Today's Message Index:
----------------------
1. 01:49 AM - Re: Fuel sw? (Steve Hunt)
2. 02:04 AM - Fuel Sw (Steve Hunt)
3. 07:47 AM - Re: Turbo pressure to mags? (Robert L. Nuckolls, III)
4. 08:02 AM - Re: Turbo pressure to mags? (Richard Tasker)
5. 08:31 AM - Re: Fuel sw? (Tore S. Bristol)
6. 08:39 AM - Re: Turbo pressure to mags? (Pete & Farrell Rouse)
7. 08:52 AM - Re: Resistive Fuel Sensors (Trampas)
8. 09:40 AM - Re: Turbo pressure to mags? (Matt Prather)
9. 09:56 AM - Re: Turbo pressure to mags? (Paul A. Franz, P.E.)
10. 10:58 AM - Re: Turbo pressure to mags? ()
11. 11:20 AM - Re: [Continues] Intermittent Internet Connectivity Issues to (Matt Dralle)
12. 12:00 PM - Re: Fuel Sw (Robert L. Nuckolls, III)
13. 01:26 PM - Re: Thermocouples (Gary Casey)
14. 01:26 PM - Re: Turbo pressure to mags? (Gary Casey)
15. 02:12 PM - Re: Re: Turbo pressure to mags? (George Braly)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Steve Hunt" <Stephen.Hunt19@btinternet.com>
Hi Bob,
the background to EFIS in my "8" is as follows.
I would never choose to fly IFR or at night with one engine driving the one prop
, its not wrong to do this elsewhere,however, I simply dont think it is a good
thing for me to do.(despite my 13000 hrs flying...or maybe because of it?!)...
My EFIS Lite weighs 520 grammes...about 3.25 Lbs. For this I get all the basic
flight insts plus a GPS driven moving map plus a nav system (virt VOR with 360
"compass".) Its a heck of a lot of kit for 500 grammes!
We dont have much free airspace on our little Island and we need to be able to
either find our way around with great accuracy or accept help with radar headings
in order to avoid all the controlled airspace when in our home builds.
Yes I like aeros but I also want to tour with my `plane.
The set up proposed would be very unwise given the above and our weather when visual
can mean "in sight of the ground" but with perhaps no discernable horizon.
So this was my logic to having stnd by power available , for at least ten minutes
battery operation. This would give me time to get back on the ground in most
circumstances that I can imagine when flying over land in UK.
The ammeter question is well off my patch hence the dumb question. However, what
I was referring was the advice on pages 7-12 and 7-13 of "The Aeroelectric Connection".
I wondered if I wired it to the B lead just before my starter relay
....would that be a reasonable thing to do? Is there a better solution? Have
I completely miss understood again!
rgds
Steve
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Steve Hunt" <Stephen.Hunt19@btinternet.com>
Whoops,
just re read my latest dumb question.What I meant to say was....would you recommend
I fit a battery ammeter as described on page 7-14, or is there a better solution(less
weighty)....or indeed is this me being old fashioned and I simply
dont need one?
I will try to make the Kansas seminar!!!
Steve
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Turbo pressure to mags? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 02:50 AM 12/24/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Ronald J. Parigoris"
><rparigor@suffolk.lib.ny.us>
>
>I know that when flying high, that Turbo pressure is sent to mags.
>
>In WW2 They sent pressure to ignition harnesses as well.
>
>I am not sure why this suppresses arcing????
>
>I think a vacuum is a better insulator than air???
Not at all. Your spark plugs used to be tested by
observing the spark gap through a windowed chamber
while air pressure was adjusted until the spark would
just stop. The better plugs will spark at 150 psi, poorer
ones at lesser pressures. Vacuum tubes won't function
with even a small amount of air present.
>Is it perhaps that it is not just pressurized, but is allowing an airflow
>to cool
>things down?
Turbo C210's and Mooney's have a small pipe that takes pressurized
air downstream of turbochargers to the magneto housings.
