Today's Message Index:
----------------------
1. 01:42 AM - Re: ELT antenna placement (Jared Yates)
2. 02:49 AM - Re: It's nice when the center holds . . . (Peter Pengilly)
3. 04:10 AM - ELT antenna placement ()
4. 05:13 AM - Re: ELT antenna placement (Dave Saylor)
5. 07:21 AM - Re: It's nice when the center holds . . . (Larry Mac Donald)
6. 07:30 AM - Re: ELT antenna placement (Kelly McMullen)
7. 07:39 AM - Re: It's nice when the center holds . . . (Robert L. Nuckolls, III)
8. 07:54 AM - Re: ELT antenna placement (Robert L. Nuckolls, III)
9. 08:19 AM - Re: ELT antenna placement (Robert L. Nuckolls, III)
10. 08:49 AM - ELT antenna placement (BobsV35B@aol.com)
11. 11:13 AM - Re: Re: Viking Engine (Ed Gilroy)
12. 03:02 PM - Re: It's nice when the center holds . . . (Peter Pengilly)
13. 04:00 PM - Re: It's nice when the center holds . . . (Dave Saylor)
14. 04:13 PM - Re: It's nice when the center holds . . . (Neal George)
15. 05:06 PM - Re: ELT antenna placement (Kelly McMullen)
16. 06:51 PM - Re: ELT antenna placement (Paul Kuntz)
17. 07:44 PM - Electrical System Drawing (Paul Zimmer)
18. 07:50 PM - Electrical System Drawing (Paul Zimmer)
Message 1
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Subject: | Re: ELT antenna placement |
In one prior case, we had an airplane that was transmitting ground control v
oice (121.9) over 121.5. We attributed it to resonance on the elt antenna, w
hich was in a non standard location for that type, closer than normal to the
vhf com. After moving the elt antenna back a couple of feet the bleed over
stopped. This type of problem might be something to consider in your decis
ion.
On Jul 16, 2011, at 1:28, Paul Kuntz <paul.r.kuntz@gmail.com> wrote:
> I'm installing a 121.5/406 MHz ELT in my homebuilt project. The installat
ion instructions tell me to put the ELT whip antenna at least 3 feet from my
VHF radio antenna. Is this really necessary? There is the possibility of m
anually activating the ELT in the air in the event of an emergency, while co
ntinuing to communicate with the VHF radio, but I'm thinking that the more l
ikely scenarios will be to operate one or the other, but not both. That is,
the ELT becomes a factor only in the case of a true emergency, in which cas
e I would first squawk emergency and communicate the situation by VHF voice (
flying the airplane first, of course). Then, activate the ELT (one button p
ress) if a forced landing appears inevitable, but I'm probably done talking o
n the radio at that point.
>
> Is the concern simply the presence of another vertically oriented conducto
r in relatively close proximity to the antenna in use, thus influencing its p
erformance? Even if both the ELT and the VHF radio are active at the same t
ime, is 3 ft of separation important?
>
> At any rate, it would be more convenient from an installation perspective t
o put them closer together. Any advice?
>
> Thanks,
> Paul Kuntz
>
>
==========================
=========
==========================
=========
==========================
=========
==========================
=========
>
Message 2
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Subject: | Re: It's nice when the center holds . . . |
Bob,
I don't know F-16 systems, but have experience of other single seat
military aircraft. I'm guessing the Hydrazine unit is a light weight
method of mitigating the hazard of providing power once the (single)
motor has stopped, without fitting a huge battery. Most combat aircraft
are started with a ground power unit, so the battery doesn't have to be
very big. I'm guessing the electrical demands of an F-16 are quite large
(fly-by-wire), even with load shedding, so a huge battery would be
required to get the airplane to the ground from max altitude - or a
reasonably powerful (heavy) gas turbine APU. So a one shot hydrazine
based system is a reasonable (light weight) solution, although it has a
maintenance overhead. Bear in mind the F-16 was designed as a
lightweight fighter, so weight saving was probably quite high on the
priority list.
Peter
On 15/07/2011 22:47, Robert L. Nuckolls, III wrote:
>>
>>
>> What is really dead is the power source!
>>
>
> The last few words of the pilot suggested something I'd
> not heard before. He talked about a 'hydrazine' hazard
> around his aircraft as he was talking with locals at
> his airport of destination. There was also a reference
> to an "EPU" . . . 'possible emergency power unit'.
>
> Hydrazine and sulfuric acid combine in a manner that
> provides spontaneous combustion with a very energetic
> release of energy. In this case, I'm thinking that the
> airplane was fitted with what could be a compact
> and relatively light weight energy source that required
> very little maintenance and has a long storage life.
> (I've seen AQM-37 hydrazine powered targets successfully
> flown after 20 years in storage).
>
> It would be interesting to hear from folks with experience
> inside the operating world of this style of aircraft
> as to it's 'dead stick' options for power.
>
> Bob . . .
