- power source for the low-level
regulating circuity. Simple analysis of this
schematic shows that disconnection of the C
terminal causes the R/R to shut down . . . which
is consistent with a legacy design philosophy for
voltage regulators of all stripe.
>I find that statement hard to believe. When voltage is removed from
>Rotax regulator terminal C, its DC output should shut off, not
>increase. Of course the AC voltage would increase due to lack of
>load, but not anymore than if all electrical loads were shut off.
This is an enduring problem with anecdotal
data gleaned from the catacombs of hangar-lore.
Open circuit voltage from the PM dynamo windings
may indeed be the voltage referred to by the
original assertions. Further, THAT voltage
generated by the engine running cruise rpm
just might be hazardous to the R/R . . . but
without the benefit of original designers
documentation, we might as well be discussing
Slobovian politics over a pitcher of beer.
In the TC world, we write specs, do test plans,
carry out experiments in the lab and airplanes on
the ground and airborne. Then we write test
reports which form the foundation for design
decisions or remedial actions to correct a deficiency.
Without that report (assuming one was ever produced)
the real meaning of the ideas floating around on
forums and hangars are at risk for (1) being mis-
interpreted and (2) being morphed with the telling
and re-telling into an entirely new significance.
If the FAA ever extends it's grip deeper into
OBAM aviation, a very strong excused is bound
to include our poor utilization of computing
and communications tools to keep (1) and (2)
in check.
So I'm with you my friend. I think the assertion
about the Rotax R/R is at best an idea that
suffered too many re-tellings by individuals
with little or no understanding.
Bob . . .
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Subject: | Composite Aircraft and Lightning Strikes |
Hi All,
There is a discussion brewing on the Velocity Owners Builders Association
about composite aircraft and lightning strikes.
What sparked (sorry) this discussion was a question about static wicks and
if they could be useful on composite aircraft and now there is some good
bantering going on about lightning strikes and composite
aircraft...so...naturally I thought since there is some really sharp
electrical folks on this forum I would ask you all for your feedback on the
subject and I will certainly give you credit for your feedback and
suggestions (of course I could not try to pass this knowledge off as being
my own because that cat is already out of the bag and they would never
believe it came from me).
Anyhoo...here are some questions (if you think up others please feel free to
add):
-Would static wicks be beneficial to add to a composite aircraft?
-If adding static wicks to a composite airplane, where should they be added?
-Should control surfaces be bonded to the aircraft structure if static wicks
are used (and even if static wicks are not used)?
-Should all of the metal components of the aircraft be bonded together and
if so what technique should be employed to do so?
-Does anyone know of any lightning strike incidents to composite aircraft
and if so what damage to the aircraft structure/components have occurred?
-What causes lightning to be attracted to airplanes and/or why does
lightning hit airplanes (yes, I can understand why lightning hits
trees/buildings/other items that are connected to earth but an airplane is
not connected to earth...if it had just taken off I could see the static in
the wake leading to ground however an airplane in cruise flight is another
story)?
-Are composite aircraft more or less likely to be hit by lightning than
metal airplanes?
-Are there any techniques or design considerations that would mitigate the
chance of lightning strikes on the composite aircraft and/or the damage
being done should the aircraft be hit?
-On production composite aircraft, what if any equipment/design
considerations have been required by the FAA to be employed in reducing the
chances of and/or in mitigating the effect of a lightning strike?
-Some guys are discussing using Carbon Fiber or mesh being installed under
the surfaces of the airplane to transfer the energy of a lightning strike so
if a mesh of some sort is indeed used, will it help or hurt in reducing the
chances of and/or in mitigating the effect of a lightning strike (if the
mesh is not robust enough to conduct the extreme electrical current by a
lightning strike could it make the problem worse (as a lightning rod on a
house has a too small conductor then the lightning rod attracts the
lightning and then once the lightning does actually hit the rod the
conductor to ground melts and now the house structure becomes the conduit to
ground)?
Please dream up other thoughts in the area of lightning strikes and I will
certainly forward them on.
We appreciate your help in making the design of the Velocity aircraft more
safe during this time of year!!!
..
Cheers!!!