Without such pressurization, they're in danger of internal
arc-over. Waveguides in the B-52 radar system are pressurized,
without pressurization, the 50 kilowatt pulse of energy
going out to the antenna would never make it . . . one
would have a little storm of mini-lightning strikes going
on somewhere in the feedline.
Bob . . .
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Turbo pressure to mags? |
--> AeroElectric-List message posted by: Richard Tasker <retasker@optonline.net>
Air at atmospheric pressure is more resistant to arcing than lower
pressure air. If you had a true vacuum then the arcing would be even
more suppressed, but at high altitudes you only have lower pressure -
not vacuum. As you mentioned, higher pressure air cools better.
My $0.02...
Dick Tasker
Ronald J. Parigoris wrote:
>--> AeroElectric-List message posted by: "Ronald J. Parigoris" <rparigor@suffolk.lib.ny.us>
>
>I know that when flying high, that Turbo pressure is sent to mags.
>
>In WW2 They sent pressure to ignition harnesses as well.
>
>I am not sure why this suppresses arcing????
>
>I think a vacuum is a better insulator than air???
>
>Is it perhaps that it is not just pressurized, but is allowing an airflow to cool
>things down?
>
>Thx.
>Ron Parigoris
>
>
>
>
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Tore S. Bristol" <tf51@c2i.net>
----- Original Message -----
From: "Steve Hunt" <Stephen.Hunt19@btinternet.com>
Subject: Re: AeroElectric-List: Fuel sw?
> --> AeroElectric-List message posted by: "Steve Hunt"
<Stephen.Hunt19@btinternet.com>
>
> Hi Bob,
>
> the background to EFIS in my "8" is as follows.
>
> I would never choose to fly IFR or at night with one engine driving the
one prop , its not wrong to do this elsewhere,however, I simply dont think
it is a good thing for me to do.(despite my 13000 hrs flying...or maybe
because of it?!)...
>
> My EFIS Lite weighs 520 grammes...about 3.25 Lbs. For this I get all the
basic flight insts plus a GPS driven moving map plus a nav system (virt VOR
with 360 "compass".) Its a heck of a lot of kit for 500 grammes!
>
> We dont have much free airspace on our little Island and we need to be
able to either find our way around with great accuracy or accept help with
radar headings in order to avoid all the controlled airspace when in our
home builds.
>
> Yes I like aeros but I also want to tour with my `plane.
>
> The set up proposed would be very unwise given the above and our weather
when visual can mean "in sight of the ground" but with perhaps no
discernable horizon.
>
> So this was my logic to having stnd by power available , for at least ten
minutes battery operation. This would give me time to get back on the
ground in most circumstances that I can imagine when flying over land in UK.
>
>
> The ammeter question is well off my patch hence the dumb question.
However, what I was referring was the advice on pages 7-12 and 7-13 of "The
Aeroelectric Connection". I wondered if I wired it to the B lead just before
my starter relay ....would that be a reasonable thing to do? Is there a
better solution? Have I completely miss understood again!
>
> rgds
>
> Steve
>
> Hi!
Good news; 520 g is more like 1,15 lbs so you just saved another 2,1
lbs!
Regards
Tore S Bristol
Norway
>
>
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Turbo pressure to mags? |
--> AeroElectric-List message posted by: "Pete & Farrell Rouse" <pete-farrell@kc.rr.com>
Ron,
There is something called 'breakdown voltage' that is basically the voltage
necessary to ionize the air sufficiently between a gap of a know distance to
induce an arc across the gap. The breakdown voltage gets lower as the air
density gets lower, thus the breakdown voltage decreases with increasing
altitude. There is something called the 'Paschen Curve' that describes this
phenomenon. The higher the voltage, the more probability of arcing at
altitude.
The only reason I am able to comment on this at all, is that I asked a very
similar question in the last few days.
Well, I just ran out of knowledge, so I'll shut up now.....