>
> *
>
>
> *
Message 3
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Subject: | ELT antenna placement |
7/16/2011
Hello Paul, You wrote: "Is this really necessary?"
After 6 years plus of construction and many hours of preparation for the
first flight in my KIS TR-1 experimental amateur built aircraft I was unable
to taxi out of the apron area because every time I keyed my number one VHF
com radio to request taxi clearance from ground control the ELT transmitter
was activated -- very frustrating.
The problem was caused by proximity and orientation of the antennas of the
two devices. I eventually relocated the ELT antenna -- problem solved.
OC
PS for Bruce: Knowledge of 14 CFR 91.207 (f) (4) permitted me to disable the
ELT and complete the first flight as plannned.
================================================================
Time: 10:33:48 PM PST US
Subject: AeroElectric-List: ELT antenna placement
From: Paul Kuntz <paul.r.kuntz@gmail.com>
I'm installing a 121.5/406 MHz ELT in my homebuilt project. The
installation instructions tell me to put the ELT whip antenna at least 3
feet from my VHF radio antenna. Is this really necessary? There is the
possibility of manually activating the ELT in the air in the event of an
emergency, while continuing to communicate with the VHF radio, but I'm
thinking that the more likely scenarios will be to operate one or the other,
but not both. That is, the ELT becomes a factor only in the case of a true
emergency, in which case I would first squawk emergency and communicate the
situation by VHF voice (flying the airplane first, of course). Then,
activate the ELT (one button press) if a forced landing appears inevitable,
but I'm probably done talking on the radio at that point.
Is the concern simply the presence of another vertically oriented conductor
in relatively close proximity to the antenna in use, thus influencing its
performance? Even if both the ELT and the VHF radio are active at the same
time, is 3 ft of separation important?
At any rate, it would be more convenient from an installation perspective to
put them closer together. Any advice?
Thanks,
Paul Kuntz
Message 4
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Subject: | Re: ELT antenna placement |
I agree, I've seen comm radios set of a nearby ELT on several
occasions. It's not uncommon at all.
I'd keep those antennas away from each other.
Dave Saylor
AirCrafters
140 Aviation Way
Watsonville, CA 95076
831-722-9141 Shop
831-750-0284 Cell
On Sat, Jul 16, 2011 at 4:06 AM, <bakerocb@cox.net> wrote:
>
> 7/16/2011
>
> Hello Paul, You wrote: "Is this really necessary?"
>
> After 6 years plus of construction and many hours of preparation for the
> first flight in my KIS TR-1 experimental amateur built aircraft I was unable
> to taxi out of the apron area because every time I keyed my number one VHF
> com radio to request taxi clearance from ground control the ELT transmitter
> was activated -- very frustrating.
>
> The problem was caused by proximity and orientation of the antennas of the
> two devices. I eventually relocated the ELT antenna -- problem solved.
>
> OC
>
> PS for Bruce: Knowledge of 14 CFR 91.207 (f) (4) permitted me to disable the
> ELT and complete the first flight as plannned.
>
> ================================================================
>
> Time: 10:33:48 PM PST US
> Subject: AeroElectric-List: ELT antenna placement
> From: Paul Kuntz <paul.r.kuntz@gmail.com>
>
> I'm installing a 121.5/406 MHz ELT in my homebuilt project. The
> installation instructions tell me to put the ELT whip antenna at least 3
> feet from my VHF radio antenna. Is this really necessary? There is the
> possibility of manually activating the ELT in the air in the event of an
> emergency, while continuing to communicate with the VHF radio, but I'm
> thinking that the more likely scenarios will be to operate one or the other,
> but not both. That is, the ELT becomes a factor only in the case of a true
> emergency, in which case I would first squawk emergency and communicate the
> situation by VHF voice (flying the airplane first, of course). Then,
> activate the ELT (one button press) if a forced landing appears inevitable,
> but I'm probably done talking on the radio at that point.
>
> Is the concern simply the presence of another vertically oriented conductor
> in relatively close proximity to the antenna in use, thus influencing its
> performance? Even if both the ELT and the VHF radio are active at the same
> time, is 3 ft of separation important?
>
> At any rate, it would be more convenient from an installation perspective to
> put them closer together. Any advice?
>
> Thanks,
> Paul Kuntz
>
>
Message 5
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Subject: | Re: It's nice when the center holds . . . |
Carlos,
I'll take a shot at that. Back in the days of yore airplanes were slower
and if you lost your engine your control surfaces, on some airplanes, w
ere sluggish at best. This made the stick somewhat unresponsive. So some
one said "it's a dead stick" Just one of those things that stuck in our
lexicon. Another such example was told to us, my Aeronautics ground scho
ol, by our instructor. He had worked for the first air mail service. He,
and the rest of his team hosted a british aviator and as they were doin
g they're flying and lying the britisher mentioned the word altimeter. W
ell, up to that point we called the instrument an al-ta-meter. The briti
sh gentleman called it an al-tim-meter. The boys of the first air mail s
ervice thought that his way of saying it was more like the way it should
be said. And it stuck, world wide. Things just happen that way.