Bill Hunter
Message 8
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Subject: | Re: Hypothetical Battery Contactor Failure |
On 6/30/2016 4:20 PM, user9253 wrote:
>
> Thanks for the knowledgeable answer. Once your new test bench is up and running,
it would be interesting to verify or disprove this statement quoted from
the Rotax 912 Installation Manual,
>
>> Never sever connection between terminal C and B of regulator (e.g. by removal
of a fuse) while the engine is running. Overvoltage and regulator damage can
occur.
> I find that statement hard to believe. When voltage is removed from Rotax regulator
terminal C, its DC output should shut off, not increase. Of course the
AC voltage would increase due to lack of load, but not anymore than if all electrical
loads were shut off.
>
> --------
> Joe Gores
>
I don't know squat about Rotax stuff or their manual, but...
If it's a PM style alternator, and the regulator is a shunt style
regulator, and breaking that C-B connection removes the shunt load, then
I can see how the regulator might be damaged. If the regulator
sensing/control semiconductors are still connected to the alternator
output but the shunt *isn't*, then the alternator could well be able to
create a high enough voltage to exceed the max voltage ratings of the
devices.
Having the shunt *in* the circuit would ensure that the voltage never
got that high.
Charlie
Message 9
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Subject: | Re: Composite Aircraft and Lightning Strikes |
>
>Anyhoo...here are some questions (if you think up others please feel free to
>add):
>
>-Would static wicks be beneficial to add to a composite aircraft?
Depends. A 'static wick' is intended to REDUCE coronal
resistance between CONDUCTIVE parts of the airframe and
the surrounding atmosphere. Without static wicks, electro
static potentials in the millions of volts can build up
in various places on the airframe. The existance of
high levels of static build up can manifest in (1) visible
light (St. Elmo's Fire on prop tips, around window frames,
sharp trailing edges), (2) radio noise that can totally
cripple some systems and sometimes (3) excessive erosion.
The purpose of a static wick is to ENCOURAGE dissipation of
electro-static energies at LOW levels . . . levels too low
to produce the deleterious effects cited.
-If adding static wicks to a composite airplane, where should
they be added?
EXCELLENT question. Figuring out were to put them nn a metal
airplane is not a simple task . . . an insulated airplne is
whole different ball game.
I've seen airplanes perched on insulating jacks and excited
with bunches of volts while a technician walks around the outside
probing potential leak-off points on the airframe with a very
long test probe. This is a good start on figuring out where
potentially
>-Should control surfaces be bonded to the aircraft structure if static wicks
>are used (and even if static wicks are not used)?
>
>-Should all of the metal components of the aircraft be bonded together and
>if so what technique should be employed to do so?
Can't think of a single reason to do such things.
I think Burt Rutan may have uttered such an opinion
WAaaayyyy back when about control surfaces on the Ez
series aircraft . . . But I'm at a lost to imagine, much
less demonstrate how the action would benefit anything.
>-Does anyone know of any lightning strike incidents to composite aircraft
>and if so what damage to the aircraft structure/components have occurred?
One of our very own suffered just such an event
http://tinyurl.com/hre2hkz
>-What causes lightning to be attracted to airplanes and/or why does
>lightning hit airplanes (yes, I can understand why lightning hits
>trees/buildings/other items that are connected to earth but an airplane is
>not connected to earth...if it had just taken off I could see the static in
>the wake leading to ground however an airplane in cruise flight is another
>story)?
>
>-Are composite aircraft more or less likely to be hit by lightning than
>metal airplanes?
Intuitively one might think so . . . but the airplane
is only a triggering influence in what was going to
be a strike whether the airplane was there or not.
All images of airplanes being struck show the airplane
in the middle of a strike that extends from one
area of the storm (usually cloud) to another area
or the ground.
>-Are there any techniques or design considerations that would mitigate the
>chance of lightning strikes on the composite aircraft and/or the damage
>being done should the aircraft be hit?
Yeah, it's called staying the @#$@ away from
areas for which no practical invincability can
be demonstrated. This included lightning, ice,
high winds, hail, etc.
>-On production composite aircraft, what if any equipment/design
>considerations have been required by the FAA to be employed in reducing the
>chances of and/or in mitigating the effect of a lightning strike?