Happy Holidays,
Pete Rouse
----- Original Message -----
From: "Ronald J. Parigoris" <rparigor@SUFFOLK.LIB.NY.US>
Subject: AeroElectric-List: Turbo pressure to mags?
> --> AeroElectric-List message posted by: "Ronald J. Parigoris"
<rparigor@suffolk.lib.ny.us>
>
> I know that when flying high, that Turbo pressure is sent to mags.
>
> In WW2 They sent pressure to ignition harnesses as well.
>
> I am not sure why this suppresses arcing????
>
> I think a vacuum is a better insulator than air???
>
> Is it perhaps that it is not just pressurized, but is allowing an airflow
to cool
> things down?
>
> Thx.
> Ron Parigoris
>
>
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Resistive Fuel Sensors |
--> AeroElectric-List message posted by: "Trampas" <tstern@nc.rr.com>
Some sensors you can put in parallel with multiple gauges.
Most sensors which have three wires, like most resistive float senders
outputs a voltage on one of the pins which varies. Multiple gauges can be
placed in parallel with theses sensors, assuming the gauges have a relative
high impedance input. Now with that said you would have to check with EIS to
determine if their unit can be put in parallel with an analog gauge.
As far as oil pressure if you use a switch it is easy to have multiple
devices triggered off the same switch.
One of the big things in my mind about using multiple gauges is for the
redundancy, however if you are using the same sensor then your redundancy is
really not there, since from my experience the sensor is more likely to fail
than a gauge.
Personally I see a need for a back up oil pressure gauge and a back up
voltage gauge, especially with electronic instruments. Let's not forget that
your job is to fly the plane, with or with out engine running.
As far as knowing how much fuel you have which most people have a reasonable
guess based on experience, after all if you are unsure of your fuel level,
then you need fuel.
Regards,
Trampas
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of John
Slade
Subject: RE: AeroElectric-List: Resistive Fuel Sensors
--> AeroElectric-List message posted by: "John Slade"
<sladerj@bellsouth.net>
> Are there any concerns about having more than one gauge attached
> to these sensors?
Now that's a question I'd like to hear the answer to. My system needs 3 oil
pressure sensors (hobbs, gauge and voice annunciator). Can I use the same
sensor for all of them? Same's true of oil temp & coolant temp.
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Turbo pressure to mags? |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
Here is a chart that lists the dielectric strengths of
various common materials. Note that vacuum is one of
the lowest (worst) dielectric strengths.
Regards,
Matt-
N34RD
Dielectric strengths for insulators
Dielectric strength in kilovolts per inch (kV/in):
Material* Dielectric strength
=========================================
Vacuum --------------------- 20
Air ------------------------ 20 to 75
Porcelain ------------------ 40 to 200
Paraffin Wax --------------- 200 to 300
Transformer Oil ------------ 400
Bakelite ------------------- 300 to 550
Rubber --------------------- 450 to 700
Shellac -------------------- 900
Paper ---------------------- 1250
Teflon --------------------- 1500
Glass ---------------------- 2000 to 3000
Mica ----------------------- 5000
> --> AeroElectric-List message posted by: "Ronald J. Parigoris"
> <rparigor@suffolk.lib.ny.us>
>
> I know that when flying high, that Turbo pressure is sent to mags.
>
> In WW2 They sent pressure to ignition harnesses as well.
>
> I am not sure why this suppresses arcing????
>
> I think a vacuum is a better insulator than air???
>
> Is it perhaps that it is not just pressurized, but is allowing an
> airflow to cool things down?
>
> Thx.
> Ron Parigoris
>
>
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Turbo pressure to mags? |
--> AeroElectric-List message posted by: "Paul A. Franz, P.E." <paul@eucleides.com>
On Wed, 2003-12-24 at 07:59, Richard Tasker wrote:
> --> AeroElectric-List message posted by: Richard Tasker <retasker@optonline.net>
>
> Air at atmospheric pressure is more resistant to arcing than lower
> pressure air. If you had a true vacuum then the arcing would be even
> more suppressed, but at high altitudes you only have lower pressure -
> not vacuum. As you mentioned, higher pressure air cools better.