Larry
On Jul 15, 2011, at 2:55 PM, Carlos Trigo wrote:
> Nice landing, and a very good demonstration of excellent pilot skills!
>
> The only thing I don=92t really understand is why you (native English
speakers) call this situation a =93Dead Stick=94 landing, when this is e
verything but a dead stick. On the contrary, this is a very =93Alive sti
ck=94 situation=85.
> What is really dead is the power source!
>
> Carlos Trigo
>
>
> > -----Original Message-----
> > From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aer
oelectric-list-
> > server@matronics.com] On Behalf Of Robert L. Nuckolls, III
> > Sent: sexta-feira, 15 de Julho de 2011 18:40
> > To: aeroelectric-list@matronics.com
> > Subject: AeroElectric-List: It's nice when the center holds . . .
> >
> > <nuckolls.bob@aeroelectric.com>
> >
> > See:
> >
> > http://www.patricksaviation.com/videos/SUPERGT/3384/
> >
> >
> > Bob . . .
> > ////
> > (o o)
>
>
========================
============
========================
============
========================
============
========================
============
>
____________________________________________________________
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Message 6
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Subject: | Re: ELT antenna placement |
Another risk is that many ELT transmitters are poorly shielded from
strong adjacent RF. Flying near a TV or FM transmitter antenna can cause
the oscillator of the ELT transmitter to radiate harmonics, which then
are picked up by your com radio, breaking squelch and causing poor
reception. My plane used to suffer from this syndrome until I moved one
of the VHF antennas to the belly.
On 7/16/2011 5:10 AM, Dave Saylor wrote:
> --> AeroElectric-List message posted by: Dave Saylor<dave.saylor.aircrafters@gmail.com>
>
> I agree, I've seen comm radios set of a nearby ELT on several
> occasions. It's not uncommon at all.
>
> I'd keep those antennas away from each other.
>
> Dave Saylor
> AirCrafters
> 140 Aviation Way
> Watsonville, CA 95076
> 831-722-9141 Shop
> 831-750-0284 Cell
>
>
> On Sat, Jul 16, 2011 at 4:06 AM,<bakerocb@cox.net> wrote:
>> --> AeroElectric-List message posted by:<bakerocb@cox.net>
>>
>> 7/16/2011
>>
>> Hello Paul, You wrote: "Is this really necessary?"
>>
>> After 6 years plus of construction and many hours of preparation for the
>> first flight in my KIS TR-1 experimental amateur built aircraft I was unable
>> to taxi out of the apron area because every time I keyed my number one VHF
>> com radio to request taxi clearance from ground control the ELT transmitter
>> was activated -- very frustrating.
>>
>> The problem was caused by proximity and orientation of the antennas of the
>> two devices. I eventually relocated the ELT antenna -- problem solved.
>>
>> OC
>>
>> PS for Bruce: Knowledge of 14 CFR 91.207 (f) (4) permitted me to disable the
>> ELT and complete the first flight as plannned.
>>
>> ================================================================
>>
>> Time: 10:33:48 PM PST US
>> Subject: AeroElectric-List: ELT antenna placement
>> From: Paul Kuntz<paul.r.kuntz@gmail.com>
>>
>> I'm installing a 121.5/406 MHz ELT in my homebuilt project. The
>> installation instructions tell me to put the ELT whip antenna at least 3
>> feet from my VHF radio antenna. Is this really necessary? There is the
>> possibility of manually activating the ELT in the air in the event of an
>> emergency, while continuing to communicate with the VHF radio, but I'm
>> thinking that the more likely scenarios will be to operate one or the other,
>> but not both. That is, the ELT becomes a factor only in the case of a true
>> emergency, in which case I would first squawk emergency and communicate the
>> situation by VHF voice (flying the airplane first, of course). Then,
>> activate the ELT (one button press) if a forced landing appears inevitable,
>> but I'm probably done talking on the radio at that point.
>>
>> Is the concern simply the presence of another vertically oriented conductor
>> in relatively close proximity to the antenna in use, thus influencing its
>> performance? Even if both the ELT and the VHF radio are active at the same
>> time, is 3 ft of separation important?
>>
>> At any rate, it would be more convenient from an installation perspective to
>> put them closer together. Any advice?
>>
>> Thanks,
>> Paul Kuntz
>>
>>
>>
>>
>>
>>
>>
>
>
Message 7
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Subject: | Re: It's nice when the center holds . . . |
At 04:46 AM 7/16/2011, you wrote:
>Bob,
>
>I don't know F-16 systems, but have experience of other single seat
>military aircraft. I'm guessing the Hydrazine unit is a light weight
>method of mitigating the hazard of providing power once the (single)
>motor has stopped, without fitting a huge battery. Most combat
>aircraft are started with a ground power unit, so the battery
>doesn't have to be very big. I'm guessing the electrical demands of
>an F-16 are quite large (fly-by-wire), even with load shedding, so a
>huge battery would be required to get the airplane to the ground
>from max altitude - or a reasonably powerful (heavy) gas turbine
>APU. So a one shot hydrazine based system is a reasonable (light
>weight) solution, although it has a maintenance overhead. Bear in
>mind the F-16 was designed as a lightweight fighter, so weight
>saving was probably quite high on the priority list.