It's exaclty the OPPOSITE. We cannot nor do we attempt
to avoid being struck. We must ASSUME we WILL be struck
and design for measured and predicted stresses.
>-Some guys are discussing using Carbon Fiber or mesh being installed under
>the surfaces of the airplane to transfer the energy of a lightning strike so
>if a mesh of some sort is indeed used, will it help or hurt in reducing the
>chances of and/or in mitigating the effect of a lightning strike (if the
>mesh is not robust enough to conduct the extreme electrical current by a
>lightning strike could it make the problem worse (as a lightning rod on a
>house has a too small conductor then the lightning rod attracts the
>lightning and then once the lightning does actually hit the rod the
>conductor to ground melts and now the house structure becomes the conduit to
>ground)?
Check with the Lancair and Glasair forums. These folks
would come a close as anyone to knowing what was tried
and either succeeded or failed to produce the desired
mitigation of effects. There is a wealth of discussion
on . . .
http://tinyurl.com/zeay3x5
. . . this is NOT a trivial task.
>Please dream up other thoughts in the area of lightning strikes and I will
>certainly forward them on.
>
>We appreciate your help in making the design of the Velocity aircraft more
>safe during this time of year!!!
History is rife with examples of work done
to make aircraft resistant to the effects of
lightning strike. Lancair, Glassair and contemporaries
wrestled with it. At Beech, we stayed with metal wings
but the fuselage structures have large, flat conductive
straps that run longitudinaly7 in the fuselage. These
'fixes' are tested in direct effects of lightning laboratories
to show that people, structure and systems within the airplane
remain intact after events that are ASSUMED WILL HAPPEN.
The simple answer to the question is: "Yes, you CAN do things
to airplanes of any stripe to reduce risk due to lightning
strike . . . but it's not a simple task. A task deeply intertwined
with issues of structural integrity, weight, aerodynamics . . . and cost.
In flight school, we were well advised to stay away from
ice and convective activity. Risks to body and airframe go
up exponentially . . . while costs for mitigation of those
risks are breathtaking.
Adding any feature intended to mitigate environmental
risk brings some human factor's issues with it. More that
one pilot with boots, prop-deice and a windshield heater
patch was willing to 'press on just a little further' . . .
with more than simply disappointing outcome. The same
effect could beset a pilot flying an airplane with
lightning mitigation enhancements . . . enhancements
that did not benefit from a through checkout in the
lightning lab by folks who have been there, done that.
Bob . . .
Message 10
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Subject: | Re: Hypothetical Battery Contactor Failure |
>If it's a PM style alternator, and the regulator is a shunt style
>regulator, and breaking that C-B connection removes the shunt load,
>then I can see how the regulator might be damaged. If the regulator
>sensing/control semiconductors are still connected to the alternator
>output but the shunt *isn't*, then the alternator could well be able
>to create a high enough voltage to exceed the max voltage ratings of
>the devices.
Nobody has built a shunt style regulator in
a very long time. A few small systems on motor
bikes and snowmobiles popularized the simple
design but the B&C regulators have never been
shunt . . . the alleged schematic of the Ducatti
R/R is also a series regulator.
They are manufactured as a spares item but better
regulators are so easy to design, there's no reason
to stay with shunt style.
>Having the shunt *in* the circuit would ensure that the voltage
>never got that high.
but it WOULD drive internal energy dissipation
to the max and, give the demonstrably poor
thermal management of many designs, could
toast the device. But I'm pretty sure
nobody builds/offers that control philosophy to
on the product we're using.
Bob . . .
Message 11
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Subject: | Re: Hypothetical Battery Contactor Failure |
The Rotax (Ducati) rectifier/regulator is a switching-power-supply type of regulator
that turns on for part of the dynamo AC cycle. There is no shunt.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=457572#457572
Message 12
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Subject: | Re: Hypothetical Battery Contactor Failure |
>If it's a PM style alternator, and the regulator is a shunt style
>regulator, and breaking that C-B connection removes the shunt load,
>then I can see how the regulator might be damaged. If the regulator
>sensing/control semiconductors are still connected to the alternator
>output but the shunt *isn't*, then the alternator could well be able
>to create a high enough voltage to exceed the max voltage ratings of
>the devices.