Voltage required to arc is actually a U shaped curve with the minimum
arcing voltage to hop a 1 cm gap occurring at about 150,000 FT DA.
Rather than depend on air as an insulator in high flying stuff Reynolds
makes elastomer seals that aren't susceptible to this arc length creep.
<http://www.reynoldsindustries.com/product/2multipin/page17.asp>
The above link shows Paschen's 19th century results when this was
studied.
--
PAF Consulting Engineers | 427 - 140th Ave NE
(425)641-8202 voice | Bellevue, WA 98005
(425)641-1773 fax | <mailto:paul@eucleides.com>
GnuPG Public Key - <http://eucleides.com/pgpkey.asc>
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Turbo pressure to mags? |
--> AeroElectric-List message posted by: <chaskuss@bellsouth.net>
Ron
You have it backwards. Air is a relatively poor conductor. It acts as an insulator.
Since the air at high altitudes is less dense, it is not as good at insulating
spark arcing. Pressurizing the interior of the magnetoes and the wiring
harnesses helps suppress arcing by supplying a more dense atmosphere.
Charlie Kuss
>
> From: "Ronald J. Parigoris" <rparigor@SUFFOLK.LIB.NY.US>
> Date: 2003/12/24 Wed AM 02:50:06 EST
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: Turbo pressure to mags?
>
>
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: [Continues] Intermittent Internet Connectivity |
Issues to
Matronics...
--> AeroElectric-List message posted by: Matt Dralle <dralle@matronics.com>
Dear Listers,
Pacbell is suppose to be working the Matronics connectivity issue this
morning. Intermittent connectivity is still a issue although things are
better than yesterday. They will probably be doing some intrusive testing
on the line later today which will disrupt connections during the test.
More information as it becomes available!
Thanks for your patience.
Matt Dralle
Matronics Email List Admin.
At 02:59 PM 12/23/2003 Tuesday, you wrote:
>Dear Listers,
>
>Starting at about 1:05pm PDT Matronics starting having intermittent
>connectivity issues to the Internet. I've called the ISP and they are
>looking into the problem and may do intrusive testing on the line at some
>point this afternoon/evening. For the most part, things seem to be
>working right now, but the line will drop out every once in a while for 2
>to 3 minutes.
>
>This problem will effect connections to the Matronics Web server as well
>as distribution of List mail.
>
>I will post a follow up when the problem has been resolved... Hopefully
>later today.
>
>Matt Dralle
>Matronics Email List Admin.
>
>do not archive
Matt G Dralle | Matronics | PO Box 347 | Livermore | CA | 94551
925-606-1001 V | 925-606-6281 F | dralle@matronics.com Email
http://www.matronics.com/ WWW | Featuring Products For Aircraft
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 10:04 AM 12/24/2003 +0000, you wrote:
>--> AeroElectric-List message posted by: "Steve Hunt"
><Stephen.Hunt19@btinternet.com>
>
>Whoops,
>just re read my latest dumb question.What I meant to say was....would you
>recommend I fit a battery ammeter as described on page 7-14, or is there a
>better solution(less weighty)....or indeed is this me being old fashioned
>and I simply dont need one?
>
>I will try to make the Kansas seminar!!!
Battery ammeters have some degree of utility for troubleshooting
as do alternator loadmeters. The later are easier to install
while maintaining a minimize the fat-wires-in-the-cockpit
philosophy. I'd recommend a loadmeter if you have any ammeter
at all. A low voltage warning light may well suffice for all
necessary in-flight electrical system instrumentation.
Bob . . .
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | RE: Thermocouples |
--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<If you need a multi-way switch, use the same kind of wire to the switch,
>then it is conservative to use the same kind of wire from the switch to the
>instrument. Caveat: the switch needs to be in the same temperature zone as
>the instrument since the 'cold junction' matches are critical to
>sensor/instrument accuracy. Anytime one has a connection in the sensor
>wire, one creates another cold junction.