That's about what I would have guessed.
Some years ago, there was some work described in
the development of tiny, combustion driven turbines
for hi-energy stand-by sources. One author even
hypothesized a lap-top computer running on butane.
Haven't heard/read anything along those lines since.
The GAR series IR guided missiles I used to work on
at Hughes-Tucson had a little bottle of nitrogen
held in liquid state at room temperatures . . . man,
that was a lot of pressure! A frangible diaphragm held
the liquid in check until launch. Then for the 90-second
or so service life of the missile, the liquid expanded
to run a small PM alternator that produced 150 watts
to power electronics. It was then routed to the back of
the IR optics to keep the lens cool at Lots-a-Mach. After
that, it pressurized an open loop hydraulic system that
operated flight controls at the trailing edges of the
guidance fins before being exhausted overboard. That
was in 1960.
Given the advances in really tiny gas turbines, it
seems certainly possible and perhaps practical to
craft a light weight power generation device with
considerable output and endurance while using up
much less volume and weight budget needed for batteries
of the same capability.
Some ideas take a very long time to evolve into
useful product . . .
Bob . . .
Message 8
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Subject: | Re: ELT antenna placement |
At 07:10 AM 7/16/2011, you wrote:
Saylor <dave.saylor.aircrafters@gmail.com>
I agree, I've seen comm radios set of a nearby ELT on several
occasions. It's not uncommon at all.
I'd keep those antennas away from each other.
It would appear to be the only option. It
may be very $difficult$ to fix what appears
to be a design bug internal to the ELT.
The earliest ELT's used a spring-loaded
mass to close an activation switch in response
to g-forces of a crash. No doubt modern ELTs
use the solid-state acceleration sensors
for this task . . . which produce VERY tiny
signals requiring a lot of circuit gain.
This type of circuitry offers a high risk
of vulnerability to RF interference. This
may be an area where qualification of the
device to standard DO-160 (good for part
23) stresses was insufficient to stand off
the extra-ordinary vulnerabilities of these
kinds of circuits. A lot of hardware we
did for the military and for Part-25 and up
applications was exposed to really nasty
RF radiation . . . 200 volts/meter or more
. . . during qualification. No doubt this
extra step in qualification would have exposed
vulnerabilities that are now plaguing customers.
> Paul wrote:
> I'm installing a 121.5/406 MHz ELT in my homebuilt project. The
> installation instructions tell me to put the ELT whip antenna at least 3
> feet from my VHF radio antenna. Is this really necessary? There is the
> possibility of manually activating the ELT in the air in the event of an
> emergency, while continuing to communicate with the VHF radio, but I'm
> thinking that the more likely scenarios will be to operate one or the other,
> but not both. That is, the ELT becomes a factor only in the case of a true
> emergency, in which case I would first squawk emergency and communicate the
> situation by VHF voice (flying the airplane first, of course). Then,
> activate the ELT (one button press) if a forced landing appears inevitable,
> but I'm probably done talking on the radio at that point.
>
> Is the concern simply the presence of another vertically oriented conductor
> in relatively close proximity to the antenna in use, thus influencing its
> performance? Even if both the ELT and the VHF radio are active at the same
> time, is 3 ft of separation important?
>
> At any rate, it would be more convenient from an installation perspective to
> put them closer together. Any advice?
Give it a try . . . but with a Plan-B for moving
one or both of the antennas to achieve demonstrably
necessary separation. I suspect that not all ELT
products are victim to the hypothesized vulnerability
I cited above. There are no grave performance issues
that would arise from antenna proximity issues so if
you "get away Scott free" with your desired configuration,
you're good to go.
Bob . . .
Message 9
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Subject: | Re: ELT antenna placement |
At 09:27 AM 7/16/2011, you wrote:
>
>Another risk is that many ELT transmitters are poorly shielded from
>strong adjacent RF. Flying near a TV or FM transmitter antenna can
>cause the oscillator of the ELT transmitter to radiate harmonics,
>which then are picked up by your com radio, breaking squelch and
>causing poor reception. My plane used to suffer from this syndrome
>until I moved one of the VHF antennas to the belly.
Interesting! I hadn't thought of that scenario. Unlike
transceivers where the antenna is connected to a receiver
input circuit 99.9% of the time, the ELT antenna is
permanently connected to the output circuitry of a
transmitter's power output stage.