Nobody has built a shunt style regulator in
a very long time. A few small systems on motor
bikes and snowmobiles popularized the simple
design but the B&C regulators have never been
shunt . . . the alleged schematic of the Ducatti
R/R is also a series regulator.
They are manufactured as a spares item but better
regulators are so easy to design, there's no reason
to stay with shunt style.
>Having the shunt *in* the circuit would ensure that the voltage
>never got that high.
but it WOULD drive internal energy dissipation
to the max and, give the demonstrably poor
thermal management of many designs, could
toast the device. But I'm pretty sure
nobody builds/offers that control philosophy to
on the product we're using.
Bob . . .
Message 13
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Subject: | Re: Composite Aircraft and Lightning Strikes |
Before getting really wound up about lightning protection first understand
the risk and then figure the mitigation. Look at the accident statistics-
how many light aircraft have been struck by lightning and not survived? The
answer is very, very few - in the US and in Europe. For whatever reason.
Thunderstorms kill many people but lightning does not. My conclusion is
that airframe lightning protection is not worthwhile. Thunderstorm
protection is difficult so I avoid them.
Peter
On 1 Jul 2016 04:50, "William Hunter" <billhuntersemail@gmail.com> wrote:
> billhuntersemail@gmail.com>
>
> Hi All,
>
> There is a discussion brewing on the Velocity Owners Builders Association
> about composite aircraft and lightning strikes.
>
> What sparked (sorry) this discussion was a question about static wicks and
> if they could be useful on composite aircraft and now there is some good
> bantering going on about lightning strikes and composite
> aircraft...so...naturally I thought since there is some really sharp
> electrical folks on this forum I would ask you all for your feedback on the
> subject and I will certainly give you credit for your feedback and
> suggestions (of course I could not try to pass this knowledge off as being
> my own because that cat is already out of the bag and they would never
> believe it came from me).
>
> Anyhoo...here are some questions (if you think up others please feel free
> to
> add):
>
> -Would static wicks be beneficial to add to a composite aircraft?
>
> -If adding static wicks to a composite airplane, where should they be
> added?
>
> -Should control surfaces be bonded to the aircraft structure if static
> wicks
> are used (and even if static wicks are not used)?
>
> -Should all of the metal components of the aircraft be bonded together and
> if so what technique should be employed to do so?
>
> -Does anyone know of any lightning strike incidents to composite aircraft
> and if so what damage to the aircraft structure/components have occurred?
>
> -What causes lightning to be attracted to airplanes and/or why does
> lightning hit airplanes (yes, I can understand why lightning hits
> trees/buildings/other items that are connected to earth but an airplane is
> not connected to earth...if it had just taken off I could see the static in
> the wake leading to ground however an airplane in cruise flight is another
> story)?
>
> -Are composite aircraft more or less likely to be hit by lightning than
> metal airplanes?
>
> -Are there any techniques or design considerations that would mitigate the
> chance of lightning strikes on the composite aircraft and/or the damage
> being done should the aircraft be hit?
>
> -On production composite aircraft, what if any equipment/design
> considerations have been required by the FAA to be employed in reducing the
> chances of and/or in mitigating the effect of a lightning strike?
>
> -Some guys are discussing using Carbon Fiber or mesh being installed under
> the surfaces of the airplane to transfer the energy of a lightning strike
> so
> if a mesh of some sort is indeed used, will it help or hurt in reducing the
> chances of and/or in mitigating the effect of a lightning strike (if the
> mesh is not robust enough to conduct the extreme electrical current by a
> lightning strike could it make the problem worse (as a lightning rod on a
> house has a too small conductor then the lightning rod attracts the
> lightning and then once the lightning does actually hit the rod the
> conductor to ground melts and now the house structure becomes the conduit
> to
> ground)?
>
> Please dream up other thoughts in the area of lightning strikes and I will
> certainly forward them on.
>
> We appreciate your help in making the design of the Velocity aircraft more
> safe during this time of year!!!
>
> ..
>
> Cheers!!!
>
> Bill Hunter
>
>
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