It's more accurate to say that deleterious effects of
any parasitic thermocouples generated when introducing
foreign metals can be minimized as long as whatever is done
to one side of the thermocouple path is done to the other side
but in opposite polarity . . . it's a sorta two-wrongs-can-
make-a-right approach.>>
Bob is certainly correct here. A long time ago when we were using passive
"pyrometers," really just voltmeters, to read thermocouples we even went as
far as to use a special selector switch that was made of the right
materials. But then I worked at a powerplant one summer and there were
thermocouples half a mile away from the instrument. We ran the TC wires to
a junction box, connected them to copper and ran the rest of the way in
copper. For an aircraft it would work just fine that way. Splice the TC
wires under the cowl to copper wires, run the copper wires to an ordinary
wafer switch if you like, and then to the instrument. Just make sure you
don't make a spice on one side of the circuit at a location that is at a
different temperature than the splice on the other side of the circuit. It
all works very easily and if there is an error it is so small that you'll
never find it.
Gary Casey
Message 14
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | RE: Turbo pressure to mags? |
--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<--> AeroElectric-List message posted by: "Ronald J. Parigoris"
<rparigor@suffolk.lib.ny.us>
I know that when flying high, that Turbo pressure is sent to mags.
In WW2 They sent pressure to ignition harnesses as well.
I am not sure why this suppresses arcing????
I think a vacuum is a better insulator than air???
Is it perhaps that it is not just pressurized, but is allowing an airflow to
cool
things down?
Thx.
Ron Parigoris>>
Vacuum might be a better INSULATOR, but the higher the pressure of the air
the higher its DIELECTRIC STRENGTH. In other words it will take a higher
voltage to arc when the pressure is higher. And this is why the magnetos
are sometimes pressurized. The problem mostly exists at the rotor where at
some voltage the current will arc to another post rather than to a plug. A
Naturally Aspirated engine doesn't have this problem because the pressure in
the cylinder also goes down with higher altitude. A supercharged engine is
typically operated at a constant manifold pressure and hence a constant
cylinder pressure regardless of altitude. If the magneto is pressurized the
potential for cross-firing is minimized.
Gary Casey
Message 15
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | RE: Turbo pressure to mags? |
--> AeroElectric-List message posted by: George Braly <gwbraly@gami.com>
Re mags:
If you use Bendix 1200 mags, they do NOT need to be pressurized
until above about 28000 feet.
If you use Slick mags, they need to be pressurized above about
12,000'.
Very simple. Very predictable. Very repeatable.
I have flown an unpressurized set of Bendix 1200 series mags to
33,000'D.A. before they started to arc.
Regards, George
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Gary
Casey
Subject: AeroElectric-List: RE: Turbo pressure to mags?
--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<--> AeroElectric-List message posted by: "Ronald J. Parigoris"
<rparigor@suffolk.lib.ny.us>
I know that when flying high, that Turbo pressure is sent to mags.
In WW2 They sent pressure to ignition harnesses as well.
I am not sure why this suppresses arcing????
I think a vacuum is a better insulator than air???
Is it perhaps that it is not just pressurized, but is allowing an airflow to
cool
things down?
Thx.
Ron Parigoris>>
Vacuum might be a better INSULATOR, but the higher the pressure of the air
the higher its DIELECTRIC STRENGTH. In other words it will take a higher
voltage to arc when the pressure is higher. And this is why the magnetos
are sometimes pressurized. The problem mostly exists at the rotor where at
some voltage the current will arc to another post rather than to a plug. A
Naturally Aspirated engine doesn't have this problem because the pressure in
the cylinder also goes down with higher altitude. A supercharged engine is
typically operated at a constant manifold pressure and hence a constant
cylinder pressure regardless of altitude. If the magneto is pressurized the
potential for cross-firing is minimized.
Gary Casey
---
Incoming mail is certified Virus Free.
---
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|