A strong analog TV station impressed on the ELT
antenna could be conducted into the non-linear,
transistor junctions where the TV signal could
produce inter-modulation products that spread over
a very wide spectrum. Now that we're all-digital
in the off-air TV world, I suspect probability
is reduced. I'm aware of no other "trash rich"
high power signals that would produce this
effect today.
This is a phenomenon that was never explored
by DO-160 although I've read some military
qualification test protocols that do look for
inter-modulation mixing and re-radiation of
foreign energies coming down the antenna feedline.
Bob . . .
Message 10
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Subject: | ELT antenna placement |
Good Morning Paul and Jared,
Way out of my area of expertise, but it is my understanding that having
another vertical metal element close to the transmitting or receiving antenna
makes the combination very directional. Rarely a problem when close to the
station but could reduce the range capability at some angles from the
aircraft.
Happy Skies,
Old Bob
Do Not Archive
In a message dated 7/16/2011 3:42:58 A.M. Central Daylight Time,
email@jaredyates.com writes:
In one prior case, we had an airplane that was transmitting ground control
voice (121.9) over 121.5. We attributed it to resonance on the elt
antenna, which was in a non standard location for that type, closer than normal
to
the vhf com. After moving the elt antenna back a couple of feet the bleed
over stopped. This type of problem might be something to consider in your
decision.
On Jul 16, 2011, at 1:28, Paul Kuntz <_paul.r.kuntz@gmail.com_
(mailto:paul.r.kuntz@gmail.com) > wrote:
I'm installing a 121.5/406 MHz ELT in my homebuilt project. The
installation instructions tell me to put the ELT whip antenna at least 3 feet
from
my VHF radio antenna. Is this really necessary? There is the possibility
of manually activating the ELT in the air in the event of an emergency,
while continuing to communicate with the VHF radio, but I'm thinking that the
more likely scenarios will be to operate one or the other, but not both.
That is, the ELT becomes a factor only in the case of a true emergency, in
which case I would first squawk emergency and communicate the situation by
VHF voice (flying the airplane first, of course). Then, activate the ELT
(one button press) if a forced landing appears inevitable, but I'm probably
done talking on the radio at that point.
Is the concern simply the presence of another vertically oriented
conductor in relatively close proximity to the antenna in use, thus influencing
its
performance? Even if both the ELT and the VHF radio are active at the
same time, is 3 ft of separation important?
At any rate, it would be more convenient from an installation perspective
to put them closer together. Any advice?
Thanks,
Paul Kuntz
Message 11
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Subject: | Re: Viking Engine |
classy...
On Fri, Jul 15, 2011 at 5:55 PM, b d <gpabruce@gmail.com> wrote:
> FO
>
> On Fri, Jul 15, 2011 at 2:18 PM, Richard Girard <aslsa.rng@gmail.com>wrote:
>
>> Bruce, The discussion has been interesting to me, certainly more than your
>> rather rude comment.
>>
>> Rick Girard
>>
>> On Fri, Jul 15, 2011 at 11:40 AM, b d <gpabruce@gmail.com> wrote:
>>
>>> WOW, was this spam helpful to anyone? Just curious . . . .
>>>
>>>
>>>
>>>
>>>
>>> On Fri, Jul 15, 2011 at 4:37 AM, <bakerocb@cox.net> wrote:
>>>
>>>>
>>>> 7/15/2011
>>>>
>>>> Congratulations Fellow Amateur Builders,
>>>>
>>>> Several years ago when I first began to read amateur builder postings in
>>>> various venues I was dismayed and concerned about the general lack of
>>>> knowledge regarding the fundamental rules governing our community and
>>>> the
>>>> casual attitude towards such rules. Postings consisting of speculation,
>>>> hearsay, gossip, and rumors would go on at length about any particular
>>>> subject with not one poster citing the fundamental document governing
>>>> the
>>>> subject or even hinting that such a document may even exist.
>>>>
>>>> What a change we have seen. While there was significant thread creep on
>>>> the
>>>> aeroelectric list away from Viking Engine(s) per se in this thread
>>>> several
>>>> posters got directly
>>>> into whatever side path may have been taken and provided clarification
>>>> by
>>>> stating outright, or provided links to, the facts contained in the
>>>> controlling documents.**
>>>>
>>>> Demonstrating this knowlege, and a responsible attitude towards the
>>>> rules,
>>>> is very healthy for our amateur built community as aviation is already
>>>> seen
>>>> by the general public, with significant help from the lame stream media,
>>>> as
>>>> fraught with risky ventures and amateur builders ("nut case builds
>>>> airplane
>>>> in his grarage") as being probably totally irresponsible.
>>>>
>>>> Let's keep up the good work and help stamp out speculation, hearsay,
>>>> gossip,
>>>> and rumors as a means of communication (and confusion for the new guys)
>>>> when
>>>> the facts are usually readily available in this great day of the
>>>> internet.
>>>>
>>>> 'OC' Baker Says: "The best investment we can make is the time and effort
>>>> to
>>>> gather and understand knowledge."
>>>>
>>>> **PS: I am not suggesting that all of the controlling documents (or the
>>>> bureaucrats that enforce them) are all wise and should be followed
>>>> slavishly. I am suggestion that if one decides to deviate from the rules
>>>> that the deviation be done with knowledge and deliberation not out of
>>>> ignorance.
>>>>
>>>> DO NOT ARCHIVE
>>>>
>>>>
>>>>
>>>>
>>>> ====**==============================**=
>>>> -List" target="_blank">http://www.matronics.com/**
>>>> Navigator?AeroElectric-List
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>> Thanks, Homer GBYM
>>
>> It isn't necessary to have relatives in Kansas City in order to be
>> unhappy.
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Message 12
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Subject: | Re: It's nice when the center holds . . . |
But ... the F-16 is a 1980s design, and retro-fitting a gas turbine
generator would be a lot of work to fix what is essentially a
maintenance problem that everyone is already trained to deal with. If
you were designing an all electric airplane today I'm guessing it would
have some kind of turbine based generator to produce a few 10s of kW
that would kick in really quickly.
Peter
For example ...
http://www.lockheedmartin.com/news/press_releases/2005/UNIQUEINTEGRATEDSYSTEMSTARTSF35ENGI.html
Do not archive
On 16/07/2011 15:37, Robert L. Nuckolls, III wrote:
> Given the advances in really tiny gas turbines, it
> seems certainly possible and perhaps practical to
> craft a light weight power generation device with
> considerable output and endurance while using up
> much less volume and weight budget needed for batteries
> of the same capability.
>
> Some ideas take a very long time to evolve into
> useful product . . .
Message 13
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Subject: | Re: It's nice when the center holds . . . |
Reading about the starter-generator-APU brings up a question I've
wondered about many times: why don't piston engines don't have
starter-generators, or starter-alternators, or something like that?
The two devices are so similar it seems like merging the two is
obvious. Surely there must be some basic reason it wouldn't work.
Bob?
Dave Saylor
AirCrafters
140 Aviation Way
Watsonville, CA 95076
831-722-9141 Shop
831-750-0284 Cell
On Sat, Jul 16, 2011 at 2:58 PM, Peter Pengilly <peter@sportingaero.com> wrote:
> <peter@sportingaero.com>
>
> But ... the F-16 is a 1980s design, and retro-fitting a gas turbine
> generator would be a lot of work to fix what is essentially a maintenance
> problem that everyone is already trained to deal with. If you were designing
> an all electric airplane today I'm guessing it would have some kind of
> turbine based generator to produce a few 10s of kW that would kick in really
> quickly.
>
> Peter
>
> For example ...
> http://www.lockheedmartin.com/news/press_releases/2005/UNIQUEINTEGRATEDSYSTEMSTARTSF35ENGI.html
>
> Do not archive
>
> On 16/07/2011 15:37, Robert L. Nuckolls, III wrote:
>>
>> Given the advances in really tiny gas turbines, it
>> seems certainly possible and perhaps practical to
>> craft a light weight power generation device with
>> considerable output and endurance while using up
>> much less volume and weight budget needed for batteries
>> of the same capability.
>>
>> Some ideas take a very long time to evolve into
>> useful product . . .
>
>
Message 14
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Subject: | It's nice when the center holds . . . |
Gentlemen -
The Cliff Notes from a retired F-16-driver buddy:
There are many batteries on the F-16 but they are relatively small. Each of
the axis of the flight control computer has a FLCS battery (3) and then
there are others as well as the A/C battery. But, the EPU, not APU, is an
emergency power unit powered by hydrazine that flows across an iridium
catalyst to product energy. The hydrazine is pressurized with nitrogen I
believe and flows from the tank across the catalyst. It then runs a small
turbine (at a very high rpm) which in turn powers an aux hydraulic pump with
also powers a small aux generator. It is good for a finite period of time
(of which I do not recall) and basically dumps water vapor overboard.
neal
===========
Bob,
I don't know F-16 systems, but have experience of other single seat military
aircraft. I'm guessing the Hydrazine unit is a light weight method of
mitigating the hazard of providing power once the (single) motor has
stopped, without fitting a huge battery. Most combat aircraft are started
with a ground power unit, so the battery doesn't have to be very big. I'm
guessing the electrical demands of an F-16 are quite large (fly-by-wire),
even with load shedding, so a huge battery would be required to get the
airplane to the ground from max altitude - or a reasonably powerful (heavy)
gas turbine APU. So a one shot hydrazine based system is a reasonable (light
weight) solution, although it has a maintenance overhead. Bear in mind the
F-16 was designed as a lightweight fighter, so weight saving was probably
quite high on the priority list.
That's about what I would have guessed.
Some years ago, there was some work described in
the development of tiny, combustion driven turbines
for hi-energy stand-by sources. One author even
hypothesized a lap-top computer running on butane.
Haven't heard/read anything along those lines since.
The GAR series IR guided missiles I used to work on
at Hughes-Tucson had a little bottle of nitrogen
held in liquid state at room temperatures . . . man,
that was a lot of pressure! A frangible diaphragm held
the liquid in check until launch. Then for the 90-second
or so service life of the missile, the liquid expanded
to run a small PM alternator that produced 150 watts
to power electronics. It was then routed to the back of
the IR optics to keep the lens cool at Lots-a-Mach. After
that, it pressurized an open loop hydraulic system that
operated flight controls at the trailing edges of the
guidance fins before being exhausted overboard. That
was in 1960.
Given the advances in really tiny gas turbines, it
seems certainly possible and perhaps practical to
craft a light weight power generation device with
considerable output and endurance while using up
much less volume and weight budget needed for batteries
of the same capability.
Some ideas take a very long time to evolve into
useful product . . .
Bob . . .
Message 15
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Subject: | Re: ELT antenna placement |
It was particularly obnoxious in Phoenix, where the VFR transition over
Sky Harbor has you aimed right at an antenna farm that has 80 percent of
all broadcast stations for the area, distance less than 7 nm. Probably a
few million watts being radiated between the FM and TV stations
transmitters there. As soon as I disconnected the ELT coax from the ELT,
I could fly right up within a mile of those towers with no problem, but
with it connected, as soon as I got within 10 nm constant squelch break
and weak reception both on KX155 and on KX170(McCoy conversion). Had it
happen elsewhere, but not where it caused problems when I had to be in
communication with approach inside Class B airspace. Fixed as soon as I
removed one of Comant 121 antennas from top of fuselage and replaced
with Comant 122 on belly. I've heard of many other ELT installs having
same problem. As you say, I don't think there were a lot of requirements
for RF interference back in 1973 when the TSO was originally written.
On 7/16/2011 8:16 AM, Robert L. Nuckolls, III wrote:
>
> Interesting! I hadn't thought of that scenario. Unlike
> transceivers where the antenna is connected to a receiver
> input circuit 99.9% of the time, the ELT antenna is
> permanently connected to the output circuitry of a
> transmitter's power output stage.
>
> A strong analog TV station impressed on the ELT
> antenna could be conducted into the non-linear,
> transistor junctions where the TV signal could
> produce inter-modulation products that spread over
> a very wide spectrum. Now that we're all-digital
> in the off-air TV world, I suspect probability
> is reduced. I'm aware of no other "trash rich"
> high power signals that would produce this
> effect today.
>
> This is a phenomenon that was never explored
> by DO-160 although I've read some military
> qualification test protocols that do look for
> inter-modulation mixing and re-radiation of
> foreign energies coming down the antenna feedline.
>
>
> Bob . . .
>
>
Message 16
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Subject: | Re: ELT antenna placement |
Thanks for all the feedback. Seems like the prudent approach will be to
accept the ELT installation instructions and mount the ELT at the specified
3+ feet of separation from the VHF antenna. I'd rather do that now than
face the potential for troubleshooting and installation rework later.
Paul Kuntz
On Sat, Jul 16, 2011 at 7:51 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com**>
>
>
> At 07:10 AM 7/16/2011, you wrote:
> dave.saylor.aircrafters@**gmail.com <dave.saylor.aircrafters@gmail.com>>
>
> I agree, I've seen comm radios set of a nearby ELT on several
> occasions. It's not uncommon at all.
>
> I'd keep those antennas away from each other.
>
> It would appear to be the only option. It
> may be very $difficult$ to fix what appears
> to be a design bug internal to the ELT.
>
> The earliest ELT's used a spring-loaded
> mass to close an activation switch in response
> to g-forces of a crash. No doubt modern ELTs
> use the solid-state acceleration sensors
> for this task . . . which produce VERY tiny
> signals requiring a lot of circuit gain.
>
> This type of circuitry offers a high risk
> of vulnerability to RF interference. This
> may be an area where qualification of the
> device to standard DO-160 (good for part
> 23) stresses was insufficient to stand off
> the extra-ordinary vulnerabilities of these
> kinds of circuits. A lot of hardware we
> did for the military and for Part-25 and up
> applications was exposed to really nasty
> RF radiation . . . 200 volts/meter or more
> . . . during qualification. No doubt this
> extra step in qualification would have exposed
> vulnerabilities that are now plaguing customers.
>
> > Paul wrote:
>
> > I'm installing a 121.5/406 MHz ELT in my homebuilt project. =C2 The
>
> > installation instructions tell me to put the ELT whip antenna at least
3
> > feet from my VHF radio antenna. =C2 Is this really necessary? =C2 There
is
> the
>
> > possibility of manually activating the ELT in the air in the event of a
n
> > emergency, while continuing to communicate with the VHF radio, but I'm
> > thinking that the more likely scenarios will be to operate one or the
> other,
> > but not both. =C2 That is, the ELT becomes a factor only in the case of
a
> true
>
> > emergency, in which case I would first squawk emergency and communicate
> the
> > situation by VHF voice (flying the airplane first, of course). =C2 Then
,
>
> > activate the ELT (one button press) if a forced landing appears
> inevitable,
> > but I'm probably done talking on the radio at that point.
> >
> > Is the concern simply the presence of another vertically oriented
> conductor
> > in relatively close proximity to the antenna in use, thus influencing i
ts
> > performance? =C2 Even if both the ELT and the VHF radio are active at t
he
> same
>
> > time, is 3 ft of separation important?
> >
> > At any rate, it would be more convenient from an installation perspecti
ve
> to
> > put them closer together. =C2 Any advice?
>
> Give it a try . . . but with a Plan-B for moving
> one or both of the antennas to achieve demonstrably
> necessary separation. I suspect that not all ELT
> products are victim to the hypothesized vulnerability
> I cited above. There are no grave performance issues
> that would arise from antenna proximity issues so if
> you "get away Scott free" with your desired configuration,
> you're good to go.
>
>
> Bob . . .
>
>
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Message 17
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Subject: | Electrical System Drawing |
Attached is a draft electrical schematic based primarily on Bob Nuckolls'
Z-13 electrical system drawing. Note that I plan on using an internally
regulated Plane Power 30A backup alternator, which is supposed to be out by
Oshkosh. If not, I'll use the B&C SD-20. The reason for the second 7.2 AH
battery is to insure field current to the backup alternator in the event of
main battery failure. I have thought of using a second full sized battery as
the AUX, which I would connect in parallel with the main battery for more
cranking power.
Questions I have are:
Is an Avionics bus & switch unnecessary or is it still a good idea? I like
the idea, and I know the GTX 327 is supposed to be powered off during engine
start. Also the GTN 6xx install doc says it should be on an Avionics bus.
Others have suggested (and even said that Bob Nuckolls doesn't think much of
the idea in his book - although I couldn't find anywhere he discussed it)
that the avionics bus is unnecessary with modern avionics, adds complexity
and additional potential points of failure. Bob doesn't show it on the
drawings I've studied, so I'm wondering.
What are the failure modes of the EBUS Diode? Will it ever fail open? If it
fails and allows reverse current, what is the best way to detect the
failure?
My schematic has a battery bus drawn, but I really don't see a need for it.
Other than a clock and interior lights, is there something that I have
placed on another bus that really should be on a battery bus?
What about the location of the backup alternator?
I show it connected to the essential bus instead of the un-switched side of
the battery contactor, in the event of a dead short in the battery. I'm not
sure if that's a failure mode I need to even consider.
Another thing I've though of is although I haven't done a load analysis yet,
but I'm pretty sure with a 30A backup alternator, I could combine the
Avionics and E-Bus busses (the only things that would be added to the E-BUS
would be Com2, Transponder and audio panel.
Any comments and criticism of the design would be greatly appreciated.
The aircraft I am building is an RV-7A. The mission is day/night IFR.
Thanks Paul
Message 18
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Subject: | Electrical System Drawing |
Attached is a draft electrical schematic based primarily on Bob Nuckolls'
Z-13 electrical system drawing. Note that I plan on using an internally
regulated Plane Power 30A backup alternator, which is supposed to be out by
Oshkosh. If not, I'll use the B&C SD-20. The reason for the second 7.2 AH
battery is to insure field current to the backup alternator in the event of
main battery failure. I have thought of using a second full sized battery as
the AUX, which I would connect in parallel with the main battery for more
cranking power.
Questions I have are:
Is an Avionics bus & switch unnecessary or is it still a good idea? I like
the idea, and I know the GTX 327 is supposed to be powered off during engine
start. Also the GTN 6xx install doc says it should be on an Avionics bus.
Others have suggested (and even said that Bob Nuckolls doesn't think much of
the idea in his book - although I couldn't find anywhere he discussed it)
that the avionics bus is unnecessary with modern avionics, adds complexity
and additional potential points of failure. Bob doesn't show it on the
drawings I've studied, so I'm wondering.
What are the failure modes of the EBUS Diode? Will it ever fail open? If it
fails and allows reverse current, what is the best way to detect the
failure?
My schematic has a battery bus drawn, but I really don't see a need for it.
Other than a clock and interior lights, is there something that I have
placed on another bus that really should be on a battery bus?
What about the location of the backup alternator?
I show it connected to the essential bus instead of the un-switched side of
the battery contactor, in the event of a dead short in the battery. I'm not
sure if that's a failure mode I need to even consider.
Another thing I've though of is although I haven't done a load analysis yet,
but I'm pretty sure with a 30A backup alternator, I could combine the
Avionics and E-Bus busses (the only things that would be added to the E-BUS
would be Com2, Transponder and audio panel.
Any comments and criticism of the design would be greatly appreciated.
The aircraft I am building is an RV-7A. The mission is day/night IFR.
Thanks Paul
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